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Sample records for aircraft fuselage lap

  1. Measurements of fuselage skin strains and displacements near a longitudinal lap joint in a pressurized aircraft

    NASA Technical Reports Server (NTRS)

    Phillips, Edward P.; Britt, Vicki O.

    1991-01-01

    Strains and displacements in a small area near a longitudinal lap joint in the fuselage skin of a B737 aircraft were measured during a pressurization cycle to a differential pressure of 6.2 psi while the aircraft was on the ground. It was found that hoop strains were higher than longitudinal strains at each location; membrane strains in the unreinforced skin were higher than in the joint; membrane strains in the hoop direction, as well as radial displacements, tended to be highest at the mid-bay location between skin reinforcements; significant bending in the hoop direction occurred in the joint and in the skin near the joint, and the bending was unsymmetrically distributed about the stringer at the middle of the joint; and radial displacements were unsymmetrically distributed across the lap joint. The interpretation of the strain gage data for locations on the bonded and riveted lap joint assumed that the joint did not contain disbonded areas.

  2. Evaluation of the fuselage lap joint fatigue and terminating action repair

    NASA Technical Reports Server (NTRS)

    Samavedam, Gopal; Thomson, Douglas; Jeong, David Y.

    1994-01-01

    Terminating action is a remedial repair which entails the replacement of shear head countersunk rivets with universal head rivets which have a larger shank diameter. The procedure was developed to eliminate the risk of widespread fatigue damage (WFD) in the upper rivet row of a fuselage lap joint. A test and evaluation program has been conducted by Foster-Miller, Inc. (FMI) to evaluate the terminating action repair of the upper rivet row of a commercial aircraft fuselage lap splice. Two full scale fatigue tests were conducted on fuselage panels using the growth of fatigue cracks in the lap joint. The second test was performed to evaluate the effectiveness of the terminating action repair. In both tests, cyclic pressurization loading was applied to the panels while crack propagation was recorded at all rivet locations at regular intervals to generate detailed data on conditions of fatigue crack initiation, ligament link-up, and fuselage fracture. This program demonstrated that the terminating action repair substantially increases the fatigue life of a fuselage panel structure and effectively eliminates the occurrence of cracking in the upper rivet row of the lap joint. While high cycle crack growth was recorded in the middle rivet row during the second test, failure was not imminent when the test was terminated after cycling to well beyond the service life. The program also demonstrated that the initiation, propagation, and linkup of WFD in full-scale fuselage structures can be simulated and quantitatively studied in the laboratory. This paper presents an overview of the testing program and provides a detailed discussion of the data analysis and results. Crack distribution and propagation rates and directions as well as frequency of cracking are presented for both tests. The progression of damage to linkup of adjacent cracks and to eventual overall panel failure is discussed. In addition, an assessment of the effectiveness of the terminating action repair and the

  3. Low frequency ultrasonic nondestructive inspection of aluminum/adhesive fuselage lap splices

    SciTech Connect

    Patton, T.

    1994-01-04

    This thesis is a collection of research efforts in ultrasonics, conducted at the Center for Aviation Systems Reliability located at Iowa State University, as part of the Federal Aviation Administration`s ``Aging Aircraft Program.`` The research was directed toward the development of an ultrasonic prototype to inspect the aluminum/adhesive fuselage lap splices found on 1970`s vintage Boeing passenger aircraft. The ultrasonic prototype consists of a normal incidence, low frequency inspection technique, and a scanning adapter that allows focused immersion transducers to be operated in a direct contact manner in any inspection orientation, including upside-down. The inspection technique uses a computer-controlled data acquisition system to produce a C-scan image of a radio frequency (RF) waveform created by a low frequency, broadband, focused beam transducer, driven with a spike voltage pulser. C-scans produced by this technique are color representations of the received signal`s peak-to-peak amplitude (voltage) taken over an (x, y) grid. Low frequency, in this context, refers to a wavelength that is greater than the lap splice`s layer thicknesses. With the low frequency technique, interface echoes of the lap splice are not resolved and gating of the signal is unnecessary; this in itself makes the technique simple to implement and saves considerable time in data acquisition. Along with the advantages in data acquisition, the low frequency technique is relatively insensitive to minor surface curvature and to ultrasonic interference effects caused by adhesive bondline thickness variations in the lap splice.

  4. Experimental and analytical program to determine strains in 737 LAP splice joints subjected to normal fuselage pressurization loads

    SciTech Connect

    Roach, D.P.; Jeong, D.Y.

    1996-02-01

    The Federal Aviation Administration Technical Center (FAATC) has initiated several research projects to assess the structural integrity of the aging commercial aircraft fleet. One area of research involves the understanding of a phenomenon known as ``Widespread Fatigue Damage`` or WFD, which refers to a type of multiple element cracking that degrades the damage tolerance capability of an aircraft structure. Research on WFD has been performed both experimentally and analytically including finite element modeling of fuselage lap splice joints by the Volpe Center. Fuselage pressurization tests have also been conducted at the FAA`s Airworthiness Assurance NDI Validation Center (AANC) to obtain strain gage data from select locations on the FAA/AANC 737 Transport Aircraft Test Bed. One-hundred strain channels were used to monitor five different lap splice bays including the fuselage skin and substructure elements. These test results have been used to evaluate the accuracy of the analytical models and to support general aircraft analysis efforts. This paper documents the strain fields measured during the AANC tests and successfully correlates the results with analytical predictions.

  5. Structural Configuration Systems Analysis for Advanced Aircraft Fuselage Concepts

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek; Welstead, Jason R.; Quinlan, Jesse R.; Guynn, Mark D.

    2016-01-01

    Structural configuration analysis of an advanced aircraft fuselage concept is investigated. This concept is characterized by a double-bubble section fuselage with rear mounted engines. Based on lessons learned from structural systems analysis of unconventional aircraft, high-fidelity finite-element models (FEM) are developed for evaluating structural performance of three double-bubble section configurations. Structural sizing and stress analysis are applied for design improvement and weight reduction. Among the three double-bubble configurations, the double-D cross-section fuselage design was found to have a relatively lower structural weight. The structural FEM weights of these three double-bubble fuselage section concepts are also compared with several cylindrical fuselage models. Since these fuselage concepts are different in size, shape and material, the fuselage structural FEM weights are normalized by the corresponding passenger floor area for a relative comparison. This structural systems analysis indicates that an advanced composite double-D section fuselage may have a relative structural weight ratio advantage over a conventional aluminum fuselage. Ten commercial and conceptual aircraft fuselage structural weight estimates, which are empirically derived from the corresponding maximum takeoff gross weight, are also presented and compared with the FEM- based estimates for possible correlation. A conceptual full vehicle FEM model with a double-D fuselage is also developed for preliminary structural analysis and weight estimation.

  6. Detection of Hidden Cracks on Aircraft LAP Joints with GMR Based Eddy Current Technology

    SciTech Connect

    Na, J. K.; Franklin, M. A.; Linn, J. R.

    2006-03-06

    Cracks occurring on commercial aircraft fuselage lap joints made of aluminum alloys often caused by scribe lines made during the removal of process of moisture sealing materials between two layers. These cracks on thinner bottom skin layers can be obscured by thicker top plates with paint. A portable GMR (Giant Magnetoresistive) sensor based eddy current system has been developed and tested on several simulated aircraft lap joints samples with EDM notches. Various thicknesses of layers are used to simulate the test as used on different combinations of lap joints. Length and depth of cracks are important factors for the safety of aircraft. Test results are used to come up with a portable nondestructive inspection system which is easy and fast with a high reliability of detecting cracks longer than a half inch in length and 0.010 inches in depth.

  7. Structural-acoustic coupling in aircraft fuselage structures

    NASA Technical Reports Server (NTRS)

    Mathur, Gopal P.; Simpson, Myles A.

    1992-01-01

    Results of analytical and experimental investigations of structural-acoustic coupling phenomenon in an aircraft fuselage are described. The structural and acoustic cavity modes of DC-9 fuselage were determined using a finite element approach to vibration analysis. Predicted structural and acoustic dispersion curves were used to determine possible occurrences of structural-acoustic coupling for the fuselage. An aft section of DC-9 aircraft fuselage, housed in an anechoic chamber, was used for experimental investigations. The test fuselage was excited by a shaker and vibration response and interior sound field were measured using accelerometer and microphone arrays. The wavenumber-frequency structural and cavity response maps were generated from the measured data. Analysis and interpretation of the spatial plots and wavenumber maps provided the required information on modal characteristics, fuselage response and structural-acoustic coupling.

  8. The Characteristics of Fatigue Damage in the Fuselage Riveted Lap Splice Joint

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Willard, Scott A.

    1997-01-01

    An extensive data base has been developed to form the physical basis for new analytical methodology to predict the onset of widespread fatigue damage in the fuselage lap splice joint. The results of detailed destructive examinations have been cataloged to describe the physical nature of MSD in the lap splice joint. ne catalog includes a detailed description, e.g., crack initiation, growth rates, size, location, and fracture morphology, of fatigue damage in the fuselage lap splice joint structure. Detailed examinations were conducted on a lap splice joint panel removed from a full scale fuselage test article after completing a 60,000 cycle pressure test. The panel contained a four bay region that exhibited visible outer skin cracks and regions of crack link-up along the upper rivet row. Destructive examinations revealed undetected fatigue damage in the outer skin, inner skin, and tear strap regions. Outer skin fatigue cracks were found to initiate by fretting damage along the faying surface. The cracks grew along the faying surface to a length equivalent to two to three skin thicknesses before penetrating the outboard surface of the outer skin. Analysis of fracture surface marker bands produced during full scale testing revealed that all upper rivet row fatigue cracks contained in a dim bay region grow at similar rates; this important result suggests that fracture mechanics based methods can be used to predict the growth of outer skin fatigue cracks in lap splice structure. Results are presented showing the affects of MSD and out-of-plane pressure loads on outer skin crack link-up.

  9. Design-Oriented Analysis of Aircraft Fuselage Structures

    NASA Technical Reports Server (NTRS)

    Giles, Gary L.

    1998-01-01

    A design-oriented analysis capability for aircraft fuselage structures that utilizes equivalent plate methodology is described. This new capability is implemented as an addition to the existing wing analysis procedure in the Equivalent Laminated Plate Solution (ELAPS) computer code. The wing and fuselage analyses are combined to model entire airframes. The paper focuses on the fuselage model definition, the associated analytical formulation and the approach used to couple the wing and fuselage analyses. The modeling approach used to minimize the amount of preparation of input data by the user and to facilitate the making of design changes is described. The fuselage analysis is based on ring and shell equations but the procedure is formulated to be analogous to that used for plates in order to take advantage of the existing code in ELAPS. Connector springs are used to couple the wing and fuselage models. Typical fuselage analysis results are presented for two analytical models. Results for a ring-stiffened cylinder model are compared with results from conventional finite-element analyses to assess the accuracy of this new analysis capability. The connection of plate and ring segments is demonstrated using a second model that is representative of the wing structure for a channel-wing aircraft configuration.

  10. Design considerations for composite fuselage structure of commercial transport aircraft

    NASA Technical Reports Server (NTRS)

    Davis, G. W.; Sakata, I. F.

    1981-01-01

    The structural, manufacturing, and service and environmental considerations that could impact the design of composite fuselage structure for commercial transport aircraft application were explored. The severity of these considerations was assessed and the principal design drivers delineated. Technical issues and potential problem areas which must be resolved before sufficient confidence is established to commit to composite materials were defined. The key issues considered are: definition of composite fuselage design specifications, damage tolerance, and crashworthiness.

  11. Determination of the Corrosive Conditions Present within Aircraft Lap-Splice Joints

    NASA Technical Reports Server (NTRS)

    Lewis, Karen S.; Kelly, Robert G.; Piascik, Robert S.

    1999-01-01

    The complexity of airframe structure lends itself to damage resulting from crevice corrosion. Fuselage lap-splice joints are a particularly important structural detail in this regard because of the difficulty associated with detection and measurement of corrosion in these occluded regions. The objective of this work is to develop a laboratory corrosion test protocol to identify the chemistry to which lap joints are exposed and to develop a model of the corrosion within the joints. A protocol for collecting and identifying the chemistry of airframe crevice corrosion has been developed. Capillary electrophoresis (CE) is used to identify the ionic species contained in corrosion product samples removed from fuselage lap splice joints. CE analysis has been performed on over sixty corrosion product samples removed from both civilian and military aircraft. Over twenty different ions have been detected. Measurements of pH of wetted corroded surfaces indicated an alkaline occluded solution. After determining the species present and their relative concentrations, the resultant solution was reproduced in bulk and electrochemical tests were performed to determine the corrosion rate. Electrochemical analyses of the behavior of AA2024-T3 in these solutions gave corrosion rates of up to 250 microns per year (10 mpy). Additional tests have determined the relative importance of each of the detected ions in model solutions used for future predictive tests. The statistically significant ions have been used to create a second generation solution. Laboratory studies have also included exposure tests involving artificial lap joints exposed to various simulated bulk and crevice environments. The extent and morphology of the attack in artificial lap joints has been compared to studies of corroded samples from actual aircraft. Other effects, such as temperature and potential, as well as the impact of the environment on fatigue crack growth have also been studied.

  12. Composite Structure Modeling and Analysis of Advanced Aircraft Fuselage Concepts

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek; Sorokach, Michael R.

    2015-01-01

    NASA Environmentally Responsible Aviation (ERA) project and the Boeing Company are collabrating to advance the unitized damage arresting composite airframe technology with application to the Hybrid-Wing-Body (HWB) aircraft. The testing of a HWB fuselage section with Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) construction is presently being conducted at NASA Langley. Based on lessons learned from previous HWB structural design studies, improved finite-element models (FEM) of the HWB multi-bay and bulkhead assembly are developed to evaluate the performance of the PRSEUS construction. In order to assess the comparative weight reduction benefits of the PRSEUS technology, conventional cylindrical skin-stringer-frame models of a cylindrical and a double-bubble section fuselage concepts are developed. Stress analysis with design cabin-pressure load and scenario based case studies are conducted for design improvement in each case. Alternate analysis with stitched composite hat-stringers and C-frames are also presented, in addition to the foam-core sandwich frame and pultruded rod-stringer construction. The FEM structural stress, strain and weights are computed and compared for relative weight/strength benefit assessment. The structural analysis and specific weight comparison of these stitched composite advanced aircraft fuselage concepts demonstrated that the pressurized HWB fuselage section assembly can be structurally as efficient as the conventional cylindrical fuselage section with composite stringer-frame and PRSEUS construction, and significantly better than the conventional aluminum construction and the double-bubble section concept.

  13. Analytical Fuselage and Wing Weight Estimation of Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Chambers, Mark C.; Ardema, Mark D.; Patron, Anthony P.; Hahn, Andrew S.; Miura, Hirokazu; Moore, Mark D.

    1996-01-01

    A method of estimating the load-bearing fuselage weight and wing weight of transport aircraft based on fundamental structural principles has been developed. This method of weight estimation represents a compromise between the rapid assessment of component weight using empirical methods based on actual weights of existing aircraft, and detailed, but time-consuming, analysis using the finite element method. The method was applied to eight existing subsonic transports for validation and correlation. Integration of the resulting computer program, PDCYL, has been made into the weights-calculating module of the AirCraft SYNThesis (ACSYNT) computer program. ACSYNT has traditionally used only empirical weight estimation methods; PDCYL adds to ACSYNT a rapid, accurate means of assessing the fuselage and wing weights of unconventional aircraft. PDCYL also allows flexibility in the choice of structural concept, as well as a direct means of determining the impact of advanced materials on structural weight. Using statistical analysis techniques, relations between the load-bearing fuselage and wing weights calculated by PDCYL and corresponding actual weights were determined.

  14. Finite Element Model Development For Aircraft Fuselage Structures

    NASA Technical Reports Server (NTRS)

    Buehrle, Ralph D.; Fleming, Gary A.; Pappa, Richard S.; Grosveld, Ferdinand W.

    2000-01-01

    The ability to extend the valid frequency range for finite element based structural dynamic predictions using detailed models of the structural components and attachment interfaces is examined for several stiffened aircraft fuselage structures. This extended dynamic prediction capability is needed for the integration of mid-frequency noise control technology. Beam, plate and solid element models of the stiffener components are evaluated. Attachment models between the stiffener and panel skin range from a line along the rivets of the physical structure to a constraint over the entire contact surface. The finite element models are validated using experimental modal analysis results.

  15. Aeroelastic Analysis of Aircraft: Wing and Wing/Fuselage Configurations

    NASA Technical Reports Server (NTRS)

    Chen, H. H.; Chang, K. C.; Tzong, T.; Cebeci, T.

    1997-01-01

    A previously developed interface method for coupling aerodynamics and structures is used to evaluate the aeroelastic effects for an advanced transport wing at cruise and under-cruise conditions. The calculated results are compared with wind tunnel test data. The capability of the interface method is also investigated for an MD-90 wing/fuselage configuration. In addition, an aircraft trim analysis is described and applied to wing configurations. The accuracy of turbulence models based on the algebraic eddy viscosity formulation of Cebeci and Smith is studied for airfoil flows at low Mach numbers by using methods based on the solutions of the boundary-layer and Navier-Stokes equations.

  16. Initiation and growth of multiple-site damage in the riveted lap joint of a curved stiffened fuselage panel: An experimental and analytical study

    NASA Astrophysics Data System (ADS)

    Ahmed, Abubaker Ali

    As part of the structural integrity research of the National Aging Aircraft Research Program, a comprehensive study on multiple-site damage (MSD) initiation and growth in a pristine lap-joint fuselage panel has been conducted. The curved stiffened fuselage panel was tested at the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center. A strain survey test was conducted to verify proper load application. The panel was then subjected to a fatigue test with constant-amplitude cyclic loading. The applied loading spectrum included underload marker cycles so that crack growth history could be reconstructed from post-test fractographic examinations. Crack formation and growth were monitored via nondestructive and high-magnification visual inspections. Strain gage measurements recorded during the strain survey tests indicated that the inner surface of the skin along the upper rivet row of the lap joint experienced high tensile stresses due to local bending. During the fatigue loading, cracks were detected by eddy-current inspections at multiple rivet holes along the upper rivet row. Through-thickness cracks were detected visually after about 80% of the fatigue life. Once MSD cracks from two adjacent rivet holes linked up, there was a quick deterioration in the structural integrity of the lap joint. The linkup resulted in a 2.87" (72.9-mm) lead fatigue crack that rapidly propagated across 12 rivet holes and crossed over into the next skin bay, at which stage the fatigue test was terminated. A post-fatigue residual strength test was then conducted by loading the panel quasi-statically up to final failure. The panel failed catastrophically when the crack extended instantaneously across three additional bays. Post-test fractographic examinations of the fracture surfaces in the lap joint of the fuselage panel were conducted to characterize subsurface crack initiation and

  17. Non-waisted fuselage design for supersonic aircraft

    NASA Technical Reports Server (NTRS)

    Hager, James O. (Inventor); Agrawal, Shreekant (Inventor); Antani, Dhamanshu L. (Inventor)

    1999-01-01

    A method for designing a non-waisted fuselage for supersonic wing/fuselage configurations that increases the fuselage volume and improves the supersonic aerodynamic performance compared to a conventional waisted-fuselage configuration. The method entails removing the waisted region of an existing waisted-fuselage configuration by linearly reconstructing cross-sections between the endpoints representing the waisted cross-sectional area portion to create a modified fuselage configuration without waisting. This configuration will have increased fuselage volume and improved supersonic aerodynamic performance. The fuselage camber can then be optimized using non-linear aerodynamic methods to further increase the supersonic aerodynamic performance.

  18. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles: Aircraft design evaluation

    NASA Technical Reports Server (NTRS)

    Nobe, T.

    1975-01-01

    The effects of fuselage cross sections and structural members on the performance of hypersonic cruise aircraft are evaluated. Representative fuselage/tank area structure was analyzed for strength, stability, fatigue and fracture mechanics. Various thermodynamic and structural tradeoffs were conducted to refine the conceptual designs with the primary objective of minimizing weight and maximizing aircraft range.

  19. Finite Element Model Development and Validation for Aircraft Fuselage Structures

    NASA Technical Reports Server (NTRS)

    Buehrle, Ralph D.; Fleming, Gary A.; Pappa, Richard S.; Grosveld, Ferdinand W.

    2000-01-01

    The ability to extend the valid frequency range for finite element based structural dynamic predictions using detailed models of the structural components and attachment interfaces is examined for several stiffened aircraft fuselage structures. This extended dynamic prediction capability is needed for the integration of mid-frequency noise control technology. Beam, plate and solid element models of the stiffener components are evaluated. Attachment models between the stiffener and panel skin range from a line along the rivets of the physical structure to a constraint over the entire contact surface. The finite element models are validated using experimental modal analysis results. The increased frequency range results in a corresponding increase in the number of modes, modal density and spatial resolution requirements. In this study, conventional modal tests using accelerometers are complemented with Scanning Laser Doppler Velocimetry and Electro-Optic Holography measurements to further resolve the spatial response characteristics. Whenever possible, component and subassembly modal tests are used to validate the finite element models at lower levels of assembly. Normal mode predictions for different finite element representations of components and assemblies are compared with experimental results to assess the most accurate techniques for modeling aircraft fuselage type structures.

  20. Fatigue damage assessment of high-usage in-service aircraft fuselage structure

    NASA Astrophysics Data System (ADS)

    Mosinyi, Bao Rasebolai

    As the commercial and military aircraft fleets continue to age, there is a growing concern that multiple-site damage (MSD) can compromise structural integrity. Multiple site damage is the simultaneous occurrence of many small cracks at independent structural locations, and is the natural result of fatigue, corrosion, fretting and other possible damage mechanisms. These MSD cracks may linkup and form a fatigue lead crack of critical length. The presence of MSD also reduces the structure's ability to withstand longer cracks. The objective of the current study is to assess, both experimentally and analytically, MSD formation and growth in the lap joint of curved panels removed from a retired aircraft. A Boeing 727-232 airplane owned and operated by Delta Air Lines, and retired at its design service goal, was selected for the study. Two panels removed from the left-hand side of the fuselage crown, near stringer 4L, were subjected to extended fatigue testing using the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration (FAA) William J. Hughes Technical Center. The state of MSD was continuously assessed using several nondestructive inspection (NDI) methods. Damage to the load attachment points of the first panel resulted in termination of the fatigue test at 43,500 fatigue cycles, before cracks had developed in the lap joint. The fatigue test for the second panel was initially conducted under simulated in-service loading conditions for 120,000 cycles, and no cracks were detected in the skin of the panel test section. Artificial damage was then introduced into the panel at selected rivets in the critical (lower) rivet row, and the fatigue loads were increased. Visually detectable crack growth from the artificial notches was first seen after 133,000 cycles. The resulting lead crack grew along the lower rivet row, eventually forming an 11.8" long unstable crack after 141,771 cycles, at which point the

  1. Development of pressure containment and damage tolerance technology for composite fuselage structures in large transport aircraft

    NASA Technical Reports Server (NTRS)

    Smith, P. J.; Thomson, L. W.; Wilson, R. D.

    1986-01-01

    NASA sponsored composites research and development programs were set in place to develop the critical engineering technologies in large transport aircraft structures. This NASA-Boeing program focused on the critical issues of damage tolerance and pressure containment generic to the fuselage structure of large pressurized aircraft. Skin-stringer and honeycomb sandwich composite fuselage shell designs were evaluated to resolve these issues. Analyses were developed to model the structural response of the fuselage shell designs, and a development test program evaluated the selected design configurations to appropriate load conditions.

  2. Experimental and numerical analyses of laminar boundary-layer flow stability over an aircraft fuselage forebody

    NASA Technical Reports Server (NTRS)

    Vijgen, Paul M. H. W.; Holmes, Bruce J.

    1987-01-01

    Fuelled by a need to reduce viscous drag of airframes, significant advances have been made in the last decade to design lifting surface geometries with considerable amounts of laminar flow. In contrast to the present understanding of practical limits for natural laminar flow over lifting surfaces, limited experimental results are available examining applicability of natural laminar flow over axisymmetric and nonaxisymmetric fuselage shapes at relevantly high length Reynolds numbers. The drag benefits attainable by realizing laminar flow over nonlifting aircraft components such as fuselages and nacelles are shown. A flight experiment to investigate transition location and transition mode over the forward fuselage of a light twin engine propeller driven airplane is examined.

  3. A record of all marker bands found in the upper rivet rows of 2 adjacent bays from a fuselage lap splice joint

    NASA Technical Reports Server (NTRS)

    Willard, Scott A.

    1995-01-01

    A full scale fuselage test article was subjected to 60,000 load cycles (pressurizations) to study the effect of widespread fatigue damage in fuselage structures. Every 10,000 cycles coded marker block loading sequences were used to mark the fracture surfaces of the fatigue cracks propagating within the panel. The loading sequences consisted of series of underloads combined with a series of full pressurizations. The combination of loads and underloads marked the fracture surfaces with marker bands that could later be used to reconstruct the fatigue crack growth history of selected regions within the test article. Thirty rivet holes comprising the upper rivet rows from two adjacent bays (bays #3 and #4) from a fuselage lap splice joint were examined for the purpose of this study. Optical and scanning electron microscopy (SEM) were used to locate the marker bands.

  4. A Study of the Utilization of Advanced Composites in Fuselage Structures of Commercial Aircraft

    NASA Technical Reports Server (NTRS)

    Watts, D. J.; Sumida, P. T.; Bunin, B. L.; Janicki, G. S.; Walker, J. V.; Fox, B. R.

    1985-01-01

    A study was conducted to define the technology and data needed to support the introduction of advanced composites in the future production of fuselage structure in large transport aircraft. Fuselage structures of six candidate airplanes were evaluated for the baseline component. The MD-100 was selected on the basis of its representation of 1990s fuselage structure, an available data base, its impact on the schedule and cost of the development program, and its availability and suitability for flight service evaluation. Acceptance criteria were defined, technology issues were identified, and a composite fuselage technology development plan, including full-scale tests, was identified. The plan was based on composite materials to be available in the mid to late 1980s. Program resources required to develop composite fuselage technology are estimated at a rough order of magnitude to be 877 man-years exclusive of the bird strike and impact dynamic test components. A conceptual composite fuselage was designed, retaining the basic MD-100 structural arrangement for doors, windows, wing, wheel wells, cockpit enclosure, major bulkheads, etc., resulting in a 32 percent weight savings.

  5. Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss

    NASA Technical Reports Server (NTRS)

    Carney, Kelly; Pereira, Michael; Kohlman, Lee; Goldberg, Robert; Envia, Edmane; Lawrence, Charles; Roberts, Gary; Emmerling, William

    2013-01-01

    The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the

  6. Experimental modal analysis of the fuselage panels of an Aero Commander aircraft

    NASA Technical Reports Server (NTRS)

    Geisler, D.

    1981-01-01

    The reduction of interior noise in light aircraft was investigated with emphasis the thin fuselage sidewall. The approach used is theoretical and involves modeling of the sidewall panels and stiffeners. Experimental data obtained from tests investigating the effects of mass and stiffness treatments to the sidewalls are presented. The dynamic characteristics of treated panels are contrasted with the untreated sidewall panels using experimental modal analysis techniques. The results include the natural frequencies, modal dampling, and mode shapes of selected panels. Frequency response functions, data relating to the global fuselage response, and acoustic response are also presented.

  7. Interior and exterior fuselage noise measured on NASA's C-8a augmentor wing jet-STOL research aircraft

    NASA Technical Reports Server (NTRS)

    Shovlin, M. D.

    1977-01-01

    Interior and exterior fuselage noise levels were measured on NASA's C-8A Augmentor Wing Jet-STOL Research Aircraft in order to provide design information for the Quiet Short-Haul Research Aircraft (QSRA), which will use a modified C-8A fuselage. The noise field was mapped by 11 microphones located internally and externally in three areas: mid-fuselage, aft fuselage, and on the flight deck. Noise levels were recorded at four power settings varying from takeoff to flight idle and were plotted in one-third octave band spectra. The overall sound pressure levels of the external noise field were compared to previous tests and found to correlate well with engine primary thrust levels. Fuselage values were 145 + or - 3 dB over the aircraft's normal STOL operating range.

  8. Application study of filamentary composites in a commercial jet aircraft fuselage

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.; June, R. R.

    1972-01-01

    A study of applications of filamentary composite materials to aircraft fuselage structure was performed. General design criteria were established and material studies conducted using the 727-200 forebody as the primary structural component. Three design approaches to the use of composites were investigated: uniaxial reinforcement of metal structure, uniaxial and biaxial reinforcement of metal structure, and an all-composite design. Materials application studies for all three concepts were conducted on fuselage shell panels, keel beam, floor beams, floor panels, body frames, fail-safe straps, and window frames. Cost benefit studies were conducted and developmental program costs estimated. On the basis of weight savings, cost effectiveness, developmental program costs, and potential for early application on commercial aircraft, the unaxial design is recommended for a 5-year flight service evaluation program.

  9. Development of a biaxial test facility for structural evaluation of aircraft fuselage panels

    SciTech Connect

    Roach, D.; Walkington, P.; Rice, T.

    1998-03-01

    The number of commercial airframes exceeding twenty years of service continues to grow. An unavoidable by-product of aircraft use is that crack and corrosion flaws develop throughout the aircraft`s skin and substructure elements. Economic barriers to the purchase of new aircraft have created an aging aircraft fleet and placed even greater demands on efficient and safe repair methods. Composite doublers, or repair patches, provide an innovative repair technique which can enhance the way aircraft are maintained. Instead of riveting multiple steel or aluminum plates to facilitate an aircraft repair, it is now possible to bond a single Boron-Epoxy composite doubler to the damaged structure. The composite doubler repair process produces both engineering and economic benefits. The FAA`s Airworthiness Assurance Center at Sandia National Labs completed a project to introduce composite doubler repair technology to the commercial aircraft industry. This paper focuses on a specialized structural test facility which was developed to evaluate the performance of composite doublers on actual aircraft structure. The facility can subject an aircraft fuselage section to a combined load environment of pressure (hoop stress) and axial, or longitudinal, stress. The tests simulate maximum cabin pressure loads and use a computerized feedback system to maintain the proper ratio between hoop and axial loads. Through the use of this full-scale test facility it was possible to: (1) assess general composite doubler response in representative flight load scenarios, and (2) verify the design and analysis approaches as applied to an L-1011 door corner repair.

  10. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles, summary. [aircraft design of aircraft fuel systems

    NASA Technical Reports Server (NTRS)

    Pirrello, C. J.; Baker, A. H.; Stone, J. E.

    1976-01-01

    A detailed analytical study was made to investigate the effects of fuselage cross section (circular and elliptical) and the structural arrangement (integral and nonintegral tanks) on aircraft performance. The vehicle was a 200 passenger, liquid hydrogen fueled Mach 6 transport designed to meet a range goal of 9.26 Mn (5000 NM). A variety of trade studies were conducted in the area of configuration arrangement, structural design, and active cooling design in order to maximize the performance of each of three point design aircraft: (1) circular wing-body with nonintegral tanks, (2) circular wing-body with integral tanks and (3) elliptical blended wing-body with integral tanks. Aircraft range and weight were used as the basis for comparison. The resulting design and performance characteristics show that the blended body integral tank aircraft weights the least and has the greatest range capability, however, producibility and maintainability factors favor nonintegral tank concepts.

  11. Classification of fatigue cracking data in a simulated aircraft fuselage using a self-organizing map

    SciTech Connect

    Marsden, M.L.; Hill, E.V.K.

    1994-12-31

    Many aircraft are being flown beyond their design lifespans and have therefore fallen victim to fatigue cracking. In some cases, such as the 1988 Aloha Airlines 737-200 incident, catastrophic fatigue growth has caused the loss of life. Acoustic emission (AE) nondestructive testing has been used to detect and classical the growth of fatigue cracks in complex structures, such as aircraft fuselages and wings since as early as 1979. In order to simulate an aircraft fuselage undergoing pressurization cycle fatigue, a test was developed in which a thin-walled aluminum pressure vessel was instrumented with AE sensors and cyclically fatigued to promote crack growth at a stress concentration built into the vessel. The AE data acquisition system. extracted the six AE parameters - amplitude, counts, duration, energy, risetime, and count-to-peak from each of the sensor signals. One-third of these parameter data sets were used to tram a Kohonen self-organizing map (SOM) neural network. The remaining data sets were used to test the SOM. The SOM output is a two-dimensional map with similar input data sets located at similar coordinates on the map. Because the continuous AE parameter data are grouped into discrete bands or intervals, e.g., all the events having amplitudes between 51.00 dB and 51.99 dB are classified as 51 dB events, the initial SOM output showed no distinct clustering. However, when the output was transformed into three-dimensions, with the third dimension being the frequency of occurrence of each two-dimensional coordinate, several distinct peaks were evident. These peaks correspond to the three AE source in the vessel: metal rubbing, rivet fretting, and fatigue cracking. Thus, the three-dimensional SOM was able to unambiguously classify fatigue crack growth events in a simulated aircraft fuselage structure.

  12. Sound Pressures and Correlations of Noise on the Fuselage of a Jet Aircraft in Flight

    NASA Technical Reports Server (NTRS)

    Shattuck, Russell D.

    1961-01-01

    Tests were conducted at altitudes of 10,000, 20,000, and 30,000 feet at speeds of Mach 0.4, 0.6, and O.8. It was found that the sound pressure levels on the aft fuselage of a jet aircraft in flight can be estimated using an equation involving the true airspeed and the free air density. The cross-correlation coefficient over a spacing of 2.5 feet was generalized with Strouhal number. The spectrum of the noise in flight is comparatively flat up to 10,000 cycles per second.

  13. Aircraft Engine Noise Scattering by Fuselage and Wings: A Computational Approach

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Stanescu, D.; Hussaini, M. Y.

    2003-01-01

    The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far field. The effects of non-uniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. The approach is based on the discretization of the inviscid flow equations through a collocation form of the discontinuous Galerkin spectral element method. An isoparametric representation of the underlying geometry is used in order to take full advantage of the spectral accuracy of the method. Large-scale computations are made possible by a parallel implementation based on message passing. Results obtained for radiation from an axisymmetric nacelle alone are compared with those obtained when the same nacelle is installed in a generic configuration, with and without a wing. 0 2002 Elsevier Science Ltd. All rights reserved.

  14. Aircraft Engine Noise Scattering by Fuselage and Wings: A Computational Approach

    NASA Technical Reports Server (NTRS)

    Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2003-01-01

    The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far-field. The effects of nonuniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. The approach is based on the discretization of the inviscid flow equations through a collocation form of the Discontinuous Galerkin spectral element method. An isoparametric representation of the underlying geometry is used in order to take full advantage of the spectral accuracy of the method. Large-scale computations are made possible by a parallel implementation based on message passing. Results obtained for radiation from an axisymmetric nacelle alone are compared with those obtained when the same nacelle is installed in a generic configuration, with and without a wing.

  15. Aircraft Engine Noise Scattering By Fuselage and Wings: A Computational Approach

    NASA Technical Reports Server (NTRS)

    Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2003-01-01

    The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far-field. The effects of nonuniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. The approach is based on the discretization of the inviscid flow equations through a collocation form of the Discontinuous Galerkin spectral element method. An isoparametric representation of the underlying geometry is used in order to take full advantage of the spectral accuracy of the method. Large-scale computations are made possible by a parallel implementation based on message passing. Results obtained for radiation from an axisymmetric nacelle alone are compared with those obtained when the same nacelle is installed in a generic configuration, with and without a wing.

  16. Crashworthiness of light aircraft fuselage structures: A numerical and experimental investigation

    NASA Technical Reports Server (NTRS)

    Nanyaro, A. P.; Tennyson, R. C.; Hansen, J. S.

    1984-01-01

    The dynamic behavior of aircraft fuselage structures subject to various impact conditions was investigated. An analytical model was developed based on a self-consistent finite element (CFE) formulation utilizing shell, curved beam, and stringer type elements. Equations of motion were formulated and linearized (i.e., for small displacements), although material nonlinearity was retained to treat local plastic deformation. The equations were solved using the implicit Newmark-Beta method with a frontal solver routine. Stiffened aluminum fuselage models were also tested in free flight using the UTIAS pendulum crash test facility. Data were obtained on dynamic strains, g-loads, and transient deformations (using high speed photography in the latter case) during the impact process. Correlations between tests and predicted results are presented, together with computer graphics, based on the CFE model. These results include level and oblique angle impacts as well as the free-flight crash test. Comparisons with a hybrid, lumped mass finite element computer model demonstrate that the CFE formulation provides the test overall agreement with impact test data for comparable computing costs.

  17. Full-scale testing and progressive damage modeling of sandwich composite aircraft fuselage structure

    NASA Astrophysics Data System (ADS)

    Leone, Frank A., Jr.

    A comprehensive experimental and computational investigation was conducted to characterize the fracture behavior and structural response of large sandwich composite aircraft fuselage panels containing artificial damage in the form of holes and notches. Full-scale tests were conducted where panels were subjected to quasi-static combined pressure, hoop, and axial loading up to failure. The panels were constructed using plain-weave carbon/epoxy prepreg face sheets and a Nomex honeycomb core. Panel deformation and notch tip damage development were monitored during the tests using several techniques, including optical observations, strain gages, digital image correlation (DIC), acoustic emission (AE), and frequency response (FR). Additional pretest and posttest inspections were performed via thermography, computer-aided tap tests, ultrasound, x-radiography, and scanning electron microscopy. The framework to simulate damage progression and to predict residual strength through use of the finite element (FE) method was developed. The DIC provided local and full-field strain fields corresponding to changes in the state-of-damage and identified the strain components driving damage progression. AE was monitored during loading of all panels and data analysis methodologies were developed to enable real-time determination of damage initiation, progression, and severity in large composite structures. The FR technique has been developed, evaluating its potential as a real-time nondestructive inspection technique applicable to large composite structures. Due to the large disparity in scale between the fuselage panels and the artificial damage, a global/local analysis was performed. The global FE models fully represented the specific geometries, composite lay-ups, and loading mechanisms of the full-scale tests. A progressive damage model was implemented in the local FE models, allowing the gradual failure of elements in the vicinity of the artificial damage. A set of modifications

  18. Nonlinear Acoustic Response of an Aircraft Fuselage Sidewall Structure by a Reduced-Order Analysis

    NASA Technical Reports Server (NTRS)

    Przekop, Adam; Rizzi, Stephen A.; Groen, David S.

    2006-01-01

    A reduced-order nonlinear analysis of a structurally complex aircraft fuselage sidewall panel is undertaken to explore issues associated with application of such analyses to practical structures. Of primary interest is the trade-off between computational efficiency and accuracy. An approach to modal basis selection is offered based upon the modal participation in the linear regime. The nonlinear static response to a uniform pressure loading and nonlinear random response to a uniformly distributed acoustic loading are computed. Comparisons of the static response with a nonlinear static solution in physical degrees-of-freedom demonstrate the efficacy of the approach taken for modal basis selection. Changes in the modal participation as a function of static and random loading levels suggest a means for improvement in the basis selection.

  19. A theoretical investigation of noise reduction through the cylindrical fuselage of a twin-engine, propeller-driven aircraft

    NASA Technical Reports Server (NTRS)

    Bhat, R. B.; Mixson, J. S.

    1978-01-01

    Interior noise in the fuselage of a twin-engine, propeller-driven aircraft with two propellers rotating in opposite directions is studied analytically. The fuselage was modeled as a stiffened cylindrical shell with simply supported ends, and the effects of stringers and frames were averaged over the shell surface. An approximate mathematical model of the propeller noise excitation was formulated which includes some of the propeller noise characteristics such as sweeping pressure waves around the sidewalls due to propeller rotation and the localized nature of the excitation with the highest levels near the propeller plane. Results are presented in the form of noise reduction, which is the difference between the levels of external and interior noise. The influence of propeller noise characteristics on the noise reduction was studied. The results indicate that the sweep velocity of the excitation around the fuselage sidewalls is critical to noise reduction.

  20. Laboratory tests on an aircraft fuselage to determine the insertion loss of various acoustic add-on treatments

    NASA Technical Reports Server (NTRS)

    Heitman, K. E.; Mixson, J. S.

    1984-01-01

    This paper describes a laboratory study of add-on acoustic treatments for a propeller-driven light aircraft fuselage. The treatments included: no treatment (i.e., baseline fuselage); a production-type double-wall interior; and various amounts of high density fiberglass added to the baseline fuselage. The sound source was a pneumatic-driver with attached exponential horn, supplied with a broadband signal. Data were acquired at the approximate head positions of the six passenger seats. The results were analyzed on space-averaged narrowband, one-third octave band and overall insertion loss basis. In addition, insertion loss results for the different configurations at specific frequencies representing propeller tone spectra are presented. The propeller tone data includes not only the space-averaged insertion loss, but also the variation of insertion loss at these particular frequencies across the six microphone positions.

  1. Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure . Part II; Severe Damage

    NASA Technical Reports Server (NTRS)

    Przekop, Adam; Jegley, Dawn C.; Lovejoy, Andrew E.; Rouse, Marshall; Wu, Hsi-Yung T.

    2016-01-01

    The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a finite element analysis and the testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part II of the paper considers the final test to failure of the test article in the presence of an intentionally inflicted severe discrete source damage under the wing up-bending loading condition. Finite element analysis results are compared with measurements acquired during the test and demonstrate that the hybrid wing body test article was able to redistribute and support the required design loads in a severely damaged condition.

  2. Nonlinear Finite Element Analysis of a Composite Non-Cylindrical Pressurized Aircraft Fuselage Structure

    NASA Technical Reports Server (NTRS)

    Przekop, Adam; Wu, Hsi-Yung T.; Shaw, Peter

    2014-01-01

    The Environmentally Responsible Aviation Project aims to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration are not sufficient to achieve the desired metrics. One of the airframe concepts that might dramatically improve aircraft performance is a composite-based hybrid wing body configuration. Such a concept, however, presents inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a nonlinear finite element analysis of a large-scale test article being developed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. There are specific reasons why geometrically nonlinear analysis may be warranted for the hybrid wing body flat panel structure. In general, for sufficiently high internal pressure and/or mechanical loading, energy related to the in-plane strain may become significant relative to the bending strain energy, particularly in thin-walled areas such as the minimum gage skin extensively used in the structure under analysis. To account for this effect, a geometrically nonlinear strain-displacement relationship is needed to properly couple large out-of-plane and in-plane deformations. Depending on the loading, this nonlinear coupling mechanism manifests itself in a distinct manner in compression- and tension-dominated sections of the structure. Under significant compression, nonlinear analysis is needed to accurately predict loss of stability and postbuckled deformation. Under significant tension, the nonlinear effects account for suppression of the out-of-plane deformation due to in-plane stretching. By comparing the present results with the previously

  3. Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft

    SciTech Connect

    Vargas-Rojas, Erik Camarena-Arellano, Diego Hernández-Moreno, Hilario

    2014-05-15

    An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals.

  4. Efficacy of aerial spray applications using fuselage booms on Air Force C-130H aircraft against mosquitoes and biting midges.

    PubMed

    Breidenbaugh, Mark S; Haagsma, Karl A; Wojcik, George M; De Szalay, Ferenc A

    2009-12-01

    The effectiveness of a novel fuselage boom configuration was tested with flat-fan nozzles on U.S. Air Force C-130H aircraft to create ultra-low volume sprays to control mosquitoes (Culicidae) and biting midges (Ceratopogonidae). The mortality of mosquitoes and biting midges in bioassay cages and natural populations, using the organophosphate adulticide, naled, was measured. Mosquitoes in bioassay cages had 100% mortality at 639 m downwind in all single-pass spray trials, and most trials had >90% mortality up to 1491 m downwind. Mosquito mortality was negatively correlated with distance from the spray release point (r2 = 0.38, P < 0.001). The volume median diam of droplets collected was 44 tm at 213 m and decreased to 11 microm at 2130 m downwind of the release point. Droplet density decreased from an average of 18.4 drops/cm2 at 213 m to 2 drops/cm2 at 2130 m. Droplet densities of 10-18 droplets/cm2 were recorded at sampling stations with high mosquito mortality rates (>90%). In wide-area operational applications, numbers of mosquitoes from natural populations 1 wk postspray were 83% (range 55%-95%), lower than prespray numbers (P < 0.05). Biting midge numbers were reduced by 86% (range 53%-97%) on average (P = 0.051) after 7 days. The results of these field trials indicate that the fuselage boom configuration on C-130H aircraft are an effective method to conduct large-scale aerial sprays during military operations and public health emergencies. PMID:20099594

  5. Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure. Part 1; Ultimate Design Loads

    NASA Technical Reports Server (NTRS)

    Przekop, Adam; Jegley, Dawn C.; Lovejoy, Andrew E.; Rouse, Marshall; Wu, Hsi-Yung T.

    2016-01-01

    The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses finite element analysis and testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part I of the paper considers the five most critical load conditions, which are internal pressure only and positive and negative g-loads with and without internal pressure. Analysis results are compared with measurements acquired during testing. Performance of the test article is found to be closely aligned with predictions and, consequently, able to support the hybrid wing body design loads in pristine and barely visible impact damage conditions.

  6. Fuselage Boundary Layer Ingestion Propulsion Applied to a Thin Haul Commuter Aircraft for Optimal Efficiency

    NASA Technical Reports Server (NTRS)

    Mikic, Gregor Veble; Stoll, Alex; Bevirt, JoeBen; Grah, Rok; Moore, Mark D.

    2016-01-01

    Theoretical and numerical aspects of aerodynamic efficiency of propulsion systems are studied. Focus is on types of propulsion that closely couples to the aerodynamics of the complete vehicle. We discuss the effects of local flow fields, which are affected both by conservative flow acceleration as well as total pressure losses, on the efficiency of boundary layer immersed propulsion devices. We introduce the concept of a boundary layer retardation turbine that helps reduce skin friction over the fuselage. We numerically investigate efficiency gains offered by boundary layer and wake interacting devices. We discuss the results in terms of a total energy consumption framework and show that efficiency gains offered depend on all the elements of the propulsion system.

  7. Volumetric pattern analysis of fuselage-mounted airborne antennas. Ph.D. Thesis; [prediction analysis techniques for antenna radiation patterns of microwave antennas on commercial aircraft

    NASA Technical Reports Server (NTRS)

    Yu, C. L.

    1976-01-01

    A volumetric pattern analysis of fuselage-mounted airborne antennas at high frequencies was investigated. The primary goal of the investigation was to develop a numerical solution for predicting radiation patterns of airborne antennas in an accurate and efficient manner. An analytical study of airborne antenna pattern problems is presented in which the antenna is mounted on the fuselage near the top or bottom. Since this is a study of general-type commercial aircraft, the aircraft was modeled in its most basic form. The fuselage was assumed to be an infinitely long perfectly conducting elliptic cylinder in its cross-section and a composite elliptic cylinder in its elevation profile. The wing, cockpit, stabilizers (horizontal and vertical) and landing gear are modeled by "N" sided bent or flat plates which can be arbitrarily attached to the fuselage. The volumetric solution developed utilizes two elliptic cylinders, namely, the roll plane and elevation plane models to approximate the principal surface profile (longitudinal and transverse) at the antenna location. With the belt concept and the aid of appropriate coordinate system transformations the solution can be used to predict the volumetric patterns of airborne antennas in an accurate and efficient manner. Applications of this solution to various airborne antenna problems show good agreement with scale model measurements. Extensive data are presented for a microwave landing antenna system.

  8. Automation of disbond detection in aircraft fuselage through thermal image processing

    NASA Technical Reports Server (NTRS)

    Prabhu, D. R.; Winfree, W. P.

    1992-01-01

    A procedure for interpreting thermal images obtained during the nondestructive evaluation of aircraft bonded joints is presented. The procedure operates on time-derivative thermal images and resulted in a disbond image with disbonds highlighted. The size of the 'black clusters' in the output disbond image is a quantitative measure of disbond size. The procedure is illustrated using simulation data as well as data obtained through experimental testing of fabricated samples and aircraft panels. Good results are obtained, and, except in pathological cases, 'false calls' in the cases studied appeared only as noise in the output disbond image which was easily filtered out. The thermal detection technique coupled with an automated image interpretation capability will be a very fast and effective method for inspecting bonded joints in an aircraft structure.

  9. Modelling Strategies for Predicting the Residual Strength of Impacted Composite Aircraft Fuselages

    NASA Astrophysics Data System (ADS)

    Lachaud, Frederic; Espinosa, Christine; Michel, Laurent; Rahme, Pierre; Piquet, Robert

    2015-12-01

    Aeronautic Certification rules established for the metallic materials are not convenient for the composite structures concerning the resistance against impact. The computer-based design is a new methodology that is thought about to replace the experimental tests. It becomes necessary for numerical methods to be robust and predictive for impact. Three questions are addressed in this study: (i) can a numerical model be "mechanically intrinsic" to predict damage after impact, (ii) can this model be the same for a lab sample and a large structure, and (iii) can the numerical model be predictive enough to predict the Compression After Impact (CAI)? Three different computational strategies are used and compared: a Cohesive Model (CM), a Continuous Damage Model (CDM) coupling failure modes and damage, and a Mixed Methodology (MM) using the CDM for delamination initiation and the CM for cracks propagation. The first attempts to use the Smooth Particle Hydrodynamics method are presented. Finally, impact on a fuselage is modelled and a numerical two-stage strategy is developed to predict the CAI.

  10. Reduction of Aircraft Cruise Drag By Using Boundary Layer Heating To Minimize Fuselage Skin Friction

    NASA Technical Reports Server (NTRS)

    Kramer, Brian R.

    1997-01-01

    The data reduction and results of the F-15B Flight Test Fixture experiment conducted at NASA Dryden are discussed. In addition, the feasibility of using the Orbital Sciences L-1011 was studied and a cost estimate prepared. Initial discussions have begun with Edwards Flight Research to explore the possibility of using their T-39 aircraft for the second flight experiment.

  11. An artifical corrosion protocol for lap-splices in aircraft skin

    NASA Technical Reports Server (NTRS)

    Shaw, Bevil J.

    1994-01-01

    This paper reviews the progress to date to formulate an artificial corrosion protocol for the Tinker AFB C/KC-135 Corrosion Fatigue Round Robin Test Program. The project has provided new test methods to faithfully reproduce the corrosion damage within a lap-splice by accelerated means, the rationale for a new laboratory test environment, and a means for corrosion damage quantification. The approach is pragmatic and the resulting artificial corrosion protocol lays the foundation for future research in the assessment of aerospace alloys. The general means for quantification of corrosion damage has been presented in a form which can be directly applied to structural integrity calculations.

  12. Noise Reduction in an Aircraft Fuselage Model Using Active Trim Panels

    NASA Technical Reports Server (NTRS)

    Silcox, Richard J.; Lyle, Karen H.

    1996-01-01

    An experiment was conducted to evaluate the use of force actuators on a model aircraft interior trim panel as the control element for active control of interior noise. The trim panel, designed specifically for this study, was constructed in three large identical sections and hard mounted to the ring frames of the primary structure. Piezoceramic actuators were bonded to the outer surface of the trim panels. Studies of the interior pressure response due to both the primary source alone and control sources alone were conducted as well as the control cases. A single acoustic loudspeaker, centered at the axial midpoint, generated the acoustic field to be controlled.

  13. Evaluation of the concept of pressure proof testing fuselage structures

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Orringer, Oscar

    1991-01-01

    The FAA and NASA have recently completed independent technical evaluations of the concept of pressure proof testing the fuselage of commercial transport airplanes. The results of these evaluations are summarized. The objectives of the evaluations were to establish the potential benefit of the pressure proof test, to quantify the most desirable proof test pressure, and to quantify the required proof test interval. The focus of the evaluations was on multiple-site cracks extending from adjacent rivet holes of a typical fuselage longitudinal lap splice joint. The FAA and NASA do not support pressure proof testing the fuselage of aging commercial transport aircraft. The argument against proof testing is as follows: (1) a single proof test does not insure an indefinite life; therefore, the proof test must be repeated at regular intervals; (2) for a proof factor of 1.33, the required proof test interval must be below 300 flights to account for uncertainties in the evaluation; (3) conducting the proof test at a proof factor of 1.5 would considerably exceed the fuselage design limit load; therefore, it is not consistent with accepted safe practices; and (4) better safety can be assured by implementing enhanced nondestructive inspection requirements, and adequate reliability can be achieved by an inspection interval several times longer than the proof test interval.

  14. Multifrequency Eddy Current Inspection of Corrosion in Clad Aluminum Riveted Lap Joints and Its Effect on Fatigue Life

    SciTech Connect

    Okafor, A. C.; Natarajan, S.

    2007-03-21

    Aging aircraft are prone to corrosion damage and fatigue cracks in riveted lap joints of fuselage skin panels. This can cause catastrophic failure if not detected and repaired. Hence detection of corrosion damage and monitoring its effect on structural integrity are essential. This paper presents multifrequency eddy current (EC) inspection of corrosion damage and machined material loss defect in clad A1 2024-T3 riveted lap joints and its effect on fatigue life. Results of eddy current inspection, corrosion product removal and fatigue testing are presented.

  15. Multifrequency Eddy Current Inspection of Corrosion in Clad Aluminum Riveted Lap Joints and Its Effect on Fatigue Life

    NASA Astrophysics Data System (ADS)

    Okafor, A. C.; Natarajan, S.

    2007-03-01

    Aging aircraft are prone to corrosion damage and fatigue cracks in riveted lap joints of fuselage skin panels. This can cause catastrophic failure if not detected and repaired. Hence detection of corrosion damage and monitoring its effect on structural integrity are essential. This paper presents multifrequency eddy current (EC) inspection of corrosion damage and machined material loss defect in clad A1 2024-T3 riveted lap joints and its effect on fatigue life. Results of eddy current inspection, corrosion product removal and fatigue testing are presented.

  16. Lake Michigan and Lake Superior air quality: The 1994-2003 LADCO Aircraft Project (LAP)

    NASA Astrophysics Data System (ADS)

    Foley, T. A.; Betterton, E. A.; Jacko, R.; Hillery, J.

    2011-12-01

    The goal of the 1994 to 2003 LADCO Airplane Project (LAP) was to study ozone formation over Lake Michigan so that equitable regional control strategies could be devised. During the ten year LAP campaign, a total of 328 flights were flown on 81 days over Lake Michigan and its southern and western boundaries. LAP also monitored air quality over Lake Superior and other areas in the Midwestern and southern United States. From 2001 to 2003, 117 flights were conducted over Lake Superior, Isle Royale National Park, Painted Rocks National Lakeshore and the Seeney National Wildlife Refuge in Michigan. 63 flights were conducted over St. Louis and 58 flights over the Dolly Sods Wilderness Area in West Virginia. We are looking for collaborators to help us analyze this vast data archive. Our first paper (Atmospheric Environment 45 (2011) 3192-3202) documented the project and presented results of our ozone analysis. Our results support the hypothesis of Dye et al. (1995), who found that the atmosphere over Lake Michigan is stable in the summer due to the air water temperature difference, which creates an efficient reaction chamber for ozone formation. They also hypothesized that the southwest winds characteristic of ozone-conducive conditions transport ozone further north over the lake before it crosses the shoreline onto land. We found that below 200 m above the lake, ozone formation is VOC-limited in the morning and becomes NOx limited in the afternoon. Above 200 m, ozone formation is NOx-limited throughout the day. The onshore NOx and VOC diurnal cycles peak during the early morning rush hour and are clearly linked to traffic patterns. Over the lake, VOC and NOy concentrations peak during the mid-morning rather than the early morning, supporting the hypothesis that the land breeze transports VOC and NOy over the lake. The diurnal NOx pattern over Lake Michigan is less clearly defined than the VOC pattern possibly as a result of emissions from five coal-burning power plants

  17. Lapping slurry

    DOEpatents

    Simandl, R.F.; Upchurch, V.S.; Leitten, M.E.

    1999-01-05

    Improved lapping slurries provide for easier and more thorough cleaning of alumina work pieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid. 1 fig.

  18. Lapping slurry

    DOEpatents

    Simandl, Ronald F.; Upchurch, Victor S.; Leitten, Michael E.

    1999-01-01

    Improved lapping slurries provide for easier and more thorough cleaning of alumina workpieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid.

  19. The Influence of Feedback on the Aeroelastic Behavior of Tilt Proprotor Aircraft Including the Effects of Fuselage Motion

    NASA Technical Reports Server (NTRS)

    Curtiss, H. C., Jr.; Komatsuzaki, T.; Traybar, J. J.

    1979-01-01

    The influence of single loop feedbacks to improve the stability of the system are considered. Reduced order dynamic models are employed where appropriate to promote physical insight. The influence of fuselage freedom on the aeroelastic stability, and the influence of the airframe flexibility on the low frequency modes of motion relevant to the stability and control characteristics of the vehicle were examined.

  20. The vibro-acoustic response and analysis of a full-scale aircraft fuselage section for interior noise reduction.

    PubMed

    Herdic, Peter C; Houston, Brian H; Marcus, Martin H; Williams, Earl G; Baz, Amr M

    2005-06-01

    The surface and interior response of a Cessna Citation fuselage section under three different forcing functions (10-1000 Hz) is evaluated through spatially dense scanning measurements. Spatial Fourier analysis reveals that a point force applied to the stiffener grid provides a rich wavenumber response over a broad frequency range. The surface motion data show global structural modes (approximately < 150 Hz), superposition of global and local intrapanel responses (approximately 150-450 Hz), and intrapanel motion alone (approximately > 450 Hz). Some evidence of Bloch wave motion is observed, revealing classical stop/pass bands associated with stiffener periodicity. The interior response (approximately < 150 Hz) is dominated by global structural modes that force the interior cavity. Local intrapanel responses (approximately > 150 Hz) of the fuselage provide a broadband volume velocity source that strongly excites a high density of interior modes. Mode coupling between the structural response and the interior modes appears to be negligible due to a lack of frequency proximity and mismatches in the spatial distribution. A high degree-of-freedom finite element model of the fuselage section was developed as a predictive tool. The calculated response is in good agreement with the experimental result, yielding a general model development methodology for accurate prediction of structures with moderate to high complexity. PMID:16018470

  1. Fuselage upwash effects on RSRA rotor systems

    NASA Technical Reports Server (NTRS)

    Cowan, J.; Dadone, L.

    1985-01-01

    The effects of RSRA fuselage configurations on rotor performance and loads have been quantified analytically by means of currently available potential flow and rotor analysis. Four configurations of the Rotor Systems Research Aircraft (RSRA) were considered in this study. They were: (1) fuselage alone (conventional helicopter); (2) fuselage with auxiliary propulsion; (3) fuselage with wings (auxiliary lift); and (4) fuselage with both auxiliary lift propulsion. The rotor system investigated was identical to a CH-47D front rotor except that it had four instead of three blades. Two scaled-down versions of the same rotor were also analyzed to determine the effect of rotor scale on the fuselage upwash effects. The flight conditions considered for the upwash study are discussed. The potential flow models for the RSRA configuration, with and without the wings and the auxiliary propulsion system, are presented. The results of fuselage/wing/propulsion system upwash on performance and loads are also presented.

  2. Laboratory study of the effects of sidewall treatment, source directivity and temperature on the interior noise of a light aircraft fuselage

    NASA Technical Reports Server (NTRS)

    Heitman, K. E.; Mixson, J. S.

    1986-01-01

    This paper describes a laboratory study of add-on {coustic treatments for a twin-engine, propeller-driven aircraft fuselage. The sound source was a pneumatic-driver, with attached horn to simulate propeller noise distribution, powered by a white noise signal. Treatments included a double-wall, production-line treatment and various fiberglass and lead-vinyl treatments. Insertion losses, space-averaged across six interior microphone positions, were used to evaluate the treatments. In addition, the effects of sound source angle and ambient temperature on interior sound pressure level are presented. The sound source angle is shown to have a significant effect on one-third octave band localized sound pressure level. While changes in ambient temperature are shown to have little effect on one-third octave band localized sound pressure level, the change in narrowband localized sound pressure level may be dramatic.

  3. 14 CFR 25.783 - Fuselage doors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuselage doors. 25.783 Section 25.783 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Personnel and Cargo Accommodations § 25.783 Fuselage doors. (a) General....

  4. Analytical study of interior noise control by fuselage design techniques on high-speed, propeller-driven aircraft

    NASA Technical Reports Server (NTRS)

    Revell, J. D.; Balena, F. J.; Koval, L. R.

    1980-01-01

    The acoustical treatment mass penalties required to achieve an interior noise level of 80 dBA for high speed, fuel efficient propfan-powered aircraft are determined. The prediction method used is based on theory developed for the outer shell dynamics, and a modified approach for add-on noise control element performance. The present synthesis of these methods is supported by experimental data. Three different sized aircraft are studied, including a widebody, a narrowbody and a business sized aircraft. Noise control penalties are calculated for each aircraft for two kinds of noise control designs: add-on designs, where the outer wall structure cannot be changed, and advanced designs where the outer wall stiffness level and the materials usage can be altered. For the add-on designs, the mass penalties range from 1.7 to 2.4 percent of the takeoff gross weight (TOGW) of the various aircraft, similar to preliminary estimates. Results for advanced designs show significant reductions of the mass penalties. For the advanced aluminum designs the penalties are 1.5% of TOGW, and for an all composite aircraft the penalties range from 0.74 to 1.4% of TOGW.

  5. Advanced technology commercial fuselage structure

    NASA Technical Reports Server (NTRS)

    Ilcewicz, L. B.; Smith, P. J.; Walker, T. H.; Johnson, R. W.

    1991-01-01

    Boeing's program for Advanced Technology Composite Aircraft Structure (ATCAS) has focused on the manufacturing and performance issues associated with a wide body commercial transport fuselage. The primary goal of ATCAS is to demonstrate cost and weight savings over a 1995 aluminum benchmark. A 31 foot section of fuselage directly behind the wing to body intersection was selected for study purposes. This paper summarizes ATCAS contract plans and review progress to date. The six year ATCAS program will study technical issues for crown, side, and keel areas of the fuselage. All structural details in these areas will be included in design studies that incorporate a design build team (DBT) approach. Manufacturing technologies will be developed for concepts deemed by the DBT to have the greatest potential for cost and weight savings. Assembly issues for large, stiff, quadrant panels will receive special attention. Supporting technologies and mechanical tests will concentrate on the major issues identified for fuselage. These include damage tolerance, pressure containment, splices, load redistribution, post-buckled structure, and durability/life. Progress to date includes DBT selection of baseline fuselage concepts; cost and weight comparisons for crown panel designs; initial panel fabrication for manufacturing and structural mechanics research; and toughened material studies related to keel panels. Initial ATCAS studies have shown that NASA's Advanced Composite Technology program goals for cost and weight savings are attainable for composite fuselage.

  6. Flying wings / flying fuselages

    NASA Technical Reports Server (NTRS)

    Wood, Richard M.; Bauer, Steven X. S.

    2001-01-01

    The present paper has documented the historical relationships between various classes of all lifting vehicles, which includes the flying wing, all wing, tailless, lifting body, and lifting fuselage. The diversity in vehicle focus was to ensure that all vehicle types that map have contributed to or been influenced by the development of the classical flying wing concept was investigated. The paper has provided context and perspective for present and future aircraft design studies that may employ the all lifting vehicle concept. The paper also demonstrated the benefit of developing an understanding of the past in order to obtain the required knowledge to create future concepts with significantly improved aerodynamic performance.

  7. Effect on Drag of Longitudinal Positioning of Half-Submerged and Pylon-Mounted Douglas Aircraft Stores on a Fuselage with and without Cavities between Mach Numbers 0.9 and 1.8

    NASA Technical Reports Server (NTRS)

    Hoffman, Sherwood; Wolff, Austin L.

    1954-01-01

    The effect on drag of positioning symmetrically mounted Douglas Aircraft Company, Inc. stores in pairs on a parabolic fuselage of fineness ratio 10.0 has been determined by flight tests of rocket-propelled, zero-lift models through a range of Mach number from 0.9 to 1.8. The stores were mounted in half-submerged positions and on pylons and were tested in three longitudinal locations on the fuselage with the forward position being located at the maximum diameter of the fuselage. The effects on drag of removing the half-submerged stores or extending them outward on pylons also was investigated by tests of models with half-submerged-store cavities on the fuselage. Two pylons differing in airfoil section and thickness were tested at the forward position of the stores on the fuselage with cavities. The half-submerged stores gave the smallest drag increments, which were approximately equal regardless of their respective longitudinal locations. Removing the half-submerged stores to expose the cavities increased the drag increments from two to three times. For the pylon-mounted stores, the store in the midposition had less drag than in the forward or rear positions at supersonic speeds. Adding the half-submerged-store cavities to the pylon-mounted-store configurations reduced the drag at the rear position between Mach numbers 0.95 and 1.50 and increased the drag at the midposition throughout the speed range. Changing from the 6-percent-thick flat pylon to the 10-percent-thick airfoil pylon increased the total drag slightly above Mach number 1.10. Good agreement was obtain& between the experimental and theoretical interference drag coefficients for the pylon-mounted stores (without fuselage cavities} in the three longitudinal locations tested at Mach numbers 1.2 and 1.5.

  8. Aircraft

    DOEpatents

    Hibbs, B.D.; Lissaman, P.B.S.; Morgan, W.R.; Radkey, R.L.

    1998-09-22

    This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing`s top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gases for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well. 31 figs.

  9. Aircraft

    DOEpatents

    Hibbs, Bart D.; Lissaman, Peter B. S.; Morgan, Walter R.; Radkey, Robert L.

    1998-01-01

    This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing's top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gasses for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well.

  10. The characterization of widespread fatigue damage in fuselage structure

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Willard, Scott A.; Miller, Matthew

    1994-01-01

    The characteristics of widespread fatigue damage (WSFD) in fuselage riveted structure were established by detailed nondestructive and destructive examinations of fatigue damage contained in a full size fuselage test article. The objectives of this were to establish an experimental data base for validating emerging WSFD analytical prediction methodology and to identify first order effects that contribute to fatigue crack initiation and growth. Detailed examinations were performed on a test panel containing four bays of a riveted lap splice joint. The panel was removed from a full scale fuselage test article after receiving 60,000 full pressurization cycles. The results of in situ examinations document the progression of fuselage skin fatigue crack growth through crack linkup. Detailed tear down examinations and fractography of the lap splice joint region revealed fatigue crack initiation sites, crack morphology, and crack linkup geometry. From this large data base, distributions of crack size and locations are presented and discussions of operative damage mechanisms are offered.

  11. Effects of boundary layer refraction and fuselage scattering on fuselage surface noise from advanced turboprop propellers

    NASA Technical Reports Server (NTRS)

    Mcaninch, G. L.; Rawls, J. W., Jr.

    1984-01-01

    An acoustic disturbance's propagation through a boundary layer is discussed with a view to the analysis of the acoustic field generated by a propfan rotor incident to the fuselage of an aircraft. Applying the parallel flow assumption, the resulting partial differential equations are reduced to an ordinary acoustic pressure differential equation by means of the Fourier transform. The methods used for the solution of this equation include those of Frobenius and of analytic continuation; both yield exact solutions in series form. Two models of the aircraft fuselage-boundary layer system are considered, in the first of which the fuselage is replaced by a flat plate and the acoustic field is assumed to be two-dimensional, while in the second the fuselage is a cylinder in a fully three-dimensional acoustic field. It is shown that the boundary layer correction improves theory-data comparisons over simple application of a pressure-doubling rule at the fuselage.

  12. Investigation of fuselage acoustic treatment for a twin-engine turboprop aircraft in flight and laboratory tests

    NASA Technical Reports Server (NTRS)

    Mixson, J. S.; Oneal, R. L.; Grosveld, F. W.

    1984-01-01

    A flight and laboratory study of sidewall acoustic treatment for cabin noise control is described. In flight, cabin noise levels were measured at six locations with three treatment configurations. Noise levels from narrow-band analysis are reduced to one-third octave format and used to calculate insertion loss, IL, defined as the reduction of interior noise associated with the addition of a treatment. Laboratory tests used a specially constructed structural panel modeled after the propeller plane section of the aircraft sidewall, and acoustic treatments representing those used in flight. Lab measured transmission loss and absorption values were combined using classical acoustic procedures to obtain a prediction of IL. Comparison with IL values measured in flight for the boundary layer component of the noise indicated general agreement.

  13. Dynamic thermal tomography for nondestructive inspection of aging aircraft

    SciTech Connect

    Del Grande, N.K.; Dolan, K.W.; Durbin, P.F.; Gorvad, M.R.; Shapiro, A.B.

    1993-11-01

    The authors apply dual-band infrared (DBIR) imaging as a dynamic thermal tomography tool for wide area inspection of a Boeing 737 aircraft and several Boeing KC-135 aircraft panels. The analyses are discussed in this report. After flash-heating the aircraft skin, they record synchronized DBIR images every 40 ms, from onset to 8 seconds after the heat flash. They analyze selective DBIR image ratios which enhance surface temperature contrast and remove surface-emissivity clutter. The Boeing 737 and KC-135 aircraft fuselage panels have varying percent thickness losses from corrosion. They established the correlation of percent thickness loss with surface temperature rise (above ambient) for a partially corroded F-18 wing box structure and several aluminum plates which had 6 to 60% thickness losses at milled flat-bottom hole sites. Based on this correlation, lap splice temperatures rise 1C per 24 {plus_minus} 5% material loss at 0.4 s after the heat flash. They tabulate and map corrosion-related percent thickness loss effects for the riveted Boeing 737, and the riveted Boeing KKC-135. They map the fuselage composite thermal inertia, based on the (inverse) slope of the surface temperature versus inverse square root of time. Composite thermal inertia maps characterized shallow skin defects within the lap splice at early times (< 0.3 s) and deeper skin defects within the lap splice at late times (> 0.4 s). Late time composite thermal inertia maps depict where corrosion-related thickness losses occur (e.g., on the inside of the Boeing 737 lap splice, beneath the galley and the latrine). Lap splice sites on a typical Boeing KC-135 panel with low composite thermal inertia values had high skin-thickness losses from corrosion.

  14. Dual-band infrared (DBIR) imaging inspections of Boeing 737 and KC-135 aircraft panels

    SciTech Connect

    Del Grande, N.K.; Dolan, K.W.; Durbin, P.F.; Gorvad, M.R.; Shapiro, A.B.

    1993-08-27

    We apply dual-band infrared (DBIR) imaging as a dynamic thermal tomography tool for wide area inspection of a Boeing 737 aircraft, and several Boeing KC-135 aircraft panels. Our analyses are discussed in this report. After flash-heating the aircraft skin, we record synchronized DBIR images every 40 ms, from onset to 8 seconds after the heat flash. We analyze selective DBIR image ratios which enhance surface temperature contrast and remove surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). The Boeing 737 and KC-135 aircraft fuselage panels have varying percent thickness losses from corrosion. We established the correlation of percent thickness loss with surface temperature rise (above ambient) for a partially corroded F-18 wing box structure and several aluminum reference panels. Based on this correlation, lap splice temperatures rise 1{degrees}C per 24 {plus_minus} 5 % material loss at 0.4 s after the heat flash. We show tables, charts and temperature maps of typical lap splice material losses for the riveted (and bonded) Boeing 737, and the riveted (but unbonded) Boeing KC-135. We map the fuselage composite thermal inertia, based on the (inverse) slope of the surface temperature versus inverse square root of time. Composite thermal inertia maps characterize shallow skin defects within the lap splice at early times (<0.3 s) and deeper skin defects within the lap splice at late times (>0.4 s). Late time composite thermal inertia maps depict where corrosion-related thickness losses occur. Lap splice sites on a typical Boeing KC-135 panel with low composite thermal inertia values had high skin-thickness losses from corrosion.

  15. Advanced tow placement of composite fuselage structure

    NASA Technical Reports Server (NTRS)

    Anderson, Robert L.; Grant, Carroll G.

    1992-01-01

    The Hercules NASA ACT program was established to demonstrate and validate the low cost potential of the automated tow placement process for fabrication of aircraft primary structures. The program is currently being conducted as a cooperative program in collaboration with the Boeing ATCAS Program. The Hercules advanced tow placement process has been in development since 1982 and was developed specifically for composite aircraft structures. The second generation machine, now in operation at Hercules, is a production-ready machine that uses a low cost prepreg tow material form to produce structures with laminate properties equivalent to prepreg tape layup. Current program activities are focused on demonstration of the automated tow placement process for fabrication of subsonic transport aircraft fuselage crown quadrants. We are working with Boeing Commercial Aircraft and Douglas Aircraft during this phase of the program. The Douglas demonstration panels has co-cured skin/stringers, and the Boeing demonstration panel is an intricately bonded part with co-cured skin/stringers and co-bonded frames. Other aircraft structures that were evaluated for the automated tow placement process include engine nacelle components, fuselage pressure bulkheads, and fuselage tail cones. Because of the cylindrical shape of these structures, multiple parts can be fabricated on one two placement tool, thus reducing the cost per pound of the finished part.

  16. Some comments on fuselage drag

    NASA Technical Reports Server (NTRS)

    Roskam, J.

    1975-01-01

    The following areas relating to fuselage drag are considered: (1) fuselage fineness - ratio and why and how this can be selected during preliminary design; (2) windshield drag; (3) skin roughness; and (4) research needs in the area of fuselage drag.

  17. Composite Fuselage Technology

    NASA Technical Reports Server (NTRS)

    Lagace, Paul A.

    1999-01-01

    Work was conducted over a ten-year period to address the central issue of damage in primary load-bearing aircraft composite structure, specifically fuselage structure. This included the three facets of damage resistance, damage tolerance, and damage arrest. Experimental, analytical, and numerical work was conducted in order to identify and better understand the mechanisms that control the structural behavior of fuselage structures in their response to the three aspects of damage. Furthermore, work was done to develop straightforward design methodologies that can be employed by structural designers in preliminary design stages to make intelligent choices concerning the material, layup, and structural configurations so that a more efficient structure with structural integrity can be designed and built. Considerable progress was made towards achieving these goals via this work. In regard to damage tolerance considerations, the following were identified as important effects: composite layup and associated orthotropy/structural anisotropy, specifics of initial local damage mechanisms, role of longitudinal versus hoop stress, and large deformation and associated geometric nonlinearity. Means were established to account for effects of radius and for the nonlinear response. In particular, nondimensional parameters were identified to characterize the importance of nonlinearity in the response of pressurized cylinders. This led to the establishment of a iso-nonlinear-error plot for reference in structural design. Finally, in the case of damage tolerance, the general approach of the original methodology to predict the failure pressure involving extending basic plate failure data by accounting for the local stress intensification was accomplished for the general case by accounting for the mechanisms noted by utilizing the capability of the STAGS finite element code and numerically calculating the local stress intensification for the particular configuration to be considered

  18. Composite fuselage shell structures research at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Shuart, Mark J.

    1992-01-01

    Fuselage structures for transport aircraft represent a significant percentage of both the weight and the cost of these aircraft primary structures. Composite materials offer the potential for reducing both the weight and the cost of transport fuselage structures, but only limited studies of the response and failure of composite fuselage structures have been conducted for transport aircraft. The behavior of these important primary structures must be understood, and the structural mechanics methodology for analyzing and designing these complex stiffened shell structures must be validated in the laboratory. The effects of local gradients and discontinuities on fuselage shell behavior and the effects of local damage on pressure containment must be thoroughly understood before composite fuselage structures can be used for commercial aircraft. This paper describes the research being conducted and planned at NASA LaRC to help understand the critical behavior or composite fuselage structures and to validate the structural mechanics methodology being developed for stiffened composite fuselage shell structure subjected to combined internal pressure and mechanical loads. Stiffened shell and curved stiffened panel designs are currently being developed and analyzed, and these designs will be fabricated and then tested at Langley to study critical fuselage shell behavior and to validate structural analysis and design methodology. The research includes studies of the effects of combined internal pressure and mechanical loads on nonlinear stiffened panel and shell behavior, the effects of cutouts and other gradient-producing discontinuities on composite shell response, and the effects of local damage on pressure containment and residual strength. Scaling laws are being developed that relate full-scale and subscale behavior of composite fuselage shells. Failure mechanisms are being identified and advanced designs will be developed based on what is learned from early results from

  19. Transport composite fuselage technology: Impact dynamics and acoustic transmission

    NASA Technical Reports Server (NTRS)

    Jackson, A. C.; Balena, F. J.; Labarge, W. L.; Pei, G.; Pitman, W. A.; Wittlin, G.

    1986-01-01

    A program was performed to develop and demonstrate the impact dynamics and acoustic transmission technology for a composite fuselage which meets the design requirements of a 1990 large transport aircraft without substantial weight and cost penalties. The program developed the analytical methodology for the prediction of acoustic transmission behavior of advanced composite stiffened shell structures. The methodology predicted that the interior noise level in a composite fuselage due to turbulent boundary layer will be less than in a comparable aluminum fuselage. The verification of these analyses will be performed by NASA Langley Research Center using a composite fuselage shell fabricated by filament winding. The program also developed analytical methodology for the prediction of the impact dynamics behavior of lower fuselage structure constructed with composite materials. Development tests were performed to demonstrate that the composite structure designed to the same operating load requirement can have at least the same energy absorption capability as aluminum structure.

  20. Variable Geometry Aircraft Wing Supported by Struts And/Or Trusses

    NASA Technical Reports Server (NTRS)

    Melton, John E. (Inventor); Dudley, Michael R. (Inventor)

    2016-01-01

    The present invention provides an aircraft having variable airframe geometry for accommodating efficient flight. The aircraft includes an elongated fuselage, an oblique wing pivotally connected with said fuselage, a wing pivoting mechanism connected with said oblique wing and said fuselage, and a brace operably connected between said oblique wing and said fuselage. The present invention also provides an aircraft having an elongated fuselage, an oblique wing pivotally connected with said fuselage, a wing pivoting mechanism connected with said oblique wing and said fuselage, a propulsion system pivotally connected with said oblique wing, and a brace operably connected between said propulsion system and said fuselage.

  1. Advanced Technology Composite Fuselage - Manufacturing

    NASA Technical Reports Server (NTRS)

    Wilden, K. S.; Harris, C. G.; Flynn, B. W.; Gessel, M. G.; Scholz, D. B.; Stawski, S.; Winston, V.

    1997-01-01

    The goal of Boeing's Advanced Technology Composite Aircraft Structures (ATCAS) program is to develop the technology required for cost-and weight-efficient use of composite materials in transport fuselage structure. Carbon fiber reinforced epoxy was chosen for fuselage skins and stiffening elements, and for passenger and cargo floor structures. The automated fiber placement (AFP) process was selected for fabrication of stringer-stiffened and sandwich skin panels. Circumferential and window frames were braided and resin transfer molded (RTM'd). Pultrusion was selected for fabrication of floor beams and constant-section stiffening elements. Drape forming was chosen for stringers and other stiffening elements cocured to skin structures. Significant process development efforts included AFP, braiding, RTM, autoclave cure, and core blanket fabrication for both sandwich and stiffened-skin structure. Outer-mold-line and inner-mold-line tooling was developed for sandwich structures and stiffened-skin structure. The effect of design details, process control and tool design on repeatable, dimensionally stable, structure for low cost barrel assembly was assessed. Subcomponent panels representative of crown, keel, and side quadrant panels were fabricated to assess scale-up effects and manufacturing anomalies for full-scale structures. Manufacturing database including time studies, part quality, and manufacturing plans were generated to support the development of designs and analytical models to access cost, structural performance, and dimensional tolerance.

  2. Crack Growth Simulation and Residual Strength Prediction in Airplane Fuselages

    NASA Technical Reports Server (NTRS)

    Chen, Chuin-Shan; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1999-01-01

    The objectives were to create a capability to simulate curvilinear crack growth and ductile tearing in aircraft fuselages subjected to widespread fatigue damage and to validate with tests. Analysis methodology and software program (FRANC3D/STAGS) developed herein allows engineers to maintain aging aircraft economically, while insuring continuous airworthiness, and to design more damage-tolerant aircraft for the next generation. Simulations of crack growth in fuselages were described. The crack tip opening angle (CTOA) fracture criterion, obtained from laboratory tests, was used to predict fracture behavior of fuselage panel tests. Geometrically nonlinear, elastic-plastic, thin shell finite element crack growth analyses were conducted. Comparisons of stress distributions, multiple stable crack growth history, and residual strength between measured and predicted results were made to assess the validity of the methodology. Incorporation of residual plastic deformations and tear strap failure was essential for accurate residual strength predictions. Issue related to predicting crack trajectory in fuselages were also discussed. A directional criterion, including T-stress and fracture toughness orthotropy, was developed. Curvilinear crack growth was simulated in coupon and fuselage panel tests. Both T-stress and fracture toughness orthotropy were essential to predict the observed crack paths. Flapping of fuselages were predicted. Measured and predicted results agreed reasonable well.

  3. Al-Li Alloy 1441 for Fuselage Applications

    NASA Technical Reports Server (NTRS)

    Bird, R. K.; Dicus, D. L.; Fridlyander, J. N.; Sandler, V. S.

    2000-01-01

    A cooperative investigation was conducted to evaluate Al-Cu-Mg-Li alloy 1441 for long service life fuselage applications. Alloy 1441 is currently being used for fuselage applications on the Russian Be-103 amphibious aircraft, and is expected to be used for fuselage skin on a new Tupolev business class aircraft. Alloy 1441 is cold-rollable and has several attributes that make it attractive for fuselage skin applications. These attributes include lower density and higher specific modulus with similar strength as compared to conventional Al-Cu-Mg alloys. Cold-rolled 1441 Al-Li sheet specimens were tested at NASA Langley Research Center (LaRC) and at the All-Russia Institute of Aviation Materials (VIAM) in Russia to evaluate tensile properties, fracture toughness, impact resistance, fatigue life and fatigue crack growth rate. In addition, fuselage panels were fabricated by Tupolev Design Bureau (TDB) using 1441 skins and Al-Zn-Mg-Cu alloy stiffeners. The panels were subjected to cyclic pressurization fatigue tests at TDB and at LaRC to simulate fuselage pressurization/depressurization during aircraft service. This paper discusses the results from this investigation.

  4. Performance of fuselage pressure structure

    NASA Astrophysics Data System (ADS)

    Maclin, James R.

    1992-07-01

    There are currently more than 1,000 Boeing airplanes around the world over 20 years old. That number is expected to double by the year 1995. With these statistics comes the reality that structural airworthiness will be in the forefront of aviation issues well into the next century. The results of previous and recent test programs Boeing has implemented to study the structural performance of older airplanes relative to pressurized fuselage sections are described. Included in testing were flat panels with multiple site damage (MSD), a full-scale 737 and 2 747s as well as panels representing a 737 and 777, and a generic aircraft in large pressure-test fixtures. Because damage is a normal part of aging, focus is on the degree to which structural integrity is maintained after failure or partial failure of any structural element, including multiple site damage (MSD), and multiple element damage (MED).

  5. Dual-band infrared imaging for quantitative corrosion detection in aging aircraft

    SciTech Connect

    Del Grande, N.K.

    1993-12-31

    Aircraft skin thickness-loss from corrosion has been measured using dual-band infrared (DBIR) imaging on a flash-heated Boeing 737 fuselage structure. The authors mapped surface temperature differences of 0.2 to 0.6 C for 5 to 14 % thickness losses within corroded lap splices at 0.4 seconds after the heat flash. The procedure mapped surface temperature differences at sites without surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). They established the correlation of percent thickness loss with surface temperature rise using a partially corroded F-18 wing box and several aluminum panels which had thickness losses from milled flat-bottom holes. The authors mapped the lap splice composite thermal inertia, (k{rho}c){sup 1/2}, which characterized shallow skin defects within the lap splice at early times (<0.3 s) and deeper skin defects within the lap splice at late times (>0.4 s). Corrosion invaded the inside of the Boeing 737 lap splice, beneath the galley and the latrine, where they observed ``pillowing`` from volume build-up of corrosion by-products.

  6. Dual-band infrared imaging for quantitative corrosion detection in aging aircraft

    SciTech Connect

    Del Grande, N.K.

    1993-11-01

    Aircraft skin thickness-loss from corrosion has been measured using dual-band infrared (DBIR) imaging on a flash-heated Boeing 737 fuselage structure. We mapped surface temperature differences of 0.2 to 0.6 {degrees}C for 5 to 14% thickness losses within corroded lap splices at 0.4 seconds after the heat flash. Our procedure mapped surface temperature differences at sites without surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). We established the correlation of percent thickness loss with surface temperature rise using a partially corroded F-18 wing box and several aluminum panels which had thickness losses from milled flat-bottom holes. We mapped the lap splice composite thermal inertia, (kpc){sup {1/2}}, which characterized shallow skin defects within the lap splice at early times (<0.3 s) and deeper skin defects within the lap splice at late times (>0.4 s). Corrosion invaded the inside of the Boeing 737 lap splice, beneath the galley and the latrine, where we observed ``pillowing`` from volume build-up of corrosion by-products.

  7. Oblique-wing supersonic aircraft

    NASA Technical Reports Server (NTRS)

    Jones, R. T. (Inventor)

    1976-01-01

    An aircraft including a single fuselage having a main wing and a horizontal stabilizer airfoil pivotally attached at their centers to the fuselage is described. The pivotal attachments allow the airfoils to be yawed relative to the fuselage for high speed flight, and to be positioned at right angles with respect to the fuselage during takeoff, landing, and low speed flight. The main wing and the horizontal stabilizer are upwardly curved from their center pivotal connections towards their ends to form curvilinear dihedrals.

  8. Advanced fiber placement of composite fuselage structures

    NASA Technical Reports Server (NTRS)

    Anderson, Robert L.; Grant, Carroll G.

    1991-01-01

    The Hercules/NASA Advanced Composite Technology (ACT) program will demonstrate the low cost potential of the automated fiber placement process. The Hercules fiber placement machine was developed for cost effective production of composite aircraft structures. The process uses a low cost prepreg tow material form and achieves equivalent laminate properties to structures fabricated with prepreg tape layup. Fiber placement demonstrations planned for the Hercules/NASA program include fabrication of stiffened test panels which represent crown, keel, and window belt segments of a typical transport aircraft fuselage.

  9. Double-sided fiber laser beam welding process of T-joints for aluminum aircraft fuselage panels: Filler wire melting behavior, process stability, and their effects on porosity defects

    NASA Astrophysics Data System (ADS)

    Tao, Wang; Yang, Zhibin; Chen, Yanbin; Li, Liqun; Jiang, Zhenguo; Zhang, Yunlong

    2013-11-01

    Aluminum alloy T-joints for aircraft fuselage panels were fabricated by double-sided fiber laser beam welding with filler wire, and the influence of the wire feeding posture on the welding process stability was investigated. A CMOS high speed video system was used to observe the wire melting behavior and the weld pool dynamics in real time during the welding process by using a bandpass red laser with an emission wavelength of 808 nm as backlight source to illuminate the welding zone. The weld porosity defects were analyzed by X-ray radiography. The effects of wire feeding posture on the wire melting behavior, process stability, and porosity defects were investigated. The experimental results indicated that three distinct filler material transfer modes were identified under different wire feeding positions: liquid bridge transfer mode, droplet transfer mode, and spreading transfer mode. The liquid bridge transfer mode could guarantee a stable welding process, and result in the lowest porosity. Compared with wire feeding in the leading direction, the process was not stable and porosity increased when wire feeding in the trailing direction. Increased in the wire feeding angle was disadvantage for pores to escape from the weld molten pool, meanwhile, it made the welding process window smaller due to increasing the centering precision requirement for adjusting the filler wire.

  10. Structural Concepts Study of Non-circular Fuselage Configurations

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivel

    1996-01-01

    A preliminary study of structural concepts for noncircular fuselage configurations is presented. For an unconventional flying-wing type aircraft, in which the fuselage is inside the wing, multiple fuselage bays with non-circular sections need to be considered. In a conventional circular fuselage section, internal pressure is carried efficiently by a thin skin via hoop tension. If the section is non-circular, internal pressure loads also induce large bending stresses. The structure must also withstand additional bending and compression loads from aerodynamic and gravitational forces. Flat and vaulted shell structural configurations for such an unconventional, non-circular pressurized fuselage of a large flying-wing were studied. A deep honeycomb sandwich-shell and a ribbed double-wall shell construction were considered. Combinations of these structural concepts were analyzed using both analytical and simple finite element models of isolated sections for a comparative conceptual study. Weight, stress, and deflection results were compared to identify a suitable configuration for detailed analyses. The flat sandwich-shell concept was found preferable to the vaulted shell concept due to its superior buckling stiffness. Vaulted double-skin ribbed shell configurations were found to be superior due to their weight savings, load diffusion, and fail-safe features. The vaulted double-skin ribbed shell structure concept was also analyzed for an integrated wing-fuselage finite element model. Additional problem areas such as wing-fuselage junction and pressure-bearing spar were identified.

  11. Aero Commander in flight - Upswept fuselage study

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The NASA Flight Research Center's Aero Commander 680F is shown in flight with tufts attached to the side and bottom sections of the aircraft. These were placed on the aircraft for a Upswept Fuselage Study to see if the flow separated on the aft section of a small aircraft for comparison of data acquired from a large cargo-type aircraft with an upswept aft section. The photo of the tufts demonstrates that the flow is attached with no turbulence present. (Note the straight lines of tufts). The Aero Commander was used both for support and as a research aircraft. Among other uses, it was flown to outlying dry lakebeds, used as emergency landing sites, before X-15 flights. It could reach the lakebeds quickly and land on the hard-packed surfaces to ensure they were not soft from rainfall or some other cause. Between 1964 and 1966, the Flight Research Center used the aircraft in the Aviation Safety and Operating Problems Program to evaluate the aerodynamics of various light aircraft and to define possible technological improvements. The Aero Commander left what had become the Dryden Flight Research Center on March 14, 1979, and was transferred to the Customs Air Branch in San Diego. The Aero Commander 680F (N6297), built by the Aero Commander Company of Bethany, Oklahoma, is a pressurized five-place aircraft that is powered by two 380-horsepower reciprocating engines built by Lycoming Company. The fuselage length is 24.2 feet with a wing span of 35.98 feet.

  12. Fuselage shell and cavity response measurements on a DC-9 test section

    NASA Technical Reports Server (NTRS)

    Simpson, M. A.; Mathur, G. P.; Cannon, M. R.; Tran, B. N.; Burge, P. L.

    1991-01-01

    A series of fuselage shell and cavity response measurements conducted on a DC-9 aircraft test section are described. The objectives of these measurements were to define the shell and cavity model characteristics of the fuselage, understand the structural-acoustic coupling characteristics of the fuselage, and measure the response of the fuselage to different types of acoustic and vibration excitation. The fuselage was excited with several combinations of acoustic and mechanical sources using interior and exterior loudspeakers and shakers, and the response to these inputs was measured with arrays of microphones and accelerometers. The data were analyzed to generate spatial plots of the shell acceleration and cabin acoustic pressure field, and corresponding acceleration and pressure wavenumber maps. Analysis and interpretation of the spatial plots and wavenumber maps provided the required information on modal characteristics, structural-acoustic coupling, and fuselage response.

  13. Study for prediction of rotor/wake/fuselage interference. Part 2: Program users guide

    NASA Technical Reports Server (NTRS)

    Clark, D. R.; Maskew, B.

    1985-01-01

    A method was developed which permits the fully coupled calculation of fuselage and rotor airloads for typical helicopter configurations in forward flight. To do this, an iterative solution is carried out based on a conventional panel representation of the fuselage and a blade element representation of the rotor where fuselage and rotor singularity strengths are determined simultaneously at each step and the rotor wake is allowed to relax (deform) in response to changes in rotor wake loading and fuselage presence. On completion of the iteration, rotor loading and inflow, fuselage singularity strength (and, hence, pressure and velocity distributions) and rotor wake are all consistent. The results of a fully coupled calculation of the flow around representative helicopter configurations are presented. The effect of fuselage components on the rotor flow field and the overall wake structure is discussed as well as the aerodynamic interference between the different parts of the aircraft. Details of the computer program are given.

  14. Study for prediction of rotor/wake/fuselage interference, part 1

    NASA Technical Reports Server (NTRS)

    Clark, D. R.; Maskew, B.

    1985-01-01

    A method was developed which allows the fully coupled calculation of fuselage and rotor airloads for typical helicopter configurations in forward flight. To do this, an iterative solution is carried out based on a conventional panel representation of the fuselage and a blade element representation of the rotor where fuselage and rotor singularity strengths are determined simultaneously at each step and the rotor wake is allowed to relax (deform) in response to changes in rotor wake loading and fuselage presence. On completion of the iteration, rotor loading and inflow, fuselage singularity strength (and, hence, pressure and velocity distributions) and rotor wake are all consistent. The results of a fully coupled calculation of the flow around representative helicopter configurations are presented. The effect of fuselage components on the rotor flow field and the overall wake structure is detailed and the aerodynamic interference between the different parts of the aircraft is discussed.

  15. 6. Detail of forward fuselage showing open cockpit hatch and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Detail of forward fuselage showing open cockpit hatch and ladder. View to southeast. - Offutt Air Force Base, Looking Glass Airborne Command Post, Looking Glass Aircraft, On Operational Apron covering northeast half of Project Looking Glass Historic District, Bellevue, Sarpy County, NE

  16. Advanced Technology Composite Fuselage - Materials and Processes

    NASA Technical Reports Server (NTRS)

    Scholz, D. B.; Dost, E. F.; Flynn, B. W.; Ilcewicz, L. B.; Nelson, K. M.; Sawicki, A. J.; Walker, T. H.; Lakes, R. S.

    1997-01-01

    The goal of Boeing's Advanced Technology Composite Aircraft Structures (ATCAS) program was to develop the technology required for cost and weight efficient use of composite materials in transport fuselage structure. This contractor report describes results of material and process selection, development, and characterization activities. Carbon fiber reinforced epoxy was chosen for fuselage skins and stiffening elements and for passenger and cargo floor structures. The automated fiber placement (AFP) process was selected for fabrication of monolithic and sandwich skin panels. Circumferential frames and window frames were braided and resin transfer molded (RTM'd). Pultrusion was selected for fabrication of floor beams and constant section stiffening elements. Drape forming was chosen for stringers and other stiffening elements. Significant development efforts were expended on the AFP, braiding, and RTM processes. Sandwich core materials and core edge close-out design concepts were evaluated. Autoclave cure processes were developed for stiffened skin and sandwich structures. The stiffness, strength, notch sensitivity, and bearing/bypass properties of fiber-placed skin materials and braided/RTM'd circumferential frame materials were characterized. The strength and durability of cocured and cobonded joints were evaluated. Impact damage resistance of stiffened skin and sandwich structures typical of fuselage panels was investigated. Fluid penetration and migration mechanisms for sandwich panels were studied.

  17. Advanced Technology Composite Fuselage: Program Overview

    NASA Technical Reports Server (NTRS)

    Ilcewicz, L. B.; Smith, P. J.; Hanson, C. T.; Walker, T. H.; Metschan, S. L.; Mabson, G. E.; Wilden, K. S.; Flynn, B. W.; Scholz, D. B.; Polland, D. R.; Fredrikson, H. G.; Olson, J. T.; Backman, B. F.

    1997-01-01

    The Advanced Technology Composite Aircraft Structures (ATCAS) program has studied transport fuselage structure with a large potential reduction in the total direct operating costs for wide-body commercial transports. The baseline fuselage section was divided into four 'quadrants', crown, keel, and sides, gaining the manufacturing cost advantage possible with larger panels. Key processes found to have savings potential include (1) skins laminated by automatic fiber placement, (2) braided frames using resin transfer molding, and (3) panel bond technology that minimized mechanical fastening. The cost and weight of the baseline fuselage barrel was updated to complete Phase B of the program. An assessment of the former, which included labor, material, and tooling costs, was performed with the help of design cost models. Crown, keel, and side quadrant cost distributions illustrate the importance of panel design configuration, area, and other structural details. Composite sandwich panel designs were found to have the greatest cost savings potential for most quadrants. Key technical findings are summarized as an introduction to the other contractor reports documenting Phase A and B work completed in functional areas. The current program status in resolving critical technical issues is also highlighted.

  18. Advanced composite fuselage technology

    NASA Technical Reports Server (NTRS)

    Ilcewicz, Larry B.; Smith, Peter J.; Horton, Ray E.

    1993-01-01

    Boeing's ATCAS program has completed its third year and continues to progress towards a goal to demonstrate composite fuselage technology with cost and weight advantages over aluminum. Work on this program is performed by an integrated team that includes several groups within The Boeing Company, industrial and university subcontractors, and technical support from NASA. During the course of the program, the ATCAS team has continued to perform a critical review of composite developments by recognizing advances in metal fuselage technology. Despite recent material, structural design, and manufacturing advancements for metals, polymeric matrix composite designs studied in ATCAS still project significant cost and weight advantages for future applications. A critical path to demonstrating technology readiness for composite transport fuselage structures was created to summarize ATCAS tasks for Phases A, B, and C. This includes a global schedule and list of technical issues which will be addressed throughout the course of studies. Work performed in ATCAS since the last ACT conference is also summarized. Most activities relate to crown quadrant manufacturing scaleup and performance verification. The former was highlighted by fabricating a curved, 7 ft. by 10 ft. panel, with cocured hat-stiffeners and cobonded J-frames. In building to this scale, process developments were achieved for tow-placed skins, drape formed stiffeners, braided/RTM frames, and panel cure tooling. Over 700 tests and supporting analyses have been performed for crown material and design evaluation, including structural tests that demonstrated limit load requirements for severed stiffener/skin failsafe damage conditions. Analysis of tests for tow-placed hybrid laminates with large damage indicates a tensile fracture toughness that is higher than that observed for advanced aluminum alloys. Additional recent ATCAS achievements include crown supporting technology, keel quadrant design evaluation, and

  19. Optical examination of load transfer in riveted lap joints using portable holographic interferometry

    NASA Astrophysics Data System (ADS)

    Shankar, Krishnakumar; Baird, John P.; Clark, Robert K.; Williamson, Hugh M.

    1997-03-01

    In mechanically fastened single lap joints, such as those employed on aircraft fuselage skin splices, there are two distinct mechanisms of load transfer. At low values of load the transfer occurs primarily through friction between the component sheets while at higher loads the load is transferred by friction as well as through bearing at the fasteners. The load level at which the bearing mode of load transfer comes into action significantly affects the fatigue life of the joint, since the fasteners are stressed only at loads above this threshold load value. The portable holographic interferometry testing system (PHITS) is a robust, portable and sensitive non-destructive inspection system which produces contours of relative out of plane displacement by the method of superposition. PHITS is applied here to monitor the load transfer mechanism and identify the threshold at which the bearing mode comes into effect. In the friction mode there is no relative displacement between the fasteners and the skin panels. In the bearing mode the fasteners are loaded, causing a distinct tipping of the rivets, which is readily observable in the fringe pattern of deflection contours recorded by the holographic system.

  20. Helicopter fuselage drag - combined computational fluid dynamics and experimental studies

    NASA Astrophysics Data System (ADS)

    Batrakov, A.; Kusyumov, A.; Mikhailov, S.; Pakhov, V.; Sungatullin, A.; Valeev, M.; Zherekhov, V.; Barakos, G.

    2015-06-01

    In this paper, wind tunnel experiments are combined with Computational Fluid Dynamics (CFD) aiming to analyze the aerodynamics of realistic fuselage configurations. A development model of the ANSAT aircraft and an early model of the AKTAI light helicopter were employed. Both models were tested at the subsonic wind tunnel of KNRTU-KAI for a range of Reynolds numbers and pitch and yaw angles. The force balance measurements were complemented by particle image velocimetry (PIV) investigations for the cases where the experimental force measurements showed substantial unsteadiness. The CFD results were found to be in fair agreement with the test data and revealed some flow separation at the rear of the fuselages. Once confidence on the CFD method was established, further modifications were introduced to the ANSAT-like fuselage model to demonstrate drag reduction via small shape changes.

  1. Impact of fuselage incidence on the supersonic aerodynamics of two fighter configurations

    NASA Technical Reports Server (NTRS)

    Wood, R. M.; Miller, D. S.

    1984-01-01

    The results of experimental and theoretical investigations into the effect of fuselage upwash on fighter aircraft wing performance are reported. Wind tunnel trials were performed on 4 percent scale models of two supersonic fighters. The trials were run at Mach 1.6-2.0, an Re of 2,000,000 and at angles of attack (AOA) of -4 to 20 deg. Measurements were made of lift, drag and pitching moments. Two linearized theory supersonic aerodynamic prediction codes, PAN AIR and the SDAS lift analysis, were used to predict the same aerodynamic coefficients. The fuselage AOA augmented the lift and pitching moment at 0, 2 and 5 deg. The contribution mainly arose from the fuselage-induced upwash. The PAN AIR code gave superior data for the fuselage aerodynamics and effects, although both codes accurately predicted the overall lift and moment increments due to the fuselage AOA.

  2. Full-scale testing and analysis of fuselage structure

    NASA Technical Reports Server (NTRS)

    Miller, M.; Gruber, M. L.; Wilkins, K. E.; Worden, R. E.

    1994-01-01

    This paper presents recent results from a program in the Boeing Commercial Airplane Group to study the behavior of cracks in fuselage structures. The goal of this program is to improve methods for analyzing crack growth and residual strength in pressurized fuselages, thus improving new airplane designs and optimizing the required structural inspections for current models. The program consists of full-scale experimental testing of pressurized fuselage panels in both wide-body and narrow-body fixtures and finite element analyses to predict the results. The finite element analyses are geometrically nonlinear with material and fastener nonlinearity included on a case-by-case basis. The analysis results are compared with the strain gage, crack growth, and residual strength data from the experimental program. Most of the studies reported in this paper concern the behavior of single or multiple cracks in the lap joints of narrow-body airplanes (such as 727 and 737 commercial jets). The phenomenon where the crack trajectory is curved creating a 'flap' and resulting in a controlled decompression is discussed.

  3. Full-scale testing and analysis of fuselage structure

    NASA Astrophysics Data System (ADS)

    Miller, M.; Gruber, M. L.; Wilkins, K. E.; Worden, R. E.

    1994-09-01

    This paper presents recent results from a program in the Boeing Commercial Airplane Group to study the behavior of cracks in fuselage structures. The goal of this program is to improve methods for analyzing crack growth and residual strength in pressurized fuselages, thus improving new airplane designs and optimizing the required structural inspections for current models. The program consists of full-scale experimental testing of pressurized fuselage panels in both wide-body and narrow-body fixtures and finite element analyses to predict the results. The finite element analyses are geometrically nonlinear with material and fastener nonlinearity included on a case-by-case basis. The analysis results are compared with the strain gage, crack growth, and residual strength data from the experimental program. Most of the studies reported in this paper concern the behavior of single or multiple cracks in the lap joints of narrow-body airplanes (such as 727 and 737 commercial jets). The phenomenon where the crack trajectory is curved creating a 'flap' and resulting in a controlled decompression is discussed.

  4. Vertical Drop Test of a YS-11 Fuselage Section (Part 2)

    NASA Astrophysics Data System (ADS)

    Iwasaki, Kazuo; Kumakura, Ikuo; Minegishi, Masakutsu; Shoji, Hirokazu; Yoshimoto, Norio; Miyaki, Hiromitsu; Terada, Hiroyuki; Isoe, Akira; Yamaoka, Toshihiro; Katayama, Noriaki; Hayashi, Toru; Akaso, Tetsuya; Kosaka, Hideyuki

    The Structures and Materials Research Center of the National Aerospace Laboratory of Japan (NAL) and Kawasaki Heavy Industries, Ltd. (KHI) conducted the 2nd vertical drop test of a fuselage section cut from a NAMC YS-11 transport airplane in July 2002. The main objective of this test program was to obtain background data for aircraft cabin safety by drop test of a full-scale fuselage section and to develop computational tool for crash simulation of aircraft fuselage structure. The test article including seats and anthropomorphic test dummies was dropped to a rigid impact surface by free-fall method at a velocity of 7.6m/s (25ft/s). The impact environment and the resultant response of the fuselage structure and the passenger dummies were considered to be severe but potentially survivable. A description of the results of the 1st drop test and the 2nd drop test is presented in this paper.

  5. Global cost and weight evaluation of fuselage keel design concepts

    NASA Technical Reports Server (NTRS)

    Flynn, B. W.; Morris, M. R.; Metschan, S. L.; Swanson, G. D.; Smith, P. J.; Griess, K. H.; Schramm, M. R.; Humphrey, R. J.

    1993-01-01

    The Boeing program entitled Advanced Technology Composite Aircraft Structure (ATCAS) is focused on the application of affordable composite technology to pressurized fuselage structure of future aircraft. As part of this effort, a design study was conducted on the keel section of the aft fuselage. A design build team (DBT) approach was used to identify and evaluate several design concepts which incorporated different material systems, fabrication processes, structural configurations, and subassembly details. The design concepts were developed in sufficient detail to accurately assess their potential for cost and weight savings as compared with a metal baseline representing current wide body technology. The cost and weight results, along with an appraisal of performance and producibility risks, are used to identify a globally optimized keel design; one which offers the most promising cost and weight advantages over metal construction. Lastly, an assessment is given of the potential for further cost and weight reductions of the selected keel design during local optimization.

  6. A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints

    NASA Technical Reports Server (NTRS)

    Harris, C. E.; Piascik, R. S.; Newman, J. C., Jr.

    2000-01-01

    An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.

  7. A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Piascik, Robert S.; Newman, James C., Jr.

    1999-01-01

    An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.

  8. 14 CFR 25.783 - Fuselage doors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuselage doors. 25.783 Section 25.783... Fuselage doors. (a) General. This section applies to fuselage doors, which includes all doors, hatches... of tools to open or close. This also applies to each door or hatch through a pressure...

  9. 14 CFR 25.783 - Fuselage doors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuselage doors. 25.783 Section 25.783... Fuselage doors. (a) General. This section applies to fuselage doors, which includes all doors, hatches... of tools to open or close. This also applies to each door or hatch through a pressure...

  10. Effect of fuselage upwash on the supersonic longitudinal aerodynamic characteristics of 2 fighter configurations

    NASA Technical Reports Server (NTRS)

    Wood, R. M.; Miller, D. S.

    1984-01-01

    An experimental and theoretical investigation of fuselage incidence effects on two fighter aircraft models, which differed in wing planform only, has been conducted in the Langley Unitary Plan Wind Tunnel at Mach numbers of 1.6, 1.8, and 2.0. Results were obtained on the two models at fuselage incidence angles of 0 deg, 2 deg, and 5 deg. The fuselage geometry included two side-mounted, flow-through, half-axisymmetric inlets and twin vertical tails. The two planforms tested were cranked wings with 70 deg/66 deg and 70 deg/30 deg leading-edge sweep angles. Experimental data showed that fuselage incidence resulted in positive increments in configuration lift and pitching moment; most of the lift increment can be attributed to the fuselage-induced upwash acting on the wing and most of the pitching-moment increment is due to the fuselage. Theoretical analysis indicates that linear-theory methods can adequately predict the overall configuration forces and moments resulting from fuselage upwash, but a higher order surface-panel method (PAN AIR) more accurately predicted the distribution of forces and resulting moments between the components.

  11. Continued development and correlation of analytically based weight estimation codes for wings and fuselages

    NASA Technical Reports Server (NTRS)

    Mullen, J., Jr.

    1978-01-01

    The implementation of the changes to the program for Wing Aeroelastic Design and the development of a program to estimate aircraft fuselage weights are described. The equations to implement the modified planform description, the stiffened panel skin representation, the trim loads calculation, and the flutter constraint approximation are presented. A comparison of the wing model with the actual F-5A weight material distributions and loads is given. The equations and program techniques used for the estimation of aircraft fuselage weights are described. These equations were incorporated as a computer code. The weight predictions of this program are compared with data from the C-141.

  12. Impact damage resistance of composite fuselage structure, part 1

    NASA Technical Reports Server (NTRS)

    Dost, E. F.; Avery, W. B.; Ilcewicz, L. B.; Grande, D. H.; Coxon, B. R.

    1992-01-01

    The impact damage resistance of laminated composite transport aircraft fuselage structures was studied experimentally. A statistically based designed experiment was used to examine numerous material, laminate, structural, and extrinsic (e.g., impactor type) variables. The relative importance and quantitative measure of the effect of each variable and variable interactions on responses including impactor dynamic response, visibility, and internal damage state were determined. The study utilized 32 three-stiffener panels, each with a unique combination of material type, material forms, and structural geometry. Two manufacturing techniques, tow placement and tape lamination, were used to build panels representative of potential fuselage crown, keel, and lower side-panel designs. Various combinations of impactor variables representing various foreign-object-impact threats to the aircraft were examined. Impacts performed at different structural locations within each panel (e.g., skin midbay, stiffener attaching flange, etc.) were considered separate parallel experiments. The relationship between input variables, measured damage states, and structural response to this damage are presented including recommendations for materials and impact test methods for fuselage structure.

  13. Crash Simulation of a Boeing 737 Fuselage Section Vertical Drop Test

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Jackson, Karen E.; Jones, Yvonne T.; Frings, Gary; Vu, Tong

    2004-01-01

    A 30-ft/s vertical drop test of a fuselage section of a Boeing 737 aircraft was conducted in October of 1999 at the FAA Technical Center in Atlantic City, NJ. This test was performed to evaluate the structural integrity of a conformable auxiliary fuel tank mounted beneath the floor and to determine its effect on the impact response of the airframe structure and the occupants. The test data were used to compare with a finite element simulation of the fuselage structure and to gain a better understanding of the impact physics through analytical/experimental correlation. To perform this simulation, a full-scale 3-dimensional finite element model of the fuselage section was developed using the explicit, nonlinear transient-dynamic finite element code, MSC.Dytran. The emphasis of the simulation was to predict the structural deformation and floor-level acceleration responses obtained from the drop test of the B737 fuselage section with the auxiliary fuel tank.

  14. Application of a design-build-team approach to low cost and weight composite fuselage structure

    NASA Technical Reports Server (NTRS)

    Ilcewicz, L. B.; Walker, T. H.; Willden, K. S.; Swanson, G. D.; Truslove, G.; Metschan, S. L.; Pfahl, C. L.

    1991-01-01

    Relationships between manufacturing costs and design details must be understood to promote the application of advanced composite technologies to transport fuselage structures. A team approach, integrating the disciplines responsible for aircraft structural design and manufacturing, was developed to perform cost and weight trade studies for a twenty-foot diameter aft fuselage section. Baseline composite design and manufacturing concepts were selected for large quadrant panels in crown, side, and keel areas of the fuselage section. The associated technical issues were also identified. Detailed evaluation of crown panels indicated the potential for large weight savings and costs competitive with aluminum technology in the 1995 timeframe. Different processes and material forms were selected for the various elements that comprise the fuselage structure. Additional cost and weight savings potential was estimated for future advancements.

  15. Cabin-fuselage-wing structural design concept with engine installation

    NASA Technical Reports Server (NTRS)

    Ariotti, Scott; Garner, M.; Cepeda, A.; Vieira, J.; Bolton, D.

    1993-01-01

    The purpose of this project is to provide a fuselage structural assembly and wing structural design that will be able to withstand the given operational parameters and loads provided by Federal Aviation Regulation Part 23 (FAR 23) and the Statement of Work (SOW). The goal is to provide a durable lightweight structure that will transfer the applied loads through the most efficient load path. Areas of producibility and maintainability of the structure will also be addressed. All of the structural members will also meet or exceed the desired loading criteria, along with providing adequate stiffness, reliability, and fatigue life as stated in the SOW. Considerations need to be made for control system routing and cabin heating/ventilation. The goal of the wing structure and carry through structure is also to provide a simple, lightweight structure that will transfer the aerodynamic forces produced by the wing, tailboom, and landing gear. These forces will be channeled through various internal structures sized for the pre-determined loading criteria. Other considerations were to include space for flaps, ailerons, fuel tanks, and electrical and control system routing. The difficulties encountered in the fuselage design include expanding the fuselage cabin to accept a third occupant in a staggered configuration and providing ample volume for their safety. By adding a third person the CG of aircraft will move forward so the engine needs to be moved aft to compensate for the difference in the moment. This required the provisions of a ring frame structure for the new position of the engine mount. The difficulties encountered in the wing structural design include resizing the wing for the increased capacity and weight, and compensating for a large torsion produced by the tail boom by placing a great number of stiffeners inside the boom, which will result in the relocation of the fuel tank. Finally, an adequate carry through structure for the wing and fuselage interface will be

  16. Crack Growth Simulation and Residual Strength Prediction in Airplane Fuselages

    NASA Technical Reports Server (NTRS)

    Chen, Chuin-Shan; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1999-01-01

    This is the final report for the NASA funded project entitled "Crack Growth Prediction Methodology for Multi-Site Damage." The primary objective of the project was to create a capability to simulate curvilinear fatigue crack growth and ductile tearing in aircraft fuselages subjected to widespread fatigue damage. The second objective was to validate the capability by way of comparisons to experimental results. Both objectives have been achieved and the results are detailed herein. In the first part of the report, the crack tip opening angle (CTOA) fracture criterion, obtained and correlated from coupon tests to predict fracture behavior and residual strength of built-up aircraft fuselages, is discussed. Geometrically nonlinear, elastic-plastic, thin shell finite element analyses are used to simulate stable crack growth and to predict residual strength. Both measured and predicted results of laboratory flat panel tests and full-scale fuselage panel tests show substantial reduction of residual strength due to the occurrence of multi-site damage (MSD). Detailed comparisons of n stable crack growth history, and residual strength between the predicted and experimental results are used to assess the validity of the analysis methodology. In the second part of the report, issues related to crack trajectory prediction in thin shells; an evolving methodology uses the crack turning phenomenon to improve the structural integrity of aircraft structures are discussed, A directional criterion is developed based on the maximum tangential stress theory, but taking into account the effect of T-stress and fracture toughness orthotropy. Possible extensions of the current crack growth directional criterion to handle geometrically and materially nonlinear problems are discussed. The path independent contour integral method for T-stress evaluation is derived and its accuracy is assessed using a p- and hp-version adaptive finite element method. Curvilinear crack growth is simulated in

  17. Algebraic grid generation about wing-fuselage bodies

    NASA Technical Reports Server (NTRS)

    Smith, R.E.; Kudlinski, R. A.; Everton, E. L.; Wiese, M. R.

    1987-01-01

    An algebraic procedure for generating boundary-fitted grids about wing-fuselage configurations is presented. A wing-fuselage configuration consists of two aircraft components specified by cross sections and mathematically represented by Coons' patches. Several grid blocks are constructed to cover the entire region surrounding the configuration, and each grid block maps into a computational cube. Grid points are first determined on the six boundary surfaces of a block and then in the interior. Grid points on the surface of the configuration are derived from the intersection of planes with the Coons' patch definition. Approximate arc length distributions along the resulting grid curves concentrate and disperse grid points. The two-boundary technique and transfinite interpolation are used to determine grid points on the remaining boundary surfaces and block interiors.

  18. Design and Analysis of a Stiffened Composite Fuselage Panel

    NASA Technical Reports Server (NTRS)

    Dickson, J. N.; Biggers, S. B.

    1980-01-01

    A stiffened composite panel has been designed that is representative of the fuselage structure of existing wide bodied aircraft. The panel is a minimum weight design, based on the current level of technology and realistic loads and criteria. Several different stiffener configurations were investigated in the optimization process. The final configuration is an all graphite epoxy J-stiffened design in which the skin between adjacent stiffeners is permitted to buckle under design loads. Fail-safe concepts typically employed in metallic fuselage structure have been incorporated in the design. A conservative approach has been used with regard to structural details such as skin frame and stringer frame attachments and other areas where sufficient design data was not available.

  19. Design and analysis of a stiffened composite fuselage panel

    NASA Technical Reports Server (NTRS)

    Dickson, J. N.; Biggers, S. B.

    1980-01-01

    The design and analysis of stiffened composite panel that is representative of the fuselage structure of existing wide bodied aircraft is discussed. The panel is a minimum weight design, based on the current level of technology and realistic loads and criteria. Several different stiffener configurations were investigated in the optimization process. The final configuration is an all graphite/epoxy J-stiffened design in which the skin between adjacent stiffeners is permitted to buckle under design loads. Fail safe concepts typically employed in metallic fuselage structure have been incorporated in the design. A conservative approach has been used with regard to structural details such as skin/frame and stringer/frame attachments and other areas where sufficient design data was not available.

  20. Transonic Flow Field Analysis for Wing-Fuselage Configurations

    NASA Technical Reports Server (NTRS)

    Boppe, C. W.

    1980-01-01

    A computational method for simulating the aerodynamics of wing-fuselage configurations at transonic speeds is developed. The finite difference scheme is characterized by a multiple embedded mesh system coupled with a modified or extended small disturbance flow equation. This approach permits a high degree of computational resolution in addition to coordinate system flexibility for treating complex realistic aircraft shapes. To augment the analysis method and permit applications to a wide range of practical engineering design problems, an arbitrary fuselage geometry modeling system is incorporated as well as methodology for computing wing viscous effects. Configuration drag is broken down into its friction, wave, and lift induced components. Typical computed results for isolated bodies, isolated wings, and wing-body combinations are presented. The results are correlated with experimental data. A computer code which employs this methodology is described.

  1. Design of fuselage shapes for natural laminar flow

    NASA Technical Reports Server (NTRS)

    Dodbele, S. S.; Vandam, C. P.; Vijgen, P. M. H. W.

    1986-01-01

    Recent technological advances in airplane construction techniques and materials allow for the production of aerodynamic surfaces without significant waviness and roughness, permitting long runs of natural laminar flow (NLF). The present research effort seeks to refine and validate computational design tools for use in the design of axisymmetric and nonaxisymmetric natural-laminar-flow bodies. The principal task of the investigation involves fuselage body shaping using a computational design procedure. Analytical methods were refined and exploratory calculations conducted to predict laminar boundary-layer on selected body shapes. Using a low-order surface-singularity aerodynamic analysis program, pressure distribution, boundary-layer development, transition location and drag coefficient have been obtained for a number of body shapes including a representative business-aircraft fuselage. Extensive runs of laminar flow were predicted in regions of favorable pressure gradient on smooth body surfaces. A computational design procedure was developed to obtain a body shape with minimum drag having large extent of NLF.

  2. Design of fuselage shapes for natural laminar flow

    NASA Astrophysics Data System (ADS)

    Dodbele, S. S.; Vandam, C. P.; Vijgen, P. M. H. W.

    1986-03-01

    Recent technological advances in airplane construction techniques and materials allow for the production of aerodynamic surfaces without significant waviness and roughness, permitting long runs of natural laminar flow (NLF). The present research effort seeks to refine and validate computational design tools for use in the design of axisymmetric and nonaxisymmetric natural-laminar-flow bodies. The principal task of the investigation involves fuselage body shaping using a computational design procedure. Analytical methods were refined and exploratory calculations conducted to predict laminar boundary-layer on selected body shapes. Using a low-order surface-singularity aerodynamic analysis program, pressure distribution, boundary-layer development, transition location and drag coefficient have been obtained for a number of body shapes including a representative business-aircraft fuselage. Extensive runs of laminar flow were predicted in regions of favorable pressure gradient on smooth body surfaces. A computational design procedure was developed to obtain a body shape with minimum drag having large extent of NLF.

  3. Light aircraft sound transmission study

    NASA Technical Reports Server (NTRS)

    Atwal, M.; David, J.; Heitman, K.; Crocker, M. J.

    1983-01-01

    The revived interest in the design of propeller driven aircraft is based on increasing fuel prices as well as on the need for bigger short haul and commuter aircraft. A major problem encountered with propeller driven aircraft is propeller and exhaust noise that is transmitted through the fuselage sidewall structure. Part of the work which was conducted during the period April 1 to August 31, 1983, on the studies of sound transmission through light aircraft walls is presented.

  4. Crashworthy Evaluation of a 1/5-Scale Model Composite Fuselage Concept

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Fasanella, Edwin L.

    1999-01-01

    A 1/5-scale model composite fuselage concept for light aircraft and rotorcraft has been developed to satisfy structural and flight loads requirements and to satisfy design goals for improved crashworthiness. The 1/5-scale model fuselage consists of a relatively rigid upper section which forms the passenger cabin, a stiff structural floor, and an energy absorbing subfloor which is designed to limit impact forces during a crash event. The focus of the present paper is to describe the crashworthy evaluation of the fuselage concept through impact testing and finite element simulation using the nonlinear, explicit transient dynamic code, MSC/DYTRAN. The energy absorption behavior of two different subfloor configurations was determined through quasi-static crushing tests. For the dynamic evaluation, each subfloor configuration was incorporated into a 1/5-scale model fuselage section, which was impacted at 31 ft/s vertical velocity onto a rigid surface. The experimental data demonstrate that the fuselage section with a foam-filled subfloor configuration satisfied the impact design requirement. In addition, the fuselage section maintained excellent energy absorption behavior for a 31 ft/s vertical drop test with a 15 deg-roll impact attitude. Good correlation was obtained between the experimental data and analytical results for both impact conditions.

  5. Coupled rotor and fuselage equations of motion

    NASA Technical Reports Server (NTRS)

    Warmbrodt, W.

    1979-01-01

    The governing equations of motion of a helicopter rotor coupled to a rigid body fuselage are derived. A consistent formulation is used to derive nonlinear periodic coefficient equations of motion which are used to study coupled rotor/fuselage dynamics in forward flight. Rotor/fuselage coupling is documented and the importance of an ordering scheme in deriving nonlinear equations of motion is reviewed. The nature of the final equations and the use of multiblade coordinates are discussed.

  6. Nonlinear analysis of damaged stiffened fuselage shells subjected to combined loads

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Britt, Vicki O.; Young, Richard D.; Rankin, Charles C.; Shore, Charles P.; Bains, Jane C.

    1994-01-01

    The results of an analytical study of the nonlinear response of stiffened fuselage shells with long cracks are presented. The shells are modeled with a hierarchical modeling strategy that accounts for global and local response phenomena accurately. Results are presented for internal pressure and mechanical bending loads. The effects of crack location and orientation on shell response are described. The effects of mechanical fasteners on the response of a lap joint and the effects of elastic and elastic-plastic material properties on the buckling response of tension-loaded flat panels with cracks are also addressed.

  7. Composite Lightning Rods for Aircraft

    NASA Technical Reports Server (NTRS)

    Bryan, Charles F., Jr.

    1986-01-01

    Composite, lightweight sacrificial tip with graphite designed reduces lightning-strike damage to composite parts of aircraft and dissipates harmful electrical energy. Device consists of slender composite rod fabricated from highly-conductive unidirectional reinforcing fibers in matrix material. Rods strategically installed in trailing edges of aircraft wings, tails, winglets, control surfaces, and rearward-most portion of aft fuselage.

  8. Aircraft Configured for Flight in an Atmosphere Having Low Density

    NASA Technical Reports Server (NTRS)

    Croom, Mark A. (Inventor); Smith, Stephen C. (Inventor); Gelhausen, Paul A. (Inventor); Guynn, Mark D. (Inventor); Hunter, Craig A. (Inventor); Paddock, David A. (Inventor); Riddick, Steven E. (Inventor); Teter, Jr., John E. (Inventor)

    2012-01-01

    An aircraft is configured for flight in an atmosphere having a low density. The aircraft includes a fuselage, a pair of wings, and a rear stabilizer. The pair of wings extends from the fuselage in opposition to one another. The rear stabilizer extends from the fuselage in spaced relationship to the pair of wings. The fuselage, the wings, and the rear stabilizer each present an upper surface opposing a lower surface. The upper and lower surfaces have X, Y, and Z coordinates that are configured for flight in an atmosphere having low density.

  9. Advanced Technology Composite Fuselage - Repair and Damage Assessment Supporting Maintenance

    NASA Technical Reports Server (NTRS)

    Flynn, B. W.; Bodine, J. B.; Dopker, B.; Finn, S. R.; Griess, K. H.; Hanson, C. T.; Harris, C. G.; Nelson, K. M.; Walker, T. H.; Kennedy, T. C.; Nahan, M. F.

    1997-01-01

    Under the NASA-sponsored contracts for Advanced Technology Composite Aircraft Structures (ATCAS) and Materials Development Omnibus Contract (MDOC), Boeing is studying the technologies associated with the application of composite materials to commercial transport fuselage structure. Included in the study is the incorporation of maintainability and repairability requirements of composite primary structure into the design. This contractor report describes activities performed to address maintenance issues in composite fuselage applications. A key aspect of the study was the development of a maintenance philosophy which included consideration of maintenance issues early in the design cycle, multiple repair options, and airline participation in design trades. Fuselage design evaluations considered trade-offs between structural weight, damage resistance/tolerance (repair frequency), and inspection burdens. Analysis methods were developed to assess structural residual strength in the presence of damage, and to evaluate repair design concepts. Repair designs were created with a focus on mechanically fastened concepts for skin/stringer structure and bonded concepts for sandwich structure. Both a large crown (skintstringer) and keel (sandwich) panel were repaired. A compression test of the keel panel indicated the demonstrated repairs recovered ultimate load capability. In conjunction with the design and manufacturing developments, inspection methods were investigated for their potential to evaluate damaged structure and verify the integrity of completed repairs.

  10. Cabin fuselage structural design with engine installation and control system

    NASA Technical Reports Server (NTRS)

    Balakrishnan, Tanapaal; Bishop, Mike; Gumus, Ilker; Gussy, Joel; Triggs, Mike

    1994-01-01

    Design requirements for the cabin, cabin system, flight controls, engine installation, and wing-fuselage interface that provide adequate interior volume for occupant seating, cabin ingress and egress, and safety are presented. The fuselage structure must be sufficient to meet the loadings specified in the appropriate sections of Federal Aviation Regulation Part 23. The critical structure must provide a safe life of 10(exp 6) load cycles and 10,000 operational mission cycles. The cabin seating and controls must provide adjustment to account for various pilot physiques and to aid in maintenance and operation of the aircraft. Seats and doors shall not bind or lockup under normal operation. Cabin systems such as heating and ventilation, electrical, lighting, intercom, and avionics must be included in the design. The control system will consist of ailerons, elevator, and rudders. The system must provide required deflections with a combination of push rods, bell cranks, pulleys, and linkages. The system will be free from slack and provide smooth operation without binding. Environmental considerations include variations in temperature and atmospheric pressure, protection against sand, dust, rain, humidity, ice, snow, salt/fog atmosphere, wind and gusts, and shock and vibration. The following design goals were set to meet the requirements of the statement of work: safety, performance, manufacturing and cost. To prevent the engine from penetrating the passenger area in the event of a crash was the primary safety concern. Weight and the fuselage aerodynamics were the primary performance concerns. Commonality and ease of manufacturing were major considerations to reduce cost.

  11. Advanced Technology Composite Fuselage-Structural Performance

    NASA Technical Reports Server (NTRS)

    Walker, T. H.; Minguet, P. J.; Flynn, B. W.; Carbery, D. J.; Swanson, G. D.; Ilcewicz, L. B.

    1997-01-01

    Boeing is studying the technologies associated with the application of composite materials to commercial transport fuselage structure under the NASA-sponsored contracts for Advanced Technology Composite Aircraft Structures (ATCAS) and Materials Development Omnibus Contract (MDOC). This report addresses the program activities related to structural performance of the selected concepts, including both the design development and subsequent detailed evaluation. Design criteria were developed to ensure compliance with regulatory requirements and typical company objectives. Accurate analysis methods were selected and/or developed where practical, and conservative approaches were used where significant approximations were necessary. Design sizing activities supported subsequent development by providing representative design configurations for structural evaluation and by identifying the critical performance issues. Significant program efforts were directed towards assessing structural performance predictive capability. The structural database collected to perform this assessment was intimately linked to the manufacturing scale-up activities to ensure inclusion of manufacturing-induced performance traits. Mechanical tests were conducted to support the development and critical evaluation of analysis methods addressing internal loads, stability, ultimate strength, attachment and splice strength, and damage tolerance. Unresolved aspects of these performance issues were identified as part of the assessments, providing direction for future development.

  12. Test and analysis results for composite transport fuselage and wing structures

    NASA Technical Reports Server (NTRS)

    Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

    1992-01-01

    Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being studied as cost effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. Data are presented to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade stiffened compression tests and stiffener pull-off tests.

  13. Alleviation of fuselage form drag using vortex flows: Final report

    SciTech Connect

    Wortman, A.

    1987-09-15

    The concept of using vortex generators to reduce the fuselage form drag of transport aircraft combines the outflow from the plane of symmetry which is induced by the rotational component of the vortex flow with the energization of the boundary layer to reduce the momentum thickness and to delay or eliminate flow separation. This idea was first advanced by the author in 1981. Under a DOE grant, the concept was validated in wind tunnel tests of approximately 1:17 scale models of fuselages of Boeing 747 and Lockheed C-5 aircraft. The search for the minimum drag involved three vortex generator configurations with three sizes of each in six locations clustered in the aft regions of the fuselages at the beginning of the tail upsweep. The local Reynolds number, which is referred to the length of boundary layer run from the nose, was approximately 10{sup 7} so that a fully developed turbulent boundary layer was present. Vortex generator planforms ranged from swept tapered, through swept straight, to swept reverse tapered wings whose semi-spans ranged from 50% to 125% of the local boundary layer thickness. Pitch angles of the vortex generators were varied by inboard actuators under the control of an external proportional digital radio controller. It was found that certain combinations of vortex generator parameters increased drag. However, with certain configurations, locations, and pitch angles of vortex generators, the highest drag reductions were 3% for the 747 and about 6% for the C-5, thus confirming the arguments that effectiveness increases with the rate of upsweep of the tail. Greatest gains in performance are therefore expected on aft loading military transports. 10 refs., 11 figs., 1 tab.

  14. Test and analysis results for composite transport fuselage and wing structures

    NASA Technical Reports Server (NTRS)

    Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

    1992-01-01

    Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being investigated by researchers at NASA LaRC and Douglas Aircraft Company as cost-effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. The Douglas work is being performed under a NASA contract entitled 'Innovative Composites Aircraft Primary Structures (ICAPS)'. Data are presented in this paper to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three-J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade-stiffened compression tests and stiffener pull-off tests.

  15. Cashier/Checker Learning Activity Packets (LAPs).

    ERIC Educational Resources Information Center

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Twenty-four learning activity packets (LAPs) are provided for six areas of instruction in a cashier/checker program. Section A, Orientation, contains an LAP on exploring the job of cashier-checker. Section B, Operations, has nine LAPs, including those on operating the cash register, issuing trading stamps, and completing the cash register balance…

  16. Fuselage panel noise attenuation by piezoelectric switching control

    NASA Astrophysics Data System (ADS)

    Makihara, Kanjuro; Miyakawa, Takeya; Onoda, Junjiro; Minesugi, Kenji

    2010-08-01

    This paper describes a problem that we encountered in our noise attenuation project and our solution for it. We intend to attenuate low-frequency noise that transmits through aircraft fuselage panels. Our method of noise attenuation is implemented with a piezoelectric semi-active system having a selective switch instead of an active energy-supply system. The semi-active controller is based on the predicted sound pressure distribution obtained from acoustic emission analysis. Experiments and numerical simulations demonstrate that the semi-active method attenuates acoustic levels of not only the simple monochromatic noise but also of broadband noise. We reveal that tuning the electrical parameters in the circuit is the key to effective noise attenuation, to overcome the acoustic excitation problem due to sharp switching actions, as well as to control chattering problems. The results obtained from this investigation provide meaningful insights into designing noise attenuation systems for comfortable aircraft cabin environments.

  17. Additive manufacturing of tools for lapping glass

    NASA Astrophysics Data System (ADS)

    Williams, Wesley B.

    2013-09-01

    Additive manufacturing technologies have the ability to directly produce parts with complex geometries without the need for secondary processes, tooling or fixtures. This ability was used to produce concave lapping tools with a VFlash 3D printer from 3D Systems. The lapping tools were first designed in Creo Parametric with a defined constant radius and radial groove pattern. The models were converted to stereolithography files which the VFlash used in building the parts, layer by layer, from a UV curable resin. The tools were rotated at 60 rpm and used with 120 grit and 220 grit silicon carbide lapping paste to lap 0.750" diameter fused silica workpieces. The samples developed a matte appearance on the lapped surface that started as a ring at the edge of the workpiece and expanded to the center. This indicated that as material was removed, the workpiece radius was beginning to match the tool radius. The workpieces were then cleaned and lapped on a second tool (with equivalent geometry) using a 3000 grit corundum aluminum oxide lapping paste, until a near specular surface was achieved. By using lapping tools that have been additively manufactured, fused silica workpieces can be lapped to approach a specified convex geometry. This approach may enable more rapid lapping of near net shape workpieces that minimize the material removal required by subsequent polishing. This research may also enable development of new lapping tool geometry and groove patterns for improved loose abrasive finishing.

  18. Astronaut Eileen Collins in Full Fuselage Trainer

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Astronaut Eileen M. Collins, pilot for the STS-63 mission, participates in STS-63 training at JSC's Shuttle mockup and integration laboratory. Collins is seated at the pilot's station in the Full Fuselage Trainer (FFT).

  19. How Tongue Size and Roughness Affect Lapping

    NASA Astrophysics Data System (ADS)

    Hubbard, M. J.; Hay, K. M.

    2012-10-01

    The biomechanics of domestic cat lapping (Felis catus) and domestic dog lapping (Canis familiaris) is currently under debate. Lapping mechanics in vertebrates with incomplete cheeks, such as cats and dogs, is a balance of inertia and the force of gravity likely optimized for ingestion and physical necessities. Physiology dictates vertebrate mass, which dictates vertebrate tongue size, which dictates lapping mechanics to achieve optimum liquid ingestion; with either touch lapping, scooping, or a hybrid lapping method. The physics of this optimized system then determines how high a column of liquid can be raised before it collapses due to gravity, and therefore, lapping frequency. Through tongue roughness model variation experiments it was found that pore-scale geometrical roughness does not appear to affect lapping or liquid uptake. Through tongue size model variation experiments it was found that there is a critical tongue radius in the range of 25 mm to 35 mm above which touch lapping is no longer an efficient way to uptake liquid. Vertebrates with incomplete cheeks may use a touch lapping method to ingest water if their tongue radius is less than this critical radius and use an alternative ingestion method if their tongue radius is larger.

  20. Residual Strength Prediction of Fuselage Structures with Multiple Site Damage

    NASA Technical Reports Server (NTRS)

    Chen, Chuin-Shan; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1999-01-01

    This paper summarizes recent results on simulating full-scale pressure tests of wide body, lap-jointed fuselage panels with multiple site damage (MSD). The crack tip opening angle (CTOA) fracture criterion and the FRANC3D/STAGS software program were used to analyze stable crack growth under conditions of general yielding. The link-up of multiple cracks and residual strength of damaged structures were predicted. Elastic-plastic finite element analysis based on the von Mises yield criterion and incremental flow theory with small strain assumption was used. A global-local modeling procedure was employed in the numerical analyses. Stress distributions from the numerical simulations are compared with strain gage measurements. Analysis results show that accurate representation of the load transfer through the rivets is crucial for the model to predict the stress distribution accurately. Predicted crack growth and residual strength are compared with test data. Observed and predicted results both indicate that the occurrence of small MSD cracks substantially reduces the residual strength. Modeling fatigue closure is essential to capture the fracture behavior during the early stable crack growth. Breakage of a tear strap can have a major influence on residual strength prediction.

  1. The effects of design details on cost and weight of fuselage structures

    NASA Technical Reports Server (NTRS)

    Swanson, G. D.; Metschan, S. L.; Morris, M. R.; Kassapoglou, C.

    1993-01-01

    Crown panel design studies showing the relationship between panel size, cost, weight, and aircraft configuration are compared to aluminum design configurations. The effects of a stiffened sandwich design concept are also discussed. This paper summarizes the effect of a design cost model in assessing the cost and weight relationships for fuselage crown panel designs. Studies were performed using data from existing aircraft to assess the effects of different design variables on the cost and weight of transport fuselage crown panel design. Results show a strong influence of load levels, panel size, and material choices on the cost and weight of specific designs. A design tool being developed under the NASA ACT program is used in the study to assess these issues. The effects of panel configuration comparing postbuckled and buckle resistant stiffened laminated structure is compared to a stiffened sandwich concept. Results suggest some potential economy with stiffened sandwich designs for compression dominated structure with relatively high load levels.

  2. Mechanical and analytical screening of braided composites for transport fuselage applications

    NASA Technical Reports Server (NTRS)

    Fedro, Mark J.; Gunther, Christian; Ko, Frank K.

    1991-01-01

    The mechanics of materials progress in support of the goal of understanding the application of braided composites in a transport aircraft fuselage are summarized. Composites consisting of both 2-D and 3-D braid patterns are investigated. Both consolidation of commingled graphite/PEEK and resin transfer molding of graphite-epoxy braided composite processes are studied. Mechanical tests were used to examine unnotched tension, open hole tension, compression, compression after impact, in-plane shear, out-of-plane tension, bearing, and crippling. Analytical methods are also developed and applied to predict the stiffness and strengths of test specimens. A preliminary study using the test data and analytical results is performed to assess the applicability of braided composites to a commercial aircraft fuselage.

  3. Residual Strength Pressure Tests and Nonlinear Analyses of Stringer-and Frame-Stiffened Aluminum Fuselage Panels with Longitudinal Cracks

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Rouse, Marshall; Ambur, Damodar R.; Starnes, James H., Jr.

    1998-01-01

    The results of residual strength pressure tests and nonlinear analyses of stringer- and frame-stiffened aluminum fuselage panels with longitudinal cracks are presented. Two types of damage are considered: a longitudinal crack located midway between stringers, and a longitudinal crack adjacent to a stringer and along a row of fasteners in a lap joint that has multiple-site damage (MSD). In both cases, the longitudinal crack is centered on a severed frame. The panels are subjected to internal pressure plus axial tension loads. The axial tension loads are equivalent to a bulkhead pressure load. Nonlinear elastic-plastic residual strength analyses of the fuselage panels are conducted using a finite element program and the crack-tip-opening-angle (CTOA) fracture criterion. Predicted crack growth and residual strength results from nonlinear analyses of the stiffened fuselage panels are compared with experimental measurements and observations. Both the test and analysis results indicate that the presence of MSD affects crack growth stability and reduces the residual strength of stiffened fuselage shells with long cracks.

  4. Residual Strength Pressure Tests and Nonlinear Analyses of Stringer- and Frame-Stiffened Aluminum Fuselage Panels with Longitudinal Cracks

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Rouse, Marshall; Ambur, Damodar R.; Starnes, James H., Jr.

    1999-01-01

    The results of residual strength pressure tests and nonlinear analyses of stringer- and frame-stiffened aluminum fuselage panels with longitudinal cracks are presented. Two types of damage are considered: a longitudinal crack located midway between stringers, and a longitudinal crack adjacent to a stringer and along a row of fasteners in a lap joint that has multiple-site damage (MSD). In both cases, the longitudinal crack is centered on a severed frame. The panels are subjected to internal pressure plus axial tension loads. The axial tension loads are equivalent to a bulkhead pressure load. Nonlinear elastic-plastic residual strength analyses of the fuselage panels are conducted using a finite element program and the crack-tip-opening-angle (CTOA) fracture criterion. Predicted crack growth and residual strength results from nonlinear analyses of the stiffened fuselage panels are compared with experimental measurements and observations. Both the test and analysis results indicate that the presence of MSD affects crack growth stability and reduces the residual strength of stiffened fuselage shells with long cracks.

  5. Vertical Drop Test of a YS-11 Fuselage Section

    NASA Astrophysics Data System (ADS)

    Minegishi, Masakatsu; Kumakura, Ikuo; Iwasaki, Kazuo; Shoji, Hirokazu; Yoshimoto, Norio; Terada, Hiroyuki; Sashikuma, Hirofumi; Isoe, Akira; Yamaoka, Toshihiro; Katayama, Noriaki; Hayashi, Toru; Akaso, Tetsuya

    The Structures and Materials Research Center of the National Aerospace Laboratory of Japan (NAL) and Kawasaki Heavy Industories, Ltd. (KHI) conducted a vertical drop test of a fuselage section cut from a NAMIC YS-11 transport airplane at NAL vertical drop test facility in December 2001. The main objectives of this program were to obtain background data for aircraft cabin safety by drop test of a full-scale fuselage section and to develop computational method for crash simulation. The test article including seats and anthropomorphic test dummies was dropped to a rigid impact surface at a velocity of 6.1 m/s (20 ft/s). The test condition and result were considered to be severe but potentially survivable. A finite element model of this test article was also developed using the explicit nonlinear transient-dynamic analysis code, LS-DYNA3D. An outline of analytical method and comparison of analysis result with drop test data are presented in this paper.

  6. Optimization of Sandwich Composites Fuselages Under Flight Loads

    NASA Astrophysics Data System (ADS)

    Yuan, Chongxin; Bergsma, Otto; Koussios, Sotiris; Zu, Lei; Beukers, Adriaan

    2012-02-01

    The sandwich composites fuselages appear to be a promising choice for the future aircrafts because of their structural efficiency and functional integration advantages. However, the design of sandwich composites is more complex than other structures because of many involved variables. In this paper, the fuselage is designed as a sandwich composites cylinder, and its structural optimization using the finite element method (FEM) is outlined to obtain the minimum weight. The constraints include structural stability and the composites failure criteria. In order to get a verification baseline for the FEM analysis, the stability of sandwich structures is studied and the optimal design is performed based on the analytical formulae. Then, the predicted buckling loads and the optimization results obtained from a FEM model are compared with that from the analytical formulas, and a good agreement is achieved. A detailed parametric optimal design for the sandwich composites cylinder is conducted. The optimization method used here includes two steps: the minimization of the layer thickness followed by tailoring of the fiber orientation. The factors comprise layer number, fiber orientation, core thickness, frame dimension and spacing. Results show that the two-step optimization is an effective method for the sandwich composites and the foam sandwich cylinder with core thickness of 5 mm and frame pitch of 0.5 m exhibits the minimum weight.

  7. Loose abrasive slurries for optical glass lapping

    SciTech Connect

    Neauport, Jerome; Destribats, Julie; Maunier, Cedric; Ambard, Chrystel; Cormont, Philippe; Pintault, B.; Rondeau, Olivier

    2010-10-20

    Loose abrasive lapping is widely used to prepare optical glass before its final polishing. We carried out a comparison of 20 different slurries from four different vendors. Slurry particle sizes and morphologies were measured. Fused silica samples were lapped with these different slurries on a single side polishing machine and characterized in terms of surface roughness and depth of subsurface damage (SSD). Effects of load, rotation speed, and slurry concentration during lapping on roughness, material removal rate, and SSD were investigated.

  8. Crash Simulation of a Vertical Drop Test of a B737 Fuselage Section with Overhead Bins and Luggage

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Fasanella, Edwin L.

    2004-01-01

    The focus of this paper is to describe a crash simulation of a 30-ft/s vertical drop test of a Boeing 737 (B737) fuselage section. The drop test of the 10-ft. long fuselage section of a B737 aircraft was conducted in November of 2000 at the FAA Technical Center in Atlantic City, NJ. The fuselage section was outfitted with two different commercial overhead stowage bins. In addition, 3,229-lbs. of luggage were packed in the cargo hold to represent a maximum take-off weight condition. The main objective of the test was to evaluate the response and failure modes of the overhead stowage bins in a narrow-body transport fuselage section when subjected to a severe, but survivable, impact. A secondary objective of the test was to generate experimental data for correlation with the crash simulation. A full-scale 3-dimensional finite element model of the fuselage section was developed and a crash simulation was conducted using the explicit, nonlinear transient dynamic code, MSC.Dytran. Pre-test predictions of the fuselage and overhead bin responses were generated for correlation with the drop test data. A description of the finite element model and an assessment of the analytical/experimental correlation are presented. In addition, suggestions for modifications to the model to improve correlation are proposed.

  9. Experimental investigations into composite fuselage impact damage resistance and post-impact compression behavior

    NASA Technical Reports Server (NTRS)

    Dost, E. F.; Finn, S. R.; Stevens, J. J.; Lin, K. Y.; Fitch, C. E.

    1992-01-01

    Impact damage resistance and residual strength of laminated composite transport aircraft fuselage structure was studied experimentally. Techniques to quantify impact damage discretely and non-discretely are described. Experimental techniques to three-dimensionally map matrix damage and determine the sublaminate structure are illustrated. Impact damage was also quantified non-discretely, using characteristics of flexural wave propagation. Strain distributions in compressively loaded impact damaged laminates were experimentally measured.

  10. Noise control mechanisms of inside aircraft

    NASA Astrophysics Data System (ADS)

    Zverev, A. Ya.

    2016-07-01

    World trends in the development of methods and approaches to noise reduction in aircraft cabins are reviewed. The paper discusses the mechanisms of passive and active noise and vibration control, application of "smart" and innovative materials, new approaches to creating all fuselage-design elements, and other promising directions of noise control inside aircraft.

  11. Computational investigation of slot blowing for fuselage forebody flow control

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Rizk, Yehia M.; Schiff, Lewis B.; Cummings, Russell M.

    1992-01-01

    This paper presents a computational investigation of a tangential slot blowing concept for generating lateral control forces on an aircraft fuselage forebody. The effects of varying both the jet width and jet exit velocity for a fixed location slot are analyzed. This work is aimed at aiding researchers in designing future experimental and computational models of tangential slot blowing. The primary influence on the resulting side force of the forebody is seen to be the jet mass flow rate. This influence is sensitive to different combinations of slot widths and jet velocities over the range of variables considered. Both an actuator plane and an overset grid technique are used to model the tangential slot. The overset method successfully resolves the details of the actual slot geometry, extending the generality of the numerical method. The actuator plane concept predicts side forces similar to those produced by resolving the actual slot geometry.

  12. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles: Structural analysis

    NASA Technical Reports Server (NTRS)

    Baker, A. H.

    1975-01-01

    The effects of fuselage cross-section (circular and elliptical) and structural arrangement (integral and nonintegral tanks) on the performance of actively cooled hypersonic cruise vehicles was evaluated. It was found that integrally machined stiffening of the tank walls, while providing the most weight-efficient use of materials, results in higher production costs. Fatigue and fracture mechanics appeared to have little effect on the weight of the three study aircraft. The need for thermal strain relief through insulation is discussed. Aircraft size and magnitude of the internal pressure are seen to be significant factors in tank design.

  13. Advanced technology composite aircraft structures

    NASA Technical Reports Server (NTRS)

    Ilcewicz, Larry B.; Walker, Thomas H.

    1991-01-01

    Work performed during the 25th month on NAS1-18889, Advanced Technology Composite Aircraft Structures, is summarized. The main objective of this program is to develop an integrated technology and demonstrate a confidence level that permits the cost- and weight-effective use of advanced composite materials in primary structures of future aircraft with the emphasis on pressurized fuselages. The period from 1-31 May 1991 is covered.

  14. Full scale GLARE fuselage panel tests

    NASA Technical Reports Server (NTRS)

    Vercammen, Roland W. A.; Ottens, Harold H.

    1996-01-01

    A GLARE fuselage panel, representative of the crown section of the Fokker 100 fuselage in front of the wing, was tested. The panels were loaded by air pressure resulting in tangential stress in the panel by axial loading, representative of both the cabin pressure and the fuselage bending due to taxiing and gust loading. A fatigue test, simulating 180000 flights, followed by static tests were performed. The panel was loaded to failure at 1.32 ultimate load. The test set-up, the uniform strain distribution of the panel, and the fatigue loads applied at high test frequency are described. The use of GLARE leads to a substantial weight reduction without affecting the fatigue static strength.

  15. A NASTRAN model of a large flexible swing-wing bomber. Volume 4: NASTRAN model development-fuselage structure

    NASA Technical Reports Server (NTRS)

    Mock, W. D.; Latham, R. A.

    1982-01-01

    The NASTRAN model plan for the fuselage structure was expanded in detail to generate the NASTRAN model for this substructure. The grid point coordinates were coded for each element. The material properties and sizing data for each element were specified. The fuselage substructure model was thoroughly checked out for continuity, connectivity, and constraints. This substructure was processed for structural influence coefficients (SIC) point loadings and the deflections were compared to those computed for the aircraft detail model. Finally, a demonstration and validation processing of this substructure was accomplished using the NASTRAN finite element program. The bulk data deck, stiffness matrices, and SIC output data were delivered.

  16. A three-dimensional, compressible, laminar boundary-layer method for general fuselages. Volume 1: Numerical method

    NASA Technical Reports Server (NTRS)

    Wie, Yong-Sun

    1990-01-01

    A procedure for calculating 3-D, compressible laminar boundary layer flow on general fuselage shapes is described. The boundary layer solutions can be obtained in either nonorthogonal 'body oriented' coordinates or orthogonal streamline coordinates. The numerical procedure is 'second order' accurate, efficient and independent of the cross flow velocity direction. Numerical results are presented for several test cases, including a sharp cone, an ellipsoid of revolution, and a general aircraft fuselage at angle of attack. Comparisons are made between numerical results obtained using nonorthogonal curvilinear 'body oriented' coordinates and streamline coordinates.

  17. Interactive Inverse Design Optimization of Fuselage Shape for Low-Boom Supersonic Concepts

    NASA Technical Reports Server (NTRS)

    Li, Wu; Shields, Elwood; Le, Daniel

    2008-01-01

    This paper introduces a tool called BOSS (Boom Optimization using Smoothest Shape modifications). BOSS utilizes interactive inverse design optimization to develop a fuselage shape that yields a low-boom aircraft configuration. A fundamental reason for developing BOSS is the need to generate feasible low-boom conceptual designs that are appropriate for further refinement using computational fluid dynamics (CFD) based preliminary design methods. BOSS was not developed to provide a numerical solution to the inverse design problem. Instead, BOSS was intended to help designers find the right configuration among an infinite number of possible configurations that are equally good using any numerical figure of merit. BOSS uses the smoothest shape modification strategy for modifying the fuselage radius distribution at 100 or more longitudinal locations to find a smooth fuselage shape that reduces the discrepancies between the design and target equivalent area distributions over any specified range of effective distance. For any given supersonic concept (with wing, fuselage, nacelles, tails, and/or canards), a designer can examine the differences between the design and target equivalent areas, decide which part of the design equivalent area curve needs to be modified, choose a desirable rate for the reduction of the discrepancies over the specified range, and select a parameter for smoothness control of the fuselage shape. BOSS will then generate a fuselage shape based on the designer's inputs in a matter of seconds. Using BOSS, within a few hours, a designer can either generate a realistic fuselage shape that yields a supersonic configuration with a low-boom ground signature or quickly eliminate any configuration that cannot achieve low-boom characteristics with fuselage shaping alone. A conceptual design case study is documented to demonstrate how BOSS can be used to develop a low-boom supersonic concept from a low-drag supersonic concept. The paper also contains a study

  18. An examination of faying surface fretting in single lap splices

    NASA Astrophysics Data System (ADS)

    Brown, Adam

    While fretting damage in mechanically fastened joints is widely acknowledged as a common source of crack nucleation, little work is available in the open literature on the role that fretting damage plays in the fatigue life of a riveted joint. To expand on the limited knowledge available, a study was undertaken on fretting fatigue in thin-sheet riveted fuselage lap joints. In joints constructed out of 1 mm thick 2024-T3 aluminum sheet the rivet forming load was found to have a significant effect on the location of fretting damage and crack nucleation. This effect was observed for splices riveted with machine countersunk and with universal rivets. The shift in the location of peak fretting damage and crack nucleation with changing rivet forming loads was investigated through numerical and experimental methods. A predictive model based on the critical plane Smith-Watson-Topper strain life equation was applied to the complex geometry of the single lap splice and was shown to be effective in predicting the fretting fatigue life as well as the location of fretting-induced crack nucleation. Basing this model on an explicit finite element simulation allowed for the inclusion of compressive residual stresses generated during rivet forming. Key to the proper functionality of the predictive model was to have a validated finite element model from which results for the stress and strain field in the loaded component could be obtained. In addition to the predictive model, a series of splice coupon and simplified geometry fretting fatigue tests were performed. The tests showed that, at higher rivet forming loads, crack nucleation is on the faying surface away from the hole edge and that the type of surface condition is important to the fretting fatigue life of the splice. The discovery of this variation with surface treatment at high rivet forming loads is important as more research is showing the benefit of using load-controlled rivet forming and higher rivet forming loads in

  19. Textile composite fuselage structures development

    NASA Technical Reports Server (NTRS)

    Jackson, Anthony C.; Barrie, Ronald E.; Chu, Robert L.

    1993-01-01

    Phase 2 of the NASA ACT Contract (NAS1-18888), Advanced Composite Structural Concepts and Materials Technology for Transport Aircraft Structures, focuses on textile technology, with resin transfer molding or powder coated tows. The use of textiles has the potential for improving damage tolerance, reducing cost and saving weight. This program investigates resin transfer molding (RTM), as a maturing technology for high fiber volume primary structures and powder coated tows as an emerging technology with a high potential for significant cost savings and superior structural properties. Powder coated tow technology has promise for significantly improving the processibility of high temperature resins such as polyimides.

  20. Aircraft empennage structural detail design

    NASA Technical Reports Server (NTRS)

    Meholic, Greg; Brown, Rhonda; Hall, Melissa; Harvey, Robert; Singer, Michael; Tella, Gustavo

    1993-01-01

    This project involved the detailed design of the aft fuselage and empennage structure, vertical stabilizer, rudder, horizontal stabilizer, and elevator for the Triton primary flight trainer. The main design goals under consideration were to illustrate the integration of the control systems devices used in the tail surfaces and their necessary structural supports as well as the elevator trim, navigational lighting system, electrical systems, tail-located ground tie, and fuselage/cabin interface structure. Accommodations for maintenance, lubrication, adjustment, and repairability were devised. Weight, fabrication, and (sub)assembly goals were addressed. All designs were in accordance with the FAR Part 23 stipulations for a normal category aircraft.

  1. Quadruple Lap Shear Processing Evaluation

    NASA Technical Reports Server (NTRS)

    Thornton, Tony N.; McCool, A. (Technical Monitor)

    2000-01-01

    The Thiokol, Science and Engineering Huntsville Operations (SEHO) Laboratory has previously experienced significant levels of variation in testing Quadruple Lap Shear (QLS) specimens. The QLS test is used at Thiokol / Utah for the qualification of Reusable Solid Rocket Motor (RSRM) nozzle flex bearing materials. A test was conducted to verify that process changes instituted by SEHO personnel effectively reduced variability, even with normal processing variables introduced. A test matrix was designed to progress in a series of steps; the first establishing a baseline, then introducing additional solvents or other variables. Variables included normal test plan delay times, pre-bond solvent hand-wipes and contaminants. Each condition tested utilized standard QLS hardware bonded with natural rubber, two separate technicians and three replicates. This paper will report the results and conclusions of this investigation.

  2. Design and Evaluation of Composite Fuselage Panels Subjected to Combined Loading Conditions

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Rouse, Marshall

    1998-01-01

    Methodologies used in industry for designing transport aircraft composite fuselage structures are discussed. Several aspects of the design methodologies are based on assumptions from metallic fuselage technology which requires that full-scale structures be tested with the actual loading conditions to validate the designs. Composite panels which represent crown and side regions of a fuselage structure are designed using this approach and tested in biaxial tension. Descriptions of the state-of-the-art test facilities used for this structural evaluation are presented. These facilities include a pressure-box test machine and a D-box test fixture in a combined loads test machine which are part of a Combined Loads Test System (COLTS). Nonlinear analysis results for a reference shell and a stiffened composite panel tested in the pressure-box test machine with and without damage are presented. The analytical and test results are compared to assess the ability of the pressure-box test machine to simulate a shell stress state with and without damage. A combined loads test machine for testing aircraft primary structures is described. This test machine includes a D-box test fixture to accommodate curved stiffened panels and the design features of this test fixture are presented. Finite element analysis results for a curved panel to be tested in the D-box test fixture are also discussed.

  3. Study of utilization of advanced composites in fuselage structures of large transports

    NASA Technical Reports Server (NTRS)

    Jackson, A. C.; Campion, M. C.; Pei, G.

    1984-01-01

    The effort required by the transport aircraft manufacturers to support the introduction of advanced composite materials into the fuselage structure of future commercial and military transport aircraft is investigated. Technology issues, potential benefits to military life cycle costs and commercial operating costs, and development plans are examined. The most urgent technology issues defined are impact dynamics, acoustic transmission, pressure containment and damage tolerance, post-buckling, cutouts, and joints and splices. A technology demonstration program is defined and a rough cost and schedule identified. The fabrication and test of a full-scale fuselage barrel section is presented. Commercial and military benefits are identified. Fuselage structure weight savings from use of advanced composites are 16.4 percent for the commercial and 21.8 percent for the military. For the all-composite airplanes the savings are 26 percent and 29 percent, respectively. Commercial/operating costs are reduced by 5 percent for the all-composite airplane and military life cycle costs by 10 percent.

  4. On the Strength of Box Type Fuselages

    NASA Technical Reports Server (NTRS)

    Mathar, J

    1929-01-01

    The present investigation relates to a box-type fuselage with sides consisting of thin smooth sheet metal, stiffened by longitudinal members riveted to the flanged channel-section bulkheads or transverse frames and to the semicircular corrugated corner stiffenings. The results obtained in this particular case can be applied to a great number of similar structures.

  5. Astronaut Eileen Collins in Full Fuselage Trainer

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Astronaut Eileen M. Collins, pilot for the STS-63 mission, participates in STS-63 training at JSC's Shuttle mockup and integration laboratory. Collins is seated at the pilot's station in the Full Fuselage Trainer (FFT) (48403-4); Collins looks out the aft flight deck window in the Shuttle mockup trainer (48405).

  6. The Aerodynamic Aspect of Wing-fuselage Fillets

    NASA Technical Reports Server (NTRS)

    Muttray, H

    1935-01-01

    Model tests prove the feasibility of enhancing the aerodynamic qualities of wing-fuselage fillets by appropriate design of fuselage and wing roots. Abrupt changes from maximum fuselage height to wing chord must be avoided and every longitudinal section of fuselage and wing roots must be so faired and arranged as to preserve the original lift distribution of the continuous wing. Adapting the fuselage to the curvilinear circulation of the wing affords further improvement. The polars of such arrangements are almost the same as those of the "wing alone," thus voiding the superiority of the high-wing type airplane known with conventional design.

  7. Summary of AH-1G flight vibration data for validation of coupled rotor-fuselage analyses

    NASA Technical Reports Server (NTRS)

    Dompka, R. V.; Cronkhite, J. D.

    1986-01-01

    Under a NASA research program designated DAMVIBS (Design Analysis Methods for VIBrationS), four U. S. helicopter industry participants (Bell Helicopter, Boeing Vertol, McDonnell Douglas Helicopter, and Sikorsky Aircraft) are to apply existing analytical methods for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. Bell Helicopter, as the manufacturer of the AH-1G, was asked to provide pertinent rotor data and to collect the OLS flight vibration data needed to perform the correlations. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM) developed by Bell which has been extensively documented and correlated with ground vibration tests.The AH-1G FEM was provided to each of the participants for use in their coupled rotor-fuselage analyses. This report describes the AH-1G OLS flight test program and provides the flight conditions and measured vibration data to be used by each participant in their correlation effort. In addition, the mechanical, structural, inertial and aerodynamic data for the AH-1G two-bladed teetering main rotor system are presented. Furthermore, modifications to the NASTRAN FEM of the fuselage structure that are necessary to make it compatible with the OLS test article are described. The AH-1G OLS flight test data was found to be well documented and provide a sound basis for evaluating currently existing analysis methods used for calculation of coupled rotor-fuselage vibrations.

  8. Experimental and analytical investigations of fuselage modal characteristics and structural-acoustic coupling

    NASA Technical Reports Server (NTRS)

    Simpson, Myles A.; Mathur, Gopal P.

    1992-01-01

    Measurements conducted on a DC-9 aircraft test section to define the shell and cavity modes of the fuselage, understand its structural-acoustic coupling characteristics, and measure its response to different types of acoustic and vibration excitations are reported. The data were processed to generate spatial plots and wavenumber maps of the shell acceleration and cabin acoustic pressure field. Analysis and interpretation of the spatial plots and wavenumber maps showed that the only structural-acoustic coupling occurred at 105 Hz between the N=2 circumferential structural mode and the (n=2, p=0) circumferential cavity mode. The fuselage response to vibration excitation was found to be dominated by modes whose order increases with frequency.

  9. Unsteady transonic potential flow over a flexible fuselage

    NASA Technical Reports Server (NTRS)

    Gibbons, Michael D.

    1993-01-01

    A flexible fuselage capability has been developed and implemented within version 1.2 of the CAP-TSD code. The capability required adding time dependent terms to the fuselage surface boundary conditions and the fuselage surface pressure coefficient. The new capability will allow modeling the effect of a flexible fuselage on the aeroelastic stability of complex configurations. To assess the flexible fuselage capability several steady and unsteady calculations have been performed for slender fuselages with circular cross-sections. Steady surface pressures are compared with experiment at transonic flight conditions. Unsteady cross-sectional lift is compared with other analytical results at a low subsonic speed and a transonic case has been computed. The comparisons demonstrate the accuracy of the flexible fuselage modifications.

  10. Impact damage resistance of composite fuselage structure, part 2

    NASA Technical Reports Server (NTRS)

    Dost, Ernest F.; Finn, Scott R.; Murphy, Daniel P.; Huisken, Amy B.

    1993-01-01

    The strength of laminated composite materials may be significantly reduced by foreign object impact induced damage. An understanding of the damage state is required in order to predict the behavior of structure under operational loads or to optimize the structural configuration. Types of damage typically induced in laminated materials during an impact event include transverse matrix cracking, delamination, and/or fiber breakage. The details of the damage state and its influence on structural behavior depend on the location of the impact. Damage in the skin may act as a soft inclusion or affect panel stability, while damage occurring over a stiffener may include debonding of the stiffener flange from the skin. An experiment to characterize impact damage resistance of fuselage structure as a function of structural configuration and impact threat was performed. A wide range of variables associated with aircraft fuselage structure such as material type and stiffener geometry (termed, intrinsic variables) and variables related to the operating environment such as impactor mass and diameter (termed, extrinsic variables) were studied using a statistically based design-of-experiments technique. The experimental design resulted in thirty-two different 3-stiffener panels. These configured panels were impacted in various locations with a number of impactor configurations, weights, and energies. The results obtained from an examination of impacts in the skin midbay and hail simulation impacts are documented. The current discussion is a continuation of that work with a focus on nondiscrete characterization of the midbay hail simulation impacts and discrete characterization of impact damage for impacts over the stiffener.

  11. Propeller aircraft interior noise model

    NASA Technical Reports Server (NTRS)

    Pope, L. D.; Wilby, E. G.; Wilby, J. F.

    1984-01-01

    An analytical model was developed to predict the interior noise of propeller-driven aircraft. The fuselage model is that of a cylinder with a structurally-integral floor. The cabin sidewall is stiffened by stringers and ring frames, and the floor by longitudinal beams. The cabin interior is covered with a sidewall treatments consisting of layers of porous material and an impervious trim septum. Representation of the propeller pressure field is utilized as input data in the form of the propeller noise signature at a series of locations on a grid over the fuselage structure. Results obtained from the analytical model are compared with test data measured by NASA in a scale model cylindrical fuselage excited by a model propeller.

  12. Secondary Wing System for Use on an Aircraft

    NASA Technical Reports Server (NTRS)

    Smith, Brian E. (Inventor)

    1999-01-01

    A secondary wing system for use on an aircraft augments the lift, stability, and control of the aircraft at subsonic speeds. The secondary wing system includes a mechanism that allows the canard to be retracted within the contour of the aircraft fuselage from an operational position to a stowed position. The top surface of the canard is exposed to air flow in the stowed position, and is contoured to integrate aerodynamically and smoothly within the contour of the fuselage when the canard is retracted for high speed flight. The bottom portion of the canard is substantially flat for rotation into a storage recess within the fuselage. The single canard rotates about a vertical axis at its spanwise midpoint. The canard can be positioned between a range of sweep angles during flight and a stowed position in which its span is substantially parallel to the aircraft fuselage. The canard can be deployed and retracted during flight. The deployment mechanism includes a circular mounting ring and drive mechanism that connects the canard with the fuselage and permits it to rotate and to change incidence. The deployment mechanism further includes retractable fairings which serve to streamline the wing when it is retracted into the top of the fuselage.

  13. Large-Scale Advanced Prop-Fan (LAP)

    NASA Technical Reports Server (NTRS)

    Degeorge, C. L.

    1988-01-01

    In recent years, considerable attention has been directed toward improving aircraft fuel efficiency. Analytical studies and research with wind tunnel models have demonstrated that the high inherent efficiency of low speed turboprop propulsion systems may now be extended to the Mach .8 flight regime of today's commercial airliners. This can be accomplished with a propeller, employing a large number of thin highly swept blades. The term Prop-Fan has been coined to describe such a propulsion system. In 1983 the NASA-Lewis Research Center contracted with Hamilton Standard to design, build and test a near full scale Prop-Fan, designated the Large Scale Advanced Prop-Fan (LAP). This report provides a detailed description of the LAP program. The assumptions and analytical procedures used in the design of Prop-Fan system components are discussed in detail. The manufacturing techniques used in the fabrication of the Prop-Fan are presented. Each of the tests run during the course of the program are also discussed and the major conclusions derived from them stated.

  14. LAPS Grid generation and adaptation

    NASA Astrophysics Data System (ADS)

    Pagliantini, Cecilia; Delzanno, Gia Luca; Guo, Zehua; Srinivasan, Bhuvana; Tang, Xianzhu; Chacon, Luis

    2011-10-01

    LAPS uses a common-data framework in which a general purpose grid generation and adaptation package in toroidal and simply connected domains is implemented. The initial focus is on implementing the Winslow/Laplace-Beltrami method for generating non-overlapping block structured grids. This is to be followed by a grid adaptation scheme based on Monge-Kantorovich optimal transport method [Delzanno et al., J. Comput. Phys,227 (2008), 9841-9864], that equidistributes application-specified error. As an initial set of applications, we will lay out grids for an axisymmetric mirror, a field reversed configuration, and an entire poloidal cross section of a tokamak plasma reconstructed from a CMOD experimental shot. These grids will then be used for computing the plasma equilibrium and transport in accompanying presentations. A key issue for Monge-Kantorovich grid optimization is the choice of error or monitor function for equi-distribution. We will compare the Operator Recovery Error Source Detector (ORESD) [Lapenta, Int. J. Num. Meth. Eng,59 (2004) 2065-2087], the Tau method and a strategy based on the grid coarsening [Zhang et al., AIAA J,39 (2001) 1706-1715] to find an ``optimal'' grid. Work supported by DOE OFES.

  15. Novel Composites for Wing and Fuselage Applications

    NASA Technical Reports Server (NTRS)

    Suarez, J. A.; Buttitta, C.

    1996-01-01

    Design development was successfully completed for textile preforms with continuous cross-stiffened epoxy panels with cut-outs. The preforms developed included 3-D angle interlock weaving of graphite structural fibers impregnated by resin film infiltration (RFI) and shown to be structurally suitable under conditions requiring minimum acquisition costs. Design guidelines/analysis methodology for such textile structures are given. The development was expanded to a fuselage side-panel component of a subsonic commercial airframe and found to be readily scalable. The successfully manufactured panel was delivered to NASA Langley for biaxial testing. This report covers the work performed under Task 3 -- Cross-Stiffened Subcomponent; Task 4 -- Design Guidelines/Analysis of Textile-Reinforced Composites; and Task 5 -- Integrally Woven Fuselage Panel.

  16. Airborne Synthetic Aperature Radar (AIRSAR) on left rear fuselage of DC-8 Airborne Laboratory

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A view of the Airborne Synthetic Aperature Radar (AIRSAR) antenna on the left rear fuselage of the DC-8. The AIRSAR captures images of the ground from the side of the aircraft and can provide precision digital elevation mapping capabilities for a variety of studies. The AIRSAR is one of a number of research systems that have been added to the DC-8. NASA is using a DC-8 aircraft as a flying science laboratory. The platform aircraft, based at NASA's Dryden Flight Research Center, Edwards, Calif., collects data for many experiments in support of scientific projects serving the world scientific community. Included in this community are NASA, federal, state, academic and foreign investigators. Data gathered by the DC-8 at flight altitude and by remote sensing have been used for scientific studies in archeology, ecology, geography, hydrology, meteorology, oceanography, volcanology, atmospheric chemistry, soil science and biology.

  17. Composite fuselage crown panel manufacturing technology

    NASA Technical Reports Server (NTRS)

    Willden, Kurtis; Metschan, S.; Grant, C.; Brown, T.

    1992-01-01

    Commercial fuselage structures contain significant challenges in attempting to save manufacturing costs with advanced composite technology. Assembly issues, material costs, and fabrication of elements with complex geometry are each expected to drive the cost of composite fuselage structures. Boeing's efforts under the NASA ACT program have pursued key technologies for low-cost, large crown panel fabrication. An intricate bond panel design and manufacturing concepts were selected based on the efforts of the Design Build Team (DBT). The manufacturing processes selected for the intricate bond design include multiple large panel fabrication with the Advanced Tow Placement (ATP) process, innovative cure tooling concepts, resin transfer molding of long fuselage frames, and utilization of low-cost material forms. The process optimization for final design/manufacturing configuration included factory simulations and hardware demonstrations. These efforts and other optimization tasks were instrumental in reducing cost by 18 percent and weight by 45 percent relative to an aluminum baseline. The qualitative and quantitative results of the manufacturing demonstrations were used to assess manufacturing risks and technology readiness.

  18. Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1998-01-01

    The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

  19. Airbag system and method for facilitating emergency egress from an aircraft

    NASA Technical Reports Server (NTRS)

    Rawdon, Blaine K. (Inventor); Hawley, Arthur V. (Inventor)

    2002-01-01

    An airbag system for elevating the fuselage of an aircraft off a landing surface a sufficient degree to allow for emergency egress of passengers and crew through ventral emergency exit doors. An airbag assembly made up of a plurality of independent airbags is disposed within the aircraft. When activated, the airbag system deploys the airbags external of the aircraft that elevate the fuselage of the aircraft a sufficient degree to allow for utilizing the ventral emergency exit doors on the fuselage to enable evacuating the passengers and crew. An activation mechanism is connected to the inflation.devices associated with each of the airbags. The activation mechanism generates an electrical signal which activates the inflation devices, which in turn fill the airbags with a compressed fluid, thus expanding the airbags and lifting the fuselage. A crew member initiates the activation of the airbag system through one or more switches.

  20. Nonlinear and progressive failure aspects of transport composite fuselage damage tolerance

    NASA Technical Reports Server (NTRS)

    Walker, Tom; Ilcewicz, L.; Murphy, Dan; Dopker, Bernhard

    1993-01-01

    The purpose is to provide an end-user's perspective on the state of the art in life prediction and failure analysis by focusing on subsonic transport fuselage issues being addressed in the NASA/Boeing Advanced Technology Composite Aircraft Structure (ATCAS) contract and a related task-order contract. First, some discrepancies between the ATCAS tension-fracture test database and classical prediction methods is discussed, followed by an overview of material modeling work aimed at explaining some of these discrepancies. Finally, analysis efforts associated with a pressure-box test fixture are addressed, as an illustration of modeling complexities required to model and interpret tests.

  1. Nonlinear and progressive failure aspects of transport composite fuselage damage tolerance

    NASA Astrophysics Data System (ADS)

    Walker, Tom; Ilcewicz, L.; Murphy, Dan; Dopker, Bernhard

    1993-10-01

    The purpose is to provide an end-user's perspective on the state of the art in life prediction and failure analysis by focusing on subsonic transport fuselage issues being addressed in the NASA/Boeing Advanced Technology Composite Aircraft Structure (ATCAS) contract and a related task-order contract. First, some discrepancies between the ATCAS tension-fracture test database and classical prediction methods is discussed, followed by an overview of material modeling work aimed at explaining some of these discrepancies. Finally, analysis efforts associated with a pressure-box test fixture are addressed, as an illustration of modeling complexities required to model and interpret tests.

  2. A fuselage/tank structure study for actively cooled hypersonic cruise vehicles: Active cooling system analysis

    NASA Technical Reports Server (NTRS)

    Stone, J. E.

    1975-01-01

    The effects of fuselage cross section and structural arrangement on the performance of actively cooled hypersonic cruise vehicles are investigated. An active cooling system which maintains the aircraft's entire surface area at temperatures below 394 K at Mach 6 is developed along with a hydrogen fuel tankage thermal protection system. Thermodynamic characteristics of the actively cooled thermal protection systems established are summarized. Design heat loads and coolant flowrate requirements are defined for each major structural section and for the total system. Cooling system weights are summarized at the major component level. Conclusions and recommendations are included.

  3. Hybrid Wing-Body (HWB) Pressurized Fuselage Modeling, Analysis, and Design for Weight Reduction

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    2012-01-01

    This paper describes the interim progress for an in-house study that is directed toward innovative structural analysis and design of next-generation advanced aircraft concepts, such as the Hybrid Wing-Body (HWB) and the Advanced Mobility Concept-X flight vehicles, for structural weight reduction and associated performance enhancement. Unlike the conventional, skin-stringer-frame construction for a cylindrical fuselage, the box-type pressurized fuselage panels in the HWB undergo significant deformation of the outer aerodynamic surfaces, which must be minimized without significant structural weight penalty. Simple beam and orthotropic plate theory is first considered for sizing, analytical verification, and possible equivalent-plate analysis with appropriate simplification. By designing advanced composite stiffened-shell configurations, significant weight reduction may be possible compared with the sandwich and ribbed-shell structural concepts that have been studied previously. The study involves independent analysis of the advanced composite structural concepts that are presently being developed by The Boeing Company for pressurized HWB flight vehicles. High-fidelity parametric finite-element models of test coupons, panels, and multibay fuselage sections, were developed for conducting design studies and identifying critical areas of potential failure. Interim results are discussed to assess the overall weight/strength advantages.

  4. Wireless Local Area Network Performance Inside Aircraft Passenger Cabins

    NASA Technical Reports Server (NTRS)

    Whetten, Frank L.; Soroker, Andrew; Whetten, Dennis A.; Whetten, Frank L.; Beggs, John H.

    2005-01-01

    An examination of IEEE 802.11 wireless network performance within an aircraft fuselage is performed. This examination measured the propagated RF power along the length of the fuselage, and the associated network performance: the link speed, total throughput, and packet losses and errors. A total of four airplanes: one single-aisle and three twin-aisle airplanes were tested with 802.11a, 802.11b, and 802.11g networks.

  5. An unsteady helicopter rotor-fuselage aerodynamic interaction analysis

    NASA Technical Reports Server (NTRS)

    Lorber, Peter F.; Egolf, T. Alan

    1990-01-01

    A computational method has been developed to treat the unsteady aerodynamic interaction between a helicopter rotor, wake, and fuselage. Two existing codes, a lifting line-prescribed wake rotor analysis and a source panel fuselage analysis, were modified and coupled to allow prediction of unsteady fuselage pressures and airloads. A prescribed displacement technique was developed to position the rotor wake about the fuselage. Also coupled into the method were optional blade dynamics or rigid blade performance analyses to set the rotor operating conditions. Sensitivity studies were performed to determine the influence of the wake and fuselage geometry on the computational results. Solutions were computed for an ellipsoidal fuselage and a four bladed rotor at several advance ratios, using both the classical helix and the generalized distorted wake model. Results are presented that describe the induced velocities, pressures, and airloads on the fuselage and the induced velocities and bound circulation at the rotor. The ability to treat arbitrary geometries was demonstrated using a simulated helicopter fuselage. Initial computations were made to simulate the geometry of an experimental rotor-fuselage interaction study performed at the Georgia Institute of Technology.

  6. Drag of Exposed Fittings and Surface Irregularities on Airplane Fuselages

    NASA Technical Reports Server (NTRS)

    Wood, Donald H

    1928-01-01

    Measurements of drag were made on fittings taken from a typical fuselage to determine whether the difference between the observed full size fuselage drag and model fuselage drag could be attributed to the effects of fittings and surface irregularities found on the full size fuselage and not on the model. There are wide variations in the drag coefficients for the different fittings. In general those which protrude little from the surface or are well streamlined show very low and almost negligible drag. The measurements show, however, that a large part of the difference between model and full scale test results may be attributed to these fittings.

  7. Evaluation of Isolated Fuselage and Rotor-Fuselage Interaction Using CFD

    NASA Technical Reports Server (NTRS)

    Renaud, Thomas; O'Brien, David; Smith, Marilyn; Potsdam, Mark

    2004-01-01

    The US Army Aeroflightdynamics Directorate (AFDD), the French Office National d'Etudes et de Recherches Aerospatiales (ONERA) and the Georgia Institute of Technology (GIT) are working under the United States/France Memorandum of Agreement on Helicopter Aeromechanics to study rotorcraft aeromechanics issues of interest to both nations. As a task under this agreement, a comparative study of the Dauphin 365N helicopter has been undertaken to analyze the capabilities and weaknesses of state-of-the-art computational fluid dynamics (CFD) codes, with the aim of fuselage performance prediction and investigation of rotor-fuselage interaction. Three CFD flow solvers applied on three meshes provide similar results in terms of pressure coefficient. Force predictions vary somewhat. This paper presents details on the grid sensitivity and the low Mach number preconditioning influence. The importance of taking into account the wind tunnel strut and the rotor hub is shown. The pressure coefficients along top and bottom centerlines of the fuselage are in good agreement with the experiment except in the area aft of the hub. There remains a discrepancy between the computed forces and the experimental data due in part to modeling inaccuracies. Rotor- fuselage interactions are performed using uniform and non-uniform actuator disk models in order to simulate the rotor downwash.

  8. Enhancing pulsed eddy current for inspection of P-3 Orion lap-joint structures

    NASA Astrophysics Data System (ADS)

    Butt, D. M.; Underhill, P. R.; Krause, T. W.

    2016-02-01

    During flight, aircraft are subjected to cyclic loading. In the Lockheed P-3 Orion airframe, this cyclic loading can lead to development of fatigue cracks at steel fastener locations in the top and second layers of aluminum wing skin lap-joints. An inspection method that is capable of detecting these cracks, without fastener removal, is desirable as this can minimize aircraft downtime, while subsequently reducing the risk of collateral damage. The ability to detect second layer cracks has been demonstrated using a Pulsed Eddy Current (PEC) probe design that utilizes the ferrous fastener as a flux conduit. This allows for deeper penetration of flux into the lap-joint second layer and consequently, sensitivity to the presence of cracks. Differential pick-up coil pairs are used to sense the eddy current response due to the presence of a crack. The differential signal obtained from pick-up coils on opposing sides of the fastener is analyzed using a Modified Principal Components Analysis (MPCA). This is followed by a cluster analysis of the resulting MPCA scores to separate fastener locations with cracks from those without. Probe design features, data acquisition system parameters and signal post-processing can each have a strong impact on crack detection. Physical probe configurations and signal analysis processes, used to enhance the PEC system for detection of cracks in P-3 Orion lap-joint structures, are investigated and an enhanced probe design is identified.

  9. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Lap-joint seam boilers. 230.30 Section 230.30... Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... annual inspection so that an inspection of the entire joint, inside and out, can be made, taking...

  10. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Lap-joint seam boilers. 230.30 Section 230.30... Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... annual inspection so that an inspection of the entire joint, inside and out, can be made, taking...

  11. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Lap-joint seam boilers. 230.30 Section 230.30... Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... annual inspection so that an inspection of the entire joint, inside and out, can be made, taking...

  12. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Lap-joint seam boilers. 230.30 Section 230.30... Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal seams... annual inspection so that an inspection of the entire joint, inside and out, can be made, taking...

  13. 49 CFR 230.30 - Lap-joint seam boilers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Lap-joint seam boilers. 230.30 Section 230.30..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Inspection and Repair § 230.30 Lap-joint seam boilers. Every boiler having lap-joint longitudinal...

  14. A 0.15-scale study of configuration effects on the aerodynamic interaction between main rotor and fuselage

    NASA Technical Reports Server (NTRS)

    Trept, Ted

    1984-01-01

    Hover and forward flight tests were conducted to investigate the mutual aerodynamic interaction between the main motor and fuselage of a conventional helicopter configuration. A 0.15-scale Model 222 two-bladed teetering rotor was combined with a 0.15-scale model of the NASA Ames 40x80-foot wind tunnel 1500 horsepower test stand fairing. Configuration effects were studied by modifying the fairing to simulate a typical helicopter forebody. Separation distance between rotor and body were also investigated. Rotor and fuselage force and moment as well as pressure data are presented in graphical and tabular format. Data was taken over a range of thrust coefficients from 0.002 to 0.007. In forward flight speed ratio was varied from 0.1 to 0.3 with shaft angle varying from +4 to -12 deg. The data show that the rotors effect on the fuselage may be considerably more important to total aircraft performance than the effect of the fuselage on the rotor.

  15. VIEW OF BOEING 737200 FUSELAGE FROM TOP LEVEL OF TAIL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BOEING 737-200 FUSELAGE FROM TOP LEVEL OF TAIL DOCK AND. A NEW SAFETY CABLE FROM THE TAIL DOCK WILL ALLOW INSPECTORS TO WALK UP AND DOWN THE FUSELAGE TO CHECK FOR CRACKS OR MISSING FASTENERS. - Greater Buffalo International Airport, Maintenance Hangar, Buffalo, Erie County, NY

  16. Enhancing commerical aircraft explosion survivability via active venting

    NASA Astrophysics Data System (ADS)

    Veldman, Roger Lee

    2001-10-01

    A new technique for enhancing aircraft safety in the event of an on-board explosion was studied. The method under study employs deployable vent panels located on the fuselage which are activated by an array of pressure sensors in the aircraft interior. In the event that an explosion is detected, appropriate vent panels are rapidly released from the aircraft. This approach seeks to provide timely relief of explosive pressures within an aircraft to prevent catastrophic structural failure. In this study, the approximate time scale of an explosive detonation and the subsequent sensing and electronic processing was determined. Then, the actuation response times of several vent panel systems were determined through analytical modeling and scale-model experimental testing with good correlation achieved. A scale-model experimental analysis was also conducted to determine the decompression venting time of an aircraft fuselage under a variety of conditions. Two different sized pressure vessels were used in the experimental work and the results correlated quite favorably with an analytical model for decompression times. Finally, a dynamic finite element analysis was conducted to determine the response of a portion of a typical commercial aircraft fuselage subjected to explosive pressure loading. It was determined from this analysis that the pre-stressing of the fuselage from cabin pressurization increases the damage vulnerability of a commercial aircraft fuselage to internal explosions. It was also learned from the structural analysis that the peak fuselage strains due to blast loading occur quickly (within approximately 2 milliseconds) while it was conservatively estimated that approximately 5 to 7 milliseconds would be required to sense the explosion, to actuate selected vent panels, and to initiate the release of cabin pressure from the aircraft. Additionally, since it was determined that predicted fuselage strains for both pressurized and unpressurized load cases remained

  17. Global Cost and Weight Evaluation of Fuselage Side Panel Design Concepts

    NASA Technical Reports Server (NTRS)

    Polland, D. R.; Finn, S. R.; Griess, K. H.; Hafenrichter, J. L.; Hanson, C. T.; Ilcewicz, L. B.; Metschan, S. L.; Scholz, D. B.; Smith, P. J.

    1997-01-01

    This report documents preliminary design trades conducted under NASA contracts NAS1 18889 (Advanced Technology Composite Aircraft Structures, ATCAS) and NAS1-19349 (Task 3, Pathfinder Shell Design) for a subsonic wide body commercial aircraft fuselage side panel section utilizing composite materials. Included in this effort were (1) development of two complete design concepts, (2) generation of cost and weight estimates, (3) identification of technical issues and potential design enhancements, and (4) selection of a single design to be further developed. The first design concept featured an open-section stringer stiffened skin configuration while the second was based on honeycomb core sandwich construction. The trade study cost and weight results were generated from comprehensive assessment of each structural component comprising the fuselage side panel section from detail fabrication through airplane final assembly. Results were obtained in three phases: (1) for the baseline designs, (2) after global optimization of the designs, and (3) the results anticipated after detailed design optimization. A critical assessment of both designs was performed to determine the risk associated with each concept, that is the relative probability of achieving the cost and weight projections. Seven critical technical issues were identified as the first step towards side panel detailed design optimization.

  18. Discrete crack growth analysis methodology for through cracks in pressurized fuselage structures

    NASA Astrophysics Data System (ADS)

    Potyondy, David O.; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1995-05-01

    A methodology for simulating the growth of long through cracks in the skin of pressurized aircraft fuselage structures is described. Crack trajectories are allowed to be arbitrary and are computed as part of the simulation. The interaction between the mechanical loads acting on the superstructure and the local structural response near the crack tips is accounted for by employing a hierarchical modelling strategy. The structural response for each cracked configuration is obtained using a geometrically non-linear shell finite element analysis procedure. Four stress intensity factors, two for membrane behavior and two for bending using Kirchhoff plate theory, are computed using an extension of the modified crack closure integral method. Crack trajectories are determined by applying the maximum tangential stress criterion. Crack growth results in localized mesh deletion, and the deletion regions are remeshed automatically using a newly developed all-quadrilateral meshing algorithm. The effectiveness of the methodology, and its applicability to performing practical analyses of realistic structures, is demonstrated by simulating curvilinear crack growth in a fuselage panel that is representative of a typical narrow-body aircraft. The predicted crack trajectory and fatigue life compare well with measurements of these same quantities from a full-scale pressurized panel test.

  19. Discrete crack growth analysis methodology for through cracks in pressurized fuselage structures

    NASA Astrophysics Data System (ADS)

    Potyondy, David O.; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1994-09-01

    A methodology for simulating the growth of long through cracks in the skin of pressurized aircraft fuselage structures is described. Crack trajectories are allowed to be arbitrary and are computed as part of the simulation. The interaction between the mechanical loads acting on the superstructure and the local structural response near the crack tips is accounted for by employing a hierarchical modeling strategy. The structural response for each cracked configuration is obtained using a geometrically nonlinear shell finite element analysis procedure. Four stress intensity factors, two for membrane behavior and two for bending using Kirchhoff plate theory, are computed using an extension of the modified crack closure integral method. Crack trajectories are determined by applying the maximum tangential stress criterion. Crack growth results in localized mesh deletion, and the deletion regions are remeshed automatically using a newly developed all-quadrilateral meshing algorithm. The effectiveness of the methodology and its applicability to performing practical analyses of realistic structures is demonstrated by simulating curvilinear crack growth in a fuselage panel that is representative of a typical narrow-body aircraft. The predicted crack trajectory and fatigue life compare well with measurements of these same quantities from a full-scale pressurized panel test.

  20. Use of nondestructive inspection and fiber optic sensing for damage characterization in carbon fiber fuselage structure

    NASA Astrophysics Data System (ADS)

    Neidigk, Stephen; Le, Jacqui; Roach, Dennis; Duvall, Randy; Rice, Tom

    2014-04-01

    To investigate a variety of nondestructive inspection technologies and assess impact damage characteristics in carbon fiber aircraft structure, the FAA Airworthiness Assurance Center, operated by Sandia National Labs, fabricated and impact tested two full-scale composite fuselage sections. The panels are representative of structure seen on advanced composite transport category aircraft and measured approximately 56"x76". The structural components consisted of a 16 ply skin, co-cured hat-section stringers, fastened shear ties and frames. The material used to fabricate the panels was T800 unidirectional pre-preg (BMS 8-276) and was processed in an autoclave. Simulated hail impact testing was conducted on the panels using a high velocity gas gun with 2.4" diameter ice balls in collaboration with the University of California San Diego (UCSD). Damage was mapped onto the surface of the panels using conventional, hand deployed ultrasonic inspection techniques, as well as more advanced ultrasonic and resonance scanning techniques. In addition to the simulated hail impact testing performed on the panels, 2" diameter steel tip impacts were used to produce representative impact damage which can occur during ground maintenance operations. The extent of impact damage ranges from less than 1 in2 to 55 in2 of interply delamination in the 16 ply skin. Substructure damage on the panels includes shear tie cracking and stringer flange disbonding. It was demonstrated that the fiber optic distributed strain sensing system is capable of detecting impact damage when bonded to the backside of the fuselage.

  1. Discrete crack growth analysis methodology for through cracks in pressurized fuselage structures

    NASA Technical Reports Server (NTRS)

    Potyondy, David O.; Wawrzynek, Paul A.; Ingraffea, Anthony R.

    1994-01-01

    A methodology for simulating the growth of long through cracks in the skin of pressurized aircraft fuselage structures is described. Crack trajectories are allowed to be arbitrary and are computed as part of the simulation. The interaction between the mechanical loads acting on the superstructure and the local structural response near the crack tips is accounted for by employing a hierarchical modeling strategy. The structural response for each cracked configuration is obtained using a geometrically nonlinear shell finite element analysis procedure. Four stress intensity factors, two for membrane behavior and two for bending using Kirchhoff plate theory, are computed using an extension of the modified crack closure integral method. Crack trajectories are determined by applying the maximum tangential stress criterion. Crack growth results in localized mesh deletion, and the deletion regions are remeshed automatically using a newly developed all-quadrilateral meshing algorithm. The effectiveness of the methodology and its applicability to performing practical analyses of realistic structures is demonstrated by simulating curvilinear crack growth in a fuselage panel that is representative of a typical narrow-body aircraft. The predicted crack trajectory and fatigue life compare well with measurements of these same quantities from a full-scale pressurized panel test.

  2. Recommendations for numerical solution of reinforced-panel and fuselage-ring problems

    NASA Technical Reports Server (NTRS)

    Hoff, N J; Libby, Paul A

    1949-01-01

    Procedures are recommended for solving the equations of equilibrium of reinforced panels and isolated fuselage rings as represented by the external loads and the operations table established according to Southwell's method. From the solution of these equations the stress distribution can be easily determined. The method of systematic relaxations, the matrix-calculus method, and several other methods applicable in special cases are discussed. Definite recommendations are made for obtaining the solution of reinforced-panel problems which are generally designated as shear lag problems. The procedures recommended are demonstrated in the analysis of a number of panels. In the case of fuselage rings it is not possible to make definite recommendations for the solution of the equilibrium equations for all rings and loadings. However, suggestions based on the latest experience are made and demonstrated on several rings.

  3. Design of a spanloader cargo aircraft

    NASA Technical Reports Server (NTRS)

    Weisshaar, Terrence A.

    1989-01-01

    The design features of an aircraft capable of fulfilling a long haul, high capacity cargo mission are described. This span-loading aircraft, or flying wing, is capable of carrying extremely large payloads and is expected to be in demand to replace the slow-moving cargo ships currently in use. The spanloader seeks to reduce empty weight by eliminating the aircraft fuselage. Disadvantages are the thickness of the cargo-containing wing, and resulting stability and control problems. The spanloader presented here has a small fuselage, low-aspect ratio wings, winglets, and uses six turbofan engines for propulsion. It will have a payload capacity of 300,000 pounds plus 30 first class passengers and 6 crew members. Its projected market is transportation of freight from Europe and the U.S.A. to countries in the Pacific Basin. Cost estimates support its economic feasibility.

  4. Unsteady transonic flow calculations for wing-fuselage configurations

    NASA Technical Reports Server (NTRS)

    Batina, J. T.

    1986-01-01

    Unsteady transonic flow calculations are presented for wing-fuselage configurations. Calculations are performed by extending the XTRAN3S unsteady transonic small-disturbance code to allow the treatment of a fuselage. Details of the XTRAN3S fuselage modeling are discussed in the context of the small-disturbance equation. Transonic calculations are presented for three wing-fuselage configurations with leading edge sweep angles ranging from 0 deg to 46.76 deg. Simple bending and torsion modal oscillations of the wing are calculated. Sectional lift and moment coefficients for the wing-alone and wing-fuselage cases are compared and the effects of fuselage aerodynamic interference on the unsteady wing loading are revealed. Tabulated generalized aerodynamic forces used in flutter analyses, indicate small changes in the real in-phase component and as much as a 30% change in the imaginary component when the fuselage is included in the calculation. These changes result in a 2 to 5% increase in total magnitude and a several degree increase in phase.

  5. Pseudomonas putida Fis Binds to the lapF Promoter In Vitro and Represses the Expression of LapF

    PubMed Central

    Lahesaare, Andrio; Moor, Hanna; Kivisaar, Maia; Teras, Riho

    2014-01-01

    The biofilm matrix of the rhizospheric bacterium Pseudomonas putida consists mainly of a proteinaceous component. The two largest P. putida proteins, adhesins LapA and LapF, are involved in biofilm development but prevail in different developmental stages of the biofilm matrix. LapA is abundant in the initial stage of biofilm formation whereas LapF is found in the mature biofilm. Although the transcriptional regulation of the adhesins is not exhaustively studied, some factors that can be involved in their regulation have been described. For example, RpoS, the major stress response sigma factor, activates, and Fis represses LapF expression. This study focused on the LapF expression control by Fis. Indeed, using DNase I footprint analysis a Fis binding site Fis-F2 was located 150 bp upstream of the lapF gene coding sequence. The mapped 5′ end of the lapF mRNA localized the promoter to the same region, overlapping with the Fis binding site Fis-F2. Monitoring the lapF promoter activity by a β-galactosidase assay revealed that Fis overexpression causes a 4-fold decrease in the transcriptional activity. Furthermore, mutations that diminished Fis binding to the Fis-F2 site abolished the repression of the lapF promoter. Thus, these data suggest that Fis is involved in the biofilm regulation via repression of LapF expression. PMID:25545773

  6. Low-speed stability and control characteristics of a transport model with aft-fuselage-mounted advanced turboprops

    NASA Technical Reports Server (NTRS)

    Applin, Z. T.; Coe, P. L., Jr.

    1986-01-01

    A limited experimental investigation was conducted in the Langley 4- by 7-Meter Tunnel to explore the effects of aft-fuselage-mounted advanced turboprop installations on the low-speed stability and control characteristics of a representative transport aircraft in a landing configuration. In general, the experimental results indicate that the longitudinal and lateral-directional stability characteristics for the aft-fuselage-mounted single-rotation tractor and counter-rotation pusher propeller configurations tested during this investigation are acceptable aerodynamically. For the single-rotation tractor configuration, the propeller-induced aerodynamics are significantly influenced by the interaction of the propeller slipstream with the pylon and nacelle. The stability characteristics for the counter-rotation pusher configuration are strongly influenced by propeller normal forces. The longitudinal and directional control effectiveness, engine-out characteristics, and ground effects are also presented. In addition, a tabulated presentation of all aerodynamic data presented in this report is included as an appendix.

  7. Aerodynamic Interaction Effects of a Helicopter Rotor and Fuselage

    NASA Technical Reports Server (NTRS)

    Boyd, David D., Jr.

    1999-01-01

    A three year Cooperative Research Agreements made in each of the three years between the Subsonic Aerodynamics Branch of the NASA Langley Research Center and the Virginia Polytechnic Institute and State University (Va. Tech) has been completed. This document presents results from this three year endeavor. The goal of creating an efficient method to compute unsteady interactional effects between a helicopter rotor and fuselage has been accomplished. This paper also includes appendices to support these findings. The topics are: 1) Rotor-Fuselage Interactions Aerodynamics: An Unsteady Rotor Model; and 2) Rotor/Fuselage Unsteady Interactional Aerodynamics: A New Computational Model.

  8. Advanced emergency openings for commercial aircraft

    NASA Technical Reports Server (NTRS)

    Bement, L. J.; Schimmel, M. L.

    1985-01-01

    Explosively actuated openings in composite panels are proposed to enhance passenger survivability within commercial aircraft by providing improvements in emergency openings, fuselage venting, and fuel dump. The concept is to embed a tiny, highly stable explosive cord in the periphery of a load-carrying composite panel; on initiation of the cord, the panel is fractured to create a well-defined opening. The panel would be installed in the sides of the fuselage for passenger egress, in the top of the fuselage for smoke venting, and in the bottoms of the fuel cells for fuel dump. Described are the concerns with the use of explosive systems, safety improvements, advantages, experimental results, and recommended approach to gain acceptance and develop this concept.

  9. An improved source model for aircraft interior noise studies

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.; Fuller, C. R.

    1985-01-01

    There is concern that advanced turboprop engines currently being developed may produce excessive aircraft cabin noise levels. This concern has stimulated renewed interest in developing aircraft interior noise reduction methods that do not significantly increase take off weight. An existing analytical model for noise transmission into aircraft cabins was utilized to investigate the behavior of an improved propeller source model for use in aircraft interior noise studies. The new source model, a virtually rotating dipole, is shown to adequately match measured fuselage sound pressure distributions, including the correct phase relationships, for published data. The virtually rotating dipole is used to study the sensitivity of synchrophasing effectiveness to the fuselage sound pressure trace velocity distribution. Results of calculations are presented which reveal the importance of correctly modeling the surface pressure phase relations in synchrophasing and other aircraft interior noise studies.

  10. Large-Scale Advanced Prop-Fan (LAP) pitch change actuator and control design report

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.; Carvalho, P.; Cutler, M. J.

    1986-01-01

    In recent years, considerable attention has been directed toward improving aircraft fuel consumption. Studies have shown that the high inherent efficiency previously demonstrated by low speed turboprop propulsion systems may now be extended to today's higher speed aircraft if advanced high-speed propeller blades having thin airfoils and aerodynamic sweep are utilized. Hamilton Standard has designed a 9-foot diameter single-rotation Large-Scale Advanced Prop-Fan (LAP) which will be tested on a static test stand, in a high speed wind tunnel and on a research aircraft. The major objective of this testing is to establish the structural integrity of large-scale Prop-Fans of advanced construction in addition to the evaluation of aerodynamic performance and aeroacoustic design. This report describes the operation, design features and actual hardware of the (LAP) Prop-Fan pitch control system. The pitch control system which controls blade angle and propeller speed consists of two separate assemblies. The first is the control unit which provides the hydraulic supply, speed governing and feather function for the system. The second unit is the hydro-mechanical pitch change actuator which directly changes blade angle (pitch) as scheduled by the control.

  11. Homologs of the LapD-LapG c-di-GMP Effector System Control Biofilm Formation by Bordetella bronchiseptica

    PubMed Central

    Ambrosis, Nicolás; Boyd, Chelsea D.; O´Toole, George A.; Fernández, Julieta; Sisti, Federico

    2016-01-01

    Biofilm formation is important for infection by many pathogens. Bordetella bronchiseptica causes respiratory tract infections in mammals and forms biofilm structures in nasal epithelium of infected mice. We previously demonstrated that cyclic di-GMP is involved in biofilm formation in B. bronchiseptica. In the present work, based on their previously reported function in Pseudomonas fluorescens, we identified three genes in the B. bronchiseptica genome likely involved in c-di-GMP-dependent biofilm formation: brtA, lapD and lapG. Genetic analysis confirmed a role for BrtA, LapD and LapG in biofilm formation using microtiter plate assays, as well as scanning electron and fluorescent microscopy to analyze the phenotypes of mutants lacking these proteins. In vitro and in vivo studies showed that the protease LapG of B. bronchiseptica cleaves the N-terminal domain of BrtA, as well as the LapA protein of P. fluorescens, indicating functional conservation between these species. Furthermore, while BrtA and LapG appear to have little or no impact on colonization in a mouse model of infection, a B. bronchiseptica strain lacking the LapG protease has a significantly higher rate of inducing a severe disease outcome compared to the wild type. These findings support a role for c-di-GMP acting through BrtA/LapD/LapG to modulate biofilm formation, as well as impact pathogenesis, by B. bronchiseptica PMID:27380521

  12. A study on the diamond lapping direction determination

    NASA Astrophysics Data System (ADS)

    Yang, Ning; Zong, WenJun; Li, ZengQiang; Sun, Tao

    2014-08-01

    The anisotropy of material removal rate for diamond gives a method to control the lapping rate of diamond specimen, i.e. changing the lapping direction. This requires comprehension on the relationship of the material removal rate and the lapping direction for diamond. This paper provides a method to figure out the diamond lapping direction. By preprocessing a straight edge formed by lapping a surface intersects with the required machining surface, the diamond lapping direction can be figured out under the Confocal Scanning Laser Microscope only if the crystal directions of the two surfaces are determined at first. The advantage of our method is that there is no need to consider the position and posture of the diamond specimen fixed on the holder.

  13. Dogs lap using acceleration-driven open pumping

    PubMed Central

    Gart, Sean; Socha, John J.; Vlachos, Pavlos P.; Jung, Sunghwan

    2015-01-01

    Dogs lap because they have incomplete cheeks and cannot suck. When lapping, a dog’s tongue pulls a liquid column from the bath, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured lapping in 19 dogs and used the results to generate a physical model of the tongue’s interaction with the air–fluid interface. These experiments help to explain how dogs exploit the fluid dynamics of the generated column. The results demonstrate that effects of acceleration govern lapping frequency, which suggests that dogs curl the tongue to create a larger liquid column. Comparing lapping in dogs and cats reveals that, despite similar morphology, these carnivores lap in different physical regimes: an unsteady inertial regime for dogs and steady inertial regime for cats. PMID:26668382

  14. Systematic Construction of Real Lapped Tight Frame Transforms

    PubMed Central

    Sandryhaila, Aliaksei; Chebira, Amina; Milo, Christina; Kovčcević, Jelena; Püschel, Markus

    2010-01-01

    We present a constructive algorithm for the design of real lapped equal-norm tight frame transforms. These transforms can be efficiently implemented through filter banks and have recently been proposed as a redundant counterpart to lapped orthogonal transforms, as well as an infinite-dimensional counterpart to harmonic tight frames. The proposed construction consists of two parts: First, we design a large class of new real lapped orthogonal transforms derived from submatrices of the discrete Fourier transform. Then, we seed these to obtain real lapped tight frame transforms corresponding to tight, equal-norm frames. We identify those frames that are maximally robust to erasures, and show that our construction leads to a large class of new lapped orthogonal transforms as well as new lapped tight frame transforms. PMID:20607116

  15. Dogs lap using acceleration-driven open pumping.

    PubMed

    Gart, Sean; Socha, John J; Vlachos, Pavlos P; Jung, Sunghwan

    2015-12-29

    Dogs lap because they have incomplete cheeks and cannot suck. When lapping, a dog's tongue pulls a liquid column from the bath, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured lapping in 19 dogs and used the results to generate a physical model of the tongue's interaction with the air-fluid interface. These experiments help to explain how dogs exploit the fluid dynamics of the generated column. The results demonstrate that effects of acceleration govern lapping frequency, which suggests that dogs curl the tongue to create a larger liquid column. Comparing lapping in dogs and cats reveals that, despite similar morphology, these carnivores lap in different physical regimes: an unsteady inertial regime for dogs and steady inertial regime for cats. PMID:26668382

  16. Analysis and Testing of a Composite Fuselage Shield for Open Rotor Engine Blade-Out Protection

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Emmerling, William; Seng, Silvia; Frankenberger, Charles; Ruggeri, Charles R.; Revilock, Duane M.; Carney, Kelly S.

    2015-01-01

    The Federal Aviation Administration is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the Aircraft. The NASA Glenn Research Center and The Naval Air Warfare Center (NAWC), China Lake, collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test lightweight composite shields for protection of the aircraft passengers and critical systems from a released blade that could impact the fuselage. In the test, two composite blades were pyrotechnically released from a running engine, each impacting a composite shield with a different thickness. The thinner shield was penetrated by the blade and the thicker shield prevented penetration. This was consistent with pre-test predictions. This paper documents the live fire test from the full scale rig at NAWC China Lake and describes the damage to the shields as well as instrumentation results.

  17. Crack curving in a ductile pressurized fuselage

    NASA Astrophysics Data System (ADS)

    Lam, Paul W.

    Moire interferometry was used to study crack tip displacement fields of a biaxially loaded cruciform type 0.8mm thick 2024-T3 aluminum specimen with various tearstrap reinforcement configurations: Unreinforced, Bonded, Bonded+Riveted, and Machined Pad-up. A program was developed using the commercially available code Matlab to derive strain, stress, and integral parameters from the experimental displacements. An FEM model of the crack tip area, with experimental displacements as boundary conditions, was used to validate FEM calculations of crack tip parameters. The results indicate that T*-integral parameter reaches a value of approximately 120 MPa-m0.5 during stable crack propagation which agrees with previously published values for straight cracks in the same material. The approximate computation method employed in this study uses a partial contour around the crack tip that neglects the contribution from the portion behind the crack tip where there is significant unloading. Strain distributions around the crack tip were obtained from experimental displacements and indicate that Maximum Principal Strain or Equivalent Strain can predict the direction of crack propagation, and is generally comparable with predictions using the Erdogan-Sih and Kosai-Ramulu-Kobayashi criteria. The biaxial tests to failure showed that the Machined Pad-up specimen carried the highest load, with the Bonded specimen next, at 78% of the Machined Pad-up value. The Bonded+Riveted specimen carried a lower load than the Bonded, at 67% of the Machined Pad-up value, which was the same as that carried by the Unreinforced specimen. The tearstraps of the bonded specimens remained intact after the specimen failed while the integrally machined reinforcement broke with the specimen. FEM studies were also made of skin flapping in typical Narrow and Wide-body fuselage sections, both containing the same crack path from a full-scale fatigue test of a Narrow-body fuselage. Results indicate that the

  18. Rotor-Fuselage Interaction: Analysis and Validation with Experiment

    NASA Technical Reports Server (NTRS)

    Berry, John D.; Bettschart, Nicolas

    1997-01-01

    The problem of rotor-fuselage aerodynamic interaction has to be considered in industry applications from various aspects. First, in order to increase helicopter speed and reduce operational costs, rotorcraft tend to be more and more compact, with a main rotor closer to the fuselage surface. This creates significant perturbations both on the main rotor and on the fuselage, including steady and unsteady effects due to blade and wake passage and perturbed inflow at the rotor disk. Furthermore,the main rotor wake affects the tail boom, empennage and anti-torque system. This has important consequences for helicopter control and vibrations at low speeds and also on tail rotor acoustics (main rotor wake-tail rotor interactions). This report describes the US Army-France MOD cooperative work on this problem from both the theoretical and experimental aspects. Using experimental 3D velocity field and fuselage surface pressure measurements, three codes that model the interactions of a helicopter rotor with a fuselage are compared. These comparisons demonstrate some of the strengths and weaknesses of current models for the combined rotor-fuselage analysis.

  19. New design deforming controlling system of the active stressed lap

    NASA Astrophysics Data System (ADS)

    Ying, Li; Wang, Daxing

    2008-07-01

    A 450mm diameter active stressed lap has been developed in NIAOT by 2003. We design a new lap in 2007. This paper puts on emphases on introducing the new deforming control system of the lap. Aiming at the control characteristic of the lap, a new kind of digital deforming controller is designed. The controller consists of 3 parts: computer signal disposing, motor driving and force sensor signal disposing. Intelligent numeral PID method is applied in the controller instead of traditional PID. In the end, the result of new deformation are given.

  20. Interior noise control ground test studies for advanced turboprop aircraft applications

    NASA Technical Reports Server (NTRS)

    Simpson, Myles A.; Cannon, Mark R.; Burge, Paul L.; Boyd, Robert P.

    1989-01-01

    The measurement and analysis procedures are documented, and the results of interior noise control ground tests conducted on a DC-9 aircraft test section are summarized. The objectives of these tests were to study the fuselage response characteristics of treated and untreated aircraft with aft-mount advanced turboprop engines and to analyze the effectiveness of selected noise control treatments in reducing passenger cabin noise on these aircraft. The results of fuselage structural mode surveys, cabin cavity surveys and sound intensity surveys are presented. The performance of various structural and cabin sidewall treatments is assessed, based on measurements of the resulting interior noise levels under simulated advanced turboprop excitation.

  1. A study of the structural-acoustic response and interior noise levels of fuselage structures

    NASA Technical Reports Server (NTRS)

    Koval, L. R.

    1978-01-01

    Models of both flat and curved fuselage panels were tested for their sound transmission characteristics. The effect of external air flow on transmission loss was simulated in a subsonic wind-tunnel. By numerically evaluating the known equations for field-incidence transmission loss of single-walled panels in a computer program, a comparison of the theory with the test results was made. As a further extension to aircraft fuselage simulation, equations for the field-incidence transmission loss of a double-walled panel were derived. Flow is shown to provide a small increase in transmission loss for a flat panel. Curvature is shown to increase transmission loss for low frequencies, while also providing a sharp decrease in transmission loss at the ring frequency of the cylindrical panel. The field-incidence transmission loss of a double-walled panel was found to be approximately twice that for a single-walled panel, with the addition of dips in the transmission loss at the air gap resonances and at the critical frequency of the internal panel.

  2. Mechanisms of transmission and control of low-frequency sound in aircraft interiors

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1985-01-01

    A simplified analytical model is used to study the principal mechanisms at work in propeller noise source radiation, fuselage response, and the behavior of the coupled inner acoustic field, in order to control low frequency sound in aircraft interiors. Both active and passive methods of noise control are comparatively evaluated in light of the transmission mechanisms. Fuselage vibrational response is noted to be dominated by only a few lower order circumferential modes.

  3. Diamond machine tool face lapping machine

    DOEpatents

    Yetter, H.H.

    1985-05-06

    An apparatus for shaping, sharpening and polishing diamond-tipped single-point machine tools. The isolation of a rotating grinding wheel from its driving apparatus using an air bearing and causing the tool to be shaped, polished or sharpened to be moved across the surface of the grinding wheel so that it does not remain at one radius for more than a single rotation of the grinding wheel has been found to readily result in machine tools of a quality which can only be obtained by the most tedious and costly processing procedures, and previously unattainable by simple lapping techniques.

  4. Bending behavior of lapped plastic ehv cables

    SciTech Connect

    Morgan, G H; Muller, A C

    1980-01-01

    One of the factors delaying the development of lapped polymeric cables has been their reputed poor bending characteristics. Complementary programs were begun at BNL several years ago to mathematically model the bending of synthetic tape cables and to develop novel plastic tapes designed to have moduli more favorable to bending. A series of bend tests was recently completed to evaluate the bending performance of several tapes developed for use in experimental superconducting cables. The program is discussed and the results of the bend tests are summarized.

  5. Analysis of adhesively bonded composite lap joints

    SciTech Connect

    Tong, L.; Kuruppu, M.; Kelly, D.

    1994-12-31

    A new nonlinear formulation is developed for the governing equations for the shear and peel stresses in adhesively bonded composite double lap joints. The new formulation allows arbitrary nonlinear stress-strain characteristics in both shear and peel behavior. The equations are numerically integrated using a shooting technique and Newton-Raphson method behind a user friendly interface. The failure loads are predicted by utilizing the maximum stress criterion, interlaminar delamination and the energy density failure criteria. Numerical examples are presented to demonstrate the effect of the nonlinear adhesive behavior on the stress distribution and predict the failure load and the associated mode.

  6. Modulated lapped transforms in image coding

    NASA Astrophysics Data System (ADS)

    de Queiroz, Ricardo L.; Rao, K. R.

    1994-05-01

    The class of modulated lapped transforms (MLT) with extended overlap is investigated in image coding. The finite-length-signals implementation using symmetric extensions is introduced and human visual sensitivity arrays are computed. Theoretical comparisons with other popular transforms are carried and simulations are made using intraframe coders. Emphasis is given in transmission over packet networks assuming high rate of data losses. The MLT with overlap factor 2 is shown to be superior in all our tests with bonus features such as greater robustness against block losses.

  7. Analysis of aircraft wing-mounted antenna patterns

    NASA Technical Reports Server (NTRS)

    Marhefka, R. J.

    1976-01-01

    High frequency radiation patterns of aircraft wing mounted antennas are analyzed. Basic antenna types using ray optical techniques are studied. The aircraft is modelled in its most basic form so that this study is applicable to general type aircraft. The fuselage is modelled as a perfectly conducting finite elliptic cylinder. The wings and horizontal and vertical stabilizers are modelled as perfectly conducting "n" sided flat plates that can be arbitrarily attached to the fuselage or to themselves. The antenna locations are assumed to be on the surfaces of the wings at locations removed from engines and stores such that these effects are negligible. Volumetric patterns are calculated for several aircraft. The validity of the solution is shown by comparing the results against scale model measurements. The application of this solution to practical airborne antenna problems has shown its versatility in designing antennas and predicting their radiation patterns in an accurate and efficient manner.

  8. Advanced methods of structural and trajectory analysis for transport aircraft

    NASA Technical Reports Server (NTRS)

    Ardema, Mark D.

    1995-01-01

    This report summarizes the efforts in two areas: (1) development of advanced methods of structural weight estimation, and (2) development of advanced methods of trajectory optimization. The majority of the effort was spent in the structural weight area. A draft of 'Analytical Fuselage and Wing Weight Estimation of Transport Aircraft', resulting from this research, is included as an appendix.

  9. Three-dimensional boundary layer calculations on wings, starting from the fuselage

    NASA Astrophysics Data System (ADS)

    Lindhout, J. P. F.; Deboer, E.; Vandenberg, B.

    1982-12-01

    A computational method for three dimensional turbulent boundary layers is presented. The turbulence model is a simple eddy viscosity formulation. A hybrid difference scheme which has the robustness of first order schemes and accuracy of second order schemes is used. The boundary layer is computed in the region of determinacy of the initial data. No extra data has to be given along the lateral boundaries of the computational domain. Results of the boundary layer flow over the fuselage of an aircraft-like body are presented. The computation follows the strongly three dimensional flow over the leading edge of the fairing and wing, after the boundary layer on wing upper and lower surface is computed.

  10. Isolation and Characterization of the Neutral Leucine Aminopeptidase (LapN) of Tomato1

    PubMed Central

    Tu, Chao-Jung; Park, Sang-Youl; Walling, Linda L.

    2003-01-01

    Tomatoes (Lycopersicon esculentum) express two forms of leucine aminopeptidase (LAP-A and LAP-N) and two LAP-like proteins. The relatedness of LAP-N and LAP-A was determined using affinity-purified antibodies to four LAP-A protein domains. Antibodies to epitopes in the most N-terminal region were able to discriminate between LAP-A and LAP-N, whereas antibodies recognizing central and COOH-terminal regions recognized both LAP polypeptides. Two-dimensional immunoblots showed that LAP-N and the LAP-like proteins were detected in all vegetative (leaves, stems, roots, and cotyledons) and reproductive (pistils, sepals, petals, stamens, and floral buds) organs examined, whereas LAP-A exhibited a distinct expression program. LapN was a single-copy gene encoding a rare-class transcript. A full-length LapN cDNA clone was isolated, and the deduced sequence had 77% peptide sequence identity with the wound-induced LAP-A. Comparison of LAP-N with other plant LAPs identified 28 signature residues that classified LAP proteins as LAP-N or LAP-A like. Overexpression of a His6-LAP-N fusion protein in Escherichia coli demonstrated distinct differences in His6-LAP-N and His6-LAP-A activities. Similar to LapA, the LapN RNA encoded a precursor protein with a molecular mass of 60 kD. The 5-kD presequence had features similar to plastid transit peptides, and processing of the LAP-N presequence could generate the mature 55-kD LAP-N. Unlike LapA, the LapN transcript contained a second in-frame ATG, and utilization of this potential initiation codon would yield a 55-kD LAP-N protein. The localization of LAP-N could be controlled by the balance of translational initiation site utilization and LAP-N preprotein processing. PMID:12746529

  11. How dogs lap: open pumping driven by acceleration

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Socha, John; Vlachos, Pavlos; Jung, Sunghwan

    2015-11-01

    Dogs drink by lapping because they have incomplete cheeks and cannot suck fluids into the mouth. When lapping, a dog's tongue pulls a liquid column from a bath, which is then swallowed, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured the kinematics of lapping from nineteen dogs and used the results to generate a physical model of the tongue's interaction with the air-fluid interface. These experiments with an accelerating rod help to explain how dogs exploit the fluid dynamics of the generated column. The results suggest that effects of acceleration govern lapping frequency, and that dogs curl the tongue ventrally (backwards) and time their bite on the column to increase fluid intake per lap. Comparing lapping in dogs and cats reveals that though they both lap with the same frequency scaling with respect to body mass and have similar morphology, these carnivores lap in different physical regimes: a high-acceleration regime for dogs and a low-acceleration regime for cats.

  12. Learning Activity Package, Chemistry I, (LAP) Study 29.

    ERIC Educational Resources Information Center

    Jones, Naomi

    Presented is a Learning Activity Package (LAP) study concerned with carbon and its compounds. This LAP in chemistry includes a rationale for studying the chemical element of carbon, a list of student objectives (stated in behavioral terms), of activities (reading, laboratory experiments, model construction, etc.), a two-page worksheet, a…

  13. Design Document: KWIC Module; L.A.P. Version I.

    ERIC Educational Resources Information Center

    Porch, Ann

    The Language Analysis Package (LAP) was developed by the Southwest Regional Laboratory (SWRL) to assist researchers in the analysis of language usage. The function of the KWIC (Keyword-in Context or Concordance) Module of the LAP is to produce keyword listings from the input text being analyzed. Such listings will contain location information…

  14. Free wing assembly for an aircraft

    NASA Technical Reports Server (NTRS)

    Wolowicz, C. H. (Inventor)

    1978-01-01

    A free wing is attached to a fuselage of an aircraft in a manner such that the wing is free to pivot about a spanwise axis forward of its aerodynamic center. The wing is angularly displaced about the axis by aerodynamic pitching moments, resulting from lift, and is trimmed through a use of a trimmable free stabilizer comprising a floating canard mounted on a strut rigidly connected to the wing and projected forward from it.

  15. On a global aerodynamic optimization of a civil transport aircraft

    NASA Technical Reports Server (NTRS)

    Savu, G.; Trifu, O.

    1991-01-01

    An aerodynamic optimization procedure developed to minimize the drag to lift ratio of an aircraft configuration: wing - body - tail, in accordance with engineering restrictions, is described. An algorithm developed to search a hypersurface with 18 dimensions, which define an aircraft configuration, is discussed. The results, when considered from the aerodynamic point of view, indicate the optimal configuration is one that combines a lifting fuselage with a canard.

  16. Experimental study on lapping of micro groove with controlled force

    NASA Astrophysics Data System (ADS)

    Ding, Fei; Wang, Bo; Li, Guo; Che, Lin; Mao, Xing

    2014-08-01

    Precision parts with complicated microstructures have been in increasing demand in the field of inertial navigation systems and structured molds. Micro milling is a direct operation to manufacture the micro structure but it will induce unexpected tool marks and deterioration layer. A novel lapping method based on controlled force is proposed as the final finishing process. The method offers efficient position determination strategy for the structure and is capable to monitor the lapping condition. In the paper, processing method and the developed lapping apparatus was firstly introduced. Then, the individual influence on finished surface of several processing parameters including abrasive size, amount of feed and lapping trajectory are investigated. Results show that the deterioration layer was successfully removed with different slurries without diminution of its original form accuracy. Lapping efficiency is also taken into account in the choosing of parameters. The formative mechanism of parallel scratches observed in experiments is analyzed and verified.

  17. The cetaceopteryx: A global range military transport aircraft

    NASA Technical Reports Server (NTRS)

    Brivkalns, Chad; English, Nicole; Kazemi, Tahmineh; Kopel, Kim; Kroger, Seth; Ortega, ED

    1993-01-01

    This paper presents a design of a military transport aircraft capable of carrying 800,000 lbs of payload from any point in the United States to any other point in the world. Such massive airlift requires aggressive use of advanced technology and a unique configuration. The Cetaceopteyx features a joined wing, canard and six turbofan engines. The aircraft has a cost 1.07 billion (1993) dollars each. This paper presents in detail the mission description, preliminary sizing, aircraft configuration, wing design, fuselage design, empennage design, propulsion system, landing gear design, structures, drag, stability and control, systems layout, and cost analysis of the aircraft.

  18. Monte Carlo simulation methodology for the reliabilty of aircraft structures under damage tolerance considerations

    NASA Astrophysics Data System (ADS)

    Rambalakos, Andreas

    Current federal aviation regulations in the United States and around the world mandate the need for aircraft structures to meet damage tolerance requirements through out the service life. These requirements imply that the damaged aircraft structure must maintain adequate residual strength in order to sustain its integrity that is accomplished by a continuous inspection program. The multifold objective of this research is to develop a methodology based on a direct Monte Carlo simulation process and to assess the reliability of aircraft structures. Initially, the structure is modeled as a parallel system with active redundancy comprised of elements with uncorrelated (statistically independent) strengths and subjected to an equal load distribution. Closed form expressions for the system capacity cumulative distribution function (CDF) are developed by expanding the current expression for the capacity CDF of a parallel system comprised by three elements to a parallel system comprised with up to six elements. These newly developed expressions will be used to check the accuracy of the implementation of a Monte Carlo simulation algorithm to determine the probability of failure of a parallel system comprised of an arbitrary number of statistically independent elements. The second objective of this work is to compute the probability of failure of a fuselage skin lap joint under static load conditions through a Monte Carlo simulation scheme by utilizing the residual strength of the fasteners subjected to various initial load distributions and then subjected to a new unequal load distribution resulting from subsequent fastener sequential failures. The final and main objective of this thesis is to present a methodology for computing the resulting gradual deterioration of the reliability of an aircraft structural component by employing a direct Monte Carlo simulation approach. The uncertainties associated with the time to crack initiation, the probability of crack detection, the

  19. High-transonic-speed transport aircraft study

    NASA Technical Reports Server (NTRS)

    Kulfan, R. M.

    1974-01-01

    An initial design study of high-transonic-speed transport aircraft has been completed. Five different design concepts were developed. These included fixed swept wing, variable-sweep wing, delta wing, double-fuselage yawed-wing, and single-fuselage yawed-wing aircraft. The boomless supersonic design objectives of range = 5560 km (3000 nmi), payload = 18,143 kg (40,000 lb), Mach = 1.2, and FAR Part 36 aircraft noise levels were achieved by the single-fuselage yawed-wing configuration with a gross weight of 211,828 kg (467,000 lb). A noise level of 15 EPNdB below FAR Part 36 requirements was obtained with a gross weight increase to 226,796 kg (500,000 lb). The off-design subsonic range capability for this configuration exceeded the Mach 1.2 design range by more than 20%. Although wing aeroelastic divergence was a primary design consideration for the yawed-wing concepts, the graphite-epoxy wings of this study were designed by critical gust and maneuver loads rather than by divergence requirements. The transonic nacelle drag is shown to be very sensitive to the nacelle installation. A six-degree-of-freedom dynamic stability analysis indicated that the control coordination and stability augmentation system would require more development than for a symmetrical airplane but is entirely feasible. A three-plane development plan is recommended to establish the full potential of the yawed-wing concept.

  20. Surface grid generation for wing-fuselage bodies

    NASA Technical Reports Server (NTRS)

    Smith, R. E.; Kudlinski, R. A.; Pitts, J. I.

    1984-01-01

    In the application of finite-difference methods to obtain numerical solutions of viscous compressible fluid flow about wing-fuselage bodies, it is advantageous to transform the governing equations to an idealized boundary-fitted coordinate system. The advantages are reduced computational complexity and added accuracy in the application of boundary conditions. The solution process requires that a grid be superimposed on the physical solution domain which corresponds to a uniform grid on a rectangular computational domain (uniform rectangular parallel-epiped). Grid generation is the determination of a one to one relationship between grid points in the physical domain and grid points in the computational domain. A technique for computing wing-fuselage surface grids using the Harris geometry and software for smooth-surface representation is described. Grid spacing control concepts which govern the relationship between the wing-fuselage surface and the computational grid are also presented.

  1. Taxiing, Take-Off, and Landing Simulation of the High Speed Civil Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Reaves, Mercedes C.; Horta, Lucas G.

    1999-01-01

    The aircraft industry jointly with NASA is studying enabling technologies for higher speed, longer range aircraft configurations. Higher speeds, higher temperatures, and aerodynamics are driving these newer aircraft configurations towards long, slender, flexible fuselages. Aircraft response during ground operations, although often overlooked, is a concern due to the increased fuselage flexibility. This paper discusses modeling and simulation of the High Speed Civil Transport aircraft during taxiing, take-off, and landing. Finite element models of the airframe for various configurations are used and combined with nonlinear landing gear models to provide a simulation tool to study responses to different ground input conditions. A commercial computer simulation program is used to numerically integrate the equations of motion and to compute estimates of the responses using an existing runway profile. Results show aircraft responses exceeding safe acceptable human response levels.

  2. Identification of a Novel Human LAP1 Isoform That Is Regulated by Protein Phosphorylation

    PubMed Central

    Santos, Mariana; Domingues, Sara C.; Costa, Patrícia; Muller, Thorsten; Galozzi, Sara; Marcus, Katrin; da Cruz e Silva, Edgar F.; da Cruz e Silva, Odete A.; Rebelo, Sandra

    2014-01-01

    Lamina associated polypeptide 1 (LAP1) is an integral protein of the inner nuclear membrane that is ubiquitously expressed. LAP1 binds to lamins and chromatin, probably contributing to the maintenance of the nuclear envelope architecture. Moreover, LAP1 also interacts with torsinA and emerin, proteins involved in DYT1 dystonia and X-linked Emery-Dreifuss muscular dystrophy disorder, respectively. Given its relevance to human pathological conditions, it is important to better understand the functional diversity of LAP1 proteins. In rat, the LAP1 gene (TOR1AIP1) undergoes alternative splicing to originate three LAP1 isoforms (LAP1A, B and C). However, it remains unclear if the same occurs with the human TOR1AIP1 gene, since only the LAP1B isoform had thus far been identified in human cells. In silico analysis suggested that, across different species, potential new LAP1 isoforms could be generated by alternative splicing. Using shRNA to induce LAP1 knockdown and HPLC-mass spectrometry analysis the presence of two isoforms in human cells was described and validated: LAP1B and LAP1C; the latter is putatively N-terminal truncated. LAP1B and LAP1C expression profiles appear to be dependent on the specific tissues analyzed and in cultured cells LAP1C was the major isoform detected. Moreover, LAP1B and LAP1C expression increased during neuronal maturation, suggesting that LAP1 is relevant in this process. Both isoforms were found to be post-translationally modified by phosphorylation and methionine oxidation and two LAP1B/LAP1C residues were shown to be dephosphorylated by PP1. This study permitted the identification of the novel human LAP1C isoform and partially unraveled the molecular basis of LAP1 regulation. PMID:25461922

  3. Axial crack propagation and arrest in pressurized fuselage

    NASA Technical Reports Server (NTRS)

    Kosai, M.; Shimamoto, A.; Yu, C.-T.; Walker, S. I.; Kobayashi, A. S.; Tan, P.

    1994-01-01

    The crack arrest capability of a tear strap in a pressurized precracked fuselage was studied through instrumented axial rupture tests of small scale models of an idealized fuselage. Upon pressurization, rapid crack propagation initiated at an axial through crack along the stringer and immediately kinked due to the mixed modes 1 and 2 state caused by the one-sided opening of the crack flap. The diagonally running crack further turned at the tear straps. Dynamic finite element analysis of the rupturing cylinder showed that the crack kinked and also ran straight in the presence of a mixed mode state according to a modified two-parameter crack kinking criterion.

  4. Experimental investigation of the crashworthiness of scaled composite sailplane fuselages

    NASA Technical Reports Server (NTRS)

    Kampf, Karl-Peter; Crawley, Edward F.; Hansman, R. John, Jr.

    1989-01-01

    The crash dynamics and energy absorption of composite sailplane fuselage segments undergoing nose-down impact were investigated. More than 10 quarter-scale structurally similar test articles, typical of high-performance sailplane designs, were tested. Fuselages segments were fabricated of combinations of fiberglass, graphite, Kevlar, and Spectra fabric materials. Quasistatic and dynamic tests were conducted. The quasistatic tests were found to replicate the strain history and failure modes observed in the dynamic tests. Failure modes of the quarter-scale model were qualitatively compared with full-scale crash evidence and quantitatively compared with current design criteria. By combining material and structural improvements, substantial increases in crashworthiness were demonstrated.

  5. Detail view of the port side of the aft fuselage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of the port side of the aft fuselage of the Orbiter Discovery in the transfer aisle of the Vehicle Assembly Building at Kennedy Space Center with a lifting frame attached to the aft attach points of the orbiter. In this view, the Orbiter Maneuvering/Reaction Control Systems pod is in place. Also note the darker-colored trapezoidal aft fuselage access door and the T-0 umbilical panel to its right in the view. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  6. Closeup oblique view of the aft fuselage of the Orbiter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and starboard with the Space Shuttle Main Engines (SSME) and Orbiter Maneuvering System/Reaction Control System pods removed. The openings for the SSMEs have been covered with a flexible barrier to create a positive pressure envelope inside of the aft fuselage. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  7. Detail view of the starboard side of the aft fuselage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of the starboard side of the aft fuselage of the Orbiter Discovery in the Orbiter Processing Facility at Kennedy Space Center with the Orbiter Maneuvering/Reaction Control Systems Pod removed and exposing the insulating foil used to protect the orbiter structure from the heat generated by the maneuvering and reaction control engines. Also note in the view that the aft fuselage access door has bee removed and also note the ground support equipment attached to the T-0 umbilical plate in the lower left of the view. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  8. Closeup oblique view of the aft fuselage of the Orbiter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and port with the Space Shuttle Main Engines (SSME) and Orbiter Maneuvering System/Reaction Control System pods still in place. However. the heat shields have been removed from the SSMEs providing a good view toward the interior of the aft fuselage. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  9. Closeup oblique view of the aft fuselage of the Orbiter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and starboard with the Space Shuttle Main Engines (SSME) and Orbiter Maneuvering System/Reaction Control System pods still in place. However. the heat shields have been removed from the SSMEs providing a good view toward the interior of the aft fuselage. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  10. The Influences of Lamination Angles on the Interior Noise Levels of an Aircraft

    NASA Technical Reports Server (NTRS)

    Fernholz, Christian M.; Robinson, Jay H.

    1996-01-01

    The feasibility of reducing the interior noise levels of an aircraft passenger cabin through optimization of the composite lay up of the fuselage is investigated. MSC/NASTRAN, a commercially available finite element code, is used to perform the dynamic analysis and subsequent optimization of the fuselage. The numerical calculation of sensitivity of acoustic pressure to lamination angle is verified using a simple thin, cylindrical shell with point force excitations as noise sources. The thin shell used represents a geometry similar to the fuselage and analytic solutions are available for the cylindrical thin shell equations of motion. Optimization of lamination angle for the reduction of interior noise is performed using a finite element model of an actual aircraft fuselage. The aircraft modeled for this study is the Beech Starship. Point forces simulate the structure borne noise produced by the engines and are applied to the fuselage at the wing mounting locations. These forces are the noise source for the optimization problem. The acoustic pressure response is reduced at a number of points in the fuselage and over a number of frequencies. The objective function is minimized with the constraint that it be larger than the maximum sound pressure level at the response points in the passenger cabin for all excitation frequencies in the range of interest. Results from the study of the fuselage model indicate that a reduction in interior noise levels is possible over a finite frequency range through optimal configuration of the lamination angles in the fuselage. Noise reductions of roughly 4 dB were attained. For frequencies outside the optimization range, the acoustic pressure response may increase after optimization. The effects of changing lamination angle on the overall structural integrity of the airframe are not considered in this study.

  11. Aircraft control system

    NASA Technical Reports Server (NTRS)

    Lisoski, Derek L. (Inventor); Kendall, Greg T. (Inventor)

    2007-01-01

    A solar rechargeable, long-duration, span-loaded flying wing, having no fuselage or rudder. Having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing's top surface, the aircraft uses only differential thrust of its eight propellers to turn, pitch and yaw. The wing is configured to deform under flight loads to position the propellers such that the control can be achieved. Each of five segments of the wing has one or more motors and photovoltaic arrays, and produces its own lift independent of the other segments, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface.

  12. Tubular lap joints for wind turbine applications

    SciTech Connect

    Reedy, E.D. Jr.; Guess, T.R.

    1990-01-01

    A combined analytical/experimental study of the strength of thick- walled, adhesively bonded PMMA-to-aluminum and E-glass/epoxy composite-to-aluminum tubular lap joints under axial load has been conducted. Test results include strength and failure mode data. Moreover, strain gages placed along the length of the outer tubular adherend characterize load transfer from one adherend to the other. The strain gage data indicate that load transfer is nonuniform and that the relatively compliant PMMA has the shorter load transfer length. Strains determined by a finite element analysis of the tested joints are in excellent agreement with those measured. Calculated bond stresses are highest in the region of observed failure, and extensive bond yielding is predicted in the E- glass/epoxy composite-to-aluminum joint prior to joint failure. 4 refs., 13 figs., 1 tab.

  13. Flaw Tolerance In Lap Shear Brazed Joints. Part 2

    NASA Technical Reports Server (NTRS)

    Wang, Len; Flom, Yury

    2003-01-01

    This paper presents results of the second part of an on-going effort to gain better understanding of defect tolerance in braze joints. In the first part of this three-part series, we mechanically tested and modeled the strength of the lap joints as a function of the overlap distance. A failure criterion was established based on the zone damage theory, which predicts the dependence of the lap joint shear strength on the overlap distance, based on the critical size of a finite damage zone or an overloaded region in the joint. In this second part of the study, we experimentally verified the applicability of the damage zone criterion on prediction of the shear strength of the lap joint and introduced controlled flaws into the lap joints. The purpose of the study was to evaluate the lap joint strength as a function of flaw size and its location through mechanical testing and nonlinear finite element analysis (FEA) employing damage zone criterion for definition of failure. The results obtained from the second part of the investigation confirmed that the failure of the ductile lap shear brazed joints occurs when the damage zone reaches approximately 10% of the overlap width. The same failure criterion was applicable to the lap joints containing flaws.

  14. 14 CFR 27.549 - Fuselage, landing gear, and rotor pylon structures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuselage, landing gear, and rotor pylon... Requirements § 27.549 Fuselage, landing gear, and rotor pylon structures. (a) Each fuselage, landing gear, and... accelerated flight and landing conditions, including engine torque. (Secs. 604, 605, 72 Stat. 778, 49...

  15. 14 CFR 27.549 - Fuselage, landing gear, and rotor pylon structures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuselage, landing gear, and rotor pylon... Requirements § 27.549 Fuselage, landing gear, and rotor pylon structures. (a) Each fuselage, landing gear, and... accelerated flight and landing conditions, including engine torque. (Secs. 604, 605, 72 Stat. 778, 49...

  16. Numerical Investigation of Rotorcraft Fuselage Drag Reduction Using Active Flow Control

    NASA Technical Reports Server (NTRS)

    Allan, Brian G.; Schaeffler, Norman W.

    2011-01-01

    The effectiveness of unsteady zero-net-mass-flux jets for fuselage drag reduction was evaluated numerically on a generic rotorcraft fuselage in forward flight with a rotor. Previous efforts have shown significant fuselage drag reduction using flow control for an isolated fuselage by experiment and numerical simulation. This work will evaluate a flow control strategy, that was originally developed on an isolated fuselage, in a more relevant environment that includes the effects of a rotor. Evaluation of different slot heights and jet velocity ratios were performed. Direct comparisons between an isolated fuselage and rotor/fuselage simulations were made showing similar flow control performance at a -3deg fuselage angle-of-attack condition. However, this was not the case for a -5deg angle-of-attack condition where the performance between the isolated fuselage and rotor/fuselage were different. The fuselage flow control resulted in a 17% drag reduction for a peak C(sub mu) of 0.0069 in a forward flight simulation where mu = 0:35 and CT/sigma = 0:08. The CFD flow control results also predicted a favorable 22% reduction of the fuselage download at this same condition, which can have beneficial compounding effects on the overall performance of the vehicle. This numerical investigation was performed in order to provide guidance for a future 1/3 scale wind tunnel experiment to be performed at the NASA 14-by 22-Foot Subsonic Tunnel.

  17. Program user's manual for an unsteady helicopter rotor-fuselage aerodynamic analysis

    NASA Technical Reports Server (NTRS)

    Lorber, Peter F.

    1988-01-01

    The Rotor-Fuselage Analysis is a method of calculating the aerodynamic reaction between a helicopter rotor and fuselage. This manual describes the structure and operation of the computer programs that make up the Rotor-Fuselage Analysis, programs which prepare the input and programs which display the output.

  18. Boeing EX Concept, Advanced Surveillance Aircraft

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The photograph shows a model of the Boeing EX Concept installed in the NASA Langley 16 foot Transonic Tunnel. The Boeing EX is an advanced surveillance aircraft proposed by Boeing to replace the Grumman E-2C Hawkeye. The concept employs the diamond-shape 'joined-wing'planform and active aperture radar arrays in each wing segment to create a more aerodynamic effective surveillance aircraft. Wind tunnel testing was conducted to evaulate longitudinal and lateral aerodynamic charcteristics and the effectiveness of control surface deflections. Measurements were made to determine the effects of the wings and fuselage on the inlet fan face total pressure distortions at angle of attack and sideslip.

  19. Structureborne noise measurements on a small twin-engine aircraft

    NASA Astrophysics Data System (ADS)

    Cole, J. E., III; Martini, K. F.

    1988-06-01

    Structureborne noise measurements performed on a twin-engine aircraft (Beechcraft Baron) are reported. There are two overall objectives of the test program. The first is to obtain data to support the development of analytical models of the wing and fuselage, while the second is to evaluate effects of structural parameters on cabin noise. Measurements performed include structural and acoustic responses to impact excitation, structural and acoustic loss factors, and modal parameters of the wing. Path alterations include added mass to simulate fuel, variations in torque of bolts joining wing and fuselage, and increased acoustic absorption. Conclusions drawn regarding these measurements are presented.

  20. Concept for a large multi-mission amphibian aircraft

    NASA Technical Reports Server (NTRS)

    Vaughan, J. C., III; Earl, T. D.

    1979-01-01

    A very large aircraft has been proposed for meeting both civil cargo and military transport needs for 1995 and beyond. The concept includes a wide noncircular fuselage cross section with a low wing, thick inner wing section, fuselage-mounted engines, and an air cushion landing gear. The civil freighter operates independently of congested passenger airports, using sheltered water as a runway and a waterfront land site for parking and ground operations. The military transport can operate from a wide variety of surfaces and temporary bases. The air cushion landing gear weighs substantially less than conventional gear and permits the use of extended takeoff distance resulting in improved payload/gross weight ratio.

  1. Structureborne noise measurements on a small twin-engine aircraft

    NASA Technical Reports Server (NTRS)

    Cole, J. E., III; Martini, K. F.

    1988-01-01

    Structureborne noise measurements performed on a twin-engine aircraft (Beechcraft Baron) are reported. There are two overall objectives of the test program. The first is to obtain data to support the development of analytical models of the wing and fuselage, while the second is to evaluate effects of structural parameters on cabin noise. Measurements performed include structural and acoustic responses to impact excitation, structural and acoustic loss factors, and modal parameters of the wing. Path alterations include added mass to simulate fuel, variations in torque of bolts joining wing and fuselage, and increased acoustic absorption. Conclusions drawn regarding these measurements are presented.

  2. New mathematical model for error reduction of stressed lap

    NASA Astrophysics Data System (ADS)

    Zhao, Pu; Yang, Shuming; Sun, Lin; Shi, Xinyu; Liu, Tao; Jiang, Zhuangde

    2016-05-01

    Stressed lap, compared to traditional polishing methods, has high processing efficiency. However, this method has disadvantages in processing nonsymmetric surface errors. A basic-function method is proposed to calculate parameters for a stressed-lap polishing system. It aims to minimize residual errors and is based on a matrix and nonlinear optimization algorithm. The results show that residual root-mean-square could be >15% after one process for classical trefoil error. The surface period errors close to the lap diameter were removed efficiently, up to 50% material removal.

  3. Uncertain structural dynamics of aircraft panels and fuzzy structures analysis

    NASA Astrophysics Data System (ADS)

    Sparrow, Victor W.; Buehrle, Ralph D.

    2002-11-01

    Aircraft fuselage panels, seemingly simple structures, are actually complex because of the uncertainty of the attachments of the frame stiffeners and longitudinal stringers. It is clearly important to understand the dynamics of these panels because of the subsequent radiation into the passenger cabin, even when complete information is not available for all portions of the finite-element model. Over the last few years a fuzzy structures analysis (FSA) approach has been undertaken at Penn State and NASA Langley to quantify the uncertainty in modeling aircraft panels. A new MSC.Nastran [MSC.Software Corp. (Santa Ana, CA)] Direct Matrix Abstraction Program (DMAP) code was written and tested [AIAA paper 2001-1320, 42nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conf., Seattle, WA, 16 April 2001] and was applied to simple fuselage panel models [J. Acoust. Soc. Am. 109, 2410(A) (2001)]. Recently the work has focused on understanding the dynamics of a realistic aluminum fuselage panel, typical of today's aircraft construction. This presentation will provide an overview of the research and recent results will be given for the fuselage panel. Comparison between experiments and the FSA results will be shown for different fuzzy input parameters. [Work supported by NASA Research Cooperative Agreement NCC-1-382.

  4. Machine Shop I. Learning Activity Packets (LAPs). Section A--Orientation.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains two learning activity packets (LAPs) for the "orientation and safety" instructional area of a Machine Shop I course. The two LAPs cover the following topics: orientation and general shop safety. Each LAP contains a cover sheet that describes its purpose, an introduction, and the tasks included in the LAP; learning steps…

  5. Machine Shop I. Learning Activity Packets (LAPs). Section C--Hand and Bench Work.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains two learning activity packets (LAPs) for the "hand and bench work" instructional area of a Machine Shop I course. The two LAPs cover the following topics: hand and bench work and pedestal grinder. Each LAP contains a cover sheet that describes its purpose, an introduction, and the tasks included in the LAP; learning steps…

  6. Machine Shop I. Learning Activity Packets (LAPs). Section D--Power Saws and Drilling Machines.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains two learning activity packets (LAPs) for the "power saws and drilling machines" instructional area of a Machine Shop I course. The two LAPs cover the following topics: power saws and drill press. Each LAP contains a cover sheet that describes its purpose, an introduction, and the tasks included in the LAP; learning steps…

  7. Manufacturing scale-up of composite fuselage crown panels

    NASA Technical Reports Server (NTRS)

    Willden, Kurtis; Gessel, M.; Grant, Carroll G.; Brown, T.

    1993-01-01

    The goal of the Boeing effort under the NASA ACT program is to reduce manufacturing costs of composite fuselage structure. Materials, fabrication of complex subcomponents and assembly issues are expected to drive the costs of composite fuselage structure. Several manufacturing concepts for the crown section of the fuselage were evaluated through the efforts of a Design Build Team (DBT). A skin-stringer-frame intricate bond design that required no fasteners for the panel assembly was selected for further manufacturing demonstrations. The manufacturing processes selected for the intricate bond design include Advanced Tow Placement (ATP) for multiple skin fabrication, resin transfer molding (RTM) of fuselage frames, innovative cure tooling, and utilization of low-cost material forms. Optimization of these processes for final design/manufacturing configuration was evaluated through the fabrication of several intricate bond panels. Panels up to 7 ft. by 10 ft. in size were fabricated to simulate half scale production parts. The qualitative and quantitative results of these manufacturing demonstrations were used to assess manufacturing risks and technology readiness for production.

  8. RWF rotor-wake-fuselage code software reference guide

    NASA Technical Reports Server (NTRS)

    Berry, John D.

    1991-01-01

    The RWF (Rotor-Wake-Fuselage) code was developed from first principles to compute the aerodynamics associated with the complex flow field of helicopter configurations. The code is sized for a single, multi-bladed main rotor and any configuration of non-lifting fuselage. The mathematical model for the RWF code is based on the integration of the momentum equations and Green's theorem. The unknowns in the problem are the strengths of prescribed singularity distributions on the boundaries of the flow. For the body (fuselage) a surface of constant strength source panels is used. For the rotor blades and rotor wake a surface of constant strength doublet panels is used. The mean camber line of the rotor airfoil is partitioned into surface panels. The no-flow boundary condition at the panel centroids is modified at each azimuthal step to account for rotor blade cyclic pitch variation. The geometry of the rotor wake is computers at each time step of the solution. The code produces rotor and fuselage surface pressures, as well as the complex geometry of the evolving rotor wake.

  9. An oblique view of the forward fuselage and port side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    An oblique view of the forward fuselage and port side of the Orbiter Discovery while mounted atop the 76-wheeled orbiter transfer system as it is being rolled from the Orbiter Processing Facility to the Vehicle Assembly Building at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  10. An oblique view of the forward fuselage and starboard side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    An oblique view of the forward fuselage and starboard side of the Orbiter Discovery while mounted atop the 76-wheeled orbiter transfer system as it is being rolled from the Orbiter Processing Facility to the Vehicle Assembly Building at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  11. Computational fire modeling for aircraft fire research

    SciTech Connect

    Nicolette, V.F.

    1996-11-01

    This report summarizes work performed by Sandia National Laboratories for the Federal Aviation Administration. The technical issues involved in fire modeling for aircraft fire research are identified, as well as computational fire tools for addressing those issues, and the research which is needed to advance those tools in order to address long-range needs. Fire field models are briefly reviewed, and the VULCAN model is selected for further evaluation. Calculations are performed with VULCAN to demonstrate its applicability to aircraft fire problems, and also to gain insight into the complex problem of fires involving aircraft. Simulations are conducted to investigate the influence of fire on an aircraft in a cross-wind. The interaction of the fuselage, wind, fire, and ground plane is investigated. Calculations are also performed utilizing a large eddy simulation (LES) capability to describe the large- scale turbulence instead of the more common k-{epsilon} turbulence model. Additional simulations are performed to investigate the static pressure and velocity distributions around a fuselage in a cross-wind, with and without fire. The results of these simulations provide qualitative insight into the complex interaction of a fuselage, fire, wind, and ground plane. Reasonable quantitative agreement is obtained in the few cases for which data or other modeling results exist Finally, VULCAN is used to quantify the impact of simplifying assumptions inherent in a risk assessment compatible fire model developed for open pool fire environments. The assumptions are seen to be of minor importance for the particular problem analyzed. This work demonstrates the utility of using a fire field model for assessing the limitations of simplified fire models. In conclusion, the application of computational fire modeling tools herein provides both qualitative and quantitative insights into the complex problem of aircraft in fires.

  12. INTERIOR OF WEST SPAN LOOKING WEST (SHADOW OF VERTICAL LAPS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR OF WEST SPAN LOOKING WEST (SHADOW OF VERTICAL LAPS PLACED ON ZONE III; ASPHALT ZONE IX) - Honey Run Bridge, Spanning Butte Creek, bypassed section of Honey Run Road (originally Carr Hill Road), Paradise, Butte County, CA

  13. FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.; Simmons, Kevin L.

    2015-02-16

    Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribe welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.

  14. Smart structure application for the Challenger aircraft

    NASA Astrophysics Data System (ADS)

    Grenier, L.; Blaha, Franz A.

    1994-09-01

    The Challenger aircraft fleet of the Canadian Forces will fly demanding missions, requiring the implementation of a fatigue management program based on the monitoring of in-flight aircraft load conditions. Conventional sensing techniques experience problems arising from severe electromagnetic interference (EMI). This paper describes the development of an EMI- insensitive smart-structure sensing concept for loads monitoring. Fiber-optic strain sensors, incorporated at critical structural locations, are used to monitor the fatigue life of the aircraft wing, fuselage, and empennage. A fiber-optic accelerometer is also incorporated in the system. A long-term plan is presented for the development of an advanced smart-structure concept which can support the continuous monitoring of fatigue-prone components, and provide the aircraft with near real-time damage location and assessment.

  15. A comparison of the aerodynamic characteristics at transonic speeds of four wing-fuselage configurations as determined from different test techniques, 4 October 1960

    NASA Technical Reports Server (NTRS)

    Donlan, C. J.; Myers, B. C., II; Mattson, A. T.

    1976-01-01

    The high speed aerodynamic characteristics of a family of four wing-fuselage configurations of 0, 35, 45, and 60 deg sweepback were determined from transonic bump model tests that were conducted in the Langley high speed 7 by 10 foot tunnel; sting supported model tests were conducted in the Langley 8 foot high speed tunnel and in the Langley high speed 7 by 10 foot tunnel, and rocket model tests were conducted by the Langley Pilotless Aircraft Research Division. A complementary study of the effect of Mach number gradients and streamline curvature on bump results is also included. The qualitative data obtained from the various test facilities for the wing-fuselage configurations were in essential agreement as regards the relative effects of sweepback and Mach number except for drag at zero lift. Quantitatively, important differences were present.

  16. Adhesive-bonded scarf and stepped-lap joints

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1973-01-01

    Continuum mechanics solutions are derived for the static load-carrying capacity of scarf and stepped-lap adhesive-bonded joints. The analyses account for adhesive plasticity and adherend stiffness imbalance and thermal mismatch. The scarf joint solutions include a simple algebraic formula which serves as a close lower bound, within a small fraction of a per cent of the true answer for most practical geometries and materials. Digital computer programs were developed and, for the stepped-lap joints, the critical adherend and adhesive stresses are computed for each step. The scarf joint solutions exhibit grossly different behavior from that for double-lap joints for long overlaps inasmuch as that the potential bond shear strength continues to increase with indefinitely long overlaps on the scarf joints. The stepped-lap joint solutions exhibit some characteristics of both the scarf and double-lap joints. The stepped-lap computer program handles arbitrary (different) step lengths and thickness and the solutions obtained have clarified potentially weak design details and the remedies. The program has been used effectively to optimize the joint proportions.

  17. Using the LAPS / WRF system to Analyze and Forecast Solar Radiation

    NASA Astrophysics Data System (ADS)

    Albers, S. C.; Xie, Y.; Jiang, H.; Toth, Z.

    2012-12-01

    The Local Analysis and Prediction System (LAPS) is being used to produce rapid update, high resolution analyses and forecasts of solar radiation (Global Horizontal Irradiance or GHI). LAPS is highly portable and can be run onsite, particularly when high-resolution and rapid updating is needed. This allows the user to assimilate their own observational data merged with centrally available observations and to set up the analysis/forecast configuration to their liking. The cloud analysis uses satellite (including IR and 1-km resolution visible imagery, updated every 15-min), METARs, radar, aircraft and model first guess information to produce an hourly 3-D field of cloud fraction, cloud liquid, and cloud ice. The cloud analysis and satellite data together are used to produce a gridded analysis of total solar radiation. This is verified against a dense network of real-time solar radiation measurements that are independent (not used in the analysis). We are focusing mainly on a two nested domains covering the Southern Plains states that encompass networks of pyranometers located in Oklahoma and Texas. The GHI forecast is being run on the outer domain, and is being initialized using the same cloud analysis package that drives the analysis fields mentioned above. The HWT domain initializes WRF every hour with 15-minute output. Real-time verification of the analyses (including images of the analysis), and forecasts can be seen on our website, and updated results will be explored in this presentation.

  18. Using the LAPS / WRF system to Analyze and Forecast Solar Radiation

    NASA Astrophysics Data System (ADS)

    Albers, S. C.; Jankov, I.

    2011-12-01

    The LAPS system is being used to produce rapid update, high resolution analyses and forecasts of solar radiation. The cloud analysis uses satellite, METARs, radar, aircraft and model first guess information to produce an hourly 3-D field of cloud fraction, cloud liquid, and cloud ice. The cloud analysis and satellite data together are used to produce a gridded analysis of total solar radiation. This is verified against solar radiation measurements that are independent (not used in the analysis). Two domains are being run and verified at present. The one with the most stations covers the Oklahoma mesonet with about 100 pyranometers. The total solar radiation forecast is being run on two domains, and is being initialized using the same cloud analysis package that drives the analysis fields mentioned above. The Colorado domain produces hourly forecasts, initialized every 6 hours. It is verified with about 20 Oklahoma mesonet stations. The HWT domain initializes WRF every 2 hours, with 15-minute output. Forecasts are being compared with the Oklahoma mesonet. Real-time verification of the analyses (including images of the analysis), and forecasts can be seen on our website 'laps.noaa.gov', and will be explored in this presentation.

  19. Modified Convair-240 aircraft at Naval Weapons Center, China Lake, California

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Convair-240 aircraft modified to fill role of a Space Shuttle is parked outside aircraft hangar at Naval Weapons Center, China Lake, California. Space shuttle side hatch mockup is incorporated in fuselage (visible toward the aft section of the aircraft). Convair-240 aircraft is part of November crew escape system (CES) testing of a candidate concept developed to provide crew egress capability during Space Shuttle controlled gliding flight. Tractor rocket testing using the Convair-240 will begin 11-20-87. Life-like dummies will be pulled by the rockets from the modified aircraft's side hatch mockup.

  20. A scan-angle correction for thermal infrared multispectral data using side lapping images

    USGS Publications Warehouse

    Watson, K.

    1996-01-01

    Thermal infrared multispectral scanner (TIMS) images, acquired with side lapping flight lines, provide dual angle observations of the same area on the ground and can thus be used to estimate variations in the atmospheric transmission with scan angle. The method was tested using TIMS aircraft data for six flight lines with about 30% sidelap for an area within Joshua Tree National Park, California. Generally the results correspond to predictions for the transmission scan-angle coefficient based on a standard atmospheric model although some differences were observed at the longer wavelength channels. A change was detected for the last pair of lines that may indicate either spatial or temporal atmospheric variation. The results demonstrate that the method provides information for correcting regional survey data (requiring multiple adjacent flight lines) that can be important in detecting subtle changes in lithology.

  1. GEMPAK: An arbitrary aircraft geometry generator

    NASA Technical Reports Server (NTRS)

    Stack, S. H.; Edwards, C. L. W.; Small, W. J.

    1977-01-01

    A computer program, GEMPAK, has been developed to aid in the generation of detailed configuration geometry. The program was written to allow the user as much flexibility as possible in his choices of configurations and the detail of description desired and at the same time keep input requirements and program turnaround and cost to a minimum. The program consists of routines that generate fuselage and planar-surface (winglike) geometry and a routine that will determine the true intersection of all components with the fuselage. This paper describes the methods by which the various geometries are generated and provides input description with sample input and output. Also included are descriptions of the primary program variables and functions performed by the various routines. The FORTRAN program GEMPAK has been used extensively in conjunction with interfaces to several aerodynamic and plotting computer programs and has proven to be an effective aid in the preliminary design phase of aircraft configurations.

  2. Acoustic measurements of F-4E aircraft operating in hush house, NSN 4920-02-070-2721

    NASA Astrophysics Data System (ADS)

    Miller, V. R.; Plzak, G. A.; Chinn, J. M.

    1981-09-01

    The primary purpose of this test program was to measure the acoustic environment in the hush house facility located at Kelly Air Force Base, Texas, during operation of the F-4E aircraft to ensure that aircraft structural acoustic design limits were not exceeded. The acoustic measurements showed that sonic fatigue problems are anticipated with the F-4E aircraft aft fuselage structure during operation in the hush house. The measured acoustic levels were less than those measured in an F-4E aircraft water cooled hush house at Hill AFB in the lower frequencies, but were increased over that measured during ground run up on some areas of the aircraft. It was recommended that the acoustic loads measured in this program should be specified in the structural design criteria for aircraft which will be subjected to hush house operation or defining requirements for associated equipment. Recommendations were also made to increase the fatigue life of the aft fuselage.

  3. Flaw Tolerance in Lap Shear Brazed Joints. Part 1

    NASA Technical Reports Server (NTRS)

    Flom, Yury; Wang, Li-Qin

    2003-01-01

    Furnace brazing is a joining process used in the aerospace and other industries to produce strong permanent and hermetic structural joints. As in any joining process, brazed joints have various imperfections and defects. At the present time, our understanding of the influence of the internal defects on the strength of the brazed joints is not adequate. The goal of this 3-part investigation is to better understand the properties and failure mechanisms of the brazed joints containing defects. This study focuses on the behavior of the brazed lap shear joints because of their importance in manufacturing aerospace structures. In Part 1, an average shear strength capability and failure modes of the single lap joints are explored. Stainless steel specimens brazed with pure silver are tested in accordance with the AWS C3.2 standard. Comparison of the failure loads and the ultimate shear strength with the Finite Element Analysis (FEA) of the same specimens as a function of the overlap widths shows excellent correlation between the experimental and calculated values for the defect-free lap joints. A damage zone criterion is shown to work quite well in understanding the failure of the braze joints. In Part 2, the findings of the Part 1 will be verified on the larger test specimens. Also, various flaws will be introduced in the test specimens to simulate lack of braze coverage in the lap joints. Mechanical testing and FEA will be performed on these joints to verify that behavior of the flawed ductile lap joints is similar to joints with a reduced braze area. Finally, in Part 3, the results obtained in Parts 1 and 2 will be applied to the actual brazed structure to evaluate the load-carrying capability of a structural lap joint containing discontinuities. In addition, a simplified engineering procedure will be offered for the laboratory testing of the lap shear specimens.

  4. Computing induced velocity perturbations due to a helicopter fuselage in a free stream

    NASA Technical Reports Server (NTRS)

    Berry, John D.; Althoff, Susan L.

    1989-01-01

    The velocity field of a representative helicopter fuselage in a free stream is computed. Perturbation velocities due to the fuselage are computed in a plan above the location of the helicopter rotor (rotor removed). The velocity perturbations computed by a source-panel model of the fuselage are compared with experimental measurements taken with a laser velocimeter. Three paneled fuselage models are studied: fuselage shape, fuselage shape with hub shape, and a body of revolution. The velocity perturbations computed for both fuselage shape models agree well with the measured velocity field except in the close vicinity of the rotor hub. In the hub region, without knowing the extent of separation, modeling of the effective source shape is difficult. The effects of the fuselage perturbations are not well-predicted with a simplified ellipsoid fuselage. The velocity perturbations due to the fuselage at the plane of the measurements have magnitudes of less than 8 percent of free-stream velocity. The velocity perturbations computed by the panel method are tabulated for the same locations at which previously reported rotor-inflow velocity measurements were made.

  5. Algebraic grid generation for wing-fuselage bodies

    NASA Technical Reports Server (NTRS)

    Smith, R. E.; Everton, E. L.; Kudlinski, R. A.

    1984-01-01

    An algebraic procedure for the generation of boundary-fitted grids about wing-fuselage configurations is presented. A wing-fuselage configuration is specified by cross sections and mathematically represented by Coons' patches. A configuration is divided into sections so that several grid blocks that either adjoin each other or partially overlap each other can be generated, and each grid has six surfaces that map into a computational cube. Grids are first determined on the six boundary surfaces and then in the interior. Grid curves that are on the surface of the configuration are derived using plane-patch intersections, and single-valued functions relating approximate arc lengths along the curves to computational coordinates define the distribution of grid points. The two-boundary technique and transfinite interpolation are used to determine the boundary surface grids that are not on the configuration, and transfinite interpolation with linear blending functions is used to determine the interior grids.

  6. Aerodynamic analysis of a helicopter fuselage with rotating rotor head

    NASA Astrophysics Data System (ADS)

    Reß, R.; Grawunder, M.; Breitsamter, Ch.

    2015-06-01

    The present paper describes results of wind tunnel experiments obtained during a research programme aimed at drag reduction of the fuselage of a twin engine light helicopter configuration. A 1 : 5 scale model of a helicopter fuselage including a rotating rotor head and landing gear was investigated in the low-speed wind tunnel A of Technische Universität a München (TUM). The modelled parts of the helicopter induce approxiu mately 80% of the total parasite drag thus forming a major potential for shape optimizations. The present paper compares results of force and moment measurements of a baseline configuration and modified variants with an emphasis on the aerodynamic drag, lift, and yawing moment coefficients.

  7. Skid Landings of Airplanes on Rocker-Type Fuselages

    NASA Technical Reports Server (NTRS)

    Mayo, Wilbur L.

    1961-01-01

    A study is made of the landing of an airplane on a fuselage with "planned" curvature of its lower surface. Initial contact is considered to stop the vertical motion of a point remote from the center of gravity, thus causing rocking on the curved lower surface which converts sinking-speed energy into angular energy in pitch for dissipation by damping forces. Analysis is made of loads and motions for a given fuselage shape, and the contours required to give desired load histories are determined. Most of the calculations involve initial contact at the tail, but there are two cases of unflared landings with initial contact at the nose. The calculations are checked experimentally for the tail - low case.

  8. Use of two-dimensional transmission photoelastic models to study stresses in double-lap bolted joints: Load transfer and stresses in the inner lap

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1980-01-01

    The determination of the stress distribution in the inner lap of double-lap, double-bolt joints using photoelastic models of the joint is discussed. The principal idea is to fabricate the inner lap of a photoelastic material and to use a photoelastically sensitive material for the two outer laps. With this setup, polarized light transmitted through the stressed model responds principally to the stressed inner lap. The model geometry, the procedures for making and testing the model, and test results are described.

  9. Closeup view of the upper exterior of the forward fuselage ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up view of the upper exterior of the forward fuselage of the Orbiter Discovery in the Orbiter Processing Facility at NASA's Kennedy Space Center. The view show a detail of the flight deck windows with protective covers installed to protect the window surfaces during processing. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  10. View of the forward fuselage and the reinforced carboncarbon nose ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of the forward fuselage and the reinforced carbon-carbon nose of the Orbiter Discovery looking aft while mounted atop the 76-wheeled orbiter transfer system as it is being rolled from the Orbiter Processing Facility to the Vehicle Assembly Building at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  11. Detailed view inside the aft fuselage of the Orbiter Discovery ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detailed view inside the aft fuselage of the Orbiter Discovery showing the network of supply, distribution and feed lines to deliver fuel, oxidizer and other vital gasses and fluids to the Space Shuttle Main Engines (SSMEs). This photograph was taken in the Orbiter Processing Facility at the Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  12. General view of the aft fuselage of the Orbiter Discovery ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of the aft fuselage of the Orbiter Discovery looking forward showing Space Shuttle Main Engines (SSMEs) installed in positions one and three and an SSME on the process of being installed in position two. This photograph was taken in the Orbiter Processing Facility at the Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  13. Rotorcraft Fuselage Flow Control Using Plasma Streamwise Vortex Generators

    NASA Astrophysics Data System (ADS)

    Coleman, Dustin; Thomas, Flint

    2012-11-01

    Active flow control, in the form of dielectric barrier discharge (DBD) plasma actuators, is applied to a NASA ROBIN-mod7 generic rotorcraft fuselage model. The model is considered in what would be a typical cruise position i.e. a nose down position at α = -5° . This configuration gives rise to a massive 3-D flow separation over the aft ramp section of the fuselage, characterized by two counter-rotating, streamwise vortices. The control objective is to minimize these concentrated vortices by means of flush fuselage-mounted plasma streamwise vortex generators (PSVGs), and consequently, reduce the form drag of the vehicle. Experiments were conducted at freestream Mach and Reynolds numbers of M∞ = 0 . 12 and ReL = 2 . 65 million, respectively. Aerodynamic loads under both natural and controlled conditions were acquired through use of an ATI Mini40 6-component force sensor. The pressure field on the ramp section was monitored by a 128 count static pressure array. Likewise, the flow field was captured by time-resolved PIV wake surveys. Results are compared with previous studies that utilized active flow control by way of pulsed jets or combustion actuators. This work is supported under NASA Cooperative Agreement NNX10AM32G.

  14. High Fidelity Failure Analysis for a Composite Fuselage Section

    NASA Technical Reports Server (NTRS)

    Li, Jain; Davila, Carlos G.; Chen, Tzi-Kang

    2001-01-01

    A high fidelity delamination failure analysis was developed by combining a local failure analysis with a global full-scale finite element structural analysis to address strength and delamination failure in a single package. The methodology was demonstrated through a local three-dimensional pull-off failure analysis and a geometrically nonlinear structural analysis of a five-foot composite helicopter fuselage section. Pull-off specimens were used to identify potential debonding failure of co-cured skin-stringer/frame fuselage structures. An investigation of the failed pull-off specimens was performed to determine the location of the failure initiation. Three-dimensional strain energy release rate analysis indicates that the delamination initiation and growth is controlled by Mode 1 opening mode. The bending moment at the delamination tip was identified as the crucial factor controlling the failure. The geometrically nonlinear structural analysis of a five-foot composite fuselage section was performed using a detailed finite element model. Loads were applied along the periphery of the subcomponent using displacement fields generated from solutions of a full-vehicle model.

  15. Test results from large wing and fuselage panels

    NASA Technical Reports Server (NTRS)

    Madan, Ram C.; Voldman, Mike

    1993-01-01

    This paper presents the first results in an assessment of the strength, stiffness, and damage tolerance of stiffened wing and fuselage subcomponents. Under this NASA funded program, 10 large wing and fuselage panels, variously fabricated by automated tow placement and dry-stitched preform/resin transfer molding, are to be tested. The first test of an automated tow placement six-longeron fuselage panel under shear load was completed successfully. Using NASTRAN finite-element analysis the stiffness of the panel in the linear range prior to buckling was predicted within 3.5 percent. A nonlinear analysis predicted the buckling load within 10 percent and final failure load within 6 percent. The first test of a resin transfer molding six-stringer wing panel under compression was also completed. The panel failed unexpectedly in buckling because of inadequate supporting structure. The average strain was 0.43 percent with a line load of 20.3 kips per inch of width. This strain still exceeds the design allowable strains. Also, the stringers did not debond before failure, which is in contrast to the general behavior of unstitched panels.

  16. Skin, Stringer, and Fastener Loads in Buckled Fuselage Panels

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Rose, Cheryl A.; Starnes, James H., Jr.

    2001-01-01

    The results of a numerical study to assess the effect of skin buckling on the internal load distribution in a stiffened fuselage panel, with and without longitudinal cracks, are presented. In addition, the impact of changes in the internal loads on the fatigue life and residual strength of a fuselage panel is assessed. A generic narrow-body fuselage panel is considered. The entire panel is modeled using shell elements and considerable detail is included to represent the geometric-nonlinear response of the buckled skin, cross section deformation of the stiffening components, and details of the skin-string attachment with discrete fasteners. Results are presented for a fixed internal pressure and various combinations of axial tension or compression loads. Results illustrating the effect of skin buckling on the stress distribution in the skin and stringer, and fastener loads are presented. Results are presented for the pristine structure, and for cases where damage is introduced in the form of a longitudinal crack adjacent to the stringer, or failed fastener elements. The results indicate that axial compression loads and skin buckling can have a significant effect on the circumferential stress in the skin, and fastener loads, which will influence damage initiation, and a comparable effect on stress intensity factors for cases with cracks. The effects on stress intensity factors will influence damage propagation rates and the residual strength of the panel.

  17. Damage detection in aircraft structures using dynamically measured static flexibility matrices

    SciTech Connect

    Robinson, N.A.; Peterson, L.D.; James, G.H.; Doebling, S.W.

    1996-02-01

    Two methods for detecting the location of structural damage in an aircraft fuselage using modal test data are presented. Both methods use the dynamically measured static flexibility matrix, which is assembled from a combination of measured modal vectors, frequencies, and driving point residual flexibilities. As a consequence, neither method requires a mode-to-mode correlation, and both avoid tedious modal discrimination and selection. The first method detects damage as a softening in the point flexibility components, which are the diagonal entries in the flexibility matrix. The second method detects damage from the disassembled elemental stiffnesses as determined using a presumed connectivity. Vibration data from a laser vibrometer is used to measure the modal mechanics of a DC9 aircraft fuselage before and after induced weakening in a longitudinal stringer. Both methods are shown to detect the location of the damage, primarily because the normal stiffness of the reinforced shell of the fuselage is localized to a few square centimeters.

  18. V/STOL tilt rotor aircraft study mathematical model for a real time simulation of a tilt rotor aircraft (Boeing Vertol Model 222), volume 8

    NASA Technical Reports Server (NTRS)

    Rosenstein, H.; Mcveigh, M. A.; Mollenkof, P. A.

    1973-01-01

    A mathematical model for a real time simulation of a tilt rotor aircraft was developed. The mathematical model is used for evaluating aircraft performance and handling qualities. The model is based on an eleven degree of freedom total force representation. The rotor is treated as a point source of forces and moments with appropriate response time lags and actuator dynamics. The aerodynamics of the wing, tail, rotors, landing gear, and fuselage are included.

  19. LAP5 and LAP6 encode anther-specific proteins with similarity to chalcone synthase essential for pollen exine development in Arabidopsis.

    PubMed

    Dobritsa, Anna A; Lei, Zhentian; Nishikawa, Shuh-Ichi; Urbanczyk-Wochniak, Ewa; Huhman, David V; Preuss, Daphne; Sumner, Lloyd W

    2010-07-01

    Pollen grains of land plants have evolved remarkably strong outer walls referred to as exine that protect pollen and interact with female stigma cells. Exine is composed of sporopollenin, and while the composition and synthesis of this biopolymer are not well understood, both fatty acids and phenolics are likely components. Here, we describe mutations in the Arabidopsis (Arabidopsis thaliana) LESS ADHESIVE POLLEN (LAP5) and LAP6 that affect exine development. Mutation of either gene results in abnormal exine patterning, whereas pollen of double mutants lacked exine deposition and subsequently collapsed, causing male sterility. LAP5 and LAP6 encode anther-specific proteins with homology to chalcone synthase, a key flavonoid biosynthesis enzyme. lap5 and lap6 mutations reduced the accumulation of flavonoid precursors and flavonoids in developing anthers, suggesting a role in the synthesis of phenolic constituents of sporopollenin. Our in vitro functional analysis of LAP5 and LAP6 using 4-coumaroyl-coenzyme A yielded bis-noryangonin (a commonly reported derailment product of chalcone synthase), while similar in vitro analyses using fatty acyl-coenzyme A as the substrate yielded medium-chain alkyl pyrones. Thus, in vitro assays indicate that LAP5 and LAP6 are multifunctional enzymes and may play a role in both the synthesis of pollen fatty acids and phenolics found in exine. Finally, the genetic interaction between LAP5 and an anther gene involved in fatty acid hydroxylation (CYP703A2) demonstrated that they act synergistically in exine production. PMID:20442277

  20. Fabrication of the V-22 composite AFT fuselage using automated fiber placement

    NASA Technical Reports Server (NTRS)

    Pinckney, Robert L.

    1991-01-01

    Boeing Helicopters and its subcontractors are working together under an Air Force Wright Research and Development Center (WRDC)-Manufacturing-Technology Large-Composite Primary Structure Fuselage program to develop and demonstrate new manufacturing techniques for producing composite fuselage skin and frame structures. Three sets of aft fuselage skins and frames have been fabricated and assembled, and substantial reductions in fabrication and assembly costs demonstrated.

  1. Wind tunnel investigation of helicopter-rotor wake effects on three helicopter fuselage models

    NASA Technical Reports Server (NTRS)

    Wilson, J. C.; Mineck, R. E.

    1975-01-01

    The effects of rotor wake on helicopter fuselage aerodynamic characteristics were investigated in the Langley V/STOL tunnel. Force, moment, and pressure data were obtained on three fuselage models at various combinations of windspeed, sideslip angle, and pitch angle. The data show that the influence of rotor wake on the helicopter fuselage yawing moment imposes a significant additional thrust requirement on the tail rotor of a single-rotor helicopter at high sideslip angles.

  2. Lap time optimisation of a racing go-kart

    NASA Astrophysics Data System (ADS)

    Lot, Roberto; Dal Bianco, Nicola

    2016-02-01

    The minimum lap time optimal control problem has been solved for a go-kart model. The symbolic algebra software Maple has been used to derive equations of motion and an indirect method has been adopted to solve the optimal control problem. Simulation has been successfully performed on a full track lap with a multibody model endowed with seven degrees of freedom. Geometrical and mechanical characteristics of a real kart have been measured by a lab test to feed the mathematical model. Telemetry recorded in an entire lap by a professional driver has been compared to simulation results in order to validate the model. After the reliability of the optimal control model was proved, the simulation has been used to study the peculiar dynamics of go-karts and focus to tyre slippage dynamics, which is highly affected by the lack of differential.

  3. Review on failure prediction techniques of composite single lap joint

    NASA Astrophysics Data System (ADS)

    Ab Ghani A., F.; Rivai, Ahmad

    2016-03-01

    Adhesive bonding is the most appropriate joining method in construction of composite structures. The use of reliable design and prediction technique will produce better performance of bonded joints. Several papers from recent papers and journals have been reviewed and synthesized to understand the current state of the art in this area. It is done by studying the most relevant analytical solutions for composite adherends with start of reviewing the most fundamental ones involving beam/plate theory. It is then extended to review single lap joint non linearity and failure prediction and finally on the failure prediction on composite single lap joint. The review also encompasses the finite element modelling part as tool to predict the elastic response of composite single lap joint and failure prediction numerically.

  4. Novel virtual Lap-Band simulator could promote patient safety.

    PubMed

    De, Suvranu; Ahn, Woojin; Lee, Doo Yong; Jones, Daniel B

    2008-01-01

    This paper presents, for the first time, a physics-based modeling technique for the Lap-Band (Inamed Health) used in laparoscopic gastric banding (LAGB) operations for treating the morbidly obese. A virtual LAGB simulator can help train medical students as well as surgeons who embark at learning this relatively new operation. The Lap-Band has different thickness and curvature along the centerline, and therefore leads to different deformation behaviors. A hybrid modeling strategy is therefore adopted to successfully replicate its dynamics. A mass-spring model, used to model the less stiff part, is coupled to a quasi-static articulated link model for the more stiff and inextensible part. The virtual Lap-Band model has been implemented into a complete graphics-haptics-physics-based system with two PHANToM Omni devices (from Sensible Technologies) being used for real-time bimanual interaction with force feedback. PMID:18391265

  5. Rapid Parameterization Schemes for Aircraft Shape Optimization

    NASA Technical Reports Server (NTRS)

    Li, Wu

    2012-01-01

    A rapid shape parameterization tool called PROTEUS is developed for aircraft shape optimization. This tool can be applied directly to any aircraft geometry that has been defined in PLOT3D format, with the restriction that each aircraft component must be defined by only one data block. PROTEUS has eight types of parameterization schemes: planform, wing surface, twist, body surface, body scaling, body camber line, shifting/scaling, and linear morphing. These parametric schemes can be applied to two types of components: wing-type surfaces (e.g., wing, canard, horizontal tail, vertical tail, and pylon) and body-type surfaces (e.g., fuselage, pod, and nacelle). These schemes permit the easy setup of commonly used shape modification methods, and each customized parametric scheme can be applied to the same type of component for any configuration. This paper explains the mathematics for these parametric schemes and uses two supersonic configurations to demonstrate the application of these schemes.

  6. Analysis and Design of Fuselage Structures Including Residual Strength Prediction Methodology

    NASA Technical Reports Server (NTRS)

    Knight, Norman F.

    1998-01-01

    The goal of this research project is to develop and assess methodologies for the design and analysis of fuselage structures accounting for residual strength. Two primary objectives are included in this research activity: development of structural analysis methodology for predicting residual strength of fuselage shell-type structures; and the development of accurate, efficient analysis, design and optimization tool for fuselage shell structures. Assessment of these tools for robustness, efficient, and usage in a fuselage shell design environment will be integrated with these two primary research objectives.

  7. Advanced air transport concepts. [review of design methods for very large aircraft

    NASA Technical Reports Server (NTRS)

    Molloy, J. K.

    1979-01-01

    The concepts of laminar flow control, very large all-wing aircraft, an aerial relay transportation system and alternative fuels, which would enable large improvements in fuel conservation in air transportation in the 1990's are discussed. Laminar boundary layer control through suction would greatly reduce skin friction and has been reported to reduce fuel consumption by up to 29%. Distributed load aircraft, in which all fuel and payload are carried in the wing and the fuselage is absent, permit the use of lighter construction materials and the elimination of fuselage and tail drag. Spanloader aircraft with laminar flow control could be used in an aerial relay transportation system which would employ a network of continuously flying liners supplied with fuel, cargo and crews by smaller feeder aircraft. Liquid hydrogen and methane fuels derived from coal are shown to be more weight efficient and less costly than coal-derived synthetic jet fuels.

  8. Characterization studies on the additives mixed L-arginine phosphate monohydrate (LAP) crystals

    NASA Astrophysics Data System (ADS)

    Haja Hameed, A. S.; Karthikeyan, C.; Ravi, G.; Rohani, S.

    2011-04-01

    L-arginine phosphate monohydrate (LAP), potassium thiocyanate (KSCN) mixed LAP (LAP:KSCN) and sodium sulfite (Na 2SO 3) mixed LAP (LAP:Na 2SO 3) single crystals were grown by slow cooling technique. The effect of microbial contamination and coloration on the growth solutions was studied. The crystalline powders of the grown crystals were examined by X-ray diffraction and the lattice parameters of the crystals were estimated. From the FTIR spectroscopic analysis, various functional group frequencies associated with the crystals were assigned. Vickers microhardness studies were done on {1 0 0} faces for pure and additives mixed LAP crystals. From the preliminary surface second harmonic generation (SHG) results, it was found that the SHG intensity at (1 0 0) face of LAP:KSCN crystal was much stronger than that of pure LAP.

  9. Seam-Tracking for Friction Stir Welded Lap Joints

    NASA Astrophysics Data System (ADS)

    Fleming, Paul A.; Hendricks, Christopher E.; Cook, George E.; Wilkes, D. M.; Strauss, Alvin M.; Lammlein, David H.

    2010-11-01

    This article presents a method for automatic seam-tracking in friction stir welding (FSW) of lap joints. In this method, tracking is accomplished by weaving the FSW tool back-and-forth perpendicular to the direction of travel during welding and monitoring force and torque signals. Research demonstrates the ability of this method to automatically track weld seam positions. Additionally, tensile and S-bend test result comparisons demonstrate that weaving most likely does not reduce weld quality. Finally, benefits of this weave-based method to FSW of lap joints are discussed and methods for incorporating it into existing friction stir welding control algorithms (such as axial load control) are examined.

  10. Effects of bearing surfaces on lap joint energy dissipation

    SciTech Connect

    Kess, H. R.; Rosnow, N. J.; Sidle, B. C.

    2001-01-01

    Energy is dissipated in mechanical systems in several forms. The major contributor to damping in bolted lap joints is friction, and the level of damping is a function of stress distribution in the bearing surfaces. This study examines the effects of bearing surface configuration on lap joint energy dissipation. The examination is carried out through the analysis of experimental results in a nonlinear framework. Then finite element models are constructed in a nonlinear framework to simulate the results. The experimental data were analyzed using piecewise linear log decrement. Phenomenological and non-phenomenological mathematical models were used to simulate joint behavior. Numerical results of experiments and analyses are presented.

  11. Static and fatigue testing of full-scale fuselage panels fabricated using a Therm-X(R) process

    NASA Technical Reports Server (NTRS)

    Dinicola, Albert J.; Kassapoglou, Christos; Chou, Jack C.

    1992-01-01

    Large, curved, integrally stiffened composite panels representative of an aircraft fuselage structure were fabricated using a Therm-X process, an alternative concept to conventional two-sided hard tooling and contour vacuum bagging. Panels subsequently were tested under pure shear loading in both static and fatigue regimes to assess the adequacy of the manufacturing process, the effectiveness of damage tolerant design features co-cured with the structure, and the accuracy of finite element and closed-form predictions of postbuckling capability and failure load. Test results indicated the process yielded panels of high quality and increased damage tolerance through suppression of common failure modes such as skin-stiffener separation and frame-stiffener corner failure. Finite element analyses generally produced good predictions of postbuckled shape, and a global-local modelling technique yielded failure load predictions that were within 7% of the experimental mean.

  12. Propeller tip vortex - A possible contributor to aircraft cabin noise

    NASA Astrophysics Data System (ADS)

    Miller, B. A.; Dittmar, J. H.; Jeracki, R. J.

    1982-01-01

    Wind tunnel model tests support the hypothesis that a propeller tip vortex may subject a downstream wing surface to greater excitation than would be experienced by the aircraft fuselage side wall exposed to propeller-generated noise, ultimately transmitting this structural response to incident dynamic pressure to the cabin interior. Even if structure-borne excitations are less efficient than airborne excitations in the creation of cabin noise, the higher level of the former could still govern cabin noise levels.

  13. Preliminary design studies of an advanced general aviation aircraft

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Preliminary design studies are presented for an advanced general aviation aircraft. Advanced guidance and display concepts, laminar flow, smart structures, fuselage and wing structural design and manufacturing, and preliminary configuration design are discussed. This project was conducted as a graduate level design class under the auspices of the KU/NASA/USRA Advanced Design Program in Aeronautics. The results obtained during the fall semester of 1990 (Phase 1) and the spring semester of 1991 (Phase 2) are presented.

  14. An analytic modeling and system identification study of rotor/fuselage dynamics at hover

    NASA Technical Reports Server (NTRS)

    Hong, Steven W.; Curtiss, H. C., Jr.

    1993-01-01

    A combination of analytic modeling and system identification methods have been used to develop an improved dynamic model describing the response of articulated rotor helicopters to control inputs. A high-order linearized model of coupled rotor/body dynamics including flap and lag degrees of freedom and inflow dynamics with literal coefficients is compared to flight test data from single rotor helicopters in the near hover trim condition. The identification problem was formulated using the maximum likelihood function in the time domain. The dynamic model with literal coefficients was used to generate the model states, and the model was parametrized in terms of physical constants of the aircraft rather than the stability derivatives, resulting in a significant reduction in the number of quantities to be identified. The likelihood function was optimized using the genetic algorithm approach. This method proved highly effective in producing an estimated model from flight test data which included coupled fuselage/rotor dynamics. Using this approach it has been shown that blade flexibility is a significant contributing factor to the discrepancies between theory and experiment shown in previous studies. Addition of flexible modes, properly incorporating the constraint due to the lag dampers, results in excellent agreement between flight test and theory, especially in the high frequency range.

  15. In-flight measurement of propeller noise on the fuselage of an airplane

    NASA Technical Reports Server (NTRS)

    Pla, Frederic G.; Ranaudo, Richard; Woodward, Richard P.

    1989-01-01

    In-flight measurements of propeller noise on the fuselage of an OV-10A aircraft were obtained using a horizontal and a vertical microphone array. A wide range of flight conditions were tested including changes in angle of attack, sideslip angle, power coefficient, helical tip Mach number and advance ratio, and propeller direction of rotation. Results show a dependence of the level and directivity of the tones on the angle of attack and on the sideslip angle with the propeller direction of rotation, which is similar to results obtained in wind tunnel tests with advanced propeller designs. The level of the tones at each microphone increases with increasing angle of attack for inboard-down propeller rotation and decreases for inboard-up rotation. The level also increases with increasing slideslip angle for both propeller directions of rotation. Increasing the power coefficient results in a slight increase in the level of the tones. A strong shock wave is generated by the propeller blades even at relatively low helical tip Mach numbers resulting in high harmonic levels. As the helical tip Mach number and the advance ratio are increased, the level of the higher harmonics increases much faster than the level of the blade passage frequency.

  16. Validated Feasibility Study of Integrally Stiffened Metallic Fuselage Panels for Reducing Manufacturing Costs

    NASA Technical Reports Server (NTRS)

    Pettit, R. G.; Wang, J. J.; Toh, C.

    2000-01-01

    The continual need to reduce airframe cost and the emergence of high speed machining and other manufacturing technologies has brought about a renewed interest in large-scale integral structures for aircraft applications. Applications have been inhibited, however, because of the need to demonstrate damage tolerance, and by cost and manufacturing risks associated with the size and complexity of the parts. The Integral Airframe Structures (IAS) Program identified a feasible integrally stiffened fuselage concept and evaluated performance and manufacturing cost compared to conventional designs. An integral skin/stiffener concept was produced both by plate hog-out and near-net extrusion. Alloys evaluated included 7050-T7451 plate, 7050-T74511 extrusion, 6013-T6511 extrusion, and 7475-T7351 plate. Mechanical properties, structural details, and joint performance were evaluated as well as repair, static compression, and two-bay crack residual strength panels. Crack turning behavior was characterized through panel tests and improved methods for predicting crack turning were developed. Manufacturing cost was evaluated using COSTRAN. A hybrid design, made from high-speed machined extruded frames that are mechanically fastened to high-speed machined plate skin/stringer panels, was identified as the most cost-effective manufacturing solution. Recurring labor and material costs of the hybrid design are up to 61 percent less than the current technology baseline.

  17. An analytic modeling and system identification study of rotor/fuselage dynamics at hover

    NASA Technical Reports Server (NTRS)

    Hong, Steven W.; Curtiss, H. C., Jr.

    1993-01-01

    A combination of analytic modeling and system identification methods have been used to develop an improved dynamic model describing the response of articulated rotor helicopters to control inputs. A high-order linearized model of coupled rotor/body dynamics including flap and lag degrees of freedom and inflow dynamics with literal coefficients is compared to flight test data from single rotor helicopters in the near hover trim condition. The identification problem was formulated using the maximum likelihood function in the time domain. The dynamic model with literal coefficients was used to generate the model states, and the model was parametrized in terms of physical constants of the aircraft rather than the stability derivatives resulting in a significant reduction in the number of quantities to be identified. The likelihood function was optimized using the genetic algorithm approach. This method proved highly effective in producing an estimated model from flight test data which included coupled fuselage/rotor dynamics. Using this approach it has been shown that blade flexibility is a significant contributing factor to the discrepancies between theory and experiment shown in previous studies. Addition of flexible modes, properly incorporating the constraint due to the lag dampers, results in excellent agreement between flight test and theory, especially in the high frequency range.

  18. Cost model relationships between textile manufacturing processes and design details for transport fuselage elements

    NASA Technical Reports Server (NTRS)

    Metschan, Stephen L.; Wilden, Kurtis S.; Sharpless, Garrett C.; Andelman, Rich M.

    1993-01-01

    Textile manufacturing processes offer potential cost and weight advantages over traditional composite materials and processes for transport fuselage elements. In the current study, design cost modeling relationships between textile processes and element design details were developed. Such relationships are expected to help future aircraft designers to make timely decisions on the effect of design details and overall configurations on textile fabrication costs. The fundamental advantage of a design cost model is to insure that the element design is cost effective for the intended process. Trade studies on the effects of processing parameters also help to optimize the manufacturing steps for a particular structural element. Two methods of analyzing design detail/process cost relationships developed for the design cost model were pursued in the current study. The first makes use of existing databases and alternative cost modeling methods (e.g. detailed estimating). The second compares design cost model predictions with data collected during the fabrication of seven foot circumferential frames for ATCAS crown test panels. The process used in this case involves 2D dry braiding and resin transfer molding of curved 'J' cross section frame members having design details characteristic of the baseline ATCAS crown design.

  19. Auto Mechanics I. Learning Activity Packets (LAPs). Section C--Engine.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains five learning activity packets (LAPs) that outline the study activities for the "engine" instructional area for an Auto Mechanics I course. The five LAPs cover the following topics: basic engine principles, cooling system, engine lubrication system, exhaust system, and fuel system. Each LAP contains a cover sheet that…

  20. Auto Mechanics I. Learning Activity Packets (LAPs). Section B--Measuring.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains three learning activity packets (LAPs) that outline the study activities for the instructional area of measuring for an Auto Mechanics I course. The three LAPs cover the following topics: rules, the outside micrometer, and the inside micrometer. Each LAP contains a cover sheet that describes its purpose, an introduction, and…

  1. Auto Mechanics I. Learning Activity Packets (LAPs). Section D--Suspension.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains six learning activity packets (LAPs) that outline the study activities for the "suspension" instructional area for an Auto Mechanics I course. The six LAPs cover the following topics: wheel bearings, tires and wheels, wheel balancing, suspension system, steering system, and wheel alignment. Each LAP contains a cover sheet…

  2. Effects of aircraft noise on flight and ground structures

    NASA Technical Reports Server (NTRS)

    Mixson, J. S.; Mayes, W. H.; Willis, C. M.

    1976-01-01

    Acoustic loads measured on jet-powered STOL configurations are presented for externally blown and upper surface blown flap models ranging in size from a small laboratory model up to a full-scale aircraft model. The implications of the measured loads for potential acoustic fatigue and cabin noise are discussed. Noise transmission characteristics of light aircraft structures are presented. The relative importance of noise transmission paths, such as fuselage sidewall and primary structure, is estimated. Acceleration responses of a historic building and a residential home are presented for flyover noise from subsonic and supersonic aircraft. Possible effects on occupant comfort are assessed. The results from these three examples show that aircraft noise can induce structural responses that are large enough to require consideration in the design or operation of the aircraft.

  3. Propeller aircraft interior noise model utilization study and validation

    NASA Technical Reports Server (NTRS)

    Pope, L. D.

    1984-01-01

    Utilization and validation of a computer program designed for aircraft interior noise prediction is considered. The program, entitled PAIN (an acronym for Propeller Aircraft Interior Noise), permits (in theory) predictions of sound levels inside propeller driven aircraft arising from sidewall transmission. The objective of the work reported was to determine the practicality of making predictions for various airplanes and the extent of the program's capabilities. The ultimate purpose was to discern the quality of predictions for tonal levels inside an aircraft occurring at the propeller blade passage frequency and its harmonics. The effort involved three tasks: (1) program validation through comparisons of predictions with scale-model test results; (2) development of utilization schemes for large (full scale) fuselages; and (3) validation through comparisons of predictions with measurements taken in flight tests on a turboprop aircraft. Findings should enable future users of the program to efficiently undertake and correctly interpret predictions.

  4. Propeller aircraft interior noise model utilization study and validation

    NASA Astrophysics Data System (ADS)

    Pope, L. D.

    1984-09-01

    Utilization and validation of a computer program designed for aircraft interior noise prediction is considered. The program, entitled PAIN (an acronym for Propeller Aircraft Interior Noise), permits (in theory) predictions of sound levels inside propeller driven aircraft arising from sidewall transmission. The objective of the work reported was to determine the practicality of making predictions for various airplanes and the extent of the program's capabilities. The ultimate purpose was to discern the quality of predictions for tonal levels inside an aircraft occurring at the propeller blade passage frequency and its harmonics. The effort involved three tasks: (1) program validation through comparisons of predictions with scale-model test results; (2) development of utilization schemes for large (full scale) fuselages; and (3) validation through comparisons of predictions with measurements taken in flight tests on a turboprop aircraft. Findings should enable future users of the program to efficiently undertake and correctly interpret predictions.

  5. Progress Towards Fuselage Drag Reduction via Active Flow Control: A Combined CFD and Experimental Effort

    NASA Technical Reports Server (NTRS)

    Schaefler, Norman W.; Allan, Brian G.; Lienard, Caroline; LePape, Arnaud

    2010-01-01

    A combined computational and experimental effort has been undertaken to study fuselage drag reduction on a generic, non-proprietary rotorcraft fuselage by the application of active ow control. Fuselage drag reduction is an area of research interest to both the United States and France and this area is being worked collaboratively as a task under the United States/France Memorandum of Agreement on Helicopter Aeromechanics. In the first half of this task, emphasis is placed on the US generic fuselage, the ROBIN-mod7, with the experimental work being conducted on the US side and complementary US and French CFD analysis of the baseline and controlled cases. Fuselage simulations were made using Reynolds-averaged Navier-Stokes ow solvers and with multiple turbulence models. Comparisons were made to experimental data for numerical simulations of the isolated fuselage and for the fuselage as installed in the tunnel, which includes modeling of the tunnel contraction, walls, and support fairing. The numerical simulations show that comparisons to the experimental data are in good agreement when the tunnel and model support are included. The isolated fuselage simulations compare well to each other, however, there is a positive shift in the centerline pressure when compared to the experiment. The computed flow separation locations on the rear ramp region had only slight differences with and without the tunnel walls and model support. For the simulations, the flow control slots were placed at several locations around the flow separation lines as a series of eight slots that formed a nearly continuous U-shape. Results from the numerical simulations resulted in an estimated 35% fuselage drag reduction from a steady blowing flow control configuration and a 26% drag reduction for unsteady zero-net-mass flow control configuration. Simulations with steady blowing show a delayed flow separation at the rear ramp of the fuselage that increases the surface pressure acting on the ramp

  6. Closeup view of the aft fuselage of the Orbiter Discovery ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up view of the aft fuselage of the Orbiter Discovery on the starboard side looking forward. This view is of the attach surface for the Orbiter Maneuvering System/Reaction Control System (OMS/RCS) Pod. The OMS/RCS pods are removed for processing and reconditioning at another facility. This view was taken from a service platform in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  7. Probabilistic evaluation of fuselage-type composite structures

    NASA Technical Reports Server (NTRS)

    Shiao, Michael C.; Chamis, Christos C.

    1992-01-01

    A methodology is developed to computationally simulate the uncertain behavior of composite structures. The uncertain behavior includes buckling loads, natural frequencies, displacements, stress/strain etc., which are the consequences of the random variation (scatter) of the primitive (independent random) variables in the constituent, ply, laminate and structural levels. This methodology is implemented in the IPACS (Integrated Probabilistic Assessment of Composite Structures) computer code. A fuselage-type composite structure is analyzed to demonstrate the code's capability. The probability distribution functions of the buckling loads, natural frequency, displacement, strain and stress are computed. The sensitivity of each primitive (independent random) variable to a given structural response is also identified from the analyses.

  8. Closeup view of the aft fuselage looking forward along the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up view of the aft fuselage looking forward along the approximate centerline of the Orbiter Discovery looking at the expansion nozzles of the Space Shuttle Main Engines (SSME) and the Orbiter Maneuvering System. Also in the view is the orbiter's body flap with a protective covering over the High-temperature Reusable Surface Insulation tiles on the surface facing the SSMEs. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  9. Closeup view of the underside of the forward fuselage of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up view of the underside of the forward fuselage of the Orbiter Discovery looking at the nose landing-gear and into the landing-gear well. The vehicle is elevated and supported by jack stands attached to the hoist attach points and the rear External Tank attach points on the propellant disconnect plate assemblies. This photo was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  10. Boeing-747 aircraft with external cargo pod

    NASA Technical Reports Server (NTRS)

    Quartero, C. B.; Washburn, G. F.; Price, J. E.

    1978-01-01

    An analysis was conducted to investigate the feasibility of mounting a detachable pod to the underside of the fuselage of a Boeing Model 747 aircraft to carry outsized cargo in case of military emergency. The analysis showed that the 747 configured with the pod and carrying only a bridge launcher as payload attained a range of 8.70 Mm (4 700 n. mi.) at Mach .68. This range was based on a maximum take-off gross weight of 3.447 MN (775 000 1bf) which included 212 kN (47 700 lbf) pod weight and 543 kN (122 000 lbf) payload (bridge launcher).

  11. Design Document: Content Module; L.A.P. Version I.

    ERIC Educational Resources Information Center

    Porch, Ann; Lang, Pat

    A series of computer programs and routines designed to assist researchers in the analysis of language usage was developed by the Southwest Regional Laboratory (SWRL). This document is one of a series that describes design specifications for the individual modules which comprise the Language Analysis Package (LAP). The Content Module functions as a…

  12. Learning Activity Package, Physical Science 92, LAPs 1-9.

    ERIC Educational Resources Information Center

    Williams, G. J.

    This set of nine teacher-prepared Learning Activity Packages (LAPs) for individualized instruction in physical science covers the topics of scientific equipment and procedures; measure of time, length, area, and volume; water; oxygen and oxidation; atmospheric pressure; motion; machines; carbon; and light and sound. Each unit contains a rationale…

  13. Insights: A LAP on Moles: Teaching an Important Concept.

    ERIC Educational Resources Information Center

    Ihde, John

    1985-01-01

    Describes a learning activity packet (LAP) designed to help students understand the basic concept of the mole as a chemical unit; know relationships between the mole and atomic weights in the periodic table; and solve basic conversion problems involving moles, atoms, and molecules. (JN)

  14. Learning Activity Package, Algebra 124, LAPs 46-55.

    ERIC Educational Resources Information Center

    Holland, Bill

    A series of 10 teacher-prepared Learning Activity Packages (LAPs) in advanced algebra and trigonometry, these units cover absolute value, inequalities, exponents, radicals, and complex numbers; functions; higher degree equations and the derivative; the trigonometric functions; graphs and applications of the trigonometric functions; sequences and…

  15. Aircraft wing structure detail design

    NASA Technical Reports Server (NTRS)

    Sager, Garrett L.; Roberts, Ron; Mallon, Bob; Alameri, Mohamed; Steinbach, Bill

    1993-01-01

    The provisions of this project call for the design of the structure of the wing and carry-through structure for the Viper primary trainer, which is to be certified as a utility category trainer under FAR part 23. The specific items to be designed in this statement of work were Front Spar, Rear Spar, Aileron Structure, Wing Skin, and Fuselage Carry-through Structure. In the design of these parts, provisions for the fuel system, electrical system, and control routing were required. Also, the total weight of the entire wing planform could not exceed 216 lbs. Since this aircraft is to be used as a primary trainer, and the SOW requires a useful life of 107 cycles, it was decided that all of the principle stresses in the structural members would be kept below 10 ksi. The only drawback to this approach is a weight penalty.

  16. Algebraic grid generation about wing-fuselage bodies

    NASA Technical Reports Server (NTRS)

    Smith, R. E.

    1986-01-01

    An algebraic procedure for the generation of boundary-fitted grids about wing-fuselage configurations is presented. A wing-fuselage configuration is specified by cross sections and mathematically represented by Coons' patches. A configuration is divided into sections so that several grid blocks that either adjoin each other or partially overlap each other can be generated. Each grid has six exterior surfaces that map into a computational cube. Grids are first determined on the six boundary surfaces and then in the interior. Grid curves that are on the surface of the configuration are derived from the intersection of planes with the Coons' patch definition. Single-valued functions relating approximate arc lengths along the grid curves to a computational coordinate define the distribution of grid points. The two-boundary technique and transfinite interpolation are used to determine the boundary surface grids that are not on the configuration, and transfinite interpolation with linear blending functions is used to determine the interior grid.

  17. Numerical Investigation of a Fuselage Boundary Layer Ingestion Propulsion Concept

    NASA Technical Reports Server (NTRS)

    Elmiligui, Alaa A.; Fredericks, William J.; Guynn, Mark D.; Campbell, Richard L.

    2013-01-01

    In the present study, a numerical assessment of the performance of fuselage boundary layer ingestion (BLI) propulsion techniques was conducted. This study is an initial investigation into coupling the aerodynamics of the fuselage with a BLI propulsion system to determine if there is sufficient potential to warrant further investigation of this concept. Numerical simulations of flow around baseline, Boundary Layer Controlled (BLC), and propelled boundary layer controlled airships were performed. Computed results showed good agreement with wind tunnel data and previous numerical studies. Numerical simulations and sensitivity analysis were then conducted on four BLI configurations. The two design variables selected for the parametric study of the new configurations were the inlet area and the inlet to exit area ratio. Current results show that BLI propulsors may offer power savings of up to 85% over the baseline configuration. These interim results include the simplifying assumption that inlet ram drag is negligible and therefore likely overstate the reduction in power. It has been found that inlet ram drag is not negligible and should be included in future analysis.

  18. Local design optimization for composite transport fuselage crown panels

    NASA Technical Reports Server (NTRS)

    Swanson, G. D.; Ilcewicz, L. B.; Walker, T. H.; Graesser, D.; Tuttle, M.; Zabinsky, Z.

    1992-01-01

    Composite transport fuselage crown panel design and manufacturing plans were optimized to have projected cost and weight savings of 18 and 45 percent, respectively. These savings are close to those quoted as overall NASA Advanced Composite Technology (ACT) program goals. Three local optimization tasks were found to influence the cost and weight of fuselage crown panels. The effects are summarized of each task and the task associated with a design cost model is described in detail. Studies were performed to evaluate the relationship between manufacturing cost and design details. A design tool was developed to aid in these studies. The development of the design tool included combining cost and performance constraints with a random search optimization algorithm. The resulting software was used in a series of optimization studies that evaluated the sensitivity of design variables, guidelines, criteria, and material selection on cost. The effect of blending adjacent design points in a full scale panel subjected to changing load distributions and local variations was shown to be important. Technical issues and directions for future work were identified.

  19. Local design optimization for composite transport fuselage crown panels

    NASA Technical Reports Server (NTRS)

    Swanson, G. D.; Ilcewicz, L. B.; Walker, T. H.; Graesser, D.; Tuttle, M.; Zabinsky, Z.

    1992-01-01

    Composite transport fuselage crown panel design and manufacturing plans were optimized to have projected cost and weight savings of 18 percent and 45 percent, respectively. These savings are close to those quoted as overall NASA ACT program goals. Three local optimization tasks were found to influence the cost and weight of fuselage crown panels. This paper summarizes the effect of each task and describes in detail the task associated with a design cost model. Studies were performed to evaluate the relationship between manufacturing cost and design details. A design tool was developed to aid in these investigations. The development of the design tool included combining cost and performance constraints with a random search optimization algorithm. The resulting software was used in a series of optimization studies that evaluated the sensitivity of design variables, guidelines, criteria, and material selection on cost. The effect of blending adjacent design points in a full scale panel subjected to changing load distributions and local variations was shown to be important. Technical issues and directions for future work were identified.

  20. Study on utilization of advanced composites in fuselage structures of large transports

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.; Thomson, L. W.; Wilson, R. D.

    1985-01-01

    The potential for utilizing advanced composites in fuselage structures of large transports was assessed. Six fuselage design concepts were selected and evaluated in terms of structural performance, weight, and manufacturing development and costs. Two concepts were selected that merit further consideration for composite fuselage application. These concepts are: (1) a full depth honeycomb design with no stringers, and (2) an I section stringer stiffened laminate skin design. Weight reductions due to applying composites to the fuselages of commercial and military transports were calculated. The benefits of applying composites to a fleet of military transports were determined. Significant technology issues pertinent to composite fuselage structures were identified and evaluated. Program plans for resolving the technology issues were developed.

  1. Correlation of AH-1G airframe flight vibration data with a coupled rotor-fuselage analysis

    NASA Technical Reports Server (NTRS)

    Sangha, K.; Shamie, J.

    1990-01-01

    The formulation and features of the Rotor-Airframe Comprehensive Analysis Program (RACAP) is described. The analysis employs a frequency domain, transfer matrix approach for the blade structural model, a time domain wake or momentum theory aerodynamic model, and impedance matching for rotor-fuselage coupling. The analysis is applied to the AH-1G helicopter, and a correlation study is conducted on fuselage vibration predictions. The purpose of the study is to evaluate the state-of-the-art in helicopter fuselage vibration prediction technology. The fuselage vibration predicted using RACAP are fairly good in the vertical direction and somewhat deficient in the lateral/longitudinal directions. Some of these deficiencies are traced to the fuselage finite element model.

  2. Control of an all-movable foreplane for a three surfaces aircraft wind tunnel model

    NASA Astrophysics Data System (ADS)

    Ricci, S.; Scotti, A.; Zanotti, D.

    2006-07-01

    This article deals with design and realisation of a canard foreplane control system for an aeroelastic demonstrator, suitable for wind tunnel testing. Hardware and software will be described as the methodology adopted to design, implement and realise the software. Specific attention is devoted to PID application, tuning and fuselage vibration control implementation. Results of preliminary test and simulations are presented and show realistic system effectiveness in damping fuselage bending and torsion. This work describes all the activity performed at Politecnico di Milano before wind tunnel testing at VZLU, Prague, as part of Active Aeroelastic Aircraft Structures (3AS) EU project.

  3. Propeller aircraft interior noise model: User's manual for computer program

    NASA Astrophysics Data System (ADS)

    Wilby, E. G.; Pope, L. D.

    1985-01-01

    A computer program entitled PAIN (Propeller Aircraft Interior Noise) has been developed to permit calculation of the sound levels in the cabin of a propeller-driven airplane. The fuselage is modeled as a cylinder with a structurally integral floor, the cabin sidewall and floor being stiffened by ring frames, stringers and floor beams of arbitrary configurations. The cabin interior is covered with acoustic treatment and trim. The propeller noise consists of a series of tones at harmonics of the blade passage frequency. Input data required by the program include the mechanical and acoustical properties of the fuselage structure and sidewall trim. Also, the precise propeller noise signature must be defined on a grid that lies in the fuselage skin. The propeller data are generated with a propeller noise prediction program such as the NASA Langley ANOPP program. The program PAIN permits the calculation of the space-average interior sound levels for the first ten harmonics of a propeller rotating alongside the fuselage. User instructions for PAIN are given in the report. Development of the analytical model is presented in NASA CR 3813.

  4. The mechanics and tribology of fretting fatigue with application to riveted lap joints

    NASA Astrophysics Data System (ADS)

    Szolwinski, Matthew Paul

    Fretting is the synergistic combination of wear, corrosion, and fatigue damage mechanisms driven by the partial slip of contacting surfaces. The surface microslip and near-surface contact stresses associated with fretting can lead to severe reduction in service lifetimes of contacting components as diversified as bearings, turbine blades and mechanically-fastened joints, both structural and biological. This tribologically induced degradation has come under close scrutiny by those responsible for maintaining aging fleets of both commercial and military aircraft. Thus a critical need exists for predicting fretting crack nucleation in riveted aluminum. aircraft joints. Fulfilling this need requires characterizing both the near-surface mechanics and intimately-related tribology of fretting. To this end, a well characterized experimental setup has been developed to generate carefully controlled and monitored fretting contacts to investigate the nature of the near-surface conditions. Included in this investigation were in-situ observations of the fretting contact stress field via a non-invasive thermal imaging technique and a characterization of the evolution of friction under partial slip conditions. With specific qualitative and quantitative understanding of these near-surface conditions, a series of fretting fatigue experiments have been conducted to validate a mechanics-based model for predicting fretting fatigue crack nucleation. Finally, efforts have been directed toward extending this understanding of fretting crack nucleation to riveted aircraft structure through modeling of the riveting process and a related experimental program designed to link riveting process parameters and fretting damage in single-lap joint structures. This work focuses specifically on determination of the residual stresses induced during rivet installation and the morphological characterization of fretting fatigue damage in the riveted test specimens manufactured under controlled

  5. Aircraft interior noise reduction by alternate resonance tuning

    NASA Technical Reports Server (NTRS)

    Bliss, Donald B.; Gottwald, James A.; Gustaveson, Mark B.; Burton, James R., III; Castellino, Craig

    1989-01-01

    Existing interior noise reduction techniques for aircraft fuselages perform reasonably well at higher frequencies, but are inadequate at lower, particularly with respect to the low blade passage harmonics with high forcing levels found in propeller aircraft. A method is being studied which considers aircraft fuselages lines with panels alternately tuned to frequencies above and below the frequency to be attenuated. Adjacent panels would oscillate at equal amplitude, to give equal source strength, but with opposite phase. Provided these adjacent panels are acoustically compact, the resulting cancellation causes the interior acoustic modes to become cut off and therefore be non-propagating and evanescent. This interior noise reduction method, called Alternate Resonance Tuning (ART), is currently being investigated both theoretically and experimentally. This new concept has potential application to reducing interior noise due to the propellers in advanced turboprop aircraft as well as for existing aircraft configurations. This program summarizes the work carried out at Duke University during the third semester of a contract supported by the Structural Acoustics Branch at NASA Langley Research Center.

  6. Structural Features of the Pseudomonas fluorescens Biofilm Adhesin LapA Required for LapG-Dependent Cleavage, Biofilm Formation, and Cell Surface Localization

    PubMed Central

    Boyd, Chelsea D.; Smith, T. Jarrod; El-Kirat-Chatel, Sofiane; Newell, Peter D.; Dufrêne, Yves F.

    2014-01-01

    The localization of the LapA protein to the cell surface is a key step required by Pseudomonas fluorescens Pf0-1 to irreversibly attach to a surface and form a biofilm. LapA is a member of a diverse family of predicted bacterial adhesins, and although lacking a high degree of sequence similarity, family members do share common predicted domains. Here, using mutational analysis, we determine the significance of each domain feature of LapA in relation to its export and localization to the cell surface and function in biofilm formation. Our previous work showed that the N terminus of LapA is required for cleavage by the periplasmic cysteine protease LapG and release of the adhesin from the cell surface under conditions unfavorable for biofilm formation. We define an additional critical region of the N terminus of LapA required for LapG proteolysis. Furthermore, our results suggest that the domains within the C terminus of LapA are not absolutely required for biofilm formation, export, or localization to the cell surface, with the exception of the type I secretion signal, which is required for LapA export and cell surface localization. In contrast, deletion of the central repetitive region of LapA, consisting of 37 repeats of 100 amino acids, results in an inability to form a biofilm. We also used single-molecule atomic force microscopy to further characterize the role of these domains in biofilm formation on hydrophobic and hydrophilic surfaces. These studies represent the first detailed analysis of the domains of the LapA family of biofilm adhesin proteins. PMID:24837291

  7. Consideration of some factors affecting low-frequency fuselage noise transmission for propeller aircraft

    NASA Technical Reports Server (NTRS)

    Mixson, J. S.; Roussos, L. A.

    1986-01-01

    Possible reasons for disagreement between measured and predicted trends of sidewall noise transmission at low frequency are investigated using simplified analysis methods. An analytical model combining incident plane acoustic waves with an infinite flat panel is used to study the effects of sound incidence angle, plate structural properties, frequency, absorption, and the difference between noise reduction and transmission loss. Analysis shows that these factors have significant effects on noise transmission but they do not account for the differences between measured and predicted trends at low frequencies. An analytical model combining an infinite flat plate with a normally incident acoustic wave having exponentially decaying magnitude along one coordinate is used to study the effect of a localized source distribution such as is associated with propeller noise. Results show that the localization brings the predicted low-frequency trend of noise transmission into better agreement with measured propeller results. This effect is independent of low-frequency stiffness effects that have been previously reported to be associated with boundary conditions.

  8. Full-scale flammability test data for validation of aircraft fire mathematical models

    NASA Technical Reports Server (NTRS)

    Kuminecz, J. F.; Bricker, R. W.

    1982-01-01

    Twenty-five large scale aircraft flammability tests were conducted in a Boeing 737 fuselage at the NASA Johnson Space Center (JSC). The objective of this test program was to provide a data base on the propagation of large scale aircraft fires to support the validation of aircraft fire mathematical models. Variables in the test program included cabin volume, amount of fuel, fuel pan area, fire location, airflow rate, and cabin materials. A number of tests were conducted with jet A-1 fuel only, while others were conducted with various Boeing 747 type cabin materials. These included urethane foam seats, passenger service units, stowage bins, and wall and ceiling panels. Two tests were also included using special urethane foam and polyimide foam seats. Tests were conducted with each cabin material individually, with various combinations of these materials, and finally, with all materials in the cabin. The data include information obtained from approximately 160 locations inside the fuselage.

  9. Aerodynamics of powered missile separation from F/A-18 aircraft

    NASA Technical Reports Server (NTRS)

    Ahmad, J. U.; Shanks, S. P.; Buning, P. G.

    1993-01-01

    A 3D dynamic 'chimera' algorithm that solves the thin-layer Navier-Stokes equations over multiple moving bodies was modified to numerically simulate the aerodynamics, missile dynamics, and missile plume interactions of a missile separating from a generic wing and from an F/A-18 aircraft in transonic flow. The missile is mounted below the wing for missile separation from the wing and on the F/A-18 fuselage at the engine inlet side for missile separation from aircraft. Static and powered missile separation cases are considered to examine the influence of the missile and plume on the wing and F/A-18 fuselage and engine inlet. The aircraft and missile are at two degrees angle of attack, Reynolds number of 10 million, freestream Mach number of 1.05 and plume Mach number of 3.0. The computational results show the details of the flow field.

  10. Interior noise control prediction study for high-speed propeller-driven aircraft

    NASA Technical Reports Server (NTRS)

    Rennison, D. C.; Wilby, J. F.; Marsh, A. H.; Wilby, E. G.

    1979-01-01

    An analytical model was developed to predict the noise levels inside propeller-driven aircraft during cruise at M = 0.8. The model was applied to three study aircraft with fuselages of different size (wide body, narrow body and small diameter) in order to determine the noise reductions required to achieve the goal of an A-weighted sound level which does not exceed 80 dB. The model was then used to determine noise control methods which could achieve the required noise reductions. Two classes of noise control treatments were investigated: add-on treatments which can be added to existing structures, and advanced concepts which would require changes to the fuselage primary structure. Only one treatment, a double wall with limp panel, provided the required noise reductions. Weight penalties associated with the treatment were estimated for the three study aircraft.

  11. Life determination of riveted aircraft structure by holographic NDE

    NASA Astrophysics Data System (ADS)

    Baird, John P.; Heslehurst, Rikard B.; Williamson, Hugh M.; Clark, Robert K.; Hollamby, Derek

    1996-11-01

    In a project funded by the Federal Aviation Administration's (FAA) Aging Aircraft Program, a Portable Holographic Inspection System (PHITS) has been further developed. The technique involves taking a double exposure white light reflection hologram of aircraft structures. Each exposure is taken at a slightly different load state, and the resulting interferogram shows the deformations that occur between the two load states. Results showed that the rivets in a simple lap joint, designed to simulate the longitudinal lap splice on a Boeing 737, behaved in two distinct and easily recognizable modes. The first mode occurred at low loads and was an indication that friction forces between the two sheets of the lap joint dominated the load transfer mechanism. Indications were that the second mode related to higher loads for which the friction forces played a much lesser role. The load at which the changeover begins to occur has been called the critical load. Preliminary experiments showed that structures with a high value of critical load had a fatigue life of order ten times that of a normally fastened splice. Critical load can be readily determined in the field using the PHITS system. Research designed to establish the relationship between fatigue life and critical load is continuing. An understanding of that relationship could lead to a technique capable of fatigue life determination in typical aircraft structures.

  12. Material characterization of structural adhesives in the lap shear mode

    NASA Technical Reports Server (NTRS)

    Sancaktar, E.; Schenck, S. C.

    1983-01-01

    A general method for characterizing structual adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semiempirical and theoretical approaches are used. The semiempirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Two different model adhesives are used in the single lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.

  13. FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY

    SciTech Connect

    Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

    2007-01-09

    Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

  14. The impact of lubricants on the precision lapping process.

    PubMed

    Jiang, Xionghua; Chen, Zhenxing; Wolfram, Joy; Wei, Zhongxian; Shen, Yuqiu; Yang, Zhizhou

    2014-12-01

    The impact of lubricants on pole-tip recession and surface morphology of hard disk drive heads in the precision lapping process was investigated with atomic force microscopy, scanning electron microscopy, and auger electron spectroscopy. In particular, the effects of deionized water, hydrocarbon oil, ethanediol, isopropanol, and ethanol lubricants were evaluated. The results reveal that proper selection of lubricant is critical for achieving optimal performance in the lapping process. A mixture of 68% hydrocarbon oil, 30% isopropanol, and 2% octadecenoic acid was found to yield the most favorable results, displaying a writer shield recession, first shield of reader recession, and surface roughness of 0.423, 0.581, and 0.242 nm, respectively. PMID:25387606

  15. Identification of bolted lap joints parameters in assembled structures

    NASA Astrophysics Data System (ADS)

    Ahmadian, Hamid; Jalali, Hassan

    2007-02-01

    Bolted lap joints have significant influence on the dynamical behaviour of the assembled structures due to creation of strong local flexibility and damping. In modelling the dynamical behaviour of assembled structures the joint interface model must be represented accurately. A nonlinear model for bolted lap joints and interfaces is proposed capable of representing the dominant physics involved in the joint such as micro/macro-slip. The joint interface is modelled using a combination of linear and nonlinear springs and a damper to simulate the damping effects of the joint. An estimate of the response of the structure with a nonlinear model for the bolted joint under external excitations is obtained using the method of multiple scales. The parameters of the model, i.e. the spring constants and the damper coefficient, are functions of normal and tangential stresses at the joint interface and are identified by minimizing the difference between the model predictions and the experimentally measured data.

  16. Distribution of Acoustic Power Spectra for an Isolated Helicopter Fuselage

    NASA Astrophysics Data System (ADS)

    Kusyumov, A. N.; Mikhailov, S. A.; Garipova, L. I.; Batrakov, A. S.; Barakos, G.

    2016-03-01

    The broadband aerodynamic noise can be studied, assuming isotropic flow, turbulence and decay. Proudman's approach allows practical calculations of noise based on CFD solutions of RANS or URANS equations at the stage of post processing and analysis of the solution. Another aspect is the broadband acoustic spectrum and the distribution of acoustic power over a range of frequencies. The acoustic energy spectrum distribution in isotropic turbulence is non monotonic and has a maximum at a certain value of Strouhal number. In the present work the value of acoustic power peak frequency is determined using a prescribed form of acoustic energy spectrum distribution presented in papers by S. Sarkar and M. Y. Hussaini and by G. M. Lilley. CFD modelling of the flow around isolated helicopter fuselage model was considered using the HMB CFD code and the RANS equations.

  17. Closeup oblique view of the aft fuselage of the Orbiter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and port as the last Space Shuttle Main Engine is being removed, it can be seen on the left side of the image frame. Note that one of the Orbiter Maneuvering System/ Reaction Control System has been removed while one of them remains. Also note that the body flap, below the engine positions has a protective covering to prevent damage to the High-temperature Reusable Surface Insulation tiles. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  18. Closeup oblique view of the aft fuselage of the Orbiter ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and starboard as the last Space Shuttle Main Engine is being removed, it can be seen on the right side of the image frame. Note that one of the Orbiter Maneuvering System/ Reaction Control System has been removed while one of them remains. Also note that the body flap, below the engine positions has a protective covering to prevent damage to the High-temperature Reusable Surface Insulation tiles. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  19. Interior noise considerations for powered-lift STOL aircraft

    NASA Technical Reports Server (NTRS)

    Barton, C. K.

    1975-01-01

    Powered-lift configurations which are currently under development for future use on STOL aircraft involve impingement of the jet engine exhaust onto wing and flap surfaces. Previous studies have suggested that the impinging jet produces higher noise levels at lower frequencies than does the jet alone. These higher levels, together with the close proximity of the engine and flap noise sources to the fuselage sidewall, suggest that the noise levels in these aircraft may be high enough to interfere with passenger comfort. To investigate this possibility, interior noise levels were estimated for both an upper surface blown (USB) and an externally blown flap (EBF) configuration. This paper describes the procedure used to estimate the interior noise levels and compares these levels with levels on existing jet aircraft and on ground transportation vehicles. These estimates indicate high levels in the STOL aircraft; therefore, areas of possible improvements in technology for control of STOL interior noise are also discussed.

  20. An overview of the crash dynamics failure behavior of metal and composite aircraft structures

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.; Boitnott, Richard L.; Fasanella, Edwin L.; Jones, Lisa E.

    1991-01-01

    An overview of failure behavior results is presented from some of the crash dynamics research conducted with concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. Experimental and analytical data are presented that indicate some general trends in the failure behavior of a class of composite structures that includes fuselage panels, individual fuselage sections, fuselage frames, skeleton subfloors with stringers and floor beams without skin covering, and subfloors with skin added to the frame stringer structure. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models.

  1. Aircraft propeller induced structure-borne noise

    NASA Technical Reports Server (NTRS)

    Unruh, James F.

    1989-01-01

    A laboratory-based test apparatus employing components typical of aircraft construction was developed that would allow the study of structure-borne noise transmission due to propeller induced wake/vortex excitation of in-wake structural appendages. The test apparatus was employed to evaluate several aircraft installation effects (power plant placement, engine/nacelle mass loading, and wing/fuselage attachment methods) and several structural response modifications for structure-borne noise control (the use of wing blocking mass/fuel, wing damping treaments, and tuned mechanical dampers). Most important was the development of in-flight structure-borne noise transmission detection techniques using a combination of ground-based frequency response function testing and in-flight structural response measurement. Propeller wake/vortex excitation simulation techniques for improved ground-based testing were also developed to support the in-flight structure-borne noise transmission detection development.

  2. Method of vibration isolating an aircraft engine

    NASA Technical Reports Server (NTRS)

    Bender, Stanley I. (Inventor); Butler, Lawrence (Inventor); Dawes, Peter W. (Inventor)

    1991-01-01

    A method for coupling an engine to a support frame for mounting to a fuselage of an aircraft using a three point vibration isolating mounting system in which the load reactive forces at each mounting point are statically and dynamically determined. A first vibration isolating mount pivotably couples a first end of an elongated support beam to a stator portion of an engine with the pivoting action of the vibration mount being oriented such that it is pivotable about a line parallel to a center line of the engine. An aft end of the supporting frame is coupled to the engine through an additional pair of vibration isolating mounts with the mounts being oriented such that they are pivotable about a circumference of the engine. The aft mounts are symmetrically spaced to each side of the supporting frame by 45 degrees. The relative orientation between the front mount and the pair of rear mounts is such that only the rear mounts provide load reactive forces parallel to the engine center line, in support of the engine to the aircraft against thrust forces. The forward mount is oriented so as to provide only radial forces to the engine and some lifting forces to maintain the engine in position adjacent a fuselage. Since each mount is connected to provide specific forces to support the engine, forces required of each mount are statically and dynamically determinable.

  3. Measurement of aircraft speed and altitude

    NASA Technical Reports Server (NTRS)

    Gracey, W.

    1980-01-01

    Problems involved in measuring speed and altitude with pressure-actuated instruments (altimeter, airspeed indicator, true-airspeed indicator, Machmeter, and vertical-speed indicator) are examined. Equations relating total pressure and static pressure to the five flight quantities are presented, and criteria for the design of total and static pressure tubes are given. Calibrations of typical static pressure installations (fuselage nose, wing tip, vertical fin, and fuselage vent) are presented, various methods for flight calibration of these installations are described, and the calibration of a particular installation by two of the methods is described in detail. Equations are given for estimating the effects of pressure lag and leaks. Test procedures for the laboratory calibration of the five instruments are described, and accuracies of mechanical and electrical instruments are presented. Operational use of the altimeter for terrain clearance and vertical separation of aircraft is discussed, along with flight technical errors and overall altitude errors of aircraft in cruise operations. Altitude-measuring techniques based on a variety of properties of the Earth and the atmosphere are included. Two appendixes present airspeed and altitude tables and sample calculations for determining the various flight parameters from measured total and static pressures.

  4. Investigation into Interface Lifting Within FSW Lap Welds

    SciTech Connect

    K. S. Miller; C. R. Tolle; D. E. Clark; C. I. Nichol; T. R. McJunkin; H. B. Smartt

    2008-06-01

    Friction stir welding (FSW) is rapidly penetrating the welding market in many materials and applications, particularly in aluminum alloys for transportation applications. As this expansion outside the research laboratory continues, fitness for service issues will arise, and process control and NDE methods will become important determinants of continued growth. The present paper describes research into FSW weld nugget flaw detection within aluminum alloy lap welds. We present results for two types of FSW tool designs: a smooth pin tool and a threaded pin tool. We show that under certain process parameters (as monitored during welding with a rotating dynamometer that measures x, y, z, and torque forces) and tooling designs, FSW lap welds allow significant nonbonded interface lifting of the lap joint, while forming a metallurgical bond only within the pin region of the weld nugget. These lifted joints are often held very tightly together even though unbonded, and might be expected to pass cursory NDE while representing a substantial compromise in joint mechanical properties. The phenomenon is investigated here via radiographic and ultrasonic NDE techniques, with a copper foil marking insert (as described elsewhere) and by the tensile testing of joints. As one would expect, these results show that tool design and process parameters significantly affect plactic flow and this lifted interface. NDE and mechanical strength ramifications of this defect are discussed.

  5. Residual Strength Analyses of Riveted Lap-Splice Joints

    NASA Technical Reports Server (NTRS)

    Seshadri, B. R.; Newman, J. C., Jr.

    2000-01-01

    The objective of this paper was to analyze the crack-linkup behavior in riveted-stiffened lap-splice joint panels with small multiple-site damage (MSD) cracks at several adjacent rivet holes. Analyses are based on the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. To account for high constraint around a crack front, the "plane strain core" option in STAGS was used. The importance of modeling rivet flexibility with fastener elements that accurately model load transfer across the joint is discussed. Fastener holes are not modeled but rivet connectivity is accounted for by attaching rivets to the sheet on one side of the cracks that simulated both the rivet diameter and MSD cracks. Residual strength analyses made on 2024-T3 alloy (1.6-mm thick) riveted-lap-splice joints with a lead crack and various size MSD cracks were compared with test data from Boeing Airplane Company. Analyses were conducted for both restrained and unrestrained buckling conditions. Comparison of results from these analyses and results from lap-splice-joint test panels, which were partially restrained against buckling indicate that the test results were bounded by the failure loads predicted by the analyses with restrained and unrestrained conditions.

  6. Aircraft accident report: NASA 712, Convair 990, N712NA, March Air Force Base, California, July 17, 1985, executive summary

    NASA Technical Reports Server (NTRS)

    Batthauer, Byron E.; Mccarthy, G. T.; Hannah, Michael; Hogan, Robert J.; Marlow, Frank J.; Reynard, William D.; Stoklosa, Janis H.; Yager, Thomas J.

    1986-01-01

    On July 17, l985, NASA 712, a Convair 990 aircraft, was destroyed by fire during an aborted takeoff at March Air Force Base in California. Material ejected from a blowout in the tires of the right main landing gear penetrated the right-wing fuel tank. The leaking fuel ignited. Fire engulfed the right wing and fuselage as the aircraft stopped its forward motion. The crew of four and the 15 scientists and technicians aboard escaped without serious injury.

  7. On the prediction of auto-rotational characteristics of light airplane fuselages

    NASA Technical Reports Server (NTRS)

    Pamadi, B. N.; Taylor, L. W., Jr.

    1984-01-01

    A semi-empirical theory is presented for the estimation of aerodynamic forces and moments acting on a steadily rotating (spinning) airplane fuselage, with a particular emphasis on the prediction of its auto-rotational behavior. This approach is based on an extension of the available analytical methods for high angle of attack and side-slip and then coupling this procedure with strip theory for application to a rotating airplane fuselage. The analysis is applied to the fuselage of a light general aviation airplane and the results are shown to be in fair agreement with experimental data.

  8. Design of a spanloader cargo aircraft

    NASA Technical Reports Server (NTRS)

    1989-01-01

    With a growing demand for fast international freight service, the slow-moving cargo ships currently in use will soon find a substantial portion of their clients looking elsewhere. One candidate for filling this expected gap in the freight market is a span-loading aircraft (or 'flying wing') capable of long-range operation with extremely large payloads. This report summarizes the design features of an aircraft capable of fulfilling a long-haul, high-capacity cargo mission. The spanloader seeks to gain advantage over conventional aircraft by eliminating the aircraft fuselage and thus reducing empty weight. The primary disadvantage of this configuration is that the cargo-containing wing tends to be thick, thus posing a challenge to the airfoil designer. It also suffers from stability and control problems not encountered by conventional aircraft. The result is an interesting, challenging exercise in unconventional design. The report that follows is a student written synopsis of an effort judged to be the best of eight designs developed during the year 1988-1989.

  9. Optimal tubular adhesive-bonded lap joint of the carbon fiber epoxy composite shaft

    NASA Astrophysics Data System (ADS)

    Kim, Ki S.; Kim, Won T.; Lee, Dai G.; Jun, Eui J.

    The effects of the adhesive thickness and the adherend surface roughness on the fatigue strength of a tubular adhesive-bonded single lap joint were investigated using fatigue test specimens whose adherends were made of S45C carbon steel. Results of fatigue tests showed that the optimal arithmetic surface roughness of the adherends is about 2 microns and the optimal adhesive thickness is about 0.15 mm. Using these values, the prototype torsional adhesive joints were manufactured for power transmission shafts of an automotive vehicle or a small helicopter, and static tests under torque were performed on a single-lap joint, a single-lap joint with scarf, a double-lap joint, and a double-lap joint with scarf. It was found that the double-lap joint was superior among the joints, in terms of torque capacity and manufacturing cost.

  10. Guanidine-phosphate non-covalent interaction in LAP crystal growth solution evidenced from spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Wang, L.; Zhang, G. H.; Wang, X. Q.; Zhu, L. Y.; Xu, D.

    2015-09-01

    The similar L-arginine molecule aggregation has been found in L-arginine (LA) and L-arginine phosphate monohydrate (LAP) aqueous solutions. The special fluorescence emission at 380 nm of LA aggregates in LAP solution has been found, compared with the emission of LA solution at 415 nm, which has an obvious blue shift. By comparing the fluorescence spectra of several solutions for L-arginine and L-lysine salts, the interaction between phosphate and guanidine in LAP solution was considered to be the cause of its special fluorescence emission. Meanwhile, when LAP molecule formed in solution, the fluorescence emission wavelength and the UV absorption intensity at 296 nm of L-arginine solutions have mutated. Therefore, the group interaction involved by guanidine has changed the fluorescence properties of L-arginine aggregates in LAP solution, indicating that the specific interaction between phosphate and guanidine exists in LAP molecule.

  11. Rolling flow wind tunnel tests of F-18 aircraft

    NASA Technical Reports Server (NTRS)

    Lutze, F. H.

    1980-01-01

    The lateral directional characteristics of an F-18 aircraft was investigated. Aerodynamic derivatives associated with pure roll rate, or the 'p' derivatives were obtained. The model is described and the procedures used to obtain and correct the data, and a graphical presentation of the results are presented. These results include graphs of the lateral directional static stability derivatives versus angle of attack, and the lateral directional force and moment coefficients versus nondimensional roll rate. Results are presented for several configurations including complete, complete without vertical tails, complete without horizontal tails, fuselage wing and fuselage alone. Each of these configuations was tested with and without wing leading edge extensions. The basic control surfaces were deflected and the results were investigated.

  12. Curved flow wind tunnnel test of F-18 aircraft

    NASA Technical Reports Server (NTRS)

    Lutze, F. H.

    1980-01-01

    The curved flow capability of a stability wind tunnel was used to investigate the lateral directional characteristics of an F-18 aircraft. The model is described and the procedures used to obtain and correct the data and a graphical presentation of the results are presented. The results include graphs of lateral directional derivatives versus sideslip or static plots, the lateral directional static stability derivatives versus angle of attack, and finally the lateral directional derivatives versus nondimensional yaw rate for different angles of attack and sideslip. Results are presented for several configurations including complete, complete without vertical tails, complete without horizontal tails, fuselage wing and fuselage alone. Each of these were tested with and without wing leading edge extensions.

  13. Payload specialists Baudry and Chretien in the Shuttle full fuselage trainer

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Payload specialists Patrick Baudry (left) and Jean Loup Chretien are seated at the commander and pilot stations on the Shuttle full fuselage trainer. In this view they are looking at the camera over the backs of the shuttle seats.

  14. STS 51-E crew is briefed on the Shuttle full fuselage trainer

    NASA Technical Reports Server (NTRS)

    1984-01-01

    STS 51-E crew is briefed on the Shuttle full fuselage trainer. Astronauts Dave Griggs (foreground), Jean Loup Chretien (behind Griggs) and Jeff Hoffman are being shown the workings of the trainer by flight instructors.

  15. Coupled rotor-flexible fuselage vibration reduction using open loop higher harmonic control

    NASA Technical Reports Server (NTRS)

    Papavassiliou, I.; Friedmann, P. P.; Venkatesan, C.

    1991-01-01

    A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computer facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselae vibrations a new scheme called multiple higher harmonic control is required.

  16. Evaluation of Pressurization Fatigue Life of 1441 Al-li Fuselage Panel

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Dicus, Dennis I.; Fridlyander, Joseph; Davydov, Valentin

    1999-01-01

    A study was conducted to evaluate the pressurization fatigue life of fuselage panels with skins fabricated from 1441 Al-Li, an attractive new Russian alloy. The study indicated that 1441 Al-Li has several advantages over conventional aluminum fuselage skin alloy with respect to fatigue behavior. Smooth 1441 Al-Li sheet specimens exhibited a fatigue endurance limit similar to that for 1163 Al (Russian version of 2024 Al) sheet. Notched 1441 Al-Li sheet specimens exhibited greater fatigue strength and longer fatigue life than 1163 Al. In addition, Tu-204 fuselage panels fabricated by Tupolev Design Bureau using Al-Li skin and ring frames with riveted 7000-series aluminum stiffeners had longer pressurization fatigue lives than did panels constructed from conventional aluminum alloys. Taking into account the lower density of this alloy, the results suggest that 1441 Al-Li has the potential to improve fuselage performance while decreasing structural weight.

  17. Aircraft Design

    NASA Technical Reports Server (NTRS)

    Bowers, Albion H. (Inventor); Uden, Edward (Inventor)

    2016-01-01

    The present invention is an aircraft wing design that creates a bell shaped span load, which results in a negative induced drag (induced thrust) on the outer portion of the wing; such a design obviates the need for rudder control of an aircraft.

  18. Aircraft Noise

    NASA Astrophysics Data System (ADS)

    Michel, Ulf; Dobrzynski, Werner; Splettstoesser, Wolf; Delfs, Jan; Isermann, Ullrich; Obermeier, Frank

    Aircraft industry is exposed to increasing public pressure aiming at a continuing reduction of aircraft noise levels. This is necessary to both compensate for the detrimental effect on noise of the expected increase in air traffic and improve the quality of living in residential areas around airports.

  19. Vertical drop test of a transport fuselage section located forward of the wing

    NASA Technical Reports Server (NTRS)

    Williams, M. S.; Hayduk, R. J.

    1983-01-01

    A Boeing 707 fuselage section was drop tested at the NASA Langley Research Center to measure structural, seat, and occupant response to vertical crack loads. Post-test inspection showed that the section bottom collapsed inward approximately 2 ft. Preliminary data traces indicated maximum normal accelerations of 20 g on the fuselage bottom, 10 to 12 g on the cabin floor, and 6.5 to 8 g in the pelvises of the anthropomorphic dummies.

  20. Low-Speed Aerodynamic Characteristics of a Fuselage Model with Various Arrangements of Elongated Lift Jets

    NASA Technical Reports Server (NTRS)

    Vogler, R. D.; Goodson, K. W.

    1973-01-01

    Data were obtained for a round jet located on the center of the bottom of a fuselage and for elongated slots separated spanwise by distances of 0.8 and 1.2 of the fuselage width. The effect of yawing the slots, inclining the jets laterally, and combining slot yaw with jet inclination was determined. Data were obtained in and out of ground effect through a range of effective velocity ratios and through a range of sideslip angles.

  1. Development of Textile Reinforced Composites for Aircraft Structures

    NASA Technical Reports Server (NTRS)

    Dexter, H. Benson

    1998-01-01

    NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980's NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not cost-effective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight service with minimal damage. The cost and damage tolerance barriers of conventional laminated composites led NASA to focus on new concepts in composites which would incorporate the automated manufacturing methods of the textiles industry and which would incorporate through-the-thickness reinforcements. The NASA Advanced Composites Technology (ACT) Program provided the resources to extensively investigate the application of textile processes to next generation aircraft wing and fuselage structures. This paper discusses advanced textile material forms that have been developed, innovative machine concepts and key technology advancements required for future application of textile reinforced composites in commercial transport aircraft. Multiaxial warp knitting, triaxial braiding and through-the-thickness stitching are the three textile processes that have surfaced as the most promising for further development. Textile reinforced composite structural elements that have been developed in the NASA ACT Program are discussed. Included are braided fuselage frames and window-belt reinforcements, woven/stitched lower fuselage side panels, stitched multiaxial warp knit wing skins, and braided wing stiffeners. In addition, low-cost processing concepts such as resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM) are discussed. Process modeling concepts to predict resin flow and cure in textile preforms are also discussed.

  2. Flying qualities and control system characteristics for superaugmented aircraft

    NASA Technical Reports Server (NTRS)

    Myers, T. T.; Mcruer, D. T.; Johnston, D. E.

    1984-01-01

    Aircraft-alone dynamics and superaugmented control system fundamental regulatory properties including stability and regulatory responses of the basic closed-loop systems; fundamental high and low frequency margins and governing factors; and sensitivity to aircraft and controller parameters are addressed. Alternative FCS mechanizations, and mechanizational side effects are also discussed. An overview of flying qualities considerations encompasses general pilot operations as a controller in unattended, intermittent and trim, and full-attention regulatory or command control; effective vehicle primary and secondary response properties to pilot inputs and disturbances; pilot control architectural possibilities; and comparison of superaugmented and conventional aircraft path responses for different forms of pilot control. Results of a simple experimental investigation into pilot dynamic behavior in attitude control of superaugmented aircraft configurations with high frequency time laps and time delays are presented.

  3. Active Aerodynamic Load Reduction on a Rotorcraft Fuselage With Rotor Effects: A CFD Validation Effort

    NASA Technical Reports Server (NTRS)

    Allan, Brian G.; Schaeffler, Norman W.; Jenkins, Luther N.; Yao, Chung-Sheng; Wong, Oliver D.; Tanner, Philip E.

    2015-01-01

    A rotorcraft fuselage is typically designed with an emphasis on operational functionality with aerodynamic efficiency being of secondary importance. This results in a significant amount of drag during high-speed forward flight that can be a limiting factor for future high-speed rotorcraft designs. To enable higher speed flight, while maintaining a functional fuselage design (i.e., a large rear cargo ramp door), the NASA Rotary Wing Project has conducted both experimental and computational investigations to assess active flow control as an enabling technology for fuselage drag reduction. This paper will evaluate numerical simulations of a flow control system on a generic rotorcraft fuselage with a rotor in forward flight using OVERFLOW, a structured mesh Reynolds-averaged Navier-Stokes flow solver developed at NASA. The results are compared to fuselage forces, surface pressures, and PN flow field data obtained in a wind tunnel experiment conducted at the NASA Langley 14-by 22-Foot Subsonic Tunnel where significant drag and download reductions were demonstrated using flow control. This comparison showed that the Reynolds-averaged Navier-Stokes flow solver was unable to predict the fuselage forces and pressure measurements on the ramp for the baseline and flow control cases. While the CFD was able to capture the flow features, it was unable to accurately predict the performance of the flow control.

  4. Numerical solutions for heat flow in adhesive lap joints

    NASA Technical Reports Server (NTRS)

    Howell, P. A.; Winfree, William P.

    1992-01-01

    The present formulation for the modeling of heat transfer in thin, adhesively bonded lap joints precludes difficulties associated with large aspect ratio grids required by standard FEM formulations. This quasi-static formulation also reduces the problem dimensionality (by one), thereby minimizing computational requirements. The solutions obtained are found to be in good agreement with both analytical solutions and solutions from standard FEM programs. The approach is noted to yield a more accurate representation of heat-flux changes between layers due to a disbond.

  5. Parameter studies on impact in a lap joint

    NASA Astrophysics Data System (ADS)

    Rahmani, Amir M.; Ervin, Elizabeth K.

    2015-03-01

    To represent a loose lap joint, a beam impacting four springs with gaps is modeled. Modal analysis with base excitation is solved, and time histories of contact points are closely monitored. Using the impulse during steady state response, six influential parameters are studied: damping ratio, contact stiffness, intermediate contact position, gap, excitation amplitude and beam height. For all parameters, the system response is highly controlled by modes with two contacting springs. Each parameter's effect on system response is presented including unstable regions, unique trend behaviours result. Recommendations for structural designers are also noted.

  6. Interference drag in a simulated wing-fuselage juncture

    NASA Technical Reports Server (NTRS)

    Kubendran, L. R.; Mcmahon, H.; Hubbartt, J. E.

    1984-01-01

    The interference drag in a wing fuselage juncture as simulated by a flat plate and a body of constant thickness having a 1.5:1 elliptical leading edge is evaluated experimentally. The experimental measurements consist of mean velocity data taken with a hot wire at a streamwise location corresponding to 16 body widths downstream of the body leading edge. From these data, the interference drag is determined by calculating the total momentum deficit (momentum area) in the juncture and also in the two dimensional turbulent boundary layers on the flat plate and body at locations sufficiently far from the juncture flow effect. The interference drag caused by the juncture drag as measured at this particular streamwise station is -3% of the total drag due to the flat plate and body boundary layers in isolation. If the body is considered to be a wing having a chord and span equal to 16 body widths, the interference drag due to the juncture is only -1% of the frictional drag of one surface of such a wing.

  7. In situ processing methods for composite fuselage sandwich structures

    NASA Technical Reports Server (NTRS)

    Saatchi, Hossein; Durako, Bill; Reynolds, Dick; Dost, Ernest; Willden, Kurtis

    1993-01-01

    Conventional sandwich structure fabrication methods are labor intensive and high in cost. A low cost method is needed to produce lightweight sandwich structures. Sundstrand has developed a series of in situ composite fabrication methods in which the raw materials (skin and core materials) are placed in a closed mold, and the component is produced in one heating cycle. Internal pressure is generated by chemical agents during the thermal cycles, which consolidates the skins and produces the foam core. The finished part is a net-shape composite sandwich structure with skins and a foamed core. The in situ process reduces cost by eliminating several secondary operations that are used in conventional fabrication methods. Further, a strong molecular bond is produced between the core and skin, which eliminates adhesive bonding and prevents a weak bond section in the sandwich structure. In this investigation, we evaluated the feasibility of the in situ process using thermoset materials currently under consideration for commercial airplane fuselage applications, such as keel sections. The materials used were Hercules 855340 toughened epoxy resin in both liquid and powder forms, and 3M Scotchply PR500 resin, manufactured by 3M Corporation, in powder form. We successfully foamed these resins and produced experimental panels with AS-4/855340 Hercules prepreg skins. Chopped fibers were added to the core to increase performance of the foam. Mechanical property testing on these panels showed properties competitive with other foams. Additional experiments are required to optimize the in situ foam core sandwiches for specific properties and applications.

  8. Closeup view of the aft fuselage of the Orbiter Discovery ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Close-up view of the aft fuselage of the Orbiter Discovery looking at the thrust structure that supports the Space Shuttle Main Engines (SSMEs). In this view, SSME number two position is on the left and SSME number three position is on the right. The thrust structure transfers the forces produce by the engines into and through the airframe of the orbiter. The thrust structure includes the SSMEs load reaction truss structure, engine interface fittings and the hydraulic-actuator support structure. The propellant feed lines are the plugged and capped orifices within the engine bays. Note that SSME position two is rotated ninety degrees from position three and one. This was needed to enable enough clearance for the engines to fit and gimbal. Note in engine bay three is a clear view of the actuators that control the gambling of that engine. This view was taken from a service platform in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  9. Fatigue life until small cracks in aircraft structures: Durability and damage tolerance

    NASA Technical Reports Server (NTRS)

    Schijve, J.

    1994-01-01

    Crack initiation in notched elements occurs very early in the fatigue life. This is also true for riveted lap joints, an important fatigue critical element of a pressurized fuselage structure. Crack nucleation in a riveted lap joint can occur at different locations, depending on the riveting operation. It can occur at the edge of the rivet hole, at a small distance away from the hole, but still with subsequent crack growth through the hole, and ahead of the hole with a crack no longer passing through the hole. Moreover, crack nucleation can occur in the top row at the countersunk holes (outer sheet) or in the bottom row at the non-countersunk holes. Fractographic evidence is shown. The initial growth of the small cracks occurs as an (invisible) part through crack. As a consequence, predictions on the crack initiation life are problematic. After a though crack is present, the major part of the fatigue life has been consumed. There is still an apparent lack of empirical data on crack growth and residual strength of riveted lap joints, five years after the Aloha accident. Such data are very much necessary for further developments of prediction models. Some test results are presented.

  10. Evaluation of the influence of aircraft shielding on the aircrew exposure through an aircraft mathematical model.

    PubMed

    Ferrari, A; Pelliccioni, M; Villari, R

    2004-01-01

    In order to investigate the influence of aircraft shielding on the galactic component of cosmic rays, an aircraft mathematical model has been developed by the combinatorial geometry package of the Monte-Carlo transport code FLUKA. The isotropic irradiation of the aircraft in the cosmic ray environment has been simulated. Effective dose and ambient dose equivalent rates have been determined inside the aircraft at several locations along the fuselage, at a typical civil aviation altitude (10 580 m), for vertical cut-off rigidity of 0.4 GV (poles) and 17.6 GV (equator) and deceleration potential of 465 MV. The values of both quantities were generally lower than those in the free atmosphere. They depend, in an intricate manner, on the location within the aircraft, quantity of fuel, number of passengers, etc. The position onboard of crew members should be taken into account when assessing individual doses. Likewise due consideration must be taken when positioning detectors which are used to measure H*(10). Care would be needed to avoid ambiguity when comparing the results of calculation with the experimental data. PMID:14978289

  11. Machine Shop I. Learning Activity Packets (LAPs). Section B--Basic and Related Technology.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains eight learning activity packets (LAPs) for the "basic and related technology" instructional area of a Machine Shop I course. The eight LAPs cover the following topics: basic mathematics, blueprints, rules, micrometer measuring tools, Vernier measuring tools, dial indicators, gaging and inspection tools, and materials and…

  12. Learning Activity Package, Biology 102, (LAP) Studies 1, 3, and 4.

    ERIC Educational Resources Information Center

    Rhoden, Bruce

    Included are three Learning Activity Package (LAP) studies for use in high school biology: Everything has a Place (Grouping and the Diversity of Life), Energy Relations, and Reproduction. Each LAP contains a rationale for teaching the material included, student objectives (stated in behavioral terms), a list of related resources (books,…

  13. Improvement of transformer core magnetic properties using the step-lap design

    NASA Astrophysics Data System (ADS)

    Valkovic, Z.; Rezic, A.

    1992-07-01

    Magnetic properties of the step-lap joints have been investigated experimentally on two three-phase three-leg transformer cores. Using the step-lap joint design, a reduction of the total core loss of 2 to 4.4% and of the exciting power of 31 to 37% has been obtained.

  14. Auto Mechanics I. Learning Activity Packets (LAPs). Section A--Orientation and Safety.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains seven learning activity packets (LAPs) that outline the study activities for the orientation and safety instructional area for an Auto Mechanics I course. The seven LAPs cover the following topics: orientation, safety, hand tools, arc welding, oxyacetylene cutting, oxyacetylene fusion welding, and oxyacetylene braze welding.…

  15. Structural Integrity Evaluation of the Lear Fan 2100 Aircraft

    NASA Technical Reports Server (NTRS)

    Kan, H. P.; Dyer, T. A.

    1996-01-01

    An in-situ nondestructive inspection was conducted to detect manufacturing and assembly induced defects in the upper two wing surfaces (skin s) and upper fuselage skin of the Lear Fan 2100 aircraft E009. The effects of the defects, detected during the inspection, on the integrity of the structure was analytically evaluated. A systematic evaluation was also conducted to determine the damage tolerance capability of the upper wing skin against impact threats and assembly induced damage. The upper wing skin was divided into small regions for damage tolerance evaluations. Structural reliability, margin of safety, allowable strains, and allowable damage size were computed. The results indicated that the impact damage threat imposed on composite military aircraft structures is too severe for the Lear Fan 2100 upper wing skin. However, the structural integrity is not significantly degraded by the assembly induced damage for properly assembled structures, such as the E009 aircraft.

  16. QCGAT aircraft/engine design for reduced noise and emissions

    NASA Technical Reports Server (NTRS)

    Lanson, L.; Terrill, K. M.

    1980-01-01

    The high bypass ratio QCGAT engine played an important role in shaping the aircraft design. The aircraft which evolved is a sleek, advanced design, six-place aircraft with 3538 kg (7,800 lb) maximum gross weight. It offers a 2778 kilometer (1500 nautical mile) range with cruise speed of 0.5 Mach number and will take-off and land on the vast majority of general aviation airfields. Advanced features include broad application of composite materials and a supercritical wing design with winglets. Full-span fowler flaps were introduced to improve landing capability. Engines are fuselage-mounted with inlets over the wing to provide shielding of fan noise by the wing surfaces. The design objectives, noise, and emission considerations, engine cycle and engine description are discussed as well as specific design features.

  17. Diagnostics and Active Control of Aircraft Interior Noise

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1998-01-01

    This project deals with developing advanced methods for investigating and controlling interior noise in aircraft. The work concentrates on developing and applying the techniques of Near Field Acoustic Holography (NAH) and Principal Component Analysis (PCA) to the aircraft interior noise dynamic problem. This involves investigating the current state of the art, developing new techniques and then applying them to the particular problem being studied. The knowledge gained under the first part of the project was then used to develop and apply new, advanced noise control techniques for reducing interior noise. A new fully active control approach based on the PCA was developed and implemented on a test cylinder. Finally an active-passive approach based on tunable vibration absorbers was to be developed and analytically applied to a range of test structures from simple plates to aircraft fuselages.

  18. Ultrasonic guided wave inspection of Inconel 625 brazed lap joints

    NASA Astrophysics Data System (ADS)

    Comot, Pierre; Bocher, Philippe; Belanger, Pierre

    2016-04-01

    The aerospace industry has been investigating the use of brazing for structural joints, as a mean of reducing cost and weight. There therefore is a need for a rapid, robust, and cost-effective non-destructive testing method for evaluating the structural integrity of the joints. The mechanical strength of brazed joints depends mainly on the amount of brittle phases in their microstructure. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. Moreover, they offer the opportunity to inspect complex shape joints. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the amount of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint.

  19. Lap Shear Testing of Candidate Radiator Panel Adhesives

    NASA Technical Reports Server (NTRS)

    Ellis, David; Briggs, Maxwell; McGowan, Randy

    2013-01-01

    During testing of a subscale radiator section used to develop manufacturing techniques for a full-scale radiator panel, the adhesive bonds between the titanium heat pipes and the aluminum face sheets failed during installation and operation. Analysis revealed that the thermal expansion mismatch between the two metals resulted in relatively large shear stresses being developed even when operating the radiator at moderate temperatures. Lap shear testing of the adhesive used in the original joints demonstrated that the two-part epoxy adhesive fell far short of the strength required. A literature review resulted in several candidate adhesives being selected for lap shear joint testing at room temperature and 398 K, the nominal radiator operating temperature. The results showed that two-part epoxies cured at room and elevated temperatures generally did not perform well. Epoxy film adhesives cured at elevated temperatures, on the other hand, did very well with most being sufficiently strong to cause yielding in the titanium sheet used for the joints. The use of an epoxy primer generally improved the strength of the joint. Based upon these results, a new adhesive was selected for the second subscale radiator section.

  20. Nonlinear Analysis of Bonded Composite Single-LAP Joints

    NASA Technical Reports Server (NTRS)

    Oterkus, E.; Barut, A.; Madenci, E.; Smeltzer, S. S.; Ambur, D. R.

    2004-01-01

    This study presents a semi-analytical solution method to analyze the geometrically nonlinear response of bonded composite single-lap joints with tapered adherend edges under uniaxial tension. The solution method provides the transverse shear and normal stresses in the adhesive and in-plane stress resultants and bending moments in the adherends. The method utilizes the principle of virtual work in conjunction with von Karman s nonlinear plate theory to model the adherends and the shear lag model to represent the kinematics of the thin adhesive layer between the adherends. Furthermore, the method accounts for the bilinear elastic material behavior of the adhesive while maintaining a linear stress-strain relationship in the adherends. In order to account for the stiffness changes due to thickness variation of the adherends along the tapered edges, their in-plane and bending stiffness matrices are varied as a function of thickness along the tapered region. The combination of these complexities results in a system of nonlinear governing equilibrium equations. This approach represents a computationally efficient alternative to finite element method. Comparisons are made with corresponding results obtained from finite-element analysis. The results confirm the validity of the solution method. The numerical results present the effects of taper angle, adherend overlap length, and the bilinear adhesive material on the stress fields in the adherends, as well as the adhesive, of a single-lap joint

  1. Generic element formulation for modelling bolted lap joints

    NASA Astrophysics Data System (ADS)

    Ahmadian, Hamid; Jalali, Hassan

    2007-07-01

    Joints have significant effects on the dynamic response of the assembled structures due to existence of two non-linear mechanisms in their interface, namely slipping and slapping. These mechanisms affect the structural response by adding considerable damping into the structure and lowering the natural frequencies due to the stiffness softening. Neglecting these effects in modelling of joints produces errors in predictions of the structure responses. In this paper, a non-linear generic element formulation is developed for modelling bolted lap joints. The generic element is formed by satisfying all conditions that are known for a joint interface and hence providing a non-linear parametric formulation for the families of allowable joint models. Dynamic response of the developed model for the assembled structure including the generic joint interface element is obtained using the incremental harmonic balance (IHB) method. The generic parameters of the joint are identified by minimising the difference between the model response obtained from IHB method and the observed behaviour of the structure. The procedure is demonstrated by modelling an actual structure containing a single lap bolted joint in the middle. The frequency responses of the structure around the first two resonance frequencies are measured by exciting the structure using a sinusoidal force at each individual frequency. The measured responses are compared with the predictions of the model containing a parametric generic joint element. The parameters of the joint interface model are successfully identified by minimising the difference between the measured responses and the model predictions.

  2. Edge effect modeling and experiments on active lap processing.

    PubMed

    Liu, Haitao; Wu, Fan; Zeng, Zhige; Fan, Bin; Wan, Yongjian

    2014-05-01

    Edge effect is regarded as one of the most difficult technical issues for fabricating large primary mirrors, especially for large polishing tools. Computer controlled active lap (CCAL) uses a large size pad (e.g., 1/3 to 1/5 workpiece diameters) to grind and polish the primary mirror. Edge effect also exists in the CCAL process in our previous fabrication. In this paper the material removal rules when edge effects happen (i.e. edge tool influence functions (TIFs)) are obtained through experiments, which are carried out on a Φ1090-mm circular flat mirror with a 375-mm-diameter lap. Two methods are proposed to model the edge TIFs for CCAL. One is adopting the pressure distribution which is calculated based on the finite element analysis method. The other is building up a parametric equivalent pressure model to fit the removed material curve directly. Experimental results show that these two methods both effectively model the edge TIF of CCAL. PMID:24921777

  3. Evaluation of structural design concepts for an arrow-wing supersonic cruise aircraft

    NASA Technical Reports Server (NTRS)

    Sakata, I. F.; Davis, G. W.

    1977-01-01

    An analytical study was performed to determine the best structural approach for design of primary wing and fuselage structure of a Mach 2.7 arrow wing supersonic cruise aircraft. Concepts were evaluated considering near term start of design. Emphasis was placed on the complex interactions between thermal stress, static aeroelasticity, flutter, fatigue and fail safe design, static and dynamic loads, and the effects of variations in structural arrangements, concepts and materials on these interactions. Results indicate that a hybrid wing structure incorporating low profile convex beaded and honeycomb sandwich surface panels of titanium alloy 6Al-4V were the most efficient. The substructure includes titanium alloy spar caps reinforced with boron polyimide composites. The fuselage shell consists of hat stiffened skin and frame construction of titanium alloy 6Al-4V. A summary of the study effort is presented, and a discussion of the overall logic, design philosophy and interaction between the analytical methods for supersonic cruise aircraft design are included.

  4. Aircraft Wing for Over-The-Wing Mounting of Engine Nacelle

    NASA Technical Reports Server (NTRS)

    Hahn, Andrew S. (Inventor); Kinney, David J. (Inventor)

    2011-01-01

    An aircraft wing has an inboard section and an outboard section. The inboard section is attached (i) on one side thereof to the aircraft's fuselage, and (ii) on an opposing side thereof to an inboard side of a turbofan engine nacelle in an over-the-wing mounting position. The outboard section's leading edge has a sweep of at least 20 degrees. The inboard section's leading edge has a sweep between -15 and +15 degrees, and extends from the fuselage to an attachment position on the nacelle that is forward of an index position defined as an imaginary intersection between the sweep of the outboard section's leading edge and the inboard side of the nacelle. In an alternate embodiment, the turbofan engine nacelle is replaced with an open rotor engine nacelle.

  5. Flow visualization studies of VTOL aircraft models during Hover in ground effect

    NASA Technical Reports Server (NTRS)

    Mourtos, Nikos J.; Couillaud, Stephane; Carter, Dale; Hange, Craig; Wardwell, Doug; Margason, Richard J.

    1995-01-01

    A flow visualization study of several configurations of a jet-powered vertical takeoff and landing (VTOL) aircraft model during hover in ground effect was conducted. A surface oil flow technique was used to observe the flow patterns on the lower surfaces of the model. There were significant configuration effects. Wing height with respect to fuselage, the presence of an engine inlet duct beside the fuselage, and nozzle pressure ratio are seen to have strong effects on the surface flow angles on the lower surface of the wing. This test was part of a program to improve the methods for predicting the hot gas ingestion (HGI) for jet-powered vertical/short takeoff and landing (V/STOL) aircraft. The tests were performed at the Jet Calibration and Hover Test (JCAHT) Facility at Ames Research Center.

  6. Melanin targets LC3-associated phagocytosis (LAP): A novel pathogenetic mechanism in fungal disease.

    PubMed

    Chamilos, Georgios; Akoumianaki, Tonia; Kyrmizi, Irene; Brakhage, Axel; Beauvais, Anne; Latge, Jean-Paul

    2016-05-01

    Intracellular swelling of conidia of the major human airborne fungal pathogen Aspergillus fumigatus results in surface exposure of immunostimulatory pathogen-associated molecular patterns (PAMPs) and triggers activation of a specialized autophagy pathway called LC3-associated phagocytosis (LAP) to promote fungal killing. We have recently discovered that, apart from PAMPs exposure, cell wall melanin removal during germination of A. fumigatus is a prerequisite for activation of LAP. Importantly, melanin promotes fungal pathogenicity via targeting LAP, as a melanin-deficient A. fumigatus mutant restores its virulence upon conditional inactivation of Atg5 in hematopoietic cells of mice. Mechanistically, fungal cell wall melanin selectively excludes the CYBA/p22phox subunit of NADPH oxidase from the phagosome to inhibit LAP, without interfering with signaling regulating cytokine responses. Notably, inhibition of LAP is a general property of melanin pigments, a finding with broad physiological implications. PMID:27028978

  7. Quantitative thermal imaging of aircraft structures

    NASA Astrophysics Data System (ADS)

    Cramer, K. Elliott; Howell, Patricia A.; Syed, Hazari I.

    1995-03-01

    Aircraft structural integrity is a major concern for airlines and airframe manufacturers. To remain economically competitive, airlines are looking at ways to retire older aircraft, not when some fixed number of flight hours or cycles has been reached, but when true structural need dictates. This philosophy is known as `retirement for cause.' The need to extend the life of commercial aircraft has increased the desire to develop nondestructive evaluation (NDE) techniques capable of detecting critical flaws such as disbonding and corrosion. These subsurface flaws are of major concern in bonded lap joints. Disbonding in such a joint can provide an avenue for moisture to enter the structure leading to corrosion. Significant material loss due to corrosion can substantially reduce the structural strength, load bearing capacity and ultimately reduce the life of the structure. The National Aeronautics and Space Administration's Langley Research Center has developed a thermal NDE system designed for application to disbonding and corrosion detection in aircraft skins. By injecting a small amount of heat into the front surface of an aircraft skin, and recording the time history of the resulting surface temperature variations using an infrared camera, quantitative images of both bond integrity and material loss due to corrosion can be produced. This paper presents a discussion of the development of the thermal imaging system as well as the techniques used to analyze the resulting thermal images. The analysis techniques presented represent a significant improvement in the information available over conventional thermal imaging due to the inclusion of data from both the heating and cooling portion of the thermal cycle. Results of laboratory experiments on fabricated disbond and material loss samples are presented to determine the limitations of the system. Additionally, the results of actual aircraft inspections are shown, which help to establish the field applicability for this

  8. The Teacher's Lap--A Site of Emotional Well-Being for the Younger Children in Day-Care Groups

    ERIC Educational Resources Information Center

    Hännikäinen, Maritta

    2015-01-01

    This study focuses on a particular relationship between teachers and one- to three-year-old children: the child in the teacher's lap. When, in what situations, does this happen? Who are the children in the teacher's lap? Why are they there? How do children express emotional well-being when in the teacher's lap? Relational, sociocultural and…

  9. Dechlorination of Chloral Hydrate Is Influenced by the Biofilm Adhesin Protein LapA in Pseudomonas putida LF54

    PubMed Central

    Zhang, Wanjun; Huhe; Pan, Yuanbai; Toyofuku, Masanori; Nomura, Nobuhiko; Nakajima, Toshiaki

    2013-01-01

    LapA is the largest surface adhesion protein of Pseudomonas putida that initiates biofilm formation. Here, by using transposon insertion mutagenesis and a conditional lapA mutant, we demonstrate for the first time that LapA influences chloral hydrate (CH) dechlorination in P. putida LF54. PMID:23603683

  10. Interactive computer graphics system for structural sizing and analysis of aircraft structures

    NASA Technical Reports Server (NTRS)

    Bendavid, D.; Pipano, A.; Raibstein, A.; Somekh, E.

    1975-01-01

    A computerized system for preliminary sizing and analysis of aircraft wing and fuselage structures was described. The system is based upon repeated application of analytical program modules, which are interactively interfaced and sequence-controlled during the iterative design process with the aid of design-oriented graphics software modules. The entire process is initiated and controlled via low-cost interactive graphics terminals driven by a remote computer in a time-sharing mode.

  11. Recent advances in active control of aircraft cabin noise

    NASA Astrophysics Data System (ADS)

    Mathur, Gopal; Fuller, Christopher

    2002-11-01

    Active noise control techniques can provide significant reductions in aircraft interior noise levels without the structural modifications or weight penalties usually associated with passive techniques, particularly for low frequency noise. Our main objective in this presentation is to give a review of active control methods and their applications to aircraft cabin noise reduction with an emphasis on recent advances and challenges facing the noise control engineer in the practical application of these techniques. The active noise control method using secondary acoustic sources, e.g., loudspeakers, as control sources for tonal noise reduction is first discussed with results from an active noise control flight test demonstration. An innovative approach of applying control forces directly to the fuselage structure using piezoelectric actuators, known as active structural acoustic control (ASAC), to control cabin noise is then presented. Experimental results from laboratory ASAC tests conducted on a full-scale fuselage and from flight tests on a helicopter will be discussed. Finally, a hybrid active/passive noise control approach for achieving significant broadband noise reduction will be discussed. Experimental results of control of broadband noise transmission through an aircraft structure will be presented.

  12. Correlation of forebody pressures and aircraft yawing moments on the X-29A aircraft at high angles of attack

    NASA Technical Reports Server (NTRS)

    Fisher, David F.; Richwine, David M.; Landers, Stephen

    1992-01-01

    In-flight pressure distributions at four fuselage stations on the forebody of the X-29A aircraft have been reported at angles of attack from 15 to 66 deg and at Mach numbers from 0.22 to 0.60. At angles of attack of 20 deg and higher, vortices shed from the nose strake caused suction peaks in the pressure distributions that generally increased in magnitude with angle of attack. Above 30 deg-angle of attack, the forebody pressure distributions became asymmetrical at the most forward station, while they remained nearly symmetrical until 50 to 55 deg-angle of attack for the aft stations. Between 59 to 66 deg-angle of attack, the asymmetry of the pressure distributions changed direction. Yawing moments for the forebody alone were obtained by integrating the forebody pressure distributions. At 45 deg-angle of attack, the aircraft yaws to the right and at 50 deg and higher, the aircraft yaws to the left. The forebody yawing moments correlated well with the aircraft left yawing moment at an angle of attack of 50 deg or higher. At a 45 deg-angle of attack, the forebody yawing moments did not correlate well with the aircraft yawing moment, but it is suggested that this was due to asymmetric pressures on the cockpit region of the fuselage which was not instrumented. The forebody was also shown to provide a positive component of directional stability of the aircraft at angles of attack of 25 deg or higher. A Mach number effect was noted at angles of attack of 30 deg or higher at the station where the nose strake was present. At this station, the suction peaks in the pressure distributions at the highest Mach number were reduced and much more symmetrical as compared to the lower Mach number pressure distributions.

  13. The Low-Noise Potential of Distributed Propulsion on a Catamaran Aircraft

    NASA Technical Reports Server (NTRS)

    Posey, Joe W.; Tinetti, A. F.; Dunn, M. H.

    2006-01-01

    The noise shielding potential of an inboard-wing catamaran aircraft when coupled with distributed propulsion is examined. Here, only low-frequency jet noise from mid-wing-mounted engines is considered. Because low frequencies are the most difficult to shield, these calculations put a lower bound on the potential shielding benefit. In this proof-of-concept study, simple physical models are used to describe the 3-D scattering of jet noise by conceptualized catamaran aircraft. The Fast Scattering Code is used to predict noise levels on and about the aircraft. Shielding results are presented for several catamaran type geometries and simple noise source configurations representative of distributed propulsion radiation. Computational analyses are presented that demonstrate the shielding benefits of distributed propulsion and of increasing the width of the inboard wing. Also, sample calculations using the FSC are presented that demonstrate additional noise reduction on the aircraft fuselage by the use of acoustic liners on the inboard wing trailing edge. A full conceptual aircraft design would have to be analyzed over a complete mission to more accurately quantify community noise levels and aircraft performance, but the present shielding calculations show that a large acoustic benefit could be achieved by combining distributed propulsion and liner technology with a twin-fuselage planform.

  14. C/EBPβ-LAP*/LAP Expression Is Mediated by RSK/eIF4B-Dependent Signalling and Boosted by Increased Protein Stability in Models of Monocytic Differentiation

    PubMed Central

    Christmann, Martin; Friesenhagen, Judith; Westphal, Andreas; Pietsch, Daniel; Brand, Korbinian

    2015-01-01

    The transcription factor C/EBPβ plays a key role in monocytic differentiation and inflammation. Its small isoform LIP is associated with proliferation at early premonocytic developmental stages and regulated via mTOR-dependent signalling. During later stages of (pre)monocytic differentiation there is a considerable increase in the large C/EBPβ isoforms LAP*/LAP which inhibit proliferation thus supporting terminal differentiation. Here, we showed in different models of monocytic differentiation that this dramatic increase in the LAP*/LAP protein and LAP/LIP ratio was accompanied by an only modest/retarded mRNA increase suggesting an important role for (post)translational mechanisms. We found that LAP*/LAP formation was induced via MEK/RSK-dependent cascades, whereas mTOR/S6K1 were not involved. Remarkably, LAP*/LAP expression was dependent on phosphorylated eIF4B, an acceleratory protein of RNA helicase eIF4A. PKR inhibition reduced the expression of eIF4B and C/EBPβ in an eIF2α-independent manner. Furthermore, under our conditions a marked stabilisation of LAP*/LAP protein occurred, accompanied by reduced chymotrypsin-like proteasome/calpain activities and increased calpastatin levels. Our study elucidates new signalling pathways inducing LAP*/LAP expression and indicates new alternative PKR functions in monocytes. The switch from mTOR- to RSK-mediated signalling to orchestrate eIF4B-dependent LAP*/LAP translation, accompanied by increased protein stability but only small mRNA changes, may be a prototypical example for the regulation of protein expression during selected processes of differentiation/proliferation. PMID:26646662

  15. Crash tests of four low-wing twin-engine airplanes with truss-reinforced fuselage structure

    NASA Technical Reports Server (NTRS)

    Williams, M. S.; Fasanella, E. L.

    1982-01-01

    Four six-place, low-wing, twin-engine, general aviation airplane test specimens were crash tested under controlled free flight conditions. All airplanes were impacted on a concrete test surface at a nomial flight path velocity of 27 m/sec. Two tests were conducted at a -15 deg flight path angle (0 deg pitch angle and 15 deg pitch angle), and two were conducted at a -30 deg flight path angle (-30 deg pitch angle). The average acceleration time histories (crash pulses) in the cabin area for each principal direction were calculated for each crash test. In addition, the peak floor accelerations were calculated for each test as a function of aircraft fuselage longitudinal station number. Anthropomorphic dummy accelerations were analyzed using the dynamic response index and severity index (SI) models. Parameters affecting the dummy restraint system were studied; these parameters included the effect of no upper torso restraint, measurement of the amount of inertia-reel strap pullout before locking, measurement of dummy chest forward motion, and loads in the restraints. With the SI model, the dummies with no shoulder harness received head impacts above the concussive threshold.

  16. Assessment of Damage Containment Features of a Full-Scale PRSEUS Fuselage Panel Through Test and Teardown

    NASA Technical Reports Server (NTRS)

    Bergan, Andrew C.; Bakuckas, John G., Jr.; Lovejoy, Andrew E.; Jegley, Dawn C.; Awerbuch, Jonathan; Tan, Tein-Min

    2012-01-01

    An area that shows promise in enhancing structural integrity of aircraft and aerospace structures is the integrally stitched composite technology. The most recent generation of this technology is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept developed by Boeing Research and Technology and the National Aeronautics and Space Administration. A joint test program on the assessment of damage containment capabilities of the PRSEUS concept for curved fuselage structures was conducted recently at the Federal Aviation Administration William J. Hughes Technical Center. The panel was subjected to axial tension, internal pressure, and combined axial tension and internal pressure load conditions up to fracture, with a through-the-thickness, two-bay notch severing the central stiffener. For the purpose of future progressive failure analysis development and verification, extensive post failure nondestructive and teardown inspections were conducted. Detailed inspections were performed directly ahead of the notch tip where stable damage progression was observed. These examinations showed: 1) extensive delaminations developed ahead of the notch tip, 2) the extent and location of damage, 3) the typical damage mechanisms observed in composites, and 4) the role of stitching and warp-knitting in the failure mechanisms. The objective of this paper is to provide a summary of results from these posttest inspections.

  17. Use of nose cap and fuselage pressure orifices for determination of air data for space shuttle orbiter below supersonic speeds

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Siemers, P. M., III

    1980-01-01

    Wind tunnel pressure measurements were acquired from orifices on a 0.1 scale forebody model of the space shuttle orbiter that were arranged in a preliminary configuration of the shuttle entry air data system (SEADS). Pressures from those and auxiliary orifices were evaluated for their ability to provide air data at subsonic and transonic speeds. The orifices were on the vehicle's nose cap and on the sides of the forebody forward of the cabin. The investigation covered a Mach number range of 0.25 to 1.40 and an angle of attack range from 4 deg. to 18 deg. An air data system consisting of nose cap and forebody fuselage orifices constitutes a complete and accurate air data system at subsonic and transonic speeds. For Mach numbers less than 0.80 orifices confined to the nose cap can be used as a complete and accurate air data system. Air data systems that use only flush pressure orifices can be used to determine basic air data on other aircraft at subsonic and transonic speeds.

  18. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

    NASA Technical Reports Server (NTRS)

    Bryson, L. L.; Mccarty, J. E.

    1973-01-01

    Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria.

  19. Computational Assessment of the Benefits of Boundary Layer Ingestion for the D8 Aircraft

    NASA Technical Reports Server (NTRS)

    Pandya, Shishir A.; Uranga, Alejandra

    2013-01-01

    To substantially reduce the fuel burn of future commercial transportation aircraft, the boundary layer ingestion idea is investigated. The idea is that an engine placed in the wake of the aircraft it is propelling is more efficient than a conventional engine placement under the wing or on pods mounted to the rear of the fuselage. The top, rear of the fuselage is thus designed to act as a diffuser such that the engines can be placed there with a minimal nacelle. The boundary layer thickens over the rear of the fuselage such that a large portion of it is ingested by the fan. To assess whether the boundary layer ingesting (BLI) engine placement is indeed advantageous, a study of the nacelle aerodynamics is carried out using Overflow, a viscous CFD flow solver that uses overset meshes. The computed forces and moments are compared to a wind tunnel experiment for validation. Some aspects of the design are verified using the simulation results. Finally, the effect of the nacelle placement is assessed by comparing the BLI nacelle configuration to a podded nacelle configuration and to the unpowered (without nacelles) aircraft.

  20. Development of stitched/RTM primary structures for transport aircraft

    NASA Technical Reports Server (NTRS)

    Hawley, Arthur V.

    1993-01-01

    This report covers work accomplished in the Innovative Composite Aircraft Primary Structure (ICAPS) program. An account is given of the design criteria and philosophy that guides the development. Wing and fuselage components used as a baseline for development are described. The major thrust of the program is to achieve a major cost breakthrough through development of stitched dry preforms and resin transfer molding (RTM), and progress on these processes is reported. A full description is provided on the fabrication of the stitched RTM wing panels. Test data are presented.

  1. Computation of Engine Noise Propagation and Scattering Off an Aircraft

    NASA Technical Reports Server (NTRS)

    Xu, J.; Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2003-01-01

    The paper presents a comparison of experimental noise data measured in flight on a two-engine business jet aircraft with Kulite microphones placed on the suction surface of the wing with computational results. Both a time-domain discontinuous Galerkin spectral method and a frequency-domain spectral element method are used to simulate the radiation of the dominant spinning mode from the engine and its reflection and scattering by the fuselage and the wing. Both methods are implemented in computer codes that use the distributed memory model to make use of large parallel architectures. The results show that trends of the noise field are well predicted by both methods.

  2. Study of methane fuel for subsonic transport aircraft

    NASA Technical Reports Server (NTRS)

    Carson, L. K.; Davis, G. W.; Versaw, E. F.; Cunnington, G. R., Jr.; Daniels, E. J.

    1980-01-01

    The cost and performance were defined for commercial transport using liquid methane including its fuel system and the ground facility complex required for the processing and storage of methane. A cost and performance comparison was made with Jet A and hydrogen powered aircraft of the same payload and range capability. Extensive design work was done on cryogenic fuel tanks, insulation systems as well as the fuel system itself. Three candidate fuel tank locations were evaluated, i.e., fuselage tanks, wing tanks or external pylon tanks.

  3. Strain gage installation on the YF-12 aircraft.

    NASA Technical Reports Server (NTRS)

    Wilson, E. J.

    1973-01-01

    A flight-loads measurement program on the YF-12 aircraft required the mounting of 101 strain-gauge bridges in the fuselage, fuel tanks, control surfaces, and three stations on the left wing. The sensors were to be installed primarily on titanium and were required to operate between -70 and +600 F. Strain gauges with modified Karma filaments and backings of glass-fiber reinforced epoxy resin matrices were selected and were installed with an epoxy adhesive. Attention is given to the calibration, mounting, and performance of the sensors in flight-load measurements.

  4. On the way to extended noise reductions in propeller aircraft

    NASA Astrophysics Data System (ADS)

    Kiers, R. F. C.

    1984-08-01

    Origins of cabin noise in propeller driven aircraft (PDE) and the importance of further reductions are described. Trends in propeller technology and fuselage construction are aimed at the development of extremely fuel-efficient PDE. However, the related increase of cabin noise levels urges the extension of noise reduction in PDE. Fokker noise reduction methodology for meeting the challenge of maintaining and improving noise levels in future PDE is discussed. Additional noise reduction is hard to obtain. Sophisticated techniques were used to acquire the necessary data and take effective noise reduction measures.

  5. STOL Aircraft

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Michael E. Fisher, President of AeroVisions International, has introduced the Culex light twin engine aircraft which offers economy of operation of a single engine plane, the ability to fly well on one engine, plus the capability of flying from short, unimproved fields of takeoff and landing distances less than 35 feet. Key element of design is an airfoil developed by Langley. Culex was originally intended to be factory built aircraft for special utility markets. However, it is now offered as a build-it-yourself kit plane.

  6. Testing composite-to-metal tubular lap joints

    NASA Astrophysics Data System (ADS)

    Guess, T. R.; Reedy, E. D., Jr.; Slavin, A. M.

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  7. Large-Scale Advanced Prop-Fan (LAP) blade design

    NASA Technical Reports Server (NTRS)

    Violette, John A.; Sullivan, William E.; Turnberg, Jay E.

    1984-01-01

    This report covers the design analysis of a very thin, highly swept, propeller blade to be used in the Large-Scale Advanced Prop-Fan (LAP) test program. The report includes: design requirements and goals, a description of the blade configuration which meets requirements, a description of the analytical methods utilized/developed to demonstrate compliance with the requirements, and the results of these analyses. The methods described include: finite element modeling, predicted aerodynamic loads and their application to the blade, steady state and vibratory response analyses, blade resonant frequencies and mode shapes, bird impact analysis, and predictions of stalled and unstalled flutter phenomena. Summarized results include deflections, retention loads, stress/strength comparisons, foreign object damage resistance, resonant frequencies and critical speed margins, resonant vibratory mode shapes, calculated boundaries of stalled and unstalled flutter, and aerodynamic and acoustic performance calculations.

  8. Testing composite-to-metal tubular lap joints

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.; Slavin, A.M.

    1993-11-01

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  9. Deformations and strains in a thick adherend lap joint

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Wood, J. D.; Joh, D.

    1988-01-01

    Displacement fields in a thick adherend lap joint were measured by high-sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherend surfaces. Loads ranged from a modest load to a near-failure load. Quantitative results are given for displacements and strains in the adhesive and along the adhesive/adherend boundary lines. The results show nearly constant shear strain in the adhesive, nonlinear strains as a function of load or average shear stress, and viscoelastic or time-dependent response. Longitudinal normal strains in the adhesive are nearly two orders of magnitude less than the shear strains. With its subwavelength displacement resolution and high spatial resolution, moire interferometry is especially well suited for deformation studies of adhesive joints.

  10. XSECT: A computer code for generating fuselage cross sections - user's manual

    NASA Technical Reports Server (NTRS)

    Ames, K. R.

    1982-01-01

    A computer code, XSECT, has been developed to generate fuselage cross sections from a given area distribution and wing definition. The cross sections are generated to match the wing definition while conforming to the area requirement. An iterative procedure is used to generate each cross section. Fuselage area balancing may be included in this procedure if desired. The code is intended as an aid for engineers who must first design a wing under certain aerodynamic constraints and then design a fuselage for the wing such that the contraints remain satisfied. This report contains the information necessary for accessing and executing the code, which is written in FORTRAN to execute on the Cyber 170 series computers (NOS operating system) and produces graphical output for a Tektronix 4014 CRT. The LRC graphics software is used in combination with the interface between this software and the PLOT 10 software.

  11. Flow fields and aerodynamic characteristics for hypersonic missiles with mid-fuselage inlets

    NASA Technical Reports Server (NTRS)

    Hunt, J. L.; Johnston, P. J.; Riebe, G. D.

    1983-01-01

    A study was made to quantify forebody flow fields and to evaluate aerodynamic performance trends on a matrix of fuselage shapes for the mid-inlet/bolt-on-engine class of hypersonic airbreathing missiles for the Navy's vertical box launcher. The study indicated that inlet mass flow and pressure recovery can be increased by cambering the nose and increasing the width of the fuselage at both Mach 4 acceleration and Mach 6 cruise conditions. Aerodynamic trim predictions show that the drag at zero lift at Mach 4 decreases while the L/D max at Mach 6 increases with the nose camber, although these tendencies reverse with increasing width of maximum fuselage cross section.

  12. Leeward centerline and side fuselage entry heating predictions for the space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Helms, V. T., III

    1983-01-01

    Heat transfer data measured along the leeward centerline and on the side fuselage of the Space Shuttle orbiter during STS-2 and STS-3 are compared with predictions of empirical heating techniques derived from wind tunnel tests. Steps required to extrapolate an existing leeward centerline theory to flight conditions are described. Generally favorable comparisons from Mach 24 down to approximately Mach 7 for both flights are presented. The side fuselage impingement heating method is currently under development, but some preliminary results are available. The method is briefly described and compared with wind tunnel and flight measurements. Side heating predictions are given for an STS-3 trajectory point near Mach 10 showing good agreement with flight data. There is evidence of embedded vortices emanating from the side fuselage impingement line which significantly enhance local heating rates at both wind tunnel and flight conditions.

  13. Multi-Terrain Impact Testing and Simulation of a Composite Energy Absorbing Fuselage Section

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Jackson, Karen E.; Lyle, Karen H.; Sparks, Chad E.; Sareen, Ashish K.

    2007-01-01

    Comparisons of the impact performance of a 5-ft diameter crashworthy composite fuselage section were investigated for hard surface, soft soil, and water impacts. The fuselage concept, which was originally designed for impacts onto a hard surface only, consisted of a stiff upper cabin, load bearing floor, and an energy absorbing subfloor. Vertical drop tests were performed at 25-ft/s onto concrete, soft-soil, and water at NASA Langley Research Center. Comparisons of the peak acceleration values, pulse durations, and onset rates were evaluated for each test at specific locations on the fuselage. In addition to comparisons of the experimental results, dynamic finite element models were developed to simulate each impact condition. Once validated, these models can be used to evaluate the dynamic behavior of subfloor components for improved crash protection for hard surface, soft soil, and water impacts.

  14. Multi-Terrain Impact Testing and Simulation of a Composite Energy Absorbing Fuselage Section

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Lyle, Karen H.; Sparks, Chad E.; Sareen, Ashish K.

    2004-01-01

    Comparisons of the impact performance of a 5-ft diameter crashworthy composite fuselage section were investigated for hard surface, soft soil, and water impacts. The fuselage concept, which was originally designed for impacts onto a hard surface only, consisted of a stiff upper cabin, load bearing floor, and an energy absorbing subfloor. Vertical drop tests were performed at 25-ft/s onto concrete, soft-soil, and water at NASA Langley Research Center. Comparisons of the peak acceleration values, pulse durations, and onset rates were evaluated for each test at specific locations on the fuselage. In addition to comparisons of the experimental results, dynamic finite element models were developed to simulate each impact condition. Once validated, these models can be used to evaluate the dynamic behavior of subfloor components for improved crash protection for hard surface, soft soil, and water impacts.

  15. Lamina Associated Polypeptide 1 (LAP1) Interactome and Its Functional Features

    PubMed Central

    Serrano, Joana B.; da Cruz e Silva, Odete A. B.; Rebelo, Sandra

    2016-01-01

    Lamina-associated polypeptide 1 (LAP1) is a type II transmembrane protein of the inner nuclear membrane encoded by the human gene TOR1AIP1. LAP1 is involved in maintaining the nuclear envelope structure and appears be involved in the positioning of lamins and chromatin. To date, LAP1’s precise function has not been fully elucidated but analysis of its interacting proteins will permit unraveling putative associations to specific cellular pathways and cellular processes. By assessing public databases it was possible to identify the LAP1 interactome, and this was curated. In total, 41 interactions were identified. Several functionally relevant proteins, such as TRF2, TERF2IP, RIF1, ATM, MAD2L1 and MAD2L1BP were identified and these support the putative functions proposed for LAP1. Furthermore, by making use of the Ingenuity Pathways Analysis tool and submitting the LAP1 interactors, the top two canonical pathways were “Telomerase signalling” and “Telomere Extension by Telomerase” and the top functions “Cell Morphology”, “Cellular Assembly and Organization” and “DNA Replication, Recombination, and Repair”. Once again, putative LAP1 functions are reinforced but novel functions are emerging. PMID:26784240

  16. 78 FR 68775 - Special Conditions: Airbus, Model A350-900 Series Airplane; Composite Fuselage In-Flight Fire...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-15

    ... the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as at http://DocketsInfo...; Composite Fuselage In-Flight Fire/Flammability Resistance AGENCY: Federal Aviation Administration (FAA), DOT... associated with the in-flight fire and flammability resistance of the composite fuselage. Experience...

  17. Blended-Wing-Body (BWB) Fuselage Structural Design for Weight Reduction

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, V.

    2005-01-01

    Structural analysis and design of efficient pressurized fuselage configurations for the advanced Blended-Wing-Body (BWB) flight vehicle is a challenging problem. Unlike a conventional cylindrical pressurized fuselage, stress level in a box type BWB fuselage is an order of magnitude higher, because internal pressure primarily results in bending stress instead of skin-membrane stress. In addition, resulting deformation of aerodynamic surface could significantly affect performance advantages provided by lifting body. The pressurized composite conformal multi-lobe tanks of X-33 type space vehicle also suffered from similar problem. In the earlier BWB design studies, Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS); Vaulted shell Honeycomb Core (VLHC) and Flat sandwich shell Honeycomb Core (FLHC) concepts were studied. The flat and vaulted ribbed shell concepts were found most efficient. In a recent study, a set of composite sandwich panel and cross-ribbed panel were analyzed. Optimal values of rib and skin thickness, rib spacing, and panel depth were obtained for minimal weight under stress and buckling constraints. In addition, a set of efficient multi-bubble fuselage (MBF) configuration concept was developed. The special geometric configuration of this concept allows for balancing internal cabin pressure load efficiently, through membrane stress in inner-stiffened shell and inter-cabin walls, while the outer-ribbed shell prevents buckling due to external resultant compressive loads. The initial results from these approximate finite element analyses indicate progressively lower maximum stresses and deflections compared to the earlier study. However, a relative comparison of the FEM weight per unit floor area of the segment unit indicates that the unit weights are still relatively higher that the conventional B777 type cylindrical or A380 type elliptic fuselage design. Due to the manufacturing concern associated with multi-bubble fuselage, a Y braced box

  18. Calculation of the forces and moments on a slender fuselage and vertical fin penetrating lateral gusts

    NASA Technical Reports Server (NTRS)

    Eggleston, John M

    1956-01-01

    A theory is presented for calculating the variation with frequency of the lateral-force and yawing-moment coefficients due to sinusoidal side gusts passing over the profile of a simple fuselage-vertical-fin combination. The analysis is based on slender-body theory. The method considers the penetration effect of both fuselage and vertical tail in calculating side force and yawing moment due to side gusts, as opposed to a simple lag concept which considers the flow angle to be uniform over the configuration.

  19. Use of two-dimensional transmission photoelastic models to study stresses in double-lap bolted joints

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Liu, D. H.

    1981-01-01

    The stress distribution in two hole connectors in a double lap joint configuration was studied. The following steps are described: (1) fabrication of photoelastic models of double lap double hole joints designed to determine the stresses in the inner lap; (2) assessment of the effects of joint geometry on the stresses in the inner lap; and (3) quantification of differences in the stresses near the two holes. The two holes were on the centerline of the joint and the joints were loaded in tension, parallel to the centerline. Acrylic slip fit pins through the holes served as fasteners. Two dimensional transmission photoelastic models were fabricated by using transparent acrylic outer laps and a photoelastic model material for the inner laps. It is concluded that the photoelastic fringe patterns which are visible when the models are loaded are due almost entirely to stresses in the inner lap.

  20. Global-Local Finite Element Analysis of Bonded Single-Lap Joints

    NASA Technical Reports Server (NTRS)

    Kilic, Bahattin; Madenci, Erdogan; Ambur, Damodar R.

    2004-01-01

    Adhesively bonded lap joints involve dissimilar material junctions and sharp changes in geometry, possibly leading to premature failure. Although the finite element method is well suited to model the bonded lap joints, traditional finite elements are incapable of correctly resolving the stress state at junctions of dissimilar materials because of the unbounded nature of the stresses. In order to facilitate the use of bonded lap joints in future structures, this study presents a finite element technique utilizing a global (special) element coupled with traditional elements. The global element includes the singular behavior at the junction of dissimilar materials with or without traction-free surfaces.

  1. The effect of diamond powder characteristics on lapping of sintered silicon carbide

    NASA Astrophysics Data System (ADS)

    Rosczyk, Benjamin; Burkam, Eric; Titov, Artem; Onyenemezu, Clement; Benea, Ion C.

    2015-10-01

    In Automotive applications, sintered Silicon Carbide has been used in applications such as seal pump faces. The surface of sintered SiC, when lapped or polished for sealing to another surface, must be free of blemishes and mechanical defects. Lapping and polishing processes therefore must be well defined and controlled assuring minimal variation and production scrap. In this study, we related the characteristics of different diamond powders (particle size distribution, particle shape and surface) to their performance in lapping of sintered silicon carbide material, expressed as removal rate and surface finish.

  2. Electromechanical behaviour of REBCO tape lap splices under transverse compressive loading

    NASA Astrophysics Data System (ADS)

    Grether, A.; Scheuerlein, C.; Ballarino, A.; Bottura, L.

    2016-07-01

    We have studied the influence of transverse compressive stress on the resistance and critical current (I c ) of soldered REBCO tape lap splices. Internal contact resistances dominate the overall REBCO lap splice resistances. Application of transverse compressive stress up to 250 MPa during the resistance measurements does not alter the resistance and I c of the soldered REBCO splices that were studied. The resistance of unsoldered REBCO tape lap splices depends strongly on the contact pressure. At a transverse compressive stress of 100 MPa, to which Roebel cables are typically exposed in high field magnets, the crossover splice contact resistance is comparable to the internal tape resistances.

  3. Machine imparting complex rotary motion for lapping a spherical inner diameter

    DOEpatents

    Carroll, T.A.; Yetter, H.H.

    1985-01-30

    An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

  4. Machine imparting complex rotary motion for lapping a spherical inner diameter

    DOEpatents

    Carroll, Thomas A.; Yetter, Harold H.

    1986-01-01

    An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

  5. Aircraft cybernetics

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The use of computers for aircraft control, flight simulation, and inertial navigation is explored. The man-machine relation problem in aviation is addressed. Simple and self-adapting autopilots are described and the assets and liabilities of digital navigation techniques are assessed.

  6. A study of the TCAS 2 collision avoidance system mounted on a Boeing 737 aircraft

    NASA Technical Reports Server (NTRS)

    Grandchamp, B.; Burnside, W. D.; Rojas, R. G.

    1987-01-01

    The purpose of this report is to determine the effects of scattering from major aircraft structures on the TCAS 2 collision avoidance system mounted on a Boeing 737. It is found that the major source of scattering for angles of observation above the horizon is the vertical stabilizer and that its effect may be greatly reduced by mounting the TCAS 2 array close to the nose of the aircraft. In addition, by mounting the array close to the nose, the effects of fuselage blockage on the array patterns at elevation angles below the horizon may be greatly reduced in the forward direction.

  7. Drag Reduction Devices for Aircraft (Latest Citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning the modeling, application, testing, and development of drag reduction devices for aircraft. Slots, flaps, fences, large-eddy breakup (LEBU) devices, vortex generators and turbines, Helmholtz resonators, and winglets are among the devices discussed. Contour shaping to ensure laminar flow, control boundary layer transition, or minimize turbulence is also covered. Applications include the wings, nacelles, fuselage, empennage, and externals of aircraft designed for high-lift, subsonic, or supersonic operation. The design, testing, and development of directional grooves, commonly called riblets, are covered in a separate bibliography.(Contains 50-250 citations and includes a subject term index and title list.)

  8. Roles of Cyclic Di-GMP and the Gac System in Transcriptional Control of the Genes Coding for the Pseudomonas putida Adhesins LapA and LapF

    PubMed Central

    Martínez-Gil, Marta; Ramos-González, María Isabel

    2014-01-01

    LapA and LapF are large extracellular proteins that play a relevant role in biofilm formation by Pseudomonas putida. Current evidence favors a sequential model in which LapA is first required for the initial adhesion of individual bacteria to a surface, while LapF participates in later stages of biofilm development. In agreement with this model, lapF transcription was previously shown to take place at late times of growth and to respond to the stationary-phase sigma factor RpoS. We have now analyzed the transcription pattern of lapA and other regulatory elements that influence expression of both genes. The lapA promoter shows a transient peak of activation early during growth, with a second increase in stationary phase that is independent of RpoS. The same pattern is observed in biofilms although expression is not uniform in the population. Both lapA and lapF are under the control of the two-component regulatory system GacS/GacA, and their transcription also responds to the intracellular levels of the second messenger cyclic diguanylate (c-di-GMP), although in surprisingly reverse ways. Whereas expression from the lapA promoter increases with high levels of c-di-GMP, the opposite is true for lapF. The transcriptional regulator FleQ is required for the modulation of lapA expression by c-di-GMP but has a minor influence on lapF. This work represents a further step in our understanding of the regulatory interactions controlling biofilm formation in P. putida. PMID:24488315

  9. Alteration of Sulphides in the Rumuruti Chondrite La Paz Icefield (LAP) 031275

    NASA Astrophysics Data System (ADS)

    Steer, E. D.; Treiman, A. H.

    2014-09-01

    Pyrrhotite in LAP 03175 (R5) has altered to a fine-grained mineral mixture. New data (optical, chemical, and Raman) suggest the mixture includes violarite and tochilinite, but not (as suggested earlier) graphite, hematite, and/or jarosite.

  10. A Short Method of Calculating Torsional Stresses in an Airplane Fuselage

    NASA Technical Reports Server (NTRS)

    Younger, John E

    1924-01-01

    This report deals with an investigation carried out in the Civil Engineering Laboratory of the University of California, to determine the accuracy of existing methods of computing the stresses in an airplane fuselage when subjected to torsion, and to derive a simple approximate formula for the rapid calculation of these stresses.

  11. Study of multiple cracks in airplane fuselage by micromechanics and complex variables

    NASA Technical Reports Server (NTRS)

    Denda, Mitsunori; Dong, Y. F.

    1994-01-01

    Innovative numerical techniques for two dimensional elastic and elastic-plastic multiple crack problems are presented using micromechanics concepts and complex variables. The simplicity and the accuracy of the proposed method will enable us to carry out the multiple-site fatigue crack propagation analyses for airplane fuselage by incorporating such features as the curvilinear crack path, plastic deformation, coalescence of cracks, etc.

  12. Mechanisms of Active Aerodynamic Load Reduction on a Rotorcraft Fuselage With Rotor Effects

    NASA Technical Reports Server (NTRS)

    Schaeffler, Norman W.; Allan, Brian G.; Jenkins, Luther N.; Yao, Chung-Sheng; Bartram, Scott M.; Mace, W. Derry; Wong, Oliver D.; Tanner, Philip E.

    2016-01-01

    The reduction of the aerodynamic load that acts on a generic rotorcraft fuselage by the application of active flow control was investigated in a wind tunnel test conducted on an approximately 1/3-scale powered rotorcraft model simulating forward flight. The aerodynamic mechanisms that make these reductions, in both the drag and the download, possible were examined in detail through the use of the measured surface pressure distribution on the fuselage, velocity field measurements made in the wake directly behind the ramp of the fuselage and computational simulations. The fuselage tested was the ROBIN-mod7, which was equipped with a series of eight slots located on the ramp section through which flow control excitation was introduced. These slots were arranged in a U-shaped pattern located slightly downstream of the baseline separation line and parallel to it. The flow control excitation took the form of either synthetic jets, also known as zero-net-mass-flux blowing, and steady blowing. The same set of slots were used for both types of excitation. The differences between the two excitation types and between flow control excitation from different combinations of slots were examined. The flow control is shown to alter the size of the wake and its trajectory relative to the ramp and the tailboom and it is these changes to the wake that result in a reduction in the aerodynamic load.

  13. Hybrid-Wing-Body Vehicle Composite Fuselage Analysis and Case Study

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    2014-01-01

    Recent progress in the structural analysis of a Hybrid Wing-Body (HWB) fuselage concept is presented with the objective of structural weight reduction under a set of critical design loads. This pressurized efficient HWB fuselage design is presently being investigated by the NASA Environmentally Responsible Aviation (ERA) project in collaboration with the Boeing Company, Huntington Beach. The Pultruded Rod-Stiffened Efficient Unitized Structure (PRSEUS) composite concept, developed at the Boeing Company, is approximately modeled for an analytical study and finite element analysis. Stiffened plate linear theories are employed for a parametric case study. Maximum deflection and stress levels are obtained with appropriate assumptions for a set of feasible stiffened panel configurations. An analytical parametric case study is presented to examine the effects of discrete stiffener spacing and skin thickness on structural weight, deflection and stress. A finite-element model (FEM) of an integrated fuselage section with bulkhead is developed for an independent assessment. Stress analysis and scenario based case studies are conducted for design improvement. The FEM model specific weight of the improved fuselage concept is computed and compared to previous studies, in order to assess the relative weight/strength advantages of this advanced composite airframe technology

  14. Composition of matrix in the CR chondrite LAP 02342

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Rubin, Alan E.

    2009-03-01

    We report evidence of interchondrule matrix heterogeneity on a scale of ˜50 μm in the well-preserved CR2 chondrite LAP 02342. Despite minor effects resulting from asteroidal aqueous alteration, the matrix in this CR chondrite seems to preserve much of the compositional record of nebular fines. We carried out electron-microprobe studies using a 3-μm-diameter beam; we analyzed 10 elements in 36- or 49-point grids on 11 ca. 50 × 50-μm rectangular areas of matrix. Each grid area has a distinct composition, inconsistent with a simple model of matrix material having a uniform composition throughout the nebular formation region of the CR chondrites. On S-Fe, Mg-Si, K-Na and K-Al scatter diagrams, the grid areas (i.e., different matrix patches) are largely separated from each other; plots of means with 95% confidence limits demonstrate that the compositions are resolvable. Five matrix areas were analyzed again in duplicate runs; excellent agreement was observed between duplicate studies. LAP 02342 experienced two forms of mild aqueous alteration - as patchy enrichments in Ca (inferred to reflect CaCO 3) and as regions in which sulfide laths are embedded within phyllosilicates. Despite this evidence of aqueous transport, the effect on the composition of matrix is not resolvable. For example, matrix points that were adjacent to points with high CaCO 3 contents show elemental concentrations similar to those in regions having only one or two points with a Ca enrichment. It appears that secondary minerals are found in areas where there are suitable precursor phases and voids into which new phases could grow unimpeded. Calcium appears to be unique in forming a phase that greatly lowers the Ca ++ content of the aqueous medium, thus enhancing the rate of diffusion. Because chondrules vary widely in bulk composition, the formation of chondrules in small sets (100 or less) could generate "smoke" and mesostasis spray with compositions unique to each set. However, if these

  15. Crystal structure, spectroscopic and thermal properties of [Zn(Lap)2(DMF)(H2O)] and isomorphous [M(Lap)2]n (M: Cd, Mn) complexes

    NASA Astrophysics Data System (ADS)

    Farfán, R. A.; Espíndola, J. A.; Gomez, M. I.; de Jiménez, M. C. L.; Piro, O. E.; Castellano, E. E.; Martínez, M. A.

    2015-05-01

    The solid state structure of the lapacholate (Lap-) complexes with Zn(II), Cd(II) and Mn(II) were determined by X-ray diffraction methods. [Zn(Lap)2(DMF)(H2O)] crystallizes in the triclinic space group P 1 bar with a = 10.5051(4), b = 12.8020(4), c = 13.0394(4) Å, α = 60.418(2), β = 83.904(2), γ = 86.206(2)°, and Z = 2 molecules per unit cell. The isomorphous complexes [M(Lap)2]n (M: Cd, Mn) crystallize in the tetragonal space group P43212 with a = b = 13.5770(6) Å, c = 14.5730(6) Å (Cd), and a = b = 13.3539(4), c = 14.7148(4) Å (Mn), and Z = 4. In [Zn(Lap)2(DMF)(H2O)] the Zn(II) ion is in a distorted octahedral environment coordinated to two different and nearly perpendicular Lap- molecules acting as bidentate ligands through their adjacent carbonyl and phenol oxygen atoms. The remaining two cis-coordination sites are occupied by water and DMF molecules. [M(Lap)2]n (M: Cd, Mn) isomorphous complexes are also octahedral and present a supra-molecular arrangement in the lattice. There is only one independent Lap- molecule that coordinates the metal through all three ligand binding sites, giving rise to a 3-D structure of [M(Lap)2]n complexes that extends throughout the crystal lattice. The lapachol binding to metal is also revealed by the IR spectra. In fact, the carbonyl Cdbnd O stretching frequency is appreciable red-shifted in the complexes as compared to uncoordinated lapachol ligand. As expected, the IR and UV-Vis spectra of the isomorphous pair of complexes closely resemble to each other. Up to above 300 °C there are significant differences in the TGA of the Zn complex when compared with the isomorphous pair: while the former shows the loss of the secondary ligands (water and DMF), the latter exhibits a plateau signaling the lesser labile character of the lapacholate ligand.

  16. Virtual Sensor for Failure Detection, Identification and Recovery in the Transition Phase of a Morphing Aircraft

    PubMed Central

    Heredia, Guillermo; Ollero, Aníbal

    2010-01-01

    The Helicopter Adaptive Aircraft (HADA) is a morphing aircraft which is able to take-off as a helicopter and, when in forward flight, unfold the wings that are hidden under the fuselage, and transfer the power from the main rotor to a propeller, thus morphing from a helicopter to an airplane. In this process, the reliable folding and unfolding of the wings is critical, since a failure may determine the ability to perform a mission, and may even be catastrophic. This paper proposes a virtual sensor based Fault Detection, Identification and Recovery (FDIR) system to increase the reliability of the HADA aircraft. The virtual sensor is able to capture the nonlinear interaction between the folding/unfolding wings aerodynamics and the HADA airframe using the navigation sensor measurements. The proposed FDIR system has been validated using a simulation model of the HADA aircraft, which includes real phenomena as sensor noise and sampling characteristics and turbulence and wind perturbations. PMID:22294922

  17. Virtual sensor for failure detection, identification and recovery in the transition phase of a morphing aircraft.

    PubMed

    Heredia, Guillermo; Ollero, Aníbal

    2010-01-01

    The Helicopter Adaptive Aircraft (HADA) is a morphing aircraft which is able to take-off as a helicopter and, when in forward flight, unfold the wings that are hidden under the fuselage, and transfer the power from the main rotor to a propeller, thus morphing from a helicopter to an airplane. In this process, the reliable folding and unfolding of the wings is critical, since a failure may determine the ability to perform a mission, and may even be catastrophic. This paper proposes a virtual sensor based Fault Detection, Identification and Recovery (FDIR) system to increase the reliability of the HADA aircraft. The virtual sensor is able to capture the nonlinear interaction between the folding/unfolding wings aerodynamics and the HADA airframe using the navigation sensor measurements. The proposed FDIR system has been validated using a simulation model of the HADA aircraft, which includes real phenomena as sensor noise and sampling characteristics and turbulence and wind perturbations. PMID:22294922

  18. Actively Controlled Landing Gear for Aircraft Vibration Reduction

    NASA Technical Reports Server (NTRS)

    Horta, Lucas G.; Daugherty, Robert H.; Martinson, Veloria J.

    1999-01-01

    Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads using actively controlled landing gears. A facility has been developed to test various active landing gear control concepts and their performance. The facility uses a NAVY A6-intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented including modifications to actuate the gear externally and test data is used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

  19. Emergency in-flight egress opening for general aviation aircraft

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1980-01-01

    In support of a stall/spin research program, an emergency in-flight egress system is being installed in a light general aviation airplane. To avoid a major structural redesign for a mechanical door, an add-on 11.2 kg pyrotechnic-actuated system was developed to create an opening in the existing structure. The airplane skin will be explosively severed around the side window, across a central stringer, and down to the floor, creating an opening of approximately 76 by 76 cm. The severed panel will be jettisoned at an initial velocity of approximately 13.7 m/sec. System development included a total of 68 explosive severance tests on aluminum material using small samples, small and full scale flat panel aircraft structural mock-ups, and an actual aircraft fuselage. These tests proved explosive sizing/severance margins, explosive initiation, explosive product containment, and system dynamics.

  20. Structural health monitoring and impact detection for primary aircraft structures

    NASA Astrophysics Data System (ADS)

    Kosters, Eric; van Els, Thomas J.

    2010-04-01

    The increasing use of thermoplastic carbon fiber-reinforced plastic (CFRP) materials in the aerospace industry for primary aircraft structures, such as wing leading-edge surfaces and fuselage sections, has led to rapid growth in the field of structural health monitoring (SHM). Impact, vibration, and load can all cause failure, such as delamination and matrix cracking, in composite materials. Moreover, the internal material damage can occur without being visible to the human eye, making inspection of and clear insight into structural integrity difficult using currently available evaluation methods. Here, we describe the detection of impact and its localization in materials and structures by high-speed interrogation of multiple-fiber Bragg grating (FBG) sensors mounted on a composite aircraft component.

  1. Aircraft Engine Noise Scattering - A Discontinuous Spectral Element Approach

    NASA Technical Reports Server (NTRS)

    Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2002-01-01

    The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far-field. The effects of nonuniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. Our approach is based on the discretization of the inviscid flow equations through a collocation form of the Discontinuous Galerkin spectral element method. An isoparametric representation of the underlying geometry is used in order to take full advantage of the spectral accuracy of the method. Largescale computations are made possible by a parallel implementation based on message passing. Results obtained for radiation from an axisymmetric nacelle alone are compared with those obtained when the same nacelle is installed in a generic con.guration, with and without a wing.

  2. Water Impact Test and Simulation of a Composite Energy Absorbing Fuselage Section

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Jackson, Karen E.; Sparks, Chad; Sareen, Ashish

    2003-01-01

    In March 2002, a 25-ft/s vertical drop test of a composite fuselage section was conducted onto water. The purpose of the test was to obtain experimental data characterizing the structural response of the fuselage section during water impact for comparison with two previous drop tests that were performed onto a rigid surface and soft soil. For the drop test, the fuselage section was configured with ten 100-lb. lead masses, five per side, that were attached to seat rails mounted to the floor. The fuselage section was raised to a height of 10-ft. and dropped vertically into a 15-ft. diameter pool filled to a depth of 3.5-ft. with water. Approximately 70 channels of data were collected during the drop test at a 10-kHz sampling rate. The test data were used to validate crash simulations of the water impact that were developed using the nonlinear, explicit transient dynamic codes, MSC.Dytran and LS-DYNA. The fuselage structure was modeled using shell and solid elements with a Lagrangian mesh, and the water was modeled with both Eulerian and Lagrangian techniques. The fluid-structure interactions were executed using the fast general coupling in MSC.Dytran and the Arbitrary Lagrange-Euler (ALE) coupling in LS-DYNA. Additionally, the smooth particle hydrodynamics (SPH) meshless Lagrangian technique was used in LS-DYNA to represent the fluid. The simulation results were correlated with the test data to validate the modeling approach. Additional simulation studies were performed to determine how changes in mesh density, mesh uniformity, fluid viscosity, and failure strain influence the test-analysis correlation.

  3. Fatigue strength of a single lap joint SPR-bonded

    SciTech Connect

    Di Franco, G.; Fratini, L.; Pasta, A.

    2011-05-04

    In the last years, hybrid joints, meaning with this the joints which consist in combining a traditional mechanical joint to a layer of adhesive, are gradually attracting the attention of various sectors of the construction of vehicles and transportation industries, for their better performance compared to just mechanical joints (self-piercing riveting SPR, riveting, and so on) or just to bonded joints.The paper investigates the fatigue behavior of a single lap joint self-piercing riveted (SPR) and bonded throughout fatigue tests. The considered geometric configuration allowed the use of two rivets placed longitudinally; an epoxy resin was used as adhesive. In the first part of the work static characterization of the joints was carried out through tensile tests. Then fatigue tests were made with the application of different levels of load. The fatigue curves were also obtained at the varying the distance between the two rivets in order to better assess the joint strength for a given length of overlap.

  4. Experimental Investigations of an Inclined Lap-Type Bolted Joint

    SciTech Connect

    GREGORY, DANNY LYNN; RESOR, BRIAN R.; COLEMAN, RONALD G.; SMALLWOOD, DAVID ORA

    2003-04-01

    The dynamic response of critical aerospace components is often strongly dependent upon the dynamic behavior of bolted connections that attach the component to the surrounding structure. These bolted connections often provide the only structural load paths to the component. The bolted joint investigated in this report is an inclined lap-type joint with the interface inclined with respect to the line of action of the force acting on the joint. The accurate analytical modeling of these bolted connections is critical to the prediction of the response of the component to normal and high-level shock environmental loadings. In particular, it is necessary to understand and correctly model the energy dissipation (damping) of the bolted joint that is a nonlinear function of the forces acting on the joint. Experiments were designed and performed to isolate the dynamics of a single bolted connection of the component. Steady state sinusoidal and transient experiments were used to derive energy dissipation curves as a function of input force. Multiple assemblies of the bolted connection were also observed to evaluate the variability of the energy dissipation of the connection. These experiments provide insight into the complex behavior of this bolted joint to assist in the postulation and development of reduced order joint models to capture the important physics of the joint including stiffness and damping. The experiments are described and results presented that provide a basis for candidate joint model calibration and comparison.

  5. Rotor systems research aircraft predesign study. Volume 2: Conceptual study report

    NASA Technical Reports Server (NTRS)

    Schmidt, S. A.; Linden, A. W.

    1972-01-01

    The overall feasibility of the technical requirements and concepts for a rotor system research aircraft (RSRA) was determined. The designs of two aircraft were then compared against the RSRA requirements. One of these is an all new aircraft specifically designed as an RSRA vehicle. A new main rotor, transmission, wings, and fuselage are included in this design. The second aircraft uses an existing Sikorsky S-61 main rotor, an S-61 roller gearbox, and a highly modified Sikorsky S-67 airframe. The wing for this aircraft is a new design. Both aircraft employ a fan-in-fin anti-torque/yaw control system, T58-GE-16 engines for rotor power, and TF34-GE-2 turbofans for auxiliary thrust. Each aircraft meets the basic requirements and goals of the program. The all new aircraft has inflight variable main rotor shaft tilt, a side-by-side cockpit seating arrangement, and is slightly faster in the compound mode. It is also somewhat lighter since it uses new dynamic components specifically designed for the RSRA. Preliminary development plans, including schedules and costs, were prepared for both of these aircraft.

  6. A Study of Vehicle Structural Layouts in Post-WWII Aircraft

    NASA Technical Reports Server (NTRS)

    Sensmeier, Mark D.; Samareh, Jamshid A.

    2004-01-01

    In this paper, results of a study of structural layouts of post-WWII aircraft are presented. This study was undertaken to provide the background information necessary to determine typical layouts, design practices, and industry trends in aircraft structural design. Design decisions are often predicated not on performance-related criteria, but rather on such factors as manufacturability, maintenance access, and of course cost. For this reason, a thorough understanding of current best practices in the industry is required as an input for the design optimization process. To determine these best practices and industry trends, a large number of aircraft structural cutaway illustrations were analyzed for five different aircraft categories (commercial transport jets, business jets, combat jet aircraft, single engine propeller aircraft, and twin-engine propeller aircraft). Several aspects of wing design and fuselage design characteristics are presented here for the commercial transport and combat aircraft categories. A great deal of commonality was observed for transport structure designs over a range of eras and manufacturers. A much higher degree of variability in structural designs was observed for the combat aircraft, though some discernable trends were observed as well.

  7. LAPS Lidar Measurements at the ARM Alaska Northslope Site (Support to FIRE Project)

    NASA Technical Reports Server (NTRS)

    Philbrick, C. Russell; Lysak, Daniel B., Jr.; Petach, Tomas M.; Esposito, Steven T.; Mulik, Karoline R.

    1998-01-01

    This report consists of data summaries of the results obtained during the May 1998 measurement period at Barrow Alaska. This report does not contain any data interpretation or analysis of the results which will follow this activity. This report is forwarded with a data set on magnetic media which contains the reduced data from the LAPS lidar in 15 minute intervals. The data was obtained during the period 15-30 May 1998. The measurement period overlapped with several aircraft flights conducted by NASA as part of the FIRE project. The report contains a summary list of the data obtained plus figures that have been prepared to help visualize the measurement periods. The order of the presentation is as follows: Section 1. A copy of the Statement of Work for the planned activity of the second measurement period at the ARM Northslope site is provided. Section 2. A list of the data collection periods shows the number of one minute data records stored during each hour of operation and the corresponding size (Mbytes) of the one hour data folders. The folder and file names are composed from the year, month, day, hour and minute. The date/time information is given in UTC for easier comparison with other data sets. Section 3. A set of 4 comparisons between the LAPS lidar results and the sondes released by the ARM scientists from a location nearby the lidar. The lidar results show the +/- 1 sigma statistical error on each of the independent 75 m altitude bins of the data. This set of 4 comparisons was used to set and validate the calibration value which was then used for the complete data set. Section 4. A set of false color figures with up to 10 hours of specific humidity measurements are shown in each graph. Two days of measurements are shown on each page. These plots are crude representations of the data and permit a survey which indicates when the clouds were very low or where interesting events may occur in the results. These plots are prepared using the real time sequence

  8. Aerodynamic interference effects on tilting proprotor aircraft. [using the Green function method

    NASA Technical Reports Server (NTRS)

    Soohoo, P.; Morino, L.; Noll, R. B.; Ham, N. D.

    1977-01-01

    The Green's function method was used to study tilting proprotor aircraft aerodynamics with particular application to the problem of the mutual interference of the wing-fuselage-tail-rotor wake configuration. While the formulation is valid for fully unsteady rotor aerodynamics, attention was directed to steady state aerodynamics, which was achieved by replacing the rotor with the actuator disk approximation. The use of an actuator disk analysis introduced a mathematical singularity into the formulation; this problem was studied and resolved. The pressure distribution, lift, and pitching moment were obtained for an XV-15 wing-fuselage-tail rotor configuration at various flight conditions. For the flight configurations explored, the effects of the rotor wake interference on the XV-15 tilt rotor aircraft yielded a reduction in the total lift and an increase in the nose-down pitching moment. This method provides an analytical capability that is simple to apply and can be used to investigate fuselage-tail rotor wake interference as well as to explore other rotor design problem areas.

  9. B-52 Launch Aircraft in Flight

    NASA Technical Reports Server (NTRS)

    2001-01-01

    the development of parachute recovery systems used to recover the space shuttle solid rocket booster casings. It also supported eight orbiter (space shuttle) drag chute tests in 1990. In addition, the B-52 served as the air launch platform for the first six Pegasus space boosters. During its many years of service, the B-52 has undergone several modifications. The first major modification was made by North American Aviation (now part of Boeing) in support of the X-15 program. This involved creating a launch-panel-operator station for monitoring the status of the test vehicle being carried, cutting a large notch in the right inboard wing flap to accommodate the vertical tail of the X-15 aircraft, and installing a wing pylon that enables the B-52 to carry research vehicles and test articles to be air-launched/dropped. Located on the right wing, between the inboard engine pylon and the fuselage, this wing pylon was subjected to extensive testing prior to its use. For each test vehicle the B-52 carried, minor changes were made to the launch-panel operator's station. Built originally by the Boeing Company, the NASA B-52 is powered by eight Pratt & Whitney J57-19 turbojet engines, each of which produce 12,000 pounds of thrust. The aircraft's normal launch speed has been Mach 0.8 (about 530 miles per hour) and its normal drop altitude has been 40,000 to 45,000 feet. It is 156 feet long and has a wing span of 185 feet.

  10. Vibration and aeroelastic analysis of highly flexible HALE aircraft

    NASA Astrophysics Data System (ADS)

    Chang, Chong-Seok

    The highly flexible HALE (High Altitude Long Endurance) aircraft analysis methodology is of interest because early studies indicated that HALE aircraft might have different vibration and aeroelastic characteristics from those of conventional aircraft. Recently the computer code Nonlinear Aeroelastic Trim And Stability of HALE Aircraft (NATASHA) was developed under NASA sponsorship. NATASHA can predict the flight dynamics and aeroelastic behavior for HALE aircraft with a flying wing configuration. Further analysis improvements for NATASHA were required to extend its capability to the ground vibration test (GVT) environment and to both GVT and aeroelastic behavior of HALE aircraft with other configurations. First, the analysis methodology, based on geometrically exact fully intrinsic beam theory, was extended to treat other aircraft cofigurations. Conventional aircraft with flexible fuselage and tail can now be modeled by treating the aircraft as an assembly of beam elements. NATASHA is now applicable to any aircraft cofiguration that can be modeled this way. The intrinsic beam formulation, which is a fundamental structural modeling approach, is now capable of being applying to a structure consisting of multiple beams by relating the virtual displacements and rotations at points where two or more beam elements are connected to each other. Additional aspects are also considered in the analysis such as auxiliary elevator input in the horizontal tail and fuselage aerodynamics. Second, the modeling approach was extended to treat the GVT environment for HALE aircraft, which have highly flexible wings. GVT has its main purpose to provide modal characteristics for model validation. A bungee formulation was developed by the augmented Lagrangian method and coupled to the intrinsic beam formulation for the GVT modeling. After the coupling procedure, the whole formulation cannot be fully intrinsic because the geometric constraint by bungee cords makes the system statically

  11. Aircraft integrated design and analysis: A classroom experience

    NASA Technical Reports Server (NTRS)

    Weisshaar, Terrence A.

    1989-01-01

    AAE 451 is the capstone course required of all senior undergraduates in the School of Aeronautics and Astronautics at Purdue University. During the past year the first steps of a long evolutionary process were taken to change the content and expectations of this course. These changes are the result of the availability of advanced computational capabilities and sophisticated electronic media availability at Purdue. This presentation will describe both the long range objectives and this year's experience using the High Speed Commercial Transport design, the AIAA Long Duration Aircraft design and RPV design proposal as project objectives. The central goal of these efforts is to provide a user-friendly, computer-software-based environment to supplement traditional design course methodology. The Purdue University Computer Center (PUCC), the Engineering Computer Network (ECN) and stand-alone PC's are being used for this development. This year's accomplishments center primarily on aerodynamics software obtained from NASA/Langley and its integration into the classroom. Word processor capability for oral and written work and computer graphics were also blended into the course. A total of ten HSCT designs were generated, ranging from twin-fuselage aircraft, forward swept wing aircraft to the more traditional delta and double-delta wing aircraft. Four Long Duration Aircraft designs were submitted, together with one RPV design tailored for photographic surveillance.

  12. High energy radiation from aircraft-triggered lightning and thunderstorm

    NASA Astrophysics Data System (ADS)

    Kochkin, Pavlo; van Deursen, Alexander P. J.; de Boer, Alte I.; Bardet, Michiel; Boissin, Jean-François

    2016-04-01

    In-flight Lightning Strike Damage Assessment System (ILDAS http://ildas.nlr.nl/) was developed in an EU FP6 project to provide information on threat that lightning poses to aircraft. The system contains one E-field and eight H-field sensors distributed over the fuselage. It has recently been extended to include two LaBr3 scintillation detectors. The scintillation detectors are sensitive to x-ray photons above 30 keV. The entire system is installed on an A-350 aircraft. When triggered by lightning and digitizes data synchronously with 10 ns intervals. Twelve continuously monitoring photon energy channels were implemented for X-ray detectors operating at slower rate (15 ms, pulse counting). In spring of 2014 and 2015 the aircraft flew through thunderstorm cells recording the data from the sensors. Total of 93 lightning strikes to the aircraft are recorded. Eighteen of them are also detected by WWLLN network. One strike consists of six individual strokes within 200 ms that were all synchronously identified by WWLLN. The WWLLN inter-stroke distance is much larger than the aircraft movement. Three of these strokes generated X-ray bursts. One exceptionally bright X-ray pulse of more than 8 MeV has been detected in association with another strike; it probably saturated the detector's photomultiplier. Neither long gamma-ray glow, nor positron annihilation have been detected during the campaign. An explanation is sought in the typical altitude profile of these test flights.

  13. SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 2. Appendix A: Design study for a SLEEC actuation system

    NASA Technical Reports Server (NTRS)

    Thompson, D. S.

    1986-01-01

    The results are presented of a design feasibility study of a self-contained (powered) actuation system for a Shingle Lap Extendible Exit Cone (SLEEC) for Transportation System (STS). The evolution of the SLEEC actuation system design is reviewed, the final design concept is summarized, and the results of the detailed study of the final concept of the actuation system are treated. A conservative design using proven mechanical components was established as a major program priority. The final mechanical design has a very low development risk since the components, which consist of ballscrews, gearing, flexible shaft drives, and aircraft cables, have extensive aerospace applications and a history of proven reliability. The mathematical model studies have shown that little or no power is required to deploy the SLEEC actuation system because acceleration forces and internal pressure from the rocket plume provide the required energies. A speed control brake is incorporated in the design in order to control the rate of deployment.

  14. PIK-20 Aircraft in Flight

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This photo shows NASA's PIK-20E motor-glider sailplane during a research flight from the Ames-Dryden Flight Research Facility (later, the Dryden Flight Research Center), Edwards, California, in 1991. The PIK-20E was a sailplane flown at NASA's Ames-Dryden Flight Research Facility (now Dryden Flight Research Center, Edwards, California) beginning in 1981. The vehicle, bearing NASA tail number 803, was used as a research vehicle on projects calling for high lift-over-drag and low-speed performance. Later NASA used the PIK-20E to study the flow of fluids over the aircraft's surface at various speeds and angles of attack as part of a study of airflow efficiency over lifting surfaces. The single-seat aircraft was used to begin developing procedures for collecting sailplane glide performance data in a program carried out by Ames-Dryden. It was also used to study high-lift aerodynamics and laminar flow on high-lift airfoils. Built by Eiri-Avion in Finland, the PIK-20E is a sailplane with a two-cylinder 43-horsepower, retractable engine. It is made of carbon fiber with sandwich construction. In this unique configuration, it takes off and climbs to altitude on its own. After reaching the desired altitude, the engine is shut down and folded back into the fuselage and the aircraft is then operated as a conventional sailplane. Construction of the PIK-20E series was rather unusual. The factory used high-temperature epoxies cured in an autoclave, making the structure resistant to deformation with age. Unlike today's normal practice of laying glass over gelcoat in a mold, the PIK-20E was built without gelcoat. The finish is the result of smooth glass lay-up, a small amount of filler, and an acrylic enamel paint. The sailplane was 21.4 feet long and had a wingspan of 49.2 feet. It featured a wooden, fixed-pitch propeller, a roomy cockpit, wingtip wheels, and a steerable tailwheel.

  15. Nondestructive inspection of bonded composite doublers for aircraft

    NASA Astrophysics Data System (ADS)

    Roach, Dennis P.; Moore, David; Walkington, Phillip D.

    1996-11-01

    One of the major thrusts established under the FAA's National Aging Aircraft Research Program is to foster new technologies associated with civil aircraft maintenance. Recent DOD and other government developments in the use of bonded composite doublers on metal structures has supported the need for research and validation of such doubler applications on US certificated airplanes. Composite doubler technology is rapidly maturing and shows promise of cost savings on aging aircraft. While there have been numerous studies and military aircraft installations of composite doublers, the technology has not been certified for use on commercial aircraft. Before the use of composite doublers can be accepted by the civil aviation industry, it is imperative that methods be developed which can quickly and reliably assess the integrity of the doubler. In this study, a specific composite application was chosen on an L-1011 aircraft in order to focus the tasks on application and operation issues. Primary among inspection requirements for these doublers is the identification of disbonds, between the composite laminate and aluminum parent material, and delaminations in the composite laminate. Surveillance of cracks or corrosion in the inspection (NDI) method can inspect for every flaw type, therefore it is important to be aware of available NDI techniques and to properly address their capabilities and limitations. This paper reports on a series of NDI tests which have been conducted on laboratory test structures and on a fuselage section cut from a retired L-1011 aircraft. Specific challenges, unique to bonded composite doubler applications, will be highlighted. In order to quickly integrate this technology into existing aircraft maintenance depots, the use of conventional NDI, ultrasonics, x-ray, and eddy current, is stressed. The application of these NDI technique to composite doublers and the results from test specimens, which were loaded to provide a changing flaw profile, are

  16. LAP degradation product reflects plasma kallikrein-dependent TGF-β activation in patients with hepatic fibrosis.

    PubMed

    Hara, Mitsuko; Kirita, Akiko; Kondo, Wakako; Matsuura, Tomokazu; Nagatsuma, Keisuke; Dohmae, Naoshi; Ogawa, Shinji; Imajoh-Ohmi, Shinobu; Friedman, Scott L; Rifkin, Daniel B; Kojima, Soichi

    2014-01-01

    Byproducts of cytokine activation are sometimes useful as surrogate biomarkers for monitoring cytokine generation in patients. Transforming growth factor (TGF)-β plays a pivotal role in pathogenesis of hepatic fibrosis. TGF-β is produced as part of an inactive latent complex, in which the cytokine is trapped by its propeptide, the latency-associated protein (LAP). Therefore, to exert its biological activity, TGF-β must be released from the latent complex. Several proteases activate latent TGF-β by cutting LAP. We previously reported that Camostat Mesilate, a broad spectrum protease inhibitor, which is especially potent at inhibiting plasma kallikrein (PLK), prevented liver fibrosis in the porcine serum-induced liver fibrosis model in rats. We suggested that PLK may work as an activator of latent TGF-β during the pathogenesis of liver diseases in the animal models. However, it remained to be elucidated whether this activation mechanism also functions in fibrotic liver in patients. Here, we report that PLK cleaves LAP between R(58) and L(59) residues. We have produced monoclonal antibodies against two degradation products of LAP (LAP-DP) by PLK, and we have used these specific antibodies to immunostain LAP-DP in liver tissues from both fibrotic animals and patients. The N-terminal side LAP-DP ending at R(58) (R(58) LAP-DP) was detected in liver tissues, while the C-terminal side LAP-DP beginning at L(59) (L(59) LAP-DP) was not detectable. The R(58) LAP-DP was seen mostly in α-smooth muscle actin-positive activated stellate cells. These data suggest for the first time that the occurrence of a PLK-dependent TGF-β activation reaction in patients and indicates that the LAP-DP may be useful as a surrogate marker reflecting PLK-dependent TGF-β activation in fibrotic liver both in animal models and in patients. PMID:24877031

  17. Educating with Aircraft Models

    ERIC Educational Resources Information Center

    Steele, Hobie

    1976-01-01

    Described is utilization of aircraft models, model aircraft clubs, and model aircraft magazines to promote student interest in aerospace education. The addresses for clubs and magazines are included. (SL)

  18. Nacelle Integration to Reduce the Sonic Boom of Aircraft Designed to Cruise at Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    Mack, Robert J.

    1999-01-01

    An empirical method for integrating the engine nacelles on a wing-fuselage-fin(s) configuration has been described. This method is based on Whitham theory and Seebass and George sonic-boom minimization theory, With it, both reduced sonic-boom as well as high aerodynamic efficiency methods can be applied to the conceptual design of a supersonic-cruise aircraft. Two high-speed civil transport concepts were used as examples to illustrate the application of this engine-nacelle integration methodology: (1) a concept with engine nacelles mounted on the aft-fuselage, the HSCT-1OB; and (2) a concept with engine nacelles mounted under an extended-wing center section, the HSCT-11E. In both cases, the key to a significant reduction in the sonic-boom contribution from the engine nacelles was to use the F-function shape of the concept as a guide to move the nacelles further aft on the configuration.

  19. Development of Advanced Methods of Structural and Trajectory Analysis for Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Ardema, Mark D.

    1996-01-01

    In this report the author describes: (1) development of advanced methods of structural weight estimation, and (2) development of advanced methods of flight path optimization. A method of estimating the load-bearing fuselage weight and wing weight of transport aircraft based on fundamental structural principles has been developed. This method of weight estimation represents a compromise between the rapid assessment of component weight using empirical methods based on actual weights of existing aircraft and detailed, but time-consuming, analysis using the finite element method. The method was applied to eight existing subsonic transports for validation and correlation. Integration of the resulting computer program, PDCYL, has been made into the weights-calculating module of the AirCraft SYNThesis (ACSYNT) computer program. ACSYNT bas traditionally used only empirical weight estimation methods; PDCYL adds to ACSYNT a rapid, accurate means of assessing the fuselage and wing weights of unconventional aircraft. PDCYL also allows flexibility in the choice of structural concept, as well as a direct means of determining the impact of advanced materials on structural weight.

  20. Light Absorbing Particle (LAP) Measurements in the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Baumgardner, D.; Raga, G. B.; Anderson, B.; Diskin, G.; Sachse, G.; Kok, G.

    2003-01-01

    This viewgraph presentation covers the capabilities and design of the Single Particle Soot Photometer (SP-2), and reviews its role on the Sage III Ozone Loss Validation Experiment (SOLVE II) field campaign during 2003. On SOLVE II the SP-2 was carried into the Arctic onboard a DC-8 aircraft, in order to determine the size distribution of light-absorbing and non light-absorbing particles in the stratosphere. Graphs and tables relate some of the results from SOLVE II.

  1. The SOFIA aircraft and its modification

    NASA Astrophysics Data System (ADS)

    Kunz, Nans

    2003-02-01

    The primary focus of this paper is to describe the development of a highly modified aircraft that carries a twenty ton telescope to the stratosphere and then loiters at this desired altitude to act as the observatory platform and dome. When the aircraft has reached its nominal cruise condition of Mach 0.84 in the stratosphere, a large cavity door opens (the dome opens), exposing a large portion of the interior of the fuselage that contains the telescope optics directly to the Universe. The topics covered in this paper include: the relevant criteria and the evaluation process that resulted in the selection of a Boeing 747-SP, the evolution of the design concept, the description of the structural modification including the analysis methods and tools, the aerodynamic issues associated with an open port cavity and how they were addressed, and the aeroloads/ disturbances imparted to the telescope and how they were measured in the wind tunnel and extrapolated to full size. This paper is complementary to a previous paper presented at the 2000 Airborne Telescope Systems conference which describes the challenges associated with the development of the SOFIA Telescope. For completeness, this paper also provides a brief overview of the SOFIA project including the joint project arrangement between NASA and DLR, a top level overview of the requirements, and finally the current project status.

  2. Internal-flow systems for aircraft

    NASA Technical Reports Server (NTRS)

    Rogallo, F M

    1940-01-01

    An investigation has been made to determine efficient arrangements for an internal-flow system of an aircraft when such a system operates by itself or in combination with other flow systems. The investigation included a theoretical treatment of a problem and tests in the NACA 5-foot vertical wind tunnel of inlet and outlet openings in a flat plate and in a wing. When an internal-flow system tends to decrease the final velocity of it's wake, the results showed that it should be arranged in series with the propulsive system; the inlet opening should be located at a forward stagnation point; and the outlet opening should be so shaped and located as to recover the kinetic energy of the jet without increasing the drag of other portions of the aircraft. When an internal-flow system tends to increase the final velocity new b's wake, as does a propeller, location of the inlet opening in the boundary layer or in the wake of the wing or in the fuselage may be desirable.

  3. Damage criticality and inspection concerns of composite-metallic aircraft structures under blunt impact

    NASA Astrophysics Data System (ADS)

    Zou, D.; Haack, C.; Bishop, P.; Bezabeh, A.

    2015-04-01

    Composite aircraft structures such as fuselage and wings are subject to impact from many sources. Ground service equipment (GSE) vehicles are regarded as realistic sources of blunt impact damage, where the protective soft rubber is used. With the use of composite materials, blunt impact damage is of special interest, since potential significant structural damage may be barely visible or invisible on the structure's outer surface. Such impact can result in local or non-local damage, in terms of internal delamination in skin, interfacial delamination between stiffeners and skin, and fracture of internal reinforced component such as stringers and frames. The consequences of these events result in aircraft damage, delays, and financial cost to the industry. Therefore, it is necessary to understand the criticality of damage under this impact and provide reliable recommendations for safety and inspection technologies. This investigation concerns a composite-metallic 4-hat-stiffened and 5-frame panel, designed to represent a fuselage structure panel generic to the new generation of composite aircraft. The test fixtures were developed based on the correlation between finite element analyses of the panel model and the barrel model. Three static tests at certain amount of impact energy were performed, in order to improve the understanding of the influence of the variation in shear ties, and the added rotational stiffness. The results of this research demonstrated low velocity high mass impacts on composite aircraft fuselages beyond 82.1 kN of impact load, which may cause extensive internal structural damage without clear visual detectability on the external skin surface.

  4. Strength and Efficiency during Lap Joining molding of GMT-Sheet

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Woo; Kim, Hyoung-Seok; Lee, Dong-Gi

    2010-06-01

    In order to substitute and recycle the existing automobile parts for GMT-Sheet, researches on the effects of GMT-Sheet on the establishment of precise joining strength, joining condition that are lap length of joining part, compression ratio, and closure speed must be carried out but until now, there is almost no case of systematic researches on joint of GMT-Sheet. Therefore, as there are many obstacles in joining of GMT-Sheet molding products or in production of stable molding products, the researches on these issues are required. Because of this, it is reality that GMT-Sheet is only applied to parts of newly developed automobiles instead of substituting the existing automobile parts. In this study, materials with each different fiber content ratio and fiber orientation state were used in the study for decision of molding condition of GMT-Sheet and the condition of lap joining. Clarify joining strength and lap joining efficiency during high temperature. Compression press lap joining molding of GMT-Sheet and research data regarding to the lap length of joining part was presented. Thus, the purpose of this study is to contribute to the substitution of existing products as well as usage development in non-automobile field and also to find out precise dynamic characteristics as designing data of structures.

  5. Large-scale Advanced Prop-fan (LAP) high speed wind tunnel test report

    NASA Technical Reports Server (NTRS)

    Campbell, William A.; Wainauski, Harold S.; Arseneaux, Peter J.

    1988-01-01

    High Speed Wind Tunnel testing of the SR-7L Large Scale Advanced Prop-Fan (LAP) is reported. The LAP is a 2.74 meter (9.0 ft) diameter, 8-bladed tractor type rated for 4475 KW (6000 SHP) at 1698 rpm. It was designated and built by Hamilton Standard under contract to the NASA Lewis Research Center. The LAP employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Testing was conducted in the ONERA S1-MA Atmospheric Wind Tunnel in Modane, France. The test objectives were to confirm that the LAP is free from high speed classical flutter, determine the structural and aerodynamic response to angular inflow, measure blade surface pressures (static and dynamic) and evaluate the aerodynamic performance at various blade angles, rotational speeds and Mach numbers. The measured structural and aerodynamic performance of the LAP correlated well with analytical predictions thereby providing confidence in the computer prediction codes used for the design. There were no signs of classical flutter throughout all phases of the test up to and including the 0.84 maximum Mach number achieved. Steady and unsteady blade surface pressures were successfully measured for a wide range of Mach numbers, inflow angles, rotational speeds and blade angles. No barriers were discovered that would prevent proceeding with the PTA (Prop-Fan Test Assessment) Flight Test Program scheduled for early 1987.

  6. The Nuclear Envelope Protein, LAP1B, Is a Novel Protein Phosphatase 1 Substrate

    PubMed Central

    Santos, Mariana; Rebelo, Sandra; Van Kleeff, Paula J. M.; Kim, Connie E.; Dauer, William T.; Fardilha, Margarida; da Cruz e Silva, Odete A.; da Cruz e Silva, Edgar F.

    2013-01-01

    Protein phosphatase 1 (PP1) binding proteins are quintessential regulators, determining substrate specificity and defining subcellular localization and activity of the latter. Here, we describe a novel PP1 binding protein, the nuclear membrane protein lamina associated polypeptide 1B (LAP1B), which interacts with the DYT1 dystonia protein torsinA. The PP1 binding domain in LAP1B was here identified as the REVRF motif at amino acids 55-59. The LAP1B:PP1 complex can be immunoprecipitated from cells in culture and rat cortex and the complex was further validated by yeast co-transformations and blot overlay assays. PP1, which is enriched in the nucleus, binds to the N-terminal nuclear domain of LAP1B, as shown by immunocolocalization and domain specific binding studies. PP1 dephosphorylates LAP1B, confirming the physiological relevance of this interaction. These findings place PP1 at a key position to participate in the pathogenesis of DYT1 dystonia and related nuclear envelope-based diseases. PMID:24116158

  7. Numerical computation of transonic flow about wing-fuselage configurations on a vector computer

    NASA Technical Reports Server (NTRS)

    Thomas, S. D.; Holst, T. L.

    1983-01-01

    The transonic wing analysis code TWING, which uses the AF2 relaxation algorithm, has been vectorized to run on the Cray-1S computer. Vectorization of this code improved computational efficiency over that of the CDC 7600 computer by factors of 11 to 13. The improvement compares favorably with the prediction of a theoretical performance model. A convenient generalization now permits the treatment of rudimentary wing-fuselage combinations. Flow predictions for a transport configuration in both isolated-wing and wing-fuselage modes show the expected trends in shock strength and position when compared with wind-tunnel results. An isolated fighter wing is examined in terms of execution time on three different computers and in comparison with experimental data. The computational fluid dynamics code produced during this study is a careful union of an efficient three-dimensional, transonic, numerical algorithm and the vector features presently available on modern computers.

  8. STAGS Developments for Residual Strength Analysis Methods for Metallic Fuselage Structures

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Rose, Cheryl A.

    2014-01-01

    A summary of advances in the Structural Analysis of General Shells (STAGS) finite element code for the residual strength analysis of metallic fuselage structures, that were realized through collaboration between the structures group at NASA Langley, and Dr. Charles Rankin is presented. The majority of the advancements described were made in the 1990's under the NASA Airframe Structural Integrity Program (NASIP). Example results from studies that were conducted using the STAGS code to develop improved understanding of the nonlinear response of cracked fuselage structures subjected to combined loads are presented. An integrated residual strength analysis methodology for metallic structure that models crack growth to predict the effect of cracks on structural integrity is demonstrated

  9. Analysis, Design and Optimization of Non-Cylindrical Fuselage for Blended-Wing-Body (BWB) Vehicle

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, V.; Sobieszczanski-Sobieski, J.; Kosaka, I.; Quinn, G.; Charpentier, C.

    2002-01-01

    Initial results of an investigation towards finding an efficient non-cylindrical fuselage configuration for a conceptual blended-wing-body flight vehicle were presented. A simplified 2-D beam column analysis and optimization was performed first. Then a set of detailed finite element models of deep sandwich panel and ribbed shell construction concepts were analyzed and optimized. Generally these concepts with flat surfaces were found to be structurally inefficient to withstand internal pressure and resultant compressive loads simultaneously. Alternatively, a set of multi-bubble fuselage configuration concepts were developed for balancing internal cabin pressure load efficiently, through membrane stress in inner-stiffened shell and inter-cabin walls. An outer-ribbed shell was designed to prevent buckling due to external resultant compressive loads. Initial results from finite element analysis appear to be promising. These concepts should be developed further to exploit their inherent structurally efficiency.

  10. Effects of surface temperature and Reynolds number on heat transfer to the Shuttle Orbiter leeward fuselage

    NASA Technical Reports Server (NTRS)

    Bertin, J. J.; Goodrich, W. D.

    1976-01-01

    Heat-transfer data obtained at hypersonic shock tunnel conditions and three-dimensional flow field computations were used to study the influence of surface temperature and Reynolds number on the heating experienced by the leeward fuselage area of the Space Shuttle Orbiter configuration. The basic results of this study indicate that systematic variations in the average total enthalpy within a boundary layer (as obtained through controlled nonadiabatic processes) has an influence on the heat transfer to downstream areas which can be correlated; even in three-dimensional separated flow areas. Specifically, the average separated-flow Stanton number for the fuselage leeward surface is shown to be moderately dependent on the windward-wall to free-stream total temperature ratio.

  11. Coupled rotor/fuselage dynamic analysis of the AH-1G helicopter and correlation with flight vibrations data

    NASA Technical Reports Server (NTRS)

    Corrigan, J. C.; Cronkhite, J. D.; Dompka, R. V.; Perry, K. S.; Rogers, J. P.; Sadler, S. G.

    1989-01-01

    Under a research program designated Design Analysis Methods for VIBrationS (DAMVIBS), existing analytical methods are used for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM), which has been developed, extensively documented, and correlated with ground vibration test. One procedure that was used for predicting coupled rotor-fuselage vibrations using the advanced Rotorcraft Flight Simulation Program C81 and NASTRAN is summarized. Detailed descriptions of the analytical formulation of rotor dynamics equations, fuselage dynamic equations, coupling between the rotor and fuselage, and solutions to the total system of equations in C81 are included. Analytical predictions of hub shears for main rotor harmonics 2p, 4p, and 6p generated by C81 are used in conjunction with 2p OLS measured control loads and a 2p lateral tail rotor gearbox force, representing downwash impingement on the vertical fin, to excite the NASTRAN model. NASTRAN is then used to correlate with measured OLS flight test vibrations. Blade load comparisons predicted by C81 showed good agreement. In general, the fuselage vibration correlations show good agreement between anslysis and test in vibration response through 15 to 20 Hz.

  12. Formulas for the Stress Analysis of Circular Rings in a Monocoque Fuselage

    NASA Technical Reports Server (NTRS)

    Miller, Roy A; Wood, Karl D

    1933-01-01

    The formulas given in this report provide a simplified method for the stress-analysis of fuselage bulkheads that are approximately circular rings of uniform cross section. Complicated load systems acting on a ring can usually be resolved into simplified load systems; and formulas for moment, axial force, and shear for such simplified load systems are given in this report. Illustrative examples showing the use of this method in practical stress-analysis work are also included.

  13. Simulation of transonic viscous wing and wing-fuselage flows using zonal methods

    NASA Technical Reports Server (NTRS)

    Flores, Jolen

    1987-01-01

    The thin-layer Navier-Stokes equations are coupled with a zonal scheme (or domain-decomposition method) to develop the Transonic Navier-Stokes (TNS) wing-alone code. The TNS has a total of 4 zones and is extended to a total of 16 zones for the wing-fuselage version of the code. Results are compared on the Cray X-MP-48 and compared with experimental data.

  14. Navier-Stokes and potential theory solutions for ahelicopter fuselage and comparison with experiment

    NASA Technical Reports Server (NTRS)

    Chaffin, Mark S.; Berry, John D.

    1994-01-01

    A thin-layer Navier-Stokes code and a panel method code are used to predict the flow over a generic helicopter fuselage. The computational results are compared with pressure data at four experimental conditions. Both methods produce results that agree with the experimental pressure data. However, separation patterns and other viscous flow features from the Navier-Stokes code solution are shown that cannot be easily modeled with the panel method.

  15. Vertical drop test of a transport fuselage center section including the wheel wells

    NASA Technical Reports Server (NTRS)

    Williams, M. S.; Hayduk, R. J.

    1983-01-01

    A Boeing 707 fuselage section was drop tested to measure structural, seat, and anthropomorphic dummy response to vertical crash loads. The specimen had nominally zero pitch, roll and yaw at impact with a sink speed of 20 ft/sec. Results from this drop test and other drop tests of different transport sections will be used to prepare for a full-scale crash test of a B-720.

  16. Automatic computation of Euler-marching and subsonic grids for wing-fuselage configurations

    NASA Technical Reports Server (NTRS)

    Barger, Raymond L.; Adams, Mary S.; Krishnan, Ramki R.

    1994-01-01

    Algebraic procedures are described for the automatic generation of structured, single-block flow computation grids for relatively simple configurations (wing, fuselage, and fin). For supersonic flows, a quasi two-dimensional grid for Euler-marching codes is developed, and some sample results in graphical form are included. A type of grid for subsonic flow calculation is also described. The techniques are algebraic and are based on a generalization of the method of transfinite interpolation.

  17. Intrauterine infusion of latency-associated peptide (LAP) during early porcine pregnancy affects conceptus elongation and placental size.

    PubMed

    Massuto, Dana A; Hooper, R Neil; Kneese, Eric C; Johnson, Greg A; Ing, Nancy H; Weeks, Bradley R; Jaeger, Laurie A

    2010-03-01

    In the pig, transforming growth factor beta (TGFB), TGFB receptors (TGFBRs), and integrins are present during the peri-implantation period. Latency-associated peptide (LAP), a part of latent TGFB, can bind to integrin heterodimers via its Arg-Gly-Asp (RGD) sequence; therefore, ligand-receptor interactions between TGFB and TGFBRs, along with LAP and integrin heterodimers, may be functional in mediating events supporting conceptus elongation and attachment. With the use of surgically implantable osmotic pumps, we were able to maintain pregnancy with the aim of mechanistically altering in vivo receptor-ligand interactions involving TGFB with TGFBRs and LAP with integrins during porcine pregnancy. Day 9 pregnant gilts received intrauterine infusions of LAP-RGD, a recombinant mutant of LAP (LAP-RGE), or vehicle control and were ovariohysterectomized on Day 13 or 24 of pregnancy. We hypothesized that intrauterine infusion of LAP-RGD would decrease downstream signaling of TGFB while increasing LAP-integrin interactions and that net effect would enhance conceptus survival and attachment early in the peri-implantation period but possibly increase the chance of abnormal placentation later in pregnancy. Additionally, we hypothesized that infusion of LAP-RGE would disrupt TGFB signals but not alter integrin signaling, and thus the net result would be decreased conceptus survival and abnormal development. Unexpectedly, LAP-RGD intrauterine infusions resulted in a reduction of conceptus elongation, whereas infusions of LAP-RGE permitted implantation and placentation but resulted in larger fetal weight, allantois length, and allantoic fluid volume. Results suggest TGFB and integrins are contributing factors in the regulation of conceptus elongation and placental and fetal size. PMID:19906685

  18. Multi-Terrain Vertical Drop Tests of a Composite Fuselage Section

    NASA Technical Reports Server (NTRS)

    Kellas, Sotiris; Jackson, Karen E.

    2008-01-01

    A 5-ft-diameter composite fuselage section was retrofitted with four identical blocks of deployable honeycomb energy absorber and crash tested on two different surfaces: soft soil, and water. The drop tests were conducted at the 70-ft. drop tower at the Landing and Impact Research (LandIR) Facility of NASA Langley. Water drop tests were performed into a 15-ft-diameter pool of water that was approximately 42-in. deep. For the soft soil impact, a 15-ft-square container filled with fine-sifted, unpacked sand was located beneath the drop tower. All drop tests were vertical with a nominally flat attitude with respect to the impact surface. The measured impact velocities were 37.4, and 24.7-fps for soft soil and water, respectively. A fuselage section without energy absorbers was also drop tested onto water to provide a datum for comparison with the test, which included energy absorbers. In order to facilitate this type of comparison and to ensure fuselage survivability for the no-energy-absorber case, the velocity of the water impact tests was restricted to 25-fps nominal. While all tests described in this paper were limited to vertical impact velocities, the implications and design challenges of utilizing external energy absorbers during combined forward and vertical impact velocities are discussed. The design, testing and selection of a honeycomb cover, which was required in soft surface and water impacts to transmit the load into the honeycomb cell walls, is also presented.

  19. Hybrid Wing-Body Pressurized Fuselage and Bulkhead, Design and Optimization

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, Vivek

    2013-01-01

    The structural weight reduction of a pressurized Hybrid Wing-Body (HWB) fuselage is a serious challenge. Hence, research and development are presently being continued at NASA under the Environmentally Responsible Aviation (ERA) and Subsonic Fixed Wing (SFW) projects in collaboration with the Boeing Company, Huntington Beach and Air Force Research Laboratory (AFRL). In this paper, a structural analysis of the HWB fuselage and bulkhead panels is presented, with the objectives of design improvement and structural weight reduction. First, orthotropic plate theories for sizing, and equivalent plate analysis with appropriate simplification are considered. Then parametric finite-element analysis of a fuselage section and bulkhead are conducted using advanced stitched composite structural concepts, which are presently being developed at Boeing for pressurized HWB flight vehicles. With this advanced stiffened-shell design, structural weights are computed and compared to the thick sandwich, vaulted-ribbed-shell, and multi-bubble stiffened-shell structural concepts that had been studied previously. The analytical and numerical results are discussed to assess the overall weight/strength advantages.

  20. Sound Transmission Loss Prediction of the Composite Fuselage with Different Methods

    NASA Astrophysics Data System (ADS)

    Yuan, Chongxin; Bergsma, Otto; Beukers, Adriaan

    2012-12-01

    Increase of sound transmission loss(TL) of the fuselage is vital to build a comfortable cabin environment. In this paper, to find a convenient and accurate means for predicting the fuselage TL, the fuselage is modeled as a composite cylinder, and its TL is predicted with the analytical, the statistic energy analysis (SEA) and the hybrid FE&SEA method. The TL results predicted by the three methods are compared to each other and they show good agreement, but in terms of model building the SEA method is the most convenient one. Therefore, the parameters including the layup, the materials, the geometry, and the structure type are studied with the SEA method. It is observed that asymmetric laminates provide better sound insulation in general. It is further found that glass fiber laminates result in the best sound insulation as compared with graphite and aramid fiber laminates. In addition, the cylinder length has little influence on the sound insulation, while an increase of the radius considerably reduces the TL at low frequencies. Finally, by a comparison among an unstiffened laminate, a sandwich panel and a stiffened panel, the sandwich panel presents the largest TL at high frequencies and the stiffened panel demonstrates the poorest sound insulation at all frequencies.