Science.gov

Sample records for active landing gear

  1. Active control landing gear for ground load alleviation

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Morris, D. L.

    1985-01-01

    Results of analytical and experimental investigations of a series-hydraulic active control landing gear show that such a gear is feasible when using existing hardware and is very effective in reducing loads, relative to those generated by a conventional (passive year) gear, transmitted to the airframe during ground operations. Analytical results obtained from an active gear, flexible aircraft, take-off and landing analysis are in good agreement with experimental data and indicate that the analysis is a valid tool for study and initial design of series-hydraulic active control landing gears. An analytical study of a series-hydraulic active control main landing gear on an operational supersonic airplane shows that the active gear has the potential for improving the dynamic response of the aircraft and significantly reducing structural fatigue damage during ground operations.

  2. Experimental investigation of active loads control for aircraft landing gear

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Dreher, R. C.

    1982-01-01

    Aircraft dynamic loads and vibrations resulting from landing impact and from runway and taxiway unevenness are recognized as significant in causing fatigue damage, dynamic stress on the airframe, crew and passenger discomfort, and reduction of the pilot's ability to control the aircraft during ground operations. One potential method for improving operational characteistics of aircraft on the ground is the application of active control technology to the landing gears to reduce ground loads applied to the airframe. An experimental investigation was conducted which simulated the landing dynamics of a light airplane to determine the feasibility and potential of a series hydraulic active control main landing gear. The experiments involved a passive gear and an active control gear. Results of this investigation show that a series hydraulically controlled gear is feasible and that such a gear is very effective in reducing the loads transmitted by the gear to the airframe during ground operations.

  3. 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.

  4. Flightworthy active control landing gear for a supersonic aircraft

    NASA Technical Reports Server (NTRS)

    Ross, I.

    1980-01-01

    A flightworthy active control landing gear system for a supersonic aircraft was designed to minimize aircraft loads during takeoff, impact, rollout, and taxi. The design consists of hydromechanical modifications to the existing gear and the development of a fail-safe electronic controller. analytical RESULTS INDICATE that for an aircraft sink rate of 0.914 m/sec (3 ft/sec) the system achieves a peak load reduction of 36% during landing impact.

  5. AGFATL- ACTIVE GEAR FLEXIBLE AIRCRAFT TAKEOFF AND LANDING ANALYSIS

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.

    1994-01-01

    The Active Gear, Flexible Aircraft Takeoff and Landing Analysis program, AGFATL, was developed to provide a complete simulation of the aircraft takeoff and landing dynamics problem. AGFATL can represent an airplane either as a rigid body with six degrees of freedom or as a flexible body with multiple degrees of freedom. The airframe flexibility is represented by the superposition of up to twenty free vibration modes on the rigid-body motions. The analysis includes maneuver logic and autopilots programmed to control the aircraft during glide slope, flare, landing, and takeoff. The program is modular so that performance of the aircraft in flight and during landing and ground maneuvers can be studied separately or in combination. A program restart capability is included in AGFATL. Effects simulated in the AGFATL program include: (1) flexible aircraft control and performance during glide slope, flare, landing roll, and takeoff roll under conditions of changing winds, engine failures, brake failures, control system failures, strut failures, restrictions due to runway length, and control variable limits and time lags; (2) landing gear loads and dynamics for up to five gears; (3) single and multiple engines (maximum of four) including selective engine reversing and failure; (4) drag chute and spoiler effects; (5) wheel braking (including skid-control) and selective brake failure; (6) aerodynamic ground effects; (7) aircraft carrier operations; (8) inclined runways and runway perturbations; (9) flexible or rigid airframes; 10) rudder and nose gear steering; and 11) actively controlled landing gear shock struts. Input to the AGFATL program includes data which describe runway roughness; vehicle geometry, flexibility and aerodynamic characteristics; landing gear(s); propulsion; and initial conditions such as attitude, attitude change rates, and velocities. AGFATL performs a time integration of the equations of motion and outputs comprehensive information on the airframe

  6. On Landing Gear Stresses

    NASA Technical Reports Server (NTRS)

    Gentric, A.

    1956-01-01

    Information on landing gear stresses is presented on the following: vibratory phenomena, tangential forces applied to landing gear, fore and aft oscillations of landing gears, examples of fatigue failures, vibration calculations, and improvement of existing test equipment.

  7. Active control landing gear for ground loads alleviation

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.

    1985-01-01

    An active landing gear has been created by connecting the hydraulic piston in an oleo strut to a hydraulic supply. A controller modulates the pressure in the oleo to achieve the desired dynamic characteristics. Tests on ground rigs (documented by a film) have demonstrated the successful alleviation of induced structural ground loads and the next step will be a flight test using a fighter aircraft.

  8. An electronic control for an electrohydraulic active control landing gear for the F-4 aircraft

    NASA Technical Reports Server (NTRS)

    Ross, I.

    1982-01-01

    A controller for an electrohydraulic active control landing gear was developed for the F-4 aircraft. A controller was modified for this application. Simulation results indicate that during landing and rollout over repaired bomb craters the active gear effects a force reduction, relative to the passive gear, or approximately 70%.

  9. An electric control for an electrohydraulic active control aircraft landing gear

    NASA Technical Reports Server (NTRS)

    Ross, I.; Edson, R.

    1979-01-01

    An electronic controller for an electrohydraulic active control aircraft landing gear was developed. Drop tests of a modified gear from a 2722 Kg (6000 lbm) class of airplane were conducted to illustrate controller performance. The results indicate that the active gear effects a force reduction, relative to that of the passive gear, from 9 to 31 percent depending on the aircraft sink speed and the static gear pressure.

  10. Experimental and analytical investigation of active loads control for aircraft landing gear

    NASA Technical Reports Server (NTRS)

    Morris, D. L.; Mcgehee, J. R.

    1983-01-01

    A series hydraulic, active loads control main landing gear from a light, twin-engine civil aircraft was investigated. Tests included landing impact and traversal of simulated runway roughness. It is shown that the active gear is feasible and very effective in reducing the force transmitted to the airframe. Preliminary validation of a multidegree of freedom active gear flexible airframe takeoff and landing analysis computer program, which may be used as a design tool for active gear systems, is accomplished by comparing experimental and computed data for the passive and active gears.

  11. Landing gear noise attenuation

    NASA Technical Reports Server (NTRS)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  12. F-106B airplane active control landing gear drop test performance

    NASA Technical Reports Server (NTRS)

    Howell, William E.; Mccehee, John R.; Daugherty, Robert H.; Vogler, William A.

    1990-01-01

    Aircraft dynamic loads and vibrations resulting from landing impact and from runway and taxiway unevenness are recognized as significant factors in causing fatigue damage, dynamic stress on the airframe, crew and passenger discomfort, and reduction of the pilot's ability to control the aircraft during ground operations. One potential method for improving operational characteristics of aircraft on the ground is the application of active-control technology to the landing gears to reduce ground loads applied to the airframe. An experimental investigation was conducted on series-hydraulic active control nose gear. The experiments involved testing the gear in both passive and active control modes. Results of this investigation show that a series-hydraulic active-control gear is feasible and that such a gear is effective in reducing the loads transmitted by the gear to the airframe during ground operations.

  13. F-106B airplane active control landing gear drop test performance

    NASA Technical Reports Server (NTRS)

    Howell, William E.; Mcgehee, John R.; Daugherty, Robert H.; Vogler, William A.

    1990-01-01

    Aircraft dynamic loads and vibrations resulting from landing impact and from runway and taxiway unevenness are recognized as significant factors in causing fatigue damage, dynamic stress on the airframe, crew and passenger discomfort, and reduction of the pilot's ability to control the aircraft during ground operations. One potential method for improving operational characteristics of aircraft on the ground is the application of active control technology to the landing gears to reduce ground loads applied to the airframe. An experimental investigation was conducted on series-hydraulic active control nose gear. The experiments involved testing the gear in both passive and active control modes. Results of this investigation show that a series-hydraulic active control gear is feasible and that such a gear is effective in reducing the loads transmitted by the gear to the airframe during ground operations.

  14. An electrorheologically controlled semi-active landing gear

    NASA Technical Reports Server (NTRS)

    Lou, Zheng; Ervin, Robert D.; Winkler, Christopher B.; Filisko, Frank E.

    1993-01-01

    This study is to explore the application of electrorheology (ER) to the real-time control of damping forces that are transmitted through the nose landing gear for an F-106B aircraft. The main part of the landing gear is a strut that consists of a pneumatic spring and an ER controlled damper that is situatted on the strut centerline and applies a force directly opposing the vertical displacement of the nose wheel. The damping element rotates in response to strut displacement, employing a co-axial arrangement of stator and rotor plates connected to the opposing electrodes in the control circuit. The vertical displacement is conveted into rotation of the damper through a screw-nut mechanism. The ER fluid between the electrodes is thus engaged in shear along circumferential lines of action. This design results in a fast time response and a high ratio of strut forces achieved under Er-vs. zero-field control. Compact size and simplicity in fabrication are also attained. The analysis shows that when using an ER fluid of a yield stress of 7kPa, the energy absorption efficiency of the landing gear can reach almost 100% at various sink rates.

  15. Summary of NASA landing-gear research

    NASA Technical Reports Server (NTRS)

    Fisher, B. D.; Sleeper, R. K.; Stubbs, S. M.

    1978-01-01

    This paper presents a brief summary of the airplane landing gear research underway at NASA. The technology areas include: ground handling simulator, antiskid braking systems, space shuttle nose-gear shimmy, active control landing gear, wire brush skid landing gear, air cushion landing systems, tire/surface friction characteristics, tire mechanical properties, tire-tread materials, powered wheels for taxiing, and crosswind landing gear. This paper deals mainly with the programs on tire-tread materials, powered wheel taxiing, air cushion landing systems, and crosswind landing gear research with particular emphasis on previously unreported results of recently completed flight tests. Work in the remaining areas is only mentioned.

  16. Modeling and Validation of a Navy A6-Intruder Actively Controlled Landing Gear System

    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 by using actively controlled landing gear. 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 are used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

  17. Validation of an Active Gear, Flexible Aircraft Take-off and Landing analysis (AGFATL)

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.

    1984-01-01

    The results of an analytical investigation using a computer program for active gear, flexible aircraft take off and landing analysis (AGFATL) are compared with experimental data from shaker tests, drop tests, and simulated landing tests to validate the AGFATL computer program. Comparison of experimental and analytical responses for both passive and active gears indicates good agreement for shaker tests and drop tests. For the simulated landing tests, the passive and active gears were influenced by large strut binding friction forces. The inclusion of these undefined forces in the analytical simulations was difficult, and consequently only fair to good agreement was obtained. An assessment of the results from the investigation indicates that the AGFATL computer program is a valid tool for the study and initial design of series hydraulic active control landing gear systems.

  18. Improved aircraft dynamic response and fatigue life during ground operations using an active control landing gear system

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Carden, H. D.; Edson, R.

    1978-01-01

    A three-degree-of-freedom aircraft landing analysis incorporating a series-hydraulic active control main landing gear has been developed and verified using preliminary experimental data from drop tests of a modified main landing gear from a 2722 kg (6000 lbm) class of airplane. The verified analysis was also employed to predict the landing dynamics of a supersonic research airplane with an active control main landing gear system. The results of this investigation have shown that this type of active gear is feasible and indicate a potential for improving airplane dynamic response and reducing structural fatigue damage during ground operations by approximately 90% relative to that incurred with the passive gear.

  19. Aircraft landing gear systems

    NASA Technical Reports Server (NTRS)

    Tanner, John A. (Editor)

    1990-01-01

    Topics presented include the laboratory simulation of landing gear pitch-plane dynamics, a summary of recent aircraft/ground vehicle friction measurement tests, some recent aircraft tire thermal studies, and an evaluation of critical speeds in high-speed aircraft. Also presented are a review of NASA antiskid braking research, titanium matrix composite landing gear development, the current methods and perspective of aircraft flotation analysis, the flow rate and trajectory of water spray produced by an aircraft tire, and spin-up studies of the Space Shuttle Orbiter main gear tire.

  20. Improvements to the FATOLA computer program including added actively controlled landing gear subroutines

    NASA Technical Reports Server (NTRS)

    Mall, G. H.

    1983-01-01

    Modifications to a multi-degree-of-freedom flexible aircraft take-off and landing analysis (FATOLA) computer program, including a provision for actively controlled landing gears to expand the programs simulation capabilities, are presented. Supplemental instructions for preparation of data and for use of the modified program are included.

  1. Semi-active control of a landing gear system using magnetrorheological damper

    NASA Astrophysics Data System (ADS)

    Nam, Y. J.; Park, M. K.; Choi, J. W.; Yamane, R.

    2007-12-01

    This paper is concerned with the applicability of the developed MR damper to the landing gear system for the attenuating undesired shock and vibration in the landing and taxing phases. First of all, the experimental model of the MR damper is derived based on the results of performance evaluations. Next, a simplified skyhook controller, which is one of the most straightforward, but effective approaches for improving ride comport in vehicles with active suspensions, is formulated. Finally, the vibration control performances of the landing gear system using the MR damper are theoretically evaluated in the landing phase of the aircraft. A series of simulation analyses show that the proposed MR damper with the skyhook controller is effective for suppressing undesired vibration of the aircraft body.

  2. Application of active control landing gear technology to the A-10 aircraft

    NASA Technical Reports Server (NTRS)

    Ross, I.; Edson, R.

    1983-01-01

    Two concepts which reduce the A-10 aircraft's wing/gear interface forces as a result of applying active control technology to the main landing gear are described. In the first concept, referred to as the alternate concept a servovalve in a closed pressure control loop configuration effectively varies the size of the third stage spool valve orifice which is embedded in the strut. This action allows the internal energy in the strut to shunt hydraulic flow around the metering orifice. The command signal to the loop is reference strut pressure which is compared to the measured strut pressure, the difference being the loop error. Thus, the loop effectively varies the spool valve orifice size to maintain the strut pressure, and therefore minimizes the wing/gear interface force referenced.

  3. An Overview of Landing Gear Dynamics

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.

    1999-01-01

    One of the problems facing the aircraft community is landing gear dynamics, especially shimmy and brake-induced vibration. Shimmy and brake-induced vibrations can lead to accidents due to excessive wear and shortened life of gear parts and contribute to pilot and passenger discomfort. To increase understanding of these problems, a literature survey was performed. The major focus is on work from the last ten years. Some older publications are included to understand the longevity of the problem and the background from earlier researchers. The literature survey includes analyses, testing, modeling, and simulation of aircraft landing gear; and experimental validation and characterization of shimmy and brake-induced vibration of aircraft landing gear. The paper presents an overview of the problem, background information, and a history of landing gear dynamics problems and solutions. Based on the survey an assessment and recommendations of the most critically needed enhancements to the state of the art will be presented. The status of Langley work contributing to this activity will be given.

  4. High-speed T-38A landing gear extension loads

    NASA Technical Reports Server (NTRS)

    Schmitt, A. L.

    1980-01-01

    Testing of T-38A landing gear extension at high speed and high altitude is described. The mechanisms are shown together with peak hydraulic pressure data during landing gear deployment with active and inactive strut door flaps. Results of strain gage measurements of stress on various structural members are included.

  5. Topics in landing gear dynamics research at NASA Langley

    NASA Technical Reports Server (NTRS)

    Mccomb, H. G., Jr.; Tanner, J. A.

    1986-01-01

    Four topics in landing gear dynamics are discussed. Three of these topics are subjects of recent research: tilt steering phenomenon, water spray ingestion on flooded runways, and actively controlled landing gear. The fourth topic is a description of a major facility recently enhanced in capability.

  6. Analysis of Landing-Gear Behavior

    NASA Technical Reports Server (NTRS)

    Milwitzky, Benjamin; Cook, Francis E

    1953-01-01

    This report presents a theoretical study of the behavior of the conventional type of oleo-pneumatic landing gear during the process of landing impact. The basic analysis is presented in a general form and treats the motions of the landing gear prior to and subsequent to the beginning of shock-strut deflection. The applicability of the analysis to actual landing gears has been investigated for the particular case of a vertical landing gear in the absence of drag loads by comparing calculated results with experimental drop-test data for impacts with and without tire bottoming. The calculated behavior of the landing gear was found to be in good agreement with the drop-test data.

  7. NASA Orbiter Extended Nose Landing Gear

    NASA Technical Reports Server (NTRS)

    King, Steven R.; Jensen, Scott A.; Hansen, Christopher P.

    1999-01-01

    This paper discusses the design, development, test, and evaluation of a prototype Extended Nose Landing Gear (ENLG) for NASA's Space Shuttle orbiters. The ENLG is a proposed orbiter modification developed in-house at NASA's Johnson Space Center (JSC) by a joint government/industry team. It increases the orbiter's nose landing gear (NLG) length, thereby changing the vehicle's angle of attack during rollout, which lowers the aerodynamic forces on the vehicle. This, in combination with a dynamic elevon change, will lower the loads on the orbiter's main landing gear (MLG). The extension is accomplished by adding a telescoping section to the current NLG strut that will be pneumatically extended during NLG deployment.

  8. 14 CFR 25.1515 - Landing gear speeds.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Landing gear speeds. 25.1515 Section 25... Limitations § 25.1515 Landing gear speeds. (a) The established landing gear operating speed or speeds, V LO, may not exceed the speed at which it is safe both to extend and to retract the landing gear,...

  9. 14 CFR 25.1515 - Landing gear speeds.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Landing gear speeds. 25.1515 Section 25... Limitations § 25.1515 Landing gear speeds. (a) The established landing gear operating speed or speeds, V LO, may not exceed the speed at which it is safe both to extend and to retract the landing gear,...

  10. 14 CFR 25.1515 - Landing gear speeds.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing gear speeds. 25.1515 Section 25... Limitations § 25.1515 Landing gear speeds. (a) The established landing gear operating speed or speeds, V LO, may not exceed the speed at which it is safe both to extend and to retract the landing gear,...

  11. 14 CFR 25.1515 - Landing gear speeds.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Landing gear speeds. 25.1515 Section 25... Limitations § 25.1515 Landing gear speeds. (a) The established landing gear operating speed or speeds, V LO, may not exceed the speed at which it is safe both to extend and to retract the landing gear,...

  12. 14 CFR 25.1515 - Landing gear speeds.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Landing gear speeds. 25.1515 Section 25... Limitations § 25.1515 Landing gear speeds. (a) The established landing gear operating speed or speeds, V LO, may not exceed the speed at which it is safe both to extend and to retract the landing gear,...

  13. X-38 Landing Gear Skid Test Report

    NASA Technical Reports Server (NTRS)

    Gafka, George K.; Daugherty, Robert H.

    2000-01-01

    NASA incorporates skid-equipped landing gear on its series of X-38 flight test vehicles. The X-38 test program is the proving ground for the Crew Return Vehicle (CRV) a gliding parafoil-equipped vehicle designed to land at relatively low speeds. The skid-equipped landing gear is designed to attenuate the vertical landing energy of the vehicle at touchdown using crushable materials within the struts themselves. The vehicle then slides out as the vehicle horizontal energy is dissipated through the skids. A series of tests was conducted at Edwards Airforce Base (EAFB) in an attempt to quantify the drag force produced while "dragging" various X-38 landing gear skids across lakebed regions of varying surface properties. These data were then used to calculate coefficients of friction for each condition. Coefficient of friction information is critical for landing analyses as well as for landing gear load and interface load analysis. The skid specimens included full- and sub-scale V201 (space test vehicle) nose and main gear designs, a V131/V 132 (atmospheric flight test vehicles) main gear skid (actual flight hardware), and a newly modified, full-scale V201 nose -ear skid with substantially increased edge curvature as compared to its original design. Results of the testing are discussed along with comments on the relative importance of various parameters that influence skid stability and other dynamic behavior.

  14. Empirical Prediction of Aircraft Landing Gear Noise

    NASA Technical Reports Server (NTRS)

    Golub, Robert A. (Technical Monitor); Guo, Yue-Ping

    2005-01-01

    This report documents a semi-empirical/semi-analytical method for landing gear noise prediction. The method is based on scaling laws of the theory of aerodynamic noise generation and correlation of these scaling laws with current available test data. The former gives the method a sound theoretical foundation and the latter quantitatively determines the relations between the parameters of the landing gear assembly and the far field noise, enabling practical predictions of aircraft landing gear noise, both for parametric trends and for absolute noise levels. The prediction model is validated by wind tunnel test data for an isolated Boeing 737 landing gear and by flight data for the Boeing 777 airplane. In both cases, the predictions agree well with data, both in parametric trends and in absolute noise levels.

  15. An Overview of Landing Gear Dynamics

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.

    1999-01-01

    One of the problems facing the aircraft community is landing gear dynamics, especially shimmy and brake-induced vibration. Although neither shimmy nor brake-induced vibrations are usually catastrophic, they can lead to accidents due to excessive wear and shortened life of gear parts and contribute to pilot and passenger discomfort. Recently, NASA has initiated an effort to increase the safety of air travel by reducing the number of accidents by a factor of five in ten years. This safety initiative has spurred an increased interest in improving landing gear design to minimize shimmy and brake-induced vibration that are still largely misunderstood phenomena. In order to increase the understanding of these problems, a literature survey was performed. The major focus of the paper is to summarize work documented from the last ten years to highlight the latest efforts in solving these vibration problems. Older publications are included to understand the longevity of the problem and the findings from earlier researchers. The literature survey revealed a variety of analyses, testing, modeling, and simulation of aircraft landing gear. Experimental validation and characterization of shimmy and brake-induced vibration of aircraft landing gear are also reported. This paper presents an overview of the problem documented in the references together with a history of landing gear dynamic problems and solutions. Based on the assessment of this survey, recommendations of the most critically needed enhancements to the state of the art are given.

  16. Analytical investigation of the landing dynamics of a large airplane with a load-control system in the main landing gear

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.; Carden, H. D.

    1979-01-01

    The results of an evaluation of an active load-control landing gear computer program (ACOLAG) for predicting the landing dynamics of airplanes with passive and active main gears are presented. ACOLAG was used in an analytical investigation of the landing dynamics of a large airplane with both passive and active main gears. It was concluded that the program is valid for predicting the landing dynamics of airplanes with both passive and active main gears. It was shown that the active gear reduces airframe-gear forces and airplane motions following initial impact, and has the potential for significant reductions in structural fatigue damage relative to that which occurs with the passive gear.

  17. 14 CFR 23.477 - Landing gear arrangement.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Landing gear arrangement. 23.477 Section 23....477 Landing gear arrangement. Sections 23.479 through 23.483, or the conditions in appendix C, apply to airplanes with conventional arrangements of main and nose gear, or main and tail gear....

  18. 14 CFR 23.477 - Landing gear arrangement.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Landing gear arrangement. 23.477 Section 23....477 Landing gear arrangement. Sections 23.479 through 23.483, or the conditions in appendix C, apply to airplanes with conventional arrangements of main and nose gear, or main and tail gear....

  19. 14 CFR 23.477 - Landing gear arrangement.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing gear arrangement. 23.477 Section 23....477 Landing gear arrangement. Sections 23.479 through 23.483, or the conditions in appendix C, apply to airplanes with conventional arrangements of main and nose gear, or main and tail gear....

  20. 14 CFR 23.477 - Landing gear arrangement.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Landing gear arrangement. 23.477 Section 23....477 Landing gear arrangement. Sections 23.479 through 23.483, or the conditions in appendix C, apply to airplanes with conventional arrangements of main and nose gear, or main and tail gear....

  1. 14 CFR 23.477 - Landing gear arrangement.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Landing gear arrangement. 23.477 Section 23....477 Landing gear arrangement. Sections 23.479 through 23.483, or the conditions in appendix C, apply to airplanes with conventional arrangements of main and nose gear, or main and tail gear....

  2. Magneto-rheological (MR) damper for landing gear system

    NASA Astrophysics Data System (ADS)

    Khani, Mahboubeh

    2010-11-01

    Depending on the different sink speeds, angles of attack and masses; aircraft landing gears could face a wide range of impact conditions which may possibly cause structural damage or failure. Thus, in hard landing scenarios, the landing gear must absorb sufficient energy in order to minimize dynamic stress on the aircraft airframe. Semi-active control systems are the recent potential solutions to overcome these limitations. Among semi-active control strategies, those based on smart fluids such as magneto-rheological (MR) fluids have received recent attraction as their rheological properties can be continuously controlled using magnetic or electric field and they are not sensitive to the contaminants and the temperature variation and also require lower powers. This thesis focuses on modeling of a MR damper for landing gear system and analysis of semi-active controller to attenuate dynamic load and landing impact. First, passive landing gear of a Navy aircraft is modeled and the forces associated with the shock strut are formulated. The passive shock strut is then integrated with a MR valve to design MR shock strut. Here, MR shock strut is integrated with the landing gear system modeled as the 2DOF system and governing equations of motion are derived in order to simulate the dynamics of the system under different impact conditions. Subsequently the inverse model of the MR shock strut relating MR yield stress to the MR shock strut force and strut velocity is formulated. Using the developed governing equations and inverse model, a PID controller is formulated to reduce the acceleration of the system. Controlled performance of the simulated MR landing gear system is demonstrated and compared with that of passive system.

  3. 14 CFR 29.477 - Landing gear arrangement.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Landing gear arrangement. 29.477 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.477 Landing gear arrangement. Sections 29.235, 29.479 through 29.485, and 29.493 apply to landing gear with two wheels aft,...

  4. 14 CFR 29.477 - Landing gear arrangement.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Landing gear arrangement. 29.477 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.477 Landing gear arrangement. Sections 29.235, 29.479 through 29.485, and 29.493 apply to landing gear with two wheels aft,...

  5. 14 CFR 29.477 - Landing gear arrangement.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Landing gear arrangement. 29.477 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.477 Landing gear arrangement. Sections 29.235, 29.479 through 29.485, and 29.493 apply to landing gear with two wheels aft,...

  6. 14 CFR 25.483 - One-gear landing conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false One-gear landing conditions. 25.483 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.483 One-gear landing conditions. For the one-gear landing conditions, the airplane is assumed to be in the level attitude and...

  7. 14 CFR 25.483 - One-gear landing conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false One-gear landing conditions. 25.483 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.483 One-gear landing conditions. For the one-gear landing conditions, the airplane is assumed to be in the level attitude and...

  8. 14 CFR 29.477 - Landing gear arrangement.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Landing gear arrangement. 29.477 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.477 Landing gear arrangement. Sections 29.235, 29.479 through 29.485, and 29.493 apply to landing gear with two wheels aft,...

  9. 14 CFR 29.477 - Landing gear arrangement.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing gear arrangement. 29.477 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.477 Landing gear arrangement. Sections 29.235, 29.479 through 29.485, and 29.493 apply to landing gear with two wheels aft,...

  10. 14 CFR 27.477 - Landing gear arrangement.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Landing gear arrangement. 27.477 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.477 Landing gear arrangement. Sections 27.235, 27.479 through 27.485, and 27.493 apply to landing gear with two wheels aft,...

  11. 14 CFR 25.483 - One-gear landing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false One-gear landing conditions. 25.483 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.483 One-gear landing conditions. For the one-gear landing conditions, the airplane is assumed to be in the level attitude and...

  12. 14 CFR 27.477 - Landing gear arrangement.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Landing gear arrangement. 27.477 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.477 Landing gear arrangement. Sections 27.235, 27.479 through 27.485, and 27.493 apply to landing gear with two wheels aft,...

  13. 14 CFR 27.477 - Landing gear arrangement.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Landing gear arrangement. 27.477 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.477 Landing gear arrangement. Sections 27.235, 27.479 through 27.485, and 27.493 apply to landing gear with two wheels aft,...

  14. 14 CFR 25.483 - One-gear landing conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false One-gear landing conditions. 25.483 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.483 One-gear landing conditions. For the one-gear landing conditions, the airplane is assumed to be in the level attitude and...

  15. 14 CFR 27.477 - Landing gear arrangement.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing gear arrangement. 27.477 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.477 Landing gear arrangement. Sections 27.235, 27.479 through 27.485, and 27.493 apply to landing gear with two wheels aft,...

  16. 14 CFR 27.477 - Landing gear arrangement.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Landing gear arrangement. 27.477 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.477 Landing gear arrangement. Sections 27.235, 27.479 through 27.485, and 27.493 apply to landing gear with two wheels aft,...

  17. Apollo experience report: Lunar module landing gear subsystem

    NASA Technical Reports Server (NTRS)

    Rogers, W. F.

    1972-01-01

    The development of the lunar module landing gear subsystem through the Apollo 11 lunar landing mission is presented. The landing gear design evolved from the design requirement, which had to satisfy the structural, mechanical, and landing performance constraints of the vehicle. Extensive analyses and tests were undertaken to verify the design adequacy. Techniques of the landing performance analysis served as a primary tool in developing the subsystem hardware and in determining the adequacy of the landing gear for toppling stability and energy absorption. The successful Apollo 11 lunar landing mission provided the first opportunity for a complete flight test of the landing gear under both natural and induced environments.

  18. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

    A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

  19. 14 CFR 25.477 - Landing gear arrangement.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Landing gear arrangement. 25.477 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.477 Landing gear arrangement. Sections 25.479 through 25.485 apply to airplanes with conventional arrangements of main and nose gears,...

  20. 14 CFR 25.477 - Landing gear arrangement.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Landing gear arrangement. 25.477 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.477 Landing gear arrangement. Sections 25.479 through 25.485 apply to airplanes with conventional arrangements of main and nose gears,...

  1. 14 CFR 25.477 - Landing gear arrangement.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing gear arrangement. 25.477 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.477 Landing gear arrangement. Sections 25.479 through 25.485 apply to airplanes with conventional arrangements of main and nose gears,...

  2. 14 CFR 121.289 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Landing gear: Aural warning device. 121.289... gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing gear aural warning...

  3. 14 CFR 25.477 - Landing gear arrangement.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Landing gear arrangement. 25.477 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.477 Landing gear arrangement. Sections 25.479 through 25.485 apply to airplanes with conventional arrangements of main and nose gears,...

  4. 14 CFR 25.477 - Landing gear arrangement.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Landing gear arrangement. 25.477 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.477 Landing gear arrangement. Sections 25.479 through 25.485 apply to airplanes with conventional arrangements of main and nose gears,...

  5. 14 CFR 121.289 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Landing gear: Aural warning device. 121.289... gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing gear aural warning...

  6. 14 CFR 121.289 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Landing gear: Aural warning device. 121.289... gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing gear aural warning...

  7. 14 CFR 121.289 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Landing gear: Aural warning device. 121.289... gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing gear aural warning...

  8. X-38 Landing Gear qualification testing

    NASA Astrophysics Data System (ADS)

    Urgoiti, Eduardo

    2003-09-01

    The Landing Gear System for the X-38 demonstration vehicle has been developed considering future application to the CRV vehicle. It consists of three legs in a typical aeroplane configuration with two main and one nose legs. They are retracted during ascent, in orbit and re-entry phases and are released near the ground by pyrotechnic-nuts and deployed by preloaded springs and gravity. This gear has been designed to allow landing in unprepared plain fields limiting the accelerations on the spacecraft at touch down, through expendable damping cartridges and skids. During 2002 the test campaign of the X-38 Landing Gear has been completed at Sener. Three different types of tests have been performed: Functional deployment tests, Static load tests and vibration tests. This paper discusses the objectives of the tests and how they are achieved with a description of the mechanisms involved and their predicted performances. The different types of tests and results are described together with the major events and lessons learned during their performance.

  9. Performance evaluation on vibration control of MR landing gear

    NASA Astrophysics Data System (ADS)

    Lee, D. Y.; Nam, Y. J.; Yamane, R.; Park, M. K.

    2009-02-01

    This paper is concerned with the applicability of the developed MR damper to the landing gear system for the attenuating undesired shock and vibration in the landing and taxing phases. First of all, the experimental model of the MR damper is derived based on the results of performance evaluations. Next, a simplified skyhook controller, which is one of the most straightforward, but effective approaches for improving ride comport in vehicles with active suspensions, is formulated. Then, the vibration control performances of the landing gear system using the MR damper are theoretically evaluated in the landing phase of the aircraft. A series of simulation analyses show that the proposed MR damper with the skyhook controller is effective for suppressing undesired vibration of the aircraft body. Finally, the effectiveness of the simulation results are additionally verified via HILS (Hardware-in-the-loop-simulation) method.

  10. Aeroacoustic Analysis of a Simplified Landing Gear

    NASA Technical Reports Server (NTRS)

    Lockard, David P.; Khorrami, Mehdi, R.; Li, Fei

    2004-01-01

    A hybrid approach is used to investigate the noise generated by a simplified landing gear without small scale parts such as hydraulic lines and fasteners. The Ffowcs Williams and Hawkings equation is used to predict the noise at far-field observer locations from flow data provided by an unsteady computational fluid dynamics calculation. A simulation with 13 million grid points has been completed, and comparisons are made between calculations with different turbulence models. Results indicate that the turbulence model has a profound effect on the levels and character of the unsteadiness. Flow data on solid surfaces and a set of permeable surfaces surrounding the gear have been collected. Noise predictions using the porous surfaces appear to be contaminated by errors caused by large wake fluctuations passing through the surfaces. However, comparisons between predictions using the solid surfaces with the near-field CFD solution are in good agreement giving confidence in the far-field results.

  11. The NASA landing gear test airplane

    NASA Technical Reports Server (NTRS)

    Carter, John F.; Nagy, Christopher J.

    1995-01-01

    A tire and landing gear test facility has been developed and incorporated into a Convair 990 aircraft. The system can simulate tire vertical load profiles to 250,000 lb, sideslip angles to 15 degrees, and wheel braking on actual runways. Onboard computers control the preprogrammed test profiles through a feedback loop and also record three axis loads, tire slip angle, and tire condition. The aircraft to date has provided tire force and wear data for the Shuttle Orbiter tire on three different runways and at east and west coast landing sites. This report discusses the role of this facility in complementing existing ground tire and landing gear test facilities, and how this facility can simultaneously simulate the vertical load, tire slip, velocity, and surface for an entire aircraft landing. A description is given of the aircraft as well as the test system. An example of a typical test sequence is presented. Data collection and reduction from this facility are discussed, as well as accuracies of calculated parameters. Validation of the facility through ground and flight tests is presented. Tests to date have shown that this facility can operate at remote sites and gather complete data sets of load, slip, and velocity on actual runway surfaces. The ground and flight tests have led to a successful validation of this test facility.

  12. Landing Gear Door Liners for Airframe Noise Reduction

    NASA Technical Reports Server (NTRS)

    Jones, Michael G. (Inventor); Howerton, Brian M. (Inventor); Van De Ven, Thomas (Inventor)

    2014-01-01

    A landing gear door for retractable landing gear of aircraft includes an acoustic liner. The acoustic liner includes one or more internal cavities or chambers having one or more openings that inhibit the generation of sound at the surface and/or absorb sound generated during operation of the aircraft. The landing gear door may include a plurality of internal chambers having different geometries to thereby absorb broadband noise.

  13. 14 CFR 125.187 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Landing gear: Aural warning device. 125.187... Requirements § 125.187 Landing gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing...

  14. 14 CFR 125.187 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Landing gear: Aural warning device. 125.187... Requirements § 125.187 Landing gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing...

  15. 14 CFR 125.187 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Landing gear: Aural warning device. 125.187... Requirements § 125.187 Landing gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing...

  16. 14 CFR 125.187 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Landing gear: Aural warning device. 125.187... Requirements § 125.187 Landing gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing...

  17. 14 CFR 125.187 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Landing gear: Aural warning device. 125.187... Requirements § 125.187 Landing gear: Aural warning device. (a) Except for airplanes that comply with the requirements of § 25.729 of this chapter on or after January 6, 1992, each airplane must have a landing...

  18. Composite skid landing gear design investigation

    NASA Astrophysics Data System (ADS)

    Shrotri, Kshitij

    A Composite Skid Landing Gear Design investigation has been conducted. Limit Drop Test as per Federal Aviation Regulations (FAR) Part 27.725 and Crash test as per MIL STD 1290A (AV) were simulated using ABAQUS to evaluate performance of multiple composite fiber-matrix systems. Load factor developed during multiple landing scenarios and energy dissipated during crash were computed. Strength and stiffness based constraints were imposed. Tsai-Wu and LaRC04 physics based failure criteria were used for limit loads. Hashin's damage initiation criteria with Davila-Camanho's energy based damage evolution damage evolution law were used for crash. Initial results indicate that all single-composite skid landing gear may no be feasible due to strength concerns in the cross member bends. Hybridization of multiple composites with elasto-plastic aluminum 7075 showed proof of strength under limit loads. Laminate tailoring for load factor optimization under limit loads was done by parameterization of a single variable fiber orientation angle for multiple laminate families. Tsai-Wu failure criterion was used to impose strength contraints. A quasi-isotropic N = 4 (pi/4) 48 ply IM7/8552 laminate was shown to be the optimal solution with a load failure will be initiated as matrix cracking under compression and fiber kinking under in-plane shear and longitudinal compression. All failures under limit loads being reported in the metal-composite hybrid joint region, the joint was simulated by adhesive bonding and filament winding, separately. Simply adhesive bonding the metal and composite regions does not meet strength requirements. A filament wound metal-composite joint shows proof of strength. Filament wound bolted metal-composite joint shows proof of strength. Filament wound composite bolted to metal cross member radii is the final joining methodology. Finally, crash analysis was conducted as per requirements from MIL STD 1290A (AV). Crash at 42 ft/sec with 1 design gross weight (DGW

  19. Prediction of Landing Gear Noise Reduction and Comparison to Measurements

    NASA Technical Reports Server (NTRS)

    Lopes, Leonard V.

    2010-01-01

    Noise continues to be an ongoing problem for existing aircraft in flight and is projected to be a concern for next generation designs. During landing, when the engines are operating at reduced power, the noise from the airframe, of which landing gear noise is an important part, is equal to the engine noise. There are several methods of predicting landing gear noise, but none have been applied to predict the change in noise due to a change in landing gear design. The current effort uses the Landing Gear Model and Acoustic Prediction (LGMAP) code, developed at The Pennsylvania State University to predict the noise from landing gear. These predictions include the influence of noise reduction concepts on the landing gear noise. LGMAP is compared to wind tunnel experiments of a 6.3%-scale Boeing 777 main gear performed in the Quiet Flow Facility (QFF) at NASA Langley. The geometries tested in the QFF include the landing gear with and without a toboggan fairing and the door. It is shown that LGMAP is able to predict the noise directives and spectra from the model-scale test for the baseline configuration as accurately as current gear prediction methods. However, LGMAP is also able to predict the difference in noise caused by the toboggan fairing and by removing the landing gear door. LGMAP is also compared to far-field ground-based flush-mounted microphone measurements from the 2005 Quiet Technology Demonstrator 2 (QTD 2) flight test. These comparisons include a Boeing 777-300ER with and without a toboggan fairing that demonstrate that LGMAP can be applied to full-scale flyover measurements. LGMAP predictions of the noise generated by the nose gear on the main gear measurements are also shown.

  20. STS-86 Landing (Main Gear Touchdown)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Space Shuttle orbiter Atlantis touches down on Runway 15 of the KSC Shuttle Landing Facility (SLF) to complete the nearly 11- day STS-86 mission. Main gear touchdown was at 5:55:09 p.m. EDT on Oct. 6, 1997. The unofficial mission-elapsed time at main gear touchdown was 10 days, 19 hours, 20 minutes and 50 seconds. The first two landing opportunities on Sunday were waved off because of weather concerns. The 87th Space Shuttle mission was the 40th landing of the Shuttle at KSC. On Sunday evening, the Space Shuttle program reached a milestone: The total flight time of the Shuttle passed the two-year mark. STS-86 was the seventh of nine planned dockings of the Space Shuttle with the Russian Space Station Mir. STS-86 Mission Specialist David A. Wolf replaced NASA astronaut and Mir 24 crew member C. Michael Foale, who has been on the Mir since mid-May. Foale returned to Earth on Atlantis with the remainder of the STS-86 crew. The other crew members are Commander James D. Wetherbee, Pilot Michael J. Bloomfield, and Mission Specialists Wendy B. Lawrence, Scott E. Parazynski, Vladimir Georgievich Titov of the Russian Space Agency, and Jean-Loup J.M. Chretien of the French Space Agency, CNES. Wolf is scheduled to remain on the Mir until the STS-89 Shuttle mission in January. Besides the docking and crew exchange, STS-86 included the transfer of more than three-and-a- half tons of science/logistical equipment and supplies between the two orbiting spacecraft. Parazynski and Titov also conducted a spacewalk while Atlantis and the Mir were docked.

  1. Investigations of Shuttle Main Landing Gear Door Environmental Seals

    NASA Technical Reports Server (NTRS)

    Finkbeiner, Joshua; Dunlap, Pat; Steinetz, Bruce; DeMango, Jeff; Newswander, Daniel

    2005-01-01

    The environmental seals for the main landing gear doors of the Shuttle Orbiters were raised by the Columbia Accident Investigation Board as a potential safety concern. Inspections of seals installed on the Shuttle Discovery revealed that they were permanently deformed and no longer met certified seal compression requirements. Replacement of the seals led to the inability to fully close the main landing gear doors. Johnson Space Center requested that Glenn Research Center conduct tests on the main landing gear door environmental seals to assist in installing the seals in a manner to allow the main landing gear doors to fully close. Further testing was conducted to fill out the seal performance database. Results from the testing indicated that the method of bonding the seals was important in reducing seal loads on the main landing gear doors. Also, the replacement seals installed in Shuttle Discovery were found to have leakage performance sufficient to meet the certification requirements.

  2. The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears II : Nonretractable and Partly Retractable Landing Gears

    NASA Technical Reports Server (NTRS)

    Biermann, David; Herrnstein, William H , Jr

    1936-01-01

    This is the second report giving the results obtained in the NACA 20-foot wind tunnel on the drag due to landing gears. The present report gives the results of tests of nonretractable and partly retractable landing gears intended for heavier low-wing monoplanes of the transport and bomber type.

  3. Air cushion landing gear applications study

    NASA Technical Reports Server (NTRS)

    Earl, T. D.

    1979-01-01

    A series of air cushion landing gear (ACLG) applications was studied and potential benefits analyzed in order to identify the most attractive of these. The selected applications are new integrated designs (not retrofits) and employ a modified design approach with improved characteristics and performance. To aid the study, a survey of potential users was made. Applications were evaluated in the light of comments received. A technology scenario is developed, with discussion of problem areas, current technology level and future needs. Feasible development timetables are suggested. It is concluded that near-term development of small-size ACLG trunks, exploration of flight effects and braking are key items. The most attractive applications are amphibious with very large cargo aircraft and small general aviation having the greatest potential.

  4. Simulation of X-38 Landing Scenarios With Landing Gear Failures

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Lyle, Karen H.; Pritchard, Jocelyn I.; Stockwell, Alan E.

    2000-01-01

    Abnormal landing scenarios of the X-38 prototype Crew Rescue Vehicle (CRV) were modeled for three different cases involving non-deployment of landing gear with an explicit dynamic nonlinear finite element code, MSC/DYTRAN. The goal of this research was to develop models to predict the probability of crew injuries. The initial velocity conditions for the X-38 with chute deployed were 10 ft/s vertical and 57 ft/s longitudinal velocity. An MSC/NASTRAN structural model was supplied by JSC and was converted to a dynamic MSC/DYTRAN model. The MSC/NASTRAN model did not include seats or floor structure; thus, the acceleration of a lumped-mass attached to the bulkhead near each assumed occupant location was used to determine injury risk for each occupant. The worst case for injury was nondeployment of all gears. The mildest case was nondeployment of one main gear. Although a probability for minor injury was predicted for all cases, it is expected that the addition of energy-absorbing floor structure and seats would greatly diminish the probability of injury.

  5. Application of tire dynamics to aircraft landing gear design analysis

    NASA Technical Reports Server (NTRS)

    Black, R. J.

    1983-01-01

    The tire plays a key part in many analyses used for design of aircraft landing gear. Examples include structural design of wheels, landing gear shimmy, brake whirl, chatter and squeal, complex combination of chatter and shimmy on main landing gear (MLG) systems, anti-skid performance, gear walk, and rough terrain loads and performance. Tire parameters needed in the various analyses are discussed. Two tire models are discussed for shimmy analysis, the modified Moreland approach and the von Schlippe-Dietrich approach. It is shown that the Moreland model can be derived from the Von Schlippe-Dietrich model by certain approximations. The remaining analysis areas are discussed in general terms and the tire parameters needed for each are identified. Accurate tire data allows more accurate design analysis and the correct prediction of dynamic performance of aircraft landing gear.

  6. Increased Fidelity in Prediction Methods For Landing Gear Noise

    NASA Technical Reports Server (NTRS)

    Lopes, Leonard V.; Brentner, Kenneth S.; Morris, Philip J.; Lockhard, David P.

    2006-01-01

    An aeroacoustic prediction scheme has been developed for landing gear noise. The method is designed to handle the complex landing gear geometry of current and future aircraft. The gear is represented by a collection of subassemblies and simple components that are modeled using acoustic elements. These acoustic elements are generic, but generate noise representative of the physical components on a landing gear. The method sums the noise radiation from each component of the undercarriage in isolation accounting for interference with adjacent components through an estimate of the local upstream and downstream flows and turbulence intensities. The acoustic calculations are made in the code LGMAP, which computes the sound pressure levels at various observer locations. The method can calculate the noise from the undercarriage in isolation or installed on an aircraft for both main and nose landing gear. Comparisons with wind tunnel and flight data are used to initially calibrate the method, then it may be used to predict the noise of any landing gear. In this paper, noise predictions are compared with wind tunnel data for model landing gears of various scales and levels of fidelity, as well as with flight data on fullscale undercarriages. The present agreement between the calculations and measurements suggests the method has promise for future application in the prediction of airframe noise.

  7. 14 CFR 121.289 - Landing gear: Aural warning device.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... climb configuration position in the Airplane Flight Manual and the landing gear is not fully extended and locked. (2) For airplanes without an established approach climb wing-flap position, whenever...

  8. 14 CFR 25.483 - One-gear landing conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... conditions. For the one-gear landing conditions, the airplane is assumed to be in the level attitude and to... this attitude— (a) The ground reactions must be the same as those obtained on that side under §...

  9. Demonstrations of bio-inspired perching landing gear for UAVs

    NASA Astrophysics Data System (ADS)

    Tieu, Mindy; Michael, Duncan M.; Pflueger, Jeffery B.; Sethi, Manik S.; Shimazu, Kelli N.; Anthony, Tatiana M.; Lee, Christopher L.

    2016-04-01

    Results are presented which demonstrate the feasibility and performance of two concepts of biologically-inspired landing-gear systems that enable bird-sized, unmanned aerial vehicles (UAV's) to land, perch, and take-off from branchlike structures and/or ledges. The first concept follows the anatomy of birds that can grasp ahold of a branch and perch as tendons in their legs are tensioned. This design involves a gravity-activated, cable-driven, underactuated, graspingfoot mechanism. As the UAV lands, its weight collapses a four-bar linkage pulling a cable which curls two opposing, multi-segmented feet to grasp the landing target. Each foot is a single, compliant mechanism fabricated by simultaneouly 3D-printing a flexible thermo-plastic and a stiffer ABS plastic. The design is optimized to grasp structures over a range of shapes and sizes. Quasi-static and flight tests of this landing gear affixed to RC rotorcraft (24 cm to 550 cm in diameter) demonstrate that the aircraft can land, perch, and take-off from a tree branch, rectangular wood board, PVC pipe, metal hand rail, chair armrest, and in addition, a stone wall ledge. Stability tests show that perching is maintained under base and wind disturbances. The second design concept, inspired by roosting bats, is a two-material, 3D-printed hooking mechanism that enables the UAV to stably suspend itself from a wire or small-diameter branch. The design balances structural stiffness for support and flexibility for the perching process. A flight-test demonstrates the attaching and dis-engaging of a small, RC quadcopter from a suspended line.

  10. Potential for Landing Gear Noise Reduction on Advanced Aircraft Configurations

    NASA Technical Reports Server (NTRS)

    Thomas, Russell H.; Nickol, Craig L.; Burley, Casey L.; Guo, Yueping

    2016-01-01

    The potential of significantly reducing aircraft landing gear noise is explored for aircraft configurations with engines installed above the wings or the fuselage. An innovative concept is studied that does not alter the main gear assembly itself but does shorten the main strut and integrates the gear in pods whose interior surfaces are treated with acoustic liner. The concept is meant to achieve maximum noise reduction so that main landing gears can be eliminated as a major source of airframe noise. By applying this concept to an aircraft configuration with 2025 entry-into-service technology levels, it is shown that compared to noise levels of current technology, the main gear noise can be reduced by 10 EPNL dB, bringing the main gear noise close to a floor established by other components such as the nose gear. The assessment of the noise reduction potential accounts for design features for the advanced aircraft configuration and includes the effects of local flow velocity in and around the pods, gear noise reflection from the airframe, and reflection and attenuation from acoustic liner treatment on pod surfaces and doors. A technical roadmap for maturing this concept is discussed, and the possible drag increase at cruise due to the addition of the pods is identified as a challenge, which needs to be quantified and minimized possibly with the combination of detailed design and application of drag reduction technologies.

  11. An Impulse-Momentum Method for Calculating Landing-Gear Contact Conditions in Eccentric Landings

    NASA Technical Reports Server (NTRS)

    Yntema, Robert T; Milwitzky, Benjamin

    1952-01-01

    An impulse-momentum method for determining impact conditions for landing gears in eccentric landings is presented. The analysis is primarily concerned with the determination of contact velocities for impacts subsequent to initial touchdown in eccentric landings and with the determination of the effective mass acting on each landing gear. These parameters determine the energy-absorption requirements for the landing gear and, in conjunction with the particular characteristics of the landing gear, govern the magnitude of the ground loads. Changes in airplane angular and linear velocities and the magnitude of landing-gear vertical, drag, and side impulses resulting from a landing impact are determined by means of impulse-momentum relationships without the necessity for considering detailed force-time variations. The effective mass acting on each gear is also determined from the calculated landing-gear impulses. General equations applicable to any type of eccentric landing are written and solutions are obtained for the particular cases of an impact on one gear, a simultaneous impact on any two gears, and a symmetrical impact. In addition a solution is presented for a simplified two-degree-of-freedom system which allows rapid qualitative evaluation of the effects of certain principal parameters. The general analysis permits evaluation of the importance of such initial conditions at ground contact as vertical, horizontal, and side drift velocities, wing lift, roll and pitch angles, and rolling and pitching velocities, as well as the effects of such factors as landing gear location, airplane inertia, landing-gear length, energy-absorption efficiency, and wheel angular inertia on the severity of landing impacts. -A brief supplementary study which permits a limited evaluation of variable aerodynamic effects neglected in the analysis is presented in the appendix. Application of the analysis indicates that landing-gear impacts in eccentric landings can be appreciably more

  12. A Landing Gear Noise Reduction Study Based on Computational Simulations

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Lockard, David P.

    2006-01-01

    Landing gear is one of the more prominent airframe noise sources. Techniques that diminish gear noise and suppress its radiation to the ground are highly desirable. Using a hybrid computational approach, this paper investigates the noise reduction potential of devices added to a simplified main landing gear model without small scale geometric details. The Ffowcs Williams and Hawkings equation is used to predict the noise at far-field observer locations from surface pressure data provided by unsteady CFD calculations. Because of the simplified nature of the model, most of the flow unsteadiness is restricted to low frequencies. The wheels, gear boxes, and oleo appear to be the primary sources of unsteadiness at these frequencies. The addition of fairings around the gear boxes and wheels, and the attachment of a splitter plate on the downstream side of the oleo significantly reduces the noise over a wide range of frequencies, but a dramatic increase in noise is observed at one frequency. The increased flow velocities, a consequence of the more streamlined bodies, appear to generate extra unsteadiness around other parts giving rise to the additional noise. Nonetheless, the calculations demonstrate the capability of the devices to improve overall landing gear noise.

  13. Initial noise predictions for rudimentary landing gear

    NASA Astrophysics Data System (ADS)

    Spalart, Philippe R.; Shur, Mikhail L.; Strelets, Mikhail Kh.; Travin, Andrey K.

    2011-08-01

    A four-wheel "rudimentary" landing gear (RLG) truck was designed for public-domain research, with a level of complexity which is manageable in current numerical simulations, and a weak Reynolds-number sensitivity. Experimental measurements of wall-pressure fluctuations are allowing a meaningful test of unsteady simulations with emphasis on noise generation. We present three Detached-Eddy Simulations (DES) using up to 18 million points in the high-order NTS code. The first is incompressible with the model placed in the wind tunnel, as requested for the 2010 workshop on Benchmark problems for Airframe Noise Computations (BANC-I), intended for force and surface-pressure studies. The second and third are at Mach 0.115 and Mach 0.23, with only one wall, a "ceiling" analogous to a wing (but infinite and inviscid), and are used to exercise far-field noise prediction by coupling the Detached-Eddy Simulations and a Ffowcs-Williams/Hawkings calculation. The results include wall-pressure, and far-field-noise intensities and spectra. The wall pressure signals in the three simulations are very similar and, in a comparison published separately, agree well with experiment and other simulations. In the absence of experimental noise data, the attention is focused on internal quality checks, by varying the permeable Ffowcs-Williams/Hawkings calculation surface and then by using only the solid surface. An unexpected finding at these Mach numbers is an apparent strong role for quadrupoles, revealed by a typical deficit of 3 dB in the solid-surface results, relative to the permeable-surface results. The solid-surface approach has variants, related to the presence of the ceiling (a plane of symmetry), which can increase this error further; there is little consensus on the exact configuration of the solid surfaces in the Ffowcs-Williams/Hawkings calculation procedure. Tentative theoretical arguments suggest that a balance somewhat in favor of quadrupoles over dipoles is plausible at Mach

  14. Unsteady Simulation of a Landing-Gear Flow Field

    NASA Technical Reports Server (NTRS)

    Li, Fei; Khorrami, Mehdi R.; Malik, Mujeeb R.

    2002-01-01

    This paper presents results of an unsteady Reynolds-averaged Navier-Stokes simulation of a landing-gear flow field. The geometry of the four-wheel landing gear assembly consists of several of the fine details including the oleo-strut, two diagonal struts, a door, yokes/pin and a flat-plate simulating the wing surface. The computational results, obtained by using 13.3 million grid points, are presented with an emphasis on the characteristics of the unsteadiness ensuing from different parts of the landing-gear assembly, including vortex shedding patterns and frequencies of dominant oscillations. The results show that the presence of the diagonal struts and the door significantly influence the flow field. Owing to the induced asymmetry, vortices are shed only from one of the rear wheels and not the other. Present computations also capture streamwise vortices originating from the upstream corners of the door.

  15. Aeroacoustic Evaluation of Flap and Landing Gear Noise Reduction Concepts

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Humphreys, William M., Jr.; Lockard, David P.; Ravetta, Patricio A.

    2014-01-01

    Aeroacoustic measurements for a semi-span, 18% scale, high-fidelity Gulfstream aircraft model are presented. The model was used as a test bed to conduct detailed studies of flap and main landing gear noise sources and to determine the effectiveness of numerous noise mitigation concepts. Using a traversing microphone array in the flyover direction, an extensive set of acoustic data was obtained in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel with the facility in the acoustically treated open-wall (jet) mode. Most of the information was acquired with the model in a landing configuration with the flap deflected 39 deg and the main landing gear alternately installed and removed. Data were obtained at Mach numbers of 0.16, 0.20, and 0.24 over directivity angles between 56 deg and 116 deg, with 90 deg representing the overhead direction. Measured acoustic spectra showed that several of the tested flap noise reduction concepts decrease the sound pressure levels by 2 - 4 dB over the entire frequency range at all directivity angles. Slightly lower levels of noise reduction from the main landing gear were obtained through the simultaneous application of various gear devices. Measured aerodynamic forces indicated that the tested gear/flap noise abatement technologies have a negligible impact on the aerodynamic performance of the aircraft model.

  16. 14 CFR 27.549 - Fuselage, landing gear, and rotor pylon structures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 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...

  17. 14 CFR 27.549 - Fuselage, landing gear, and rotor pylon structures.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 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...

  18. Innovative Anti Crash Absorber for a Crashworthy Landing Gear

    NASA Astrophysics Data System (ADS)

    Guida, Michele; Marulo, Francesco; Montesarchio, Bruno; Bruno, Massimiliano

    2014-06-01

    This paper defines an innovative concept to anti-crash absorber in composite material to be integrated on the landing gear as an energy-absorbing device in crash conditions to absorb the impact energy. A composite cylinder tube in carbon fiber material is installed coaxially to the shock absorber cylinder and, in an emergency landing gear condition, collapses in order to enhance the energy absorption performance of the landing system. This mechanism has been developed as an alternative solution to a high-pressure chamber installed on the Agusta A129 CBT helicopter, which can be considered dangerous when the helicopter operates in hard and/or crash landing. The characteristics of the anti-crash device are presented and the structural layout of a crashworthy landing gear adopting the developed additional energy absorbing stage is outlined. Experimental and numerical results relevant to the material characterization and the force peaks evaluation of the system development are reported. The anti-crash prototype was designed, analysed, optimized, made and finally the potential performances of a landing gear with the additional anti-crash absorber system are tested by drop test and then correlated with a similar test without the anti-crash system, showing that appreciable energy absorbing capabilities and efficiencies can be obtained in crash conditions.

  19. Study on passive momentum exchange landing gear using two-dimensional analysis

    NASA Astrophysics Data System (ADS)

    Watanabe, Tsubasa; Hara, Susumu; Otsuki, Masatsugu

    2014-12-01

    This paper discusses a landing response control system based on the momentum exchange principle for planetary exploration spacecraft. In the past, landing gear systems with cantilever designs that incorporate honeycomb materials to dissipate shock energy through plastic deformation have been used, but once tested before launch, the system cannot be used in a real mission. The sky crane system used for the Mars Science Laboratory by NASA can achieve a safe and precise landing, but it is highly complex. This paper introduces a momentum exchange impact damper (MEID) that absorbs the controlled object's momentum with extra masses called damper masses. The MEID is reusable, which makes it easy to ensure the landing gear's reliability. In this system, only passive elements such as springs are needed. A single-axis (SA) model has already been used to verify the effectiveness of MEIDs through simulations and experiments measuring the rebound height of the spacecraft. However, the SA model cannot address the rotational motion and tipping of the spacecraft. This paper presents a two-landing-gear-system (TLGS) model in which multiple MEIDs are equipped for two-dimensional analysis. Unlike in the authors' previous studies, in this study each MEID is launched when the corresponding landing gear lands and the MEIDs do not contain active actuators. This mechanism can be used to realize advanced control specifications, and it is simply compared with previous mechanisms including actuators, in which all of the MEIDs are launched simultaneously. If each MEID works when the corresponding gear lands, the rebound height of each gear can be minimized, and tipping can be prevented, as demonstrated by the results of our simulations.

  20. STS-74 landing (Main Gear Touchdown closeup)

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The highly successful Mission STS-74 comes to a smooth conclusion as the orbiter Atlantis returns to Kennedy Space Center. Atlantis touched down on Runway 33 of the Shuttle Landing Facility at 12:01:27 p.m. EST, November 20. The final Space Shuttle flight of 1995 marked the second docking of the U.S. Space Shuttle to the Russian Space Station Mir. To simplify the remaining five Shuttle-Mir docking currently scheduled, the five astronauts on Atlantis attached a Russian-built Docking Module to Mir during the eight-day mission. Two solar arrays were stowed on the module, which will serve as a permanent extension to the Kristall docking port on the station. Atlantis' crew and the three cosmonauts on Mir also transferred materials to and from the station. Leading the STS-74 crew is Commander Kenneth D. Cameron; James D. Halsell Jr. is the pilot; the three mission specialists are Jerry L. Ross, William S. 'Bill' McArthur Jr. and Chris A. Hadfield, who represents the Canadian Space Agency. This was the 27th end-of-mission landing at KSC in Shuttle program history. The Shuttle-Mir dockings are one aspect of Phase 1 activities leading the way toward the international space station; the United States, Russian, Canada, Japan and a group of European nations have joined together to build the orbiting outpost in space later this decade.

  1. Numerical Simulations for Landing Gear Noise Generation and Radiation

    NASA Technical Reports Server (NTRS)

    Morris, Philip J.; Long, Lyle N.

    2002-01-01

    Aerodynamic noise from a landing gear in a uniform flow is computed using the Ffowcs Williams -Hawkings (FW-H) equation. The time accurate flow data on the surface is obtained using a finite volume flow solver on an unstructured and. The Ffowcs Williams-Hawkings equation is solved using surface integrals over the landing gear surface and over a permeable surface away from the landing gear. Two geometric configurations are tested in order to assess the impact of two lateral struts on the sound level and directivity in the far-field. Predictions from the Ffowcs Williams-Hawkings code are compared with direct calculations by the flow solver at several observer locations inside the computational domain. The permeable Ffowcs Williams-Hawkings surface predictions match those of the flow solver in the near-field. Far-field noise calculations coincide for both integration surfaces. The increase in drag observed between the two landing gear configurations is reflected in the sound pressure level and directivity mainly in the streamwise direction.

  2. 14 CFR 27.549 - Fuselage, landing gear, and rotor pylon structures.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuselage, landing gear, and rotor pylon structures. 27.549 Section 27.549 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Requirements § 27.549 Fuselage, landing gear, and rotor pylon structures. (a) Each fuselage, landing gear,...

  3. Metallurgical analysis of fractured F-27 aircraft landing gear

    SciTech Connect

    Witherell, C.E.

    1987-12-15

    The Materials Division of LLNL's Chemistry and Materials Science Department was asked to conduct a study of a fractured component of the main (starboard) landing gear on the F-27 aircraft (N768RL). The purpose of the study was to determine from metallurgical evidence the probable failure mode, its cause, and contribution to the recent landing incident at Livermore. 21 refs., 15 figs., 1 tab.

  4. Retraction Assembly for Space Shuttle Extended Nose Landing Gear

    NASA Technical Reports Server (NTRS)

    Files, Bradley S.; Nicholson, Leonard S. (Technical Monitor)

    2000-01-01

    As part of a project to encourage the use of shape memory alloy actuators for space actuators, this mechanism uses a nitinol ribbon to provide the necessary motion to help retract the proposed extended nose landing gear (ENLG) for the space shuttle. Initial proof-of-concept design of the ENLG did not include the ability to retract the gear automatically. One proposed actuator for this purpose was designed at Johnson Space Center and uses resistive heating to rotate the ribbon around a cylinder. This rotation then allows the assembly to pull down a wedge that is used to hold the landing gear strut in place, thus returning the landing gear to its previous height before extension. The presentation will follow the design of this assembly from working with the nitinol ribbon to providing mechanical connections and allowing minimal friction for motion of three wraps around a cylinder. Also to be presented is preliminary work on design of a shape memory alloy gripper, a design project to demonstrate uses of NiTi.

  5. Aerodynamics of a Gulfstream G550 Nose Landing Gear Model

    NASA Technical Reports Server (NTRS)

    Neuhart, Dan H.; Khorrami, Mehdi R.; Choudhari, Meelan M.

    2009-01-01

    In this paper we discuss detailed steady and unsteady aerodynamic measurements of a Gulfstream G550 nose landing gear model. The quarter-scale, high-fidelity model includes part of the lower fuselage and the gear cavity. The full model configuration allowed for removal of various gear components (e.g. light cluster, steering mechanism, hydraulic lines, etc.) in order to document their effects on the local flow field. The measurements were conducted at a Reynolds number of 7.3 x 10(exp 4) based on the shock strut (piston) diameter and a freestream Mach number of 0.166. Additional data were also collected at lower Mach numbers of 0.12 and 0.145 and correspondingly lower Reynolds numbers. The boundary layer on the piston was tripped to enable turbulent flow separation, so as to better mimic the conditions encountered during flight. Steady surface pressures were gathered from an extensive number of static ports on the wheels, door, fuselage, and within the gear cavity. To better understand the resultant flow interactions between gear components, surface pressure fluctuations were collected via sixteen dynamic pressure sensors strategically placed on various subcomponents of the gear. Fifteen of the transducers were flush mounted on the gear surface at fixed locations, while the remaining one was a mobile transducer that could be placed at numerous varying locations. The measured surface pressure spectra are mainly broadband in nature, lacking any local peaks associated with coherent vortex shedding. This finding is in agreement with off-surface flow measurements using PIV that revealed the flow field to be a collection of separated shear layers without any dominant vortex shedding processes.

  6. Flight investigation of piloting techniques and crosswind limitations using a research type crosswind landing gear

    NASA Technical Reports Server (NTRS)

    Fisher, B. D.; Deal, P. L.; Champine, R. A.; Patton, J. M., Jr.

    1979-01-01

    A research-type crosswind landing gear was tested in a flight program which used a light STOL transport in strong crosswind conditions. The research-type crosswind landing gear used enabled the airplane to land to crosswinds up to a magnitude of 25 to 30 knots. Three modes of landing-gear operation were investigated: preset, automatic, and castor (passive self-alignment). Actual test data and histograms are given for the 195 'visual flight rules' crosswind landings made.

  7. Characteristics of a Lunar Landing Configuration Having Various Multiple-Leg Landing-Gears

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Characteristics of a Lunar Landing Configuration Having Various Multiple-Leg Landing-Gear Arrangements. An experimental investigation has been made of some lunar-landing characteristics of a 1/6-scale dynamic model of a landing module having multiple-leg landing-gear systems. Symmetric four-point and five-point systems and an asymmetric four-point system were investigated. The landing-gear legs were inverted tripod arrangements having a telescoping main strut which incorporated a yielding-metal strap for energy dissipation, hinged V-struts, and circular pads. The landing tests were made by launching a free model onto an impenetrable hard surface (concrete) and onto a powdered-pumice overlay of various depths. Landing motion and acceleration data were obtained for a range of touchdown speeds, touchdown speeds, touch attitudes, and landing-surface conditions. Symmetric four-point and five-point systems and an Maximum normal acceleration experienced at the module center of gravity during landings on hard surface or pumice was 2g (full-scale lunar value in terms of earth's gravity) over a wide range of touchdown conditions. Maximum angular acceleration experienced was 12-1/2 radians/sec(exp 2) and maximum longitudinal acceleration was 1-3/4 g. The module was very stable with all gear configurations during landings on hard surface (coefficient of friction, microns=0.4) at all conditions tested. Some overturn instability occurred during landings on powdered pumice (microns=0.7 to 1.0) depending upon flight path, pitch and yaw attitude, depth of pumice, surface topography, and landing-gear configuration. The effect of stability of roll attitude for the limited amount of roll-attitude landing data obtained was insignificant. Compared with the four-point system, the five-point system with equal maximum gear radius increased landing stability slightly and improved the static stability for subsequent lunar launch. A considerable increase in landing stability in the direction

  8. Effect of interaction on landing-gear behavior and dynamic loads in a flexible airplane structure

    NASA Technical Reports Server (NTRS)

    Cook, Francis E; Milwitzky, Benjamin

    1956-01-01

    The effects of interaction between a landing gear and a flexible airplane structure on the behavior of the landing gear and the loads in the structure have been studied by treating the equations of motion of the airplane and the landing gear as a coupled system. The landing gear is considered to have nonlinear characteristics typical of conventional gears, namely, velocity-squared damping, polytropic air-compression springing, and exponential tire force-deflection characteristics. For the case where only two modes of the structure are considered, an equivalent three-mass system is derived for representing the airplane and landing-gear combination, which may be used to simulate the effects of structural flexibility in jig drop tests of landing gears. As examples to illustrate the effects of interaction, numerical calculations, based on the structural properties of two large airplanes having considerably different mass and flexibility characteristics, are presented.

  9. Detail View looking at the protected structure and landing gear ...

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

    Detail View looking at the protected structure and landing gear housing in the void created by the removal of the Forward Reaction Control System Module from the forward section of the Orbiter Discovery. This view was taken from the 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

  10. STS-79 Atlantis Landing (main gear touchdown)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The STS-79 mission comes to a successful conclusion as the orbiter Atlantis touches down on Runway 15 of KSC's Shuttle Landing Facility at 8:13:15 a.m. EDT, September 26. On board is U.S. astronaut Shannon W. Lucid, who has been living and working on the Russian Space Station Mir for about six months. Lucid has spent 188 days in space from launch aboard Atlantis in March to her return today, establishing a U.S. record for long-duration spaceflight as well as representing the longest spaceflight for a woman. Succeeding Lucid on Mir is U.S. astronaut John E. Blaha, who embarked to Mir with the STS-79 crew. The commander of Mission STS-79 is William F. Readdy, Terrence W. Wilcutt is the pilot, and the three mission specialists are Jay Apt, Thomas D. Akers and Carl E. Walz.

  11. Aeroacoustic characterization of scaled canonical nose landing gear configurations

    NASA Astrophysics Data System (ADS)

    Zawodny, Nikolas S.

    Aircraft noise is a critical issue in the commercial airline industry. Airframe noise is a subcomponent of aircraft noise and is generally dominant over jet engine noise during approach conditions, which can lead to high community impact. Landing gears have been identified as major components of airframe noise during landing configurations for commercial aircraft. They are perhaps the least understood contributors to airframe noise due to complex flow patterns associated with intricate gear component geometries. Nose landing gear in particular have received much attention in recent years, exhibiting acoustic signatures on the order of the main landing gear assembly of an aircraft, while simultaneously being more amenable to scaled wind tunnel testing. In order to characterize the acoustic signature of a complex geometry such as a nose landing gear, it is important to isolate, study, and understand the acoustic contributions of individual component geometries. The purpose of this dissertation is to develop a correlation between the complex flow field nature and far-field acoustic signature of a nose landing gear sub-system. The model under investigation is a 1/2-scale shock-strut cylinder coupled with an adjustable torque link apparatus. This geometry was chosen due to its fundamental importance and implementation across a wide span of commercial aircraft. The fluid dynamic (surface pressure and stereoscopic particle image velocimety) and aeroacoustic (far-field microphone and phased array) experiments were performed in the University of Florida Aeroacoustic Flow Facility. The experimental data compare favorably with the results of a numerical simulation using PowerFLOW, a lattice-Boltzmann solver developed by the Exa Corporation. The far-field acoustic results of this dissertation have shown non-uniform scaling behavior as a function of frequency for the different model configurations tested. For frequencies that appropriately satisfied the condition of acoustic

  12. Characteristics of a Lunar Landing Configuration Having Various Multiple-Leg Landing-Gear Arrangements

    NASA Technical Reports Server (NTRS)

    Blanchard, Ulysse J.

    1963-01-01

    An experimental investigation has been made of some lunar-landing characteristics of a 1/6-scale dynamic model of a landing module having multiple-leg landing-gear systems. Symmetric four-point and five-point systems and an asymmetric four-point system were investigated. The landing-gear legs were inverted tripod arrangements having a telescoping main strut which incorporated a yielding-metal strap for energy dissipation, hinged V-struts, and circular pads. The landing tests were made by launching a free model onto an impenetrable hard surface (concrete) and onto a powdered-pumice overlay of various depths. Landing motion and acceleration data were obtained for a range of touchdown speeds, touchdown speeds, touch attitudes, and landing-surface conditions. Symmetric four-point and five-point systems and an Maximum normal acceleration experienced at the module center of gravity during landings on hard surface or pumice was 2g (full-scale lunar value in terms of earth's gravity) over a wide range of touchdown conditions. Maximum angular acceleration experienced was 12-1/2 radians/sec(exp 2) and maximum longitudinal acceleration was 1-3/4 g. The module was very stable with all gear configurations during landings on hard surface (coefficient of friction, microns=0.4) at all conditions tested. Some overturn instability occurred during landings on powdered pumice (microns=0.7 to 1.0) depending upon flight path, pitch and yaw attitude, depth of pumice, surface topography, and landing-gear configuration. The effect of stability of roll attitude for the limited amount of roll-attitude landing data obtained was insignificant. Compared with the four-point system, the five-point system with equal maximum gear radius increased landing stability slightly and improved the static stability for subsequent lunar launch. A considerable increase in landing stability in the direction of motion was obtained with an asymmetric four-point gear having two pads offset to increase gear radius

  13. 14 CFR 23.729 - Landing gear extension and retraction system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... use of hydraulic pressure) to keep the landing gear extended. (c) Emergency operation. For a landplane... operation system; or (2) Any reasonably probable failure in a power source that would prevent the operation... closed beyond the power settings normally used for landing approach if the landing gear is not...

  14. 14 CFR 23.729 - Landing gear extension and retraction system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... use of hydraulic pressure) to keep the landing gear extended. (c) Emergency operation. For a landplane... operation system; or (2) Any reasonably probable failure in a power source that would prevent the operation... closed beyond the power settings normally used for landing approach if the landing gear is not...

  15. Closeup view of the nose and landing gear on the ...

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

    Close-up view of the nose and landing gear on the forward section of the Orbiter Discovery in the Orbiter Processing Facility at Kennedy Space Center. The Orbiter is being supported by jack stands in the left and right portion of the view. The jack stands attach to the Orbiter at the four hoist attach points, two located on the forward fuselage and two on the aft fuselage. Note the access platforms that surround and nearly touch the orbiter. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

  16. Optimisation of shimmy suppression device in an aircraft main landing gear

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Jiang, Jason Zheng; Neild, Simon

    2016-09-01

    In earlier publications of landing gear shimmy analysis, efforts have concentrated on predicting the onset of shimmy instability and investigating how to stabilise shimmy-prone landing gears. Less attention has been given to the improvements of shimmy performance for a gear that is free from dynamic instability. This is the main interest of this work. We investigate the effectiveness of a linear passive mechanical device that consists of springs, dampers and inerters on suppressing landing gear shimmy oscillations. A linear model of a Fokker 100 main landing gear and two configurations of candidate shimmy suppression device have been presented. Considering the physical shimmy motions, time-domain optimisation of the parameters in the shimmy suppression devices, using a cost function of maximum amplitude of gear torsional-yaw motion, has been carried out. The performance advantage of a shimmy suppression device incorporating inerter has been presented.

  17. Appraisal of boundary layer trips for landing gear testing

    NASA Astrophysics Data System (ADS)

    McCarthy, Philip; Feltham, Graham; Ekmekci, Alis

    2013-11-01

    Dynamic similarity during scaled model testing is difficult to maintain. Forced boundary layer transition via a surface protuberance is a common method used to address this issue, however few guidelines exist for the effective tripping of complex geometries, such as aircraft landing gears. To address this shortcoming, preliminary wind tunnel tests were performed at Re = 500,000. Surface transition visualisation and pressure measurements show that zigzag type trips of a given size and location are effective at promoting transition, thus preventing the formation of laminar separation bubbles and increasing the effective Reynolds number from the critical regime to the supercritical regime. Extension of these experiments to include three additional tripping methods (wires, roughness strips, CADCUT dots) in a range of sizes, at Reynolds number of 200,000 and below, have been performed in a recirculating water channel. Analysis of surface pressure measurements and time resolved PIV for each trip device, size and location has established a set of recommendations for successful use of tripping for future, low Reynolds number landing gear testing.

  18. Flow Visualization around a Simplified Two-Wheel Landing Gear

    NASA Astrophysics Data System (ADS)

    Ekmekci, Alis; Feltham, Graham

    2013-11-01

    The flow topology around a simplified two-wheel landing gear model is investigated experimentally by employing the hydrogen bubble flow visualization technique in a recirculating water channel. The landing gear test model consists of two identical wheels, an axle, a main strut and a support strut. The flow Reynolds number based on wheel diameter is 31,500 and wheels with varying geometric details are considered. Flow structures have been identified through analysis of long-time video recordings and linked to the model geometry. In the flow region above the wheels (wing side), the flow in the inter-wheel region either separates prematurely from the inner surfaces of the wheels and forms slant vortices in the near-wake, or remains attached till the aft wheel perimeter. Inclusion of interior wheel wells are found to result in a jet-like ejection as a result of the interaction with the axle and main strut. In the flow region below the wheels (ground side) the near wake contains periodically forming, complex, large-scale structures.

  19. Stability of Castering Wheels for Aircraft Landing Gears, Special Report

    NASA Technical Reports Server (NTRS)

    Kantrowitz, Arthur

    1937-01-01

    In many installations of castering rubber-tired wheels there is a tendency for the wheel to oscillate violently about the spindle axis. This phenomenon, popularly called 'shimmy,' has occurred in some airplane tail wheels and has been corrected in two ways: first by the application of friction in the spindles of the tail wheels; and, second, by locking the wheels while taxiing at high speeds. Shimmy is common with the large wheels used as nose wheels in tricycle landing gears and, since it is impossible to lock the wheels, friction in the nose-wheel spindle has been the sole means of correction. Because the nose wheel is larger than the conventional tail wheel and usually carries a greater load, the larger amounts of spindle friction necessary to prevent shimmy are objectionable. the present paper presents a theoretical and experimental study of the problem of the stability of castering wheels for airplane landing gears. On the basis of simplified assumptions induced from experimental observations, a theoretical study has been made of the shimmy of castering wheels. The theory is based on the discovery of a phenomenon called 'kinematic shimmy' and is compared quantitatively with the results of model experiments. Experimental checks, using a model having low-pressure tires, are reported and the applicability of the results to full scale is discussed. Theoretical methods of estimating the spindle viscous damping and spindle solid friction necessary to avoid shimmy - lateral freedom - is introduced.

  20. Gearing

    NASA Technical Reports Server (NTRS)

    Coy, J. J.; Townsend, D. P.; Zaretsky, E. V.

    1985-01-01

    Gearing technology in its modern form has a history of only 100 years. However, the earliest form of gearing can probably be traced back to fourth century B.C. Greece. Current gear practice and recent advances in the technology are drawn together. The history of gearing is reviewed briefly in the Introduction. Subsequent sections describe types of gearing and their geometry, processing, and manufacture. Both conventional and more recent methods of determining gear stress and deflections are considered. The subjects of life prediction and lubrication are additions to the literature. New and more complete methods of power loss predictions as well as an optimum design of spur gear meshes are described. Conventional and new types of power transmission systems are presented.

  1. STS-26 Discovery, OV-103, with landing gear deployed glides above EAFB runway

    NASA Technical Reports Server (NTRS)

    1988-01-01

    STS-26 Discovery, Orbiter Vehicle (OV) 103, with nose landing gear (NLG) and main landing gear (MLG) deployed glides above dry lakebed runway 17 at Edwards Air Force Base (EAFB), California. This profile view shows OV-103's port side just before MLG touchdown.

  2. STS-26 Discovery, OV-103, with landing gear deployed glides above EAFB runway

    NASA Technical Reports Server (NTRS)

    1988-01-01

    STS-26 Discovery, Orbiter Vehicle (OV) 103, with nose landing gear (NLG) and main landing gear (MLG) deployed glides above dry lakebed runway 17 at Edwards Air Force Base (EAFB), California. This profile view shows the OV-103's starboard side just before MLG touchdown.

  3. STS-26 Discovery, OV-103, with landing gear deployed glides above EAFB runway

    NASA Technical Reports Server (NTRS)

    1988-01-01

    STS-26 Discovery, Orbiter Vehicle (OV) 103, with nose landing gear (NLG) and main landing gear (MLG) deployed glides above dry lakebed runway 17 at Edwards Air Force Base (EAFB), California. This profile view shows the OV-103's port side just before MLG touchdown.

  4. 77 FR 27663 - Airworthiness Directives; Aeronautical Accessories, Inc. High Landing Gear Forward Crosstube...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-11

    ... Accessories, Inc. High Landing Gear Forward Crosstube Assembly AGENCY: Federal Aviation Administration (FAA... directive (AD) for Aeronautical Accessories, Inc. (AAI) high landing gear forward crosstube assemblies.... (Bell) Model 205A, 205A-1, 205B, 212, 412, 412CF, and 412EP helicopters during production or based on...

  5. 77 FR 37768 - Airworthiness Directives; Aeronautical Accessories, Inc., High Landing Gear Aft Crosstube Assembly

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-25

    ... Accessories, Inc., High Landing Gear Aft Crosstube Assembly AGENCY: Federal Aviation Administration (FAA), DOT... Accessories, Inc. (AAI), High Landing Gear Aft Crosstube Assembly (aft crosstube) installed on certain Bell... installed during production or based on a Supplemental Type Certificate (STC). This AD requires...

  6. 77 FR 5420 - Airworthiness Directives; Aeronautical Accessories Inc. High Landing Gear Aft Crosstube Assembly

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ... Accessories Inc. High Landing Gear Aft Crosstube Assembly AGENCY: Federal Aviation Administration (FAA), DOT... (AD) for the Aeronautical Accessories Inc. (AAI) High Landing Gear Aft Crosstube Assembly (aft... helicopters as an approved Bell part installed during production or based on a Supplemental Type...

  7. STS-86 Landing (Main Gear Touchdown (from back)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Space Shuttle orbiter Atlantis touches down on Runway 15 of the KSC Shuttle Landing Facility (SLF) to complete the nearly 11- day STS-86 mission. Main gear touchdown was at 5:55:09 p.m. EDT on Oct. 6, 1997. The unofficial mission-elapsed time at main gear touchdown was 10 days, 19 hours, 20 minutes and 50 seconds. The first two landing opportunities on Sunday were waved off because of weather concerns. The 87th Space Shuttle mission was the 40th landing of the Shuttle at KSC. On Sunday evening, the Space Shuttle program reached a milestone: The total flight time of the Shuttle passed the two-year mark. STS-86 was the seventh of nine planned dockings of the Space Shuttle with the Russian Space Station Mir. STS-86 Mission Specialist David A. Wolf replaced NASA astronaut and Mir 24 crew member C. Michael Foale, who has been on the Mir since mid-May. Foale returned to Earth on Atlantis with the remainder of the STS-86 crew. The other crew members are Commander James D. Wetherbee, Pilot Michael J. Bloomfield, and Mission Specialists Wendy B. Lawrence, Scott E. Parazynski, Vladimir Georgievich Titov of the Russian Space Agency, and Jean-Loup J.M. Chretien of the French Space Agency, CNES. Wolf is scheduled to remain on the Mir until the STS-89 Shuttle mission in January. Besides the docking and crew exchange, STS-86 included the transfer of more than three-and-a- half tons of science/logistical equipment and supplies between the two orbiting spacecraft. Parazynski and Titov also conducted a spacewalk while Atlantis and the Mir were docked.

  8. STS-70 landing just before main gear touchdown

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Space Shuttle orbiter Discovery touches down on KSC's Runway 33, marking a successful conclusion to the STS-70 mission. Discovery landed on orbit 143, during the second opportunity of the day. Main gear touchdown was unofficially listed at 8:02 a.m. EDT on July 22, 1995. The orbiter traveled some 3.7 million statute miles during the nearly nine-day flight, which included a one-day extension because of fog and low visibility conditions at the KSC Shuttle Landing Facility. STS-70 was the 24th landing at KSC and the 70th Space Shuttle mission. The five-member crew deployed a Tracking and Data Relay Satellite-G (TDRS-G). Crew members were Commander Terence 'Tom' Henricks, Pilot Kevin R. Kregel, and Mission Specialists Nancy Jane Currie, Donald A. Thomas and Mary Ellen Weber. STS-70 also was the maiden flight of the new Block I orbiter main engine, which flew in the number one position. The other two engines were of the existing Phase II design.

  9. STS-70 landing main gear touchdown (front view)

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Space Shuttle orbiter Discovery touches down on KSC's Runway 33, marking a successful conclusion to the STS-70 mission. Discovery landed on orbit 143, during the second opportunity of the day. Main gear touchdown was unofficially listed at 8:02 a.m. EDT on July 22, 1995. The orbiter traveled some 3.7 million statute miles during the nearly nine-day flight, which included a one-day extension because of fog and low visibility conditions at the KSC Shuttle Landing Facility. STS-70 was the 24th landing at KSC and the 70th Space Shuttle mission. The five-member crew deployed a Tracking and Data Relay Satellite-G (TDRS-G). Crew members were Commander Terence 'Tom' Henricks, Pilot Kevin R. Kregel, and Mission Specialists Nancy Jane Currie, Donald A. Thomas and Mary Ellen Weber. STS-70 also was the maiden flight of the new Block I orbiter main engine, which flew in the number one position. The other two engines were of the existing Phase II design.

  10. STS-73 Landing - Front view main gear touchdown

    NASA Technical Reports Server (NTRS)

    1995-01-01

    A spaceship named Columbia swoops down from the sky, carrying a treasure chest of research samples accumulated over a nearly 16- day spaceflight. Columbia's main gear touched down on Runway 33 of KSC's Shuttle Landing FAcility at 6:45:21 a.m. EST, November 5. Mission STS-73 marked the second flight of the U.S. Microgravity Laboratory (USML-2). A wide diversity of experiments, ranging from materials processing investigations to plant growth, were located in a Spacelab module in the orbiter cargo bay as well as on the middeck. The seven crew members assigned to STS-73 split into two teams to conduct around-the- clock research during the flight, the sixth Shuttle mission of 1995 and the second longest in program history. The mission commander is Kenneth D.Bowersox; Kent V. Rominger is the pilot. Kathryn C. Thornton is the payload commander, and the two mission specialists are Catherine G. Coleman and Michael E. Lopez- Alegria. To obtain the best results from the microgravity research conducted during the mission, two payload specialists, Albert Sacco Jr. and Fred W. Leslie, also were assigned to the crew. STS-73's return marked the fifth end-of-mission landing in Florida this year, and the 26th overall in the history of the Shuttle program.

  11. STS-73 Landing - Side view main gear touchdown

    NASA Technical Reports Server (NTRS)

    1995-01-01

    A spaceship named Columbia swoops down from the sky, carrying a treasure chest of research samples accumulated over a nearly 16- day spaceflight. Columbia's main gear touched down on Runway 33 of KSC's Shuttle Landing FAcility at 6:45:21 a.m. EST, November 5. Mission STS-73 marked the second flight of the U.S. Microgravity Laboratory (USML-2). A wide diversity of experiments, ranging from materials processing investigations to plant growth, were located in a Spacelab module in the orbiter cargo bay as well as on the middeck. The seven crew members assigned to STS-73 split into two teams to conduct around-the- clock research during the flight, the sixth Shuttle mission of 1995 and the second longest in program history. The mission commander is Kenneth D.Bowersox; Kent V. Rominger is the pilot. Kathryn C. Thornton is the payload commander, and the two mission specialists are Catherine G. Coleman and Michael E. Lopez- Alegria. To obtain the best results from the microgravity research conducted during the mission, two payload specialists, Albert Sacco Jr. and Fred W. Leslie, also were assigned to the crew. STS-73's return marked the fifth end-of-mission landing in Florida this year, and the 26th overall in the history of the Shuttle program.

  12. Vorticity amplification near the stagnation point of landing gear wheels

    NASA Astrophysics Data System (ADS)

    Feltham, G.; Ekmekci, A.

    2014-04-01

    The vicinity near the forward stagnation point of landing-gear wheels has been found to support a mechanism for oncoming streams of weak vorticity to collect, grow, and amplify into discrete large-scale vortical structures that then shed with a distinct periodicity. To the authors' knowledge, such a flow phenomenon has never been reported before for landing gear wheels, which are in essence finite (three-dimensional) cylinders. To gain further insight into this phenomenon, a detailed experimental study has been undertaken employing the hydrogen bubble visualization and Particle Image Velocimetry techniques. A very thin platinum wire, similar to those used in hydrogen bubble visualization applications, was placed upstream of the wheel model to produce two streams of weak vorticity (with opposite sign) that convected toward the model. As the vorticity streams enter the stagnation region of the wheels, significant flow deceleration and vorticity stretching act to collect, grow, and amplify the incoming vorticity streams into large-scale vortical structures. Experiments were performed at a fixed Reynolds number, with a value of 32 500 when defined based on the diameter of the wheel and a value of 21 based on the diameter of the vorticity-generating upstream wire. First, to establish a baseline, the natural flow field (without the presence of an upstream wire) was characterized, where experimentally determined values for the stagnation boundary-layer thickness and the velocity profile along the stagnation streamline were both found to agree with the values provided in the literature for two-dimensional cylinders. Subsequently, the dynamics of vorticity collection, growth, amplification, and shedding were studied. The size, stand-off distance and the shedding frequency of the vortical structures forming near the stagnation region were all found to strongly depend on the impingement location of the inbound vorticity on the wheel. A simple relationship between the non

  13. Modeling the Behaviour of an Advanced Material Based Smart Landing Gear System for Aerospace Vehicles

    SciTech Connect

    Varughese, Byji; Dayananda, G. N.; Rao, M. Subba

    2008-07-29

    The last two decades have seen a substantial rise in the use of advanced materials such as polymer composites for aerospace structural applications. In more recent years there has been a concerted effort to integrate materials, which mimic biological functions (referred to as smart materials) with polymeric composites. Prominent among smart materials are shape memory alloys, which possess both actuating and sensory functions that can be realized simultaneously. The proper characterization and modeling of advanced and smart materials holds the key to the design and development of efficient smart devices/systems. This paper focuses on the material characterization; modeling and validation of the model in relation to the development of a Shape Memory Alloy (SMA) based smart landing gear (with high energy dissipation features) for a semi rigid radio controlled airship (RC-blimp). The Super Elastic (SE) SMA element is configured in such a way that it is forced into a tensile mode of high elastic deformation. The smart landing gear comprises of a landing beam, an arch and a super elastic Nickel-Titanium (Ni-Ti) SMA element. The landing gear is primarily made of polymer carbon composites, which possess high specific stiffness and high specific strength compared to conventional materials, and are therefore ideally suited for the design and development of an efficient skid landing gear system with good energy dissipation characteristics. The development of the smart landing gear in relation to a conventional metal landing gear design is also dealt with.

  14. Modeling the Behaviour of an Advanced Material Based Smart Landing Gear System for Aerospace Vehicles

    NASA Astrophysics Data System (ADS)

    Varughese, Byji; Dayananda, G. N.; Rao, M. Subba

    2008-07-01

    The last two decades have seen a substantial rise in the use of advanced materials such as polymer composites for aerospace structural applications. In more recent years there has been a concerted effort to integrate materials, which mimic biological functions (referred to as smart materials) with polymeric composites. Prominent among smart materials are shape memory alloys, which possess both actuating and sensory functions that can be realized simultaneously. The proper characterization and modeling of advanced and smart materials holds the key to the design and development of efficient smart devices/systems. This paper focuses on the material characterization; modeling and validation of the model in relation to the development of a Shape Memory Alloy (SMA) based smart landing gear (with high energy dissipation features) for a semi rigid radio controlled airship (RC-blimp). The Super Elastic (SE) SMA element is configured in such a way that it is forced into a tensile mode of high elastic deformation. The smart landing gear comprises of a landing beam, an arch and a super elastic Nickel-Titanium (Ni-Ti) SMA element. The landing gear is primarily made of polymer carbon composites, which possess high specific stiffness and high specific strength compared to conventional materials, and are therefore ideally suited for the design and development of an efficient skid landing gear system with good energy dissipation characteristics. The development of the smart landing gear in relation to a conventional metal landing gear design is also dealt with.

  15. The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears - III

    NASA Technical Reports Server (NTRS)

    Herrnstein, William H , Jr; Biermann, David

    1936-01-01

    The tests reported in this report conclude the investigation of landing-gear drag that has been carried out in the NACA 20-foot wind tunnel. They supplement earlier tests (reported in Technical Report No. 485) made with full-scale dummy wheels, wheel fairings, and landing gears intended for airplanes of 3,000 pounds gross weight and include tests of tail wheels and tail skids.

  16. Altus I aircraft in flight, retracting landing gear after takeoff

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The landing gear of the remotely piloted Altus I aircraft retracts into the fuselage after takeoff from Rogers Dry Lake adjacent to NASA's Dryden Flight Research Center, Edwards, Calif. The short series of test flights sponsored by the Naval Postgraduate School in early August, 1997, was designed to demonstrate the ability of the experimental craft to cruise at altitudes above 40,000 feet for sustained durations. On its final flight Aug. 15, the Altus I reached an altitude of 43,500 feet. The Altus I and its sister ship, the Altus II, are variants of the Predator surveillance drone built by General Atomics/Aeronautical Systems, Inc. They are designed for high-altitude, long-duration scientific sampling missions. The Altus I incorporates a single-stage turbocharger, while the Altus II, built for NASA's Environmental Research Aircraft and Sensor Technology project, sports a two-stage turbocharger to enable the craft to fly at altitudes above 55,000 feet.

  17. Landing Gear Integration in Aircraft Conceptual Design. Revision

    NASA Technical Reports Server (NTRS)

    Chai, Sonny T.; Mason, William H.

    1997-01-01

    The design of the landing gear is one of the more fundamental aspects of aircraft design. The design and integration process encompasses numerous engineering disciplines, e.g., structure, weights, runway design, and economics, and has become extremely sophisticated in the last few decades. Although the design process is well-documented, no attempt has been made until now in the development of a design methodology that can be used within an automated environment. As a result, the process remains to be a key responsibility for the configuration designer and is largely experience-based and graphically-oriented. However, as industry and government try to incorporate multidisciplinary design optimization (MDO) methods in the conceptual design phase, the need for a more systematic procedure has become apparent. The development of an MDO-capable design methodology as described in this work is focused on providing the conceptual designer with tools to help automate the disciplinary analyses, i.e., geometry, kinematics, flotation, and weight. Documented design procedures and analyses were examined to determine their applicability, and to ensure compliance with current practices and regulations. Using the latest information as obtained from industry during initial industry survey, the analyses were in terms modified and expanded to accommodate the design criteria associated with the advanced large subsonic transports. Algorithms were then developed based on the updated analysis procedures to be incorporated into existing MDO codes.

  18. Simulation of Aircraft Landing Gears with a Nonlinear Dynamic Finite Element Code

    NASA Technical Reports Server (NTRS)

    Lyle, Karen H.; Jackson, Karen E.; Fasanella, Edwin L.

    2000-01-01

    Recent advances in computational speed have made aircraft and spacecraft crash simulations using an explicit, nonlinear, transient-dynamic, finite element analysis code more feasible. This paper describes the development of a simple landing gear model, which accurately simulates the energy absorbed by the gear without adding substantial complexity to the model. For a crash model, the landing gear response is approximated with a spring where the force applied to the fuselage is computed in a user-written subroutine. Helicopter crash simulations using this approach are compared with previously acquired experimental data from a full-scale crash test of a composite helicopter.

  19. 14 CFR 29.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .... Rotorcraft with landing gear with two wheels forward and one wheel aft of the center of gravity must be... be resisted by angular inertia forces. (c) Level landing attitude with all wheels contacting the... gravity; or (2) The probability of landing with initial contact on the rear wheel must be shown to...

  20. 14 CFR 27.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .... Rotorcraft with landing gear with two wheels forward, and one wheel aft, of the center of gravity must be... be resisted by angular inertia forces. (c) Level landing attitude with all wheels contacting the... gravity; or (2) The probability of landing with initial contact on the rear wheel must be shown to...

  1. Magnetorheological fluids and applications to adaptive landing gear for a lightweight helicopter

    NASA Astrophysics Data System (ADS)

    Ahure-Powell, Louise A.

    During hard landing or crash events of a helicopter there are impact loads that can be injurious to crew and other occupants as well as damaging to the helicopter structure. Landing gear systems are the first in line to protect crew and passengers from detrimental crash loads. The main focus of this research is to improve landing gear systems of a lightweight helicopter. Magnetorheological fluids (MRFs) provide potential solutions to several engineering challenges in a broad range of applications. One application that has been considered recently is the use of magnetorheological (MR) dampers in helicopter landing gear systems. In such application, the adaptive landing gear systems have to continuously adjust their stroking load in response to various operating conditions. In order to support this rotorcraft application, there is a necessity to validate that MRFs are qualified for landing gear applications. First, MRF composites, synthesized utilizing three hydraulic oils certified for use in landing gear systems, two average diameters of spherical magnetic particles, and a lecithin surfactant, are formulated to investigate their performance for potential use in a helicopter landing gear. The magnetorheology of these MR fluids is characterized through a range of tests, including (a) magnetorheology (yield stress and viscosity) as a function of magnetic field, (b) sedimentation analysis using an inductance-based sensor, (c) cycling of a small-scale MR damper undergoing sinusoidal excitations (at 2.5 and 5 Hz), and (d) impact testing of an MR damper for a range of magnetic field strengths and velocities using a free-flight drop tower facility. The performance of these MR fluids was analyzed, and their behavior was compared to standard commercial MR fluids. Based on this range of tests used to characterize the MR fluids synthesized, it was shown that it is feasible to utilize certified landing gear hydraulic oils as the carrier fluids to make suitable MR fluids

  2. Nonlinear modeling of adaptive magnetorheological landing gear dampers under impact conditions

    NASA Astrophysics Data System (ADS)

    Ahuré Powell, Louise A.; Choi, Young T.; Hu, Wei; Wereley, Norman M.

    2016-11-01

    Adaptive landing gear dampers that can continuously adjust their stroking load in response to various operating conditions have been investigated for improving the landing performance of a lightweight helicopter. In prior work, adaptive magnetorheological (MR) landing gear dampers that maintained a constant peak stroking force of 4000 lbf across sink rates ranging from 6 to 12 ft s‑1 were designed, fabricated and successfully tested. In this follow-on effort, it is desired to expand the high end of the sink rate range to hold the peak stroking load constant for sink rates ranging from 6 to 26 ft s‑1, thus extending the high end of the speed range from 12 (in the first study) to 26 ft s‑1. To achieve this increase, a spring-based relief valve MR landing gear damper was developed. In order to better understand the MR landing gear damper behavior, a modified nonlinear Bingham Plastic model was formulated, and it incorporates Darcy friction, viscous forces across the MR and relief valves to better account for the damper force behavior at higher speeds. In addition, gas pressure inside the MR damper piston is considered so the total damper force includes a gas force. The MR landing gear damper performance is characterized using drop tests, and the experiments are used to validate model predictions data at low and high nominal impact speeds up to 26 ft s‑1 (shaft velocity of 9.6 ft s‑1).

  3. ANOPP Landing Gear Noise Prediction Comparisons to Model-scale Data

    NASA Technical Reports Server (NTRS)

    Burley, Casey L.; Brooks, Thomas F.; Humphreys, William M., Jr.; Rawls, John W., Jr.

    2007-01-01

    The NASA Aircraft NOise Prediction Program (ANOPP) includes two methods for computing the noise from landing gear: the "Fink" method and the "Guo" method. Both methods have been predominately validated and used to predict full-scale landing gear noise. The two methods are compared, and their ability to predict the noise for model-scale landing gear is investigated. Predictions are made using both the Fink and Guo methods and compared to measured acoustic data obtained for a high-fidelity, 6.3%-scale, Boeing 777 main landing gear. A process is developed by which full-scale predictions can be scaled to compare with model-scale data. The measurements were obtained in the NASA Langley Quiet Flow Facility for a range of Mach numbers at a large number of observer polar (flyover) and azimuthal (sideline) observer angles. Spectra and contours of the measured sound pressure levels as a function of polar and azimuthal angle characterize the directivity of landing gear noise. Comparisons of predicted noise spectra and contours from each ANOPP method are made. Both methods predict comparable amplitudes and trends for the flyover locations, but deviate at the sideline locations. Neither method fully captures the measured noise directivity. The availability of these measured data provides the opportunity to further understand and advance noise prediction capabilities, particularly for noise directivity.

  4. Influence of landing gear flexibility on aircraft performance during ground roll

    NASA Technical Reports Server (NTRS)

    Sivaramakrishnan, M. M.

    1981-01-01

    An analysis is made of the influence of landing gear deflection characteristics on aircraft performance on the ground up to rotation. A quasi-steady dynamic equilibrium state is assumed, including other simplifying assumptions such as calm air conditions and normal aircraft lift and drag. Ground incidence is defined as the angle made by the mean aerodynamic chord of the wing with respect to the ground plane, and equations are given for force and balance which determine the quasi-equilibrium conditions for the aircraft during ground roll. Results indicate that the landing gear deflections lead to a substantial increase in the angle of attack, and the variation in the ground incidence due to landing gear flexibility could be as much as + or - 50%, and the reduction in tail load requirements almost 25%.

  5. Experimental aeroacoustic study of a landing gear in the unsteady flow induced by a propeller

    NASA Astrophysics Data System (ADS)

    Chekiri, Rafik

    An aeroacoustic study of a two-strut, two-wheel, nacelle-mounted landing gear was conducted to investigate the effects of an upstream propeller on the radiated noise. The development of a 1:10.8 scale model based on a Bombardier Q400 aircraft, consisting of a propeller, motor, nacelle, and landing gear assembly is discussed. Comparisons are made between cases with and without an actuated upstream propeller. Far-field microphone measurements out of the airstream are presented to characterize the acoustic effects of each model component. The main strut and wheels of the model were equipped with surface-mounted microphones to measure unsteady pressures. It is shown that the noise signature of the landing gear cannot be observed over the tunnel background noise in the far-field. Unsteady surface pressures on the main strut show dominant peaks related to vortex shedding from the drag strut for both steady and unsteady upstream conditions.

  6. An Assessment of Flap and Main Landing Gear Noise Abatement Concepts

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Humphreys, William M., Jr.; Lockard, David P.

    2015-01-01

    A detailed assessment of the acoustic performance of several noise reduction concepts for aircraft flaps and landing gear is presented. Consideration is given to the best performing concepts within the suite of technologies that were evaluated in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel using an 18 percent scale, semi-span, high-fidelity Gulfstream aircraft model as a test bed. Microphone array measurements were obtained with the model in a landing configuration (flap deflected 39 degrees and the main landing gear deployed or retracted). The effectiveness of each concept over the range of pitch angles, speeds, and directivity angles tested is presented. Comparison of the acoustic spectra, obtained from integration of the beamform maps between the untreated baseline and treated configurations, clearly demonstrates that the flap and gear concepts maintain noise reduction benefits over the entire range of the directivity angles tested.

  7. 34 CFR 694.21 - What are required activities for GEAR UP projects?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 4 2014-07-01 2014-07-01 false What are required activities for GEAR UP projects? 694... READINESS FOR UNDERGRADUATE PROGRAMS (GEAR UP) § 694.21 What are required activities for GEAR UP projects? A... in the GEAR UP program. These services must include the following activities: (a)...

  8. 34 CFR 694.21 - What are required activities for GEAR UP projects?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 4 2012-07-01 2012-07-01 false What are required activities for GEAR UP projects? 694... READINESS FOR UNDERGRADUATE PROGRAMS (GEAR UP) § 694.21 What are required activities for GEAR UP projects? A... in the GEAR UP program. These services must include the following activities: (a)...

  9. 34 CFR 694.21 - What are required activities for GEAR UP projects?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 4 2011-07-01 2011-07-01 false What are required activities for GEAR UP projects? 694... READINESS FOR UNDERGRADUATE PROGRAMS (GEAR UP) § 694.21 What are required activities for GEAR UP projects? A... in the GEAR UP program. These services must include the following activities: (a)...

  10. 34 CFR 694.21 - What are required activities for GEAR UP projects?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 4 2013-07-01 2013-07-01 false What are required activities for GEAR UP projects? 694... READINESS FOR UNDERGRADUATE PROGRAMS (GEAR UP) § 694.21 What are required activities for GEAR UP projects? A... in the GEAR UP program. These services must include the following activities: (a)...

  11. Cross-stream ejection in the inter-wheel region of aircraft landing gears

    NASA Astrophysics Data System (ADS)

    McCarthy, Philip; Ekmekci, Alis

    2014-11-01

    The reduction of aircraft noise is an important challenge currently faced by aircraft manufacturers. During approach and landing, the landing gears contribute a significant proportion of the aircraft generated noise. It is therefore critical that the key noise sources be identified and understood in order for effective mitigation methods to be developed. For a simplified two-wheel nose landing gear, a strong cross stream flow ejection phenomena has been observed to occur in the inter-wheel region in presence of wheel wells. The location and orientation of these flow ejections causes highly unsteady, three dimensional flow between the wheels that may impinge on other landing gear components, thereby potentially acting as a significant noise generator. The effects of changing the inter-wheel geometry (inter-wheel spacing, the wheel well depth and main strut geometry) upon the cross-stream ejection behaviour has been experimentally investigated using both qualitative flow visualisation and quantitative PIV techniques. A summary of the key results will be presented for the three main geometrical parameters under examination and the application of these findings to real life landing gears will be discussed. Thanks to Messier-Bugatti-Dowty and NSERC for their support for this project.

  12. Landing Gear Components Noise Study - PIV and Hot-Wire Measurements

    NASA Technical Reports Server (NTRS)

    Hutcheson, Florence V.; Burley, Casey L.; Stead, Daniel J.; Becker, Lawrence E.; Price, Jennifer L.

    2010-01-01

    PIV and hot-wire measurements of the wake flow from rods and bars are presented. The test models include rods of different diameters and cross sections and a rod juxtaposed to a plate. The latter is representative of the latch door that is attached to an aircraft landing gear when the gear is deployed, while the single and multiple rod configurations tested are representative of some of the various struts and cables configuration present on an aircraft landing gear. The test set up is described and the flow measurements are presented. The effect of model surface treatment and freestream turbulence on the spanwise coherence of the vortex shedding is studied for several rod and bar configurations.

  13. Landing-gear noise prediction using high-order finite difference schemes

    NASA Astrophysics Data System (ADS)

    Liu, Wen; Wook Kim, Jae; Zhang, Xin; Angland, David; Caruelle, Bastien

    2013-07-01

    Aerodynamic noise from a generic two-wheel landing-gear model is predicted by a CFD/FW-H hybrid approach. The unsteady flow-field is computed using a compressible Navier-Stokes solver based on high-order finite difference schemes and a fully structured grid. The calculated time history of the surface pressure data is used in an FW-H solver to predict the far-field noise levels. Both aerodynamic and aeroacoustic results are compared to wind tunnel measurements and are found to be in good agreement. The far-field noise was found to vary with the 6th power of the free-stream velocity. Individual contributions from three components, i.e. wheels, axle and strut of the landing-gear model are also investigated to identify the relative contribution to the total noise by each component. It is found that the wheels are the dominant noise source in general. Strong vortex shedding from the axle is the second major contributor to landing-gear noise. This work is part of Airbus LAnding Gear nOise database for CAA validatiON (LAGOON) program with the general purpose of evaluating current CFD/CAA and experimental techniques for airframe noise prediction.

  14. Group 13, 1990 Astronaut Class candidate Sherlock examines T-38 landing gear

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Astronaut candidate (ASCAN) Nancy J. Sherlock examines T-38A landing gear along with a NASA Staff Pilot during T-38A flight training at Ellington Field located near JSC. Sherlock, along with classmates from the Group 13 1990 Astronaut class, participated in the familiarization session prior to flying aboard the T-38A aircraft.

  15. 14 CFR 23.729 - Landing gear extension and retraction system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... shutoff for the warning device prescribed in this paragraph, the warning system must be designed so that.... There may not be a manual shutoff for this warning device. The flap position sensing unit may be... burst, or rocks, water, and slush that may enter the landing gear bay....

  16. 14 CFR 23.729 - Landing gear extension and retraction system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... shutoff for the warning device prescribed in this paragraph, the warning system must be designed so that.... There may not be a manual shutoff for this warning device. The flap position sensing unit may be... burst, or rocks, water, and slush that may enter the landing gear bay....

  17. 14 CFR 23.729 - Landing gear extension and retraction system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... shutoff for the warning device prescribed in this paragraph, the warning system must be designed so that.... There may not be a manual shutoff for this warning device. The flap position sensing unit may be... burst, or rocks, water, and slush that may enter the landing gear bay....

  18. 77 FR 1614 - Harmonization of Airworthiness Standards for Transport Category Airplanes-Landing Gear Retracting...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-11

    ... Register on January 5, 2011 (76 FR 472). The NPRM proposed to amend the standards for landing gear... Certification Requirements in Supercooled Large Drop, Mixed Phase, and Ice Crystal Icing Conditions (75 FR 37311... stall speed as a reference stall speed instead of the minimum speed obtained in a stalling maneuver...

  19. 77 FR 67261 - Airworthiness Directives; Aeronautical Accessories, Inc., High Landing Gear Forward Crosstube...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ... the crosstubes and replacing them if a crack or other damage exists. This AD was prompted by two...: Discussion On May 11, 2012, at 77 FR 27663, the Federal Register published our notice of proposed rulemaking... landing gear, and subsequent loss of control of the helicopter. The NPRM was prompted by two reports...

  20. An Approach to Designing Passive Self-Leveling Landing Gear with Application to the Lunar Lander

    NASA Technical Reports Server (NTRS)

    Rippere, Troy B.; Wiens, Gloria J.

    2010-01-01

    Once the lunar lander has touched down on the moon problems can occur if the crew module is not level. To mitigate, compliant landing gear provide a solution that would allow the module to be leveled once it has landed on some ground slope. The work presented here uses compliant joints, or flexures, for each leg of the module and optimizes the mechanics of these flexures such that the module can be passively leveled over a range of landing slopes. Preliminary results suggest that for landing on a slope of up to 12 deg the effective slope of the module can be reduced to a maximum of 2.5 deg.

  1. A method for landing gear modeling and simulation with experimental validation

    NASA Technical Reports Server (NTRS)

    Daniels, James N.

    1996-01-01

    This document presents an approach for modeling and simulating landing gear systems. Specifically, a nonlinear model of an A-6 Intruder Main Gear is developed, simulated, and validated against static and dynamic test data. This model includes nonlinear effects such as a polytropic gas model, velocity squared damping, a geometry governed model for the discharge coefficients, stick-slip friction effects and a nonlinear tire spring and damping model. An Adams-Moulton predictor corrector was used to integrate the equations of motion until a discontinuity caused by a stick-slip friction model was reached, at which point, a Runga-Kutta routine integrated past the discontinuity and returned the problem solution back to the predictor corrector. Run times of this software are around 2 mins. per 1 sec. of simulation under dynamic circumstances. To validate the model, engineers at the Aircraft Landing Dynamics facilities at NASA Langley Research Center installed one A-6 main gear on a drop carriage and used a hydraulic shaker table to provide simulated runway inputs to the gear. Model parameters were tuned to produce excellent agreement for many cases.

  2. Acoustic Measurements of a Large Civil Transport Main Landing Gear Model

    NASA Technical Reports Server (NTRS)

    Ravetta, Patricio A.; Khorrami, Mehdi R.; Burdisso, Ricardo A.; Wisda, David M.

    2016-01-01

    Microphone phased array acoustic measurements of a 26 percent-scale, Boeing 777-200 main landing gear model with and without noise reduction fairings installed were obtained in the anechoic configuration of the Virginia Tech Stability Tunnel. Data were acquired at Mach numbers of 0.12, 0.15, and 0.17 with the latter speed used as the nominal test condition. The fully and partially dressed gear with the truck angle set at 13 degrees toe-up landing configuration were the two most extensively tested configurations, serving as the baselines for comparison purposes. Acoustic measurements were also acquired for the same two baseline configurations with the truck angle set at 0 degrees. In addition, a previously tested noise reducing, toboggan-shaped fairing was re-evaluated extensively to address some of the lingering questions regarding the extent of acoustic benefit achievable with this device. The integrated spectra generated from the acoustic source maps reconfirm, in general terms, the previously reported noise reduction performance of the toboggan fairing as installed on an isolated gear. With the recent improvements to the Virginia Tech tunnel acoustic quality and microphone array capabilities, the present measurements provide an additional, higher quality database to the acoustic information available for this gear model.

  3. Evaluation of metal landing gear door assembly selectively reinforced with filamentary composite for space shuttle application

    NASA Technical Reports Server (NTRS)

    Kong, S. J.; Freeman, V. L.

    1972-01-01

    The development and evaluation of a main landing gear door for space shuttle applications are discussed. The door is constructed on composite materials using a rib-stiffened titanium panel selectively reinforced with boron/epoxy composite. A weight comparison between the hybrid design and the all-titanium baseline design showed a weight saving of approximately fifteen percent. Detailed descriptions of the door structure and method of manufacture are presented.

  4. Planar equations of rollout motion for an aircraft with free or steerable landing gears

    NASA Technical Reports Server (NTRS)

    Sleeper, R. K.; Smith, E. G.

    1982-01-01

    Equations were derived for an aircraft in a three-point attitude. Transient tire forces were simulated by delaying the application of forces derived from steady-state considerations. Predicted rollout trajectories were similar to those measured in tests of a small-scale landing-gear model equipped with pneumatic tires (where a laterally sloping runway was used to simulate a crosswind), both with and without nose-wheel steering.

  5. Load-limiting landing gear footpad energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Chris; Tsai, Ted

    1994-01-01

    As a precursor to future manned missions to the moon, an inexpensive, unmanned vehicle that could carry small, scientific payloads to the lunar surface was studied by NASA. The vehicle, called the Common Lunar Lander, required extremely optimized structural systems to increase the potential payload mass. A lightweight energy-absorbing system (LAGFEAS), which also acts as a landing load-limiter was designed to help achieve this optimized structure. Since the versatile and easily tailored system is a load-limiter, it allowed for the structure to be designed independently of the ever-changing landing energy predictions. This paper describes the LAGFEAS system and preliminary verification testing performed at NASA's Johnson Space Center for the Common Lunar Lander program.

  6. STS-85 Discovery Landing at KSC's SLF (main gear touchdown)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    With Commander Curtis L. Brown, Jr. and Pilot Kent V. Rominger at the controls, the Space Shuttle orbiter Discovery touches down on Runway 33 at KSCs Shuttle Landing Facility at 7:07:59 a.m. EDT Aug. 19 to complete the 11-day, 20-hour and 27-minute-long STS-85 mission. The first landing opportunity on Aug. 18 was waved off due to the potential for ground fog. Also onboard the orbiter are Payload Commander N. Jan Davis, Mission Specialist Robert L. Curbeam, Jr., Mission Specialist Stephen K. Robinson and Payload Specialist Bjarni V. Tryggvason. During the 86th Space Shuttle mission, the crew deployed the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite-2 (CRISTA-SPAS-2) free-flyer to conduct research on the Earths middle atmosphere, retrieving it on flight day 9. The crew also conducted investigations with the Manipulator Flight Demonstration (MFD), Technology Applications and Science-1 (TAS- 1) and International Extreme Ultraviolet Hitchhiker-2 (IEH-2) experiments. Robinson also made observations of the comet Hale- Bopp with the Southwest Ultraviolet Imaging System (SWIS) while other members of the crew conducted biological experiments in the orbiters crew cabin. This was the 39th landing at KSC in the history of the Space Shuttle program and the 11th touchdown for Discovery at the space center.

  7. Noise Spectra and Directivity For a Scale-Model Landing Gear

    NASA Technical Reports Server (NTRS)

    Humphreys, William M., Jr.; Brooks, Thomas F.

    2007-01-01

    An extensive experimental study has been conducted to acquire detailed noise spectra and directivity data for a high-fidelity, 6.3%-scale, Boeing 777 main landing gear. The measurements were conducted in the NASA Langley Quiet Flow Facility using a 41-microphone directional array system positioned at a range of polar and azimuthal observer angles with respect to the model. DAMAS (Deconvolution Approach for the Mapping of Acoustic Sources) array processing as well as straightforward individual microphone processing were employed to compile unique flyover and sideline directivity databases for a range of freestream Mach numbers (0.11 - 0.17) covering typical approach conditions. Comprehensive corrections were applied to the test data to account for shear layer ray path and amplitude variations. This allowed proper beamforming at different measurement orientations, as well as directivity presentation in free-field emission coordinates. Four different configurations of the landing gear were tested: a baseline configuration with and without an attached side door, and a noise reduction concept "toboggan" truck fairing with and without side door. DAMAS noise source distributions were determined. Spectral analyses demonstrated that individual microphones could establish model spectra. This finding permitted the determination of unique, spatially-detailed directivity contours of spectral band levels over a hemispherical surface. Spectral scaling for the baseline model confirmed that the acoustic intensity scaled with the expected sixth-power of the Mach number. Finally, comparison of spectra and directivity between the baseline gear and the gear with an attached toboggan indicated that the toboggan fairing may be of some value in reducing gear noise over particular frequency ranges.

  8. Vorticity amplification and its effects on flow separation from simplified landing gear wheels

    NASA Astrophysics Data System (ADS)

    McCarthy, Philip; Feltham, Graham; Ekmekci, Alis

    2015-11-01

    In the presence of weak streams of inbound vorticity, the stagnation region of bluff bodies have been shown to support mechanisms for the collection and amplification of said vorticity into large-scale, discrete vortex structures. For extremely low aspect ratio cylinders, such as those which represent simplified aircraft landing gear wheels, these discrete vortex structures tilt around the sides of the geometry, orientating their axes in the streamwise direction. Once the oncoming vorticity is collected and amplified into discrete vortices, they are shed from the stagnation region and this cycle repeats itself periodically. The present work investigates the effect of the vortex tilting and subsequent shedding on the behaviour of the outboard side flow separation region present on simplified landing gear wheels. Experiments were conducted in a recirculating-type water tunnel on a two-wheel landing gear model, with the upstream vorticity source being a 100 µm platinum wire. Hydrogen bubble visualisations were first used for qualitative understanding of the flow, accompanied by 2D-PIV for vortex identification and tracking of the growth and movement of the observed structures. Finally, the side separation bubble has been characterised using 3D velocity measurements (using V3V). The authors would like to thank Bombardier, Messier-Bugatti-Dowty and NSERC for their support for this project.

  9. STS-73 Landing - Front view prior to Main Gear Touchdown

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The orbiter Columbia returns to Earth, laden with microgravity research samples accumulated over a nearly 16-day spaceflight. Columbia touched down on the first landing opportunity at KSC's Shuttle Landing Facility, Runway 33, at 6:45 a.m. EST. Mission STS-73 marked the second flight of the U.S. Microgravity Laboratory (USML-2). The seven crew members assigned to STS-73 split into two teams to conduct around-the-clock microgravity research in a Spacelab module located in the orbiter payload bay as well as in the orbiter middeck. The mission commander is Kenneth D. Bowersox; Kent V. Rominger is the pilot. Kathryn C. Thornton is the payload commander, and the two mission specialists are Catherine G. Coleman and Michael E. Lopez- Alegria. To obtain the best results from the many experiments conducted during the mission, two payload specialists, Albert Sacco Jr. and Fred W. Leslie, also were assigned to the crew. The STS-73 mission will become the second longest in Shuttle program history, and Columbia -- loaded with research samples and USML-2 hardware -- weighs the most of any orbiter upon return.

  10. STS-94 Columbia Landing at KSC (before main gear touchdown)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Space Shuttle orbiter Columbia glides in for a touchdown on Runway 33 at KSCs Shuttle Landing Facility at approximately 6:46 a.m. EDT with Mission Commander James D. Halsell Jr. and Pilot Susan L. Still at the controls to complete the STS-94 mission. Also on board are Mission Specialist Donald A. Thomas, Mission Specialist Michael L. Gernhardt, Payload Commander Janice Voss, and Payload Specialists Roger K.Crouch and Gregory T. Linteris. During the Microgravity Science Laboratory-1 (MSL-1) mission, the Spacelab module was used to test some of the hardware, facilities and procedures that are planned for use on the International Space Station while the flight crew conducted combustion, protein crystal growth and materials processing experiments. This mission was a reflight of the STS-83 mission that lifted off from KSC in April of this year. That space flight was cut short due to indications of a faulty fuel cell.

  11. Screening of Potential Landing Gear Noise Control Devices at Virginia Tech For QTD II Flight Test

    NASA Technical Reports Server (NTRS)

    Ravetta, Patricio A.; Burdisso, Ricardo A.; Ng, Wing F.; Khorrami, Mehdi R.; Stoker, Robert W.

    2007-01-01

    In support of the QTD II (Quiet Technology Demonstrator) program, aeroacoustic measurements of a 26%-scale, Boeing 777 main landing gear model were conducted in the Virginia Tech Stability Tunnel. The objective of these measurements was to perform risk mitigation studies on noise control devices for a flight test performed at Glasgow, Montana in 2005. The noise control devices were designed to target the primary main gear noise sources as observed in several previous tests. To accomplish this task, devices to reduce noise were built using stereo lithography for landing gear components such as the brakes, the forward cable harness, the shock strut, the door/strut gap and the lower truck. The most promising device was down selected from test results. In subsequent stages, the initial design of the selected lower truck fairing was improved to account for all the implementation constraints encountered in the full-scale airplane. The redesigned truck fairing was then retested to assess the impact of the modifications on the noise reduction potential. From extensive acoustic measurements obtained using a 63-element microphone phased array, acoustic source maps and integrated spectra were generated in order to estimate the noise reduction achievable with each device.

  12. Analysis of Links Positions in Landing Gear Mechanism

    NASA Astrophysics Data System (ADS)

    Brewczyński, D.; Tora, G.

    2014-08-01

    This article contains a kinematic analysis of an aircraft chassis mechanism in a range of positions. The mechanism of the chassis is made up of several smaller subsystems with different functions. The first mechanism is used to eject the chassis before landing (touchdown) and fold it to hatchway after the lift off. The second mechanism is designed to perform rotation of the crossover with the wheel, in order to adjust the position of the wheel to fit it in the limited space in the hold. The third mechanism allows movement of the chassis resulting from the change in length of the damper. To determine the position of the following links of the mechanism calculus of vectors was applied in which unit vectors were used to represent the angular position of the links. The aim of the analysis is to determine the angle of convergence and the angle of heel wheels as a function of the variable length of hydraulic cylinder, length of the shock absorber, length of the regulations rods

  13. An Experimental Investigation of Damaged Arresting Gear Tapes for the Langley Aircraft Landing Dynamics Facility

    NASA Technical Reports Server (NTRS)

    Mason, Angela J.

    1999-01-01

    An experimental investigation was performed on damaged arresting gear tapes at the Langley Aircraft Landing Dynamics Facility. The arrestment system uses five pairs of tapes to bring the test carriage to a halt. The procedure used to determine when to replace the tapes consists of a close evaluation of each of the 10 tapes after each run. During this evaluation, each tape is examined thoroughly and any damage observed on the tape is recorded. If the damaged tape does not pass the inspection, the tape is replaced with a new one. For the past 13 years, the most commonly seen damage types are edge fray damage and transverse damage. Tests were conducted to determine the maximum tensile strength of a damaged arresting gear tape specimen. The data indicate that tapes exhibiting transverse damage can withstand higher loads than tapes with edge fray damage.

  14. Experimental and analytical determination of characteristics affecting light aircraft landing-gear dynamics

    NASA Technical Reports Server (NTRS)

    Fasanella, E. L.; Mcgehee, J. R.; Pappas, M. S.

    1977-01-01

    An experimental and analytical investigation was conducted to determine which characteristics of a light aircraft landing gear influence gear dynamic behavior significantly. The investigation focused particularly on possible modification for load control. Pseudostatic tests were conducted to determine the gear fore-and-aft spring constant, axial friction as a function of drag load, brake pressure-torque characteristics, and tire force-deflection characteristics. To study dynamic tire response, vertical drops were conducted at impact velocities of 1.2, 1.5, and 1.8 m/s onto a level surface; to determine axial-friction effects, a second series of vertical drops were made at 1.5 m/s onto surfaces inclined 5 deg and 10 deg to the horizontal. An average dynamic axial-friction coefficient of 0.15 was obtained by comparing analytical data with inclined surface drop test data. Dynamic strut bending and associated axial friction were found to be severe for the drop tests on the 10 deg surface.

  15. Development of Custom 465® Corrosion-Resisting Steel for Landing Gear Applications

    NASA Astrophysics Data System (ADS)

    Daymond, Benjamin T.; Binot, Nicolas; Schmidt, Michael L.; Preston, Steve; Collins, Richard; Shepherd, Alan

    2016-04-01

    Existing high-strength low-alloy steels have been in place on landing gear for many years owing to their superior strength and cost performance. However, there have been major advances in improving the strength of high-performance corrosion-resisting steels. These materials have superior environmental robustness and remove the need for harmful protective coatings such as chromates and cadmium now on the list for removal under REACH legislation. A UK government-funded collaborative project is underway targeting a refined specification Custom 465® precipitation hardened stainless steel to replace the current material on Airbus A320 family aircraft main landing gear, a main fitting component developed by Messier-Bugatti-Dowty. This is a collaborative project between Airbus, Messier-Bugatti-Dowty, and Carpenter Technology Corporation. An extensive series of coupon tests on four production Heats of the material have been conducted, to obtain a full range of mechanical, fatigue, and corrosion properties. Custom 465® is an excellent replacement to the current material, with comparable tensile strength and fracture toughness, better ductility, and very good general corrosion and stress corrosion cracking resistance. Fatigue performance is the only significant area of deficit with respect to incumbent materials, fatigue initiation being often related to carbo-titanium-nitride particles and cleavage zones.

  16. Aircraft Landing Gear, Ice and Rain Control Systems (Course Outline), Aviation Mechanics 3 (Air Frame):9067.02.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    This document presents an outline for a 135-hour course designed to familiarize the student with operation, inspection, troubleshooting, and repair of aircraft landing gear, ice and rain control systems. It is designed to help the trainee master the knowledge and skills necessary to become an aviation airframe mechanic. The aviation airframe…

  17. HVOF-Deposited WCCoCr as Replacement for Hard Cr in Landing Gear Actuators

    NASA Astrophysics Data System (ADS)

    Agüero, A.; Camón, F.; García de Blas, J.; Del Hoyo, J. C.; Muelas, R.; Santaballa, A.; Ulargui, S.; Vallés, P.

    2011-12-01

    WCCoCr coatings deposited by HVOF can replace hard Cr on landing gear components. Powders with two different WC particle sizes (micro and nano-) and geometries have been employed to study the effects on the coating's properties. Moreover, coatings produced employing two sets of parameters resulting in high and low flame temperatures have been evaluated. Minor differences in microstructure and morphology were observed for the two powders employing the same spraying parameters, but the nano-sized powder exhibited a higher spraying efficiency. However, more significant microstructural changes result when the low- and high-energy spray parameters are used. Moreover, results of various tests which include adhesion, wear, salt fog corrosion resistance, liquid immersion, and axial fatigue strength, indicate that the coatings produced with high-energy flame are similar in behavior. On the other hand, the nanostructured low-energy flame coating exhibited a significantly lower salt fog corrosion resistance.

  18. Application of FUN3D Solver for Aeroacoustics Simulation of a Nose Landing Gear Configuration

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Lockard, David P.; Khorrami, Mehdi R.

    2011-01-01

    Numerical simulations have been performed for a nose landing gear configuration corresponding to the experimental tests conducted in the Basic Aerodynamic Research Tunnel at NASA Langley Research Center. A widely used unstructured grid code, FUN3D, is examined for solving the unsteady flow field associated with this configuration. A series of successively finer unstructured grids has been generated to assess the effect of grid refinement. Solutions have been obtained on purely tetrahedral grids as well as mixed element grids using hybrid RANS/LES turbulence models. The agreement of FUN3D solutions with experimental data on the same size mesh is better on mixed element grids compared to pure tetrahedral grids, and in general improves with grid refinement.

  19. A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism

    PubMed Central

    Knowles, James A. C.; Lowenberg, Mark H.; Neild, Simon A.; Krauskopf, Bernd

    2014-01-01

    This paper discusses the insights that a bifurcation analysis can provide when designing mechanisms. A model, in the form of a set of coupled steady-state equations, can be derived to describe the mechanism. Solutions to this model can be traced through the mechanism's state versus parameter space via numerical continuation, under the simultaneous variation of one or more parameters. With this approach, crucial features in the response surface, such as bifurcation points, can be identified. By numerically continuing these points in the appropriate parameter space, the resulting bifurcation diagram can be used to guide parameter selection and optimization. In this paper, we demonstrate the potential of this technique by considering an aircraft nose landing gear, with a novel locking strategy that uses a combined uplock/downlock mechanism. The landing gear is locked when in the retracted or deployed states. Transitions between these locked states and the unlocked state (where the landing gear is a mechanism) are shown to depend upon the positions of two fold point bifurcations. By performing a two-parameter continuation, the critical points are traced to identify operational boundaries. Following the variation of the fold points through parameter space, a minimum spring stiffness is identified that enables the landing gear to be locked in the retracted state. The bifurcation analysis also shows that the unlocking of a retracted landing gear should use an unlock force measure, rather than a position indicator, to de-couple the effects of the retraction and locking actuators. Overall, the study demonstrates that bifurcation analysis can enhance the understanding of the influence of design choices over a wide operating range where nonlinearity is significant. PMID:25484601

  20. A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism.

    PubMed

    Knowles, James A C; Lowenberg, Mark H; Neild, Simon A; Krauskopf, Bernd

    2014-12-01

    This paper discusses the insights that a bifurcation analysis can provide when designing mechanisms. A model, in the form of a set of coupled steady-state equations, can be derived to describe the mechanism. Solutions to this model can be traced through the mechanism's state versus parameter space via numerical continuation, under the simultaneous variation of one or more parameters. With this approach, crucial features in the response surface, such as bifurcation points, can be identified. By numerically continuing these points in the appropriate parameter space, the resulting bifurcation diagram can be used to guide parameter selection and optimization. In this paper, we demonstrate the potential of this technique by considering an aircraft nose landing gear, with a novel locking strategy that uses a combined uplock/downlock mechanism. The landing gear is locked when in the retracted or deployed states. Transitions between these locked states and the unlocked state (where the landing gear is a mechanism) are shown to depend upon the positions of two fold point bifurcations. By performing a two-parameter continuation, the critical points are traced to identify operational boundaries. Following the variation of the fold points through parameter space, a minimum spring stiffness is identified that enables the landing gear to be locked in the retracted state. The bifurcation analysis also shows that the unlocking of a retracted landing gear should use an unlock force measure, rather than a position indicator, to de-couple the effects of the retraction and locking actuators. Overall, the study demonstrates that bifurcation analysis can enhance the understanding of the influence of design choices over a wide operating range where nonlinearity is significant. PMID:25484601

  1. Testing and analysis of dual-mode adaptive landing gear, taxi mode test system for YF-12A

    NASA Technical Reports Server (NTRS)

    Gamon, M. A.

    1979-01-01

    The effectiveness of a dual mode adaptive landing gear system in reducing the dynamic response of an airplane during ground taxiing was studied. The dynamic taxi tests of the YF-12A research airplane are presented. A digital computer program which simulated the test conditions is discussed. The dual mode system as tested provides dynamic taxi response reductions of 25 percent at the cg and 30 to 45 percent at the cockpit.

  2. Aeroacoustic Simulation of a Nose Landing Gear in an Open Jet Facility Using FUN3D

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Lockhard, David P.; Khorrami, Mehdi R.; Carlson, Jan-Renee

    2012-01-01

    Numerical simulations have been performed for a partially-dressed, cavity-closed nose landing gear configuration that was tested in NASA Langley s closed-wall Basic Aerodynamic Research Tunnel (BART) and in the University of Florida s open-jet acoustic facility known as UFAFF. The unstructured-grid flow solver, FUN3D, developed at NASA Langley Research center is used to compute the unsteady flow field for this configuration. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these computations. Time-averaged and instantaneous solutions compare favorably with the measured data. Unsteady flowfield data obtained from the FUN3D code are used as input to a Ffowcs Williams-Hawkings noise propagation code to compute the sound pressure levels at microphones placed in the farfield. Significant improvement in predicted noise levels is obtained when the flowfield data from the open jet UFAFF simulations is used as compared to the case using flowfield data from the closed-wall BART configuration.

  3. Amplification of Vorticity Near the Stagnation Point of Landing Gear Wheels

    NASA Astrophysics Data System (ADS)

    Feltham, Graham; Ekmekci, Alis

    2013-11-01

    In this experimental investigation, a stream of steady weak vorticity impinging near the stagnation point of a landing gear wheel is shown to grow and amplify into large-scale vortices that coherently shed from the point of generation. To produce the upstream vorticity, a platinum wire of 100 micron diameter, similar to that used in hydrogen bubble visualization technique, is placed upstream of the wheel model. Experiments are conducted in a recirculating water channel. The wheel diameter is D = 152 mm. The Reynolds number based on the wire diameter is 21 and based on the wheel diameter is 32,500. Qualitative understanding of the vorticity amplification and eventual vortex shedding near the stagnation region of the wheel is achieved by employing the hydrogen bubble visualization technique while quantitative insight is collected using Particle Image Velocimetry (PIV). The size and frequency of the shed vortices are found to depend on the wheel geometry as well as the magnitude and impingement point of the inbound vorticity.

  4. Development and Flight Testing of an Autonomous Landing Gear Health-Monitoring System

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Coffey, Neil C.; Gonzalez, Guillermo A.; Taylor, B. Douglas; Brett, Rube R.; Woodman, Keith L.; Weathered, Brenton W.; Rollins, Courtney H.

    2003-01-01

    Development and testing of an adaptable vehicle health-monitoring architecture is presented. The architecture is being developed for a fleet of vehicles. It has three operational levels: one or more remote data acquisition units located throughout the vehicle; a command and control unit located within the vehicle; and, a terminal collection unit to collect analysis results from all vehicles. Each level is capable of performing autonomous analysis with a trained expert system. Communication between all levels is done with wireless radio frequency interfaces. The remote data acquisition unit has an eight channel programmable digital interface that allows the user discretion for choosing type of sensors; number of sensors, sensor sampling rate and sampling duration for each sensor. The architecture provides framework for a tributary analysis. All measurements at the lowest operational level are reduced to provide analysis results necessary to gauge changes from established baselines. These are then collected at the next level to identify any global trends or common features from the prior level. This process is repeated until the results are reduced at the highest operational level. In the framework, only analysis results are forwarded to the next level to reduce telemetry congestion. The system's remote data acquisition hardware and non-analysis software have been flight tested on the NASA Langley B757's main landing gear. The flight tests were performed to validate the following: the wireless radio frequency communication capabilities of the system, the hardware design, command and control; software operation; and, data acquisition, storage and retrieval.

  5. Effect of Vorticity Amplification on Flow Separation from Landing Gear Wheels

    NASA Astrophysics Data System (ADS)

    Feltham, Graham; McCarthy, Philip; Ekmekci, Alis

    2014-11-01

    The flow near the stagnation point of landing gear wheels has been previously shown to support a mechanism for inbound streams of weak vorticity to collect, growth, and amplify into large-scale discrete vortex structures. The current experimental study is an extension to investigate the effects of these vortex structures on the separation characteristics of the flow around the outboard sides of the wheels. Experiments were performed in a water channel with qualitative understanding of the flow topology achieved by employing the hydrogen bubble visualization technique and quantitative measurements performed using Particle Image Velocimetry (PIV). The upstream vorticity source is a platinum wire (d = 100 μm) placed 30 mm upstream of the model wheels. The Reynolds number based on wire diameter is 21 and based on wheel diameter (D = 152 mm) is 32,500. The inbound pair of vorticity streams impinged at the wheel surface where maximum vortex growth and amplification occurs as identified by previous experiments. The growth and shedding of the resulting vortical structures is shown to alter the shape and size of the separation bubbles on the outboard sides of the wheels. A vortex identification and tracking method is applied to map the growth and movement of the observed structures.

  6. Aeroacoustic Simulation of Nose Landing Gear on Adaptive Unstructured Grids With FUN3D

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Khorrami, Mehdi R.; Park, Michael A.; Lockhard, David P.

    2013-01-01

    Numerical simulations have been performed for a partially-dressed, cavity-closed nose landing gear configuration that was tested in NASA Langley s closed-wall Basic Aerodynamic Research Tunnel (BART) and in the University of Florida's open-jet acoustic facility known as the UFAFF. The unstructured-grid flow solver FUN3D, developed at NASA Langley Research center, is used to compute the unsteady flow field for this configuration. Starting with a coarse grid, a series of successively finer grids were generated using the adaptive gridding methodology available in the FUN3D code. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these computations. Time-averaged and instantaneous solutions obtained on these grids are compared with the measured data. In general, the correlation with the experimental data improves with grid refinement. A similar trend is observed for sound pressure levels obtained by using these CFD solutions as input to a FfowcsWilliams-Hawkings noise propagation code to compute the farfield noise levels. In general, the numerical solutions obtained on adapted grids compare well with the hand-tuned enriched fine grid solutions and experimental data. In addition, the grid adaption strategy discussed here simplifies the grid generation process, and results in improved computational efficiency of CFD simulations.

  7. Aeroacoustic Simulations of a Nose Landing Gear Using FUN3D on Pointwise Unstructured Grids

    NASA Technical Reports Server (NTRS)

    Vatsa, Veer N.; Khorrami, Mehdi R.; Rhoads, John; Lockard, David P.

    2015-01-01

    Numerical simulations have been performed for a partially-dressed, cavity-closed (PDCC) nose landing gear configuration that was tested in the University of Florida's open-jet acoustic facility known as the UFAFF. The unstructured-grid flow solver FUN3D is used to compute the unsteady flow field for this configuration. Mixed-element grids generated using the Pointwise(TradeMark) grid generation software are used for these simulations. Particular care is taken to ensure quality cells and proper resolution in critical areas of interest in an effort to minimize errors introduced by numerical artifacts. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence model is used for these simulations. Solutions are also presented for a wall function model coupled to the standard turbulence model. Time-averaged and instantaneous solutions obtained on these Pointwise grids are compared with the measured data and previous numerical solutions. The resulting CFD solutions are used as input to a Ffowcs Williams-Hawkings noise propagation code to compute the farfield noise levels in the flyover and sideline directions. The computed noise levels compare well with previous CFD solutions and experimental data.

  8. In-Service Evaluation of HVOF Coated Main Landing Gear on Navy P-3 Aircraft

    NASA Technical Reports Server (NTRS)

    Devereaux, jon L.; Forrest, Clint

    2008-01-01

    Due to the environmental and health concerns with Electroplated Hard Chrome (EHC), the Hard Chrome Alternatives Team (HCAT) has been working to provide an alternative wear coating for EHC. The US Navy selected Tungsten-Carbide Cobalt (WC- 17Co) High Velocity Oxy-Fuel (HVOF) thermal spray coating for this purpose and completed service evaluations on select aircraft components to support the HCAT charter in identifying an alternative wear coating for chrome plating. Other benefits of WC-Co thermal spray coatings over EHC are enhanced corrosion resistance, improved durability, and exceptional wear properties. As part of the HCAT charter and to evaluate HVOF coatings on operational Navy components, the P-3 aircraft was selected for a service evaluation to determine the coating durability as compared to chrome plating. In April 1999, a VP-30 P-3 aircraft was outfitted with a right-hand Main Landing Gear (MLG) shock strut coated with WCCo HYOF thermal spray applied to the piston barrel and four axle journals. The HVOF coating on the piston barrel and axle journals was applied by Southwest United Industries, Inc. This HVOF coated strut assembly has since completed 6,378 landings. Teardown analysis .for this WC-Co HVOF coated MLG asset is significant in assessing the durability of this wear coating in service relative to EHC and to substantiate Life Cycle Cost (LCC) data to support a retrograde transition from EHC to HVOF thermal spray coatings. Findings from this teardown analysis may also benefit future transitions to HVOF thermal spray coatings by identifying enhancements to finishing techniques, mating bearing and liner material improvements, improved seal materials, and improvements in HVOF coating selection.

  9. Integrated Design of an Active Torque Balancing Mechanism and a Planetary Gear Reducer

    NASA Astrophysics Data System (ADS)

    Sun, Jing; Yao, Yanan

    In this paper, a novel concept of integrating an active torque balancing mechanism with a planetary gear reducer is presented. This integrated device is composed of a speed reduction unit and a torque compensation unit. The speed reduction unit, which contains a two-stage planetary gear train, can make the device to transform the speed and torque for meeting the needed requirements of the machine. The torque compensation unit, which consists of a differential gear train and a servo motor, can make the device to balance the input torque fluctuations of the mechanical system. Through an analytical method, an exact control function which can totally eliminate the input torque fluctuation of the driving motor of the machine is derived for the servo motor of the integrated device. At the same time, by adjusting the structure parameters of the differential gear train, the torque fluctuation of the servo motor can be limited too. Besides, in order to obtain a satisfactory tradeoff between the torque fluctuations of the driving motor and the servo motor, an optimization method is developed to find an appropriate control function for the servo motor. In addition, an integrated approach is proposed to optimize both the structure parameters of the differential gear train and the control function of the servo motor. Two numerical examples are given to illustrate the design procedures and to show their feasibilities.

  10. 78 FR 17188 - Agency Information Collection Activities; Comment Request; Evaluation of the GEAR UP College...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... Agency Information Collection Activities; Comment Request; Evaluation of the GEAR UP College Savings... College Savings Account Research Demonstration. OMB Control Number: 1850--New. Type of Review: A new.... Department of Education (ED) will conduct a demonstration to test the effectiveness of supporting...

  11. 34 CFR 694.22 - What other activities may all GEAR UP projects provide?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 4 2013-07-01 2013-07-01 false What other activities may all GEAR UP projects provide? 694.22 Section 694.22 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION (CONTINUED) GAINING EARLY AWARENESS...

  12. Rosetta Lander - Philae: activities after hibernation and landing preparations

    NASA Astrophysics Data System (ADS)

    Ulamec, Stephan; Biele, Jens; Sierks, Holger; Blazquez, Alejandro; Cozzoni, Barbara; Fantinati, Cinzia; Gaudon, Philippe; Geurts, Koen; Jurado, Eric; Paetz, Brigitte.; Maibaum, Michael

    Rosetta is a Cornerstone Mission of the ESA Horizon 2000 programme. It is going to rendezvous with comet 67P/Churyumov-Gerasimenko after a ten year cruise and will study both its nucleus and coma with an orbiting spacecraft as well as with a Lander, Philae. Aboard Philae, a payload consisting of ten scientific instruments will perform in-situ studies of the cometary material. Rosetta and Philae have been in hibernation until January 20, 2014. After the successful wakeup they will undergo a post hibernation commissioning. The orbiter instruments (like e.g. the OSIRIS cameras) are to characterize the target comet to allow landing site selection and the definition of a separation, descent and landing (SDL) strategy for the Lander. By August 2014 our currently very poor knowledge of the characteristics of the nucleus of the comet will have increased dramatically. The paper will report on the latest updates in Separation-Descent-Landing (SDL) planning. Landing is foreseen for November 2014 at a heliocentric distance of 3 AU. Philae will be separated from the mother spacecraft from a dedicated delivery trajectory. It then descends ballistically to the surface of the comet, stabilized with an internal flywheel. At touch-down anchoring harpoons will be fired and a damping mechanism within the landing gear will provide the lander from re-bouncing. The paper will give an overview of the Philae system, the operational activities after hibernation and the latest status on the preparations for landing.

  13. Opposite selection on behavioural types by active and passive fishing gears in a simulated guppy Poecilia reticulata fishery.

    PubMed

    Diaz Pauli, B; Wiech, M; Heino, M; Utne-Palm, A C

    2015-03-01

    This study assessed whether fishing gear was selective on behavioural traits, such as boldness and activity, and how this was related with a productivity trait, growth. Female guppies Poecilia reticulata were screened for their behaviour on the shy-bold axis and activity, and then tested whether they were captured differently by passive and active fishing gear, here represented by a trap and a trawl. Both gears were selective on boldness; bold individuals were caught faster by the trap, but escaped the trawl more often. Boldness and gear vulnerability showed weak correlations with activity and growth. The results draw attention to the importance of the behavioural dimension of fishing: selective fishing on behavioural traits will change the trait composition of the population, and might eventually affect resilience and fishery productivity.

  14. Opposite selection on behavioural types by active and passive fishing gears in a simulated guppy Poecilia reticulata fishery.

    PubMed

    Diaz Pauli, B; Wiech, M; Heino, M; Utne-Palm, A C

    2015-03-01

    This study assessed whether fishing gear was selective on behavioural traits, such as boldness and activity, and how this was related with a productivity trait, growth. Female guppies Poecilia reticulata were screened for their behaviour on the shy-bold axis and activity, and then tested whether they were captured differently by passive and active fishing gear, here represented by a trap and a trawl. Both gears were selective on boldness; bold individuals were caught faster by the trap, but escaped the trawl more often. Boldness and gear vulnerability showed weak correlations with activity and growth. The results draw attention to the importance of the behavioural dimension of fishing: selective fishing on behavioural traits will change the trait composition of the population, and might eventually affect resilience and fishery productivity. PMID:25619538

  15. Hybrid Gear

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F. (Inventor); Roberts, Gary D. (Inventor)

    2016-01-01

    A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface (hub) and gear tooth rim is described. The composite lay-up lightens the gear member while having similar torque carrying capability and it attenuates the impact loading driven noise/vibration that is typical in gear systems. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design.

  16. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  17. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  18. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  19. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  20. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  1. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  2. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  3. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  4. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  5. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with...

  6. Results of a landing gear loads test using a 0.0405-scale model (16-0) of the space shuttle orbiter in the Rockwell International NAAL wind tunnel (OA163), volume 1

    NASA Technical Reports Server (NTRS)

    Mennell, R. C.

    1976-01-01

    Experimental aerodynamic investigations were conducted on a sting mounted scale representation of the 140C outer mold line space shuttle orbiter configuration in the low speed wind tunnel. The primary test objectives were to define the orbiter landing gear system pressure loading and to record landing gear door and strut hingemoment levels. Secondary objectives included recording the aerodynamic influence of various landing gear configurations on orbiter force data as well as investigating 40 x 80 ft. Ames Wind Tunnel strut simulation effects on both orbiter landing gear loads and aerodynamic characteristics. Testing was conducted at a Mach number of 0.17, free stream dynamic pressure of 42.5 PSF, and Reynolds number per unit length of 1.2 million per foot. Angle of attack variation was 0 to 20 while yaw angles ranged from -10 to 10 deg.

  7. Vorticity amplification near the stagnation point of landing gear wheels: effect of the orientation of the impinging vorticity

    NASA Astrophysics Data System (ADS)

    Gu, Mingyao; Feltham, Graham; Ekmekci, Alis

    2014-11-01

    When oncoming streams of weak vorticity aligned with the axle axis of a two-wheel landing gear impinge near the forward stagnation point of the wheels, a mechanism for vorticity collection, growth, amplification into discrete large-scale vortices, and shedding was formerly shown to exist. In the current study, the impinging vorticity streams are perpendicular to the axle axis, i.e. in a vertical orientation as opposed to the horizontal orientation before. Experiments are conducted in a recirculating water channel using hydrogen bubble visualization and particle image velocimetry at a Reynolds number of 32,500 (based on the wheel diameter). As with the horizontal orientation, vorticity collection and amplification are observed, but the large-scale vortices thus formed are stretched around the wheel circumference in contrast to being stretched around the wheel sides, as observed for the horizontal orientation. This flow behavior varies with the impingement location of the vorticity streams across the wheel width. Maximum vorticity amplification occurs at a critical impingement location and drastically alters the flow separation along the wheel circumference. In addition, the instantaneous vortical structures are identified and tracked using a Galilean-invariant criterion.

  8. Investigation of the Maximum Spin-Up Coefficients of Friction Obtained During Tests of a Landing Gear Having a Static-Load Rating of 20,000 Pounds

    NASA Technical Reports Server (NTRS)

    Batterson, Sidney A.

    1959-01-01

    An experimental investigation was made at the Langley landing loads track to obtain data on the maximum spin-up coefficients of friction developed by a landing gear having a static-load rating of 20,000 pounds. The forward speeds ranged from 0 to approximately 180 feet per second and the sinking speeds, from 2.7 feet per second to 9.4 feet per second. The results indicated the variation of the maximum spin-up coefficient of friction with forward speed and vertical load. Data obtained during this investigation are also compared with some results previously obtained for nonrolling tires to show the effect of forward speed.

  9. Simulations and Experiments of Hot Forging Design and Evaluation of the Aircraft Landing Gear Barrel Al Alloy Structure

    NASA Astrophysics Data System (ADS)

    Ram Prabhu, T.

    2016-04-01

    In the present study, the hot forging design of a typical landing gear barrel was evolved using finite element simulations and validated with experiments. A DEFORM3D software was used to evolve the forging steps to obtain the sound quality part free of defects with minimum press force requirements. The hot forging trial of a barrel structure was carried out in a 30 MN hydraulic press based on the simulation outputs. The tensile properties of the part were evaluated by taking samples from all three orientations (longitudinal, long transverse, short transverse). The hardness and microstructure of the part were also investigated. To study the soundness of the product, fluorescent penetrant inspection and ultrasonic testing were performed in order to identify any potential surface or internal defects in the part. From experiments, it was found that the part was formed successfully without any forging defects such as under filling, laps, or folds that validated the effectiveness of the process simulation. The tensile properties of the part were well above the specification limit (>10%) and the properties variation with respect to the orientation was less than 2.5%. The part has qualified the surface defects level of Mil Std 1907 Grade C and the internal defects level of AMS 2630 Class A (2 mm FBh). The microstructure shows mean grain length and width of 167 and 66 µm in the longitudinal direction. However, microstructure results revealed that the coarse grain structure was observed on the flat surface near the lug region due to the dead zone formation. An innovative and simple method of milling the surface layer after each pressing operation was applied to solve the problem of the surface coarse grain structure.

  10. Differential gearing

    SciTech Connect

    Tamiya, S.

    1986-07-29

    A differential for motor vehicles is described and the like comprising, an input drive shaft, a pair of coaxially spaced drive gears simultaneously driven by the input shaft in a same direction at a same speed of rotation about a common axis of rotation, a driven gear driven peripherally by the pair of drive gears for transmission of power from the input drive shaft, two coaxial opposed bevel sun gears having an axis of rotation concentric with an axis of rotation of the driven gear, two planetary gears disposed between the sun gears for differential driving thereof during turns of the vehicle to the right and to the left of each meshing with the sun gears for driving the suns gears. Each planetary gear has a separate axis of rotation carried by the driven gear disposed therein radially and symmetrically relative to the axis of rotation of the sun gears, and each sun gear having a respective power output shaft connected thereto for rotation therewith.

  11. Effect of noise reducing components on nose landing gear stability for a mid-size aircraft coupled with vortex shedding and freeplay

    NASA Astrophysics Data System (ADS)

    Eret, Petr; Kennedy, John; Bennett, Gareth J.

    2015-10-01

    In the pursuit of quieter aircraft, significant effort has been dedicated to airframe noise identification and reduction. The landing gear is one of the main sources of airframe noise on approach. The addition of noise abatement technologies such as fairings or wheel hub caps is usually considered to be the simplest solution to reduce this noise. After touchdown, noise abatement components can potentially affect the inherently nonlinear and dynamically complex behaviour (shimmy) of landing gear. Moreover, fairings can influence the aerodynamic load on the system and interact with the mechanical freeplay in the torque link. This paper presents a numerical study of nose landing gear stability for a mid-size aircraft with low noise solutions, which are modelled by an increase of the relevant model structural parameters to address a hypothetical effect of additional fairings and wheel hub caps. The study shows that the wheel hub caps are not a threat to stability. A fairing has a destabilising effect due to the increased moment of inertia of the strut and a stabilising effect due to the increased torsional stiffness of the strut. As the torsional stiffness is dependent on the method of attachment, in situations where the fairing increases the torsional inertia with little increase to the torsional stiffness, a net destabilising effect can result. Alternatively, it is possible that for the case that if the fairing were to increase equally both the torsional stiffness and the moment of inertia of the strut, then their effects could be mutually negated. However, it has been found here that for small and simple fairings, typical of current landing gear noise abatement design, their implementation will not affect the dynamics and stability of the system in an operational range (Fz ≤ 50 000 N, V ≤ 100 m/s). This generalisation is strictly dependent on size and installation methods. The aerodynamic load, which would be influenced by the presence of fairings, was modelled

  12. 76 FR 5402 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Gear...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-31

    ... November 5, 2010 (75 FR 68381). Interested parties are encouraged to send comments to the OMB, Office of...; Gear Certification ACTION: Notice. SUMMARY: The Department of Labor (DOL) hereby announces the... request (ICR) titled, ``Gear Certification,'' to the Office of Management and Budget (OMB) for review...

  13. Results of a landing gear loads test using a 0.0405-scale model (16-0) of the space shuttle orbiter in the Rockwell International NAAL wind tunnel (OA163B), volume 1

    NASA Technical Reports Server (NTRS)

    Mennell, R. C.

    1977-01-01

    Aerodynamic loads on a sting mounted 0.045-scale representation of the 140C outer mold line space shuttle orbiter configuration were measured to verify orbiter landing gear system pressure loading and hinge moment levels. Pressure, force, and hinge moment data, recorded over smaller increments of the landing gear deployment schedule to insure data accuracy and to investigate the effects of asymmetric gear deployment on all parameters, are presented. Tests were conducted at a Mach number of 0.17, and freestream dynamic pressure of 42.5 psf, and a Reynolds number per unit length of 1.2 million foot. Angle of attack variation was -2 to 10 degrees while angles of sideslip varied from -5 to 5 degrees.

  14. Study of wear and galling in aircraft fuel pump drive shafts and gears using the surface layer activation technique

    NASA Astrophysics Data System (ADS)

    Gallmann, A.; Natter, B.; Molinari, M. A.

    1988-10-01

    The surface layer activation technique (SLA) has been applied to study galling and wear in moving parts of Boeing 747 engines. Radioactive 56Co was formed by the reaction 56Fe(p, n) 56Co in fuel pump drive shafts and gears, and their residual activities in these activated parts were measured in situ during routine inspections over more than one year. The study of the wear was done on shafts made of a new alloy and on gears having a new tooth geometry. Wear determined by SLA was corroborated by a profile measurement made when one of the pumps was disassembled. The study of the galling (with release of metallic fragments) of a drive shaft consisted in checking the condition of the critical zone of the splines with the SLA technique. The main originality of the present work is that for the first time such measurements were performed on engines in revenue service.

  15. Geared power transmission technology

    NASA Technical Reports Server (NTRS)

    Coy, J. J.

    1983-01-01

    The historical path of the science and art of gearing is reviewed. The present state of gearing technology is discussed along with examples of some of the NASA-sponsored contributions to gearing technology. Future requirements in gearing are summarized.

  16. Transmission gearing arrangement

    SciTech Connect

    Klemen, D.

    1987-08-04

    A gearing arrangement is described for an automotive power transmission comprising: an input shaft and an output shaft; first, second, and third simple planetary gear sets. Each has a sun gear, a ring gear, and a planet gears meshing with the sun and the ring gears and rotatably supported on a planet carrier; means rigidly interconnecting the ring gear of the third gear set and the carrier of the second gear set; means rigidly interconnecting the ring gear of the second gear set and the carrier of the first gear set; means rigidly connecting the output shaft and the carrier of the third gear set; a first intermediate shaft rigidly interconnecting the sun gears of the second and the third gear sets for unitary rotation; a second intermediate shaft rigidly connected to the carrier of the second gear set; a third intermediate shaft continuously connected to the input shaft and to the sun gear of the first gear set; first, second, and third brake means operative to selectively brake rotation of the ring gears of the first, the second, and the third gear sets, respectively; a first rotating clutch selectively operable to connect the input shaft and the first intermediate shaft for unitary rotation; a second rotating clutch selectively operable to connect the input shaft and the second intermediate shaft for unitary rotation; a fourth simple planetary gear set including a sun gear and a ring gear and planet gears meshing with the sun and the ring gears and rotatably supported on a planet carrier; means rigidly connecting the sun gear of the fourth gear set to the third intermediate shaft; means rigidly connecting the ring gear of the fourth gear set to the carrier of the first gear set; and a fourth brake means selectively operable to brake the carrier of the fourth gear set. The nine forward ratios are obtainable while preserving a single transition shifting over the entire nine forward ratios.

  17. 50 CFR 648.144 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF COMMERCE FISHERIES OF THE NORTHEASTERN UNITED STATES Management Measures for the Black Sea Bass Fishery § 648.144 Gear restrictions. (a) Trawl gear restrictions—(1) General. (i) Otter trawlers whose owners are issued a black sea bass moratorium permit and that land or possess 500 lb (226.8 kg) or...

  18. Flex-Gears

    NASA Technical Reports Server (NTRS)

    Tsai, Lung-Wen; Peritt, Jonathan

    1993-01-01

    Flex-Gears are being developed as an alternative to brushes and slip rings to conduct electricity across a rotating joint. Flex-Gears roll in the annulus of sun and ring gears for electrical contact while maintaining their position by using a novel application of involute gears. A single Flex-Gear is predicted to transfer up to 2.8 amps, thereby allowing a six inch diameter device, holding 30 Flex-Gears, to transfer over 80 amps. Semi-rigid Flex-Gears are proposed to decrease Flex-Gear stress and insure proper gear meshing.

  19. Gear box assembly

    SciTech Connect

    Harrod, L.R.; Siebern, M.R.

    1989-04-25

    This patent describes a gearbox assembly for a vehicle which includes a driven axle shaft extending transversely of the vehicle having wheels secured thereto: a drive gear concentric with the axle shaft nonrotatably connected to the shaft, the drive gear having an integral hub on each of opposite sides thereof, a pinion gear shiftably mounted above the drive gear having one position engaging the drive gear and shiftable laterally to disengage from the drive gear, a shift lever mounted in a position projecting upwardly from the pinion gear actuatable to shift the pinion gear, an electric motor with output shaft mounted with the output shaft paralleling the axle shaft and having a driving gear mounted thereon, a multiple gear gear train mounted so as to establish a driving connection between the driving gear and the pinion gear, and a transmission housing enclosing the driving gar, gear train, pinion gear and drive gear, the housing including sleeve portions rotatably receiving the hubs of the drive gear and thus rotatably mounting the drive gear and the axle shaft connected to the drive gear.

  20. Directional gear ratio transmissions

    NASA Technical Reports Server (NTRS)

    Lafever, A. E. (Inventor)

    1984-01-01

    Epicyclic gear transmissions which transmit output at a gear ratio dependent only upon the input's direction are considered. A transmission housing envelops two epicyclic gear assemblies, and has shafts extending from it. One shaft is attached to a sun gear within the first epicyclic gear assembly. Planet gears are held symmetrically about the sun gear by a planet gear carrier and are in mesh with both the sun gear and a ring gear. Two unidirectional clutches restrict rotation of the first planet gear carrier and ring gear to one direction. A connecting shaft drives a second sun gear at the same speed and direction as the first planet gear carrier while a connecting portion drives a second planet gear carrier at the same speed and direction as the first ring gear. The transmission's output is then transmitted by the second ring gear to the second shaft. Input is transmitted at a higher gear ratio and lower speed for all inputs in the first direction than in the opposite direction.

  1. Planetary gear train

    SciTech Connect

    Hiraiwa, K.

    1988-10-04

    A planetary gear train is described comprising: an input member; an output member; a first planetary gear set including a first sun gear, a first ring gear, and a first pinion carrier rotatably supporting first planet pinions; a secondary planetary gear set including a second sun gear, and second ring gear and a second pinion carrier rotatably supporting second planet pinions; first drive means for connecting the input member with the first ring gear; second drive means for connecting the input member with the first sun gear; third drive means for constantly connecting the first sun gear with the second sun gear and establishing a force transmitting positive drive from the first sun gear to the second sun gear, whereby the first sun gear rotates at a speed different from the second sun gear; first brake means for braking the second sun gear; second brake means for braking the second pinion carrier; fourth drive means for connecting the second ring gear with the output member and providing a first speed ratio therebetween; and fifth drive means for connecting the first pinion carrier with the output member and providing a second speed ratio therebetween, the second speed ratio being different from the first speed ratio.

  2. Gear tooth topological modification

    NASA Technical Reports Server (NTRS)

    Kish, Jules G. (Inventor); Isabelle, Charles (Inventor)

    1994-01-01

    The topology of parallel axis gears, such as spur and helical gears is modified to produce quieter and more smoothly operating gear sets with more uniform load distribution. A finite element analysis of the gear in its operating mode is made to produce a plot of radial and tangential deflections of the pinion and gear tooth surfaces which will occur when the gears are loaded during operation. The resultant plot is then inverted to produce a plot, or set of coordinates, which will define the path of travel of the gear tooth grinding wheel, which path is a mirror image of the plot of the finite element analysis. The resulting gears, when subjected to operating loads, will thus be deflected tangentially and radially to their optimum operating, or theoretical true involute, positions so as to produce quieter, smoother, and more evenly loaded gear trains.

  3. Mars Surveyor Project Landing Site Activities

    NASA Technical Reports Server (NTRS)

    Gulick, Virginia C.; Briggs, Geoffrey; Saunders, R. Stephen; Gilmore, Martha; Soderblom, Larry

    1999-01-01

    The Mars Surveyor Program --now a cooperative program led by NASA and CNES along with other international partners -- is underway. It has the primary science objective of furthering our understanding of the biological potential and possible biological history of Mars and has the complementary objective of improving our understanding of martian climate evolution and planetary history The missions will develop technology and acquire data necessary for eventual human Exploration. Launches of orbiters, landers and rovers will take place in 2001 and in 2003; in 2005 a complete system will be launched capable of returning samples to Earth by 2008. A key aspect of the program is the selection of landing sites. This abstract 1) reports on the status of the landing site selection process that begins with the 2001 lander mission and 2) outlines be opportunities for the Mars community to provide input into the landing site selection process.

  4. Mars Surveyor Project Landing Site Activities

    NASA Technical Reports Server (NTRS)

    Gulick, V. C.; Briggs, Geoffrey; Saunders, R. Stephen; Gilmore, Martha; Soderblom, Larry

    1999-01-01

    The Mars Surveyor Program -- now a cooperative program led by NASA and CNES along with other international partners -- is underway. It has the primary science objective of furthering our understanding of the biological potential and possible biological history of Mars and has the complementary objective of improving our understanding of martian climate evolution and planetary history. The missions will develop technology and acquire data necessary for eventual human exploration. Launches of orbiters, landers and rovers will take place in 2001 and in 2003; in 2005 a complete system will be launched capable of returning samples to Earth by 2008. A key aspect of the program is the selection of landing sites. This abstract 1) reports on the status of the landing site selection process that begins with the 2001 lander mission and 2) outlines the opportunities for the Mars community to provide input into the landing site selection process.

  5. Modular gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  6. Anti-backlash gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  7. Offset Compound Gear Drive

    NASA Technical Reports Server (NTRS)

    Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

    2010-01-01

    The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths. Low-speed operation is accomplished in two meshes. For the purpose of illustrating the low-speed output operation, the following example pitch diameters are given. A 5.0 pitch diameter (PD) input gear to 7.50 PD (internal tooth) intermediate gear (0.667 reduction mesh), and a 7.50 PD (external tooth) intermediate gear to a 10.00 PD output gear (0.750 reduction mesh). Note that it is not required that the intermediate gears on the offset axis be of the same diameter. For this example, the resultant low-speed ratio is 2:1 (output speed = 0.500; product of stage one 0.667 reduction and stage two 0.750 stage reduction). The design is not restricted to the example pitch diameters, or output ratio. From the output gear, power is transmitted through a hollow drive shaft, which, in turn, drives a sprag during which time the main clutch is disengaged.

  8. Gear bearing drive

    NASA Technical Reports Server (NTRS)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  9. 34 CFR 694.22 - What other activities may all GEAR UP projects provide?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., for eligible students. (b) Conducting outreach activities to recruit priority students (identified in... eligible students. (d) Supporting the development or implementation of rigorous academic curricula, which... providing participating students access to rigorous core academic courses that reflect challenging...

  10. 34 CFR 694.22 - What other activities may all GEAR UP projects provide?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., for eligible students. (b) Conducting outreach activities to recruit priority students (identified in... eligible students. (d) Supporting the development or implementation of rigorous academic curricula, which... providing participating students access to rigorous core academic courses that reflect challenging...

  11. Pre-landing wrist muscle activity in hopping toads.

    PubMed

    Ekstrom, Laura J; Gillis, Gary B

    2015-08-01

    Coordinated landing requires preparation. Muscles in the limbs important for decelerating the body should be activated prior to impact so that joints may be stiffened and limbs stabilized during landing. Moreover, because landings vary in impact force and timing, muscle recruitment patterns should be modulated accordingly. In toads, which land using their forelimbs, previous work has demonstrated such modulation in muscles acting at the elbow, but not at the shoulder. In this study, we used electromyography and high-speed video to test the hypothesis that antagonistic muscles acting at the wrists of toads are activated in advance of impact, and that these activation patterns are tuned to the timing and force of impact. We recorded from two wrist extensors: extensor carpi ulnaris (ECU) and extensor digitorum communis longus (EDCL), and two wrist flexors: flexor carpi ulnaris (FCU) and palmaris longus (PL). Each muscle was recorded in 4-5 animals (≥15 hops per animal). In all muscles, activation intensity was consistently greatest shortly before impact, suggesting the importance of these muscles during landing. Pre-landing recruitment intensity regularly increased with aerial phase duration (i.e. hop distance) in all muscles except PL. In addition, onset timing in both wrist flexors was also modulated with hop distance, with later onset times being associated with longer hops. Thus, activation patterns in major flexors and extensors of the wrist are tuned to hop distance with respect to recruitment intensity, onset timing or both.

  12. Modelling polymer draft gears

    NASA Astrophysics Data System (ADS)

    Wu, Qing; Yang, Xiangjian; Cole, Colin; Luo, Shihui

    2016-09-01

    This paper developed a new and simple approach to model polymer draft gears. Two types of polymer draft gears were modelled and compared with experimental data. Impact characteristics, in-train characteristics and frequency responses of these polymer draft gears were studied and compared with those of a friction draft gear. The impact simulations show that polymer draft gears can withstand higher impact speeds than the friction draft gear. Longitudinal train dynamics simulations show that polymer draft gears have significantly longer deflections than friction draft gears in normal train operations. The maximum draft gear working velocities are lower than 0.2 m/s, which are significantly lower than the impact velocities during shunting operations. Draft gears' in-train characteristics are similar to their static characteristics but are very different from their impact characteristics; this conclusion has also been reached from frequency response simulations. An analysis of gangway bridge plate failures was also conducted and it was found that they were caused by coupler angling behaviour and long draft gear deflections.

  13. Phase-Oriented Gear Systems

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    2007-01-01

    Phase-oriented gear systems are differential planetary transmissions in which each planet gear has two sets of unequal numbers of teeth indexed at prescribed relative angles (phases). The figure illustrates an application of the phase-oriented gearing concept to a relatively simple speed-reducing differential planetary transmission that includes a sun gear, an idler gear, three identical planet gears, a ground internal ring gear, and an output internal ring gear. Typically, the ground internal ring gear and output internal ring gear have different numbers of teeth, giving rise to a progressive and periodic phase shift between the corresponding pairs of teeth engaged by each successive planet gear. To accommodate this phase shift, it is necessary to introduce a compensating phase shift between the ground-gear-engaging and output-gearengaging sections of each planet gear. This is done by individually orienting each planet gear

  14. 14 CFR 25.487 - Rebound landing condition.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .... (a) The landing gear and its supporting structure must be investigated for the loads occurring during rebound of the airplane from the landing surface. (b) With the landing gear fully extended and not in contact with the ground, a load factor of 20.0 must act on the unsprung weights of the landing gear....

  15. 14 CFR 25.487 - Rebound landing condition.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .... (a) The landing gear and its supporting structure must be investigated for the loads occurring during rebound of the airplane from the landing surface. (b) With the landing gear fully extended and not in contact with the ground, a load factor of 20.0 must act on the unsprung weights of the landing gear....

  16. 14 CFR 25.487 - Rebound landing condition.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .... (a) The landing gear and its supporting structure must be investigated for the loads occurring during rebound of the airplane from the landing surface. (b) With the landing gear fully extended and not in contact with the ground, a load factor of 20.0 must act on the unsprung weights of the landing gear....

  17. 14 CFR 25.487 - Rebound landing condition.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... (a) The landing gear and its supporting structure must be investigated for the loads occurring during rebound of the airplane from the landing surface. (b) With the landing gear fully extended and not in contact with the ground, a load factor of 20.0 must act on the unsprung weights of the landing gear....

  18. Variable gearing during locomotion in the human musculoskeletal system.

    PubMed

    Carrier, D R; Heglund, N C; Earls, K D

    1994-07-29

    Human feet and toes provide a mechanism for changing the gear ratio of the ankle extensor muscles during a running step. A variable gear ratio could enhance muscle performance during constant-speed running by applying a more effective prestretch during landing, while maintaining the muscles near the high-efficiency or high-power portion of the force-velocity curve during takeoff. Furthermore, during acceleration, variable gearing may allow muscle contractile properties to remain optimized despite rapid changes in running speed. Forceplate and kinematic analyses of running steps show low gear ratios at touchdown that increase throughout the contact phase. PMID:8036513

  19. The Potential Radiative Forcing of Global Land Use and Land Cover Change Activities

    NASA Astrophysics Data System (ADS)

    Ward, D. S.; Mahowald, N. M.; Kloster, S.

    2014-12-01

    Given the expected increase in pressure on land resources over the next century, there is a need to understand the total impacts of activities associated with land use and land cover change (LULCC). Here we quantify these impacts using the radiative forcing metric, including forcings from changes in long-lived greenhouse gases, tropospheric ozone, aerosol effects, and land surface albedo. We estimate radiative forcings from the different agents for historical LULCC and for six future projections using simulations from the National Center for Atmospheric Research Community Land Model and Community Atmosphere Models and additional offline analyses. When all forcing agents are considered together we show that 45% (+30%, -20%) of the present-day (2010) anthropogenic radiative forcing can be attributed to LULCC. Changes in the emission of non-CO2 greenhouse gases and aerosols from LULCC enhance the total LULCC radiative forcing by a factor of 2 to 3 with respect to the forcing from CO2 alone. In contrast, the non-CO2 forcings from fossil fuel burning are roughly neutral, due largely to the negative (cooling) impact of aerosols from these sources. We partition the global LULCC radiative forcing into three major sources: direct modification of land cover (e.g. deforestation), agricultural activities, and fire regime changes. Contributions from deforestation and agriculture are roughly equal in the present day, while changes to wildfire activity impose a small negative forcing globally. In 2100, deforestation activities comprise the majority of the LULCC radiative forcing for all projections except one (Representative Concentration Pathway (RCP) 4.5). This suggests that realistic scenarios of future forest area change are essential for projecting the contribution of LULCC to climate change. However, the commonly used RCP land cover change projections all include decreases in global deforestation rates over the next 85 years. To place an upper bound on the potential

  20. Detail of plate and gears on center pivot. From civilian ...

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

    Detail of plate and gears on center pivot. From civilian land. Looking north. - Naval Supply Annex Stockton, Daggett Road Bridge, Daggett Road traversing Burns Cut Off, Stockton, San Joaquin County, CA

  1. Gearing Up for Mountain Biking.

    ERIC Educational Resources Information Center

    Jahnke, Thomas; Hamson, Mike

    1999-01-01

    Examines the gear system of a mountain bike to discover any redundancy in the many gear settings available to the cyclist. Suggests a best strategy for changing up through the gears on a typical 21-gear system and an adjustment to the available gears that would result in a smoother change. (Author/ASK)

  2. Doing Mathematics with Bicycle Gear Ratios.

    ERIC Educational Resources Information Center

    Stump, Sheryl L.

    2000-01-01

    Describes an activity in which students examine bicycle chain-rings, cogs, and gear ratios as a means of exploring algebraic relationships, data collection, scatter plots, and lines of best fit. (KHR)

  3. 12. TRANSMISSION GEARING SHOWING RELATION TO SEGMENT GEAR ON WATERWHEEL ...

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

    12. TRANSMISSION GEARING SHOWING RELATION TO SEGMENT GEAR ON WATERWHEEL william E. Barrett, photographer, 1973 (copy negative) - Thomas Shepherd's Grist Mill, High Street Vicinity, Shepherdstown, Jefferson County, WV

  4. Liquid rocket engine turbopump gears

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Design and fabrication of gear drives for rocket engine turbopumps are described in the sequence encountered during the design process as follows: (1) selection of overall arrangement; (2) selection of gear type; (3) preliminary sizing; (4) lubrication system design; (5) detail tooth design; (6) selection of gear materials; and (7) gear fabrication and testing as it affects the design. The description is oriented towards the use of involute spur gears, although reference material for helical gears is also cited.

  5. Mining Claim Activity on Federal Land in the United States

    USGS Publications Warehouse

    Causey, J. Douglas

    2007-01-01

    Several statistical compilations of mining claim activity on Federal land derived from the Bureau of Land Management's LR2000 database have previously been published by the U.S Geological Survey (USGS). The work in the 1990s did not include Arkansas or Florida. None of the previous reports included Alaska because it is stored in a separate database (Alaska Land Information System) and is in a different format. This report includes data for all states for which there are Federal mining claim records, beginning in 1976 and continuing to the present. The intent is to update the spatial and statistical data associated with this report on an annual basis, beginning with 2005 data. The statistics compiled from the databases are counts of the number of active mining claims in a section of land each year from 1976 to the present for all states within the United States. Claim statistics are subset by lode and placer types, as well as a dataset summarizing all claims including mill site and tunnel site claims. One table presents data by case type, case status, and number of claims in a section. This report includes a spatial database for each state in which mining claims were recorded, except North Dakota, which only has had two claims. A field is present that allows the statistical data to be joined to the spatial databases so that spatial displays and analysis can be done by using appropriate geographic information system (GIS) software. The data show how mining claim activity has changed in intensity, space, and time. Variations can be examined on a state, as well as a national level. The data are tied to a section of land, approximately 640 acres, which allows it to be used at regional, as well as local scale. The data only pertain to Federal land and mineral estate that was open to mining claim location at the time the claims were staked.

  6. Remote sensing of environmental impact of land use activities

    NASA Technical Reports Server (NTRS)

    Paul, C. K.

    1977-01-01

    The capability to monitor land cover, associated in the past with aerial film cameras and radar systems, was discussed in regard to aircraft and spacecraft multispectral scanning sensors. A proposed thematic mapper with greater spectral and spatial resolutions for the fourth LANDSAT is expected to usher in new environmental monitoring capability. In addition, continuing improvements in image classification by supervised and unsupervised computer techniques are being operationally verified for discriminating environmental impacts of human activities on the land. The benefits of employing remote sensing for this discrimination was shown to far outweigh the incremental costs of converting to an aircraft-satellite multistage system.

  7. Partial tooth gear bearings

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  8. Land processes distributed active archive center product lifecycle plan

    USGS Publications Warehouse

    Daucsavage, John C.; Bennett, Stacie D.

    2014-01-01

    The U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center and the National Aeronautics and Space Administration (NASA) Earth Science Data System Program worked together to establish, develop, and operate the Land Processes (LP) Distributed Active Archive Center (DAAC) to provide stewardship for NASA’s land processes science data. These data are critical science assets that serve the land processes science community with potential value beyond any immediate research use, and therefore need to be accounted for and properly managed throughout their lifecycle. A fundamental LP DAAC objective is to enable permanent preservation of these data and information products. The LP DAAC accomplishes this by bridging data producers and permanent archival resources while providing intermediate archive services for data and information products.

  9. Design of Gear Drives With High Gear Ratio

    NASA Technical Reports Server (NTRS)

    Litvin, Faydor L.; Fuentes, Alfonso; Vecchiato, Daniele; Gonzalez-Perez, Ignacio

    2005-01-01

    A three part paper to describe the results of several gear drive types with a high gear ratio is presented. A single stage planetary gear train with double helical gears is described with methods to reduce transmission errors and improve load distribution by regulating backlash during assembly. A new arrangement for face gear is also described. This new mechanism can perform rotations between axes that are collinear and intersected. Finally the design and simulation of an isostatic planetary gear train is presented. Conditions that can lead to noise and vibration of the planetary gear drive are described.

  10. High-Ratio Gear Train

    NASA Technical Reports Server (NTRS)

    Lefever, A. E.

    1982-01-01

    Proposed arrangement of two connected planetary differentials results in gear ratio many times that obtainable in conventional series gear assembly of comparable size. Ratios of several thousand would present no special problems. Selection of many different ratios is available with substantially similar gear diameters. Very high gear ratios would be obtained from small mechanism.

  11. Gear assembly for automobile transmission

    SciTech Connect

    Ikemoto, K.; Tera Kura, Y.; Miyake, T.

    1986-03-25

    This patent describes a gear assembly including a pair of driving and driven gears permanently in meshing engagement with each other to provide a torque transmission therebetween. The driven gear is formed at one side thereof with a boss portion, and an additional gear axially slidable and rotatable on the boss portion of the driven gear and is permanently in meshing engagement with the driving gear to rotate at a gear ratio different from that of the driving and driven gears, additional gear is also resiliently in contact with a synchronizer mechanism assembled adjaecnt to the additional gear and having a spline piece fixed to the boss portion of the driven gear. The improvement wherein a toothed portion of the driven gear is formed at one end thereof with an annual stepped portion for provision of a predetermined annular gap between the additional gear and the one end face of the toothed portion of the driven gear. The resilient means is a waveshaped ring spring arranged in surrounding relationship with the boss portion of the driven gear and is engaged at its one end face with the additional gear and at its other end face with the spline piece of the synchronizer mechanism.

  12. Epicyclic gear speed change mechanism

    SciTech Connect

    Shimizu, Y.

    1987-02-24

    This patent describes a speed change pulley drive mechanism employing an epicyclic gear train with a ring gear, multiple planet gears and a sun gear, input and output members, and a clutch operable to either directly connect the input and output rotary members or indirectly connect the input and output members through the epicyclic gear train. The improvement described here comprises means supporting the sun gear for preventing rotational movement while permitting only limited radial movement and for relatively uniformly engaging the multiple planet gears.

  13. U.S. Geological Survey land remote sensing activities

    USGS Publications Warehouse

    Frederick, Doyle G.

    1983-01-01

    The U.S. Geological Survey (USGS) and the Department of the Interior (DOI) were among the earliest to recognize the potential applications of satellite land remote sensing for management of the country's land and water resources…not only as a user but also as a program participant responsible for final data processing, product generation, and data distribution. With guidance from Dr. William T. Pecora, who was the Survey's Director at that time and later Under Secretary of Interior, the Earth Resources Observation Systems (EROS) Program was established in 1966 as a focal point for these activities within the Department. Dr. Pecora was among the few who could envision a role for the Survey and the Department as active participants in programs yet to come--like the Landsat, Magsat, Seasat and, most recently, Shuttle Imaging Radar programs.

  14. Computing Stresses In Spur Gears

    NASA Technical Reports Server (NTRS)

    Oswald, F. B.; Lin, H. H.

    1995-01-01

    Dynamic Analysis of Spur Gear Transmissions (DANST) developed as easy-to-use program for static and dynamic analysis of spur-gear systems. Used for parametric studies to predict effects of operating speed, torque, stiffness, damping, inertia, and tooth profile on dynamic loads and tooth-bending stresses in spur gears. Performs geometric modeling and dynamic analysis for low- or high-contact-ratio spur gears. Simulates gear systems with contact ratios ranging from one to three. Written in FORTRAN 77.

  15. 50 CFR 648.91 - Monkfish regulated mesh areas and restrictions on gear and methods of fishing.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... restrictions on gear and methods of fishing. 648.91 Section 648.91 Wildlife and Fisheries FISHERY CONSERVATION... § 648.91 Monkfish regulated mesh areas and restrictions on gear and methods of fishing. All vessels fishing for, possessing or landing monkfish must comply with the following minimum mesh size, gear,...

  16. 50 CFR 622.188 - Required gear, authorized gear, and unauthorized gear.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE CARIBBEAN, GULF OF MEXICO..., sea bass pot, and spearfishing gear. (c) Unauthorized gear. All gear types other than those specified... unauthorized gear on board may not be transferred at sea, regardless of where such transfer takes place,...

  17. 50 CFR 622.188 - Required gear, authorized gear, and unauthorized gear.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE FISHERIES OF THE CARIBBEAN, GULF OF MEXICO..., sea bass pot, and spearfishing gear. (c) Unauthorized gear. All gear types other than those specified... unauthorized gear on board may not be transferred at sea, regardless of where such transfer takes place,...

  18. Planetary gear unit

    SciTech Connect

    Takahashi, S.

    1986-10-07

    This patent describes a planetary gear unit for the transmission of a motor vehicle, comprising: a first planetary gear unit which includes a pinion shaft, a planet pinion rotatably mounted on the pinion shaft, a sun gear engaging the planet pinion, and an arm member supporting the pinion shaft and having an extending portion extending to a point adjacent the sun gear; a thrust washer contacting the arm member, the thrust washer having radiating conduit means formed on a contacting surface thereof so as to communicate an inner circumference of the extending portion of the arm member with the pinion shaft, the pinion shaft having a conduit formed therein so as to communicate with the radiating conduit means with an inner surface of the planet pinion wherein the radiating conduit means further comprises uniform spaced bevel surfaces and grooves in communication with the bevel surfaces.

  19. Communication: Molecular gears.

    PubMed

    Burnell, E Elliott; de Lange, Cornelis A; Meerts, W Leo

    2016-09-01

    The (1)H nuclear magnetic resonance spectrum of hexamethylbenzene orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy. The spectrum contains over 350 000 lines with many overlapping transitions, from which four independent direct dipolar couplings are obtained. The rotations of the six methyl groups appear to be correlated due to mutual steric hindrance. Adjacent methyl groups show counter-rotating or geared motion. Hexamethylbenzene thus behaves as a molecular hexagonal gear. PMID:27608981

  20. Communication: Molecular gears

    NASA Astrophysics Data System (ADS)

    Burnell, E. Elliott; de Lange, Cornelis A.; Meerts, W. Leo

    2016-09-01

    The 1H nuclear magnetic resonance spectrum of hexamethylbenzene orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy. The spectrum contains over 350 000 lines with many overlapping transitions, from which four independent direct dipolar couplings are obtained. The rotations of the six methyl groups appear to be correlated due to mutual steric hindrance. Adjacent methyl groups show counter-rotating or geared motion. Hexamethylbenzene thus behaves as a molecular hexagonal gear.

  1. Langley Aircraft Landing Dynamics Facility

    NASA Technical Reports Server (NTRS)

    Davis, Pamela A.; Stubbs, Sandy M.; Tanner, John A.

    1987-01-01

    The Langley Research Center has recently upgraded the Landing Loads Track (LLT) to improve the capability of low-cost testing of conventional and advanced landing gear systems. The unique feature of the Langley Aircraft Landing Dynamics Facility (ALDF) is the ability to test aircraft landing gear systems on actual runway surfaces at operational ground speeds and loading conditions. A historical overview of the original LLT is given, followed by a detailed description of the new ALDF systems and operational capabilities.

  2. The Dilemma of Derelict Gear.

    PubMed

    Scheld, A M; Bilkovic, D M; Havens, K J

    2016-01-01

    Every year, millions of pots and traps are lost in crustacean fisheries around the world. Derelict fishing gear has been found to produce several harmful environmental and ecological effects, however socioeconomic consequences have been investigated less frequently. We analyze the economic effects of a substantial derelict pot removal program in the largest estuary of the United States, the Chesapeake Bay. By combining spatially resolved data on derelict pot removals with commercial blue crab (Callinectes sapidus) harvests and effort, we show that removing 34,408 derelict pots led to significant gains in gear efficiency and an additional 13,504 MT in harvest valued at US $21.3 million--a 27% increase above that which would have occurred without removals. Model results are extended to a global analysis where it is seen that US $831 million in landings could be recovered annually by removing less than 10% of the derelict pots and traps from major crustacean fisheries. An unfortunate common pool externality, the degradation of marine environments is detrimental not only to marine organisms and biota, but also to those individuals and communities whose livelihoods and culture depend on profitable and sustainable marine resource use. PMID:26790394

  3. The Dilemma of Derelict Gear

    PubMed Central

    Scheld, A. M.; Bilkovic, D. M.; Havens, K. J.

    2016-01-01

    Every year, millions of pots and traps are lost in crustacean fisheries around the world. Derelict fishing gear has been found to produce several harmful environmental and ecological effects, however socioeconomic consequences have been investigated less frequently. We analyze the economic effects of a substantial derelict pot removal program in the largest estuary of the United States, the Chesapeake Bay. By combining spatially resolved data on derelict pot removals with commercial blue crab (Callinectes sapidus) harvests and effort, we show that removing 34,408 derelict pots led to significant gains in gear efficiency and an additional 13,504 MT in harvest valued at US $21.3 million—a 27% increase above that which would have occurred without removals. Model results are extended to a global analysis where it is seen that US $831 million in landings could be recovered annually by removing less than 10% of the derelict pots and traps from major crustacean fisheries. An unfortunate common pool externality, the degradation of marine environments is detrimental not only to marine organisms and biota, but also to those individuals and communities whose livelihoods and culture depend on profitable and sustainable marine resource use. PMID:26790394

  4. Task Analysis of Shuttle Entry and Landing Activities

    NASA Technical Reports Server (NTRS)

    Holland, Albert W.; Vanderark, Stephen T.

    1993-01-01

    The Task Analysis of Shuttle Entry and Landing (E/L) Activities documents all tasks required to land the Orbiter following an STS mission. In addition to analysis of tasks performed, task conditions are described, including estimated time for completion, altitude, relative velocity, normal and lateral acceleration, location of controls operated or monitored, and level of g's experienced. This analysis precedes further investigations into potential effects of zero g on piloting capabilities for landing the Orbiter following long-duration missions. This includes, but is not limited to, researching the effects of extended duration missions on piloting capabilities. Four primary constraints of the analysis must be clarified: (1) the analysis depicts E/L in a static manner--the actual process is dynamic; (2) the task analysis was limited to a paper analysis, since it was not feasible to conduct research in the actual setting (i.e., observing or filming duration an actual E/L); (3) the tasks included are those required for E/L during nominal, daylight conditions; and (4) certain E/L tasks will vary according to the flying style of each commander.

  5. LIME KILN BUILDING, KILN BOTTOM SHOWING ROTATOR GEAR. (GEAR IS ...

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

    LIME KILN BUILDING, KILN BOTTOM SHOWING ROTATOR GEAR. (GEAR IS POINTED DOWN FOR PROPER ORIENTATION). - Solvay Process Company, Lime Kiln Building, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  6. Active microwave remote sensing of earth/land, chapter 2

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Geoscience applications of active microwave remote sensing systems are examined. Major application areas for the system include: (1) exploration of petroleum, mineral, and ground water resources, (2) mapping surface and structural features, (3) terrain analysis, both morphometric and genetic, (4) application in civil works, and (5) application in the areas of earthquake prediction and crustal movements. Although the success of radar surveys has not been widely publicized, they have been used as a prime reconnaissance data base for mineral exploration and land-use evaluation in areas where photography cannot be obtained.

  7. Gear type transmission apparatus

    SciTech Connect

    Sakamoto, K.; Shirai, E.; Moriyama, K.; Nagamatsu, H.

    1988-11-15

    This patent describes a gear type transmission apparatus comprising, a transmission case containing a gear train arrangement including gear trains and an output shaft to which an output of an engine is transmitted through the gear train arrangement and provided with an opening at an upper portion thereof, a cover member mounted on the upper portion of the transmission case to cover the opening, a holder member formed separately from the cover member and fixed on an under surface of the cover member to be positioned at the inside of a contacting face of the cover member provided for coming into contact with an upper end face of the transmission case, wherein the holder member is provided with a shift rod supporting portion disposed to be at least partially lower than the level of the contacting face of the cover member, and a shift rod supported by the shift rod supporting portion of the holder member to be movable in a direction along its axis at a position above the output shaft for causing the gear trains to be in operation to transmit the output selectively, and at least a part of one of the holder member and the shift rod is positioned to be higher than the lever of the contacting face.

  8. Gear crack propagation investigations

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Ballarini, Roberto

    1996-01-01

    Analytical and experimental studies were performed to investigate the effect of gear rim thickness on crack propagation life. The FRANC (FRacture ANalysis Code) computer program was used to simulate crack propagation. The FRANC program used principles of linear elastic fracture mechanics, finite element modeling, and a unique re-meshing scheme to determine crack tip stress distributions, estimate stress intensity factors, and model crack propagation. Various fatigue crack growth models were used to estimate crack propagation life based on the calculated stress intensity factors. Experimental tests were performed in a gear fatigue rig to validate predicted crack propagation results. Test gears were installed with special crack propagation gages in the tooth fillet region to measure bending fatigue crack growth. Good correlation between predicted and measured crack growth was achieved when the fatigue crack closure concept was introduced into the analysis. As the gear rim thickness decreased, the compressive cyclic stress in the gear tooth fillet region increased. This retarded crack growth and increased the number of crack propagation cycles to failure.

  9. Magnetic Gearing Versus Conventional Gearing in Actuators for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Puchhammer, Gregor

    2014-01-01

    Magnetic geared actuators (MGA) are designed to perform highly reliable, robust and precise motion on satellite platforms or aerospace vehicles. The design allows MGA to be used for various tasks in space applications. In contrast to conventional geared drives, the contact and lubrication free force transmitting elements lead to a considerable lifetime and range extension of drive systems. This paper describes the fundamentals of magnetic wobbling gears (MWG) and the deduced inherent characteristics, and compares conventional and magnetic gearing.

  10. 50 CFR 300.35 - Vessel and gear identification.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Vessel and gear identification. 300.35 Section 300.35 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.35 Vessel and gear identification. While a vessel is in...

  11. 50 CFR 300.130 - Vessel and gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Vessel and gear restrictions. 300.130 Section 300.130 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL... gear restrictions. (a) Factory vessels. Factory vessels are prohibited from operating in treaty...

  12. 50 CFR 300.130 - Vessel and gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 11 2012-10-01 2012-10-01 false Vessel and gear restrictions. 300.130 Section 300.130 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL... gear restrictions. (a) Factory vessels. Factory vessels are prohibited from operating in treaty...

  13. 50 CFR 300.130 - Vessel and gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 11 2014-10-01 2014-10-01 false Vessel and gear restrictions. 300.130 Section 300.130 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL... gear restrictions. (a) Factory vessels. Factory vessels are prohibited from operating in treaty...

  14. Kinematic precision of gear trains

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1983-01-01

    Kinematic precision is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic precision of gear trains is described. The method is based on the exact kinematic relations for the contact point motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic precision theory. Previously announced in STAR as N82-32733

  15. Kinematic precision of gear trains

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1982-01-01

    Kinematic precision is affected by errors which are the result of either intentional adjustments or accidental defects in manufacturing and assembly of gear trains. A method for the determination of kinematic precision of gear trains is described. The method is based on the exact kinematic relations for the contact point motions of the gear tooth surfaces under the influence of errors. An approximate method is also explained. Example applications of the general approximate methods are demonstrated for gear trains consisting of involute (spur and helical) gears, circular arc (Wildhaber-Novikov) gears, and spiral bevel gears. Gear noise measurements from a helicopter transmission are presented and discussed with relation to the kinematic precision theory.

  16. A superconducting magnetic gear

    NASA Astrophysics Data System (ADS)

    Campbell, A. M.

    2016-05-01

    A comparison is made between a magnetic gear using permanent magnets and superconductors. The objective is to see if there are any fundamental reasons why superconducting magnets should not provide higher power densities than permanent magnets. The gear is based on the variable permeability design of Attilah and Howe (2001 IEEE Trans. Magn. 37 2844-46) in which a ring of permanent magnets surrounding a ring of permeable pole pieces with a different spacing gives an internal field component at the beat frequency. Superconductors can provide much larger fields and forces but will saturate the pole pieces. However the gear mechanism still operates, but in a different way. The magnetisation of the pole pieces is now constant but rotates with angle at the beat frequency. The result is a cylindrical Halbach array which produces an internal field with the same symmetry as in the linear regime, but has an analytic solution. In this paper a typical gear system is analysed with finite elements using FlexPDE. It is shown that the gear can work well into the saturation regime and that the Halbach array gives a good approximation to the results. Replacing the permanent magnets with superconducting tapes can give large increases in torque density, and for something like a wind turbine a combined gear and generator is possible. However there are major practical problems. Perhaps the most fundamental is the large high frequency field which is inevitably present and which will cause AC losses. Also large magnetic fields are required, with all the practical problems of high field superconducting magnets in rotating machines. Nevertheless there are ways of mitigating these difficulties and it seems worthwhile to explore the possibilities of this technology further.

  17. Theory of gearing

    NASA Technical Reports Server (NTRS)

    Litvin, Faydor L.

    1989-01-01

    Basic mathematical problems on the theory of gearing are covered in this book, such as the necessary and sufficient conditions of envelope existence, relations between principal curvatures and directions for surfaces of mating gears. Also included are singularities of surfaces accompanied by undercutting the process of generation, the phenomena of envelope of lines of contact, and the principles for generation of conjugate surfaces. Special attention is given to the algorithms for computer aided simulation of meshing and tooth contact. This edition was complemented with the results of research recently performed by the author and his doctoral students. The book contains sample problems and also problems for the reader to solve.

  18. The Land Processes Distributed Active Archive Center (LP DAAC)

    USGS Publications Warehouse

    Golon, Danielle K.

    2016-10-03

    The Land Processes Distributed Active Archive Center (LP DAAC) operates as a partnership with the U.S. Geological Survey and is 1 of 12 DAACs within the National Aeronautics and Space Administration (NASA) Earth Observing System Data and Information System (EOSDIS). The LP DAAC ingests, archives, processes, and distributes NASA Earth science remote sensing data. These data are provided to the public at no charge. Data distributed by the LP DAAC provide information about Earth’s surface from daily to yearly intervals and at 15 to 5,600 meter spatial resolution. Data provided by the LP DAAC can be used to study changes in agriculture, vegetation, ecosystems, elevation, and much more. The LP DAAC provides several ways to access, process, and interact with these data. In addition, the LP DAAC is actively archiving new datasets to provide users with a variety of data to study the Earth.

  19. Medical Screening for Individuals Supporting Spacecraft Launch and Landing Activities in Remote Locations

    NASA Technical Reports Server (NTRS)

    Powers. W. Edward

    2010-01-01

    This viewgraph presentation reviews the medical screening process and spacecraft launch and landing mission activities for astronauts. The topics include: 1) Launch and Landing Mission Overview; 2) Available Resources; and 3) Medical Screening Process.

  20. Bacteria turn tiny gears

    SciTech Connect

    2009-01-01

    Swarms of bacteria turn two 380-micron long gears, opening the possibility of building hybrid biological machines at the microscopic scale. Read more at Wired: http://www.wired.com/wiredscience/2009/12/bacterial-micro-machine/#more-15684 or Scientific American: http://www.scientificamerican.com/article.cfm?id=brownian-motion-bacteria

  1. Electronic automatic gear transmission control apparatus

    SciTech Connect

    Koshizawa, T.

    1989-04-25

    This patent describes an electronic automatic gear transmission control apparatus having a shift schedule map for commanding an optimum gear position based on a vehicle speed signal and an accelerator opening signal, the electronic automatic gear transmission control apparatus comprising: first means for comparing a gear position commanded by the shift schedule map with a present gear position; second means for effecting a gear shift to a gear position which is one gear position higher than the present gear position and for restraining a gear shift to the commanded gear position for a prescribed period of time, if the commanded gear position requires an upshift to a gear position which is two or more gear positions higher than the present gear position as a result of the comparison performed by the first means; and third means for holding the gear position which is one gear position higher than the present gear position until an accelerator pedal is depressed again, when the accelerator opening signal indicates an idling position while the gear shift up to the gear position which is one gear position higher than the present gear position, is being effected by the second means.

  2. Displaceable Gear Torque Controlled Driver

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  3. The design of worm gear sets

    NASA Technical Reports Server (NTRS)

    Razzaghi, Andrea I.

    1987-01-01

    A method is presented for designing worm gear sets to meet torque multiplication requirements. First, the fundamentals of worm gear design are discussed, covering worm gear set nomenclature, kinematics and proportions, force analysis, and stress analysis. Then, a suggested design method is discussed, explaining how to take a worm gear set application, and specify a complete worm gear set design. The discussions are limited to cylindrical worm gear sets that have a 90 deg shaft angle between the worm and the mating gear.

  4. Generation Method Improves Spiral Bevel Gears

    NASA Technical Reports Server (NTRS)

    Litvin, Faydor L.; Tsung, Wei-Jiung; Coy, John J.; Heine, Charles

    1989-01-01

    Conjugate tooth surfaces reduce kinematic errors. Method for generation of spiral bevel gears provides conjugated gear-tooth surfaces and improved bearing contact. Conjugated surfaces preferable because maintain constant gear ratios during tooth-contact cycles. Changing gear ratios of nonconjugated surfaces give rise to kinematical errors in transfer of motion from driving gears to driven gears. Errors major sources of noise in power transmissions. Computer program developed to simulate cutting and meshing processes for pinions and gears to minimize kinematical errors.

  5. Planetary gear train for automatic transmission

    SciTech Connect

    Hiraiwa, K.

    1987-04-28

    A planetary gear train is described for an automatic transmission, the planetary gear train having gear ratios including a first forward gear ratio and a reverse, the planetary gear train comprising: an input shaft; a basic planetary gearing including a first rotary element which is to be held stationary when the first gear ratio is established and also when the reverse is established, and a second rotary element which is to serve as an output member of the basic planetary gearing; an output planetary gear set including a ring gear, a sun gear and a pinion carrier; change speed means for establishing any desired one of the gear ratios; a clutch means for establishing a connection between the other one of the ring gear and the sun gear of the output planetary gear set and the first rotary element of the basic planetary gearing during operation with the first gear ratio and also during operation with the reverse, and a brake means for anchoring the other one of the ring gear and the sun gear of the output planetary gear set during operation with the reverse; and an output shaft connected to the pinion carrier of the output planetary gear set.

  6. Flow-Field Investigation of Gear-Flap Interaction on a Gulfstream Aircraft Model

    NASA Technical Reports Server (NTRS)

    Yao, Chung-Sheng; Jenkins, Luther N.; Bartram, Scott M.; Harris, Jerome; Khorrami, Mehdi R.; Mace, W. Derry

    2014-01-01

    Off-surface flow measurements of a high-fidelity 18% scale Gulfstream aircraft model in landing configuration with the main landing gear deployed are presented. Particle Image Velocimetry (PIV) and Laser Velocimetry (LV) were used to measure instantaneous velocities in the immediate vicinity of the main landing gear and its wake and near the inboard tip of the flap. These measurements were made during the third entry of a series of tests conducted in the NASA Langley Research Center (LaRC) 14- by 22-Foot Subsonic Tunnel (14 x 22) to obtain a comprehensive set of aeroacoustic measurements consisting of both aerodynamic and acoustic data. The majority of the off-body measurements were obtained at a freestream Mach number of 0.2, angle of attack of 3 degrees, and flap deflection angle of 39 degrees with the landing gear on. A limited amount of data was acquired with the landing gear off. LV was used to measure the velocity field in two planes upstream of the landing gear and to measure two velocity profiles in the landing gear wake. Stereo and 2-D PIV were used to measure the velocity field over a region extending from upstream of the landing gear to downstream of the flap trailing edge. Using a special traverse system installed under the tunnel floor, the velocity field was measured at 92 locations to obtain a comprehensive picture of the pertinent flow features and characteristics. The results clearly show distinct structures in the wake that can be associated with specific components on the landing gear and give insight into how the wake is entrained by the vortex at the inboard tip of the flap.

  7. Scoring of precision spur gears

    SciTech Connect

    Budinski, K.G. )

    1994-09-01

    A group of manufacturing machines employed precision spur gears as the timing mechanism for machine operations. These machines had worked successfully for about ten years with little or no problems with gear wear or deterioration. When new machines were brought on line with recently made gears there were immediate problems with gear tooth scoring. A laboratory study was conducted to determine if metallurgical conditions were related to the gear scoring. Recent gears were made from a modification of the alloy used in early gears. The new alloy has been modified to make it more resistant to softening in coating operations. Reciprocating wear tests and galling tests were conducted to compare the tribological characteristics of the old and new gear steels. It was determined that the threshold galling stress of the gear steels was strongly dependent on the hardness. The reciprocating wear tests indicated that the wear resistance was affected by the volume fraction of hard phases in the steels. The recommended short-term solution was to alter the tempering procedure for the steel to keep Rockwell C hardness above 60; the long-term solution was to change the gear material and lubrication.

  8. Gear Performance Improved by Coating

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    2004-01-01

    Gears, bearings, and other mechanical elements transmit loads through contacting surfaces. Even if properly designed, manufactured, installed, and maintained, gears and bearings will eventually fail because of the fatigue of the working surfaces. Economical means for extending the fatigue lives of gears and bearings are highly desired, and coatings offer the opportunity to engineer surfaces to extend the fatigue lives of mechanical components. A tungsten-containing diamondlike-carbon coating exhibiting high hardness, low friction, and good toughness was evaluated for application to spur gears. Fatigue testing was done at the NASA Glenn Research Center on both uncoated and coated spur gears. The results showed that the coating extended the surface fatigue lives of the gears by a factor of about 5 relative to the uncoated gears. For the experiments, a lot of spur test gears made from AISI 9310 gear steel were case-carburized and ground to aerospace specifications. The geometries of the 28-tooth, 8-pitch gears were verified as meeting American Gear Manufacturing Association (AGMA) quality class 12. One-half of the gears were randomly selected for coating. The method of coating was selected to achieve desired adherence, toughness, hardness, and low-friction characteristics. First the gears to be coated were prepared by blasting (vapor honing) with Al2O3 particles and cleaning. Then, the gears were provided with a thin adhesion layer of elemental chromium followed by magnetron sputtering of the outer coating consisting of carbon (70 at.%), hydrogen (15 at.%), tungsten (12 at.%), and nickel (3 at.%) (atomic percent at the surface). In total, the coating thickness was about 2.5 to 3 microns. As compared with the steel substrate, the coated surface was harder by a factor of about 2 and had a smaller elastic modulus. All gears were tested using a 5-centistoke synthetic oil, a 10,000-rpm rotation speed, and a hertzian contact stress of at least 1.7 GPa (250 ksi). Tests were

  9. Gear Drive Testing

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Philadelphia Gear Corporation used two COSMIC computer programs; one dealing with shrink fit analysis and the other with rotor dynamics problems in computerized design and test work. The programs were used to verify existing in-house programs to insure design accuracy by checking its company-developed computer methods against procedures developed by other organizations. Its specialty is in custom units for unique applications, such as Coast Guard ice breaking ships, steel mill drives, coal crusher, sewage treatment equipment and electricity.

  10. Tool Gear Documentation

    SciTech Connect

    May, J; Gyllenhaal, J

    2002-04-03

    Tool Gear is designed to allow tool developers to insert instrumentation code into target programs using the DPCL library. This code can gather data and send it back to the Client for display or analysis. Tools can use the Tool Gear client without using the DPCL Collector. Any collector using the right protocols can send data to the Client for display and analysis. However, this document will focus on how to gather data with the DPCL Collector. There are three parts to the task of using Tool Gear to gather data through DPCL: (1) Write the instrumentation code that will be loaded and run in the target program. The code should be in the form of one or more functions, which can pass data structures back to the Client by way of DPCL. The collections of functions is compiled into a library, as described in this report. (2) Write the code that tells the DPCL Collector about the instrumentation and how to forward data back to the Client. (3) Extend the client to accept data from the Collector and display it in a useful way. The rest of this report describes how to carry out each of these steps.

  11. 46 CFR 28.885 - Cargo gear.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo gear. 28.885 Section 28.885 Shipping COAST GUARD... Aleutian Trade Act Vessels § 28.885 Cargo gear. (a) The safe working load (SWL) for the assembled gear... the load the gear is approved to lift, excluding the weight of the gear itself. (b) All wire...

  12. 46 CFR 28.885 - Cargo gear.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Cargo gear. 28.885 Section 28.885 Shipping COAST GUARD... Aleutian Trade Act Vessels § 28.885 Cargo gear. (a) The safe working load (SWL) for the assembled gear... the load the gear is approved to lift, excluding the weight of the gear itself. (b) All wire...

  13. 46 CFR 28.885 - Cargo gear.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Cargo gear. 28.885 Section 28.885 Shipping COAST GUARD... Aleutian Trade Act Vessels § 28.885 Cargo gear. (a) The safe working load (SWL) for the assembled gear... the load the gear is approved to lift, excluding the weight of the gear itself. (b) All wire...

  14. 46 CFR 28.885 - Cargo gear.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Cargo gear. 28.885 Section 28.885 Shipping COAST GUARD... Aleutian Trade Act Vessels § 28.885 Cargo gear. (a) The safe working load (SWL) for the assembled gear... the load the gear is approved to lift, excluding the weight of the gear itself. (b) All wire...

  15. Independent Orbiter Assessment (IOA): Analysis of the landing/deceleration subsystem

    NASA Technical Reports Server (NTRS)

    Compton, J. M.; Beaird, H. G.; Weissinger, W. D.

    1987-01-01

    The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Landing/Deceleration Subsystem hardware. The Landing/Deceleration Subsystem is utilized to allow the Orbiter to perform a safe landing, allowing for landing-gear deploy activities, steering and braking control throughout the landing rollout to wheel-stop, and to allow for ground-handling capability during the ground-processing phase of the flight cycle. Specifically, the Landing/Deceleration hardware consists of the following components: Nose Landing Gear (NLG); Main Landing Gear (MLG); Brake and Antiskid (B and AS) Electrical Power Distribution and Controls (EPD and C); Nose Wheel Steering (NWS); and Hydraulics Actuators. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Due to the lack of redundancy in the Landing/Deceleration Subsystems there is a high number of critical items.

  16. Muscle gearing during isotonic and isokinetic movements in the ankle plantarflexors.

    PubMed

    Randhawa, Avleen; Jackman, Meghan E; Wakeling, James M

    2013-02-01

    Muscle-tendon gearing is the ratio of the muscle-tendon unit velocity to the fascicle velocity and can be expressed as the product of the gearing within the muscle belly and the gearing due to tendon stretch. Previous studies have shown that gearing is variable and increases at higher velocities. Changes in the muscle activation levels and force development have been suggested to affect tendon gearing and thus muscle-tendon unit gearing. However, the role of belly gearing as a part of muscle-tendon gearing and its associations with structural aspects of muscle and thus movement performance are important facets that need to be studied. The two gastrocnemii of twenty young adults were tested during isokinetic and isotonic contractions on an ankle dynamometer. Ultrasound images of both muscles were collected during contractions and were later digitised. Gearing was also predicted using a 2-dimensional panel model of these muscles. The results from experimental and models tests showed increases in gearing with greater torque levels at slower contraction velocities. However, in the isotonic models there was a substantial increase in gearing at faster contraction velocities. The level of muscle-tendon unit gearing is largely determined by the belly gearing, but its variability is driven by changes in tendon gearing that in turn is a factor of the muscle activation and coordination. The belly thickness of the medial gastrocnemius decreased during contractions, but increased for the lateral gastrocnemius. It is likely that changes to the belly shape and 3-dimensional structure are important to the gearing of the muscle.

  17. Worm Gear With Hydrostatic Engagement

    NASA Technical Reports Server (NTRS)

    Chaiko, Lev I.

    1994-01-01

    In proposed worm-gear transmission, oil pumped at high pressure through meshes between teeth of gear and worm coil. Pressure in oil separates meshing surfaces slightly, and oil reduces friction between surfaces. Conceived for use in drive train between gas-turbine engine and rotor of helicopter. Useful in other applications in which weight critical. Test apparatus simulates and measures some loading conditions of proposed worm gear with hydrostatic engagement.

  18. Gears Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Globus, Al; Deardorff, Glenn

    2005-01-01

    Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by

  19. Technology Innovation of Power Transmission Gearing in Aviation

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.

    2009-01-01

    An overview of rotary wing evolution and innovations over the last 20 years was presented. This overview is provided from a drive system perspective. Examples of technology innovations that have changed and advanced drive systems of rotary wing vehicles will be provided. These innovations include full 6-axis CNC gear manufacture, face gear development to aerospace standards, health and usage monitoring, and gear geometry and bearing improvements. Also, an overview of current state-of-the-art activities being conducted at NASA Glenn is presented with a short look to fixed and rotary wing aircraft and systems needed for the future.

  20. High Pressure Angle Gears: Comparison to Typical Gear Designs

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Zabrajsek, Andrew J.

    2010-01-01

    A preliminary study has been completed to determine the feasibility of using high-pressure angle gears in aeronautic and space applications. Tests were conducted in the NASA Glenn Research Center (GRC) Spur Gear Test Facility at speeds up to 10,000 rpm and 73 N*m (648 in.*lb) for 3.18, 2.12, and 1.59 module gears (8, 12, and 16 diametral pitch gears), all designed to operate in the same test facility. The 3.18 module (8-diametral pitch), 28 tooth, 20deg pressure angle gears are the GRC baseline test specimen. Also, 2.12 module (12-diametral pitch), 42 tooth, 25deg pressure angle gears were tested. Finally 1.59 module (16-diametral pitch), 56 tooth, 35deg pressure angle gears were tested. The high-pressure angle gears were the most efficient when operated in the high-speed aerospace mode (10,000 rpm, lubricated with a synthetic turbine engine oil), and produced the lowest wear rates when tested with a perfluoroether-based grease. The grease tests were conducted at 150 rpm and 71 N*m (630 in.*lb).

  1. Double Helical Gear Performance Results in High Speed Gear Trains

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

    2010-01-01

    The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

  2. Double Helical Gear Performance Results in High Speed Gear Trains

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

    2009-01-01

    The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

  3. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be.../submersibles. (b) American Samoa coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for coral reef ecosystem MUS in the management area is prohibited. (c) Existing...

  4. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may... vehicles/submersibles. (b) Mariana coral reef ecosystem MUS may not be taken by means of poisons... subpart who is established to be fishing for Mariana coral reef ecosystem MUS in the management area...

  5. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken.../submersibles. (b) Hawaii coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for Hawaii coral reef ecosystem MUS in the Hawaii management area is prohibited....

  6. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken.../submersibles. (b) Hawaii coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for Hawaii coral reef ecosystem MUS in the Hawaii management area is prohibited....

  7. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be.../submersibles. (b) American Samoa coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for coral reef ecosystem MUS in the management area is prohibited. (c) Existing...

  8. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may... vehicles/submersibles. (b) Mariana coral reef ecosystem MUS may not be taken by means of poisons... subpart who is established to be fishing for Mariana coral reef ecosystem MUS in the management area...

  9. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be.../submersibles. (b) American Samoa coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for coral reef ecosystem MUS in the management area is prohibited. (c) Existing...

  10. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken.../submersibles. (b) Hawaii coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for Hawaii coral reef ecosystem MUS in the Hawaii management area is prohibited....

  11. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may... vehicles/submersibles. (b) Mariana coral reef ecosystem MUS may not be taken by means of poisons... subpart who is established to be fishing for Mariana coral reef ecosystem MUS in the management area...

  12. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be.../submersibles. (b) American Samoa coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for coral reef ecosystem MUS in the management area is prohibited. (c) Existing...

  13. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may... vehicles/submersibles. (b) Mariana coral reef ecosystem MUS may not be taken by means of poisons... subpart who is established to be fishing for Mariana coral reef ecosystem MUS in the management area...

  14. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken.../submersibles. (b) Hawaii coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for Hawaii coral reef ecosystem MUS in the Hawaii management area is prohibited....

  15. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Island Area Fisheries § 665.627 Allowable gear and gear restrictions. (a) Coral reef ecosystem MUS may be...) Hand net/dip net; (5) Hoop net for Kona crab; (6) Throw net; (7) Barrier net; (8) Surround/purse net....) in the U.S. EEZ waters around Howland Island, Baker Island, Jarvis Island, Wake Island, Kingman...

  16. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Island Area Fisheries § 665.627 Allowable gear and gear restrictions. (a) Coral reef ecosystem MUS may be...) Hand net/dip net; (5) Hoop net for Kona crab; (6) Throw net; (7) Barrier net; (8) Surround/purse net....) in the U.S. EEZ waters around Howland Island, Baker Island, Jarvis Island, Wake Island, Kingman...

  17. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Island Area Fisheries § 665.627 Allowable gear and gear restrictions. (a) Coral reef ecosystem MUS may be...) Hand net/dip net; (5) Hoop net for Kona crab; (6) Throw net; (7) Barrier net; (8) Surround/purse net....) in the U.S. EEZ waters around Howland Island, Baker Island, Jarvis Island, Wake Island, Kingman...

  18. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Island Area Fisheries § 665.627 Allowable gear and gear restrictions. (a) Coral reef ecosystem MUS may be...) Hand net/dip net; (5) Hoop net for Kona crab; (6) Throw net; (7) Barrier net; (8) Surround/purse net....) in the U.S. EEZ waters around Howland Island, Baker Island, Jarvis Island, Wake Island, Kingman...

  19. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Island Area Fisheries § 665.627 Allowable gear and gear restrictions. (a) Coral reef ecosystem MUS may be...) Hand net/dip net; (5) Hoop net for Kona crab; (6) Throw net; (7) Barrier net; (8) Surround/purse net....) in the U.S. EEZ waters around Howland Island, Baker Island, Jarvis Island, Wake Island, Kingman...

  20. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be.../submersibles. (b) American Samoa coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for coral reef ecosystem MUS in the management area is prohibited. (c) Existing...

  1. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may... vehicles/submersibles. (b) Mariana coral reef ecosystem MUS may not be taken by means of poisons... subpart who is established to be fishing for Mariana coral reef ecosystem MUS in the management area...

  2. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken.../submersibles. (b) Hawaii coral reef ecosystem MUS may not be taken by means of poisons, explosives, or... established to be fishing for Hawaii coral reef ecosystem MUS in the Hawaii management area is prohibited....

  3. Precise low cost chain gears for heliostats

    NASA Astrophysics Data System (ADS)

    Liedke, Phillip; Lewandowski, Arkadiusz; Pfahl, Andreas; Hölle, Erwin

    2016-05-01

    This work investigates the potential of chain gears as precise and low cost driving systems for rim drive heliostats. After explaining chain gear basics the polygon effect and chain lengthening are investigated. The polygon effect could be measured by a heliostat with chain rim gear and the chain lengthening with an accordant test set up. Two gear stages are scope of this work: a rim gear and an intermediate gear. Dimensioning, pretensioning and designing for both stages are explained.

  4. Planetary gear train for automatic transmission

    SciTech Connect

    Hiraiwa, K.

    1987-03-31

    A planetary gear train is described comprising: a first planetary gear set having rotary elements including a first sun gear, a first ring gear and a first pinion carrier rotatably supporting a plurality of first pinions meshing with the first sun gear and the first ring gear; a second planetary gear set having rotary elements including a second sun gear, a second ring gear and a second pinion carrier rotatably supporting a plurality of second pinions meshing with the second sun gear and the second ring gear; an input shaft drivingly-connected with the first ring gear; an output shaft; first drive connection establishing means for connecting the second ring gear with the output shaft; the first drive connection establishing means comprising: a third planetary gear set including a third sun gear constantly connected with the second ring gear, a third ring gear, and a third pinion carrier constantly connected with the output shaft. The third pinion carrier rotatably supports third pinions meshing with the third sun and ring gears.

  5. Materials for helicopter gears

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Some of the power train transmission gears in helicopter drive systems can become critical components as performance requirements are increased; accordingly, increasing attention must be paid to new alloys in order to obtain required performance reliability and survivability. Candidate advanced alloys, with improved high temperature properties, while increasing the resistance to scoring and scuffing, tend to have lower ductility and fracture toughness. An attempt is made to identify design materials, and process problems and requirements. In addition, it is recommended that the characterization of candidate steels be accelerated; preliminary investigation indicates that new alloys may provide improved capability against surface distress.

  6. Selected physiological and psychological responses to live-fire drills in different configurations of firefighting gear.

    PubMed

    Smith, D L; Petruzzello, S J

    1998-08-01

    The purpose of this study was to examine selected physiological and psychological responses to strenuous live-fire drills in different configurations of protective firefighting gear. Career firefighters (n = 10) performed three sets of firefighting drills in a training structure that contained live fires in two different configurations of firefighting gear. On separate days subjects wore: (a) the NFPA 1500 (1987) standard configuration, and (b) a hip-boot configuration of the firefighting gear. Physiological and psychological measurements were recorded pre-activity and at the end of each trial. Repeated measures ANOVA revealed a strong trend for performance time to be greater in the 1500 gear than in the hip-boot gear. There was a significant Time x Gear interaction for tympanic membrane temperature, with temperature being greater in the 1500 gear. Perceptions of effort and thermal sensations were also greater in the 1500 gear than in the hip-boot configuration of the gear. There was little difference in mean performance on cognitive function measures between the two gear configurations, but there was greater variability in performance in the 1500 gear. These data suggest that performing strenuous firefighting drills in the current NFPA 1500 standard configuration results in longer performance time, greater thermal strain, and greater perception of effort and thermal sensation.

  7. Torque-Splitting Gear Drive

    NASA Technical Reports Server (NTRS)

    Kish, J.

    1991-01-01

    Geared drive train transmits torque from input shaft in equal parts along two paths in parallel, then combines torques in single output shaft. Scheme reduces load on teeth of meshing gears while furnishing redundancy to protect against failures. Such splitting and recombination of torques common in design of turbine engines.

  8. Reliability model for planetary gear

    NASA Technical Reports Server (NTRS)

    Savage, M.; Paridon, C. A.; Coy, J. J.

    1982-01-01

    A reliability model is presented for planetary gear trains in which the ring gear is fixed, the Sun gear is the input, and the planet arm is the output. The input and output shafts are coaxial and the input and output torques are assumed to be coaxial with these shafts. Thrust and side loading are neglected. This type of gear train is commonly used in main rotor transmissions for helicopters and in other applications which require high reductions in speed. The reliability model is based on the Weibull distribution of the individual reliabilities of the transmission components. The transmission's basic dynamic capacity is defined as the input torque which may be applied for one million input rotations of the Sun gear. Load and life are related by a power law. The load life exponent and basic dynamic capacity are developed as functions of the component capacities.

  9. Thermal deformation of helical gears

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Fei, Ye-tai; Liu, Shan-lin

    2010-08-01

    The analytical equation for the thermal field of a helical gear under normal working condition in a stable thermal field is established using mathematical physics, and the thermal deformation of the gear can be computed using this equation. The variations of gear geometric parameters, such as radial dimension, tooth depth, spiral angle, pressure angle, flank clearance and etc., are investigated with respect to the temperature change. According to the analytical and computational results obtained using the equation, the thermal deformation of the gear is strongly dependent on the choice of parameters, which is also confirmed using simulation software (COMSOL Multiphysic software). This is significant for the improvement of the rotation precision and working efficiency of screw gears.

  10. Health Impact Assessment, Physical Activity and Federal Lands Trail Policy

    PubMed Central

    Davis, Sally M.; Cruz, Theresa H.; Kozoll, Richard L.

    2016-01-01

    Objectives The objectives of this paper are to describe the application of Health Impact Assessment (HIA) to inform trail decisions affecting a rural, under-resourced community and propose the routine integration of HIAs to enhance NEPA environmental assessments and environmental impact statements for trail decisions on federal lands. Methods Screening, scoping, assessment, recommendations, reporting, monitoring and evaluation are being used to examine the health impact of trail location and design. Results HIA recommendations are being integrated into the public lands National Environmental Protection Act process for planning access to a new segment of the Continental Divide National Scenic Trail. Potential users from a nearby rural New Mexico community and a region of almost one million may benefit from this HIA-informed planning. Conclusions HIA can be integrated into the policy and decision-making process for trails on public lands. PMID:27213163

  11. Improved Gear Shapes for Face Worm Gear Drives

    NASA Technical Reports Server (NTRS)

    Litvin, Faydor L.; Nava, Alessandro; Fan, Qi; Fuentes, Alfonso

    2005-01-01

    Shapes different from the traditional ones have been proposed for face worm gears and for conical and cylindrical worms that mesh with them. The proposed shapes are based on the concept of generating a face worm gear surface by use of a tilted head cutter instead of by the traditional use of a hob. (As used here, head cutter is also meant to signify, alternatively, a head grinding tool.) The gear-surface-generation equipment would be similar to that used for generation of spiral bevel and hypoid gears. In comparison with the corresponding traditional hob, a tilted head cutter according to the proposal would be larger, could be fabricated with greater precision, and would enable the generation of gear surfaces with greater precision and greater productivity. A face worm gear would be generated (see figure) by use of a tilted head cutter, the blades or grinding surfaces of which would have straight-line profiles. The tilt of the head cutter would prevent interference with teeth adjacent to the groove being cut or ground. A worm to mesh with the face worm gear would be generated by use of a tilted head cutter mounted on the cradle of a generating machine. The blades or grinding surfaces of the head cutter would have a parabolic profile and would deviate from the straight-line profiles of the head cutter for the face worm gear. The shortest distance between the worm and the cradle would follow a parabolic function during the cycle of meshing in the generating process to provide a parabolic function of transmission errors to the gear drive. The small mismatch between the profiles of the face-worm-gear and worm head cutters would make it possible to localize the bearing contact in the worm gear drive. The parabolic function of transmission errors could absorb discontinuous linear functions of transmission errors caused by errors of alignment; this could afford a significant benefit, in that such errors are main sources of noise and vibration in gear drives. The main

  12. Mining claim activity on federal land in the contiguous United States, 1976 through 2004

    USGS Publications Warehouse

    Causey, J. Douglas; Frank, David G.

    2006-01-01

    The data show how mining claim activity has changed in intensity, space, and time. Variations can be examined on a state, as well as a national level. The data are tied to a section of land, approximately 640 acres, which allows it to be used at regional, as well as local scale. It is restricted in that it only encompasses Federal land.

  13. 78 FR 73875 - Agency Information Collection Activities: Canadian Border Boat Landing Permit (CBP Form I-68)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-09

    ... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Canadian Border Boat Landing Permit (CBP Form I-68) AGENCY: U.S. Customs and Border Protection (CBP), Department of Homeland... requirement concerning the Canadian Border Boat Landing Permit (Form I-68). This request for comment is...

  14. Validation and Verification of Operational Land Analysis Activities at the Air Force Weather Agency

    NASA Technical Reports Server (NTRS)

    Shaw, Michael; Kumar, Sujay V.; Peters-Lidard, Christa D.; Cetola, Jeffrey

    2012-01-01

    The NASA developed Land Information System (LIS) is the Air Force Weather Agency's (AFWA) operational Land Data Assimilation System (LDAS) combining real time precipitation observations and analyses, global forecast model data, vegetation, terrain, and soil parameters with the community Noah land surface model, along with other hydrology module options, to generate profile analyses of global soil moisture, soil temperature, and other important land surface characteristics. (1) A range of satellite data products and surface observations used to generate the land analysis products (2) Global, 1/4 deg spatial resolution (3) Model analysis generated at 3 hours. AFWA recognizes the importance of operational benchmarking and uncertainty characterization for land surface modeling and is developing standard methods, software, and metrics to verify and/or validate LIS output products. To facilitate this and other needs for land analysis activities at AFWA, the Model Evaluation Toolkit (MET) -- a joint product of the National Center for Atmospheric Research Developmental Testbed Center (NCAR DTC), AFWA, and the user community -- and the Land surface Verification Toolkit (LVT), developed at the Goddard Space Flight Center (GSFC), have been adapted to operational benchmarking needs of AFWA's land characterization activities.

  15. Gear shift controller for automatic transmission

    SciTech Connect

    Nishikawa, M.; Sakai, S.; Sakurai, T.

    1987-01-20

    A gear shift controller is described for an automatic transmission having a gear shift, comprising: a hydraulic torque converter; a gear change group, having a plurality of gears, each gear providing a different transmission ratio for the transmission of power from the hydraulic torque converter to the output of the transmission, each of the gears comprising a gear train; a one-way clutch interposed in at least one of the gear trains; a plurality of clutch means operatively connected with the gear trains for actuating each of the gear trains selectively; a gear change determination circuit operatively connected with the clutch means to control the operation of each of the clutch means according to a predetermined gear shifting program for engaging a gear train selected by the program; a coasting detection circuit for detecting a car in the coasting state; a gear shift limiting circuit, operatively connected with the gear change determination circuit and with the coasting detection circuit. The circuit is for actuating only the gear train in which the one-way clutch is interposed immediately, regardless of the selected gear train and of the operation of the gear change determination circuit, when the coasting detection circuit has determined the car to be coasting; and an operation transfer control system including a brake operation detecting means and a mode selector switch means for transferring the operation of the gear shift limiting circuit. The operation transfer control system is adapted to stop, upon detection of one of the brake operation and a reset state of the mode selector switch, the operation of the gear shift limiting circuit and to place the plurality of clutch means under the control of the gear change determination circuit.

  16. 50 CFR 648.84 - Gear-marking requirements and gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Gear-marking requirements and gear... Management Measures for the NE Multispecies and Monkfish Fisheries § 648.84 Gear-marking requirements and gear restrictions. (a) Bottom-tending fixed gear, including, but not limited to, gillnets and...

  17. STS-49 Endeavour, OV-105, landing on concrete runway 22 at EAFB, California

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-49 Endeavour, Orbiter Vehicle (OV) 105, glides above concrete runway 22 at Edwards Air Force Base (EAFB), California, just before main landing gear (MLG) touchdown. Nose landing gear (NLG) is also deployed during the landing sequence. Landing occurred at 1:36:38 pm (Pacific Daylight Time (PDT)).

  18. Automated Inspection And Precise Grinding Of Gears

    NASA Technical Reports Server (NTRS)

    Frint, Harold; Glasow, Warren

    1995-01-01

    Method of precise grinding of spiral bevel gears involves automated inspection of gear-tooth surfaces followed by adjustments of machine-tool settings to minimize differences between actual and nominal surfaces. Similar to method described in "Computerized Inspection of Gear-Tooth Surfaces" (LEW-15736). Yields gears of higher quality, with significant reduction in manufacturing and inspection time.

  19. Functioning of reduction gears on airplane engines

    NASA Technical Reports Server (NTRS)

    Matteucci, Raffaelli

    1926-01-01

    In undertaking to analyze the functioning conditions of a reduction gear on an aviation engine, we will consider an ordinary twelve-cylinder V-engine. The reduction gear employed consists either of a pair of spur gears, one of which is integral with the engine shaft and the other with the propeller shaft, or of a planetary system of gears.

  20. 29 CFR 1918.54 - Rigging gear.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Rigging gear. 1918.54 Section 1918.54 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Vessel's Cargo Handling Gear § 1918.54 Rigging gear. (a... other alternate device shall be provided to allow trimming of the gear and to prevent employees...

  1. 29 CFR 1918.54 - Rigging gear.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Rigging gear. 1918.54 Section 1918.54 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Vessel's Cargo Handling Gear § 1918.54 Rigging gear. (a... other alternate device shall be provided to allow trimming of the gear and to prevent employees...

  2. 29 CFR 1918.54 - Rigging gear.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Rigging gear. 1918.54 Section 1918.54 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Vessel's Cargo Handling Gear § 1918.54 Rigging gear. (a... other alternate device shall be provided to allow trimming of the gear and to prevent employees...

  3. 29 CFR 1918.54 - Rigging gear.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Rigging gear. 1918.54 Section 1918.54 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Vessel's Cargo Handling Gear § 1918.54 Rigging gear. (a... other alternate device shall be provided to allow trimming of the gear and to prevent employees...

  4. 29 CFR 1918.54 - Rigging gear.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Rigging gear. 1918.54 Section 1918.54 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Vessel's Cargo Handling Gear § 1918.54 Rigging gear. (a... other alternate device shall be provided to allow trimming of the gear and to prevent employees...

  5. Computerized Inspection Of Gear-Tooth Surfaces

    NASA Technical Reports Server (NTRS)

    Handschuh, R. F.; Litvin, F. L.; Zhang, Y.; Kuan, C.

    1994-01-01

    Method of manufacturing gears with precisely shaped teeth involves computerized inspection of gear-tooth surfaces followed by adjustments of machine-tool settings to minimize deviations between real and theoretical versions of surfaces. Thus, iterated cycles of cutting gear teeth, inspection, and adjustments help increase and/or maintain precision of subsequently manufactured gears.

  6. Gearing up chromatin

    PubMed Central

    Mandemaker, Imke K; Vermeulen, Wim; Marteijn, Jurgen A

    2014-01-01

    During transcription, RNA polymerase may encounter DNA lesions, which causes stalling of transcription. To overcome the RNA polymerase blocking lesions, the transcribed strand is repaired by a dedicated repair mechanism, called transcription coupled nucleotide excision repair (TC-NER). After repair is completed, it is essential that transcription restarts. So far, the regulation and exact molecular mechanism of this transcriptional restart upon genotoxic damage has remained elusive. Recently, three different chromatin remodeling factors, HIRA, FACT, and Dot1L, were identified to stimulate transcription restart after DNA damage. These factors either incorporate new histones or establish specific chromatin marks that will gear up the chromatin to subsequently promote transcription recovery. This adds a new layer to the current model of chromatin remodeling necessary for repair and indicates that this specific form of transcription, i.e., the transcriptional restart upon DNA damage, needs specific chromatin remodeling events. PMID:24809693

  7. Bearing, gearing, and lubrication technology

    NASA Technical Reports Server (NTRS)

    Anderson, W. J.

    1978-01-01

    Results of selected NASA research programs on rolling-element and fluid-film bearings, gears, and elastohydrodynamic lubrication are reported. Advances in rolling-element bearing material technology, which have resulted in a significant improvement in fatigue life, and which make possible new applications for rolling bearings, are discussed. Research on whirl-resistant, fluid-film bearings, suitable for very high-speed applications, is discussed. An improved method for predicting gear pitting life is reported. An improved formula for calculating the thickness of elastohydrodynamic films (the existence of which help to define the operating regime of concentrated contact mechanisms such as bearings, gears, and cams) is described.

  8. Development in Geared Turbofan Aeroengine

    NASA Astrophysics Data System (ADS)

    Mohd Tobi, A. L.; Ismail, A. E.

    2016-05-01

    This paper looks into the implementation of epicyclic gear system to the aeroengine in order to increase the efficiency of the engine. The improvement made is in the direction of improving fuel consumption, reduction in pollutant gasses and perceived noise. Introduction of epicyclic gear system is capable to achieve bypass ratio of up to 15:1 with the benefits of weight and noise reduction. Radical new aircraft designs and engine installation are being studied to overcome some of the challenges associated with the future geared turbofan and open-rotor engine.

  9. Numerical Simulation Of Cutting Of Gear Teeth

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Huston, Ronald L.; Mavriplis, Dimitrios

    1994-01-01

    Shapes of gear teeth produced by gear cutters of specified shape simulated computationally, according to approach based on principles of differential geometry. Results of computer simulation displayed as computer graphics and/or used in analyses of design, manufacturing, and performance of gears. Applicable to both standard and non-standard gear-tooth forms. Accelerates and facilitates analysis of alternative designs of gears and cutters. Simulation extended to study generation of surfaces other than gears. Applied to cams, bearings, and surfaces of arbitrary rolling elements as well as to gears. Possible to develop analogous procedures for simulating manufacture of skin surfaces like automobile fenders, airfoils, and ship hulls.

  10. STS-82 Landing

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Space Shuttle orbiter Discovery touches down in darkness on Runway 15 of the KSC Shuttle Landing Facility, bringing to a close the 10-day STS-82 mission to service the Hubble Space Telescope (HST). Main gear touchdown was at 3:32:26 a.m. EST on February 21, 1997. It was the ninth nighttime landing in the history of the Shuttle program and the 35th landing at KSC. The first landing opportunity at KSC was waved off because of low clouds in the area. The seven-member crew performed a record- tying five back-to-back extravehicular activities (EVAs) or spacewalks to service the telescope, which has been in orbit for nearly seven years. Two new scientific instruments were installed, replacing two outdated instruments. Five spacewalks also were performed on the first servicing mission, STS-61, in December 1993. Only four spacewalks were scheduled for STS-82, but a fifth one was added during the flight to install several thermal blankets over some aging insulation covering three HST compartments containing key data processing, electronics and scientific instrument telemetry packages. Crew members are Mission Commander Kenneth D. Bowersox, Pilot Scott J. 'Doc' Horowitz, Payload Commander Mark C. Lee, and Mission Specialists Steven L. Smith, Gregory J. Harbaugh, Joseph R. 'Joe' Tanner and Steven A. Hawley. STS-82 was the 82nd Space Shuttle flight and the second mission of 1997.

  11. Dynamic hypoxic zones in Lake Erie compress fish habitat, altering vulnerability to fishing gears

    USGS Publications Warehouse

    Kraus, Richard T.; Knight, Carey T.; Farmer, Troy M.; Gorman, Ann Marie; Collingsworth, Paris D.; Warren, Glenn J.; Kocovsky, Patrick M.; Conroy, Joseph D.

    2015-01-01

    Seasonal degradation of aquatic habitats from hypoxia occurs in numerous freshwater and coastal marine systems and can result in direct mortality or displacement of fish. Yet, fishery landings from these systems are frequently unresponsive to changes in the severity and extent of hypoxia, and population-scale effects have been difficult to measure except in extreme hypoxic conditions with hypoxia-sensitive species. We investigated fine-scale temporal and spatial variability in dissolved oxygen in Lake Erie as it related to fish distribution and catch efficiencies of both active (bottom trawls) and passive (trap nets) fishing gears. Temperature and dissolved oxygen loggers placed near the edge of the hypolimnion exhibited much higher than expected variability. Hypoxic episodes of variable durations were frequently punctuated by periods of normoxia, consistent with high-frequency internal waves. High-resolution interpolations of water quality and hydroacoustic surveys suggest that fish habitat is compressed during hypoxic episodes, resulting in higher fish densities near the edges of hypoxia. At fixed locations with passive commercial fishing gear, catches with the highest values occurred when bottom waters were hypoxic for intermediate proportions of time. Proximity to hypoxia explained significant variation in bottom trawl catches, with higher catch rates near the edge of hypoxia. These results emphasize how hypoxia may elevate catch rates in various types of fishing gears, leading to a lack of association between indices of hypoxia and fishery landings. Increased catch rates of fish at the edges of hypoxia have important implications for stock assessment models that assume catchability is spatially homogeneous.

  12. U. S. GEOLOGICAL SURVEY LAND REMOTE SENSING ACTIVITIES.

    USGS Publications Warehouse

    Frederick, Doyle G.

    1983-01-01

    USGS uses all types of remotely sensed data, in combination with other sources of data, to support geologic analyses, hydrologic assessments, land cover mapping, image mapping, and applications research. Survey scientists use all types of remotely sensed data with ground verifications and digital topographic and cartographic data. A considerable amount of research is being done by Survey scientists on developing automated geographic information systems that can handle a wide variety of digital data. The Survey is also investigating the use of microprocessor computer systems for accessing, displaying, and analyzing digital data.

  13. Monocular distance estimation from optic flow during active landing maneuvers.

    PubMed

    van Breugel, Floris; Morgansen, Kristi; Dickinson, Michael H

    2014-06-01

    Vision is arguably the most widely used sensor for position and velocity estimation in animals, and it is increasingly used in robotic systems as well. Many animals use stereopsis and object recognition in order to make a true estimate of distance. For a tiny insect such as a fruit fly or honeybee, however, these methods fall short. Instead, an insect must rely on calculations of optic flow, which can provide a measure of the ratio of velocity to distance, but not either parameter independently. Nevertheless, flies and other insects are adept at landing on a variety of substrates, a behavior that inherently requires some form of distance estimation in order to trigger distance-appropriate motor actions such as deceleration or leg extension. Previous studies have shown that these behaviors are indeed under visual control, raising the question: how does an insect estimate distance solely using optic flow? In this paper we use a nonlinear control theoretic approach to propose a solution for this problem. Our algorithm takes advantage of visually controlled landing trajectories that have been observed in flies and honeybees. Finally, we implement our algorithm, which we term dynamic peering, using a camera mounted to a linear stage to demonstrate its real-world feasibility.

  14. Nonlinear Impact Dynamic Analysis and Comparison with Experimental Data for the Skid Gear

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Hyun; Kim, Yu-Sung

    In this study, nonlinear crash analyses have been conducted for the skid landing gear of helicopter. The realistic configuration of skid landing gear system is considered. Detailed three-dimensional finite element model with variable thickness and material nonlinearity is constructed for required impact design conditions. Advanced computational approach is used to conduct nonlinear transient impact dynamic analyses for different collision models. Characteristics of impact dynamic responses due to the ground crash are practically investigated in detail. It is also shown that the exact consideration of friction effect is very important to accurately predict the crash behavior of the skid type landing gear system. Finally, two typical landing conditions are analyzed and correlated with drop test results.

  15. A Comparative Study of Simulated and Measured Gear-Flap Flow Interaction

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R.; Mineck, Raymond E.; Yao, Chungsheng; Jenkins, Luther N.; Fares, Ehab

    2015-01-01

    The ability of two CFD solvers to accurately characterize the transient, complex, interacting flowfield asso-ciated with a realistic gear-flap configuration is assessed via comparison of simulated flow with experimental measurements. The simulated results, obtained with NASA's FUN3D and Exa's PowerFLOW® for a high-fidelity, 18% scale semi-span model of a Gulfstream aircraft in landing configuration (39 deg flap deflection, main landing gear on and off) are compared to two-dimensional and stereo particle image velocimetry measurements taken within the gear-flap flow interaction region during wind tunnel tests of the model. As part of the bench-marking process, direct comparisons of the mean and fluctuating velocity fields are presented in the form of planar contour plots and extracted line profiles at measurement planes in various orientations stationed in the main gear wake. The measurement planes in the vicinity of the flap side edge and downstream of the flap trailing edge are used to highlight the effects of gear presence on tip vortex development and the ability of the computational tools to accurately capture such effects. The present study indicates that both computed datasets contain enough detail to construct a relatively accurate depiction of gear-flap flow interaction. Such a finding increases confidence in using the simulated volumetric flow solutions to examine the behavior of pertinent aer-odynamic mechanisms within the gear-flap interaction zone.

  16. Parameter studies of gear cooling using an automatic finites element mesh generator

    NASA Technical Reports Server (NTRS)

    El-Bayoumy, L. E.; Akin, L. S.; Townsend, D. P.

    1984-01-01

    The range of accuracies achieved in the gear tooth temperature using an automatic finite element mesh generator were investigated. Gear web contribution to the gear cooling process was studied by introducing a varying size hole at the center of the gear because of the versatility of program TARG in allowing different heat transfer coefficients in different areas of the gear tooth. A study was carried out to evaluate the contribution of the loaded and unloaded faces as well as the top and bottom lands. A general purpose two-dimensional finite element preprocessor ATOGEN has been developed for automatic generation of a finite element mesh over a pie-shaped sector of a gear. The program was used for facilitating the input to an upgraded version of a previously developed program for the thermal analysis of running gears (TARG). The latter program determined the steady state temperature distribution throughout the specified gear. The automatic mesh generator program includes a band width minimization routine for reducing computer cost.

  17. The Dynamic Modelling of a Spur Gear in Mesh Including Friction and a Crack

    NASA Astrophysics Data System (ADS)

    Howard, Ian; Jia, Shengxiang; Wang, Jiande

    2001-09-01

    To improve the current generation of diagnostic techniques, many researchers are actively developing advanced dynamic models of gear case vibration to ascertain the effect of different types of gear train damage. This paper details a simplified gear dynamic model aimed at exploring the effect of friction on the resultant gear case vibration. The model incorporates the effect of variations in gear tooth torsional mesh stiffness, developed using finite element analysis, as the gears mesh together. The method of introducing the frictional force between teeth into the dynamic equations is given. The comparison between the results with friction and without friction was investigated using Matlab and Simulink models developed from the differential equations. The effects the single tooth crack has on the frequency spectrum and on the common diagnostic functions of the resulting gearbox component vibrations are also shown.

  18. A study of the optimum configuration of injection molded plastic gear by modification of gear tooth

    NASA Astrophysics Data System (ADS)

    Lee, Dae-Suep; Kwon, Young-Doo; Doc, Jin-Uk; Leed, Jun-Hyuk

    2009-07-01

    In this study, the gear system is optimized by modifying the tooth configuration of the plastic gears. Plastic gear is widely used as a machine element in industries of electric and electronic parts, automotive parts etc. Unlike the steel gear, the plastic gear has low load- transmission, durability and reliability. On the other hand, it is light-weight, low-noise, operable without a lubricant, shock absorptive, and anti-corrosive. The gear characteristics are calculated and analyzed by Hexagon and FEM (Finite Element Method) tools, and the characteristics of the standard gear and the addendum modified gear of the steel gear and the plastic gear are compared. When torque is applied to these gear systems, the system using the addendum modified gear can realize soft contact between gears. So, the noise of the addendum modified gear system was less than that of the common normal gear system. However, this is not applicable to any material, such as steel which is governed by DIN (Deuteshe Industrie Norm) recommendation. This study adopted the narrow tip tooth plastic gear, and proposed the optimum addendum modified gear with respect to stress, noise and contact ratio. To calculate and analyze the simulation of gear matching, we used commercial tools like CATIA, Auto-CAD, MARC for simulation and Hexagon for calculation.

  19. Gear shift control mechanism

    SciTech Connect

    Janson, D.A.

    1987-03-10

    A gear shift control mechanism is described comprising: multiple shift rods directed substantially parallel to one another, each rod carrying a shift fork for axial movement; a shift lever supported for pivotal movement about a first axis directed parallel to the axes of the shift rods and for pivotal movement about a second axis directed substantially perpendicular to the axes of the shift rods. The lever is moveable about the first axis and the second axis into engagement with a selected shift fork; interlock means located on each lateral side of the shift lever and mounted for pivotal movement about the first axis for blocking engagement with the shift forks; detent means for holding the shift lever in multiple predetermined angular positions about the second axis; and spring means located on a lateral side of the shift lever and mounted for pivotal movement about the first axis into interference contact with the shift forks for producing a force tending to resiliently bias the shift lever out of engagement with the selected shift fork.

  20. Molecular gearing systems

    DOE PAGES

    Gakh, Andrei A.; Sachleben, Richard A.; Bryan, Jeff C.

    1997-11-01

    The race to create smaller devices is fueling much of the research in electronics. The competition has intensified with the advent of microelectromechanical systems (MEMS), in which miniaturization is already reaching the dimensional limits imposed by physics of current lithographic techniques. Also, in the realm of biochemistry, evidence is accumulating that certain enzyme complexes are capable of very sophisticated modes of motion. Complex synergistic biochemical complexes driven by sophisticated biomechanical processes are quite common. Their biochemical functions are based on the interplay of mechanical and chemical processes, including allosteric effects. In addition, the complexity of this interplay far exceeds thatmore » of typical chemical reactions. Understanding the behavior of artificial molecular devices as well as complex natural molecular biomechanical systems is difficult. Fortunately, the problem can be successfully resolved by direct molecular engineering of simple molecular systems that can mimic desired mechanical or electronic devices. These molecular systems are called technomimetics (the name is derived, by analogy, from biomimetics). Several classes of molecular systems that can mimic mechanical, electronic, or other features of macroscopic devices have been successfully synthesized by conventional chemical methods during the past two decades. In this article we discuss only one class of such model devices: molecular gearing systems.« less

  1. Molecular gearing systems

    SciTech Connect

    Gakh, Andrei A.; Sachleben, Richard A.; Bryan, Jeff C.

    1997-11-01

    The race to create smaller devices is fueling much of the research in electronics. The competition has intensified with the advent of microelectromechanical systems (MEMS), in which miniaturization is already reaching the dimensional limits imposed by physics of current lithographic techniques. Also, in the realm of biochemistry, evidence is accumulating that certain enzyme complexes are capable of very sophisticated modes of motion. Complex synergistic biochemical complexes driven by sophisticated biomechanical processes are quite common. Their biochemical functions are based on the interplay of mechanical and chemical processes, including allosteric effects. In addition, the complexity of this interplay far exceeds that of typical chemical reactions. Understanding the behavior of artificial molecular devices as well as complex natural molecular biomechanical systems is difficult. Fortunately, the problem can be successfully resolved by direct molecular engineering of simple molecular systems that can mimic desired mechanical or electronic devices. These molecular systems are called technomimetics (the name is derived, by analogy, from biomimetics). Several classes of molecular systems that can mimic mechanical, electronic, or other features of macroscopic devices have been successfully synthesized by conventional chemical methods during the past two decades. In this article we discuss only one class of such model devices: molecular gearing systems.

  2. STS-66 landing at Edwards Air Force Base

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The main landing gear is on the ground and the nose gear is about to touch down as the Space Shuttle Atlantis heads toward a stop at Edwards Air Force Base in southern California, ending a successful 10 day, 22 hour and 34 minute space mission. Landing occured at 7:34 a.m. (PST), November 14, 1994.

  3. Advanced Face Gear Surface Durability Evaluations

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Heath, Gregory F.

    2016-01-01

    The surface durability life of helical face gears and isotropic super-finished (ISF) face gears was investigated. Experimental fatigue tests were performed at the NASA Glenn Research Center. Endurance tests were performed on 10 sets of helical face gears in mesh with tapered involute helical pinions, and 10 sets of ISF-enhanced straight face gears in mesh with tapered involute spur pinions. The results were compared to previous tests on straight face gears. The life of the ISF configuration was slightly less than that of previous tests on straight face gears. The life of the ISF configuration was slightly greater than that of the helical configuration.

  4. Contact Stress of Modified Curvilinear Gears

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Cheng; Gu, Ming-Lune

    2010-10-01

    The contact characteristics of a modified curvilinear gear set were investigated based on finite element analysis in this study. Firstly, the mathematical model of the modified curvilinear gears was developed based on the theory of gearing. Then a solid model of a modified curvilinear gear set was built by utilizing computer-aided design software. Finite element analysis enabled us to investigate the contact stress of a contact teeth pair. The variation and distribution of the contact stresses and bending stresses are also studied under different gear design parameters. Finally, illustrative examples were presented to demonstrate the contact characteristics of the modified curvilinear gears.

  5. 32. DETAIL VIEW OF PIVOT SPAN TURNTABLE, SHOWING MORTISE GEAR, ...

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

    32. DETAIL VIEW OF PIVOT SPAN TURNTABLE, SHOWING MORTISE GEAR, GEAR SHAFT, DRIVE GEAR AND BULL GEAR, LOOKING SOUTHEAST - Alton Bridge, Spanning Mississippi River between IL & MO, Alton, Madison County, IL

  6. 43 CFR 2884.25 - What activities may I conduct on BLM lands covered by my application for a grant or TUP while BLM...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false What activities may I conduct on BLM lands covered by my application for a grant or TUP while BLM is processing my application? 2884.25 Section 2884.25 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND...

  7. 43 CFR 2804.29 - What activities may I conduct on the lands covered by the proposed right-of-way while BLM is...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false What activities may I conduct on the lands covered by the proposed right-of-way while BLM is processing my application? 2804.29 Section 2804.29 Public Lands: Interior Regulations Relating to Public Lands (Continued) BUREAU OF LAND MANAGEMENT, DEPARTMENT OF THE INTERIOR LAND...

  8. Investigation into nitrided spur gears

    SciTech Connect

    Yilbas, B.S.; Coban, A.; Nickel, J.; Sunar, M.; Sami, M.; Abdul Aleem, B.J.

    1996-12-01

    The cold forging method has been widely used in industry to produce machine parts. In general, gears are produced by shaping or hobbing. One of the shaping techniques is precision forging, which has several advantages over hobbing. In the present study, cold forging of spur gears from Ti-6Al-4V material is introduced. To improve the surface properties of the resulting gears, plasma nitriding was carried out. Nuclear reaction analysis was carried out to obtain the nitrogen concentration, while the micro-PIXE technique was used to determine the elemental distribution in the matrix after forging and nitriding processes. Scanning electron microscopy and x-ray powder diffraction were used to investigate the metallurgical changes and formation of nitride components in the surface region. Microhardness and friction tests were carried out to measure the hardness depth profile and friction coefficient at the surface. Finally, scoring failure tests were conducted to determine the rotational speed at which the gears failed. Three distinct regions were obtained in the nitride region, and at the initial stages of the scoring tests, failure in surface roughness was observed in the vicinity of the tip of the gear tooth. This occurred at a particular rotational speed and work input.

  9. Planetary gear train of automatic transmission

    SciTech Connect

    Hiraiwa, K.

    1987-03-31

    A planetary gear train is described for an automatic transmission having input and output shafts, comprising: a first planetary gear unit including a first sun gear, a first internal gear and a first pinion carrier; a second planetary gear unit including a second sun gear, a second internal gear and a second pinion carrier, the first internal gear and the second pinion carrier being constantly connected to the output shaft; a first brake unit capable of braking the first and second sun gears which are connected to each other to rotate together; a clutch through which the first pinion carrier is connectable to the input shaft; a second brake unit capable of braking the first pinion carrier; a third brake unit capable of braking the second internal gear; and first and second groups of one-way means which are parallelly interposed between the input shaft and the first sun gear and arranged in a mutually reversed relationship so that the power transmission from the input shaft to the first sun gear and that from the first sun gear to the input shaft are respectively carried out by the first and second groups of one-way means.

  10. Handcycling: different modes and gear ratios.

    PubMed

    van der Woude, L H; Bosmans, I; Bervoets, B; Veeger, H E

    2000-01-01

    , increased static finger flexor and arm muscle activity may explain the increased strain in the somewhat unnatural heavy gear condition (24 rpm) at the studied velocity. Results need to be re-evaluated for wheelchair user populations and different higher velocities and power conditions. Moreover, other aspects of the wheelchair--user interface must be studied in order to generate optimum fitting and design guidelines for different user groups and conditions of use. PMID:11315650

  11. Transmission with two parallel driving shafts bearing two driving gears each meshed with same driven gear on parallel driven shaft

    SciTech Connect

    Akashi, T.; Ito, H.; Yamada, S.

    1986-06-17

    A transmission mechanism for a vehicle is described for receiving input of rotational power from a power supply member which rotates in a particular rotational direction and for outputting rotational power to a power receiving member which includes: an input member connected to the power supply member and which is rotatably mounted and receives supplying of the rotational power from the power supply member; a first driving gear wheel shaft; a second driving gear wheel shaft mounted generally parallel to the first driving gear wheel shaft; a driven gear wheel shaft mounted generally parallel to the first and second driving gear wheel shafts, the driven gear wheel shaft being rotationally connected to the power receiving member; a first driven gear wheel fixedly mounted on the driven gear wheel shaft; a first driving gear wheel which is rotatably mounted on the first driving gear wheel shaft and is constant mesh with the driven gear wheel, the first driving and driven gear wheels providing a first reduction gear ratio from the first driving gear wheel shaft to the driven gear wheel shaft; a second driven gear wheel fixedly mounted on the driven gear wheel shaft; a second driving gear wheel which is rotatably mounted on the second driving gear wheel shaft and is in constant mesh with the first driven gear wheel, the second driving and the first driven gear wheels providing a second reduction gear ratio smaller than the first reduction gear ratio from the second driving gear wheel shaft to the driven gear wheel shaft; a third driving gear wheel which is rotatably mounted on the first driving gear wheel shaft and is in constant mesh with the second driven gear wheel, the third driving and the second driven gear wheels providing a third reduction gear ratio smaller than the second reduction gear ratio from the first driving gear wheel shaft to the driven gear wheel shaft.

  12. Gear noise, vibration, and diagnostic studies at NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Zakrajsek, James J.; Oswald, Fred B.; Townsend, Dennis P.; Coy, John J.

    1990-01-01

    The NASA Lewis Research Center and the U.S. Army Aviation Systems Command are involved in a joint research program to advance the technology of rotorcraft transmissions. This program consists of analytical as well as experimental efforts to achieve the overall goals of reducing weight, noise, and vibration, while increasing life and reliability. Recent analytical activities are highlighted in the areas of gear noise, vibration, and diagnostics performed in-house and through NASA and U.S. Army sponsored grants and contracts. These activities include studies of gear tooth profiles to reduce transmission error and vibration as well as gear housing and rotordynamic modeling to reduce structural vibration transmission and noise radiation, and basic research into current gear failure diagnostic methodologies. Results of these activities are presented along with an overview of near term research plans in the gear noise, vibration, and diagnostics area.

  13. Gear noise, vibration, and diagnostic studies at NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Zakrajsek, J. J.; Oswald, F. B.; Townsend, D. P.; Coy, J. J.

    1990-01-01

    The NASA Lewis Research Center and the U.S. Army Aviation Systems Command are involved in a joint research program to advance the technology of rotorcraft transmissions. This program consists of analytical as well as experimental efforts to achieve the overall goals of reducing weight, noise, and vibration, while increasing life and reliability. Recent analytical activities are highlighted in the areas of gear noise, vibration, and diagnostics performed in-house and through NASA and U.S. Army sponsored grants and contracts. These activities include studies of gear tooth profiles to reduce transmission error and vibration as well as gear housing and rotordynamic modeling to reduce structural vibration and transmission and noise radiation, and basic research into current gear failure diagnostic methodologies. Results of these activities are presented along with an overview of near-term research plans in the gear noise, vibration, and diagnostics area.

  14. Swimming bacteria power microscopic gears.

    SciTech Connect

    Sokolov, A.; Apodaca, M. M.; Grzybowski, B. A.; Aranson, I. S.; Materials Science Division; Princeton Univ.; Northwestern Univ.

    2010-01-19

    Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be 'rectified' under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms.

  15. School Counseling Programs: Comparing GEAR UP Schools with Non-GEAR UP Schools

    ERIC Educational Resources Information Center

    Thorngren, Jill M.; Nelson, Mark D.; Baker, Larry J.

    2004-01-01

    A survey was conducted using qualitative means to assess school counseling programs in Montana. Schools that were demonstration schools in a federal initiative, Gaining Early Awareness and Readiness for Undergraduate Programs (GEAR UP) were compared to non-GEAR UP schools. Several differences between GEAR UP and non-GEAR UP schools are noted and…

  16. Development of a gear vibration indicator and its application in gear wear monitoring

    NASA Astrophysics Data System (ADS)

    Hu, Chongqing; Smith, Wade A.; Randall, Robert B.; Peng, Zhongxiao

    2016-08-01

    Gear tooth wear is an inevitable phenomenon and has a significant influence on gear dynamic features. Although vibration analysis has been widely used to diagnose localised gear tooth faults, its techniques for gear wear monitoring have not been well-established. This paper aims at developing a vibration indicator to evaluate the effects of wear on gear performance. For this purpose, a gear state vector is extracted from time synchronous averaged gear signals to describe the gear state. This gear state vector consists of the sideband ratios obtained from a number of tooth meshing harmonics and their sidebands. Then, two averaged logarithmic ratios, ALR and mALR, are defined with fixed and moving references, respectively, to provide complementary information for gear wear monitoring. Since a fixed reference is utilised in the definition of ALR, it reflects the cumulated wear effects on the gear state. An increase in the ALR value indicates that the gear state deviates further from its reference condition. With the use of a moving reference, the indicator mALR shows changes in the gear state within short time intervals, making it suitable for wear process monitoring. The efficiency of these vibration indicators is demonstrated using experimental results from two sets of tests, in which the gears experienced different wear processes. In addition to gear wear monitoring, the proposed indicators can be used as general parameters to detect the occurrence of other faults, such as a tooth crack or shaft misalignment, because these faults would also change the gear vibrations.

  17. Cloud — Aerosol interaction during lightning activity over land and ocean: Precipitation pattern assessment

    NASA Astrophysics Data System (ADS)

    Pal, Jayanti; Chaudhuri, Sutapa; Chowdhury, Arumita Roy; Bandyopadhyay, Tanuka

    2016-06-01

    The present study attempts to identify the land - ocean contrast in cloud - aerosol relation during lightning and non-lightning days and its effect on subsequent precipitation pattern. The thermal hypothesis in view of Convective Available Potential Energy (CAPE) behind the land - ocean contrast is observed to be insignificant in the present study region. The result shows that the lightning activities are significantly and positively correlated with aerosols over both land and ocean in case of low aerosol loading whereas for high aerosol loading the correlation is significant but, only over land. The study attempts to comprehend the mechanism through which the aerosol and lightning interact using the concept of aerosol indirect effect that includes the study of cloud effective radius, cloud fraction and precipitation rate. The result shows that the increase in lightning activity over ocean might have been caused due to the first aerosol indirect effect, while over land the aerosol indirect effect might have been suppressed due to lightning. Thus, depending on the region and relation between cloud parameters it is observed that the precipitation rate decreases (increases) over ocean during lightning (non-lightning) days. On the other hand during non-lightning days, the precipitation rate decreases over land.

  18. Microbial dynamics and enzyme activities in tropical Andosols depending on land use and nutrient inputs

    NASA Astrophysics Data System (ADS)

    Mganga, Kevin; Razavi, Bahar; Kuzyakov, Yakov

    2015-04-01

    Microbial decomposition of soil organic matter is mediated by enzymes and is a key source of terrestrial CO2 emissions. Microbial and enzyme activities are necessary to understand soil biochemical functioning and identify changes in soil quality. However, little is known about land use and nutrients availability effects on enzyme activities and microbial processes, especially in tropical soils of Africa. This study was conducted to examine how microbial and enzyme activities differ between different land uses and nutrient availability. As Andosols of Mt. Kilimanjaro are limited by nutrient concentrations, we hypothesize that N and P additions will stimulate enzyme activity. N and P were added to soil samples (0-20 cm) representing common land use types in East Africa: (1) savannah, (2) maize fields, (3) lower montane forest, (4) coffee plantation, (5) grasslands and (6) traditional Chagga homegardens. Total CO2 efflux from soil, microbial biomass and activities of β-glucosidase, cellobiohydrolase, chitinase and phosphatase involved in C, N and P cycling, respectively was monitored for 60 days. Total CO2 production, microbial biomass and enzyme activities varied in the order forest soils > grassland soils > arable soils. Increased β-glucosidase and cellobiohydrolase activities after N addition of grassland soils suggest that microorganisms increased N uptake and utilization to produce C-acquiring enzymes. Low N concentration in all soils inhibited chitinase activity. Depending on land use, N and P addition had an inhibitory or neutral effect on phosphatase activity. We attribute this to the high P retention of Andosols and low impact of N and P on the labile P fractions. Enhanced CO2 production after P addition suggests that increased P availability could stimulate soil organic matter biodegradation in Andosols. In conclusion, land use and nutrients influenced soil enzyme activities and microbial dynamics and demonstrated the decline in soil quality after landuse

  19. Sequencing device utilizing planetary gear set

    NASA Technical Reports Server (NTRS)

    Appleberry, W. T. (Inventor)

    1979-01-01

    A planetary (epicyclic) gear set is provided with a reversible rotating input shaft and individual outputs shafts actuated, respectively, by the ring gear and planet gear carrier. Latch means is positioned to selectively and automatically stop the ring gear or carrier member while releasing the other to provide the desired sequential output operation. The output shafts are reversed in sequence and direction of rotation by reversing rotational direction of the input shaft.

  20. Computer simulation of gear tooth manufacturing processes

    NASA Technical Reports Server (NTRS)

    Mavriplis, Dimitri; Huston, Ronald L.

    1990-01-01

    The use of computer graphics to simulate gear tooth manufacturing procedures is discussed. An analytical basis for the simulation is established for spur gears. The simulation itself, however, is developed not only for spur gears, but for straight bevel gears as well. The applications of the developed procedure extend from the development of finite element models of heretofore intractable geometrical forms, to exploring the fabrication of nonstandard tooth forms.

  1. Do Neighborhood Physical Activity Resources and Land Use Influence Physical Activity among African American Public Housing Residents?

    PubMed

    Parker, Nathan H; O'Connor, Daniel P; Kao, Dennis T; Lee, Rebecca E

    2016-01-01

    Few studies have examined neighborhood influences on physical activity (PA) among low-income African Americans living in public housing. This study measured the associations of PA resources and land use with PA among 216 African Americans living in 12 low-income housing developments in Houston, Texas. Neighborhood measures included both detailed information from in-person audits and geographic information systems (GIS) data. Hierarchical linear regression models tested the associations of neighborhood PA resource availability and quality and land use density and diversity with individual-level, self-reported PA. Land use diversity was positively associated with walking among men after controlling for other neighborhood characteristics. Policies that promote land use diversity or improve the pedestrian environment in areas with diverse destinations may encourage PA among public housing residents. PMID:27524771

  2. Maximum life spur gear design

    NASA Technical Reports Server (NTRS)

    Savage, M.; Mackulin, B. J.; Coe, H. H.; Coy, J. J.

    1991-01-01

    Optimization procedures allow one to design a spur gear reduction for maximum life and other end use criteria. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial guess values. The optimization algorithm is described, and the models for gear life and performance are presented. The algorithm is compact and has been programmed for execution on a desk top computer. Two examples are presented to illustrate the method and its application.

  3. A Review of Land-Cover Mapping Activities in Coastal Alabama and Mississippi

    USGS Publications Warehouse

    Smith, Kathryn E.L.; Nayegandhi, Amar; Brock, John C.

    2010-01-01

    INTRODUCTION Land-use and land-cover (LULC) data provide important information for environmental management. Data pertaining to land-cover and land-management activities are a common requirement for spatial analyses, such as watershed modeling, climate change, and hazard assessment. In coastal areas, land development, storms, and shoreline modification amplify the need for frequent and detailed land-cover datasets. The northern Gulf of Mexico coastal area is no exception. The impact of severe storms, increases in urban area, dramatic changes in land cover, and loss of coastal-wetland habitat all indicate a vital need for reliable and comparable land-cover data. Four main attributes define a land-cover dataset: the date/time of data collection, the spatial resolution, the type of classification, and the source data. The source data are the foundation dataset used to generate LULC classification and are typically remotely sensed data, such as aerial photography or satellite imagery. These source data have a large influence on the final LULC data product, so much so that one can classify LULC datasets into two general groups: LULC data derived from aerial photography and LULC data derived from satellite imagery. The final LULC data can be converted from one format to another (for instance, vector LULC data can be converted into raster data for analysis purposes, and vice versa), but each subsequent dataset maintains the imprint of the source medium within its spatial accuracy and data features. The source data will also influence the spatial and temporal resolution, as well as the type of classification. The intended application of the LULC data typically defines the type of source data and methodology, with satellite imagery being selected for large landscapes (state-wide, national data products) and repeatability (environmental monitoring and change analysis). The coarse spatial scale and lack of refined land-use categories are typical drawbacks to satellite

  4. Gear teeth impacts in hydrodynamic conjunctions promoting idle gear rattle

    NASA Astrophysics Data System (ADS)

    Theodossiades, S.; Tangasawi, O.; Rahnejat, H.

    2007-06-01

    The rattle phenomenon in vehicular transmissions and its impact on the automotive industry have been widely reported in the literature. A variety of palliative measures have been suggested for attenuation of rattle such as use of backlash eliminators, clutch dampers or dual-mass flywheels. These palliative measures incur further costs and can have untoward implications in powertrain noise and vibration problems. A fundamental investigation of the dynamics of impacting gears is undoubtedly the way forward for a root cause solution. This paper introduces a new approach for understanding the interactions between the transmission gears during engine idle conditions by taking into account the effect of lubrication. Gear impacting surfaces are treated as lubricated conjunctions rather than the usually reported dry impacting solids. Depending on load and speed of entraining motion of the lubricant into the contact domains, the regime of lubrication alters. In this paper, the influence of lubricant in torsional vibration of lightly loaded idling gears is examined which promotes iso-viscous hydrodynamic conditions. It is shown that the lubricant film under these conditions behaves as a time-varying nonlinear spring-damper element. Spectral analysis of the system response is compared to the findings of the linearised system.

  5. 50 CFR 622.272 - Authorized gear.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF COMMERCE FISHERIES OF THE CARIBBEAN, GULF OF MEXICO, AND SOUTH ATLANTIC Dolphin and Wahoo Fishery Off the Atlantic States § 622.272 Authorized gear. (a) Atlantic dolphin and wahoo—(1) Authorized gear. The following are the only authorized gear types in the fisheries for dolphin and wahoo in...

  6. 50 CFR 622.272 - Authorized gear.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., DEPARTMENT OF COMMERCE FISHERIES OF THE CARIBBEAN, GULF OF MEXICO, AND SOUTH ATLANTIC Dolphin and Wahoo Fishery Off the Atlantic States § 622.272 Authorized gear. (a) Atlantic dolphin and wahoo—(1) Authorized gear. The following are the only authorized gear types in the fisheries for dolphin and wahoo in...

  7. 50 CFR 648.163 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Gear restrictions. 648.163 Section 648... Atlantic Bluefish Fishery § 648.163 Gear restrictions. Link to an amendment published at 76 FR 60640, Sept... gear restrictions are necessary to assure that the fishing mortality rate is not exceeded, or to...

  8. 50 CFR 665.605 - Gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Gear restrictions. 665.605 Section 665... Fisheries § 665.605 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for PRIA bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  9. 50 CFR 665.804 - Gear identification.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Gear identification. 665.804 Section 665... Fisheries § 665.804 Gear identification. (a) Identification. The operator of each permitted vessel in the... action. Longline gear not marked in compliance with paragraph (a) of this section and found deployed...

  10. 50 CFR 660.506 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear restrictions. 660.506 Section 660.506 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 660.506 Gear restrictions. The only fishing gear authorized for use in the reduction fishery...

  11. 50 CFR 665.104 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear restrictions. 665.104 Section 665... § 665.104 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for American Samoa bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  12. 50 CFR 665.804 - Gear identification.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear identification. 665.804 Section 665... Fisheries § 665.804 Gear identification. (a) Identification. The operator of each permitted vessel in the... action. Longline gear not marked in compliance with paragraph (a) of this section and found deployed...

  13. 50 CFR 665.164 - Gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Gear restrictions. 665.164 Section 665.164 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 665.164 Gear restrictions. Only selective gear may be used to harvest coral from any precious...

  14. 50 CFR 665.605 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear restrictions. 665.605 Section 665... Fisheries § 665.605 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for PRIA bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  15. 50 CFR 660.506 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Gear restrictions. 660.506 Section 660.506..., DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES Coastal Pelagics Fisheries § 660.506 Gear restrictions. The only fishing gear authorized for use in the reduction fishery for northern anchovy...

  16. 50 CFR 665.264 - Gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Gear restrictions. 665.264 Section 665.264 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Gear restrictions. Only selective gear may be used to harvest coral from any precious coral permit area....

  17. 50 CFR 665.605 - Gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear restrictions. 665.605 Section 665... Fisheries § 665.605 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for PRIA bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  18. 50 CFR 665.164 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear restrictions. 665.164 Section 665.164 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 665.164 Gear restrictions. Only selective gear may be used to harvest coral from any precious...

  19. 50 CFR 665.164 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear restrictions. 665.164 Section 665.164 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 665.164 Gear restrictions. Only selective gear may be used to harvest coral from any precious...

  20. 50 CFR 665.164 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Gear restrictions. 665.164 Section 665.164..., DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES IN THE WESTERN PACIFIC American Samoa Fisheries § 665.164 Gear restrictions. Only selective gear may be used to harvest coral from any precious coral permit area....

  1. 50 CFR 660.506 - Gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear restrictions. 660.506 Section 660.506 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 660.506 Gear restrictions. The only fishing gear authorized for use in the reduction fishery...

  2. 50 CFR 665.264 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear restrictions. 665.264 Section 665.264 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Gear restrictions. Only selective gear may be used to harvest coral from any precious coral permit area....

  3. 50 CFR 665.804 - Gear identification.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear identification. 665.804 Section 665... Fisheries § 665.804 Gear identification. (a) Identification. The operator of each permitted vessel in the... action. Longline gear not marked in compliance with paragraph (a) of this section and found deployed...

  4. 50 CFR 665.804 - Gear identification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear identification. 665.804 Section 665... Fisheries § 665.804 Gear identification. (a) Identification. The operator of each permitted vessel in the... action. Longline gear not marked in compliance with paragraph (a) of this section and found deployed...

  5. 50 CFR 665.264 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Gear restrictions. 665.264 Section 665.264..., DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES IN THE WESTERN PACIFIC Hawaii Fisheries § 665.264 Gear restrictions. Only selective gear may be used to harvest coral from any precious coral permit area....

  6. 50 CFR 665.664 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Gear restrictions. 665.664 Section 665.664 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION... § 665.664 Gear restrictions. Only selective gear may be used to harvest coral from any precious...

  7. 50 CFR 665.264 - Gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear restrictions. 665.264 Section 665.264 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Gear restrictions. Only selective gear may be used to harvest coral from any precious coral permit area....

  8. 50 CFR 660.506 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear restrictions. 660.506 Section 660.506 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 660.506 Gear restrictions. The only fishing gear authorized for use in the reduction fishery...

  9. 50 CFR 665.664 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear restrictions. 665.664 Section 665.664 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Fisheries § 665.664 Gear restrictions. Only selective gear may be used to harvest coral from any...

  10. 50 CFR 665.104 - Gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear restrictions. 665.104 Section 665... § 665.104 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for American Samoa bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  11. 50 CFR 665.804 - Gear identification.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Gear identification. 665.804 Section 665... Fisheries § 665.804 Gear identification. (a) Identification. The operator of each permitted vessel in the... action. Longline gear not marked in compliance with paragraph (a) of this section and found deployed...

  12. 50 CFR 665.605 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear restrictions. 665.605 Section 665... Fisheries § 665.605 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for PRIA bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  13. 50 CFR 665.605 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Gear restrictions. 665.605 Section 665.605... § 665.605 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for PRIA bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear. Possession of...

  14. 50 CFR 665.264 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear restrictions. 665.264 Section 665.264 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Gear restrictions. Only selective gear may be used to harvest coral from any precious coral permit area....

  15. 50 CFR 665.164 - Gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear restrictions. 665.164 Section 665.164 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... § 665.164 Gear restrictions. Only selective gear may be used to harvest coral from any precious...

  16. 50 CFR 665.664 - Gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Gear restrictions. 665.664 Section 665.664 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Fisheries § 665.664 Gear restrictions. Only selective gear may be used to harvest coral from any...

  17. 50 CFR 665.104 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Gear restrictions. 665.104 Section 665... § 665.104 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for American Samoa bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  18. 50 CFR 648.163 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Gear restrictions. 648.163 Section 648.163... Bluefish Fishery § 648.163 Gear restrictions. If the Council determines through its annual review or framework adjustment process that gear restrictions are necessary to assure that the fishing mortality...

  19. 50 CFR 665.104 - Gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Gear restrictions. 665.104 Section 665... § 665.104 Gear restrictions. (a) Bottom trawls and bottom set gillnets. Fishing for American Samoa bottomfish MUS with bottom trawls and bottom set gillnets is prohibited. (b) Possession of gear....

  20. 50 CFR 665.664 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Gear restrictions. 665.664 Section 665.664 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Fisheries § 665.664 Gear restrictions. Only selective gear may be used to harvest coral from any...

  1. 50 CFR 665.664 - Gear restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Gear restrictions. 665.664 Section 665.664 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Fisheries § 665.664 Gear restrictions. Only selective gear may be used to harvest coral from any...

  2. 50 CFR 648.203 - Gear restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Atlantic Herring Fishery § 648.203 Gear restrictions. (a) Midwater trawl gear may only be used by a vessel issued a valid herring permit in the GOM/GB Exemption Area as defined in § 648.80(a)(17), and in the... a Letter of Authorization. (b) Purse seine gear may only be used by a vessel issued a valid...

  3. 50 CFR 648.203 - Gear restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Atlantic Herring Fishery § 648.203 Gear restrictions. (a) Midwater trawl gear may only be used by a vessel issued a valid herring permit in the GOM/GB Exemption Area as defined in § 648.80(a)(17), and in the... a Letter of Authorization. (b) Purse seine gear may only be used by a vessel issued a valid...

  4. 50 CFR 648.203 - Gear restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Herring Fishery § 648.203 Gear restrictions. (a) Midwater trawl gear may only be used by a vessel issued a valid herring permit in the GOM/GB Exemption Area as defined in § 648.80(a)(17), and in the Nantucket... Authorization. (b) Purse seine gear may only be used by a vessel issued a valid herring permit in the...

  5. 50 CFR 648.203 - Gear restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Atlantic Herring Fishery § 648.203 Gear restrictions. (a) Midwater trawl gear may only be used by a vessel issued a valid herring permit in the GOM/GB Exemption Area as defined in § 648.80(a)(17), and in the... a Letter of Authorization. (b) Purse seine gear may only be used by a vessel issued a valid...

  6. Modification Of Gear Teeth To Reduce Vibrations

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Oswald, Fred B.; Lin, Hsiang Hsi

    1990-01-01

    Computer simulations yield data useful in designing for low noise. Effects of modifications in shape of gear teeth upon static transmission error and dynamic loading of gears now analyzed systematically. Design curves generated by conducting numerical simulations of dynamic effects at successive incremental modifications of gear systems operated at various applied loads. Modifications that result in minimum dynamic effect determined from design curves.

  7. Fixed Foot Balance Training Increases Rectus Femoris Activation During Landing and Jump Height in Recreationally Active Women

    PubMed Central

    Kean, Crystal O.; Behm, David G.; Young, Warren B.

    2006-01-01

    The objective of this study was to determine the effects of fixed foot and functionally directed balance training on static balance time, muscle activation during landing, vertical jump height and sprint time. Twenty-four recreationally active females were tested pre- and post-training (fixed foot balance training, n= 11, functionally directed balance training, n = 7 and control group, n = 6). Experimental subjects completed either fixed foot or functionally directed balance exercises 4 times/week for 6 weeks. Surface electromyography (EMG) was used to assess preparatory and reactive muscle activity of the rectus femoris (RF), biceps femoris (BF), and the soleus during one- and two-foot landings following a jump. Maximum vertical jump height, static balance and 20-meter sprint times were also examined. The fixed foot balance-training group showed a 33% improvement (p < 0.05) in static balance time and 9% improvement in jump height. Neither type of training improved sprint times. Further analysis revealed significant (p < 0.05) overall (data collapsed over groups and legs) increases in reactive RF activity when landing. Independently, the fixed foot balance group showed a 33% increase in reactive RF activity (p < 0.01). Overall, there was also significantly less reactive co-activation following training (p < 0.05). It appears that fixed foot balance training for recreationally active women may provide greater RF activity when landing and increased countermovement jump height. Key points Balance training increased rectus femoris EMG activity upon landing from a stride. Fixed foot balance training improved countermovement jump height. Neither fixed foot nor functionally directed balance training elicited changes in sprint times. PMID:24198691

  8. Brain activity in predictive sensorimotor control for landings: an EEG pilot study.

    PubMed

    Baumeister, J; von Detten, S; van Niekerk, S-M; Schubert, M; Ageberg, E; Louw, Q A

    2013-12-01

    Landing from a jump is related to predictive sensorimotor control. Frontal, central and parietal brain areas are known to play a role in this process based on online sensory feedback. This can be measured by EEG. However, there is only limited knowledge about brain activity during predictive preparation for drop landings (DL). The purpose is to demonstrate changes in brain activity in preparation for DL in different conditions. After resting, 10 athletes performed a series of DLs and were asked to concentrate on the landing preparation for 10 s before an auditory signal required them to drop land from a 30 cm platform. This task was executed before and after a standardized fatigue protocol. EEG spectral power was calculated during DL preparation. Frontal Theta power was increased during preparation compared to rest. Parietal Alpha-2 power demonstrated higher values in preparation after fatigue condition while lower limb kinematics remained unchanged. Cortical activity in frontal and parietal brain areas is sensitive for predictive sensorimotor control of drop landings. Frontal Theta power demonstrates an increase and is related to higher attentional control. In a fatigued condition the parietal Alpha-2 power increase might be related to a deactivation in the somatosensory brain areas. PMID:23740338

  9. Brain activity in predictive sensorimotor control for landings: an EEG pilot study.

    PubMed

    Baumeister, J; von Detten, S; van Niekerk, S-M; Schubert, M; Ageberg, E; Louw, Q A

    2013-12-01

    Landing from a jump is related to predictive sensorimotor control. Frontal, central and parietal brain areas are known to play a role in this process based on online sensory feedback. This can be measured by EEG. However, there is only limited knowledge about brain activity during predictive preparation for drop landings (DL). The purpose is to demonstrate changes in brain activity in preparation for DL in different conditions. After resting, 10 athletes performed a series of DLs and were asked to concentrate on the landing preparation for 10 s before an auditory signal required them to drop land from a 30 cm platform. This task was executed before and after a standardized fatigue protocol. EEG spectral power was calculated during DL preparation. Frontal Theta power was increased during preparation compared to rest. Parietal Alpha-2 power demonstrated higher values in preparation after fatigue condition while lower limb kinematics remained unchanged. Cortical activity in frontal and parietal brain areas is sensitive for predictive sensorimotor control of drop landings. Frontal Theta power demonstrates an increase and is related to higher attentional control. In a fatigued condition the parietal Alpha-2 power increase might be related to a deactivation in the somatosensory brain areas.

  10. NASA Langley's Aircraft Landing Dynamics Facility

    NASA Technical Reports Server (NTRS)

    Davis, Pamela A.

    1993-01-01

    The Aircraft Landing Dynamics Facility (ALDF) is a unique facility with the ability to test aircraft landing gear systems on actual runway surfaces at operational ground speeds and loading conditions. A brief historical overview of the original Landing Loads Track (LLT) is given, followed by a detailed description of the new ALDF systems and operational capabilities.

  11. Illinois Shifting Gears Policy Evaluation

    ERIC Educational Resources Information Center

    Weitzel, Peter C.

    2009-01-01

    Illinois Shifting Gears is a multilevel initiative that has simultaneously created bridge programs in the field and altered state policy to facilitate the creation of more programs in the future. These efforts have informed each other, giving policymakers the opportunity to interact with practitioners, troubleshoot bridge programs, and make…

  12. GEAR UP Aspirations Project Evaluation

    ERIC Educational Resources Information Center

    Trimble, Brad A.

    2013-01-01

    The purpose of this study was to conduct a formative evaluation of the first two years of the Gaining Early Awareness and Readiness for Undergraduate Programs (GEAR UP) Aspirations Project (Aspirations) using a Context, Input, Process, and Product (CIPP) model so as to gain an in-depth understanding of the project during the middle school…

  13. Recent manufacturing advances for spiral bevel gears

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Bill, Robert C.

    1991-01-01

    The U.S. Army Aviation Systems Command (AVSCOM), through the Propulsion Directorate at NASA Lewis Research Center, has recently sponsored projects to advance the manufacturing process for spiral bevel gears. This type of gear is a critical component in rotary-wing propulsion systems. Two successfully completed contracted projects are described. The first project addresses the automated inspection of spiral bevel gears through the use of coordinate measuring machines. The second project entails the computer-numerical-control (CNC) conversion of a spiral bevel gear grinding machine that is used for all aerospace spiral bevel gears. The results of these projects are described with regard to the savings effected in manufacturing time.

  14. Recent manufacturing advances for spiral bevel gears

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Bill, Robert C.

    1991-01-01

    The U.S. Army Aviation Systems Command (AVSCOM), through the Propulsion Directorate at NASA LRC, has recently sponsored projects to advance the manufacturing process for spiral bevel gears. This type of gear is a critical component in rotary-wing propulsion systems. Two successfully completed contracted projects are described. The first project addresses the automated inspection of spiral bevel gears through the use of coordinate measuring machines. The second project entails the computer-numerical-control (CNC) conversion of a spiral bevel gear grinding machine that is used for all aerospace spiral bevel gears. The results of these projects are described with regard to the savings effected in manufacturing time.

  15. Quadriceps and hamstrings prelanding myoelectric activity during landing from different heights among male and female athletes.

    PubMed

    de Britto, Morgana Alves; Carpes, Felipe P; Koutras, Georgios; Pappas, Evangelos

    2014-08-01

    ACL tear is a major concern among athletes, coaches and sports scientists. More than taking the athlete away from training and competition, ACL tear is a risk factor for early-onset of knee osteoarthritis, and, therefore addressing strategies to avoid such injury is pertinent not only for competitive athletes, but for all physically active subjects. Imbalances in the prelanding myoelectric activity of the hamstrings and quadriceps muscles have been linked to ACL injuries. We investigated the effect of landing from different heights on prelanding myoelectric activity of the hamstrings and quadriceps muscles in recreational athletes. Thirty recreational athletes (15 male and 15 female) performed three bilateral drop jumps from two different heights; 20cm and 40cm while myoelectric activity of the vastus medialis, rectus femoris, biceps femoris and medial hamstrings were collected. When increasing the height of drop landing tasks prelanding normalized myoelectric activity of the quadriceps was increased by 15-20% but no significant changes were found for the hamstrings. Female athletes exhibited higher activity of the medial hamstrings compared to their male counterparts. We concluded that increasing the height of drop landing tasks is associated with increased myoelectric activity of the quadriceps but not the hamstrings in recreational athletes. These differences in muscle activity may be related to increased risk for ACL injury when the height is increased. Female athletes demonstrated higher recruitment of the medial hamstrings.

  16. Experimentation Toward the Analysis of Gear Noise Sources Controlled by Sliding Friction and Surface Roughness

    NASA Technical Reports Server (NTRS)

    Asnani, Vivake M.

    2004-01-01

    In helicopters and other rotorcraft, the gearbox is a major source of noise and vibration (N&V). The two N&V excitation mechanisms are the relative displacements between mating gears (transmission errors) and the friction associated with sliding between gear teeth. Historically, transmission errors have been minimized via improved manufacturing accuracies and tooth modifications. Yet, at high torque loads, noise levels are still relatively high though transmission errors might be somewhat minimal. This suggests that sliding friction is indeed a dominant noise source for high power density rotorcraft gearboxes. In reality, friction source mechanism is associated with surface roughness, lubrication regime properties, time-varying friction forces/torques and gear-mesh interface dynamics. Currently, the nature of these mechanisms is not well understood, while there is a definite need for analytical tools that incorporate sliding resistance and surface roughness, and predict their effects on the vibro- acoustic behavior of gears. Toward this end, an experiment was conducted to collect sound and vibration data on the NASA Glenn Gear-Noise Rig. Three iterations of the experiment were accomplished: Iteration 1 tested a baseline set of gears to establish a benchmark. Iteration 2 used a gear-set with low surface asperities to reduce the sliding friction excitation. Iteration 3 incorporated low viscosity oil with the baseline set of gears to examine the effect of lubrication. The results from this experiment will contribute to a two year project in collaboration with the Ohio State University to develop the necessary mathematical and computer models for analyzing geared systems and explain key physical phenomena seen in experiments. Given the importance of sliding friction in the gear dynamic and vibro-acoustic behavior of rotorcraft gearboxes, there is considerable potential for research & developmental activities. Better models and understanding will lead to quiet and

  17. Driving gear for front and rear wheels of automobile

    SciTech Connect

    Ashikawa, N.; Sakuma, S.

    1986-10-21

    A driving gear is described for front and rear wheels of an automobile, comprising an engine with a crank shaft disposed in a direction of width of a body of the automobile, a transmission supported on an engine case at one side axially of the crank shaft, and a clutch provided between the engine and the transmission. The driving gear includes a first differential gear of a planetary gear type coupled to the transmission via a reduction gear, a second differential gear of a bevel gear type transmission an output of the first differential gear to left and right front wheels of the automobile, and a third differential gear transmitting an output of the first differential gear to left and right rear wheels of the automobile. The first differential gear is disposed adjacent to the reduction gear and comprises a sun gear, a ring gear and planet gears engaging with the sun and ring gears. The planet gears are pivoted directly on and driven by the reduction gear; the first and second differential gears are provided on opposite sides of a plane perpendicular to the crankshaft and including the clutch. The first and second differential gears also lie along a common axis parallel to the crank shaft. The sun gear and the ring gear are coupled individually to the front and rear wheels respectively.

  18. 76 FR 2917 - Agency Information Collection Activities: Canadian Border Boat Landing Permit (CBP Form I-68)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... proposed information collection was previously published in the Federal Register (75 FR 61508) on October 5... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Canadian Border Boat Landing Permit (CBP Form I-68) AGENCY: U.S. Customs and Border Protection, Department of Homeland...

  19. Apparatus for controlling automatic gear transmission

    SciTech Connect

    Yoshimura, H.; Iida, Y.

    1989-04-25

    An apparatus is described for controlling an automatic gear transmission of a motor vehicle having an engine with an output and being subjected to a running resistance, the automatic gear transmission having a present gear position the apparatus comprising: arithmetic means, operatively connected to receive an optimum gear position, for computing a maximum output of the engine for the present gear position if the optimum gear position is the present gear position; arithmetic means, operatively connected to receive an optimum gear position, for computing an engine output corresponding to the running resistance of the motor vehicle for the present gear position; comparison means for comparing the computed maximum output of the engine and the computed engine output; and command modifying means for modifying the optimum gear position to a lower gear position and commanding a shiftdown when the computed engine output corresponding to running resistance is larger than the computed maximum engine output based on the result of comparison effected by the comparison means.

  20. Thermal influence on precise gear transmission

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Fei, Yetai; Miao, EnMing; Zhang, Xiao-rou

    2013-01-01

    Conjugate meshing of involute gears is required in precise gear transmission. However, in the working process, the heat generated in friction results in deformation of the tooth profile of the gear, radial and axial deformation of the shaft and bearing. Meanwhile, there is thermal deformation with non-similarity in the gear box that the shafts and bearings are installed on, which leads to a change of the bearing clearance, axis deflection of the shaft and the gear meshing state. As a result of all these effects, vibration and noise are generated in the transmission system, and it intensifies the possibility of damaging the parts. In this paper, mathematical physics methods and thermal elastic theory are employed to analyze the influence of tooth profiles, gear parameters (transmission ratio i, overlapping coefficients ɛ, backlash jn, etc), gear meshing, working clearance of the bearing (it relates with the initial clearance, tolerance matching, rotational speed, temperature changes, etc) and the shape of the gear box (cylindricity error, axis deflection, etc) caused by the temperature change. The result can be employed in selecting gear parameters and designing the shape of the gear tooth, bearing clearance and shell structure, and it is also helpful to the design of gear transmissions and screw transmissions.

  1. Gear-change apparatus for vehicle transmission

    SciTech Connect

    Kuratsu, H.; Yoshimura, Y.; Sekine, N.; Kima, Y.

    1988-11-22

    This patent describes a gear-change apparatus for a vehicular transmission having forward gear trains each established through an associated synchronizing mechanism, and a reverse gear train established by axial movement on a shaft of a reverse idler gear, an improvement comprising: a cam mechanism having a first cam fixed in place on a reverse shift fork for shifting the reverse idler gear from an inoperative position to an engaged reverse gear train position thereof and, a second cam fixed in place on a forward shift fork for establishing one forward gear train, the first and second cams being arranged such that when the reverse shift fork is moved in a direction which causes the first cam to engage the second cam the forward shift fork is shifted by a predetermined small stroke sufficient for the synchronizing mechanism of that one forward gear corresponding to the forward shift fork to effect only the synchronizing action thereof in response to the movement of the reverse shift fork from the inoperative position of the reverse idler gear to a position immediately before the engaged reverse gear train position of the reverse idler gear.

  2. 50 CFR 300.35 - Vessel and gear identification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Section 300.35 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS South Pacific Tuna Fisheries § 300.35 Vessel and gear identification. While a vessel is in the Licensing Area, a Limited Area closed to fishing, or a Closed Area, a recent and up-to-date copy of...

  3. Validation and Verification of the Operational Land Analysis Activities at the Air Force Weather Agency

    NASA Astrophysics Data System (ADS)

    Shaw, M.; Kumar, S.; Peters-Lidard, C. D.; Cetola, J.

    2011-12-01

    The importance of operational benchmarking and uncertainty characterization of land surface modeling can be clear upon considering the wide range of performance characteristics of numerical land surface models realizable through various combinations of factors. Such factors might include model physics and numerics, resolution, and forcing datasets used in operational implementation versus those that might have been involved in any prior development benchmarking. Of course, decisions concerning operational implementation may be better informed through more effective benchmarking of performance under various blends of such aforementioned operational factors. To facilitate this and other needs for land analysis activities at the Air Force Weather Agency (AFWA), the Model Evaluation Toolkit (MET) - a joint product of the National Center for Atmospheric Research Developmental Testbed Center (NCAR DTC), AFWA, and the user community - and the land information system (LIS) Verification Toolkit (LVT) - developed at the Goddard Space Flight Center (GSFC) - have been adapted to the operational benchmarking needs of AFWA's land characterization activities in order to compare the performance of new land modeling and related activities with that of previous activities as well as observational or analyzed datasets. In this talk, three examples of adaptations of MET and LVT to evaluation of LIS-related operations at AFWA will be presented. One example will include comparisons of new surface rainfall analysis capabilities, towards forcing of AFWA's LIS, with previous capabilities. Comparisons will be relative to retrieval-, model-, and measurement-based precipitation fields. Results generated via MET's grid-stat, neighborhood, wavelet, and object based evaluation (MODE) utilities adapted to AFWA's needs will be discussed. This example will be framed in the context of better informing optimal blends of land surface model (LSM) forcing data sources - namely precipitation data- under

  4. [Effects of Different Land Uses on Soil Active Organic Carbon and Nitrogen Fractions in Jinyun Mountain].

    PubMed

    Qi, Xin; Jiang, Chang-sheng; Hao, Qing-ju; Li, Jian-lin

    2015-10-01

    In this paper, we take Jinyun Mountain where located in Beibei district of Chongqing as the research object and explore the effect of different ways of land use on soil active organic carbon, nitrogen components by collecting the soil samples from 0 to 60 cm depth in subtropical evergreen broad-leaved forest (hereinafter referred to as the forest), abandoned land, orchard, farmland and measuring the content of MBC, MBN, DOC and DON. The research results show that the contents of soil MBC, MBN, DOC, DON are reduced with the increase of soil depth in four types of land using soils. Variance analysis of the single factor shows that four kinds of land uses have no significant difference in the contents of MBC, MBN and DON, but the DOC content of the abandoned land is significantly higher than that of other three kinds. It shows that the different ways of land use have no obvious effects on soil MBC, MBN and DON but the abandonment of slope cropland can significantly increase the content of soil DOC. There is no significant difference among the distribution ratio of MBN, DOC, DON in forest, abandoned land, orchard and farmland within the soil from 0 to 60 cm, but the distribution ratio of slope MBC is significantly higher than that of other three kinds. It means farmland soil organic carbon has a higher biological activity, this could due to the application of green manure, farmland manure and other organic fertilizers. Under different land utilizations, DOC/DON is the highest, MBC/MBN is the second, and SOC/TN is the lowest. It means the biological solidification of dissolved organic matter is the strongest, and the mineralization of soil organic matter is the most obvious. Under the four kinds of land uses, there are the lowest ratios in SOC/TN, MBC/MBN and DOC/DON in the farmland. And all the ratios are less than 20, which suggest that the mineralization of farmland soil organic matter is stronger and it's easy to cause the loss of soil carbon.

  5. Relationship between gear ratio and 10-s sprint cycling on an air-braked ergometer.

    PubMed

    Barnett, C; Jenkins, D G; Mackinnon, L T

    1996-01-01

    This investigation examined the relationship between gear ratio and peak and mean power outputs (PPO and MPO) and peak cadence (PC) during a 10-s all-out sprint on a multi-geared air-braked cycle ergometer. Ten physically active men [mean age 21.0 years (SEM 0.7)] performed in random order six 10-s sprints (15-min rest between each sprint) on two occasions (48 h apart) in six different gear ratios; flywheel revolutions per pedal crank revolution (FR/PCR) ranged between 5.22 and 11.61. The PPO, MPO, and PC were recorded from each sprint. Of the six gear ratios tested, a gear ratio eliciting 8.87 FR/PCR elicited the highest PPO for the initial test session; the PPO output of 1274 W was significantly greater (P < 0.01) than that produced in the other five gears. Analysis of data from the second test session revealed no statistically significant difference in PPO between gear ratios eliciting 8.00, 8.87, and 10.06 FR/PCR. The PPO from these three ratios were significantly greater (P < 0.05) than those produced using the ratios resulting in 6.32, 7.06, and 10.78 FR/PCR. The PC in the gear ratio maximising PPO was 120 rpm. Analysis of PC data revealed a significant decrease (P < 0.05) as the number of FR/PCR increased. PMID:8925824

  6. Landing Energy Dissipation for Manned Reentry Vehicles

    NASA Technical Reports Server (NTRS)

    Fisher, Loyd. L.

    1960-01-01

    The film shows experimental investigations to determine the landing-energy-dissipation characteristics for several types of landing gear for manned reentry vehicles. The landing vehicles are considered in two categories: those having essentially vertical-descent paths, the parachute-supported vehicles, and those having essentially horizontal paths, the lifting vehicles. The energy-dissipation devices include crushable materials such as foamed plastics and honeycomb for internal application in couch-support systems, yielding metal elements as part of the structure of capsules or as alternates for oleos in landing-gear struts, inflatable bags, braking rockets, and shaped surfaces for water impact.

  7. Getting into Gear

    ERIC Educational Resources Information Center

    Cobbs, Georgia A.; Cranor-Buck, Edith

    2011-01-01

    This article describes a particular activity, the Motorized Toy unit, which supports science, technology, engineering, and mathematics (STEM) goals and teaches students the basic concept of ratio. The unit addresses both mathematics and science standards and is part of a team-teaching activity. The unit comes from a curriculum titled A World In…

  8. Apollo 9 Lunar Module in lunar landing configuration

    NASA Technical Reports Server (NTRS)

    1969-01-01

    View of the Apollo 9 Lunar Module, in a lunar landing configuration, as photographed form the Command/Service Module on the fifth day of the Apollo 9 earth-orbital mission. The landing gear on the 'Spider' has been deployed. Lunar surface probes (sensors) extend out from the landing gear foot pads. Inside the 'Spider' were Astronauts James A. McDivitt, Apollo 9 commander; and Russell L. Schweickart, lunar module pilot.

  9. Apollo 9 Lunar Module in lunar landing configuration

    NASA Technical Reports Server (NTRS)

    1969-01-01

    View of the Apollo 9 Lunar Module, in a lunar landing configuration, as photographed form the Command/Service Module on the fifth day of the Apollo 9 earth-orbital mission. The Lunar Module 'Spider' is flying upside down in relation to the earth below. The landing gear on the 'Spider' had been deployed. Lunar surface probes (sensors) extend out from the landing gear foot pads.

  10. Expansion of epicyclic gear dynamic analysis program

    NASA Technical Reports Server (NTRS)

    Boyd, Linda Smith; Pike, James A.

    1987-01-01

    The multiple mesh/single stage dynamics program is a gear tooth analysis program which determines detailed geometry, dynamic loads, stresses, and surface damage factors. The program can analyze a variety of both epicyclic and single mesh systems with spur or helical gear teeth including internal, external, and buttress tooth forms. The modifications refine the options for the flexible carrier and flexible ring gear rim and adds three options: a floating Sun gear option; a natural frequency option; and a finite element compliance formulation for helical gear teeth. The option for a floating Sun incorporates two additional degrees of freedom at the Sun center. The natural frequency option evaluates the frequencies of planetary, star, or differential systems as well as the effect of additional springs at the Sun center and those due to a flexible carrier and/or ring gear rim. The helical tooth pair finite element calculated compliance is obtained from an automated element breakup of the helical teeth and then is used with the basic gear dynamic solution and stress postprocessing routines. The flexible carrier or ring gear rim option for planetary and star spur gear systems allows the output torque per carrier and ring gear rim segment to vary based on the dynamic response of the entire system, while the total output torque remains constant.

  11. Precision of spiral-bevel gears

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1982-01-01

    The kinematic errors in spiral bevel gear trains caused by the generation of nonconjugate surfaces, by axial displacements of the gears during assembly, and by eccentricity of the assembled gears were determined. One mathematical model corresponds to the motion of the contact ellipse across the tooth surface, (geometry I) and the other along the tooth surface (geometry II). The following results were obtained: (1) kinematic errors induced by errors of manufacture may be minimized by applying special machine settings, the original error may be reduced by order of magnitude, the procedure is most effective for geometry 2 gears, (2) when trying to adjust the bearing contact pattern between the gear teeth for geometry 1 gears, it is more desirable to shim the gear axially; for geometry II gears, shim the pinion axially; (3) the kinematic accuracy of spiral bevel drives are most sensitive to eccentricities of the gear and less sensitive to eccentricities of the pinion. The precision of mounting accuracy and manufacture are most crucial for the gear, and less so for the pinion.

  12. Precision of spiral-bevel gears

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Goldrich, R. N.; Coy, J. J.; Zaretsky, E. V.

    1983-01-01

    The kinematic errors in spiral bevel gear trains caused by the generation of nonconjugate surfaces, by axial displacements of the gears during assembly, and by eccentricity of the assembled gears were determined. One mathematical model corresponds to the motion of the contact ellipse across the tooth surface, (geometry I) and the other along the tooth surface (geometry II). The following results were obtained: (1) kinematic errors induced by errors of manufacture may be minimized by applying special machine settings, the original error may be reduced by order of magnitude, the procedure is most effective for geometry 2 gears, (2) when trying to adjust the bearing contact pattern between the gear teeth for geometry I gears, it is more desirable to shim the gear axially; for geometry II gears, shim the pinion axially; (3) the kinematic accuracy of spiral bevel drives are most sensitive to eccentricities of the gear and less sensitive to eccentricities of the pinion. The precision of mounting accuracy and manufacture are most crucial for the gear, and less so for the pinion. Previously announced in STAR as N82-30552

  13. Zero torque gear head wrench

    NASA Technical Reports Server (NTRS)

    Mcdougal, A. R.; Norman, R. M. (Inventor)

    1976-01-01

    A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed.

  14. Swimming bacteria power microscopic gears

    SciTech Connect

    Sokolov, Andrey; Apodaca, Mario M.; Grzybowski, Bartosz A.; Aranson, Igor S.

    2010-01-19

    Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be “rectified” under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears’ angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms.

  15. An international land-biosphere model benchmarking activity for the IPCC Fifth Assessment Report (AR5)

    SciTech Connect

    Hoffman, Forrest M; Randerson, James T; Thornton, Peter E; Bonan, Gordon; Erickson III, David J; Fung, Inez

    2009-12-01

    The need to capture important climate feedbacks in general circulation models (GCMs) has resulted in efforts to include atmospheric chemistry and land and ocean biogeochemistry into the next generation of production climate models, called Earth System Models (ESMs). While many terrestrial and ocean carbon models have been coupled to GCMs, recent work has shown that such models can yield a wide range of results (Friedlingstein et al., 2006). This work suggests that a more rigorous set of global offline and partially coupled experiments, along with detailed analyses of processes and comparisons with measurements, are needed. The Carbon-Land Model Intercomparison Project (C-LAMP) was designed to meet this need by providing a simulation protocol and model performance metrics based upon comparisons against best-available satellite- and ground-based measurements (Hoffman et al., 2007). Recently, a similar effort in Europe, called the International Land Model Benchmark (ILAMB) Project, was begun to assess the performance of European land surface models. These two projects will now serve as prototypes for a proposed international land-biosphere model benchmarking activity for those models participating in the IPCC Fifth Assessment Report (AR5). Initially used for model validation for terrestrial biogeochemistry models in the NCAR Community Land Model (CLM), C-LAMP incorporates a simulation protocol for both offline and partially coupled simulations using a prescribed historical trajectory of atmospheric CO2 concentrations. Models are confronted with data through comparisons against AmeriFlux site measurements, MODIS satellite observations, NOAA Globalview flask records, TRANSCOM inversions, and Free Air CO2 Enrichment (FACE) site measurements. Both sets of experiments have been performed using two different terrestrial biogeochemistry modules coupled to the CLM version 3 in the Community Climate System Model version 3 (CCSM3): the CASA model of Fung, et al., and the carbon

  16. An International Land-Biosphere Model Benchmarking Activity for the IPCC Fifth Assessment Report (AR5)

    NASA Astrophysics Data System (ADS)

    Hoffman, F. M.; Randerson, J. T.; Thornton, P. E.; Bonan, G. B.; Brooks, B. J.; Erickson, D. J.; Fung, I.

    2009-12-01

    The need to capture important climate feedbacks in general circulation models (GCMs) has resulted in efforts to include atmospheric chemistry and land and ocean biogeochemistry into the next generation of production climate models, called Earth System Models (ESMs). While many terrestrial and ocean carbon models have been coupled to GCMs, recent work has shown that such models can yield a wide range of results (Friedlingstein et al., 2006). This work suggests that a more rigorous set of global offline and partially coupled experiments, along with detailed analyses of processes and comparisons with measurements, are needed. The Carbon-Land Model Intercomparison Project (C-LAMP) was designed to meet this need by providing a simulation protocol and model performance metrics based upon comparisons against best-available satellite- and ground-based measurements (Hoffman et al., 2007). Recently, a similar effort in Europe, called the International Land Model Benchmark (ILAMB) Project, was begun to assess the performance of European land surface models. These two projects will now serve as prototypes for a proposed international land-biosphere model benchmarking activity for those models participating in the IPCC Fifth Assessment Report (AR5). Initially used for model validation for terrestrial biogeochemistry models in the NCAR Community Land Model (CLM), C-LAMP incorporates a simulation protocol for both offline and partially coupled simulations using a prescribed historical trajectory of atmospheric CO2 concentrations. Models are confronted with data through comparisons against AmeriFlux site measurements, MODIS satellite observations, NOAA Globalview flask records, TRANSCOM inversions, and Free Air CO2 Enrichment (FACE) site measurements. Both sets of experiments have been performed using two different terrestrial biogeochemistry modules coupled to the CLM version 3 in the Community Climate System Model version 3 (CCSM3): the CASA model of Fung, et al., and the carbon

  17. Knee and Hip Joint Kinematics Predict Quadriceps and Hamstrings Neuromuscular Activation Patterns in Drop Jump Landings

    PubMed Central

    Malfait, Bart; Dingenen, Bart; Smeets, Annemie; Staes, Filip; Pataky, Todd; Robinson, Mark A.; Vanrenterghem, Jos; Verschueren, Sabine

    2016-01-01

    Purpose The purpose was to assess if variation in sagittal plane landing kinematics is associated with variation in neuromuscular activation patterns of the quadriceps-hamstrings muscle groups during drop vertical jumps (DVJ). Methods Fifty female athletes performed three DVJ. The relationship between peak knee and hip flexion angles and the amplitude of four EMG vectors was investigated with trajectory-level canonical correlation analyses over the entire time period of the landing phase. EMG vectors consisted of the {vastus medialis(VM),vastus lateralis(VL)}, {vastus medialis(VM),hamstring medialis(HM)}, {hamstring medialis(HM),hamstring lateralis(HL)} and the {vastus lateralis(VL),hamstring lateralis(HL)}. To estimate the contribution of each individual muscle, linear regressions were also conducted using one-dimensional statistical parametric mapping. Results The peak knee flexion angle was significantly positively associated with the amplitudes of the {VM,HM} and {HM,HL} during the preparatory and initial contact phase and with the {VL,HL} vector during the peak loading phase (p<0.05). Small peak knee flexion angles were significantly associated with higher HM amplitudes during the preparatory and initial contact phase (p<0.001). The amplitudes of the {VM,VL} and {VL,HL} were significantly positively associated with the peak hip flexion angle during the peak loading phase (p<0.05). Small peak hip flexion angles were significantly associated with higher VL amplitudes during the peak loading phase (p = 0.001). Higher external knee abduction and flexion moments were found in participants landing with less flexed knee and hip joints (p<0.001). Conclusion This study demonstrated clear associations between neuromuscular activation patterns and landing kinematics in the sagittal plane during specific parts of the landing. These findings have indicated that an erect landing pattern, characterized by less hip and knee flexion, was significantly associated with an

  18. Bacteria turn a tiny gear

    SciTech Connect

    2009-01-01

    Thousands of tiny Bacillus subtillis bacteria turn a single gear, just 380 microns across. (A human hair is about 100 microns across.) The method could be used to create micro-machines. Argonne National Laboratory scientist Igor Aronson pioneered this technique. Read more at the New York Times: http://ow.ly/ODfI or at Argonne: http://ow.ly/ODfa Video courtesy Igor Aronson.

  19. Output gear of automatic transmission

    SciTech Connect

    Ideta, Y.; Miida, S.

    1986-12-16

    An automatic transmission is described for a front engine, front wheel drive vehicle, comprising: a torque converter; a main power train comprising a rotatory terminal member, the main power train being connected with the torque converter for transmitting a driving torque from the torque converter to the terminal member; housing means enclosing the main power train, the housing means having a cylindrical bore and at least one oil feed passage opening in a cylindrical surface of the bore, and an output gear rotatably supported by the housing means and connected detachably with the terminal member of the main power train for transmitting the driving torque from the main power train to front wheels of the vehicle. The main power train is placed between the torque converter and the output gear, the output gear having a hub which is splined detachably to the terminal member, and which is fitting in the bore of the housing means in such a manner that the hub can rotate in the bore. The hub has an annular groove formed on an outer cylindrical surface of the hub, the output gear being formed with lubricating means extending from the annular groove for conveying oil from the annular groove, the oil feed passage of the housing means opening into the annular groove for supplying oil into the lubricating means through the annular groove. The annular groove has sufficient depth and width within a range permitted by a strength of the hub to prevent a shortage of the oil supply through the annular groove to the lubricating means due to a centrifugal force of the oil rotating in the annular groove together with walls of the annular groove.

  20. 49 CFR 230.92 - Draw gear and draft systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Draw gear and draft systems. 230.92 Section 230.92... Tenders Draw Gear and Draft Systems § 230.92 Draw gear and draft systems. Couplers, draft gear and... condition for service. Driving Gear...

  1. 50 CFR 660.219 - Fixed gear identification and marking.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Fixed gear identification and marking... West Coast Groundfish-Limited Entry Fixed Gear Fisheries § 660.219 Fixed gear identification and marking. (a) Gear identification. (1) Limited entry fixed gear (longline, trap or pot) must be marked...

  2. 50 CFR 660.219 - Fixed gear identification and marking.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Fixed gear identification and marking... West Coast Groundfish-Limited Entry Fixed Gear Fisheries § 660.219 Fixed gear identification and marking. (a) Gear identification. (1) Limited entry fixed gear (longline, trap or pot) must be marked...

  3. 50 CFR 622.375 - Authorized and unauthorized gear.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Authorized and unauthorized gear. 622.375... unauthorized gear. (a) Authorized gear. Subject to the prohibitions on gear/methods specified in § 622.9, the following are the only fishing gears that may be used in the Gulf, Mid-Atlantic, and South Atlantic EEZ...

  4. 49 CFR 230.92 - Draw gear and draft systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Draw gear and draft systems. 230.92 Section 230.92... Tenders Draw Gear and Draft Systems § 230.92 Draw gear and draft systems. Couplers, draft gear and... condition for service. Driving Gear...

  5. 49 CFR 230.92 - Draw gear and draft systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Draw gear and draft systems. 230.92 Section 230.92... Tenders Draw Gear and Draft Systems § 230.92 Draw gear and draft systems. Couplers, draft gear and... condition for service. Driving Gear...

  6. 49 CFR 230.92 - Draw gear and draft systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Draw gear and draft systems. 230.92 Section 230.92... Tenders Draw Gear and Draft Systems § 230.92 Draw gear and draft systems. Couplers, draft gear and... condition for service. Driving Gear...

  7. 49 CFR 230.92 - Draw gear and draft systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Draw gear and draft systems. 230.92 Section 230.92... Tenders Draw Gear and Draft Systems § 230.92 Draw gear and draft systems. Couplers, draft gear and... condition for service. Driving Gear...

  8. 50 CFR 648.51 - Gear and crew restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Gear and crew restrictions. 648.51... Measures for the Atlantic Sea Scallop Fishery § 648.51 Gear and crew restrictions. (a) Trawl vessel gear... long axis of the net. (3) Chafing gear and other gear obstructions—(i) Net obstruction or...

  9. 50 CFR 660.219 - Fixed gear identification and marking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Fixed gear identification and marking... West Coast Groundfish-Limited Entry Fixed Gear Fisheries § 660.219 Fixed gear identification and marking. (a) Gear identification. (1) Limited entry fixed gear (longline, trap or pot) must be marked...

  10. 50 CFR 697.23 - Restricted gear areas.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Measures § 697.23 Restricted gear areas. (a) Resolution of lobster gear conflicts with fisheries managed... all mobile gear is on board the vessel while inside the area. (ii) Lobster trap gear. From June 16 through September 30 of each fishing year, no fishing vessel with lobster trap gear or person on a...

  11. 50 CFR 697.23 - Restricted gear areas.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Measures § 697.23 Restricted gear areas. (a) Resolution of lobster gear conflicts with fisheries managed... all mobile gear is on board the vessel while inside the area. (ii) Lobster trap gear. From June 16 through September 30 of each fishing year, no fishing vessel with lobster trap gear or person on a...

  12. 50 CFR 697.23 - Restricted gear areas.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Measures § 697.23 Restricted gear areas. (a) Resolution of lobster gear conflicts with fisheries managed... all mobile gear is on board the vessel while inside the area. (ii) Lobster trap gear. From June 16 through September 30 of each fishing year, no fishing vessel with lobster trap gear or person on a...

  13. 50 CFR 697.23 - Restricted gear areas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Measures § 697.23 Restricted gear areas. (a) Resolution of lobster gear conflicts with fisheries managed... all mobile gear is on board the vessel while inside the area. (ii) Lobster trap gear. From June 16 through September 30 of each fishing year, no fishing vessel with lobster trap gear or person on a...

  14. 50 CFR 697.23 - Restricted gear areas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Measures § 697.23 Restricted gear areas. (a) Resolution of lobster gear conflicts with fisheries managed... all mobile gear is on board the vessel while inside the area. (ii) Lobster trap gear. From June 16 through September 30 of each fishing year, no fishing vessel with lobster trap gear or person on a...

  15. 29 CFR 1919.19 - Gear requiring welding.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Gear requiring welding. 1919.19 Section 1919.19 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels' Cargo Gear § 1919.19 Gear requiring welding. Chains or other gear which have been lengthened, altered or repaired by welding shall be properly...

  16. 29 CFR 1919.19 - Gear requiring welding.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Gear requiring welding. 1919.19 Section 1919.19 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels' Cargo Gear § 1919.19 Gear requiring welding. Chains or other gear which have been lengthened, altered or repaired by welding shall be properly...

  17. 29 CFR 1919.19 - Gear requiring welding.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Gear requiring welding. 1919.19 Section 1919.19 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels' Cargo Gear § 1919.19 Gear requiring welding. Chains or other gear which have been lengthened, altered or repaired by welding shall be properly...

  18. 29 CFR 1919.19 - Gear requiring welding.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Gear requiring welding. 1919.19 Section 1919.19 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels' Cargo Gear § 1919.19 Gear requiring welding. Chains or other gear which have been lengthened, altered or repaired by welding shall be properly...

  19. 29 CFR 1919.19 - Gear requiring welding.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Gear requiring welding. 1919.19 Section 1919.19 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels' Cargo Gear § 1919.19 Gear requiring welding. Chains or other gear which have been lengthened, altered or repaired by welding shall be properly...

  20. Performance investigation of a novel pseudoelastic SMA mesh washer gear wheel with micro-jitter attenuation capability

    NASA Astrophysics Data System (ADS)

    Kwon, Seong-Cheol; Jeon, Su-Hyeon; Oh, Hyun-Ung

    2016-05-01

    A stepper-actuated mechanism, such as a gimbal type antenna, is a major source of micro-jitters that affect the image quality of a high-resolution observation satellite. Attenuating micro-jitter disturbances induced by a stepper motor activation is one method of enhancing image quality of an observation satellite. In this study, we propose a novel gear with micro-jitter attenuation capability for stepper-actuated mechanism. This can be achieved by implementing a pseudoelastic shape memory alloy mesh washer on the gear wheel. This application makes it possible to achieve the gear with lower torsional stiffness and higher damping in the torsional direction of the gear, whose characteristics will assist in resolving the micro-jitter attenuation issues of a gear. The effectiveness of the gear proposed in this study was demonstrated by numerical simulation and jitter measurement tests using the gimbal type antenna mechanism actuated by the stepper motor.

  1. Effects of various midsole densities of basketball shoes on impact attenuation during landing activities.

    PubMed

    Zhang, Songning; Clowers, Kurt; Kohstall, Charles; Yu, Yeon-Joo

    2005-02-01

    The purpose of this study was to examine effects of shoe midsole densities and mechanical demands (landing heights) on impact shock attenuation and lower extremity biomechanics during a landing activity. Nine healthy male college athletes performed 5 trials of step-off landing in each of 9 test conditions, i.e., a combination of landings in shoes of 3 midsole densities (soft, normal, hard) from each of 3 landing potential energy (PE) levels (low, median, high). Ground reaction forces (GRF), accelerations (ACC) of the tibia and forehead, and sagittal kinematic data were sampled simultaneously. A 3 x 3 two-way (surface x height) repeated-measures analysis of variance (ANOVA) was performed on selected kinematic, ACC, and GRF variables; a 3 x 3 x 3 three-way (surface x height x joint) ANOVA was performed on variables related to eccentric muscular work. The GRF results showed that the forefoot peak GRF in the normal and hard midsoles was significantly greater than the soft midsole at the low and median PEs. Rearfoot peak GRF was significantly greater for the hard midsole than for the soft and normal midsoles at the median and high PEs, respectively. The peak head and tibia peak ACC were also attenuated in similar fashion. Kinematic variables did not vary significantly across different midsoles, nor did energy absorbed through lower extremity extensors in response to the increased shoe stiffness. Knee joint extensors were shown to be dominant in attenuating the forefoot impact force across the landing heights. The results showed limited evidence of impact-attenuating benefits of the soft midsole in the basketball shoes.

  2. Decree No. 922 on land use and exercise of agricultural activities, 19 May 1989.

    PubMed

    1989-01-01

    The Bulgarian Decree 922, May 19, 1989, regulates land use and the exercise of agricultural activities. It stipulates in general that agricultural activities and land use will be based on the principles of company organization, ensuring the unity and indivisibility of socialist property and the variety of forms of land use and management, using collective farms and companies. Citizens may engage in agricultural activities without having a registered company; users of farmland must protect the environment; observe veterinary, plant protection, and sanitary hygiene regulations; and protect and improve soil fertility. Farms and other companies will carry out their activities under equal conditions, may sell their commodities may set up an association for the protection of their economic and social interests, and may establish agricultural stock exchanges and other cooperatives in accordance with stipulated procedures. Individual farms include an individual farmer or several farmers. Farmers may rent or purchase agricultural equipment without restriction as to model, capacity, or other features. Limitations apply on the number of workers employed on a nonseasonal basis. Farmers may form associations for specified purposes. Taxation is based on the general income tax law. Piece rate is a form of organization and payment of labor in agriculture; written agreements are required regarding wages, quality, quantity, deadlines, and supplies furnished. Lease contracts must be in writing, be registered by the municipal people's council at the location of the project, and contain specified information.

  3. Crowd-Sourcing Management Activity Data to Drive GHG Emission Inventories in the Land Use Sector

    NASA Astrophysics Data System (ADS)

    Paustian, K.; Herrick, J.

    2015-12-01

    Greenhouse gas (GHG) emissions from the land use sector constitute the largest source category for many countries in Africa. Enhancing C sequestration and reducing GHG emissions on managed lands in Africa has to potential to attract C financing to support adoption of more sustainable land management practices that, in addition to GHG mitigation, can provide co-benefits of more productive and climate-resilient agroecosystems. However, robust systems to measure and monitor C sequestration/GHG reductions are currently a significant barrier to attracting more C financing to land use-related mitigation efforts.Anthropogenic GHG emissions are driven by a variety of environmental factors, including climate and soil attributes, as well as human-activities in the form of land use and management practices. GHG emission inventories typically use empirical or process-based models of emission rates that are driven by environmental and management variables. While a lack of field-based flux and C stock measurements are a limiting factor for GHG estimation, we argue that an even greater limitation may be availabiity of data on the management activities that influence flux rates, particularly in developing countries in Africa. In most developed countries there is a well-developed infrastructure of agricultural statistics and practice surveys that can be used to drive model-based GHG emission estimations. However, this infrastructure is largely lacking in developing countries in Africa. While some activity data (e.g. land cover change) can be derived from remote sensing, many key data (e.g., N fertilizer practices, residue management, manuring) require input from the farmers themselves. The explosive growth in cellular technology, even in many of the poorest parts of Africa, suggests the potential for a new crowd-sourcing approach and direct engagement with farmers to 'leap-frog' the land resource information model of developed countries. Among the many benefits of this approach

  4. Automatic transmission's Ravigneaux type planetary gear train having two ring gears

    SciTech Connect

    Hiraiwa, K.

    1989-02-07

    A planetary gear system is described comprising: a stationary member; input means for receiving a driving torque; an output shaft; a compound planetary gear train; a clutch group including a first clutch disposed between the input means and the first sun gear for connection and disconnection therebetween, a second clutch disposed between the input means and the second sun gear for connection and disconnection therebetween, and a third clutch disposed between the input means and the pinion carrier for connection and disconnection therebetween; and a holding device group including a first holding device disposed between the first sun gear and the stationary member for holding the first sun gear, a second holding device disposed between the pinion carrier and the stationary member for holding the pinion carrier, and a third holding device disposed between the second ring gear and the stationary member for holding the second ring gear.

  5. Lubrication and cooling for high speed gears

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.

    1985-01-01

    The problems and failures occurring with the operation of high speed gears are discussed. The gearing losses associated with high speed gearing such as tooth mesh friction, bearing friction, churning, and windage are discussed with various ways shown to help reduce these losses and thereby improve efficiency. Several different methods of oil jet lubrication for high speed gearing are given such as into mesh, out of mesh, and radial jet lubrication. The experiments and analytical results for the various methods of oil jet lubrication are shown with the strengths and weaknesses of each method discussed. The analytical and experimental results of gear lubrication and cooling at various test conditions are presented. These results show the very definite need of improved methods of gear cooling at high speed and high load conditions.

  6. Topological and parametric optimization of gear trains

    NASA Astrophysics Data System (ADS)

    Swantner, Albert; Campbell, Matthew I.

    2012-11-01

    A method for automating the design of gear trains comprised of simple, compound, bevel and worm is described. The search process combines topological changes, discrete variable choices and continuous variable optimization. By combing best-first search, implicit enumeration, automated optimization invocation and gradient-based optimization, a near guarantee of the optimal solution can be made. While the combination of methods is specific to gear trains, there are aspects of the work that make it amenable to other engineering design problems. In addition, the topological and discrete modifications to the candidate solutions are specific to gear trains, but the graph grammar methodology that is adopted has been tailored to other problems. This article presents details on the rules that generate feasible gear trains, the evaluation routines used in determining the objective functions and constraints, and the interaction among the three search methods. Resulting gear trains are presented for a variety of gear problems.

  7. 50 CFR 660.230 - Fixed gear fishery-management measures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... sablefish landing permitted for that week. The trip limit for black rockfish caught with hook-and-line gear..., shortbelly rockfish, black rockfish, blue rockfish, minor nearshore rockfish, minor shelf rockfish, minor..., starry flounder, English sole, other flatfish, lingcod, sablefish, Pacific cod, spiny dogfish, other...

  8. Tool Gear: Infrastructure for Parallel Tools

    SciTech Connect

    May, J; Gyllenhaal, J

    2003-04-17

    Tool Gear is a software infrastructure for developing performance analysis and other tools. Unlike existing integrated toolkits, which focus on providing a suite of capabilities, Tool Gear is designed to help tool developers create new tools quickly. It combines dynamic instrumentation capabilities with an efficient database and a sophisticated and extensible graphical user interface. This paper describes the design of Tool Gear and presents examples of tools that have been built with it.

  9. Higher Landing Accuracy in Expert Pilots is Associated with Lower Activity in the Caudate Nucleus

    PubMed Central

    Adamson, Maheen M.; Taylor, Joy L.; Heraldez, Daniel; Khorasani, Allen; Noda, Art; Hernandez, Beatriz; Yesavage, Jerome A.

    2014-01-01

    The most common lethal accidents in General Aviation are caused by improperly executed landing approaches in which a pilot descends below the minimum safe altitude without proper visual references. To understand how expertise might reduce such erroneous decision-making, we examined relevant neural processes in pilots performing a simulated landing approach inside a functional MRI scanner. Pilots (aged 20–66) were asked to “fly” a series of simulated “cockpit view” instrument landing scenarios in an MRI scanner. The scenarios were either high risk (heavy fog–legally unsafe to land) or low risk (medium fog–legally safe to land). Pilots with one of two levels of expertise participated: Moderate Expertise (Instrument Flight Rules pilots, n = 8) or High Expertise (Certified Instrument Flight Instructors or Air-Transport Pilots, n = 12). High Expertise pilots were more accurate than Moderate Expertise pilots in making a “land” versus “do not land” decision (CFII: d′ = 3.62±2.52; IFR: d′ = 0.98±1.04; p<.01). Brain activity in bilateral caudate nucleus was examined for main effects of expertise during a “land” versus “do not land” decision with the no-decision control condition modeled as baseline. In making landing decisions, High Expertise pilots showed lower activation in the bilateral caudate nucleus (0.97±0.80) compared to Moderate Expertise pilots (1.91±1.16) (p<.05). These findings provide evidence for increased “neural efficiency” in High Expertise pilots relative to Moderate Expertise pilots. During an instrument approach the pilot is engaged in detailed examination of flight instruments while monitoring certain visual references for making landing decisions. The caudate nucleus regulates saccade eye control of gaze, the brain area where the “expertise” effect was observed. These data provide evidence that performing “real world” aviation tasks in an fMRI provide objective data regarding the

  10. Gear train housing of an engine

    SciTech Connect

    Sweetland, R.D.; Hager, F.M.

    1989-12-12

    This patent describes a gear train housing of a engine of the type having an internal gear space located within housing parts, which includes at least one housing body part and at least one housing cover part. The housing parts being joined together at opposed vertical oriented edge faces, with a gasket seal therebetween, by bolts passing through the housing parts and bosses of the housing body part formed at the edge face thereof so as to be situated projecting into the gear space. Wherein the gear space is defined by internal wall surfaces of the housing parts which include upwardly facing sloping wall surfaces along which some of the bosses are located.

  11. Design of spur gears for improved efficiency

    NASA Technical Reports Server (NTRS)

    Anderson, N. E.; Loewenthal, S. H.

    1981-01-01

    A method to calculate spur gear system power loss for a wide range of gear geometries and operating conditions is used to determine design requirements for an efficient gearset. The effects of spur gear size, pitch, ratio, pitch-line-velocity and load on efficiency are shown. A design example is given to illustrate how the method is to be applied. In general, peak efficiencies were found to be greater for larger diameter and fine pitched gears and tare (no-load) losses were found to be significant.

  12. Effects of gear crack propagation paths on vibration responses of the perforated gear system

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Pang, Xu; Zeng, Jin; Wang, Qibin; Wen, Bangchun

    2015-10-01

    This paper investigates the dynamic behaviors of a perforated gear system considering effects of the gear crack propagation paths and this study focuses on the effects of a crack propagating through the rim on the time-varying mesh stiffness (TVMS) and vibration responses. Considering the effects of the extended tooth contact, a finite element (FE) model of a gear pair is established based on ANSYS software. TVMS of the perforated gear with crack propagating through tooth and rim are calculated by using the FE model. Furthermore, a lumped mass model is adopted to investigate the vibration responses of the perforated gear system. The results show that there exist three periods related to slots of the gear body in a rotating period of the perforated gear. Gear cracks propagating through tooth and rim both reduce the gear body stiffness and lead to reduction of TVMS besides the crack tooth contact moment, and the TVMS weakening for the former is less than that for the latter. Moreover, the results also show that the gear crack propagating through the rim (CPR) has a greater effect on vibration responses than the gear crack propagating through the tooth (CPT) under the same crack level. Vibration level increases with the increasing crack depth, especially for the gear with CPR.

  13. Optimum weight design of functionally graded material gears

    NASA Astrophysics Data System (ADS)

    Jing, Shikai; Zhang, He; Zhou, Jingtao; Song, Guohua

    2015-11-01

    Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials (FGMs) to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization (GDO) method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.

  14. STS-40 Columbia, OV-102, lands on concrete runway 22 at EAFB, California

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-40 Columbia's, Orbiter Vehicle (OV) 102's, main landing gear (MLG) touches down on concrete runway 22 at Edwards Air Force Base (EAFB), California at 8:29:11 am (Pacific Daylight Time (PDT)). OV-102's port side is captured in this profile view as its nose landing gear (NLG) glides above the runway before touch down and wheel stop.

  15. STS-40 Columbia, OV-102, lands on concrete runway 22 at EAFB, California

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-40 Columbia's, Orbiter Vehicle (OV) 102's, main landing gear (MLG) touches down on concrete runway 22 at Edwards Air Force Base (EAFB), California at 8:29:11 am (Pacific Daylight Time (PDT)). OV-102's starboard side is captured in this profile view as its nose landing gear (NLG) glides above the runway before touch down and wheel stop.

  16. STS-29 Discovery, OV-103, lands on Edwards AFB concrete runway 22

    NASA Technical Reports Server (NTRS)

    1989-01-01

    STS-29 Discovery, Orbiter Vehicle (OV) 103, main landing gear (MLG) touches down at a speed of approximately 205 knots (235 miles per hour) on concrete runway 22 at Edwards Air Force Base (AFB), California. Nose landing gear (NLG) is deployed and rides above runway surface prior touchdown. Mojave desert scrub brush appears in the foreground with mountain range appearing in the background.

  17. PARK-IT! Elementary School Land Laboratories in Toledo City Parks. Curriculum Activity Guide, Grades K-1.

    ERIC Educational Resources Information Center

    DuFour, Marilyn Berry; Courter, Linda Kothera; Garvin, Dennis M.

    The project PARK-IT! represents a unique partnership between a public elementary school and a city park in which students and teachers utilize a small naturalized area of the park as a Land Laboratory, and in return become its stewards. The project also includes this curriculum activity guide which can assist teachers in using the Land Lab with…

  18. PARK-IT! Elementary School Land Laboratories in Toledo City Parks. Curriculum Activity Guide, Grades 2-3.

    ERIC Educational Resources Information Center

    DuFour, Marilyn Berry; Courter, Linda Kothera; Garvin, Dennis M.

    The project PARK-IT! represents a unique partnership between a public elementary school and a city park in which students and teachers utilize a small naturalized area of the park as a Land Laboratory, and in return become its stewards. The project also includes this curriculum activity guide which can assist teachers in using the Land Lab with…

  19. PARK-IT! Elementary School Land Laboratories in Toledo City Parks. Curriculum Activity Guide, Grades 4-6.

    ERIC Educational Resources Information Center

    DuFour, Marilyn Berry; Courter, Linda Kothera; Garvin, Dennis M.

    The project PARK-IT! represents a unique partnership between a public elementary school and a city park in which students and teachers utilize a small naturalized area of the park as a Land Laboratory, and in return become its stewards. The project also includes this curriculum activity guide which can assist teachers in using the Land Lab with…

  20. New Gear Transmission Error Measurement System Designed

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.

    2001-01-01

    The prime source of vibration and noise in a gear system is the transmission error between the meshing gears. Transmission error is caused by manufacturing inaccuracy, mounting errors, and elastic deflections under load. Gear designers often attempt to compensate for transmission error by modifying gear teeth. This is done traditionally by a rough "rule of thumb" or more recently under the guidance of an analytical code. In order for a designer to have confidence in a code, the code must be validated through experiment. NASA Glenn Research Center contracted with the Design Unit of the University of Newcastle in England for a system to measure the transmission error of spur and helical test gears in the NASA Gear Noise Rig. The new system measures transmission error optically by means of light beams directed by lenses and prisms through gratings mounted on the gear shafts. The amount of light that passes through both gratings is directly proportional to the transmission error of the gears. A photodetector circuit converts the light to an analog electrical signal. To increase accuracy and reduce "noise" due to transverse vibration, there are parallel light paths at the top and bottom of the gears. The two signals are subtracted via differential amplifiers in the electronics package. The output of the system is 40 mV/mm, giving a resolution in the time domain of better than 0.1 mm, and discrimination in the frequency domain of better than 0.01 mm. The new system will be used to validate gear analytical codes and to investigate mechanisms that produce vibration and noise in parallel axis gears.