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Sample records for 500-hp helicopter transmission

  1. Design of an advanced 500-HP helicopter transmission

    NASA Technical Reports Server (NTRS)

    Braddock, C. E.

    1982-01-01

    A 500-hp Advanced Technology Demonstrator helicopter transmission was designed by an American aerospace company under a NASA contract. The project was mainly concerned with designing a 500-hp version of the OH-58C 317-hp transmission which would have the capabilities for a long, quiet life at a minimum increase in cost, weight, and space, which usually increase along with power increases. This objective was accomplished by implementing advanced technology which has been developed during the last decade and by making improvements dictated by field experience. The improvements are related to bearings made of cleaner gear steels, spiral bevel gears made of cleaner gear steels, high contact ratio spur gear teeth in the planetary which will reduce noise level and increase gear life, and modifications concerning the sun gear.

  2. Lubricant Effects on Efficiency of a Helicopter Transmission.

    DTIC Science & Technology

    1982-01-01

    Research Cen- ter’s 500 hp torque regenerative helicopter transmission test stand. The test transmission was the 01158 helicopter main transmission...cooling systema. This effect adds to increase the payload capacity of the helicopter. The total power loss in a helicopter transmision is a function...friction between Sear teeth . Martin (rof 3) concentrates on the problem of calcmlatiui the losses in the tooth contact. Anderson and Loeventhel (ref 4

  3. Lubricant Effects on Efficiency of a Helicopter Transmission

    NASA Technical Reports Server (NTRS)

    Mitchell, A. M.; Coy, J. J.

    1982-01-01

    Eleven different lubricants were used in efficiency tests conducted on the OH-58A helicopter main transmission using the NASA Lewis Research Center's 500 hp torque regenerative helicopter transmission test stand. Tests were run at oil-in temperatures of 355 K and 372 K. The efficiency was calculated from a heat balance on the water running through an oil to water heat exchanger which the transmission was heavily insulated. Results show an efficiency range from 98.3% to 98.8% which is a 50% variation relative to the losses associated with the maximum efficiency measured. For a given lubricant, the efficiency increased as temperature increased and viscosity decreased. There were two exceptions which could not be explained. Between lubricants, efficiency was not correlated with viscosity. There were relatively large variations in efficiency with the different lubricants whose viscosity generally fell in the 5 to 7 centistoke range. The lubricants had no significant effect on the vibration signature of the transmission.

  4. Effect of advanced component technology on helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Townsend, Dennis P.

    1989-01-01

    Experimental tests were performed on the NASA/Bell Helicopter Textron (BHT) 500 hp advanced technology transmission (ATT) at the NASA Lewis Research Center. The ATT was a retrofit of the OH-58C helicopter 236 kW (317 hp) main rotor transmission, upgraded to 373 kW (500 hp), with a design goal of retaining long life with a minimum increase in cost, weight, and size. Vibration, strain, efficiency, deflection, and temperature experiments were performed and the results were compared to previous experiments on the OH-58A, OH-58C, and UH-60A transmissions. The high-contact-ratio gears and the cantilevered-mounted, flexible ring gear of the ATT reduced vibration compared to that of the OH-58C. The ATT flexible ring gear improved planetary load sharing compared to that of the rigid ring gear of the UH-60A transmission. The ATT mechanical efficiency was lower than that of the OH-58A transmission, probably due to the high-contact-ratio planetary gears.

  5. Assessment of worm gearing for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Chaiko, Lev

    1990-01-01

    A high-efficiency hydrostatic worm gear drive for helicopter transmissions is assessed. The example given is for a large cargo helicopter with three 4000-kW engines and transmission reduction ratio of 110. Also contained are: an efficiency calculation, a description of the test stand for evaluating the feasibility of worm gear hydrostatic mesh, a weight calculation, and a comparison with conventional helicopter transmissions of the same power and transmission reduction ratio.

  6. NASA helicopter transmission system technology program

    NASA Technical Reports Server (NTRS)

    Zaretsky, E. V.

    1983-01-01

    The purpose of the NASA Helicopter Transmission System Technology Program is to improve specific mechanical components and the technology for combining these into advanced drive systems to make helicopters more viable and cost competitive for commerical applications. The history, goals, and elements of the program are discussed.

  7. Low-noise, high-strength, spiral-bevel gears for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Handschuh, Robert F.; Henry, Zachary S.; Litvin, Faydor L.

    1993-01-01

    Improvements in spiral-bevel gear design were investigated to support the Army/NASA Advanced Rotorcraft Transmission program. Program objectives were to reduce weight by 25 percent, reduce noise by 10 dB, and increase life to 5000 hr mean-time-between-removal. To help meet these goals, advanced-design spiral-bevel gears were tested in an OH-58D helicopter transmission using the NASA 500-hp Helicopter Transmission Test Stand. Three different gear designs tested included: (1) the current design of the OH-58D transmission except gear material X-53 instead of AISI 9310; (2) a higher-strength design the same as the current but with a full fillet radius to reduce gear tooth bending stress (and thus, weight); and (3) a lower-noise design the same as the high-strength but with modified tooth geometry to reduce transmission error and noise. Noise, vibration, and tooth strain tests were performed and significant gear stress and noise reductions were achieved.

  8. Evaluation of an oil-debris monitoring device for use in helicopter transmissions

    NASA Astrophysics Data System (ADS)

    Lewicki, David G.; Blanchette, Donald M.; Biron, Gilles

    1992-08-01

    Experimental tests were performed on an OH-58A helicopter main-rotor transmission to evaluate an oil-debris monitoring device (ODMD). The tests were performed in the NASA 500-hp Helicopter Transmission Test Stand. Five endurance tests were run as part of a U.S. Navy/NASA/Army advanced lubricants program. The tests were run at 100 percent design speed, 117-percent design torque, and 121 C (250 F) oil inlet temperature. Each test lasted between 29 and 122 hr. The oils that were used conformed to MIL-L-23699 and DOD-L-85734 specifications. One test produced a massive sun-gear fatigue failure; another test produced a small spall on one sun-gear tooth; and a third test produced a catastrophic planet-bearing cage failure. The ODMD results were compared with oil spectroscopy results. The capability of the ODMD to detect transmission component failures was not demonstrated. Two of the five tests produced large amounts of debris. For these two tests, two separate ODMD sensors failed, possibly because of prolonged exposure to relatively high oil temperatures. One test produced a small amount of debris and was not detected by the ODMD or by oil spectroscopy. In general, the ODMD results matched the oil spectroscopy results. The ODMD results were extremely sensitive to oil temperature and flow rate.

  9. Evaluation of an oil-debris monitoring device for use in helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Blanchette, Donald M.; Biron, Gilles

    1992-01-01

    Experimental tests were performed on an OH-58A helicopter main-rotor transmission to evaluate an oil-debris monitoring device (ODMD). The tests were performed in the NASA 500-hp Helicopter Transmission Test Stand. Five endurance tests were run as part of a U.S. Navy/NASA/Army advanced lubricants program. The tests were run at 100 percent design speed, 117-percent design torque, and 121 C (250 F) oil inlet temperature. Each test lasted between 29 and 122 hr. The oils that were used conformed to MIL-L-23699 and DOD-L-85734 specifications. One test produced a massive sun-gear fatigue failure; another test produced a small spall on one sun-gear tooth; and a third test produced a catastrophic planet-bearing cage failure. The ODMD results were compared with oil spectroscopy results. The capability of the ODMD to detect transmission component failures was not demonstrated. Two of the five tests produced large amounts of debris. For these two tests, two separate ODMD sensors failed, possibly because of prolonged exposure to relatively high oil temperatures. One test produced a small amount of debris and was not detected by the ODMD or by oil spectroscopy. In general, the ODMD results matched the oil spectroscopy results. The ODMD results were extremely sensitive to oil temperature and flow rate.

  10. Further Study Of Face Gears For Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Wang, J. C.; Bossler, R. B., Jr.; Chen, Y. J. D.; Heath, G.; Lewicki, D. G.

    1995-01-01

    Document describes theoretical, computational, and experimental studies of feasibility of proposed lightweight, split-torque helicopter transmissions based on face gears. Majority of work also described in prior document "Face Gears for Helicopter Transmissions" (LEW-15840).

  11. Review of the transmissions of the Soviet helicopters

    NASA Technical Reports Server (NTRS)

    Chaiko, Lev I.

    1990-01-01

    A review of the following aspects of Soviet helicopter transmissions is presented: transmitted power, weight, reduction ratio, RPM, design configuration, comparison of different type of manufacturing methods, and a description of the materials and technologies applied to critical transmission components. Included are mechanical diagrams of the gearboxes of the Soviet helicopters and test stands for testing gearbox and main shaft. The quality of Soviet helicopter transmissions and their Western counterparts are assessed and compared.

  12. Development of helicopter transmission seals, task 2

    NASA Technical Reports Server (NTRS)

    Hayden, T. S.; Keller, C. H., Jr.

    1973-01-01

    High speed helicopter transmission seal concepts were designed, fabricated and tested. The concepts were a dual element split ring seal and a circumferential seal. The tests were performed in a rig using an actual input quill assembly. The test conditions were selected to simulate transmission operation and were 230 F oil temperature, and a sliding speed of 9400 ft/min. The split ring seal exhibited gross leakage and was considered unsatisfactory, while the circumferential seal leakage was less than 1 c.c./hour; this leakage is within acceptable limits. The circumferential seal wear was only to .0005 inches during a 100 hour run (40 starts and stops). During a 40 hour contamination test (mesh silica flour) the seal total wear was a maximum of .004 inches. This wear is considered acceptable.

  13. Design guide for helicopter transmission seals

    NASA Technical Reports Server (NTRS)

    Hayden, T. S.; Keller, C. H., Jr.

    1974-01-01

    A detailed approach for the selection and design of seals for helicopter transmissions is presented. There are two major types of seals presently being used and they are lip type seals and mechanical type seals. Lip type seals can be divided in conventional lip seals and hydrodynamic lip seals. Conventional lip seals can be used for slow-speed, low-pressure, low-temperature sealing. Hydrodynamic lip seals although they are as pressure and temperature limited as conventional lip seals, can operate at a higher speed. Mechanical types seals are comprised of face seals and circumferential seals. Face seals are capable of high speed, high pressure, and high temperature. Circumferential seals can be used in high-speed and high-temperature applications, but will leak excessively at moderate pressures. The performance goals of transmission seals are a life that is at least equal to the scheduled overhaul interval of the gearbox component and a leakage rate of near zero.

  14. Helicopter transmission testing at NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Coy, John J.

    1987-01-01

    The helicopter has evolved into a highly valuable air mobile vehicle for both military and civilian needs. The helicopter transmission requires advanced studies to develop a technology base for future rotorcraft advances. A joint helicopter transmission research program between the NASA Lewis Research Center and the U.S. Army Aviation Systems Command has existed since 1970. Program goals are to reduce weight and noise and to increase life and reliability. The current experimental activities at Lewis consist of full-scale helicopter transmission testing, a base effort in gearing technology, and a future effort in noise reduction technology. The experimental facilities at Lewis for helicopter transmission testing are described. A description of each of the rigs is presented along with some significant results and near-term plans.

  15. Thermal and Structural Analysis of Helicopter Transmission Housings Using NASTRAN

    NASA Technical Reports Server (NTRS)

    Howells, R. W.; Sciarra, J. J.; Ng, G. S.

    1976-01-01

    The application of NASTRAN to improve the design of helicopter transmission housings is described. A finite element model of the complete forward rotor transmission housing for the Boeing Vertol CH-47C helicopter was used to study thermal distortion and stress, stress and deflection due to static and dynamic loads, load paths, and design optimization by the control of structural energy distribution. The analytical results are correlated with test data and used to reduce weight and to improve strength, service life, failsafety, and reliability. The techniques presented, although applied herein to helicopter transmissions, are sufficiently general to be applicable to any power transmission system.

  16. Dynamics of a split torque helicopter transmission

    NASA Astrophysics Data System (ADS)

    Rashidi, Majid; Krantz, Timothy

    A high reduction ratio split torque gear train has been proposed as an alternative to a planetary configuration for the final stage of a helicopter transmission. A split torque design allows a high ratio of power-to-weight for the transmission. The design studied in this work includes a pivoting beam that acts to balance thrust loads produced by the helical gear meshes in each of two parallel power paths. When the thrust loads are balanced, the torque is split evenly. A mathematical model was developed to study the dynamics of the system. The effects of time varying gear mesh stiffness, static transmission errors, and flexible bearing supports are included in the model. The model was demonstrated with a test case. Results show that although the gearbox has a symmetric configuration, the simulated dynamic behavior of the first and second compound gears are not the same. Also, results show that shaft location and mesh stiffness tuning are significant design parameters that influence the motions of the system.

  17. Dynamics of a split torque helicopter transmission

    NASA Technical Reports Server (NTRS)

    Rashidi, Majid; Krantz, Timothy

    1992-01-01

    A high reduction ratio split torque gear train has been proposed as an alternative to a planetary configuration for the final stage of a helicopter transmission. A split torque design allows a high ratio of power-to-weight for the transmission. The design studied in this work includes a pivoting beam that acts to balance thrust loads produced by the helical gear meshes in each of two parallel power paths. When the thrust loads are balanced, the torque is split evenly. A mathematical model was developed to study the dynamics of the system. The effects of time varying gear mesh stiffness, static transmission errors, and flexible bearing supports are included in the model. The model was demonstrated with a test case. Results show that although the gearbox has a symmetric configuration, the simulated dynamic behavior of the first and second compound gears are not the same. Also, results show that shaft location and mesh stiffness tuning are significant design parameters that influence the motions of the system.

  18. Bell Helicopter Advanced Rotocraft Transmission (ART) program

    NASA Astrophysics Data System (ADS)

    Henry, Zachary S.

    1995-06-01

    Future rotorcraft transmissions require key emerging material and component technologies using advanced and innovative design practices in order to meet the requirements for a reduced weight to power ratio, a decreased noise level, and a substantially increased reliability. The specific goals for the future rotorcraft transmission when compared with a current state-of-the-art transmission (SOAT) are: (1) a 25 percent weight reduction; (2) a 10 dB reduction in the transmitted noise level; and (3) a system reliability of 5000 hours mean-time-between-removal (MTBR) for the transmission. This report summarizes the work conducted by Bell Helicopter Textron, Inc. to achieve these goals under the Advanced Rotorcraft Transmission (ART) program from 1988 to 1995. The reference aircraft selected by BHTI for the ART program was the Tactical Tiltrotor which is a 17,000 lb gross weight aircraft. A tradeoff study was conducted comparing the ART with a Selected SOAT. The results showed the ART to be 29 percent lighter and up to 13 dB quieter with a calculated MTBR in excess of 5000 hours. The results of the following high risk component and material tests are also presented: (1) sequential meshing high contact ratio planetary with cantilevered support posts; (2) thin dense chrome plated M50 NiL double row spherical roller planetary bearings; (3) reduced kinematic error and increased bending strength spiral bevel gears; (4) high temperature WE43 magnesium housing evaluation and coupon corrosion tests; (5) flexure fatigue tests of precision forged coupons simulating precision forged gear teeth; and (6) flexure fatigue tests of plasma carburized coupons simulating plasma carburized gear teeth.

  19. Bell Helicopter Advanced Rotocraft Transmission (ART) program

    NASA Technical Reports Server (NTRS)

    Henry, Zachary S.

    1995-01-01

    Future rotorcraft transmissions require key emerging material and component technologies using advanced and innovative design practices in order to meet the requirements for a reduced weight to power ratio, a decreased noise level, and a substantially increased reliability. The specific goals for the future rotorcraft transmission when compared with a current state-of-the-art transmission (SOAT) are: (1) a 25 percent weight reduction; (2) a 10 dB reduction in the transmitted noise level; and (3) a system reliability of 5000 hours mean-time-between-removal (MTBR) for the transmission. This report summarizes the work conducted by Bell Helicopter Textron, Inc. to achieve these goals under the Advanced Rotorcraft Transmission (ART) program from 1988 to 1995. The reference aircraft selected by BHTI for the ART program was the Tactical Tiltrotor which is a 17,000 lb gross weight aircraft. A tradeoff study was conducted comparing the ART with a Selected SOAT. The results showed the ART to be 29 percent lighter and up to 13 dB quieter with a calculated MTBR in excess of 5000 hours. The results of the following high risk component and material tests are also presented: (1) sequential meshing high contact ratio planetary with cantilevered support posts; (2) thin dense chrome plated M50 NiL double row spherical roller planetary bearings; (3) reduced kinematic error and increased bending strength spiral bevel gears; (4) high temperature WE43 magnesium housing evaluation and coupon corrosion tests; (5) flexure fatigue tests of precision forged coupons simulating precision forged gear teeth; and (6) flexure fatigue tests of plasma carburized coupons simulating plasma carburized gear teeth.

  20. Signal Detection Theory Applied to Helicopter Transmission Diagnostic Thresholds

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Keller, Jonathan A.; Wade, Daniel R.

    2008-01-01

    Helicopter Health Usage Monitoring Systems (HUMS) have potential for providing data to support increasing the service life of a dynamic mechanical component in the transmission of a helicopter. Data collected can demonstrate the HUMS condition indicator responds to a specific component fault with appropriate alert limits and minimal false alarms. Defining thresholds for specific faults requires a tradeoff between the sensitivity of the condition indicator (CI) limit to indicate damage and the number of false alarms. A method using Receiver Operating Characteristic (ROC) curves to assess CI performance was demonstrated using CI data collected from accelerometers installed on several UH60 Black Hawk and AH64 Apache helicopters and an AH64 helicopter component test stand. Results of the analysis indicate ROC curves can be used to reliably assess the performance of commercial HUMS condition indicators to detect damaged gears and bearings in a helicopter transmission.

  1. Signal Detection Theory Applied to Helicopter Transmission Diagnostic Thresholds

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Keller, Jonathan A.; Wade, Daniel R.

    2009-01-01

    Helicopter Health Usage Monitoring Systems (HUMS) have potential for providing data to support increasing the service life of a dynamic mechanical component in the transmission of a helicopter. Data collected can demonstrate the HUMS condition indicator responds to a specific component fault with appropriate alert limits and minimal false alarms. Defining thresholds for specific faults requires a tradeoff between the sensitivity of the condition indicator (CI) limit to indicate damage and the number of false alarms. A method using Receiver Operating Characteristic (ROC) curves to assess CI performance was demonstrated using CI data collected from accelerometers installed on several UH60 Black Hawk and AH64 Apache helicopters and an AH64 helicopter component test stand. Results of the analysis indicate ROC curves can be used to reliably assess the performance of commercial HUMS condition indicators to detect damaged gears and bearings in a helicopter transmission.

  2. Dynamics of a split torque helicopter transmission

    NASA Astrophysics Data System (ADS)

    Krantz, Timothy L.

    1994-06-01

    Split torque designs, proposed as alternatives to traditional planetary designs for helicopter main rotor transmissions, can save weight and be more reliable than traditional designs. This report presents the results of an analytical study of the system dynamics and performance of a split torque gearbox that uses a balance beam mechanism for load sharing. The Lagrange method was applied to develop a system of equations of motion. The mathematical model includes time-varying gear mesh stiffness, friction, and manufacturing errors. Cornell's method for calculating the stiffness of spur gear teeth was extended and applied to helical gears. The phenomenon of sidebands spaced at shaft frequencies about gear mesh fundamental frequencies was simulated by modeling total composite gear errors as sinusoid functions. Although the gearbox has symmetric geometry, the loads and motions of the two power paths differ. Friction must be considered to properly evaluate the balance beam mechanism. For the design studied, the balance beam is not an effective device for load sharing unless the coefficient of friction is less than 0.003. The complete system stiffness as represented by the stiffness matrix used in this analysis must be considered to precisely determine the optimal tooth indexing position.

  3. Application of face-gear drives in helicopter transmissions

    NASA Astrophysics Data System (ADS)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.

    1992-05-01

    The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.

  4. Application of Face-Gear Drives in Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.

    1992-01-01

    The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.

  5. Efficiency testing of a helicopter transmission planetary reduction stage

    NASA Technical Reports Server (NTRS)

    Handschuh, R. F.; Rohn, D. A.

    1989-01-01

    A parametric study of the efficiency of a 310-kW (420-hp) helicopter transmission planetary test section (four planets) was performed. The purpose was to determine the planetary contribution to the overall transmission power loss. Test parameters varied were oil flow rate, oil inlet temperature, lubricant type, shaft speed, and applied torque. The measured efficiency over all the test variables ranged from 99.44 to 99.75 percent. These experimental results were compared with other experimental and computational results.

  6. Efficiency testing of a helicopter transmission planetary reduction stage

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Rohn, Douglas A.

    1988-01-01

    A parametric study of the efficiency of a 310-kW (420-hp) helicopter transmission planetary test section (four planets) was performed. The purpose was to determine the planetary contribution to the overall transmission power loss. Test parameters varied were oil flow rate, oil inlet temperature, lubricant type, shaft speed, and applied torque. The measured efficiency over all the test variables ranged from 99.44 to 99.75 percent. These experimental results were compared with other experimental and computational results.

  7. Vibration characteristics of OH-58A helicopter main rotor transmission

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Coy, John J.

    1987-01-01

    Experimental vibration tests covering a range of torque and speed conditions were performed on the OH-58A helicopter main rotor transmission at the NASA Lewis Research Center. Signals from accelerometers located on the transmission housing were analyzed by using Fourier spectra, power spectral density functions, and averaging techniques. Most peaks of the Fourier spectra occurred at the spiral bevel and planetary gear mesh harmonics. The highest level of vibration occurred at the spiral bevel meshing frequency. Transmission speed and vibration measurement location had a significant effect on measured vibration; transmission torque and measurement direction had a small effect.

  8. The 3600 hp split-torque helicopter transmission

    NASA Technical Reports Server (NTRS)

    White, G.

    1985-01-01

    Final design details of a helicopter transmission that is powered by GE twin T 700 engines each rated at 1800 hp are presented. It is demonstrated that in comparison with conventional helicopter transmission arrangements the split torque design offers: weight reduction of 15%; reduction in drive train losses of 9%; and improved reliability resulting from redundant drive paths between the two engines and the main shaft. The transmission fits within the NASA LeRC 3000 hp Test Stand and accepts the existing positions for engine inputs, main shaft, connecting drive shafts, and the cradle attachment points. One necessary change to the test stand involved gear trains of different ratio in the tail drive gearbox. Progressive uprating of engine input power from 3600 to 4500 hp twin engine rating is allowed for in the design. In this way the test transmission will provide a base for several years of analytical, research, and component development effort targeted at improving the performance and reliability of helicopter transmission.

  9. System life and reliability modeling for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Savage, M.; Brikmanis, C. K.

    1986-01-01

    A computer program which simulates life and reliability of helicopter transmissions is presented. The helicopter transmissions may be composed of spiral bevel gear units and planetary gear units - alone, in series or in parallel. The spiral bevel gear units may have either single or dual input pinions, which are identical. The planetary gear units may be stepped or unstepped and the number of planet gears carried by the planet arm may be varied. The reliability analysis used in the program is based on the Weibull distribution lives of the transmission components. The computer calculates the system lives and dynamic capacities of the transmission components and the transmission. The system life is defined as the life of the component or transmission at an output torque at which the probability of survival is 90 percent. The dynamic capacity of a component or transmission is defined as the output torque which can be applied for one million output shaft cycles for a probability of survival of 90 percent. A complete summary of the life and dynamic capacity results is produced by the program.

  10. Life and reliability models for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Savage, M.; Knorr, R. J.; Coy, J. J.

    1982-01-01

    Computer models of life and reliability are presented for planetary gear trains with a fixed ring gear, input applied to the sun gear, and output taken from the planet arm. For this transmission the input and output shafts are co-axial and the input and output torques are assumed to be coaxial with these shafts. Thrust and side loading are neglected. The reliability model is based on the Weibull distributions of the individual reliabilities of the in transmission components. The system model is also a Weibull distribution. The load versus life model for the system is a power relationship as the models for the individual components. The load-life exponent and basic dynamic capacity are developed as functions of the components capacities. The models are used to compare three and four planet, 150 kW (200 hp), 5:1 reduction transmissions with 1500 rpm input speed to illustrate their use.

  11. Principal Components Analysis of Triaxial Vibration Data From Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Tumer, Irem Y.; Huff, Edward M.

    2001-01-01

    Research on the nature of the vibration data collected from helicopter transmissions during flight experiments has led to several crucial observations believed to be responsible for the high rates of false alarms and missed detections in aircraft vibration monitoring systems. This work focuses on one such finding, namely, the need to consider additional sources of information about system vibrations. In this light, helicopter transmission vibration data, collected using triaxial accelerometers, were explored in three different directions, analyzed for content, and then combined using Principal Components Analysis (PCA) to analyze changes in directionality. In this paper, the PCA transformation is applied to 176 test conditions/data sets collected from an OH58C helicopter to derive the overall experiment-wide covariance matrix and its principal eigenvectors. The experiment-wide eigenvectors. are then projected onto the individual test conditions to evaluate changes and similarities in their directionality based on the various experimental factors. The paper will present the foundations of the proposed approach, addressing the question of whether experiment-wide eigenvectors accurately model the vibration modes in individual test conditions. The results will further determine the value of using directionality and triaxial accelerometers for vibration monitoring and anomaly detection.

  12. OH-58 helicopter transmission failure analysis

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Coy, J. J.; Hatvani, B. R.

    1976-01-01

    The OH-58 main transmission gearbox was run at varying output torques, speeds, and oil cooling rates. The gearbox was subsequently run to destruction by draining the oil from the gearbox while operating at a speed of 6200 revs per minute and 36,000 inch-pounds output torque. Primary cause of gearbox failure was overheating and melting of the planet bearing aluminum cages. Complete failure of the gearbox occurred in 28 1/2 minutes after the oil pressure dropped to zero. The alternating and maximum stresses in the gearbox top case were approximately 10 percent of the endurance limit for the material. Deflection of the bevel gear at 67000 inch-pounds output torque indicate a marginal stiffness for the bevel gear supporting system.

  13. NASA transmission research and its probable effects on helicopter transmission design

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    Transmissions studied for application to helicopters in addition to the more conventional geared transmissions include hybrid (traction/gear), bearingless planetary, and split torque transmissions. Research is being performed to establish the validity of analysis and computer codes developed to predict the performance, efficiency, life, and reliability of these transmissions. Results of this research should provide the transmission designer with analytical tools to design for minimum weight and noise with maximum life and efficiency. In addition, the advantages and limitations of drive systems as well as the more conventional systems will be defined.

  14. Dynamic analysis of multimesh-gear helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Choy, Fred K.; Townsend, Dennis P.; Oswald, Fred B.

    1988-01-01

    A dynamic analysis of multimesh-gear helicopter transmission systems was performed by correlating analytical simulations with experimental investigations. The two computer programs used in this study, GRDYNMLT and PGT, were developed under NASA/Army sponsorship. Parametric studies of the numerical model with variations on mesh damping ratios, operating speeds, tip-relief tooth modifications, and tooth-spacing errors were performed to investigate the accuracy, application, and limitations of the two computer programs. Although similar levels of dynamic loading were predicted by both programs, the computer code GRDYNMLT was found to be superior and broader in scope. Results from analytical work were also compared with experimental data obtained from the U.S. Army's UH-60A Black Hawk 2240-kW (3000-hp) class, twin-engine helicopter transmission tested at the NASA Lewis Research Center. Good correlation in gear stresses was obtained between the analytical model simulated by GRDYNMLT and the experimental measurements. More realistic mesh damping can be predicted through experimental data correlation.

  15. Helicopter transmission arrangements with split-torque gear trains

    NASA Technical Reports Server (NTRS)

    White, G.

    1983-01-01

    As an alternative to component development, the case for improved drive-train configuration is argued. In particular, the use of torque-splitting gear trains is proposed as a practicable means of improving the effectiveness of helicopter main gearboxes.

  16. Code to Optimize Load Sharing of Split-Torque Transmissions Applied to the Comanche Helicopter

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Most helicopters now in service have a transmission with a planetary design. Studies have shown that some helicopters would be lighter and more reliable if they had a transmission with a split-torque design instead. However, a split-torque design has never been used by a U.S. helicopter manufacturer because there has been no proven method to ensure equal sharing of the load among the multiple load paths. The Sikorsky/Boeing team has chosen to use a split-torque transmission for the U.S. Army's Comanche helicopter, and Sikorsky Aircraft is designing and manufacturing the transmission. To help reduce the technical risk of fielding this helicopter, NASA and the Army have done the research jointly in cooperation with Sikorsky Aircraft. A theory was developed that equal load sharing could be achieved by proper configuration of the geartrain, and a computer code was completed in-house at the NASA Lewis Research Center to calculate this optimal configuration.

  17. Finite element analysis using NASTRAN applied to helicopter transmission vibration/noise reduction

    NASA Technical Reports Server (NTRS)

    Howells, R. W.; Sciarra, J. J.

    1975-01-01

    A finite element NASTRAN model of the complete forward rotor transmission housing for the Boeing Vertol CH-47 helicopter was developed and applied to reduce transmission vibration/noise at its source. In addition to a description of the model, a technique for vibration/noise prediction and reduction is outlined. Also included are the dynamic response as predicted by NASTRAN, test data, the use of strain energy methods to optimize the housing for minimum vibration/noise, and determination of design modifications which will be manufactured and tested. The techniques presented are not restricted to helicopters but are applicable to any power transmission system. The transmission housing model developed can be used further to evaluate static and dynamic stresses, thermal distortions, deflections and load paths, fail-safety/vulnerability, and composite materials.

  18. Research requirements for development of advanced-technology helicopter transmissions. [reduction of maintenance costs

    NASA Technical Reports Server (NTRS)

    Lemanski, A. J.

    1976-01-01

    Helicopter drive-system technology which would result in the largest benefit in direct maintenance cost when applied to civil helicopters in the 1980 timeframe was developed. A prototype baseline drive system based on 1975 technology provided the basis for comparison against the proposed advanced technology in order to determine the potential for each area recommended for improvement. A specific design example of an advanced-technology main transmission is presented to define improvements for maintainability, weight, producibility, reliability, noise, vibration, and diagnostics. Projections of the technology achievable in the 1980 timeframe are presented. Based on this data, the technologies with the highest payoff (lowest direct maintenance cost) for civil-helicopter drive systems are identified.

  19. Advanced Rotorcraft Transmission (ART) program-Boeing helicopters status report

    NASA Technical Reports Server (NTRS)

    Lenski, Joseph W., Jr.; Valco, Mark J.

    1991-01-01

    The Advanced Rotorcraft Transmission (ART) program is structured to incorporate key emerging material and component technologies into an advanced rotorcraft transmission with the intention of making significant improvements in the state of the art (SOA). Specific objectives of ART are: (1) Reduce transmission weight by 25 pct.; (2) Reduce transmission noise by 10 dB; and (3) Improve transmission life and reliability, while extending Mean Time Between Removal to 5000 hr. Boeing selected a transmission sized for the Tactical Tilt Rotor (TTR) aircraft which meets the Future Air Attack Vehicle (FAVV) requirements. Component development testing will be conducted to evaluate the high risk concepts prior to finalizing the advanced transmission configuration. The results of tradeoff studies and development test which were completed are summarized.

  20. Development of circumferential seal for helicopter transmissions: Results of bench and flight tests

    NASA Technical Reports Server (NTRS)

    Strom, T. N.; Ludwig, L. P.

    1975-01-01

    A modified circumferential segmented ring seal was designed for direct replacement of a helicopter transmission elastomeric lip seal operating on a shaft diameter of 13.91 centimeters (5.481 in.) at sliding velocities to 52.48 m/sec (10 330 ft/min). The modifications involved the garter spring tension, shaft roundness, seal housing flatness, and pumping grooves to inhibit leakage. Operation of the seals in bench tests under simulated helicopter transmission conditions revealed that the seal leakage rate was within acceptable limits and that the wear rate was negligible. The low leakage and wear rates were confirmed in flight tests of 600 and 175 hours (sliding speed, 48.11 m/sec (9470 ft/min)). An additional 200 hours of air worthiness qualification testing (aircraft tie down) demonstrated that the seal can operate at the advanced sliding conditions of 52.48 m/sec (10 330 ft/min).

  1. Experimental testing of prototype face gears for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Handschuh, R.; Lewicki, D.; Bossler, R.

    1992-01-01

    An experimental program to test the feasibility of using face gears in a high-speed and high-power environment was conducted. Four face gear sets were tested, two sets at a time, in a closed-loop test stand at pinion rotational speeds to 19,100 rpm and to 271 kW. The test gear sets were one-half scale of the helicopter design gear set. Testing the gears at one-eighth power, the test gear set had slightly increased bending and compressive stresses when compared to the full scale design. The tests were performed in the LeRC spiral bevel gear test facility. All four sets of gears successfully ran at 100 percent of design torque and speed for 30 million pinion cycles, and two sets successfully ran at 200 percent of torque for an additional 30 million pinion cycles. The results, although limited, demonstrated the feasibility of using face gears for high-speed, high-load applications.

  2. Feasibility study of negative lift circumferential type seal for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Goldring, E. N.

    1977-01-01

    A new seal concept, the negative lift circumferential type seal, was evaluated under simulated helicopter transmission conditions. The bore of the circumferential seal contains step type geometry which produces a negative lift that urges the sealing segments towards the shaft surface. The seal size was a 2.5 inch bore and the test speeds were 7000 and 14,250 rpm. During the 300 hour test at typical transmission seal pressure (to 2 psig) the leakage was within acceptable limits and generally less than 0.1 cc/hour during the last 150 hours of testing. The wear to the carbon segments during the 300 hours was negligible.

  3. Study of the kinematic and dynamic characteristics of a wormgear transmission for helicopter applications

    NASA Technical Reports Server (NTRS)

    Sun, D. C.; Yuan, Qin

    1994-01-01

    The first phase of the study of the performance of a wormgear transmission is reported. In this phase the work included the selection of a double-enveloping wormgear type, and its dimensions, suitable for use in helicopter transmissions; the 3-D graphics representation of the selected wormgear using the I-DEAS software; the analysis of the kinematics of meshing; the analysis of load sharing among the meshing teeth; and the implementation of the analyses in a computer program. The report describes the analyses, their results, and the use of the computer programs.

  4. Identification and proposed control of helicopter transmission noise at the source

    NASA Technical Reports Server (NTRS)

    Coy, John J.; Handschuh, Robert F.; Lewicki, David G.; Huff, Ronald G.; Krejsa, Eugene A.; Karchmer, Allan M.

    1987-01-01

    Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. Work conducted by the NASA Lewis Research Center in measuring cabin interior noise and in relating the noise spectrum to the gear vibration of the Army OH-58 helicopter is described. Flight test data indicate that the planetary gear train is a major source of cabin noise and that other low frequency sources are present that could dominate the cabin noise. Companion vibration measurements were made in a transmission test stand, revealing that the single largest contributor to the transmission vibration was the spiral bevel gear mesh. The current understanding of the nature and causes of gear and transmission noise is discussed. It is believed that the kinematical errors of the gear mesh have a strong influence on that noise. The completed NASA/Army sponsored research that applies to transmission noise reduction is summarized. The continuing research program is also reviewed.

  5. Identification and proposed control of helicopter transmission noise at the source

    NASA Technical Reports Server (NTRS)

    Coy, John J.; Handschuh, Robert F.; Lewicki, David G.; Huff, Ronald G.; Krejsa, Eugene A.; Karchmer, Allan M.; Coy, John J.

    1988-01-01

    Helicopter cabin interiors require noise treatment which is expensive and adds weight. The gears inside the main power transmission are major sources of cabin noise. Work conducted by the NASA Lewis Research Center in measuring cabin interior noise and in relating the noise spectrum to the gear vibration of the Army OH-58 helicopter is described. Flight test data indicate that the planetary gear train is a major source of cabin noise and that other low frequency sources are present that could dominate the cabin noise. Companion vibration measurements were made in a transmission test stand, revealing that the single largest contributor to the transmission vibration was the spiral bevel gear mesh. The current understanding of the nature and causes of gear and transmission noise is discussed. It is believed that the kinematical errors of the gear mesh have a strong influence on that noise. The completed NASA/Army sponsored research that applies to transmission noise reduction is summarized. The continuing research program is also reviewed.

  6. Face-gear drives: Design, analysis, and testing for helicopter transmission applications

    NASA Astrophysics Data System (ADS)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.

    1992-10-01

    The use of face-gears in helicopter transmissions was explored. A light-weight, split-torque transmission design utilizing face-gears is described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, grinding, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. An analytical study showed that the face-gear drive is relatively insensitive to gear misalignment with respect to transmission errors, but the tooth contact is affected by misalignment. A method of localizing the bearing contact to permit operation with misalignment was explored. Two new methods for grinding of the face-gear tooth surfaces were also investigated. The proper choice of shaft stiffness enabled good load sharing in the split-torque transmission design. Face-gear experimental studies were also conducted. These tests demonstrated the feasibility of face-gears in high-speed, high-load applications such as helicopter transmissions.

  7. Face-gear drives: Design, analysis, and testing for helicopter transmission applications

    NASA Technical Reports Server (NTRS)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.

    1992-01-01

    The use of face-gears in helicopter transmissions was explored. A light-weight, split-torque transmission design utilizing face-gears is described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, grinding, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. An analytical study showed that the face-gear drive is relatively insensitive to gear misalignment with respect to transmission errors, but the tooth contact is affected by misalignment. A method of localizing the bearing contact to permit operation with misalignment was explored. Two new methods for grinding of the face-gear tooth surfaces were also investigated. The proper choice of shaft stiffness enabled good load sharing in the split-torque transmission design. Face-gear experimental studies were also conducted. These tests demonstrated the feasibility of face-gears in high-speed, high-load applications such as helicopter transmissions.

  8. Development of Novel Methods for the Reduction of Noise and Weight in Helicopter Transmissions

    NASA Astrophysics Data System (ADS)

    Dimofte, Florin; Keith, Theo G., Jr.

    2003-01-01

    Over the 70-year evolution of the helicopter, man's understanding of vibration control has greatly increased. However, in spite of the increased performance, the extent of helicopter vibration problems has not significantly diminished. Crew vibration and noise remains important factors in the design of all current helicopters. With more complex and critical demands being placed on aircrews, it is essential that vibration and noise not impair their performance. A major source of helicopter cabin noise (which has been measured at a sound pressure level of over 100 dB) is the gearbox. Reduction of this noise has been a goal of NASA and the U.S. Army. Gear mesh noise is typically in the frequency range of 1000 to 3000 Hz, a range important for speech. A requirement for U.S. Army/NASA Advanced Rotorcraft Transmission project has been a 10-dB reduction compared to current designs. A combined analytical/experimental effort has been underway, since the end of the 80's, to study effects of design parameters on noise production. The noise generated by the gear mesh can be transmitted to the surrounding media through the bearings that support the gear shaft. Therefore, the use of fluid film bearings instead of rolling element bearings could reduce the transmission noise by 10 dB. In addition, the fluid film bearings that support the gear shaft can change the dynamics of the gear assembly by providing damping to the system and by being softer than rolling element bearings. Wave bearings can attenuate, and filter, the noise generated by a machine component due to the dynamic stiffness and damping coefficients. The attenuation ratio could be as large as 35-40 dB. The noise components at higher frequencies than a synchronous frequency can be almost eliminated.

  9. Helicopter Transmission Research at NASA Lewis Research Center

    DTIC Science & Technology

    1988-11-10

    surface fatigue life and power-to-weight ratio of transmissions. High-contact-ratio (HCR) gears have at least two pairs of teeth in contact at all times...pairs of teeth , the individual tooth loading is less for HCR than for LCR designs, 3 thereby enabling a higher power-to-weight ratio. HCR gears...stresses, and surface damage factors. The program can analyze a variety of both epicyclic and single mesh systems with spur and helical gear teeth

  10. Effect of Advanced Component Technology on Helicopter Transmissions

    DTIC Science & Technology

    1989-01-01

    same basic configuration, by a flight hardware air-oil cooler mounted on the the same number of teeth on the gears, and the same transmission (with... torque were then adjusted 3 (40 ’>C nearly all the accelerometers (Fig. 8(a)). Thus, the ATT peak stresses were about three times higher than number of...ratio planetary gears. torque and speed conditions. Vibration and efficiency experiments were performed on the ATT and compared to INTRODUCTION the OH

  11. Transmission Bearing Damage Detection Using Decision Fusion Analysis

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Lewicki, David G.; Decker, Harry J.

    2004-01-01

    A diagnostic tool was developed for detecting fatigue damage to rolling element bearings in an OH-58 main rotor transmission. Two different monitoring technologies, oil debris analysis and vibration, were integrated using data fusion into a health monitoring system for detecting bearing surface fatigue pitting damage. This integrated system showed improved detection and decision-making capabilities as compared to using individual monitoring technologies. This diagnostic tool was evaluated by collecting vibration and oil debris data from tests performed in the NASA Glenn 500 hp Helicopter Transmission Test Stand. Data was collected during experiments performed in this test rig when two unanticipated bearing failures occurred. Results show that combining the vibration and oil debris measurement technologies improves the detection of pitting damage on spiral bevel gears duplex ball bearings and spiral bevel pinion triplex ball bearings in a main rotor transmission.

  12. Analysis of In-Flight Vibration Measurements from Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Mosher, Marianne; Huff, Ed; Barszcz

    2004-01-01

    In-flight vibration measurements from the transmission of an OH-58C KIOWA are analyzed. In order to understand the effect of normal flight variation on signal shape, the first gear mesh components of the planetary gear system and bevel gear are studied in detail. Systematic patterns occur in the amplitude and phase of these signal components with implications for making time synchronous averages and interpreting gear metrics in flight. The phase of the signal component increases as the torque increases; limits on the torque range included in a time synchronous average may now be selected to correspond to phase change limits on the underlying signal. For some sensors and components, an increase in phase variation and/or abrupt change in the slope of the phase dependence on torque are observed in regions of very low amplitude of the signal component. A physical mechanism for this deviation is postulated. Time synchronous averages should not be constructed in torque regions with wide phase variation.

  13. Design, manufacture and spin test of high contact ratio helicopter transmission utilizing Self-Aligning Bearingless Planetary (SABP)

    NASA Technical Reports Server (NTRS)

    Folenta, Dezi; Lebo, William

    1988-01-01

    A 450 hp high ratio Self-Aligning Bearingless Planetary (SABP) for a helicopter application was designed, manufactured, and spin tested under NASA contract NAS3-24539. The objective of the program was to conduct research and development work on a high contact ratio helical gear SABP to reduce weight and noise and to improve efficiency. The results accomplished include the design, manufacturing, and no-load spin testing of two prototype helicopter transmissions, rated at 450 hp with an input speed of 35,000 rpm and an output speed of 350 rpm. The weight power density ratio of these gear units is 0.33 lb hp. The measured airborne noise at 35,000 rpm input speed and light load is 94 dB at 5 ft. The high speed, high contact ratio SABP transmission appears to be significantly lighter and quieter than comtemporary helicopter transmissions. The concept of the SABP is applicable not only to high ratio helicopter type transmissions but also to other rotorcraft and aircraft propulsion systems.

  14. Identification and Proposed Control of Helicopter Transmission Noise at the Source

    DTIC Science & Technology

    1987-03-19

    future work on helicopter noise are presented. OH-SB HELICOPTER & TRANSMISION The OH-58C Helicopter is the Army’s Light Scout/Attack helicopter...grinding machine . As currently manufactured, spiral bevel gears do not have conjugate action. Spiral bevel gears with conjugate action were examined...was lost. The process of grinding teeth on a spiral bevel gear is a function of many different settings on the gear grinding machine . Nominally similar

  15. Gear tooth stress measurements on the UH-60A helicopter transmission

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.

    1987-01-01

    The U.S. Army UH-60A (Black Hawk) 2200-kW (3000-hp) class twin-engine helicopter transmission was tested at the NASA Lewis Research Center. Results from these experimental (strain-gage) stress tests will enhance the data base for gear stress levels in transmissions of a similar power level. Strain-gage measurements were performed on the transmission's spiral-bevel combining pinions, the planetary Sun gear, and ring gear. Tests were performed at rated speed and at torque levels 25 to 100 percent that of rated. One measurement series was also taken at a 90 percent speed level. The largest stress found was 760 MPa (110 ksi) on the combining pinion fillet. This is 230 percent greater than the AGMA index stress. Corresponding mean and alternating stresses were 300 and 430 MPa (48 and 62 ksi). These values are within the range of successful test experience reported for other transmissions. On the fillet of the ring gear, the largest stress found was 410 MPa (59 ksi). The ring-gear peak stress was found to be 11 percent less than an analytical (computer simulation) value and it is 24 percent greater than the AGMA index stress. A peak compressive stress of 650 MPa (94 ksi) was found at the center of the Sun gear tooth root.

  16. Elliptic Grid Generation of Spiral-Bevel Pinion Gear Typical of OH-58 Helicopter Transmission

    NASA Technical Reports Server (NTRS)

    Kaul, Upender K.; Huff, Edward M.

    2002-01-01

    This paper discusses the source term treatment in the numerical solution of elliptic partial differential equations for an interior grid generation problem in generalized curvilinear coordinates. The geometry considered is that of a planar cross-section of a generic spiral-bevel gear tooth typical of a pinion in the OH-58 helicopter transmission. The source terms used are appropriate for an interior grid domain where all the boundaries are prescribed via a combination of Dirichlet and Neumann boundary conditions. New constraints based on the Green's Theorem are derived which uniquely determine the coefficients in the source terms. These constraints are designed for boundary clustered grids where gradients in physical quantities need to be resolved adequately. However, it is seen that the present formulation works satisfactorily for mild clustering also. Thus, a fully automated elliptic grid generation technique is made possible where there is no need for a parametric study of these parameters since the new relations fix these free parameters uniquely.

  17. Analytical investigation of the pericyclic variable-speed transmission system for helicopter main-gearbox

    NASA Astrophysics Data System (ADS)

    Saribay, Zihni Burcay

    and load carrying capacity of the PVT face-gears are analyzed at the helicopter torque levels. The dynamic motion of the nutating gear mechanisms is studied to capture the load carrying capacity of the PVT support bearings. A design analysis of the PVT system with 24:1 reduction ratio at 764HP power level is conducted to replace 3 reduction stages of the existing K-MAX intermeshing rotor transmission system. The design and analysis tools established in this research are applied in the design study. The achieved design is compared to the existing K-MAX transmission. Approximately 50% weight reduction and 70% volume reduction are accomplished with the PVT system with less than 1% lower efficiency than existing K-MAX drive train gears.

  18. Evaluation of MEMS-Based Wireless Accelerometer Sensors in Detecting Gear Tooth Faults in Helicopter Transmissions

    NASA Technical Reports Server (NTRS)

    Lewicki, David George; Lambert, Nicholas A.; Wagoner, Robert S.

    2015-01-01

    The diagnostics capability of micro-electro-mechanical systems (MEMS) based rotating accelerometer sensors in detecting gear tooth crack failures in helicopter main-rotor transmissions was evaluated. MEMS sensors were installed on a pre-notched OH-58C spiral-bevel pinion gear. Endurance tests were performed and the gear was run to tooth fracture failure. Results from the MEMS sensor were compared to conventional accelerometers mounted on the transmission housing. Most of the four stationary accelerometers mounted on the gear box housing and most of the CI's used gave indications of failure at the end of the test. The MEMS system performed well and lasted the entire test. All MEMS accelerometers gave an indication of failure at the end of the test. The MEMS systems performed as well, if not better, than the stationary accelerometers mounted on the gear box housing with regards to gear tooth fault detection. For both the MEMS sensors and stationary sensors, the fault detection time was not much sooner than the actual tooth fracture time. The MEMS sensor spectrum data showed large first order shaft frequency sidebands due to the measurement rotating frame of reference. The method of constructing a pseudo tach signal from periodic characteristics of the vibration data was successful in deriving a TSA signal without an actual tach and proved as an effective way to improve fault detection for the MEMS.

  19. Testing of UH-60A helicopter transmission in NASA Lewis 2240-kW (3000-hp) facility

    NASA Technical Reports Server (NTRS)

    Mitchell, A. M.; Oswald, F. B.; Coe, H. H.

    1986-01-01

    The U.S. Army's UH-60A Black Hawk 2240-kW (3000-hp) class, twin-engine helicopter transmission was tested at the NASA Lewis Research Center. The vibration and efficiency test results will be used to enhance the data base for similar-class helicopters. Most of the data were obtained for a matrix of test conditions of 50 to 100 percent of rated rotor speed and 20 to 100 percent of rated input power. The transmission's mechanical efficiency at 100 percent of rated power was 97.3 and 97.5 percent with its inlet oil maintained at 355 and 372 K (180 and 210 F), respectively. The highest vibration reading was 72 g's rms at the upper housing side wall. Other vibration levels measured near the gear meshes are reported.

  20. Dynamics of a split torque helicopter transmission. M.S. Thesis - Cleveland State Univ.

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    1994-01-01

    Split torque designs, proposed as alternatives to traditional planetary designs for helicopter main rotor transmissions, can save weight and be more reliable than traditional designs. This report presents the results of an analytical study of the system dynamics and performance of a split torque gearbox that uses a balance beam mechanism for load sharing. The Lagrange method was applied to develop a system of equations of motion. The mathematical model includes time-varying gear mesh stiffness, friction, and manufacturing errors. Cornell's method for calculating the stiffness of spur gear teeth was extended and applied to helical gears. The phenomenon of sidebands spaced at shaft frequencies about gear mesh fundamental frequencies was simulated by modeling total composite gear errors as sinusoid functions. Although the gearbox has symmetric geometry, the loads and motions of the two power paths differ. Friction must be considered to properly evaluate the balance beam mechanism. For the design studied, the balance beam is not an effective device for load sharing unless the coefficient of friction is less than 0.003. The complete system stiffness as represented by the stiffness matrix used in this analysis must be considered to precisely determine the optimal tooth indexing position.

  1. Investigation on experimental techniques to detect, locate and quantify gear noise in helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Flanagan, P. M.; Atherton, W. J.

    1985-01-01

    A robotic system to automate the detection, location, and quantification of gear noise using acoustic intensity measurement techniques has been successfully developed. Major system components fabricated under this grant include an instrumentation robot arm, a robot digital control unit and system software. A commercial, desktop computer, spectrum analyzer and two microphone probe complete the equipment required for the Robotic Acoustic Intensity Measurement System (RAIMS). Large-scale acoustic studies of gear noise in helicopter transmissions cannot be performed accurately and reliably using presently available instrumentation and techniques. Operator safety is a major concern in certain gear noise studies due to the operating environment. The man-hours needed to document a noise field in situ is another shortcoming of present techniques. RAIMS was designed to reduce the labor and hazard in collecting data and to improve the accuracy and repeatability of characterizing the acoustic field by automating the measurement process. Using RAIMS a system operator can remotely control the instrumentation robot to scan surface areas and volumes generating acoustic intensity information using the two microphone technique. Acoustic intensity studies requiring hours of scan time can be performed automatically without operator assistance. During a scan sequence, the acoustic intensity probe is positioned by the robot and acoustic intensity data is collected, processed, and stored.

  2. Testing of YUH-61A helicopter transmission in NASA Lewis 2240-kW (3000-hp facility

    NASA Technical Reports Server (NTRS)

    Mitchell, A. M.; Oswald, F. B.; Schuller, F. T.

    1986-01-01

    A helicopter transmission that was being considered for the Army's Utility Tactical Transport Attack System (UTTAS) was tested in the NASA Lewis 2240-kW (3000-hp) test facility to obtain the transmission's operational data. The results will form a vibration and efficiency data base for evaluation similar-class helicopter transmissions. The transmission's mechanical efficiency was determined to be 98.7 percent at its rated power level of 2080 kW (2792 hp). At power levels up to 113 percent of rated the transmission displayed 56 percent higher vibration acceleration levels on the right input than on the left input. Both vibration signature analysis and final visual inspection indicated that the right input spiral-bevel gear had poor contact patterns. The highest vibration meter level was 52 g's rms at the accessory gear, which had free-wheeling gearsets. At 113 percent power and 100 percent rated speed the vibration meter levels generally ranged from 3 to 25 g's rms.

  3. Transmission error and load distribution analysis of spur and double helical gear pairs used in a split path helicopter transmission design

    NASA Astrophysics Data System (ADS)

    Hochmann, David; Houser, Donald R.; Thomas, Jacob

    1991-05-01

    Because the reduction of gear noise in next-generation rotorcraft depends on the reduction of transmission errors, attention is presently given to the prediction of such errors and the load distributions of both a spur-gear pair and a double helical gear train used in a split-path helicopter transmission. Two cases are examined: (1) the spur gear mesh between the spur shaft and the lower spur/helical shaft, and (2) the double helical gear mesh between the lower spur/helical shaft and the output bull bear shaft.

  4. A New Helicopter Transmission Model for Condition-Based Maintenance Technologies Using First Principles

    DTIC Science & Technology

    2009-09-01

    Frequency Analysis of Helicopter Gearbox Faults . Mechanical Systems and Signals Processing 2000, 14 (4), 579–595. 14. Dempsey, P.; Keller, J.; Wade...35. Wu, B.; Saxena, A.; Patrick, R.; Vachtsevanos, G. Vibration Monitoring for Fault Diagnosis of Helicopter Planetary Gears. Proceedings of the...operating conditions to include faults . One such fault condition simulates the wear of gear tooth contact surfaces. The nature of the fault and its

  5. Full-scale transmission testing to evaluate advanced lubricants

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Decker, Harry J.; Shimski, John T.

    1992-01-01

    Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500 hp helicopter transmission test stand. The testing was part of a lubrication program. The objectives are to develop and show a separate lubricant for gearboxes with improved performance in life and load carrying capacity. The goal was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 based reference oil and then to run identical tests with improved lubricants and show improved performance. The tests were directed at parts that failed due to marginal lubrication from Navy field experience. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hrs of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring.

  6. A comparative study and application of continuously variable transmission to a single main rotor heavy lift helicopter

    NASA Astrophysics Data System (ADS)

    Hameer, Sameer

    Rotorcraft transmission design is limited by empirical weight trends that are proportional to the power/torque raised to the two-thirds coupled with the relative inexperience industry has with the employment of variable speed transmission to heavy lift helicopters of the order of 100,000 lbs gross weight and 30,000 installed horsepower. The advanced rotorcraft transmission program objectives are to reduce transmission weight by at least 25%, reduce sound pressure levels by at least 10 dB, have a 5000 hr mean time between removal, and also incorporate the use of split torque technology in rotorcraft drivetrains of the future. The major obstacle that challenges rotorcraft drivetrain design is the selection, design, and optimization of a variable speed transmission in the goal of achieving a 50% reduction in rotor speed and its ability to handle high torque with light weight gears, as opposed to using a two-speed transmission which has inherent structural problems and is highly unreliable due to the embodiment of the traction type transmission, complex clutch and brake system. This thesis selects a nontraction pericyclic continuously variable transmission (P-CVT) as the best approach for a single main rotor heavy lift helicopter. The objective is to target and overcome the above mentioned obstacle for drivetrain design. Overcoming this obstacle provides advancement in the state of the art of drivetrain design over existing planetary and split torque transmissions currently used in helicopters. The goal of the optimization process was to decrease weight, decrease noise, increase efficiency, and increase safety and reliability. The objective function utilized the minimization of the weight and the major constraint is the tooth bending stress of the facegears. The most important parameters of the optimization process are weight, maintainability, and reliability which are cross-functionally related to each other, and these parameters are related to the torques and

  7. Development of a full-scale transmission testing procedure to evaluate advanced lubricants

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Decker, Harry J.; Shimski, John T.

    1992-01-01

    Experimental tests were performed on the OH-58A helicopter main rotor transmission in the NASA Lewis 500-hp Helicopter Transmission Test Stand. The testing was part of a joint Navy/NASA/Army lubrication program. The objective of the program was to develop a separate lubricant for gearboxes and demonstrate an improved performance in life and load-carrying capacity. The goal of the experiments was to develop a testing procedure to fail certain transmission components using a MIL-L-23699 base reference oil, then run identical tests with improved lubricants and demonstrate performance. The tests were directed at failing components that the Navy has had problems with due to marginal lubrication. These failures included mast shaft bearing micropitting, sun gear and planet bearing fatigue, and spiral bevel gear scoring. A variety of tests were performed and over 900 hours of total run time accumulated for these tests. Some success was achieved in developing a testing procedure to produce sun gear and planet bearing fatigue failures. Only marginal success was achieved in producing mast shaft bearing micropitting and spiral bevel gear scoring.

  8. Experimental Analysis of Mast Lifting and Bending Forces on Vibration Patterns Before and After Pinion Reinstallation in an OH-58 Transmission Test Rig

    NASA Technical Reports Server (NTRS)

    Huff, Edward M.; Lewicki, David G.; Tumer, Irem Y.; Decker, Harry; Barszez, Eric; Zakrajsek, James J.; Norvig, Peter (Technical Monitor)

    2000-01-01

    As part of a collaborative research program between NASA Ames Research Center (ARC), NASA Glenn Research Center (GRC), and the US Army Laboratory, a series of experiments is being performed in GRC's 500 HP OH-58 Transmission Test Rig facility and ARC's AH-I Cobra and OH-58c helicopters. The findings reported in this paper were drawn from Phase-I of a two-phase test-rig experiment, and are focused on the vibration response of an undamaged pinion gear operating in the transmission test rig. To simulate actual flight conditions, the transmission system was run at three torque levels, as well as two mast lifting and two mast bending levels. The test rig was also subjected to disassembly and reassembly of the main pinion housing to simulate the effect of maintenance operations. An analysis of variance based on the total power of the spectral distribution indicates the relative effect of each experimental factor, including Wong interactions with torque. Reinstallation of the main pinion assembly is shown to introduce changes in the vibration signature, suggesting the possibility of a strong effect of maintenance on HUMS design and use. Based on these results, further research will be conducted to compare these vibration responses with actual OH58c helicopter transmission vibration patterns.

  9. Investigation of Advanced Helicopter Structural Designs. Volume 2. Free Planetary Transmission Drive

    DTIC Science & Technology

    1976-05-01

    f led £ft<"-S<P𔄁Zä \\ iECuBITy CLASSIFICATION OF TMIS P»OI! flWun Dal« Enfrmd) CUMENTATION PAGE 2 OOVT ACCESSION NO 4 TITLE ’«nrf...and Gear Stresses 60 y Weight Comparison of Free ^ lanet with Conventional Two-Stage 6l Planetary Transmission 10 Cost Comparison of Free...PLANE L_L_ *T +- 4 «-S TRANSVERSE PLANE Figure 9. Free Planet Schematics - Four Load 23 GUd. —L~zi C TMGENTIAL FORCE PLANE OPPOSITE ROTATION

  10. Boeing Helicopters Advanced Rotorcraft Transmission (ART) Program summary of component tests

    NASA Technical Reports Server (NTRS)

    Lenski, Joseph W., Jr.; Valco, Mark J.

    1992-01-01

    The principal objectives of the ART program are briefly reviewed, and the results of advanced technology component tests are summarized. The tests discussed include noise reduction by active cancellation, hybrid bidirectional tapered roller bearings, improved bearing life theory and friction tests, transmission lube study with hybrid bearings, and precision near-net-shape forged spur gears. Attention is also given to the study of high profile contact ratio noninvolute tooth form spur gears, parallel axis gear noise study, and surface modified titanium accessory spur gears.

  11. Boeing Helicopters Advanced Rotorcraft Transmission (ART) Program summary of component tests

    NASA Astrophysics Data System (ADS)

    Lenski, Joseph W., Jr.; Valco, Mark J.

    1992-07-01

    The principal objectives of the ART program are briefly reviewed, and the results of advanced technology component tests are summarized. The tests discussed include noise reduction by active cancellation, hybrid bidirectional tapered roller bearings, improved bearing life theory and friction tests, transmission lube study with hybrid bearings, and precision near-net-shape forged spur gears. Attention is also given to the study of high profile contact ratio noninvolute tooth form spur gears, parallel axis gear noise study, and surface modified titanium accessory spur gears.

  12. Helicopter Transmission Oil Discolouration

    DTIC Science & Technology

    2012-02-01

    z Mass to charge ratio NaOH Sodium Hydroxide SEM-EDS Scanning Electron Microscopy - Energy Dispersive Spectroscopy TRGB Tail Rotor Gear Box...515 or H-537 specification. A previous investigation into these field incidents identified one of the oil additives as potentially being the cause of...chelate, thus removing the catalytic potential of the metal ions. One disadvantage of chelating additives is they may accelerate the transfer of

  13. Helicopter Strakes

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Langley Research Center has done extensive research into the effectiveness of tail boom strakes on conventional tail rotor helicopters. (A strake is a "spoiler" whose purpose is to alter the airflow around an aerodynamic body.) By placing strakes on a tail boom, the air loading can be changed, thrust and power requirements of the tail rotor can be reduced, and helicopter low speed flight handling qualities are improved. This research led to the incorporation of tail boom strakes on three production-type commercial helicopters manufactured by McDonnell Douglas Helicopter Company.

  14. Helicopter problems

    NASA Technical Reports Server (NTRS)

    Kussner, H G

    1937-01-01

    The present report deals with a number of the main problems requiring solution in the development of helicopters and concerning the lift, flying performance, stability, and drive. A complete solution is given for the stability of the helicopter with rigid blades and control surfaces. With a view to making a direct-lift propeller sufficient without the addition of auxiliary propellers, the "flapping drive" is assessed and its efficiency calculated.

  15. The helicopter - some ergonomic factors.

    PubMed

    Lovesey, E J

    1975-09-01

    Helicopter pilots are some of the hardest working human operators, because of the machine's inherant instability and control problems. This article covers some aspects where ergonomists might help to improve the overall system. After considering basic differences between helicopters and fixed wing aircraft, the author examines controls, where there are prospects of using miniature hand levers; cockpit vision and displays with particular reference to night and instrument flying; seating and vibration where the effects of protective clothing and harnesses are considered; and cabin noise from the engine, transmission and intercom systems. Finally, he assesses pilot activity using cine film techniques for different types of flight.

  16. 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.

  17. Helicopter Acoustics

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Exterior and interior noise problems are addressed both from the physics and engineering as well as the human factors point of view. The role of technology in closing the gap between what the customers and regulating agencies would like to have and what is available is explored. Noise regulation concepts, design, operations and testing for noise control, helicopter noise prediction, and research tools and measurements are among the topics covered.

  18. Experimental Analysis of Steady-State Maneuvering Effects on Transmission Vibration Patterns Recorded in an AH-1 Cobra Helicopter

    NASA Technical Reports Server (NTRS)

    Huff, Edward M.; Dzwonczyk, Mark; Norvig, Peter (Technical Monitor)

    2000-01-01

    Flight experiment was designed primarily to determine the extent to which steady-state maneuvers influence characteristic vibration patterns measured at the input pinion and output annulus gear locations of the main transmission. If results were to indicate that maneuvers systematically influence vibration patterns, more extensive studies would be planned to explore the response surface. It was also designed to collect baseline data for comparison with experimental data to be recorded at a later date from test stands at Glenn Research Center. Finally, because this was the first vibration flight study on the Cobra aircraft, considerable energy was invested in developing an in-flight recording apparatus, as well as exploring acceleration mounting methods, and generally learning about the overall vibratory characteristics of the aircraft itself.

  19. Fabricated Helicopter Transmission Housing Analysis

    DTIC Science & Technology

    1975-01-01

    This program was conducted for the Military Operations Technology Division under the technical management of Hr. L. Thomas Mazza, Technology Applications...Data Xritred) Uncl ssified .UIJRITY -’.ASSIFICA ’.Wi OF THIS PAGE(Wen Date Entered) materials, analytical methods, and fabrication tecniques . The

  20. Summary of drive-train component technology in helicopters

    NASA Technical Reports Server (NTRS)

    Weden, G. J.; Coy, J. J.

    1984-01-01

    A review of current helicopters was conducted to determine the technology in the drive-train systems. The design features are highlighted including reliability characteristics in transmission systems for the OH-58, UH-1, CH-47, and UH-60 helicopters. In addition, trade-offs involving cost, reliability and life are discussed.

  1. Gears and Power Transmission Systems for Helicopters and Turboprops; Conference Proceedings: Propulsion and Energetics Panel Symposium (64th) Held at Lisbon, Portugal on 8-12 October 1984.

    DTIC Science & Technology

    1985-01-01

    double row bearings are used in planetary gear supports for their ability to withstand misalignments imposed by offset loads on the planet carrier...13 a similar study was done for a typical planetary gear set such as found in a turboprop or helicopter reduction gear stage. The study was done for...in a single stage are not common. The order of weights from lightest to heaviest (for equal gear ratios) is planetary , parallel axis, spiral bevel

  2. 77 FR 18970 - Airworthiness Directives; Bell Helicopter Textron Canada Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-29

    ... Directives; Bell Helicopter Textron Canada Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... (AD) for the Bell Helicopter Textron Canada Limited (BHTC) Model 407 helicopters. This proposed AD is... Helicopter Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4, telephone (450)...

  3. Helicopter Handling Qualities

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Helicopters are used by the military and civilian communities for a variety of tasks and must be capable of operating in poor weather conditions and at night. Accompanying extended helicopter operations is a significant increase in pilot workload and a need for better handling qualities. An overview of the status and problems in the development and specification of helicopter handling-qualities criteria is presented. Topics for future research efforts by government and industry are highlighted.

  4. Small Business Innovations (Helicopters)

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The amount of engine power required for a helicopter to hover is an important, but difficult, consideration in helicopter design. The EHPIC program model produces converged, freely distorted wake geometries that generate accurate analysis of wake-induced downwash, allowing good predictions of rotor thrust and power requirements. Continuum Dynamics, Inc., the Small Business Innovation Research (SBIR) company that developed EHPIC, also produces RotorCRAFT, a program for analysis of aerodynamic loading of helicopter blades in forward flight. Both helicopter codes have been licensed to commercial manufacturers.

  5. Helicopter-based live-line work. Volume 1, Helicopter platform work between phases: Final report

    SciTech Connect

    Gela, G.

    1993-06-01

    This report presents experimental data on tests of a configuration consisting of a helicopter between two energized phases (for AC and switching surge) or poles (for DC). The configuration is that related to live-line work from a hovering helicopter. The McDonnell Douglas 500 Series helicopter was used for the tests. All tests were performed with phase-to-phase, or pole-to-pole energization. For AC tests, proper relationship between the phase-to-ground voltages and the phase-to-phase voltage was maintained by energizing the experimental setup from a balanced 3-{phi} AC source. For DC tests, one pole was energized with positive DC voltage to ground, while the other pole was energized with negative DC voltage to ground. For switching surge tests, a surge of positive polarity and a specific peak voltage magnitude was applied to one phase while a surge of negative polarity and the same peak voltage Magnitude was simultaneously applied to the other phase, resulting in {alpha} = 0.5 ({alpha} is the ratio between negative and total surge). In the research program, four conditions were investigated, namely helicopter operating versus not operating, and helicopter bonded to one phase or pole versus not bonded. Results from this research show effects of the rotating main rotor blade of the helicopter, effect of the position of the electrically floating helicopter in the phase-to-phase or pole-to-pole gap, effects of the mannequin, importance of the polarity of the DC poles and switching surges, and effects of inclement weather such as rain. The overall conclusion of this research is that the phase-to-phase or pole-to-pole spacings that cause sparkover with the helicopter between phases (poles) were always significantly smaller than the typical spacings on actual existing overhead transmission lines of the corresponding voltage rating.

  6. Helicopter simulator qualification

    NASA Technical Reports Server (NTRS)

    Hampson, Brian

    1992-01-01

    CAE has extensive experience in building helicopter simulators and has participated in group working sessions for fixed-wing advisory circulars. Against this background, issues that should be addressed in establishing helicopter approval criteria were highlighted. Some of these issues are not immediately obvious and may, indeed, be more important than the criteria a themselves.

  7. The RMAX Helicopter UAV

    DTIC Science & Technology

    2007-11-02

    7 SYSTEM CONFIGURATION..................................8 OBSERVATION FLIGHT AT ERUPTING VOLCANO , MT. USU...autonomous flight control system. Because our autonomous, unmanned helicopter has succeeded in observation roles at erupting volcanoes , the Japanese...saving devices. In April 2000, we had our GPS-based autonomous helicopter play an observation role at an erupting volcano . This is the first time in

  8. Helicopter human factors

    NASA Technical Reports Server (NTRS)

    Hart, Sandra G.

    1988-01-01

    The state-of-the-art helicopter and its pilot are examined using the tools of human-factors analysis. The significant role of human error in helicopter accidents is discussed; the history of human-factors research on helicopters is briefly traced; the typical flight tasks are described; and the noise, vibration, and temperature conditions typical of modern military helicopters are characterized. Also considered are helicopter controls, cockpit instruments and displays, and the impact of cockpit design on pilot workload. Particular attention is given to possible advanced-technology improvements, such as control stabilization and augmentation, FBW and fly-by-light systems, multifunction displays, night-vision goggles, pilot night-vision systems, night-vision displays with superimposed symbols, target acquisition and designation systems, and aural displays. Diagrams, drawings, and photographs are provided.

  9. Research requirements to reduce civil helicopter life cycle cost

    NASA Technical Reports Server (NTRS)

    Blewitt, S. J.

    1978-01-01

    The problem of the high cost of helicopter development, production, operation, and maintenance is defined and the cost drivers are identified. Helicopter life cycle costs would decrease by about 17 percent if currently available technology were applied. With advanced technology, a reduction of about 30 percent in helicopter life cycle costs is projected. Technological and managerial deficiencies which contribute to high costs are examined, basic research and development projects which can reduce costs include methods for reduced fuel consumption; improved turbine engines; airframe and engine production methods; safety; rotor systems; and advanced transmission systems.

  10. Load Distribution in Transmissions "Split"

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.; Delgado, Irebert R.

    1998-01-01

    The transmission system of a helicopter must meet particularly critical requirements. It must transmit engine power to the rotor, at the same time ensuring a typical speed reduction of 60 to 1. It must also be safe, reliable, light, and reach a high level of performance while, at the same time, it must produce few vibrations and little noise. Helicopter transmissions have achieved high-level performances thanks to the combination of analyses, experiments, and the application of practical field experience. However, the new generation of helicopters will require transmission systems that are even safer, lighter, less noisy, and more reliable.

  11. Multimission helicopter cockpit displays

    NASA Astrophysics Data System (ADS)

    Terry, William S.; Terry, Jody K.; Lovelace, Nancy D.

    1996-05-01

    A new operator display subsystem is being incorporated as part of the next generation United States Navy (USN) helicopter avionics system to be integrated into the multi-mission helicopter (MMH) that replaces both the SH-60B and the SH-60F in 2001. This subsystem exploits state-of-the-art technology for the display hardware, the display driver hardware, information presentation methodologies, and software architecture. Both of the existing SH-60 helicopter display systems are based on monochrome CRT technology; a key feature of the MMH cockpit is the integration of color AMLCD multifunction displays. The MMH program is one of the first military programs to use modified commercial AMLCD elements in a tactical aircraft. This paper presents the general configuration of the MMH cockpit and multifunction display subsystem and discusses the approach taken for presenting helicopter flight information to the pilots as well as presentation of mission sensor data for use by the copilot.

  12. Occupational Survey Report. Helicopter Maintenance

    DTIC Science & Technology

    1994-03-01

    helicopters I-D53 Oversee helicopter inspectim or maintance activities during cross-country missions on H- I B15 0014 H-1Maian (Continued) H383 Remove or...Plan maintmeance or inspections of helicopters E95 Comdinate estimated times in commission (ETICs) of maintance jobs with job control A19 Plan work

  13. Helicopter simulator standards

    NASA Technical Reports Server (NTRS)

    Boothe, Edward M.

    1992-01-01

    The initial advisory circular was produced in 1984 (AC 120-XX). It was not finalized, however, because the FAR's for pilot certification did not recognize helicopter simulators and, therefore, permitted no credit for their use. That is being rectified, and, when the new rules are published, standards must be available for qualifying simulators. Because of the lack of a data base to support specification of these standards, the FAA must rely on the knowledge of experts in the simulator/training industry. A major aim of this workshop is to form a working group of these experts to produce a set of standards for helicopter training simulators.

  14. Noise reduction experience at Hughes Helicopter, Inc.

    NASA Technical Reports Server (NTRS)

    Janakiram, D. S.

    1982-01-01

    Noise reduction is mostly limited to light helicopters whose noise signature is dominated by their tail rotors. It is primarily hardware oriented. Well known noise reduction techniques such as reduction of rotor speeds with an accompanying increase in solidity to maintain performance, engine noise reduction with the use of exhaust mufflers, and acoustic blanketing of transmission and engine compartment are used. The concept of blade phasing as a means of reducing tail rotor noise is also used. Engine noise (exhaust noise), power train noise and airframe noise becomes important at low rotor tip speeds and means must be found to reduce these noise sources if further noise reductions are desired. The use of a special test rig aids in isolating the various noise sources and arriving at the penalties (performance or payload) involved in quieting them. Significant noise reduction are achieved for the light helicopter with minimum performance or weight penalties because of the dominance of a single noise source (the tail rotor).

  15. Transmission

    SciTech Connect

    Sugano, K.

    1988-12-27

    A transmission is described which consists of: an input shaft; an output shaft; a first planetary gear set including a first sun gear selectively connectable by a first clutch to the input shaft, a first carrier selectively connectable by a second clutch to the input shaft and a first ring gear connected to the output shaft. The first sun gear selectively held stationary by a first brake, the first carrier is allowed to rotate in the same forward direction as the input shaft when the second clutch is engaged, but prevented from rotating in a reverse direction opposite to the forward direction by a first one-way clutch, the first carrier being selectively held stationary by a second brake; a second planetary gear set including a second sun gear connected to the input shaft, a second carrier connected to the first ring gear and also the the output shaft, and a second ring gear.

  16. Combat Rescue Helicopter (CRH)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-479 Combat Rescue Helicopter (CRH) As of FY 2017 President’s Budget Defense Acquisition...Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be Determined TY - Then Year UCR

  17. The Focke Helicopter

    NASA Technical Reports Server (NTRS)

    Focke, H; Kruger, K B

    1938-01-01

    This report presents some of the problems concerning tests of helicopters, such as forced landings, controllability and stability, general safety, piloting maneuvers, performance, servicing, and the production of lift of a propeller. Test flights are described including a 67.67 mph flight by Hanna Reitsch.

  18. 29 CFR 1926.958 - External load helicopters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false External load helicopters. 1926.958 Section 1926.958 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Power Transmission and Distribution §...

  19. Investigation of Current Methods to Identify Helicopter Gear Health

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Lewicki, David G.; Le, Dy D.

    2007-01-01

    This paper provides an overview of current vibration methods used to identify the health of helicopter transmission gears. The gears are critical to the transmission system that provides propulsion, lift and maneuvering of the helicopter. This paper reviews techniques used to process vibration data to calculate conditions indicators (CI s), guidelines used by the government aviation authorities in developing and certifying the Health and Usage Monitoring System (HUMS), condition and health indicators used in commercial HUMS, and different methods used to set thresholds to detect damage. Initial assessment of a method to set thresholds for vibration based condition indicators applied to flight and test rig data by evaluating differences in distributions between comparable transmissions are also discussed. Gear condition indicator FM4 values are compared on an OH58 helicopter during 14 maneuvers and an OH58 transmission test stand during crack propagation tests. Preliminary results show the distributions between healthy helicopter and rig data are comparable and distributions between healthy and damaged gears show significant differences.

  20. Investigation of Current Methods to Identify Helicopter Gear Health

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Lewicki, David G.; Le, Dy D.

    2007-01-01

    This paper provides an overview of current vibration methods used to identify the health of helicopter transmission gears. The gears are critical to the transmission system that provides propulsion, lift and maneuvering of the helicopter. This paper reviews techniques used to process vibration data to calculate conditions indicators (CI's), guidelines used by the government aviation authorities in developing and certifying the Health and Usage Monitoring System (HUMS), condition and health indicators used in commercial HUMS, and different methods used to set thresholds to detect damage. Initial assessment of a method to set thresholds for vibration based condition indicators applied to flight and test rig data by evaluating differences in distributions between comparable transmissions are also discussed. Gear condition indicator FM4 values are compared on an OH58 helicopter during 14 maneuvers and an OH58 transmission test stand during crack propagation tests. Preliminary results show the distributions between healthy helicopter and rig data are comparable and distributions between healthy and damaged gears show significant differences.

  1. Utility of Helicopter Rotor Reflections at HF

    DTIC Science & Technology

    1972-12-29

    Vesuvius AE 15 Ammunition Helicopter platform Mount Katmai AE 16 Ammunition Helicopter platform Great Sitkin AE 17 Ammunition Helicopter platform Diamond...carried Mount Whitney LCC 20 Amphibious command Utility helicopter carried Eldorado LCC 11 Amphibious command Utility helicopter carried Iwo Jima LPH...Barbara AE 28 Special minesweeper Mount Hood AE 29 Special minesweeper Suribachi AE 21 Ammunition Helicopter platform Mauna Kea AE 22 Ammunition

  2. Helicopter external noise requirements: FAA perspective

    NASA Technical Reports Server (NTRS)

    Foster, C. R.

    1978-01-01

    Enactment of helicopter noise certification standards for the control of noise impact contributing to community annoyance is considered in terms of the development of helicopters as an environmentally compatible air transportation mode. Increased use of helicopters for commercial applications and public awareness of aircraft noise are cited as factors making development of helicopter noise standards necessary both for the protection of the environmental interest of the community and to ensure the orderly growth of the helicopter industry itself. Noise sources, technology trends in helicopter design, and design concepts to control helicopter noise are discussed along with the regulatory background and specific helicopter regulatory concepts.

  3. OH-58 Helicopter Transmission Failure Analysis

    DTIC Science & Technology

    1976-01-01

    AD-A956 125 ^"»^ s DTIC ELECTE N0V9 1992 1. Report No. ^ NASAJJMrX-71867 2. Government Acceision No. 4 . Title and Subtitle OH-58...TEST PROCEDURE The OH-58 gearbox was placed in the Corpus Christi Army Depot OH-58 test stand after being fully instrumented (fig. 3). Figures 4 ...running time also gave additional break-in time for the new gearbox. The gearbox was subsequently operated at 32 different test conditions with

  4. Helicopter blade tips

    NASA Technical Reports Server (NTRS)

    Lyothier, R.

    1983-01-01

    Methods of improving helicopter performance and vibration level by proper shaping of helicopter blade tips are considered. The principle involved consists of reducing the extent of the supersonic zone above the advancing tip and of the turbulent interaction. For stationary and advancing flight, the influence of the rotor and the problems posed by blade tips are reviewed. The theoretical methods of dealing with the two types of flight are briefly stated, and the experimental apparatus is described, including model triple and quadruple rotors. Different blade tip shapes are shown and briefly discussed. The theoretical results include an advancing speed of 309 km/H and a blade tip rotational speed of 215 m/s. The experimental values are advancing speed of 302 km/h and blade tip Mach number 0.86 for both types of rotors.

  5. Helicopter Visual Aid System

    NASA Technical Reports Server (NTRS)

    Baisley, R. L.

    1973-01-01

    The results of an evaluation of police helicopter effectiveness revealed a need for improved visual capability. A JPL program developed a method that would enhance visual observation capability for both day and night usage and demonstrated the feasibility of the adopted approach. This approach made use of remote pointable optics, a display screen, a slaved covert searchlight, and a coupled camera. The approach was proved feasible through field testing and by judgement against evaluation criteria.

  6. Apollo 10 Helicopter Recovery

    NASA Technical Reports Server (NTRS)

    1969-01-01

    A Navy helicopter arrivies to recover the Apollo 10 astronauts, seen entering a life raft, as the Command Module 'Charlie Brown' floats in the South Pacific. U.S. Navy underwater demolition team swimmers assist in the recovery operations. Splashdown occurred at 11:53 a.m., May 26, 1969, about 400 miles east of American Samoa. Note that in this photo the divers have attached a flotation collar to the spacecraft.

  7. Operational Helicopter Aviation Medicine

    DTIC Science & Technology

    1978-12-01

    acoustic stimuli travelling through the system to the inner ear. HEARING PROTECTOR AND VOICE COMMUNICATIONS SYSTEMS EFFECTS The humar auditory system just...equipment, communication noise, aircrew hearing loss, and weapons impulse noise. Helicopter Safety and Crashworthiness covered crash injury analysis...protect visual and auditory performance while performing aircrew duties were also pre- sented. A summ. ry of the excellent work presented supported the

  8. 77 FR 36131 - Airworthiness Directives; Enstrom Helicopter Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-18

    ...-28, 480, and 480B helicopters to add another trim relay to the applicability and to revise the modification instructions. This AD is prompted by the discovery that another part- numbered trim relay...-28F, 280C, 280F, 280FX, TH-28, 480, and 480B helicopters with a trim relay, part-number (P/N)...

  9. 77 FR 52264 - Airworthiness Directives; Hughes Helicopters, Inc., and McDonnell Douglas Helicopter Systems...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

    ... Directives; Hughes Helicopters, Inc., and McDonnell Douglas Helicopter Systems (Type Certificate Currently... proposed AD, contact MD Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop... Airworthiness Directive (AD): Hughes Helicopters Inc., and McDonnel Douglas Helicopter Systems (Type...

  10. Helicopter simulation: Making it work

    NASA Technical Reports Server (NTRS)

    Payne, Barry

    1992-01-01

    The opportunities for improved training and checking by using helicopter simulators are greater than they are for airplane pilot training. Simulators permit the safe creation of training environments that are conducive to the development of pilot decision-making, situational awareness, and cockpit management. This paper defines specific attributes required in a simulator to meet a typical helicopter operator's training and checking objectives.

  11. Recent European Developments in Helicopters

    NASA Technical Reports Server (NTRS)

    1921-01-01

    Descriptions are given of two captured helicopters, one driven by electric power, the other by a gasoline engine. An account is given of flight tests of the gasoline powered vehicle. After 15 successful flight tests, the gasoline powered vehicle crashed due to the insufficient thrust. Also discussed here are the applications of helicopters for military observations, for meteorological work, and for carrying radio antennas.

  12. Helicopter Acoustics, part 2. [conferences

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Exterior and interior helicopter noise problems are addressed from the physics and engineering as well as the human factors point of view. Noise regulation concepts, human factors and criteria, rotor noise generation and control, design, operations and testing for noise control, helicopter noise prediction, and research tools and measurements are covered.

  13. Helicopter discrimination apparatus for the murine radar

    DOEpatents

    Webb, Jr., John G.; Gray, Roger M.

    1977-01-01

    A helicopter discrimination apparatus for a radar utilizing doppler filtering to discriminate between a missile and ground clutter. The short duration of the doppler filter pulses which are emitted by helicopter rotor blades are processed to prevent false alarms, thus allowing the radar-protected helicopter to operate in formation with other helicopters while maintaining protection against infra-red-seeking missiles.

  14. Helicopter Human Factors

    NASA Technical Reports Server (NTRS)

    Hart, Sandra G.; Sridhar, Banavar (Technical Monitor)

    1995-01-01

    Even under optimal conditions, helicopter flight is a most demanding form of human-machine interaction, imposing continuous manual, visual, communications, and mental demands on pilots. It is made even more challenging by small margins for error created by the close proximity of terrain in NOE flight and missions flown at night and in low visibility. Although technology advances have satisfied some current and proposed requirements, hardware solutions alone are not sufficient to ensure acceptable system performance and pilot workload. However, human factors data needed to improve the design and use of helicopters lag behind advances in sensor, display, and control technology. Thus, it is difficult for designers to consider human capabilities and limitations when making design decisions. This results in costly accidents, design mistakes, unrealistic mission requirements, excessive training costs, and challenge human adaptability. NASA, in collaboration with DOD, industry, and academia, has initiated a program of research to develop scientific data bases and design principles to improve the pilot/vehicle interface, optimize training time and cost, and maintain pilot workload and system performance at an acceptable level. Work performed at Ames, and by other research laboratories, will be reviewed to summarize the most critical helicopter human factors problems and the results of research that has been performed to: (1) Quantify/model pilots use of visual cues for vehicle control; (2) Improve pilots' performance with helmet displays of thermal imagery and night vision goggles for situation awareness and vehicle control; (3) Model the processes by which pilots encode maps and compare them to the visual scene to develop perceptually and cognitively compatible electronic map formats; (4) Evaluate the use of spatially localized auditory displays for geographical orientation, target localization, radio frequency separation; (5) Develop and flight test control

  15. World helicopter market study

    NASA Technical Reports Server (NTRS)

    Cleary, B.; Pearson, R. W.; Greenwood, S. W.; Kaplan, L.

    1978-01-01

    The extent of the threat to the US helicopter industry posed by a determined effort by foreign manufacturers, European companies in particular, to supply their own domestic markets and also to penetrate export markets, including the USA is assessed. Available data on US and world markets for civil and military uses are collated and presented in both graphic and tabular form showing the past history of production and markets and, where forecasts are available, anticipated future trends. The data are discussed on an item-by-item basis and inferences are drawn in as much depth as appears justified.

  16. Helicopter high gain control

    NASA Technical Reports Server (NTRS)

    Cunningham, T. B.; Nunn, E. C.

    1979-01-01

    High gain control is explored through a design study of the CH-47B helicopter. The plans are designed to obtain the maximum bandwidth possible given the hardware constraints. Controls are designed with modal control theory to specific bandwidths and closed loop mode shapes. Comparisons are made to an earlier complementary filter approach. Bandwidth improvement by removal of limitations is explored in order to establish hardware and mechanization options. Improvements in the pitch axis control system and in the rate gyro sensor noise characteristics in all axes are discussed. The use of rotor state feedback is assessed.

  17. Medical helicopters: carbon monoxide risk?

    PubMed

    Poulton, T J

    1987-02-01

    Carbon monoxide exposure of medical personnel working beneath the turning rotor of a medical helicopter appeared to cause mild clinical illness. We measured the carbon monoxide levels found in various locations beneath the rotor of a jet helicopter under two different conditions. Carbon monoxide levels ranged from 8-76 ppm depending on location of sampling and speed of operation of the engine. This level of carbon monoxide is potentially a problem, as is the inhalation of jet fuel vapor, when working beneath the rotors of an operating helicopter.

  18. Helicopter human factors research

    NASA Technical Reports Server (NTRS)

    Nagel, David C.; Hart, Sandra G.

    1988-01-01

    Helicopter flight is among the most demanding of all human-machine integrations. The inherent manual control complexities of rotorcraft are made even more challenging by the small margin for error created in certain operations, such as nap-of-the-Earth (NOE) flight, by the proximity of the terrain. Accident data recount numerous examples of unintended conflict between helicopters and terrain and attest to the perceptual and control difficulties associated with low altitude flight tasks. Ames Research Center, in cooperation with the U.S. Army Aeroflightdynamics Directorate, has initiated an ambitious research program aimed at increasing safety margins for both civilian and military rotorcraft operations. The program is broad, fundamental, and focused on the development of scientific understandings and technological countermeasures. Research being conducted in several areas is reviewed: workload assessment, prediction, and measure validation; development of advanced displays and effective pilot/automation interfaces; identification of visual cues necessary for low-level, low-visibility flight and modeling of visual flight-path control; and pilot training.

  19. Helicopter noise regulations: An industry perspective

    NASA Technical Reports Server (NTRS)

    Wagner, R. A.

    1978-01-01

    A review of helicopter noise measurement programs and noise reduction/economic studies of FAA is given along with a critique of a study which addresses the economic impact of noise reduction on helicopter noise. Modification of several helicopters to reduce noise and demonstrate the economic impact of the application of the current state-of-the-art technology is discussed. Specific helicopters described include Boeing Vertol 347 Helicopter, Hughes OH-6 Helicopter, and Hughes 269C Helicopter. Other topics covered include: (1) noise trends and possible noise limits; (2) accuracy of helicopter noise prediction techniques; (3) limited change possibilities of derivatives; and (4) rotor impulsive noise. The unique operational capabilities of helicopters and the implications relative to noise regulations and certification are discussed.

  20. Vertebral pain in helicopter pilots

    NASA Technical Reports Server (NTRS)

    Auffret, R.; Delahaye, R. P.; Metges, P. J.; VICENS

    1980-01-01

    Pathological forms of spinal pain engendered by piloting helicopters were clinically studied. Lumbalgia and pathology of the dorsal and cervical spine are discussed along with their clinical and radiological signs and origins.

  1. Tests Of Helicopter Control System

    NASA Technical Reports Server (NTRS)

    Hilbert, Kathryn B.; Lebacqz, J. Victor; Hindson, William S.

    1988-01-01

    Advanced control systems being developed for rotorcraft. Report discusses aspects of development of multivariable, explicit-model-following control system for CH-47B fly-by-wire helicopter. Project part of recent trend toward use of highly-augmented, high-gain flight-control systems to assist pilots of military helicopters in performance of demanding tasks and to improve handling qualities of aircraft.

  2. Rotorcraft transmission

    NASA Technical Reports Server (NTRS)

    Coy, John J.

    1987-01-01

    The NASA Lewis Research Center and the U.S. Army Aviation Systems Command share an interest in advancing the technology for helicopter propulsion systems. In particular, this presentation outlines that portion of the program that applies to the drive train and its various mechanical components. The major goals of the program are to increase the life, reliability, and maintainability; reduce the weight, noise, and vibration; and maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for transmission research in the future is presented.

  3. 77 FR 5425 - Airworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ... Helicopter Textron Canada Limited Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... the Bell Helicopter Textron Canada Limited (BHTC) Model 427 helicopters. This proposed AD is prompted... Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4, telephone (450) 437-2862 or (800)...

  4. The evolution of helicopters

    NASA Astrophysics Data System (ADS)

    Chen, R.; Wen, C. Y.; Lorente, S.; Bejan, A.

    2016-07-01

    Here, we show that during their half-century history, helicopters have been evolving into geometrically similar architectures with surprisingly sharp correlations between dimensions, performance, and body size. For example, proportionalities emerge between body size, engine size, and the fuel load. Furthermore, the engine efficiency increases with the engine size, and the propeller radius is roughly the same as the length scale of the whole body. These trends are in accord with the constructal law, which accounts for the engine efficiency trend and the proportionality between "motor" size and body size in animals and vehicles. These body-size effects are qualitatively the same as those uncovered earlier for the evolution of aircraft. The present study adds to this theoretical body of research the evolutionary design of all technologies [A. Bejan, The Physics of Life: The Evolution of Everything (St. Martin's Press, New York, 2016)].

  5. A new helicostat from SNIAS helicopter division

    NASA Technical Reports Server (NTRS)

    Morisset, J.

    1977-01-01

    The Helicostat was described as a helicopter in which the vehicle weight is nullified by two balloons arranged in a catamaran fashion. Development of such a vehicle is discussed, and various uses for these helicopters are summarized.

  6. Helicopter External Load Acquisition Technology Investigation.

    DTIC Science & Technology

    1980-12-01

    101st Airborne Division, Fort Campbell, Ky. Evergreen Helicopters, McMinnville , Oregon The Army Technical Representative for the program was Mr. Richard...commercial helicopter operator, Evergreen Helicopters, McMinnville , Oregon, to obtain additional data on commercial solutions to external load acquisition

  7. Helicopter Aircrew Training Using Fused Reality

    DTIC Science & Technology

    2006-06-01

    RTO-MP-HFM-136 27 - 1 Helicopter Aircrew Training Using Fused Reality Dr. Ed Bachelder Systems Technology Inc. 13766 Hawthorne Blvd...applied to training helicopter aircrew personnel using a prototype simulator, the Prototype Aircrew Virtual Environment Training (PAVET) System...cabin) pixels using blue screen imaging techniques. This bitmap is overlaid on a virtual environment, and sent Bachelder, E. (2006) Helicopter Aircrew

  8. 29 CFR 1926.551 - Helicopters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... activating device so designed and installed as to prevent inadvertent operation. In addition, these cargo... allowed to approach within 50 feet of the helicopter when the rotor blades are turning. (p) Approaching helicopter. Whenever approaching or leaving a helicopter with blades rotating, all employees shall remain...

  9. 29 CFR 1926.551 - Helicopters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activating device so designed and installed as to prevent inadvertent operation. In addition, these cargo... allowed to approach within 50 feet of the helicopter when the rotor blades are turning. (p) Approaching helicopter. Whenever approaching or leaving a helicopter with blades rotating, all employees shall remain...

  10. 29 CFR 1926.551 - Helicopters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... activating device so designed and installed as to prevent inadvertent operation. In addition, these cargo... allowed to approach within 50 feet of the helicopter when the rotor blades are turning. (p) Approaching helicopter. Whenever approaching or leaving a helicopter with blades rotating, all employees shall remain...

  11. 29 CFR 1926.551 - Helicopters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... activating device so designed and installed as to prevent inadvertent operation. In addition, these cargo... allowed to approach within 50 feet of the helicopter when the rotor blades are turning. (p) Approaching helicopter. Whenever approaching or leaving a helicopter with blades rotating, all employees shall remain...

  12. 29 CFR 1926.551 - Helicopters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... activating device so designed and installed as to prevent inadvertent operation. In addition, these cargo... allowed to approach within 50 feet of the helicopter when the rotor blades are turning. (p) Approaching helicopter. Whenever approaching or leaving a helicopter with blades rotating, all employees shall remain...

  13. Investigating Flight with a Toy Helicopter

    ERIC Educational Resources Information Center

    Liebl, Michael

    2010-01-01

    Flight fascinates people of all ages. Recent advances in battery technology have extended the capabilities of model airplanes and toy helicopters. For those who have never outgrown a childhood enthusiasm for the wonders of flight, it is possible to buy inexpensive, remotely controlled planes and helicopters. A toy helicopter offers an opportunity…

  14. Method for Studying Helicopter Longitudinal Maneuver Stability

    NASA Technical Reports Server (NTRS)

    Amer, Kenneth B

    1954-01-01

    A theoretical analysis of helicopter maneuver stability is made and the results are compared with experimental results for both a single and a tandem rotor helicopter. Techniques are described for measuring in flight the significant stability derivatives for use with the theory to aid in design studies of means for achieving marginal maneuver stability for a prototype helicopter.

  15. Improvements in Spiral-Bevel Gears to Reduce Noise and Increase Strength

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.; Handschuh, Robert F.; Henry, Zachary S.; Litvin, Faydor L.

    1994-01-01

    Advanced-design spiral-bevel gears were tested in an OH-58D helicopter transmission using the NASA 500 hp Helicopter Transmission Test Stand. Four different gear designs were tested. The four designs tested were the current design of the OH-58D transmission, a higher-strength design the same as the current but with an increased fillet radius to reduce gear tooth bending stress, and two versions of a lower-noise design the same as the high-strength but with modified tooth geometry to reduce transmission error and noise. Noise, vibration, and tooth strain tests were performed and significant gear stress and noise reductions were achieved.

  16. Civil helicopter flight research. [for CH-53 helicopter

    NASA Technical Reports Server (NTRS)

    Snyder, W. J.; Schoultz, M. B.

    1976-01-01

    The paper presents a description of the NASA CH-53 Civil Helicopter Research Aircraft and discusses preliminary results of the aircraft flight research performed to evaluate factors and requirements for future helicopter transport operations. The CH-53 equipped with a 16-seat airline-type cabin and instrumented for flight research studies in noise, vibration, handling qualities, passenger acceptance, fuel utilization, terminal area maneuvers, and gust response. Predicted fuel usage for typical short-haul missions is compared with actual fuel use. Pilot ratings for an IFR handling quality task for three levels of stability augmentation are presented, and the effects of internal noise, vibration, and motion on passenger acceptance are discussed. Future planned CH-53 flight research within the Civil Helicopter Technology Program is discussed.

  17. [Importance of helicopter rescue].

    PubMed

    Hofer, G; Voelckel, W G

    2014-03-01

    Helicopter emergency medical service (HEMS) have become a main part of prehospital emergency medical services over the last 40 years. Recently, an ongoing discussion about financial shortage and personal shortcomings question the role of cost-intensive air rescue. Thus, the value of HEMS must be examined and discussed appropriately. Since the number of physician-staffed ground ambulances may decrease due to the limited availability of qualified physicians, HEMS may fill the gap. In addition patient transfer to specialized hospitals will require an increasing number of air transports in order to minimize prehospital time. The higher risk ratio for HEMS missions when compared with ground rescue requires a rigorous quality management system. When it comes to missions in remote and exposed areas, the scope of medical treatment must be adjusted to the individual situation. Medical competence is key in order to balance guideline compliant or maximal care versus optimal care characterized as a mission-specific, individualized emergency care concept. Although, medical decision making and treatment is typically based on the best scientific evidence, personal skills, competence, and the mission scenario will determine the scope of interventions suitable to improve outcome. Thus, the profile of requirements for the HEMS medical crew is high.

  18. [Back ache in helicopter pilots].

    PubMed

    Colak, S; Jovelić, S; Manojlović, J

    1992-01-01

    Due to low back pain (LBP) and harmful effects of flying, questionnaires were sent to 71 helicopter pilots of the experimental group, 22 mechanics helicopter flyers and to the control group of 28 air-traffic controllers. The prevalence of LBP was the highest in helicopter pilots, then in helicomechanics and air-traffic controllers (53%, 50% and 36%). Effects of exposure to vibration, body posture and working load have not contributed significantly to the occurrence of LBP. LBP has not lead to an important difference in the strength of the back musculature, body mass index and spondylosis, that is, scoliosis. The necessity of further study of LBP and maintaining of specific preventive measures are indicated.

  19. Annoyance of helicopter impulsive noise

    NASA Technical Reports Server (NTRS)

    Dambra, F.; Damongeot, A.

    1978-01-01

    Psychoacoustic studies of helicopter impulsive noise were conducted in order to qualify additional annoyance due to this feature and to develop physical impulsiveness descriptors to develop impulsivity correction methods. The currently proposed descriptors and methods of impulsiveness correction are compared using a multilinear regression analysis technique. It is shown that the presently recommended descriptor and correction method provides the best correlation with the subjective evaluations of real helicopter impulsive noises. The equipment necessary for data processing in order to apply the correction method is discussed.

  20. Condition based machinery maintenance (helicopter fault detection), phase 1

    NASA Astrophysics Data System (ADS)

    Brotherton, T. W.; Pollard, T. G.

    1993-01-01

    A problem of current interest to the Navy is the automatic detection and classification of faults in mechanical systems such as the transmissions, gearboxes, and bearings of helicopters. The problem is important for both economic and safety reasons. Using automated fault detection and classification, machinery repair can be undertaken as needed and can prevent catastrophic failure. This condition-based maintenance approach is more efficient and cost-effective than the use of predetermined maintenance schedules. Additionally, automated fault detection and classification systems can alert machinery operators, such as helicopter pilots, of the onset of a mechanical problem, thus allowing the pilot to take precautions, such as landing the aircraft, before a potentially catastrophic failure occurs.

  1. 78 FR 27867 - Airworthiness Directives; MD Helicopters Inc. Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-13

    ..., leading to vibration, loss of tail rotor pitch control, and subsequent loss of tail rotor and helicopter... from cracking and separating from the blade, leading to an unbalanced condition, vibration, loss of...) separating from the tail rotor blade, leading to an unbalanced condition, vibration, loss of tail rotor...

  2. 78 FR 65180 - Airworthiness Directives; MD Helicopters, Inc., Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-31

    ... actions are intended to prevent a pitch horn from cracking, leading to vibration, loss of tail rotor pitch... condition, vibration, loss of tail rotor pitch control, and loss of directional control of the helicopter... (pitch horn) separating from the tail rotor blade, leading to an unbalanced condition, vibration, loss...

  3. 78 FR 65195 - Airworthiness Directives; MD Helicopters, Inc. (MDHI) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-31

    ... rotor blade (MRB) retention bolts (bolts) installed. This AD requires a daily check of the position of... other helicopters of the same type designs and that air safety and the public interest require adopting... (ASB SB900-116). ASB SB900-116 specifies a repetitive check of the blade retention bolts, part...

  4. 77 FR 23638 - Airworthiness Directives; Bell Helicopter Textron, Incorporated Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-20

    ..., and the AD ] applicability needs to be expanded to include additional grips similar in design, as well... rotor blade, and subsequent loss of control of the helicopter. DATES: We must receive comments on this... damage to the blade, blade bolt bore, or buffer pad tang surface were found in the two cracked...

  5. 77 FR 5427 - Airworthiness Directives; Bell Helicopter Textron, Inc., Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ... creating a component history card or equivalent record and begin counting and recording the number of... Internet at http://www.regulations.gov or in person at the Docket Operations Office between 9 a.m. and 5 p... for the specified Bell model helicopters. This proposal would require creating a component...

  6. 77 FR 68055 - Airworthiness Directives; Bell Helicopter Textron Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ..., and 412CF helicopters. This AD requires a repetitive inspection of the collective lever for a crack, and if there is a crack, before further flight, replacing the collective lever with an airworthy... to detect a crack in the collective lever, which could lead to failure of the collective lever...

  7. 78 FR 18224 - Airworthiness Directives; Robinson Helicopter Company Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA-2012-1088; Directorate Identifier 2012-SW...): 2013-05-15 Robinson Helicopter Company: Amendment 39-17387; Docket No. FAA-2012-1088;...

  8. 78 FR 1730 - Airworthiness Directives; Bell Helicopter Textron Inc. Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-09

    ... 205A, 205A-1, and 205B helicopters with certain starter/generator power cable assemblies (power cable assemblies). This AD requires replacing the power cable assemblies and their associated parts, and performing continuity readings. This AD was prompted by the determination that the power cable assembly...

  9. 77 FR 729 - Airworthiness Directives; Enstrom Helicopter Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-06

    ... certain trim relays to require modifying and testing the lateral and longitudinal cyclic trim actuator..., and 480B helicopters with a trim relay, part-number (P/N) KUP14D55-472, M83536/10-015M, or M83536/10...) and flight tests to determine that the trim relay is working correctly. This AD was prompted...

  10. Helicopter Toy and Lift Estimation

    ERIC Educational Resources Information Center

    Shakerin, Said

    2013-01-01

    A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)

  11. 78 FR 47531 - Airworthiness Directives; Various Restricted Category Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-06

    ... State University); Firefly Aviation Helicopter Services (previously Erickson Air-Crane Co.); California... State University); Firefly Aviation Helicopter Services (previously Erickson Air-Crane Co.); California... Falcon Exporters, Inc. (previously Utah State University); Firefly Aviation Helicopter...

  12. 77 FR 44434 - Airworthiness Directives; Various Restricted Category Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-30

    ... State University); Firefly Aviation Helicopter Services (previously Erickson Air-Crane Co.); California... apply to Arrow Falcon Exporters, Inc. (previously Utah State University); Firefly Aviation Helicopter... Arrow Falcon Exporters, Inc. (previously Utah State University); Firefly Aviation Helicopter...

  13. 78 FR 54792 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-06

    ... (Eurocopter) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed... Model EC225 LP helicopters. This proposed AD would add a new operating limitation that would require increasing the minimum density altitude flight limitation for helicopters without certain...

  14. 75 FR 47197 - Airworthiness Directives; Schweizer Aircraft Corporation (Schweizer) Model 269D Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-05

    ... Housing Blade Containment Shielding Kit on each helicopter. This amendment is prompted by 21 reports of the blades of the oil cooler impeller separating, one of which punctured the engine and transmission... protect the oil cooler from uncontained oil cooler impeller blades that could damage the oil cooler...

  15. Optimal landing of a helicopter in autorotation

    NASA Technical Reports Server (NTRS)

    Lee, A. Y. N.

    1985-01-01

    Gliding descent in autorotation is a maneuver used by helicopter pilots in case of engine failure. The landing of a helicopter in autorotation is formulated as a nonlinear optimal control problem. The OH-58A helicopter was used. Helicopter vertical and horizontal velocities, vertical and horizontal displacement, and the rotor angle speed were modeled. An empirical approximation for the induced veloctiy in the vortex-ring state were provided. The cost function of the optimal control problem is a weighted sum of the squared horizontal and vertical components of the helicopter velocity at touchdown. Optimal trajectories are calculated for entry conditions well within the horizontal-vertical restriction curve, with the helicopter initially in hover or forwared flight. The resultant two-point boundary value problem with path equality constraints was successfully solved using the Sequential Gradient Restoration Technique.

  16. Model predictive formation control of helicopter systems

    NASA Astrophysics Data System (ADS)

    Saffarian, Mehdi

    In this thesis, a robust formation control framework for formation control of a group of helicopters is proposed and designed. The dynamic model of the helicopter has been developed and verified through simulations. The control framework is constructed using two main control schemes for navigation of a helicopter group in three-dimensional (3D) environments. Two schemes are designed to maintain the position of one helicopter with respect to one or two other neighboring members, respectively. The developed parameters can uniquely define the position of the helicopters with respect to each other and can be used for any other aerial and under water vehicles such as airplanes, spacecrafts and submarines. Also, since this approach is modular, it is possible to use it for desired number and form of the group helicopters. Using the defined control parameters, two decentralized controllers are designed based on Nonlinear Model Predictive Control (NMPC) algorithm technique. The framework performance has been tested through simulation of different formation scenarios.

  17. 76 FR 66609 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Model 407 and 427 Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-27

    ... Textron Canada (Bell) Model 407 and 427 Helicopters AGENCY: Federal Aviation Administration, DOT. ACTION... the service information identified in this AD from Bell Helicopter Textron Canada Limited, 12,800 Rue... the helicopter. Transport Canada, the airworthiness authority for Canada, notified the FAA that...

  18. 78 FR 23688 - Airworthiness Directives; Bell Helicopter Textron Canada Inc. Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-22

    ... Textron Canada Inc. Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... Bell Helicopter Textron Canada Inc. (BHT) Model 206A, 206B, and 206L helicopters. This proposed AD... Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4; telephone (450) 437-2862 or (800)...

  19. Documenting helicopter operations from an energy standpoint

    NASA Technical Reports Server (NTRS)

    Davis, S. J.; Stepniewski, W. Z.

    1974-01-01

    Results are presented of a study of the relative and absolute energy consumption of helicopters, including limited comparisons with fixed-wing aircraft, and selected surface transportation vehicles. Additional comparisons were made to determine the level of reduction in energy consumption expected from the application of advanced technologies to the helicopter design and sizing process. It was found that improvements in helicopter consumption characteristics can be accomplished through the utilization of advanced technology to reduce drag, structures weight, and powerplant fuel consumption.

  20. Research On The CH-47B Helicopter

    NASA Technical Reports Server (NTRS)

    Hilbert, Kathryn B.; Tucker, George E.; Chen, Robert T. N.; Fry, Emmett B.; Hindson, William S.

    1988-01-01

    Report describes equipment added to, and research capabilities of CH-47B helicopter. Programmable symbol generator provides display formats for variety of missions - those of vertical-takeoff-and-landing aircraft and helicopters. Powerful general-purpose flight computer in operation. Computer programmable in high-level languages and supports research more efficiently. Flight-control software developed to improve capability of helicopter to perform simulations in flight.

  1. Portable-Beacon Landing System for Helicopters

    NASA Technical Reports Server (NTRS)

    Davis, Thomas J.; Clary, George R.; Chisholm, John P.; Macdonald, Stanley L.

    1987-01-01

    Prototype beacon landing system (BLS) allows helicopters to make precise landings in all weather. BLS easily added to existing helicopter avionic equipment and readily deployed at remote sites. Small and light, system employs X-band radar and digital processing. Variety of beams pulsed sequentially by ground station after initial interrogation by weather radar of approaching helicopter. Airborne microprocessor processes pulses to determine glide slope, course deviation, and range.

  2. MUOS: Application in Naval Helicopter Operations

    DTIC Science & Technology

    2015-03-01

    frequency HSC Helicopter Sea Combat Squadron HSL Helicopter Anti-Submarine Squadron Light HSM Helicopter Strike Maritime Squadron ISAR inverse ...using the AN/APS 147 Inverse Synthetic Aperture Radar (ISAR), which gives the aircraft the ability to identify tracks based solely on radar data. The...footprint of the satellite (see Figure 12). Each beam is like a cell tower that covers approximately 600 square miles of earth (Buck & Russ, 2007). Using a

  3. Toward Helicopter Gearbox Diagnostics from a Small Number of Examples

    NASA Astrophysics Data System (ADS)

    Zacksenhouse, M.; Braun, S.; Feldman, M.; Sidahmed, M.

    2000-07-01

    The United States Navy funded Westland Helicopters LTD to carry out a series of tests on the CH-46E helicopter transmission for the purpose of generating a database that can be used to evaluate diagnostic tools in general, and neural networks in particular. The database is extensive in the number of accelerometers, load conditions and diversity of faults. However, only 1-4 instances (levels) of each fault were included. Thus, the number of examples that can be extracted to train any classification scheme is limited, and well below the minimum required. We argue that instead the database is best used to develop specific signal generation models for the CH-46E helicopter gearbox. Such models can then be used to suggest meaningful features and derive appropriate signal-processing tools. Specifically, we demonstrate that the meshing vibrations induced by the large collector gear located on the quill shaft are significant and may interact with the vibrations induced by other elements attached to the same shaft. An appropriate model is developed and the effect, termed cross-gear-pair interaction, is studied using different signal-processing tools.

  4. Advanced Control System Increases Helicopter Safety

    NASA Technical Reports Server (NTRS)

    2008-01-01

    With support and funding from a Phase II NASA SBIR project from Ames Research Center, Hoh Aeronautics Inc. (HAI), of Lomita, California, produced HeliSAS, a low-cost, lightweight, attitude-command-attitude-hold stability augmentation system (SAS) for civil helicopters and unmanned aerial vehicles. HeliSAS proved itself in over 160 hours of flight testing and demonstrations in a Robinson R44 Raven helicopter, a commercial helicopter popular with news broadcasting and police operations. Chelton Flight Systems, of Boise, Idaho, negotiated with HAI to develop, market, and manufacture HeliSAS, now available as the Chelton HeliSAS Digital Helicopter Autopilot.

  5. Safe-life and damage-tolerant design approaches for helicopter structures

    NASA Technical Reports Server (NTRS)

    Reddick, H. K., Jr.

    1983-01-01

    The safe-life and damage-tolerant design approaches discussed apply to both metallic and fibrous composite helicopter structures. The application of these design approaches to fibrous composite structures is emphasized. Safe-life and damage-tolerant criteria are applied to all helicopter flight critical components, which are generally categorized as: dynamic components with a main and tail rotor system, which includes blades, hub and rotating controls, and drive train which includes transmission, and main and interconnecting rotor shafts; and the airframe, composed of the fuselage, aerodynamic surfaces, and landing gear.

  6. Control of helicopter rotorblade aerodynamics

    NASA Technical Reports Server (NTRS)

    Fabunmi, James A.

    1991-01-01

    The results of a feasibility study of a method for controlling the aerodynamics of helicopter rotorblades using stacks of piezoelectric ceramic plates are presented. A resonant mechanism is proposed for the amplification of the displacements produced by the stack. This motion is then converted into linear displacement for the actuation of the servoflap of the blades. A design which emulates the actuation of the servoflap on the Kaman SH-2F is used to demonstrate the fact that such a system can be designed to produce the necessary forces and velocities needed to control the aerodynamics of the rotorblades of such a helicopter. Estimates of the electrical power requirements are also presented. A Small Business Innovation Research (SBIR) Phase 2 Program is suggested, whereby a bench-top prototype of the device can be built and tested. A collaborative effort between AEDAR Corporation and Kaman Aerospace Corporation is anticipated for future effort on this project.

  7. Lytic spondylolisthesis in helicopter pilots.

    PubMed

    Froom, P; Froom, J; Van Dyk, D; Caine, Y; Ribak, J; Margaliot, S; Floman, Y

    1984-06-01

    Trauma to the back from the force of chronic stress is thought to be an etiologic factor in isthmic spondylolisthesis (SLL). The relationship of first degree spondylolisthesis to low back pain (LBP) is controversial. We compare the prevalence of SLL in helicopter pilots who are subject to strong vibrational forces, with other airforce personnel. Helicopter pilots had more than a four times higher prevalence of SLL (4.5%) than did cadets (1.0%) and transport pilots (0.9%). Low back pain was more frequent in pilots with SLL than in those without this lesion but in no case was the pain disabling or the defect progressive. We conclude that SLL may be induced by vibrational forces and although SLL is associated with LBP, the pain was little clinical significance.

  8. Experimental and analytical evaluation of efficiency of helicopter planetary stage

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    1990-01-01

    The efficiency of a helicopter transmission planetary stage was studied both experimentally and analytically. Experiments were done by using a back-to-back, test-and-slave arrangement. The experiments were a parametric study of the effects of operating conditions on efficiency. In order to enhance the analysis, a model was developed that calculates the power required for the meshing gears to displace oil trapped between the gear teeth. In general, the analysis predicted higher efficiencies than were measured. The results of this study were compared with those of other studies.

  9. Helicopter tail rotor noise analyses

    NASA Technical Reports Server (NTRS)

    George, A. R.; Chou, S. T.

    1986-01-01

    A study was made of helicopter tail rotor noise, particularly that due to interactions with the main rotor tip vortices, and with the fuselage separation mean wake. The tail rotor blade-main rotor tip vortex interaction is modelled as an airfoil of infinite span cutting through a moving vortex. The vortex and the geometry information required by the analyses are obtained through a free wake geometry analysis of the main rotor. The acoustic pressure-time histories for the tail rotor blade-vortex interactions are then calculated. These acoustic results are compared to tail rotor loading and thickness noise, and are found to be significant to the overall tail rotor noise generation. Under most helicopter operating conditions, large acoustic pressure fluctuations can be generated due to a series of skewed main rotor tip vortices passing through the tail rotor disk. The noise generation depends strongly upon the helicopter operating conditions and the location of the tail rotor relative to the main rotor.

  10. Correlate Life Predictions and Condition Indicators in Helicopter Tail Gearbox Bearings

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Bolander, Nathan; Haynes, Chris; Branning, Jeremy; Wade, Daniel R.

    2010-01-01

    Research to correlate bearing remaining useful life (RUL) predictions with Helicopter Health Usage Monitoring Systems (HUMS) condition indicators (CI) to indicate the damage state of a transmission component has been developed. Condition indicators were monitored and recorded on UH-60M (Black Hawk) tail gearbox output shaft thrust bearings, which had been removed from helicopters and installed in a bearing spall propagation test rig. Condition indicators monitoring the tail gearbox output shaft thrust bearings in UH-60M helicopters were also recorded from an on-board HUMS. The spal-lpropagation data collected in the test rig was used to generate condition indicators for bearing fault detection. A damage progression model was also developed from this data. Determining the RUL of this component in a helicopter requires the CI response to be mapped to the damage state. The data from helicopters and a test rig were analyzed to determine if bearing remaining useful life predictions could be correlated with HUMS condition indicators (CI). Results indicate data fusion analysis techniques can be used to map the CI response to the damage levels.

  11. Pneumatic boot for helicopter rotor deicing

    NASA Technical Reports Server (NTRS)

    Blaha, B. J.; Evanich, P. L.

    1981-01-01

    Pneumatic deicer boots for helicopter rotor blades were tested. The tests were conducted in the 6 by 9 ft icing research tunnel on a stationary section of a UH-IH helicopter main rotor blade. The boots were effective in removing ice and in reducing aerodynamic drag due to ice.

  12. Study of Helicopter Roll Control Effectiveness Criteria.

    DTIC Science & Technology

    1986-04-01

    variety of helicopter configurations and control system types , and a wide range of flight tasks and maneuvers. The basis of the experimental design...represent a wide range of basic helicopter rotor hub and airframe designs and flight control system types . It was intended to generally limit

  13. Neural Network Based Helicopter Low Airspeed Indicator

    DTIC Science & Technology

    1996-10-24

    This invention relates generally to virtual sensors and, more particularly, to a means and method utilizing a neural network for estimating...helicopter airspeed at speeds below about 50 knots using only fixed system parameters (i.e., parameters measured or determined in a reference frame fixed relative to the helicopter fuselage) as inputs to the neural network .

  14. 46 CFR 109.577 - Helicopter fueling.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons...

  15. 46 CFR 109.577 - Helicopter fueling.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons...

  16. 46 CFR 109.577 - Helicopter fueling.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons...

  17. 46 CFR 109.577 - Helicopter fueling.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons...

  18. 46 CFR 109.577 - Helicopter fueling.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons...

  19. Note on Hovering Turns with Tandem Helicopters

    NASA Technical Reports Server (NTRS)

    Reeder, John P; Tapscott, Robert J

    1955-01-01

    The source of an appreciable pitching-moment difference between left and right hovering turns for a tandem helicopter is described. The difference in pitching moment results from the difference in rotational speed of the counter rotating rotors with respect to the air while the helicopter is turning.

  20. Helicopter Operations and Personnel Safety (Helirescue Manual). Fourth Edition.

    ERIC Educational Resources Information Center

    Dalle-Molle, John

    The illustrated manual includes information on various aspects of helicopter rescue missions, including mission management roles for key personnel, safety rules around helicopters, requests for helicopter support, sample military air support forms, selection of landing zones, helicopter evacuations, rescuer delivery, passenger unloading, crash…

  1. The Helicopter Antenna Radiation Prediction Code (HARP)

    NASA Technical Reports Server (NTRS)

    Klevenow, F. T.; Lynch, B. G.; Newman, E. H.; Rojas, R. G.; Scheick, J. T.; Shamansky, H. T.; Sze, K. Y.

    1990-01-01

    The first nine months effort in the development of a user oriented computer code, referred to as the HARP code, for analyzing the radiation from helicopter antennas is described. The HARP code uses modern computer graphics to aid in the description and display of the helicopter geometry. At low frequencies the helicopter is modeled by polygonal plates, and the method of moments is used to compute the desired patterns. At high frequencies the helicopter is modeled by a composite ellipsoid and flat plates, and computations are made using the geometrical theory of diffraction. The HARP code will provide a user friendly interface, employing modern computer graphics, to aid the user to describe the helicopter geometry, select the method of computation, construct the desired high or low frequency model, and display the results.

  2. An evaluation of helicopter noise and vibration ride qualities criteria

    NASA Technical Reports Server (NTRS)

    Hammond, C. E.; Hollenbaugh, D. D.; Clevenson, S. A.; Leatherwood, J. D.

    1981-01-01

    Two methods of quantifying helicopter ride quality; absorbed power for vibration only and the NASA ride comfort model for both noise and vibration are discussed. Noise and vibration measurements were obtained on five operational US Army helicopters. The data were converted to both absorbed power and DISC's (discomfort units used in the NASA model) for specific helicopter flight conditions. Both models indicate considerable variation in ride quality between the five helicopters and between flight conditions within each helicopter.

  3. The impact of urban operations on helicopter noise requirements

    NASA Technical Reports Server (NTRS)

    Spector, S. R.

    1978-01-01

    The interrelationship of urban helicopter operations, helicopter noise, and the establishment of urban public-use heliports is discussed. Public resistance to urban helicopter operations due to concern for safety and noise is shown to negatively impact the establishment of public-use heliports in urban centers. It is indicated that increased government and industry effort to reduce helicopter noise is needed to ensure continued growth in the helicopter industry.

  4. Vibration Transmission through Bearings with Application to Gearboxes

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    2007-01-01

    Cabin noise has become a major concern to manufacturers and users of helicopters. Gear noise is the largest part of this unwanted sound. The crucial noise path is generally considered to be from the gears through the gear-supporting shafts and bearings into the gearbox case, and from there either through the gearbox mounts or the surrounding air to the helicopter cabin. If the noise, that is, the gear and shaft vibration, can be prevented from traveling through the gearbox bearings, then the noise cannot make its way into the helicopter cabin. Thus the vibration-transmitting properties of bearings are of paramount importance. This paper surveys the literature concerning evaluation of properties for the types of bearings used in helicopter gearboxes. A simple model is proposed to evaluate vibration transmission, using measured or calculated bearing stiffness and damping. Less-commonly used types of gearbox bearings (e.g., fluid film) are evaluated for their potential in reducing vibration transmission.

  5. Helicopter flight control compensator design

    NASA Astrophysics Data System (ADS)

    Yaici, Malika; Hariche, Kamel; Clarke, Tim

    2017-01-01

    In a precedent paper a design process is described to achieve eigenstructure assignment using block poles. Systems described in state space equations are transformed to systems in matrix fractions description (MFD) and its desired eigenstructure is transformed to a desired latent structure, which is used to construct desired block poles. In this paper, the proposed design method is applied for attitude stabilization of a Lynx helicopter in hover. An input-output feedback configuration has been chosen for more generality, and to validate the results the output responses are compared to state and output feedback control responses.

  6. Special opportunities in helicopter aerodynamics

    NASA Technical Reports Server (NTRS)

    Mccroskey, W. J.

    1983-01-01

    Aerodynamic research relating to modern helicopters includes the study of three dimensional, unsteady, nonlinear flow fields. A selective review is made of some of the phenomenon that hamper the development of satisfactory engineering prediction techniques, but which provides a rich source of research opportunities: flow separations, compressibility effects, complex vortical wakes, and aerodynamic interference between components. Several examples of work in progress are given, including dynamic stall alleviation, the development of computational methods for transonic flow, rotor-wake predictions, and blade-vortex interactions.

  7. Advanced helicopter cockpit and control configurations for helicopter combat missions

    NASA Technical Reports Server (NTRS)

    Haworth, Loran A.; Atencio, Adolph, Jr.; Bivens, Courtland; Shively, Robert; Delgado, Daniel

    1987-01-01

    Two piloted simulations were conducted by the U.S. Army Aeroflightdynamics Directorate to evaluate workload and helicopter-handling qualities requirements for single pilot operation in a combat Nap-of-the-Earth environment. The single-pilot advanced cockpit engineering simulation (SPACES) investigations were performed on the NASA Ames Vertical Motion Simulator, using the Advanced Digital Optical Control System control laws and an advanced concepts glass cockpit. The first simulation (SPACES I) compared single pilot to dual crewmember operation for the same flight tasks to determine differences between dual and single ratings, and to discover which control laws enabled adequate single-pilot helicopter operation. The SPACES II simulation concentrated on single-pilot operations and use of control laws thought to be viable candidates for single pilot operations workload. Measures detected significant differences between single-pilot task segments. Control system configurations were task dependent, demonstrating a need for inflight reconfigurable control system to match the optimal control system with the required task.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  9. Experimental Analysis of Mast Lifting and Bending Forces on Vibration Patterns Before and After Pinion Reinstallation in an OH-58 Transmission Test Rig

    NASA Technical Reports Server (NTRS)

    Huff, Edward M.; Barszcz, Eric; Turner, Irem Y.; Lewicki, David; Decker, Harry; Norvig, Peter (Technical Monitor)

    1999-01-01

    As part of a cooperative research program between NASA Ames Research Center, NASA Glenn Research Center, and the U.S. Army Laboratories, a series of experiments are being performed on the 500 HP OH-58a Transmission Test Rig at NASA Glenn Research Center. The findings reported in this paper were drawn from Phase 1 of a two-phase experiment, and are focused on the vibration response of an undamaged pinion gear and planetary system operating in situ in the transmission test rig. Phase 2 of the experiment, which is reported elsewhere, introduced a seeded fault into the pinion gear and tracked its progress in real-time. Based on methods presented here, further experimental research will be conducted to examine planetary system faults.

  10. What's Cookin' With Helicopter Microwave Landing Systems?

    NASA Technical Reports Server (NTRS)

    Taylor, Richard L.

    1980-01-01

    This article describes a joint effort of the FAA, NASA and the Helicopter Industry to establish a data base for (Microwave Landing Systems) MLS approaches, and to aid the FAA in developing the MLS Terminal Instrument Procedures (TERPS) criteria for rotary-wing IFR operations. The latter is of particular importance for it appears to signal sincere official interest in filling in the blanks in Chapter 11 of TERPS -- that portion set aside for helicopter IFR operations and recognition of the unique capabilities of the helicopter in the instrument environment. One of the program objectives is to find out what a sample of pilots can do with the MLS in a minimum machine.

  11. An improved method for design of expansion-chamber mufflers with application to an operational helicopter

    NASA Technical Reports Server (NTRS)

    Parrott, T. L.

    1973-01-01

    An improved method for the design of expansion-chamber mufflers is described and applied to the task of reducing exhaust noise generated by a helicopter. The method is an improvement of standard transmission-line theory in that it accounts for the effect of the mean exhaust-gas flow on the acoustic-transmission properties of a muffler system, including the termination boundary condition. The method has been computerized, and the computer program includes an optimization procedure that adjusts muffler component lengths to achieve a minimum specified desired transmission loss over a specified frequency range. A printout of the program is included together with a user-oriented description.

  12. Transonic Aeroelasticity Analysis For Helicopter Rotor Blade

    NASA Technical Reports Server (NTRS)

    Chang, I-Chung; Gea, Lie-Mine; Chow, Chuen-Yen

    1991-01-01

    Numerical-simulation method for aeroelasticity analysis of helicopter rotor blade combines established techniques for analysis of aerodynamics and vibrations of blade. Application of method clearly shows elasticity of blade modifies flow and, consequently, aerodynamic loads on blade.

  13. Small crack test program for helicopter materials

    NASA Technical Reports Server (NTRS)

    Annigeri, Bal; Schneider, George

    1994-01-01

    Crack propagation tests were conducted to determine crack growth behavior in five helicopter materials for surface cracks between 0.005 to 0.020 inches in depth. Constant amplitude tests were conducted at stress ratios R equals 0.1 and 0.5, and emphasis was placed on near threshold data (i.e., 10-8 to 10-6 inches/cycle). Spectrum tests were conducted using a helicopter spectrum. The test specimen was an unnotched tension specimen, and cracks were initiated from a small EDM notch. An optical/video system was used to monitor crack growth. The material for the test specimens was obtained from helicopter part forgings. Testing was conducted at stresses below yield to reflect actual stresses in helicopter parts.

  14. 14 CFR 93.103 - Helicopter operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Orient Point, shall utilize the North Shore Helicopter route and altitude, as published. (b) Pilots may deviate from the route and altitude requirements of paragraph (a) of this section when necessary...

  15. 14 CFR 93.103 - Helicopter operations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Orient Point, shall utilize the North Shore Helicopter route and altitude, as published. (b) Pilots may deviate from the route and altitude requirements of paragraph (a) of this section when necessary...

  16. Civil helicopter design and operational requirement

    NASA Technical Reports Server (NTRS)

    Waters, K. T.

    1978-01-01

    Design and operational requirements and other factors that have a restraining influence on expansion of the helicopter market are discussed. The needs of operators, users, pilots and the community at large are examined. The impact of future technology developments and other trends such as use, energy shortages, and civil and military helicopter requirements and development is assessed. Areas where research and development are needed to provide opportunities for lowering life cycle costs and removing barriers to further expansion of the industry are analyzed.

  17. Helicopter training simulators: Key market factors

    NASA Technical Reports Server (NTRS)

    Mcintosh, John

    1992-01-01

    Simulators will gain an increasingly important role in training helicopter pilots only if the simulators are of sufficient fidelity to provide positive transfer of skills to the aircraft. This must be done within an economic model of return on investment. Although rotor pilot demand is still only a small percentage of overall pilot requirements, it will grow in significance. This presentation described the salient factors influencing the use of helicopter training simulators.

  18. The effective acoustic environment of helicopter crewmen

    NASA Technical Reports Server (NTRS)

    Camp, R. T., Jr.; Mozo, B. T.

    1978-01-01

    Methods of measuring the composite acoustic environment of helicopters in order to quantify the effective acoustic environment of the crewmen and to assess the real acoustic hazards of the personnel are examined. It is indicated that the attenuation characteristics of the helmets and hearing protectors and the variables of the physiology of the human ear be accounted for in determining the effective acoustic environment of Army helicopter crewmen as well as the acoustic hazards of voice communications systems noise.

  19. Tail Rotor Airfoils Stabilize Helicopters, Reduce Noise

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Founded by former Ames Research Center engineer Jim Van Horn, Van Horn Aviation of Tempe, Arizona, built upon a Langley Research Center airfoil design to create a high performance aftermarket tail rotor for the popular Bell 206 helicopter. The highly durable rotor has a lifetime twice that of the original equipment manufacturer blade, reduces noise by 40 percent, and displays enhanced performance at high altitudes. These improvements benefit helicopter performance for law enforcement, military training, wildfire and pipeline patrols, and emergency medical services.

  20. The Evolution of the Advanced Attack Helicopter

    DTIC Science & Technology

    1975-06-06

    engineering laboratory at McCook Field, Dayton, Ohio. The first helicopter which appears to have been evaluated was th. Peter Cooper Hewitt design...through five decades to an evaluation of the Peter Cooper Hewitt design in 1918. The first helicopter contracted for by the military was the 199 200 de...used counter-rotating rotors, control vanes below, 24-hp Antoinette engine, two 20 foot rotors. On 13 Nov lifted inventor and two passen- gers, a

  1. Helicopter Performance Evaluation (HELPE) Computer Model

    DTIC Science & Technology

    1994-07-01

    questions : * For a given helicopter at given flight conditions and specified mission weight, how fast can the helicopter cruise in level flight...possible level speed its maneuverability in a turn, and its hover and climb capabilities in the in-ground and out-of-ground effects modes. The code... levels , and mappings ..... 2 2. Available engine power output as a function of altitude "h".................... 8 3. Schematic drawing of the thrust

  2. 77 FR 23388 - Airworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-19

    ... helicopters with certain main rotor blades installed to reduce the life limit of those blades. This AD is... rotor blade failed because of fatigue cracking. These actions are intended to prevent failure of the main rotor blade and subsequent loss of control of the helicopter. DATES: This AD becomes effective...

  3. 78 FR 56148 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-12

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... service information identified in this AD, contact Bell Helicopter Textron Canada Limited, 12,800 Rue de l...-2009-32, dated July 24, 2009, issued by Transport Canada Civil Aviation (TCCA), which is the...

  4. 78 FR 54751 - Airworthiness Directives; Bell Helicopter Textron Canada Inc. Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-06

    ...-17576; AD 2013-18-03] RIN 2120-AA64 Airworthiness Directives; Bell Helicopter Textron Canada Inc... new airworthiness directive (AD) for certain Bell Helicopter Textron Canada Inc. (BHT) Model 206A... Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4; telephone (450) 437-2862 or...

  5. Analysis of helicopter noise data using international helicopter noise certification procedures

    NASA Astrophysics Data System (ADS)

    Newman, J. S.; Rickley, E. J.; Levanduski, D. A.; Woolridge, S. B.

    1986-03-01

    The results of a Federal Aviation Administration (FAA) noise measurement flight test program involving seven helicopters are documented. Noise levels were established using the basic testing, reduction and analysis techniques specified by the International Civil Aviation Organization (ICAO) for helicopter noise certification, supplemented with some procedural refinements contained in ICAO Working Group II recommendations for incorporation into the standard.

  6. Instrument Approach Aids for Helicopters.

    DTIC Science & Technology

    1982-07-01

    Me 3.9 "HELICOPTER ONLY" CRITERIA 3-27 h3-30 3.9.1 Procedure Limitations 3-30 3.9.2 Point in Space Concept 3-30 3.9.3 Descent Gradients 3-30 3.9.4...601-800 ft 3/4 mile 801 ft and up 1 mile * Point in space procedures HAS Visibility Minimum 250-800 ft 3/4 mile 801 ft and up 1 mile 1.3 ESTABLISHED...procedures. In the analysis of visibility data most procedures were able to achieve 1/2 mile minimums. A few, primarily the RNAV Point in Space

  7. Long-gauge FBGs interrogated by DTR3 for dynamic distributed strain measurement of helicopter blade model

    NASA Astrophysics Data System (ADS)

    Nishiyama, M.; Igawa, H.; Kasai, T.; Watanabe, N.

    2014-05-01

    In this paper, we describe characteristics of distributed strain sensing based on a Delayed Transmission/Reflection Ratiometric Reflectometry (DTR3) scheme with a long-gauge Fiber Bragg Grating (FBG), which is attractive to dynamic structural deformation monitoring such as a helicopter blade and an airplane wing. The DTR3 interrogator using the longgauge FBG has capability of detecting distributed strain with 50 cm spatial resolution in 100 Hz sampling rate. We evaluated distributed strain sensing characteristics of the long-gauge FBG attached on a 5.5 m helicopter blade model in static tests and free vibration dynamic tests.

  8. Advanced Rotorcraft Transmission (ART) program

    NASA Technical Reports Server (NTRS)

    Heath, Gregory F.; Bossler, Robert B., Jr.

    1993-01-01

    Work performed by the McDonnell Douglas Helicopter Company and Lucas Western, Inc. within the U.S. Army/NASA Advanced Rotorcraft Transmission (ART) Program is summarized. The design of a 5000 horsepower transmission for a next generation advanced attack helicopter is described. Government goals for the program were to define technology and detail design the ART to meet, as a minimum, a weight reduction of 25 percent, an internal noise reduction of 10 dB plus a mean-time-between-removal (MTBR) of 5000 hours compared to a state-of-the-art baseline transmission. The split-torque transmission developed using face gears achieved a 40 percent weight reduction, a 9.6 dB noise reduction and a 5270 hour MTBR in meeting or exceeding the above goals. Aircraft mission performance and cost improvements resulting from installation of the ART would include a 17 to 22 percent improvement in loss-exchange ratio during combat, a 22 percent improvement in mean-time-between-failure, a transmission acquisition cost savings of 23 percent of $165K, per unit, and an average transmission direct operating cost savings of 33 percent, or $24K per flight hour. Face gear tests performed successfully at NASA Lewis are summarized. Also, program results of advanced material tooth scoring tests, single tooth bending tests, Charpy impact energy tests, compact tension fracture toughness tests and tensile strength tests are summarized.

  9. Requirements for a Hydrogen Powered All-Electric Manned Helicopter

    NASA Technical Reports Server (NTRS)

    Datta, Anubhav

    2012-01-01

    The objective of this paper is to set propulsion system targets for an all-electric manned helicopter of ultra-light utility class to achieve performance comparable to combustion engines. The approach is to begin with a current two-seat helicopter (Robinson R 22 Beta II-like), design an all-electric power plant as replacement for its existing piston engine, and study performance of the new all-electric aircraft. The new power plant consists of high-pressure Proton Exchange Membrane fuel cells, hydrogen stored in 700 bar type-4 tanks, lithium-ion batteries, and an AC synchronous permanent magnet motor. The aircraft and the transmission are assumed to remain the same. The paper surveys the state of the art in each of these areas, synthesizes a power plant using best available technologies in each, examines the performance achievable by such a power plant, identifies key barriers, and sets future technology targets to achieve performance at par with current internal combustion engines.

  10. 77 FR 58973 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-25

    ... ] power supply disruptions while a helicopter is on the ground, causing the landing gear to retract and... power supply disruptions, which caused the landing gear to retract and the helicopter to drop,...

  11. 77 FR 18969 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-29

    ... Directives; Sikorsky Aircraft Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... (AD) for certain Sikorsky Aircraft Corporation (Sikorsky) Model S-76C helicopters. This proposed AD is... Aircraft Corporation, Attn: Manager, Commercial Technical Support, mailstop s581a, 6900 Main...

  12. 77 FR 57524 - Stage 3 Helicopter Noise Certification Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-18

    ... applications for a new helicopter type design and for a supplemental type certificate for those new type designs. A helicopter type certificated under this standard would be designated as a Stage 3 helicopter... standards of the International Civil Aviation Organization (ICAO). The proposal of these more...

  13. 14 CFR 135.207 - VFR: Helicopter surface reference requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false VFR: Helicopter surface reference... VFR/IFR Operating Limitations and Weather Requirements § 135.207 VFR: Helicopter surface reference requirements. No person may operate a helicopter under VFR unless that person has visual surface reference...

  14. 78 FR 17593 - Airworthiness Directives; Bell Helicopter Textron, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... helicopters. This AD requires establishing a lower life limit on certain swashplate outer ring assemblies... lead to the loss of main rotor (M/R) blade pitch control and subsequent loss of helicopter control..., which could lead to the loss of M/R blade pitch control and subsequent loss of helicopter...

  15. Advanced transmission studies

    NASA Technical Reports Server (NTRS)

    Coy, John J.; Bill, Robert C.

    1988-01-01

    The NASA Lewis Research Center and the U.S. Army Aviation Systems Command share an interest in advancing the technology for helicopter propulsion systems. In particular, this paper presents highlights from that portion of the program in drive train technology and the related mechanical components. The major goals of the program are to increase the life, reliability, and maintainability; reduce the weight, noise, and vibration; and maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for future transmission research is presented.

  16. Degenerative Changes of Spine in Helicopter Pilots

    PubMed Central

    Byeon, Joo Hyeon; Kim, Jung Won; Jeong, Ho Joong; Sim, Young Joo; Kim, Dong Kyu; Choi, Jong Kyoung; Im, Hyoung June

    2013-01-01

    Objective To determine the relationship between whole body vibration (WBV) induced helicopter flights and degenerative changes of the cervical and lumbar spine. Methods We examined 186 helicopter pilots who were exposed to WBV and 94 military clerical workers at a military hospital. Questionnaires and interviews were completed for 164 of the 186 pilots (response rate, 88.2%) and 88 of the 94 clerical workers (response rate, 93.6%). Radiographic examinations of the cervical and the lumbar spines were performed after obtaining informed consent in both groups. Degenerative changes of the cervical and lumbar spines were determined using four radiographs per subject, and diagnosed by two independent, blinded radiologists. Results There was no significant difference in general and work-related characteristics except for flight hours and frequency between helicopter pilots and clerical workers. Degenerative changes in the cervical spine were significantly more prevalent in the helicopter pilots compared with control group. In the cervical spine multivariate model, accumulated flight hours (per 100 hours) was associated with degenerative changes. And in the lumbar spine multivariate model, accumulated flight hours (per 100 hours) and age were associated with degenerative changes. Conclusion Accumulated flight hours were associated with degenerative changes of the cervical and lumbar spines in helicopter pilots. PMID:24236259

  17. Evolution of civil aeromedical helicopter aviation.

    PubMed

    Meier, D R; Samper, E R

    1989-07-01

    The rapid increase in the use of helicopters for hospital transport during the 1980s is the culmination of several hundred years of military medical innovation. Mass battefield casualties spurred both technologic and medical changes necessary for today's sophisticated helicopter systems in use worldwide, particularly in the United States. The Napoleonic Era and the American Civil War provided the framework for the evolution of today's state-of-the-art emergency medical techniques. The use of airplanes to evacuate the wounded eventually led to using helicopters for rescue missions in World War II. The combat experiences of the United States in Korea, the British in Malaya, and the French in Indochina proved that rotary-wing aircraft were invaluable in reducing battlefield death rates. Any skepticism about the efficacy of helicopter medical evacuation was erased during the Vietnam conflict. As an integral part of the modern battlefield, these specialized aircraft became a necessity. The observations and experience of American servicemen and medical personnel in Vietnam established the foundation for the acceptance of helicopter transport in modern hospital systems.

  18. All-weather capability for rescue helicopters

    NASA Astrophysics Data System (ADS)

    Kreitmair-Steck, Wolfgang; Haisch, Stefan

    2001-08-01

    In Germany as well as in numerous other countries the air rescue system has been extended significantly since the first operation of the rescue helicopter Christoph 1. The primary target of the air rescue system was to guarantee fast and efficient emergency medical services for victims of accidents. During the years, the scope of the helicopter operations has been extended not only to other types of emergency medical services, but also to secondary medical services like the displacement of patients from hospitals to special service hospitals. While in general the displacement of patients is operated from well known and registered helipads, the primary rescue service currently has to rely on available onboard systems only. Those operations are risky and challenging for the pilots because of time pressure and the danger of obstacles in the environment of the helicopter. In addition, reduced visibility due to fog, rainfall or low light levels can further increase the risks or can make the services unavailable at all. Almost one decade ago, Eurocopter started the investigation of technologies and systems that could help the pilots to perform their tasks with reduced workload and risk, and to allow for a 24 h operation of helicopters irrespective of the weather conditions. After a number of preliminary studies, in 1995 the research program 'All-weather helicopter' has been started as a joint effort of Eurocopter and the supplier industry in Europe. The first phase of the program has been successfully completed in 1999 and the second phase is currently in progress.

  19. Helicopter stability during aggressive maneuvers

    NASA Astrophysics Data System (ADS)

    Mohan, Ranjith

    The dissertation investigates helicopter trim and stability during level bank-angle and diving bank-angle turns. The level turn is moderate in that sufficient power is available to maintain level maneuver, and the diving turn is severe where the power deficit is overcome by the kinetic energy of descent. The investigation basically represents design conditions where the peak loading goes well beyond the steady thrust limit and the rotor experiences appreciable stall. The major objectives are: (1) to assess the sensitivity of the trim and stability predictions to the approximations in modeling stall, (2) to correlate the trim predictions with the UH-60A flight test data, and (3) to demonstrate the feasibility of routinely using the exact fast-Floquet periodic eigenvector method for mode identification in the stability analysis. The UH-60A modeling and analysis are performed using the comprehensive code RCAS (Army's Rotorcraft Comprehensive Analysis System). The trim and damping predictions are based on quasisteady stall, ONERA-Edlin (Equations Differentielles Lineaires) and Leishman-Beddoes dynamic stall models. From the correlation with the test data, the strengths and weaknesses of the trim predictions are presented.

  20. Helicopter emergency medical service in mountainous areas.

    PubMed

    Tomazin, Iztok

    2009-01-01

    The outcome of patient care can be dramatically improved by bringing rapid rescue-medical treatment to the scene and by rapid transport to a medical facility. In mountainous areas this is usually possible only with the use of helicopters. ICAR MEDCOM suggests international standards for competent and safe response to medical problems in mountainous and wilderness areas. Rescue helicopters should work within the existing emergency medical system with appropriate mountain rescue and medically-trained personnel and with medical and rescue equipment on board. Safety is most important issue in mountain rescue. Activation and approach time should be as short as possible. All persons responsible for activation and realization of a helicopter rescue operation should be aware of all specific problems in the mountains and wilderness.

  1. Flight service evaluation of composite helicopter components

    NASA Technical Reports Server (NTRS)

    Mardoian, G. H.; Ezzo, M. B.

    1986-01-01

    This report presents an assessment of composite helicopter tail rotor spars and horizontal stabilizers, exposed to the effects of the environment, after up to five and a half years of commercial service. This evaluation is supported by test results of helicopter components and panels which have been exposed to outdoor environmental effects since September 1979. Full scale static and fatigue tests have been conducted on graphite/epoxy and Kevlar/epoxy composite components obtained from Sikorsky Model S-76 helicopters in commercial operations in the Gulf Coast region of Louisiana. Small scale static and fatigue tests are being conducted on coupons obtained from panels under exposure to outdoor conditions in Stratford, Connecticut and West Palm, Florida. The panel layups are representative of the S-76 components. Additionally, this report discusses the results of moisture absorption evaluations and strength tests on the S-76 components and composite panels with up to five years of outdoor exposure.

  2. Flight service evaluation of composite helicopter components

    NASA Technical Reports Server (NTRS)

    Rich, M. J.; Lowry, D. W.

    1985-01-01

    An assessment of composite helicopter structures, exposed to environmental effects, after four years of commercial service is presented. This assessment is supported by test results of helicopter components and test panels which have been exposed to environmental effects since late 1979. Full scale static and fatigue tests are being conducted on composite components obtained from S-76 helicopters in commercial operations in the Gulf Coast region of Louisiana. Small scale tests are being conducted on coupons obtained from panels being exposed to outdoor conditions in Stratford, Connecticut and West Palm Beach, Florida. The panel layups represent S-76 components. Moisture evaluations and strength tests are being conducted, on the S-76 components and panels, over a period of eight years. Results are discussed for components and panels with up to four years of exposure.

  3. Minimum-complexity helicopter simulation math model

    NASA Technical Reports Server (NTRS)

    Heffley, Robert K.; Mnich, Marc A.

    1988-01-01

    An example of a minimal complexity simulation helicopter math model is presented. Motivating factors are the computational delays, cost, and inflexibility of the very sophisticated math models now in common use. A helicopter model form is given which addresses each of these factors and provides better engineering understanding of the specific handling qualities features which are apparent to the simulator pilot. The technical approach begins with specification of features which are to be modeled, followed by a build up of individual vehicle components and definition of equations. Model matching and estimation procedures are given which enable the modeling of specific helicopters from basic data sources such as flight manuals. Checkout procedures are given which provide for total model validation. A number of possible model extensions and refinement are discussed. Math model computer programs are defined and listed.

  4. Neuro-optimal control of helicopter UAVs

    NASA Astrophysics Data System (ADS)

    Nodland, David; Ghosh, Arpita; Zargarzadeh, H.; Jagannathan, S.

    2011-05-01

    Helicopter UAVs can be extensively used for military missions as well as in civil operations, ranging from multirole combat support and search and rescue, to border surveillance and forest fire monitoring. Helicopter UAVs are underactuated nonlinear mechanical systems with correspondingly challenging controller designs. This paper presents an optimal controller design for the regulation and vertical tracking of an underactuated helicopter using an adaptive critic neural network framework. The online approximator-based controller learns the infinite-horizon continuous-time Hamilton-Jacobi-Bellman (HJB) equation and then calculates the corresponding optimal control input that minimizes the HJB equation forward-in-time. In the proposed technique, optimal regulation and vertical tracking is accomplished by a single neural network (NN) with a second NN necessary for the virtual controller. Both of the NNs are tuned online using novel weight update laws. Simulation results are included to demonstrate the effectiveness of the proposed control design in hovering applications.

  5. Disorientation phenomena in naval helicopter pilots.

    PubMed

    Tormes, F R; Guedry, F E

    1975-04-01

    The incidence of pilot disorientation in fixed- and rotary-wing aircraft has been previously investigated, but special orientation problems of naval helicopter pilots engaged in operations at sea and landing on moving platforms have not been previously investigated. A questionnaire concerning disorientations was answered anonymously and individually by 104 active naval helicopter pilots. Fifty-six percent indicated one or more espisodes of severe disorientation, and 8.6% indicated having experienced severe disorientation five or more times while piloting helicopters. A number of factors conducive to disorientation were identified. Some precipitating factors appear to be specific to operations over water or over a moving deck, although some of these may well have their counterparts in special operations over land. Other factors are common to fixed-wing as well as rotary-wing aircraft. A number of potential countermeasures for various precipitating factors are discussed.

  6. Workload and operational fatigue in helicopter pilots.

    PubMed

    Rotondo, G

    1978-02-01

    In light of the modern aetiopathogenic views, a brief review was made concerning possible causes of operational fatigue to which flying personnel in general are exposed in the exercise of flying activity. The author then describes and analyzes the meaning and importance of the various stressing factors that constitute the physical and psychic workload to which the helicopter pilot is subjected in performing his professional activities. Also analyzed are the influences exercised, both separately and jointly, on the genesis of flight fatigue in helicopter pilots by stressing and fatiguing effects of vibrations, noise, and psycho-emotional and psycho-sensorial factors related to the variety and danger of utilization of this modern aircraft. Such an analytical investigation enables the author to conclude that one must admit that helicopter piloting involves a psycho-physical workload certainly no less than that required by more powerful and faster aircraft.

  7. Helicopter impulsive noise: Theoretical and experimental status

    NASA Technical Reports Server (NTRS)

    Schmitz, F. H.; Yu, Y. H.

    1983-01-01

    The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanism is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanism of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.

  8. Validation of helicopter noise prediction techniques

    NASA Technical Reports Server (NTRS)

    Succi, G. P.

    1981-01-01

    The current techniques of helicopter rotor noise prediction attempt to describe the details of the noise field precisely and remove the empiricisms and restrictions inherent in previous methods. These techniques require detailed inputs of the rotor geometry, operating conditions, and blade surface pressure distribution. The purpose of this paper is to review those techniques in general and the Farassat/Nystrom analysis in particular. The predictions of the Farassat/Nystrom noise computer program, using both measured and calculated blade surface pressure data, are compared to measured noise level data. This study is based on a contract from NASA to Bolt Beranek and Newman Inc. with measured data from the AH-1G Helicopter Operational Loads Survey flight test program supplied by Bell Helicopter Textron.

  9. A comprehensive plan for helicopter drag reduction

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Montana, P. S.

    1975-01-01

    Current helicopters have parasite drag levels 6 to 10 times as great as fixed wing aircraft. The commensurate poor cruise efficiency results in a substantial degradation of potential mission capability. The paper traces the origins of helicopter drag and shows that the problem (primarily due to bluff body flow separation) can be solved by the adoption of a comprehensive research and development plan. This plan, known as the Fuselage Design Methodology, comprises both nonaerodynamic and aerodynamic aspects. The aerodynamics are discussed in detail and experimental and analytical programs are described which will lead to a solution of the bluff body problem. Some recent results of work conducted at the Naval Ship Research and Development Center (NSRDC) are presented to illustrate these programs. It is concluded that a 75-per cent reduction of helicopter drag is possible by the full implementation of the Fuselage Design Methodology.

  10. A critical care helicopter system in trauma.

    PubMed Central

    Jacobs, L. M.; Bennett, B.

    1989-01-01

    Civilian helicopters and emergency medical services in the United States have been in existence for approximately 15 years. The rapid growth of this type of health care delivery coupled with an increasing number of accidents has prompted professional and lay scrutiny of these programs. Although they have a demonstrated history of benefit to patients, the type and severity of injuries to patients who are eligible for helicopter transportation need further definition. The composition of the medical crews and the benefits that particular crew members bring to the patients require ongoing evaluation. Significant questions regarding the number of pilots in a helicopter and in a program remain to be answered. This article reviews the role of emergency medical air transport services in providing care to trauma patients, staff training and evaluation, and safety criteria and offers recommendations to minimize risks to patients and crews. PMID:2695653

  11. Validation of helicopter noise prediction techniques

    NASA Astrophysics Data System (ADS)

    Succi, G. P.

    1981-04-01

    The current techniques of helicopter rotor noise prediction attempt to describe the details of the noise field precisely and remove the empiricisms and restrictions inherent in previous methods. These techniques require detailed inputs of the rotor geometry, operating conditions, and blade surface pressure distribution. The purpose of this paper is to review those techniques in general and the Farassat/Nystrom analysis in particular. The predictions of the Farassat/Nystrom noise computer program, using both measured and calculated blade surface pressure data, are compared to measured noise level data. This study is based on a contract from NASA to Bolt Beranek and Newman Inc. with measured data from the AH-1G Helicopter Operational Loads Survey flight test program supplied by Bell Helicopter Textron.

  12. ALLFlight: multisensor data fusion for helicopter operations

    NASA Astrophysics Data System (ADS)

    Doehler, H.-U.; Lueken, T.

    2010-04-01

    The objective of the project ALLFlight (Assisted Low Level Flight and Landing on Unprepared Landing Sites) is to demonstrate and evaluate the characteristics of different sensors for helicopter operations within degraded visual environments, such as brownout or whiteout. The sensor suite, which is mounted onto DLR's research helicopter EC135 consists of standard color or black and white TV cameras, an un-cooled thermal infrared camera (EVS-1000, Max-Viz, USA), an optical radar scanner (HELLAS-W, EADS, Germany; a millimeter wave radar system (AI-130, ICx Radar Systems, Canada). Data processing is designed and realized by a sophisticated, high performance sensor co-computer (SCC) cluster architecture, which is installed into the helicopter's experimental electronic cargo bay. This paper describes applied methods and the software architecture in terms of real time data acquisition, recording, time stamping and sensor data fusion. First concepts for a pilot HMI are presented as well.

  13. Helicopter Mechanic Career Ladder (AFSC 431X0C/D).

    DTIC Science & Technology

    1986-05-01

    SYSTEMS ON H-i HELICOPTERS 88 G352 LAUNCH H-i HELICOPTERS 88 G415 REMOVE OR INSTALL BATTERIES ON H-i HELICOPTERS 88 G351 JACK H-i HELICOPTERS 88 F165...PREPARE AFTO FORMS 781H (AEROSPACE VEHICLE FLIGHT STATUS AND MAINTENANCE DOCUMENT) 72 G351 JACK H-i HELICOPTERS 72 E122 PREPARE AFTO FORMS 350...H-I HELICOPTERS 97 G308 ATTACH OR DETACH TOW BARS ON H-i HELICOPTERS 96 G351 JACK H-I HELICOPTERS 95 G507 TIE DOWN BLADES ON H-i HELICOPTERS 93 G336

  14. Helicopter trajectory planning using optimal control theory

    NASA Technical Reports Server (NTRS)

    Menon, P. K. A.; Cheng, V. H. L.; Kim, E.

    1988-01-01

    A methodology for optimal trajectory planning, useful in the nap-of-the-earth guidance of helicopters, is presented. This approach uses an adjoint-control transformation along with a one-dimensional search scheme for generating the optimal trajectories. In addition to being useful for helicopter nap-of-the-earth guidance, the trajectory planning solution is of interest in several other contexts, such as robotic vehicle guidance and terrain-following guidance for cruise missiles and aircraft. A distinguishing feature of the present research is that the terrain constraint and the threat envelopes are incorporated in the equations of motion. Second-order necessary conditions are examined.

  15. CMU's autonomous helicopter explores new territory.

    NASA Astrophysics Data System (ADS)

    Charles, J.

    1998-10-01

    In the summer of 1998, several members of Carnegie Mellon University's (CMUs) Autonomous Helicopter Project team joined NASA on a multidisciplinary expedition to the Canadian Arctic's Haughton Crater. NASA was willing to travel to such a remote corner of the globe because of its similarity to an even more remote locale - Mars. Researchers are studying the 23-million-year-old meteorite impact crater in the hope of learning more about Mars's environment. While there, they also tested a number of technologies that will enable future exploration of Mars, including CMU's autonomous helicopter.

  16. Influence of maneuverability on helicopter combat effectiveness

    NASA Technical Reports Server (NTRS)

    Falco, M.; Smith, R.

    1982-01-01

    A computational procedure employing a stochastic learning method in conjunction with dynamic simulation of helicopter flight and weapon system operation was used to derive helicopter maneuvering strategies. The derived strategies maximize either survival or kill probability and are in the form of a feedback control based upon threat visual or warning system cues. Maneuverability parameters implicit in the strategy development include maximum longitudinal acceleration and deceleration, maximum sustained and transient load factor turn rate at forward speed, and maximum pedal turn rate and lateral acceleration at hover. Results are presented in terms of probability of skill for all combat initial conditions for two threat categories.

  17. Efficient fault diagnosis of helicopter gearboxes

    NASA Technical Reports Server (NTRS)

    Chin, H.; Danai, K.; Lewicki, D. G.

    1993-01-01

    Application of a diagnostic system to a helicopter gearbox is presented. The diagnostic system is a nonparametric pattern classifier that uses a multi-valued influence matrix (MVIM) as its diagnostic model and benefits from a fast learning algorithm that enables it to estimate its diagnostic model from a small number of measurement-fault data. To test this diagnostic system, vibration measurements were collected from a helicopter gearbox test stand during accelerated fatigue tests and at various fault instances. The diagnostic results indicate that the MVIM system can accurately detect and diagnose various gearbox faults so long as they are included in training.

  18. Contingency power concepts for helicopter turboshaft engine

    NASA Technical Reports Server (NTRS)

    Hirschkron, R.; Davis, R. H.; Goldstein, D. N.; Haynes, J. F.; Gauntner, J. W.

    1984-01-01

    Twin helicopter engines are often sized by power requirement of safe mission completion after the failure of one of the two engines. This study was undertaken for NASA Lewis by General Electric Co. to evaluate the merits of special design features to provide a 2-1/2 minute Contingency Power rating, permitting an engine size reduction. The merits of water injection, cooling flow modulation, throttle push and an auxiliary power plant were evaluated using military life cycle cost (LCC) and commercial helicopter direct operating cost (DOC) merit factors in a rubber engine/rubber aircraft scenario.

  19. A vibration monitoring acquisition and diagnostic system for helicopter drive train bench tests

    NASA Astrophysics Data System (ADS)

    Dousis, Dimitri A.

    An automated drive train test stand vibration monitoring system called VMADS has been developed by Bell Helicopter Textron, Inc., and has been installed at Bell's transmission bench test facility. VMADS provides the operator with warning and alarm indications for preselected degraded conditions, and acquires vibration data to be used by engineers to improve the diagnostics for better fault detection and fault isolation. VMADS is used as a test bed for new monitoring and diagnostic algorithm evaluation and validation, a necessary step to ensure development of accurate, reliable integrated health usage monitoring systems for the Bell rotorcraft fleet. This paper highlights the VMADS features for helicopter and tiltrotor aircraft drive train bench test monitoring and diagnostics and discusses supportive ongoing health and usage monitoring activities at BHTI, both military and commercial for enhanced safety and reduced maintenance costs. Bell is translating VMADS developed capability to airborne applications, while simultaneously enhancing the original VMADS capabilities.

  20. Helicopter Parents Can Be a Good Thing

    ERIC Educational Resources Information Center

    Hiltz, Julie

    2015-01-01

    Helicopter parents get a bad rap. Teachers and administrators should view them as a resource--not a nuisance. By encouraging open communication, teachers can begin to understand the motivations of these parents and find creative ways to connect them with opportunities to promote their students' academic success and the school's overall…

  1. 29 CFR 1910.183 - Helicopters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... cargo hooks shall have the electrical activating device so designed and installed as to prevent... employee shall be permitted to approach within 50 feet of the helicopter when the rotor blades are turning... blades rotating, all employees shall remain in full view of the pilot and keep in a crouched position....

  2. 29 CFR 1910.183 - Helicopters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... cargo hooks shall have the electrical activating device so designed and installed as to prevent... employee shall be permitted to approach within 50 feet of the helicopter when the rotor blades are turning... blades rotating, all employees shall remain in full view of the pilot and keep in a crouched position....

  3. 29 CFR 1910.183 - Helicopters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... cargo hooks shall have the electrical activating device so designed and installed as to prevent... employee shall be permitted to approach within 50 feet of the helicopter when the rotor blades are turning... blades rotating, all employees shall remain in full view of the pilot and keep in a crouched position....

  4. Flight service evaluation of composite helicopter components

    NASA Technical Reports Server (NTRS)

    Mardoian, George H.; Ezzo, Maureen B.

    1990-01-01

    An assessment is presented of ten composite tail rotor spars and four horizontal stabilizers exposed to the effects of in-flight commercial service for up to nine years to establish realistic environmental factors for use in future designs. This evaluation is supported by test results of helicopter components and panels which have been exposed to outdoor environmental effects since 1979. Full scale static and fatigue tests were conducted on graphite/epoxy and Kevlar/epoxy composite components removed from Sikorsky Model S-76 helicopters in commercial operations off the Gulf Coast of Louisiana. Small scale static and fatigue tests were conducted on coupons obtained from panels exposed to outdoor conditions in Stratford, CT and West Palm Beach, Florida. The panel materials and ply configurations were representative of the S-76 components. The results are discussed of moisture analyses and strength tests on both the S-76 components and composite panels after up to nine years of outdoor exposure. Full scale tests performed on the helicopter components did not disclose any significant reductions from the baseline strengths. The results increased confidence in the long term durability of advanced composite materials in helicopter structural applications.

  5. Finite element analysis of helicopter structures

    NASA Technical Reports Server (NTRS)

    Rich, M. J.

    1978-01-01

    Application of the finite element analysis is now being expanded to three dimensional analysis of mechanical components. Examples are presented for airframe, mechanical components, and composite structure calculations. Data are detailed on the increase of model size, computer usage, and the effect on reducing stress analysis costs. Future applications for use of finite element analysis for helicopter structures are projected.

  6. Helicopter support of North Sea oil exploration.

    PubMed

    Preston, F S

    1978-04-01

    Exploration for oil beneath the North Sea started in the early 1960's with the discovery of natural gas and oil in the southern part between the coasts of East Anglia and the Netherlands. Since then oil exploration has built up considerably, the main effort moving northwards between the Shetland Islands and the Norwegian coasts. The helicopter offered the most direct and rapid contact with off-shore oil rigs and since these early days and immense helicopter operation has been built up round the borders of the North Sea by all the nations involved. Flying conditions in this area, particularly in winter, are at times difficult if not to say hazardous. Nevertheless, a sophisticated helicopter support service has been built up using modern aircraft and equipment which is unique in aviation history. This paper attempts to trace the history of the service, the operational problems involved and the special needs such as survival equipment and clothing. In addition, a co-ordinated air/sea rescue service largely based on helicopters has been built up and provides not only rescue facilities for possible rig disasters but also for shipping emergencies in the area.

  7. HH-60D night hawk helicopter

    NASA Technical Reports Server (NTRS)

    Richardson, C. S.

    1984-01-01

    Fundamental development issues, system requirements and improvements are reported for the HH-60D night hawk helicopter. The HH-60D mission requirements are for combat search and rescue (aerospace rescue and recovery service user based at Scott AFB) and special operations (special operations forces based at Hurlburt AFB). Cockpit design, computer architecture and software are described in detail.

  8. Computer Programs for Helicopter Aerodynamic Stability Evaluation

    DTIC Science & Technology

    1976-08-01

    augmentation system . Two methods of calculating the required stability derivatives and solution of the equations of motion in terms of period and time to damp or time histories for various control motions are shown....The three equations of motion for helicopters are reviewed for both pitch and roll. These include provisions for a simplified second order stability

  9. 29 CFR 1910.183 - Helicopters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the system with the employees in advance of hoisting the load. This applies to both radio and hand... employee shall be permitted to approach within 50 feet of the helicopter when the rotor blades are turning... blades rotating, all employees shall remain in full view of the pilot and keep in a crouched position....

  10. Technical Workshop: Advanced Helicopter Cockpit Design

    NASA Technical Reports Server (NTRS)

    Hemingway, J. C. (Editor); Callas, G. P. (Editor)

    1984-01-01

    Information processing demands on both civilian and military aircrews have increased enormously as rotorcraft have come to be used for adverse weather, day/night, and remote area missions. Applied psychology, engineering, or operational research for future helicopter cockpit design criteria were identified. Three areas were addressed: (1) operational requirements, (2) advanced avionics, and (3) man-system integration.

  11. Computerized Analysis Of Helicopter-Rotor Aeroelasticity

    NASA Technical Reports Server (NTRS)

    Reddy, T. S. R.

    1988-01-01

    Analysis of aeroelastic stability of helicopter rotor automated. Symbolic-manipulation program, HESL, written in FORTRAN, used to aid in derivation of government equations of motion for elastic-bladed rotor. Operates both on expressions and matrices. By transferring some burden of algebraic manipulations from human analyst to computer, program reduces tedium analysis and conequent opportunity for errors.

  12. Considerations of Methods of Improving Helicopter Efficiency

    NASA Technical Reports Server (NTRS)

    Dingeldein, Richard C.

    1961-01-01

    Recent NASA helicopter research indicates that significant improvements in hovering efficiency, up to 7 percent, are available from the use of a special airfoil section formed by combining an NACA 632A015 thickness distribution with an NACA 230 mean line. This airfoil should be considered for flying-crane-type helicopters. Application of standard leading-edge roughness causes a large drop in efficiency; however, the cambered rotor is shown to retain its superiority over a rotor having a symmetrical airfoil when both rotors have leading-edge roughness. A simple analysis of available rotor static-thrust data indicates a greatly reduced effect of compressibility effects on the rotor profile-drag power than predicted from calculations. Preliminary results of an experimental study of helicopter parasite drag indicate the practicability of achieving an equivalent flat-plate parasite-drag area of less than 4 square feet for a rotor-head-pylon-fuselage configuration (landing gear retracted) in the 2,000-pound minimum-flying-weight class. The large drag penalty of a conventional skid-type landing (3.6 square feet) can be reduced by two-thirds by careful design. Clean, fair, and smooth fuselages that tend to have narrow, deep cross sections are shown to have advantages from the standpoint of drag and download. A ferry range of the order of 1,500 miles is indicated to be practicable for the small helicopter considered.

  13. Helicopter emergency medical services (doctor-helicopter) in Fukushima Prefecture: present state and problems.

    PubMed

    Tase, Choichiro; Ohno, Yuko; Hasegawa, Arifumi; Tsukada, Yasuhiro; Shimada, Jiro; Ikegami, Yukihiro

    2010-06-01

    The purpose of this study is to identify the problems in operating an emergency medical service helicopter with an emergency medicine doctor on board (doctor-helicopter) in Fukushima Prefecture, Japan, which covers wide regions and many rural areas. The study looked at the numbers of flights and patients during the 523 days since the start of the doctor-helicopter service at the Fukushima Medical University Hospital. The items investigated were: number of flights, number of helicopter dispatches per month, number of patients, the hospitals where patients were taken to, the fire department dispatch centers that requested the doctor-helicopter, and the number of times each doctor flew on the helicopter. There were 450 flights. When the service was started, there were a few flights, but they gradually increased. The majority of the flights were to emergency scenes (295), while 75 flights were interfacility transports of critically ill patients, 79 flights were cancelled after take-off, and one flight was for a disaster relief operation. The nature of requests differed greatly depending on the fire department dispatch center requesting the service. The majority of patients were trauma patients (62.2%). Stroke (8.5%) and acute coronary syndrome (5.2%) patients requiring emergency treatment were fewer than anticipated. The final destination hospitals were appropriate hospitals in the region. Because the number of flight doctors is small, the burden on individual doctors is large. A system for early on-site diagnosis and helicopter request by emergency rescue team is required to maintain a high quality of emergency care.

  14. Helicopter gearbox isolation using periodically layered fluidic isolators

    NASA Astrophysics Data System (ADS)

    Szefi, Joseph Thomas

    2003-07-01

    In rotorcraft transmissions, vibration generation by meshing gear pairs is a significant source of vibration and cabin noise. This high-frequency gearbox noise is primarily transmitted to the fuselage through rigid connections, which do not appreciably attenuate vibratory energy. The high-frequency vibrations typically include discrete gear-meshing frequencies in the range of 500--2000 Hz, and are often considered irritating and can reduce pilot effectiveness and passenger comfort. Periodically-layered isolators were identified as potential passive attenuators of these high frequency vibrations. Layered isolators exhibit transmissibility "stop bands," or frequency ranges in which there is very low transmissibility. An axisymmetric model was developed to accurately predict the location of these stop bands for isolators in compression. A Ritz approximation method was used to model the axisymmetric elastic behavior of layered cylindrical isolators. This model of layered isolators was validated with experiments. The physical design constraints of the proposed helicopter gearbox isolators were then estimated. Namely, constraints associated with isolator mass, axial stiffness, geometry, and elastomeric fatigue were determined. The passive performance limits of layered isolators were then determined using a design optimization methodology employing a simulated annealing algorithm. The results suggest that layered isolators cannot always meet frequency targets given a certain set of design constraints. Many passive and active design enhancements were considered to address this problem, and the use of embedded inertial amplifiers was found to exhibit a combination of advantageous effects. The first benefit was a lowering of the beginning stop band frequency, and thus a widening of the original stop band. The second was a tuned absorber effect, where the elastomer layer stiffness and the amplified tuned mass combined to act as a vibration absorber within the stop band. The

  15. Subjective field study of response to impulsive helicopter noise

    NASA Technical Reports Server (NTRS)

    Powell, C. A.

    1981-01-01

    Subjects, located outdoors and indoors, judged the noisiness and other subjective noise characteristics of flyovers of two helicopters and a propeller driven airplane as part of a study of the effects of impulsiveness on the subjective response to helicopter noise. In the first experiment, the impulsive characteristics of one helicopter was controlled by varying the main rotor speed while maintaining a constant airspeed in level flight. The second experiment which utilized only the helicopters, included descent and level flight operations. The more impulsive helicopter was consistently judged less noisy than the less impulsive helicopter at equal effective perceived noise levels (EPNL). The ability of EPNL to predict noisiness was not improved by the addition of either of two proposed impulse corrections. A subjective measure of impulsiveness, however, which was not significantly related to the proposed impulse corrections, was found to improve the predictive ability of EPNL.

  16. Helicopter Control Energy Reduction Using Moving Horizontal Tail

    PubMed Central

    Oktay, Tugrul; Sal, Firat

    2015-01-01

    Helicopter moving horizontal tail (i.e., MHT) strategy is applied in order to save helicopter flight control system (i.e., FCS) energy. For this intention complex, physics-based, control-oriented nonlinear helicopter models are used. Equations of MHT are integrated into these models and they are together linearized around straight level flight condition. A specific variance constrained control strategy, namely, output variance constrained Control (i.e., OVC) is utilized for helicopter FCS. Control energy savings due to this MHT idea with respect to a conventional helicopter are calculated. Parameters of helicopter FCS and dimensions of MHT are simultaneously optimized using a stochastic optimization method, namely, simultaneous perturbation stochastic approximation (i.e., SPSA). In order to observe improvement in behaviors of classical controls closed loop analyses are done. PMID:26180841

  17. Finite difference time domain grid generation from AMC helicopter models

    NASA Technical Reports Server (NTRS)

    Cravey, Robin L.

    1992-01-01

    A simple technique is presented which forms a cubic grid model of a helicopter from an Aircraft Modeling Code (AMC) input file. The AMC input file defines the helicopter fuselage as a series of polygonal cross sections. The cubic grid model is used as an input to a Finite Difference Time Domain (FDTD) code to obtain predictions of antenna performance on a generic helicopter model. The predictions compare reasonably well with measured data.

  18. Combat Maintenance Concepts and Repair Techniques for Helicopter Airframe Structures

    DTIC Science & Technology

    1981-01-01

    helicopter airframe and to de- velop concepts for the assessment and repair of airframe combat damage. A computer model was developed to generate...random simulated hallistic strikes on the Black Hawk helicopter airframe. Random shotlines were generated with the model , and cases involving damage...Distribution of Ballistic Hits on Helicopters from Southeast Asia Combat Experience 23 Shotline Simulation Model 24 Conventions for Azimuth and

  19. Economic Effects of Noise Abatement Regulations on the Helicopter Industry.

    DTIC Science & Technology

    1982-12-01

    are estimated. The effects an consumer utilization are also discussed. An appendix compares two independent research studies that used weight...helicopter by subsystem. This thesis proposes that if noise abatement regulations are iqposed on the helicopter industry without due consideration for future...abatement regu- lations on Sikorsky’s s-7S helicopter are estimated. The effects on consumer utilization are also discussed. kn appendix compares two

  20. Helicopter mission optimization study. [portable computer technology for flight optimization

    NASA Technical Reports Server (NTRS)

    Olson, J. R.

    1978-01-01

    The feasibility of using low-cost, portable computer technology to help a helicopter pilot optimize flight parameters to minimize fuel consumption and takeoff and landing noise was demonstrated. Eight separate computer programs were developed for use in the helicopter cockpit using a hand-held computer. The programs provide the helicopter pilot with the ability to calculate power required, minimum fuel consumption for both range and endurance, maximum speed and a minimum noise profile for both takeoff and landing. Each program is defined by a maximum of two magnetic cards. The helicopter pilot is required to key in the proper input parameter such as gross weight, outside air temperature or pressure altitude.

  1. Research requirements to improve safety of civil helicopters

    NASA Technical Reports Server (NTRS)

    Waters, K. T.

    1977-01-01

    Helicopter and fixed-wing accident data were reviewed and major accident causal factors were established. The impact of accidents on insurance rates was examined and the differences in fixed-wing and helicopter accident costs discussed. The state of the art in civil helicopter safety was compared to military helicopters. Goals were established based on incorporation of known technology and achievable improvements that require development, as well as administrative-type changes such as the impact of improved operational planning, training, and human factors effects. Specific R and D recommendations are provided with an estimation of the payoffs, timing, and development costs.

  2. NASA helicopter blades get new paint job for safety

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Workers put the finishing touches on new paint for the blades of a NASA UH-1H helicopter. They have changed the black to a pattern of white and yellow stripes. The pattern provides better visibility in smoke and fire conditions. When the rotors are turning, the stripes create a yellow and white circle that is more easily seen from above by a second helicopter. The helicopters, primarily used for security and medical evacuation for NASA, will be used to deliver water via buckets during brush fires. The change was made to comply with U.S. Fish and Wildlife and Department of Forestry regulations for helicopter-assisted fire control.

  3. NASA helicopter blades get new paint job for safety

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Workers paint the blades of a NASA UH-1H helicopter, changing the black to a pattern of white and yellow stripes. The pattern provides better visibility in smoke and fire conditions. When the rotors are turning, the stripes create a yellow and white circle that is more easily seen by a second helicopter from above. The helicopters, primarily used for security and medical evacuation for NASA, will be used to deliver water via buckets during brush fires. The change was made to comply with U.S. Fish and Wildlife and Department of Forestry regulations for helicopter-assisted fire control.

  4. Automatic guidance and control laws for helicopter obstacle avoidance

    NASA Technical Reports Server (NTRS)

    Cheng, Victor H. L.; Lam, T.

    1992-01-01

    The authors describe the implementation of a full-function guidance and control system for automatic obstacle avoidance in helicopter nap-of-the-earth (NOE) flight. The guidance function assumes that the helicopter is sufficiently responsive so that the flight path can be readily adjusted at NOE speeds. The controller, basically an autopilot for following the derived flight path, was implemented with parameter values to control a generic helicopter model used in the simulation. Evaluation of the guidance and control system with a 3-dimensional graphical helicopter simulation suggests that the guidance has the potential for providing good and meaningful flight trajectories.

  5. 78 FR 44045 - Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ... Corporation (Sikorsky) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of... directive (AD): Sikorsky Aircraft Corporation (Sikorsky): Docket No. FAA-2013-0636; Directorate...

  6. The saber microwave-powered helicopter project and related WPT research at the University of Alaska Fairbanks

    NASA Astrophysics Data System (ADS)

    Hawkins, Joe; Houston, Shawn; Hatfield, Michael; Brown, William

    1998-01-01

    This paper describes the current status of three projects at the University of Alaska Fairbanks with potential applications to Solar Power Satellites (SPS). The Semi-Autonomous BEam Rider (SABER) project is a model helicopter powered by a 1 horsepower electric motor and a rotor with a diameter of 1.15 m. It receives the power necessary to hover from a 1 kW microwave transmitter operating at 2.45 GHz. This project is intended to provide a test bed for development of Wireless Power Transmission (WPT) technology and an easily transportable demonstration of this technology. The power is received by an array of rectenna elements mounted beneath the helicopter. The ultimate goal is to integrate sensor and control subsystems onto the helicopter to measure the helicopter's attitude and position, and allow it to autonomously hover over the incident microwave beam. A second project consists of the continued refinement of a Magnetron Directional Amplifier (MDA) to provide an efficient, high power microwave source with independent control of phase and amplitude. Several MDA modules may be combined to provide an electronically-steerable phased array antenna in the future. A third project consists of computer simulations and optimization of sparse array antennas for SPS applications.

  7. Advanced rotorcraft transmission program

    NASA Technical Reports Server (NTRS)

    Bill, Robert C.

    1990-01-01

    The Advanced Rotorcraft Transmission (ART) program is an Army-funded, joint Army/NASA program to develop and demonstrate lightweight, quiet, durable drivetrain systems for next generation rotorcraft. ART addresses the drivetrain requirements of two distinct next generation aircraft classes: Future Air Attack Vehicle, a 10,000 to 20,000 lb. aircraft capable of undertaking tactical support and air-to-air missions; and Advanced Cargo Aircraft, a 60,000 to 80,000 lb. aircraft capable of heavy life field support operations. Both tiltrotor and more conventional helicopter configurations are included in the ART program. Specific objectives of ART include reduction of drivetrain weight by 25 percent compared to baseline state-of-the-art drive systems configured and sized for the next generation aircraft, reduction of noise level at the transmission source by 10 dB relative to a suitably sized and configured baseline, and attainment of at least a 5000 hr mean-time-between-removal. The technical approach for achieving the ART goals includes application of the latest available component, material, and lubrication technology to advanced concept drivetrains that utilize new ideas in gear configuration, transmission layout, and airframe/drivetrain integration. To date, candidate drivetrain systems were carried to a conceptual design stage, and tradeoff studies were conducted resulting in selection of an ART transmission configuration for each of the four contractors. The final selection was based on comparative weight, noise, and reliability studies. A description of each of the selected ART designs is included. Preliminary design of each of the four selected ART transmission was completed, as have mission impact studies wherein comparisons of aircraft mission performance and life cycle costs are undertaken for the next generation aircraft with ART and with the baseline transmission.

  8. Flight service evaluation of composite helicopter components

    NASA Technical Reports Server (NTRS)

    Rich, M. J.; Lowry, D. W.

    1982-01-01

    This first interim report presents the technical background for including environmental effects in the design of helicopter composite structures, and test results after approximately two year field exposure of components and panels. Composite structural components were removed from Sikorsky S-76 helicopters commercially operated in the Gulf Coast region of Louisiana. Fatigue tests were conducted for a graphite/epoxy tail rotor spar and static test for a graphite/epoxy and Kevlar/epoxy stabilizer. Graphite/epoxy and Kevlar/epoxy panels are being exposed to the outdoor environment in Stratford, Connecticut and West Palm Beach, Florida. For this reporting period the two year panels were returned, moisture measurements taken, and strength tests conducted. Results are compared with initial type certificate strengths for components and with initial laboratory coupon tests for the exposed panels. Comparisons are also presented with predicted and measured moisture contents.

  9. Effect of helicopter noise on passenger annoyance

    NASA Technical Reports Server (NTRS)

    Clevenson, S. A.; Leatherwood, J. D.

    1979-01-01

    The effects of helicopter interior noise on passenger annoyance for both reverie and listening situations was investigated. The relative effectiveness of several metrics for quantifying annoyance response for these situations was also studied. The noise stimuli were based upon recordings of the interior noise of civil helicopter research aircraft. These noises were presented at levels ranging from approximately 70 to 86 d with various tonal components selectively attenuated to give a range of spectra. The listening task required the subjects to listen to and record phonetically-balanced words presented within the various noise environments. Results indicate that annoyance during a listening condition is generally higher than annoyance under a reverie condition for corresponding interior noise environments. Attenuation of the tonal components results in increases in listening performance but has only a small effect upon annoyance for a given noise level.

  10. NASA/FAA helicopter simulator workshop

    NASA Technical Reports Server (NTRS)

    Larsen, William E. (Editor); Randle, Robert J., Jr. (Editor); Bray, Richard S. (Editor); Zuk, John (Editor)

    1992-01-01

    A workshop was convened by the FAA and NASA for the purpose of providing a forum at which leading designers, manufacturers, and users of helicopter simulators could initiate and participate in a development process that would facilitate the formulation of qualification standards by the regulatory agency. Formal papers were presented, special topics were discussed in breakout sessions, and a draft FAA advisory circular defining specifications for helicopter simulators was presented and discussed. A working group of volunteers was formed to work with the National Simulator Program Office to develop a final version of the circular. The workshop attracted 90 individuals from a constituency of simulator manufacturers, training organizations, the military, civil regulators, research scientists, and five foreign countries.

  11. Helmet mounted display systems for helicopter simulation

    NASA Technical Reports Server (NTRS)

    Haworth, Loran A.; Bucher, Nancy; Runnings, David

    1989-01-01

    Simulation scientists continually pursue improved flight simulation technology with the goal of closely replicating the 'real world' physical environment. The presentation/display of visual information for flight simulation is one such area enjoying recent technical improvements that are fundamental for conducting simulated operations close to the terrain. Detailed and appropriate visual information is especially critical for Nap-Of-the-Earth (NOE) helicopter flight simulation where the pilot maintains an 'eyes-out' orientation to avoid obstructions and terrain. This paper elaborates on the visually coupled Wide Field Of View Helmet Mounted Display (WFOVHMD) system technology as a viable visual display system for helicopter simulation. In addition the paper discusses research conducted on the NASA-Ames Vertical Motion Simulator that examined one critical research issue for helmet mounted displays.

  12. Evaluation of Navy 9 cst Oil in Bell Helicopter M412 HP Gearboxes

    NASA Technical Reports Server (NTRS)

    Zachary, S. H.; Stapper, William R.

    1998-01-01

    Tests were conducted with 5 and 9 centistoke lubricants in three different helicopter gearboxes, a main transmission, a 42' gearbox and a tailrotor gearbox. The objective of the tests was to observe and measure the difference in the performance of the lubrication systems due to the viscosity difference between the two test lubricants. The 9 centistoke oil has been developed to provide higher component film thickness, increased load carrying capacity and improved corrosion resistance which will provide increased life for drive system gears and bearings.

  13. Helicopter low-speed yaw control

    NASA Technical Reports Server (NTRS)

    Wilson, John C. (Inventor); Kelley, Henry L. (Inventor); Crowell, Cynthia A. (Inventor)

    1993-01-01

    A system for improving yaw control at low speeds consists of one strake placed on the upper portion of the fuselage facing the retreating rotor blade and another strake placed on the lower portion of the fuselage facing the advancing rotor blade. These strakes spoil the airflow on the helicopter tail boom during hover, low speed flight, and right or left sidewards flight so that less side thrust is required from the tail rotor.

  14. Helicopter crew/passenger vibration sensitivity -

    NASA Technical Reports Server (NTRS)

    Gabel, R.; Reed, D. A.

    1972-01-01

    Helicopter crew and passenger vibration sensitivity are presented. Pilot subjective ratings are established for discrete frequencies and the impact of combinations of harmonic frequencies is examined. A passenger long term comfort level and a short term limit are defined for discrete frequencies and compared with pilot ratings. The results show reasonable agreement between pilot and passenger. Subjective comfort levels obtained for mixed frequency environments clearly demonstrate the need for a multi-frequency criterion.

  15. Feasibility of Helicopter Support Seek Frost.

    DTIC Science & Technology

    1980-05-01

    of helicopters in this function as a straight forward appiication. Our past and current work activity has required solutions to the type of problems ...climatic conditions permitted, the problems associated, the capabilities thus proven, and the plans for the future. In view of the growing need for more...more of a visibility problem . Again, this can be obviated by climbing to higher altitudes. Performance Effect Based on the initial trials, the British

  16. Detection And Avoidance Of Obstacles By Helicopters

    NASA Technical Reports Server (NTRS)

    Cheng, Victor H. L.; Sridhar, Banavar

    1992-01-01

    Report discusses problems relevant to control subsystems enabling helicopters on nap-of-the-Earth flight paths to detect and avoid obstacles automatically. Indicates similarities between this and obstacle-avoidance problem of industrial mobile robots. Two approaches extend two-dimensional obstacle-avoidance concept to three dimensions. First involves direct search of three-dimensional range-map data for indications of openings between obstacles. Second involves compression of data into two-dimensional map for path search.

  17. Autonomous vertical autorotation for unmanned helicopters

    NASA Astrophysics Data System (ADS)

    Dalamagkidis, Konstantinos

    Small Unmanned Aircraft Systems (UAS) are considered the stepping stone for the integration of civil unmanned vehicles in the National Airspace System (NAS) because of their low cost and risk. Such systems are aimed at a variety of applications including search and rescue, surveillance, communications, traffic monitoring and inspection of buildings, power lines and bridges. Amidst these systems, small helicopters play an important role because of their capability to hold a position, to maneuver in tight spaces and to take off and land from virtually anywhere. Nevertheless civil adoption of such systems is minimal, mostly because of regulatory problems that in turn are due to safety concerns. This dissertation examines the risk to safety imposed by UAS in general and small helicopters in particular, focusing on accidents resulting in a ground impact. To improve the performance of small helicopters in this area, the use of autonomous autorotation is proposed. This research goes beyond previous work in the area of autonomous autorotation by developing an on-line, model-based, real-time controller that is capable of handling constraints and different cost functions. The approach selected is based on a non-linear model-predictive controller, that is augmented by a neural network to improve the speed of the non-linear optimization. The immediate benefit of this controller is that a class of failures that would otherwise result in an uncontrolled crash and possible injuries or fatalities can now be accommodated. Furthermore besides simply landing the helicopter, the controller is also capable of minimizing the risk of serious injury to people in the area. This is accomplished by minimizing the kinetic energy during the last phase of the descent. The presented research is designed to benefit the entire UAS community as well as the public, by allowing for safer UAS operations, which in turn also allow faster and less expensive integration of UAS in the NAS.

  18. Fatigue life estimates for helicopter loading spectra

    NASA Technical Reports Server (NTRS)

    Khosrovaneh, A. K.; Dowling, N. E.; Berens, A. P.; Gallagher, J. P.

    1989-01-01

    Helicopter loading histories applied to notch metal samples are used as examples, and their fatigue lives are calculated by using a simplified version of the local strain approach. This simplified method has the advantage that it requires knowing the loading history in only the reduced form of ranges and means and number of cycles from the rain-flow cycle counting method. The calculated lives compare favorably with test data.

  19. Analysis of muscle fatigue in helicopter pilots.

    PubMed

    Balasubramanian, Venkatesh; Dutt, Ashwani; Rai, Shobhit

    2011-11-01

    Helicopter pilots espouse ergonomically unfavourable postures and endure vibration which result in low back pain. The objective of this study was to investigate the effects of a helicopter flight on pilots back and shoulder muscles using surface Electromyography (sEMG) analysis. This study also correlates low back pain symptoms from Rehabilitation Bioengineering Group Pain Scale (RBGPS) questionnaire with muscle fatigue rates obtained. RBGPS was administered on 20 Coast Guard helicopter pilots. sEMG was acquired before and after flight from erector spinae and trapezius muscles in 8 of these 20 pilots. Statistical analysis of time and frequency domain parameters indicated significant fatigue in right trapezius muscle due to flying. Muscle fatigue correlated with average duration of flight (r² = 0.913), total service as pilot (r² = 0.825), pain (r² = 0.463) and total flying hours (r² = 0.507). However, muscle fatigue weakly correlated with Body Mass Index (BMI) (r² = 0.000144) and age (r² = 0.033).

  20. Helicopter Airborne Laser Positioning System (HALPS)

    NASA Technical Reports Server (NTRS)

    Eppel, Joseph C.; Christiansen, Howard; Cross, Jeffrey; Totah, Joseph

    1990-01-01

    The theory of operation, configuration, laboratory, and ground test results obtained with a helicopter airborne laser positioning system developed by Princeton University is presented. Unfortunately, due to time constraints, flight data could not be completed for presentation at this time. The system measures the relative position between two aircraft in three dimensions using two orthogonal fan-shaped laser beams sweeping across an array of four detectors. Specifically, the system calculates the relative range, elevation, and azimuth between an observation aircraft and a test helicopter with a high degree of accuracy. The detector array provides a wide field of view in the presence of solar interference due to compound parabolic concentrators and spectral filtering of the detector pulses. The detected pulses and their associated time delays are processed by the electronics and are sent as position errors to the helicopter pilot who repositions the aircraft as part of the closed loop system. Accuracies obtained in the laboratory at a range of 80 ft in the absence of sunlight were + or - 1 deg in elevation; +0.5 to -1.5 deg in azimuth; +0.5 to -1.0 ft in range; while elevation varied from 0 to +28 deg and the azimuth varied from 0 to + or - 45 deg. Accuracies in sunlight were approximately 40 deg (+ or - 20 deg) in direct sunlight.

  1. Automated Power Assessment for Helicopter Turboshaft Engines

    NASA Technical Reports Server (NTRS)

    Simon, Donald L.; Litt, Jonathan S.

    2008-01-01

    An accurate indication of available power is required for helicopter mission planning purposes. Available power is currently estimated on U.S. Army Blackhawk helicopters by performing a Maximum Power Check (MPC), a manual procedure performed by maintenance pilots on a periodic basis. The MPC establishes Engine Torque Factor (ETF), an indication of available power. It is desirable to replace the current manual MPC procedure with an automated approach that will enable continuous real-time assessment of available power utilizing normal mission data. This report presents an automated power assessment approach which processes data currently collected within helicopter Health and Usage Monitoring System (HUMS) units. The overall approach consists of: 1) a steady-state data filter which identifies and extracts steady-state operating points within HUMS data sets; 2) engine performance curve trend monitoring and updating; and 3) automated ETF calculation. The algorithm is coded in MATLAB (The MathWorks, Inc.) and currently runs on a PC. Results from the application of this technique to HUMS mission data collected from UH-60L aircraft equipped with T700-GE-701C engines are presented and compared to manually calculated ETF values. Potential future enhancements are discussed.

  2. Helicopter immobilization of elk in southcentral Washington

    SciTech Connect

    McCorquodale, S.M.; Eberhardt, L.E. ); Petron, S.E. )

    1988-01-01

    Free-ranging elk are commonly immobilized for research or management by rifle-fired darts shot from a helicopter. Compounds used for this purpose have included succinylcholine chloride (succinylcholine), etorphine hydrochloride (etorphine), and xylazine hydrochloride (xylazine). To assess the efficacy of various immobilizing drugs used in helicopter applications, we darted 38 elk from a helicopter on the Arid Lands Ecology Reserve, Washington from 1983 to 1987. We used either succinylcholine, etorphine hydrochloride, or xylazine hydrochloride a primary immobilants. Unsuccessful immobilizations were most common in elk darted with succinylcholine. Yohimbine was used to reverse xylazine immobilizations. The use of xylazine and yohimbine provides an efficient, cost-effective alternative to etorphine, diprenorphine immobilization and reversal in elk while increasing handler safety. Etorphine appeared to be the best immobilant when extended pain-producing procedures (such as surgical telemetry implantation) are planned because it induced the longest and deepest anesthesia. When the potential to lose contact with darted animals exist, we believe succinylcholine may be the preferred immobilant because of rapid, spontaneous recovery.

  3. Aeromechanics Analysis of a Compound Helicopter

    NASA Technical Reports Server (NTRS)

    Yeo, Hyeonsoo; Johnson, Wayne

    2006-01-01

    A design and aeromechanics investigation was conducted for a 100,000-lb compound helicopter with a single main rotor, which is to cruise at 250 knots at 4000 ft/95 deg F condition. Performance, stability, and control analyses were conducted with the comprehensive rotorcraft analysis CAMRAD II. Wind tunnel test measurements of the performance of the H-34 and UH-1D rotors at high advance ratio were compared with calculations to assess the accuracy of the analysis for the design of a high speed helicopter. In general, good correlation was obtained with the increase of drag coefficients in the reverse flow region. An assessment of various design parameters (disk loading, blade loading, wing loading) on the performance of the compound helicopter was made. Performance optimization was conducted to find the optimum twist, collective, tip speed, and taper using the comprehensive analysis. Blade twist was an important parameter on the aircraft performance and most of the benefit of slowing the rotor occurred at the initial 20 to 30% reduction of rotor tip speed. No stability issues were observed with the current design and the control derivatives did not change much with speed, but did exhibit significant coupling.

  4. Optimum Design of a Compound Helicopter

    NASA Technical Reports Server (NTRS)

    Yeo, Hyeonsoo; Johnson, Wayne

    2006-01-01

    A design and aeromechanics investigation was conducted for a 100,000-lb compound helicopter with a single main rotor, which is to cruise at 250 knots at 4000 ft/95 deg F condition. Performance, stability, and control analyses were conducted with the comprehensive rotorcraft analysis CAMRAD II. Wind tunnel test measurements of the performance of the H-34 and UH-1D rotors at high advance ratio were compared with calculations to assess the accuracy of the analysis for the design of a high speed helicopter. In general, good correlation was obtained when an increase of drag coefficients in the reverse flow region was implemented. An assessment of various design parameters (disk loading, blade loading, wing loading) on the performance of the compound helicopter was conducted. Lower wing loading (larger wing area) and higher blade loading (smaller blade chord) increased aircraft lift-to-drag ratio. However, disk loading has a small influence on aircraft lift-to-drag ratio. A rotor parametric study showed that most of the benefit of slowing the rotor occurred at the initial 20 to 30% reduction of the advancing blade tip Mach number. No stability issues were observed with the current design. Control derivatives did not change significantly with speed, but the did exhibit significant coupling.

  5. High-integrity databases for helicopter operations

    NASA Astrophysics Data System (ADS)

    Pschierer, Christian; Schiefele, Jens; Lüthy, Juerg

    2009-05-01

    Helicopter Emergency Medical Service missions (HEMS) impose a high workload on pilots due to short preparation time, operations in low level flight, and landings in unknown areas. The research project PILAS, a cooperation between Eurocopter, Diehl Avionics, DLR, EADS, Euro Telematik, ESG, Jeppesen, the Universities of Darmstadt and Munich, and funded by the German government, approached this problem by researching a pilot assistance system which supports the pilots during all phases of flight. The databases required for the specified helicopter missions include different types of topological and cultural data for graphical display on the SVS system, AMDB data for operations at airports and helipads, and navigation data for IFR segments. The most critical databases for the PILAS system however are highly accurate terrain and obstacle data. While RTCA DO-276 specifies high accuracies and integrities only for the areas around airports, HEMS helicopters typically operate outside of these controlled areas and thus require highly reliable terrain and obstacle data for their designated response areas. This data has been generated by a LIDAR scan of the specified test region. Obstacles have been extracted into a vector format. This paper includes a short overview of the complete PILAS system and then focus on the generation of the required high quality databases.

  6. Investigation of Gear and Bearing Fatigue Damage Using Debris Particle Distributions

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Lewicki, David G.; Decker, Harry J.

    2004-01-01

    A diagnostic tool was developed for detecting fatigue damage to spur gears, spiral bevel gears, and rolling element bearings. This diagnostic tool was developed and evaluated experimentally by collecting oil debris data from fatigue tests performed in the NASA Glenn Spur Gear Fatigue Rig, Spiral Bevel Gear Test Facility, and the 500hp Helicopter Transmission Test Stand. During each test, data from an online, in-line, inductance type oil debris sensor was monitored and recorded for the occurrence of pitting damage. Results indicate oil debris alone cannot discriminate between bearing and gear fatigue damage.

  7. Tracking Helicopters with a Seismic Array

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Lokmer, Ivan; Bean, Christopher J.; Akerlie, Eggert

    2015-04-01

    We observed that the pressure or acoustic wave created by the rotor blades of a helicopter can couple to the ground even at 30 km distance where it creates a signal strong enough to be detected by a seismometer. The signal is harmonic tremor with a fundamental frequency downgliding with the inflection point at e.g. 14 Hz and two equally spaced overtones up to the Nyquist frequency of 50 Hz. No difference in the amplitudes between the fundamental frequency and higher harmonics was observed. Such a signature is a consequence of the regularly repeating pressure pulses generated by the helicopter's rotor blades. The signal was recorded by a seven station broadband array with an aperture of 1.6 km. Our spacing is close enough to record the signal at all stations and far enough to observe traveltime differences. The separation of the spectral lines corresponds to the time interval between the repeating sources. The highlighted harmonics contain information about the spectral content of the single source as our signal corresponds to the convolution of an infinite comb function and a single pulse. As we see all harmonics and they have the same amplitude up to the Nyquist frequency we can deduce that the frequency content of the single pulse is flat i.e. it is effectively a delta function up to the Nyquist frequency. We perform a detailed spectral and location analysis of the signal, and compare our results with the known information on the helicopter's speed, location, the frequency of the blades rotation and the amount of blades. This analysis is based on the characteristic shape of the curve i.e. speed of the gliding, minimum and maximum fundamental frequency, amplitudes at the inflection points at different stations and traveltimes deduced from the inflection points at different stations. This observation has an educative value, because the same principle could be used for the analysis of the volcanic harmonic tremor. Harmonic volcanic tremor usually has fundamental

  8. Scoop attachment makes helicopter recoveries easier and safer

    NASA Technical Reports Server (NTRS)

    Koons, W. E.

    1965-01-01

    Helicopter with rigid boom and net attachment performs rescue or recovery operations easily and safely. The attachment in the front of the helicopter scoops objects from difficult and otherwise inaccessible areas and pivots to the side hatch of the aircraft so that no crew member need leave the craft.

  9. Environmental Assessment: Apalachicola National Forest Helicopter Landing Zones Florida

    DTIC Science & Technology

    2003-12-01

    Use, Sustained Yield Act, "the national forests are established and shall be administered for outdoor recreation , range, timber, watershed, and...ENVIRONMENTAL ASSESSEMENT APALACHICOLA NATIONAL FOREST HELICOPTER LANDING ZONES FLORIDA MOODY AIR FORCE BASE...Assessment: Apalachicola National Forest Helicopter Landing Zones Florida 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

  10. 78 FR 23692 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-22

    ... proposed AD are intended to prevent loss of a T/R blade tab, which could result in excessive vibration and..., and that the loss of the tab leads to a significant increase in the aircraft's vibration level. As a... in excessive vibration of the helicopter and loss of control of the helicopter. (c) Comments Due...

  11. USAF Combat Rescue Helicopter: Addressing Joint Force Capability Shortfalls

    DTIC Science & Technology

    2013-04-07

    Sikorsky Will Probably Win the Combat Rescue Helicopter Contract.” (blog) Wordpress , December 18, 2012 http://xbradtc.com/2012/12/18/sikorsky-will...Posture, 112th Cong., March 2012. XBRADTC (Pseudonym). “Sikorsky Will Probably Win the Combat Rescue Helicopter Contract.” (blog) Wordpress

  12. 77 FR 58794 - Airworthiness Directives; Bell Helicopter Textron, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-24

    ... rotor (M/R) blade pitch control and subsequent loss of helicopter control. DATES: We must receive... pitch control of the main rotor blades and loss of helicopter control. FAA's Determination We are... condition exists and is likely to exist or develop on other products of these same type designs....

  13. Neural Network Based Method for Estimating Helicopter Low Airspeed

    DTIC Science & Technology

    1996-10-24

    The present invention relates generally to virtual sensors and, more particularly, to a means and method utilizing a neural network for estimating...helicopter airspeed at speeds below about 50 knots using only fixed system parameters (i.e., parameters measured or determined in a reference frame fixed relative to the helicopter fuselage) as inputs to the neural network .

  14. Astronaut James Lovell hoisted from water by recovery helicopter

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut James A. Lovell Jr., pilot of the Gemini 7 space flight, is hoisted from the water by a recovery helicopter from the Aircraft Carrier U.S.S. Wasp. Astronaut Frank Borman, command pilot, waits in the raft to be hoisted aboard the helicopter.

  15. 78 FR 66668 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-06

    ... inspecting frame number (No.) 9 for a crack. This proposed AD is prompted by a report of a crack in frame No. 9 on an AS365 helicopter. The proposed actions are intended to detect a crack and prevent loss of... a crack was discovered during the ``T'' inspection of an AS365 helicopter. The crack started at...

  16. 78 FR 9634 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-11

    ... AS350 and AS355 helicopters, to require inspecting for a crack in the control lever attachment yokes... casting of TGB casing assemblies, which may lead to cracking. A crack in the control lever attachment... AS 350 and AS 355 helicopters. EASA advises that cracks were found on some TGB casing assemblies...

  17. Basic Helicopter Handbook, Revised. AC 61-13A.

    ERIC Educational Resources Information Center

    Federal Aviation Administration (DOT), Washington, DC. Flight Standards Service.

    This technical manual was designed to assist applicants preparing for the private, commercial, and flight instructor pilot certificates with a helicopter rating. The chapters outline general aerodynamics, aerodynamics of flight, loads and load factors, function of controls, other helicopter components and their functions, introduction to the…

  18. 78 FR 17076 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... deterioration of the MRH bearing of the rotating star installed on a Model AS332L1 helicopter. The actions of this AD are intended to detect deterioration of the MRH bearing and to prevent overloading the scissor... helicopters to require a one-time inspection of the main rotor head (MRH) swash-plate upper bearing...

  19. The elaboration of a new family of helicopter blade profiles

    NASA Technical Reports Server (NTRS)

    Thibert, J. J.

    1981-01-01

    An airfoil family of helicopter rotor blades was designed. Three airfoils with thickness to chord ratios of 12, 9, and 7% were designed. Their improved performance in two dimensional rotor mockup wind tunnel tests led to testing of the tapered blades on four bladed rotors in a wind tunnel and flight tests on the Dauphin series of helicopters, confirming the expected gains.

  20. Unmanned Aerial Vehicles: Replacing the Army’s Comanche Helicopter?

    DTIC Science & Technology

    2007-11-02

    This strategic research project explores the possibility of unmanned aerial vehicles replacing the Comanche Helicopter in its doctrinal missions...capabilities of unmanned aerial vehicles , and analyzes unmanned aerial vehicles capabilities against those aviation critical tasks. This research will...Army’s current helicopters, this analysis reveals that unmanned aerial vehicles can only perform 67% of the reconnaissance critical tasks, 50% of the

  1. Model Tests on the Economy and Effectiveness of Helicopter Propellers

    NASA Technical Reports Server (NTRS)

    Munk, Max M

    1925-01-01

    The average velocity of helicopter blades relative to the air is greater than that of airplane wings. The helicopter may turn out to be more economical than the airplane wing for extreme velocities of horizontal flight, the airplane then requiring a very great speed range.

  2. The Helicopter Parent: Research toward a Typology (Part I)

    ERIC Educational Resources Information Center

    Somers, Patricia; Settle, Jim

    2010-01-01

    With 117,000 hits on a recent Google[TM] search, the phenomenon of helicopter parenting has been widely reported in the popular press. Yet the scholarly literature is anemic on the topic. This article, part one of a two-part series, presents the small body of research on helicopter parenting and describes a qualitative study of 190 participants…

  3. The Helicopter Parent (Part 2): International Arrivals and Departures

    ERIC Educational Resources Information Center

    Somers, Patricia; Settle, Jim

    2010-01-01

    The phenomenon of helicopter parenting has been widely reported, yet the research literature is anemic on the topic. Based on interviews and focus groups involving 190 academic and student services professionals, this article continues by discussing the social, psychological, economic, and cultural factors that influence helicoptering; exploring…

  4. Helicopter emergency medical service scene communications made easy.

    PubMed

    Koval, Michael

    2014-01-01

    Narrowbanding has caused numerous communication issues. The solution is to use a mutual aid frequency like 123.025. That frequency is 155.3400, and every helicopter emergency medical service operator and emergency medical service agency should name this frequency as "EMS [Emergency Medical Services] Mutual Aid" and preset this frequency for all helicopter emergency medical service scene operations.

  5. 78 FR 52407 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-23

    ... helicopters with a certain emergency flotation gear (float) installed. This AD requires inspecting the float... Eurocopter Model EC120B helicopters with a left-hand (LH) emergency flotation gear, part number (P/N) 215674...) emergency flotation gear, P/N 215675-0, 215675-1, or 215675-2 installed, fitted with a float, P/N...

  6. 78 FR 12648 - Airworthiness Directives; Robinson Helicopter Company

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ... Company AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: We propose to supersede an existing airworthiness directive (AD) for Robinson Helicopter Company... identified in this proposed AD, contact Robinson Helicopter Company, 2901 Airport Drive, Torrance, CA...

  7. 29 CFR 1926.958 - External load helicopters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false External load helicopters. 1926.958 Section 1926.958 Labor... External load helicopters. In all operations performed using a rotorcraft for moving or placing external loads, the provisions of § 1926.551 of subpart N of this part shall be complied with....

  8. 29 CFR 1926.958 - External load helicopters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false External load helicopters. 1926.958 Section 1926.958 Labor... External load helicopters. In all operations performed using a rotorcraft for moving or placing external loads, the provisions of § 1926.551 of subpart N of this part shall be complied with....

  9. 77 FR 18965 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-29

    ... Directives; Eurocopter France Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice... Eurocopter France Model SA341G helicopters. This proposed AD is prompted by an analysis and tests performed... Civile (DGAC), which is the aviation authority for France, has issued French AD No. F-2004-070, dated...

  10. 78 FR 70202 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-25

    ... coupling. This AD is prompted by a crack discovered in the area of the center cross-member at station X... helicopter fitted with the collective-to-yaw control coupling. The actions of this AD are intended to prevent... coupling. Since we issued AD No. 2010-21-01, we discovered that we included all helicopters in the...

  11. 78 FR 34288 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... could lead to failure of the MGB supporting structure, detachment of the MGB, and loss of helicopter... MGB supporting structure, detachment of the MGB, and subsequent loss of control of the helicopter. (c... change, and include supporting data. To ensure the docket does not contain duplicate comments,...

  12. 77 FR 68058 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ... Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for... Aircraft Corporation (Sikorsky) Model S-70, S-70A, S-70C, S-70C(M), and S-70C(M1) helicopters with a... service information identified in this AD, contact Sikorsky Aircraft Corporation, Attn:...

  13. On the Use of Active Higher Harmonic Blade Pitch Control for Helicopter Vibration Reduction,

    DTIC Science & Technology

    1980-06-01

    G., and Gabel, R.: Vibration Optimization of the CH-47C Helicopter Using NASTRAN . Symposium on Mathematical Modeling in Structural Engineering... helicopter . DESCRIPTION OF MODEL AND TESTS The basic wind tunnel model used in this investigation was the Structures Laboratory Aeroelastic Rotor...dynamically-scaled helicopter rotor model in which an active control system employing higher harmonic blade pitch was used for helicopter vibration

  14. The Use of Commercial Remote Sensing Systems in Predicting Helicopter Brownout Conditions

    DTIC Science & Technology

    2009-09-01

    REMOTE SENSING IN PREDICTING HELICOPTER BROWNOUT CONDITIONS by Christine Kay Rabaja September 2009 Thesis Advisor: Richard C. Olsen...Master’s Thesis 4. TITLE AND SUBTITLE The Use of Commercial Remote Sensing Systems in Predicting Helicopter Brownout Conditions 6. AUTHOR...soils susceptible to helicopter brownout . Helicopter brownout occurs when downwash disturbs the dust and sand beneath the aircraft during takeoff

  15. Advanced Rotorcraft Transmission (ART) program status

    NASA Technical Reports Server (NTRS)

    Bossler, Robert; Heath, Gregory

    1991-01-01

    Reported herein is work done on the Advanced Rotorcraft Transmission by McDonnell Douglas Helicopter Company under Army/NASA contract. The novel concept pursued includes the use of face gears for power transmission and a torque splitting arrangement. The design reduces the size and weight of the corner-turning hardware and the next reduction stage. New methods of analyzing face gears have increased confidence in their usefulness. Test gears have been designed and manufactured for power transmission testing on the NASA-Lewis spiral bevel test rig. Transmission design effort has included finite element modeling of the split torque paths to assure equal deflection under load. A finite element model of the Apache main transmission has been completed to substantiate noise prediction methods. A positive engagement overrunning clutch design is described. Test spur gears have been made by near-net-shape forging from five different materials. Three housing materials have been procured for evaluation testing.

  16. A neural network for the identification of measured helicopter noise

    NASA Technical Reports Server (NTRS)

    Cabell, R. H.; Fuller, C. R.; O'Brien, W. F.

    1991-01-01

    The results of a preliminary study of the components of a novel acoustic helicopter identification system are described. The identification system uses the relationship between the amplitudes of the first eight harmonics in the main rotor noise spectrum to distinguish between helicopter types. Two classification algorithms are tested; a statistically optimal Bayes classifier, and a neural network adaptive classifier. The performance of these classifiers is tested using measured noise of three helicopters. The statistical classifier can correctly identify the helicopter an average of 67 percent of the time, while the neural network is correct an average of 65 percent of the time. These results indicate the need for additional study of the envelope of harmonic amplitudes as a component of a helicopter identification system. Issues concerning the implementation of the neural network classifier, such as training time and structure of the network, are discussed.

  17. NASA helicopter blades get new paint job for safety

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A newly repainted NASA helicopter is transported to S.R. 3 for return to Patrick AFB. Workers painted the blades of four NASA UH-1H helicopters, changing the black to a pattern of white and yellow stripes. The pattern provides better visibility in smoke and fire conditions. When the rotors are turning, the stripes create a yellow and white circle that is more easily seen by a second helicopter from above. The helicopters, primarily used for security and medical evacuation for NASA, will be used to deliver water via buckets during brush fires. The change was made to comply with U.S. Fish and Wildlife and Department of Forestry regulations for helicopter-assisted fire control.

  18. NASA helicopter blades get new paint job for safety

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Workers get ready to move a NASA UH-1H helicopter outside. They have been painting the blades of four NASA UH-1H helicopters, changing the black to a pattern of white and yellow stripes. The pattern provides better visibility in smoke and fire conditions. When the rotors are turning, the stripes create a yellow and white circle that is more easily seen by a second helicopter from above. The helicopters, primarily used for security and medical evacuation for NASA, will be used to deliver water via buckets during brush fires. The change was made to comply with U.S. Fish and Wildlife and Department of Forestry regulations for helicopter-assisted fire control.

  19. NASA helicopter blades get new paint job for safety

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA UH-1H helicopter is prepared for transfer back to Patrick Air Force Base after being painted. The blades of four NASA UH-1H helicopters were repainted, changing the black to a pattern of white and yellow stripes. The pattern provides better visibility in smoke and fire conditions. When the rotors are turning, the stripes create a yellow and white circle that is more easily seen by a second helicopter from above. The helicopters, primarily used for security and medical evacuation for NASA, will be used to deliver water via buckets during brush fires. The change was made to comply with U.S. Fish and Wildlife and Department of Forestry regulations for helicopter-assisted fire control.

  20. 78 FR 51126 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-20

    ... 204B helicopters. This proposed AD would require inspecting the tail rotor (T/R) cable assembly for an... intended to prevent disengagement of the cable from the barrel, failure of the T/R pitch control, and... the cable, could result in disengagement of the cable, T/R pitch control failure in a fixed...

  1. 77 FR 36389 - Airworthiness Directives; Bell Helicopter Textron Canada, Limited, Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-19

    .... (ASU), Night Vision Imaging System (NVIS) lighting modified by Supplemental Type Certificate SR01383SE... unfiltered turbine outlet temperature (TOT) internal over-temperature warning light, and based on those... prevent subsequent loss of control of the helicopter. DATES: This AD is effective July 24, 2012....

  2. 78 FR 4762 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-23

    ... Textron Canada Limited (Bell) Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4; telephone (450) 437-2862 or (800) 363... based on those comments. Discussion Transport Canada Civil Aviation (TCCA) has issued AD No....

  3. 78 FR 23114 - Airworthiness Directives; Bell Helicopter Textron Canada (Bell) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-18

    ... indicated airspeed when the helicopter was tested to the cold temperature limits (-40 degrees centigrade... revealed when testing at low temperatures to minus 40 degrees Centigrade (-40 C). The TCCA advises that modification to the instrumentation is required to reflect the Vne airspeed values tested at temperatures...

  4. Analysis of Helicopter Noise Data Using International Helicopter Noise Certification Procedures,

    DTIC Science & Technology

    1986-03-01

    establishes noise levels using the basic testing, reduction and analysis procedures specified by the International Civil Aviation Organization ( ICAO ...for helicopter noise certification supplemented with some procedural refinements contained in ICAO Working Group II recommendations for incorporation...Noise levels are plotted versus the logarithm of maximum gross takeoff weight and are shown relative to the ICAO noise level limits. Data from the ICAO

  5. 78 FR 34958 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell), Model Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-11

    ... directive (AD) for the Bell Model 412, 412CF, and 412EP helicopters. The AD currently requires reidentifying... the Instructions for Continued Airworthiness (ICAs) accordingly. Since we issued the AD, we have... requirements of the existing AD impossible. This proposed AD would retain the current requirements with...

  6. 78 FR 56592 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-13

    ..., for affected Model 205A-1 helicopters, replacing the chain and cable control system with a push- pull control system. This new AD requires, for Bell Model 204B, inspecting certain chains at specified..., replacing the chain and cable control system with an airworthy tail rotor push-pull control system kit....

  7. 78 FR 12646 - Airworthiness Directives; Agusta S.p.A. and Bell Helicopter Textron Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ... 412EP helicopters with certain DART Aerospace Ltd. (Dart) high gear aft crosstubes (crosstube) installed... five separate reports of crosstube failures. The actions in this proposed AD are intended to prevent... Aerospace LTD., 1270 Aberdeen St, Hawkesbury, ON, K6A 1K7, Canada; telephone: 1 613 632 5200; Fax: 1 613...

  8. 64 FR 3819 - Airworthiness Directives; Bell Helicopter Textron, Inc. Model 212 Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-01-26

    ...-hours TIS, or that has passed an x-ray diffraction inspection in accordance with Bell Helicopter Textron... airworthy yoke assembly that has zero-hours TIS, or that has passed an x-ray diffraction inspection in... assembly (regardless of TIS) that has passed an x-ray diffraction inspection in accordance with...

  9. Development of large rotorcraft transmissions

    NASA Technical Reports Server (NTRS)

    Samanich, N. E.; Drago, R. J.; Mack, J. C.

    1984-01-01

    The U.S. Army Heavy Lift Helicopter (HLH) represents a large rotorcraft which was developed by an American aerospace company. In the early 1970's with the HLH Advanced Technology Components (ATC) program, the development of large rotorcraft transmission and drive systems was started. Failures in the spiral bevel gearing were experienced in tests because the employed method of analysis had not considered the effect of rim bending. Consequently, new gears with strengthened rims were designed and fabricated. For a more accurate prediction of the load capacity of the gears, an extensive Finite Element Method (FEM) system was developed. The U.S. Army's XCH-62 HLH aft rotor transmission was finally successfully tested at full design torque and speed. A description of the test program is provided, and the analytical program is discussed. The analytical phase includes the development of a preprocessing program which aids in the review of calculated FEM stresses.

  10. Gear tooth stress measurements of two helicopter planetary stages

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    1992-01-01

    Two versions of the planetary reduction stages from U.S. Army OH-58 helicopter main rotor transmissions were tested at NASA Lewis. One sequential and one nonsequential planetary were tested. Sun gear and ring gear teeth strains were measured, and stresses were calculated from the strains. The alternating stress at the fillet of both the loaded and unloaded sides of the teeth and at the root of the sun gear teeth are reported. Typical stress variations as the gear tooth moves through mesh are illustrated. At the tooth root location of the thin rimmed sun gear, a significant stress was produced by a phenomenon other than the passing of a planet gear. The load variation among the planets was studied. Each planet produced its own distinctive load distribution on the ring and sun gears. The load variation was less for a three planet, nonsequential design as compared to that of a four planet, sequential design. The reported results enhance the data base for gear stress levels and provide data for the validation of analytical methods.

  11. Gear tooth stress measurements of two helicopter planetary stages

    NASA Astrophysics Data System (ADS)

    Krantz, Timothy L.

    Two versions of the planetary reduction stages from U.S. Army OH-58 helicopter main rotor transmissions were tested at NASA Lewis. One sequential and one nonsequential planetary were tested. Sun gear and ring gear teeth strains were measured, and stresses were calculated from the strains. The alternating stress at the fillet of both the loaded and unloaded sides of the teeth and at the root of the sun gear teeth are reported. Typical stress variations as the gear tooth moves through mesh are illustrated. At the tooth root location of the thin rimmed sun gear, a significant stress was produced by a phenomenon other than the passing of a planet gear. The load variation among the planets was studied. Each planet produced its own distinctive load distribution on the ring and sun gears. The load variation was less for a three planet, nonsequential design as compared to that of a four planet, sequential design. The reported results enhance the data base for gear stress levels and provide data for the validation of analytical methods.

  12. Pattern classifier for health monitoring of helicopter gearboxes

    NASA Technical Reports Server (NTRS)

    Chin, Hsinyung; Danai, Kourosh; Lewicki, David G.

    1993-01-01

    The application of a newly developed diagnostic method to a helicopter gearbox is demonstrated. This method is a pattern classifier which uses a multi-valued influence matrix (MVIM) as its diagnostic model. The method benefits from a fast learning algorithm, based on error feedback, that enables it to estimate gearbox health from a small set of measurement-fault data. The MVIM method can also assess the diagnosability of the system and variability of the fault signatures as the basis to improve fault signatures. This method was tested on vibration signals reflecting various faults in an OH-58A main rotor transmission gearbox. The vibration signals were then digitized and processed by a vibration signal analyzer to enhance and extract various features of the vibration data. The parameters obtained from this analyzer were utilized to train and test the performance of the MVIM method in both detection and diagnosis. The results indicate that the MVIM method provided excellent detection results when the full range of faults effects on the measurements were included in training, and it had a correct diagnostic rate of 95 percent when the faults were included in training.

  13. Pattern classifier for health monitoring of helicopter gearboxes

    NASA Astrophysics Data System (ADS)

    Chin, Hsinyung; Danai, Kourosh; Lewicki, David G.

    1993-04-01

    The application of a newly developed diagnostic method to a helicopter gearbox is demonstrated. This method is a pattern classifier which uses a multi-valued influence matrix (MVIM) as its diagnostic model. The method benefits from a fast learning algorithm, based on error feedback, that enables it to estimate gearbox health from a small set of measurement-fault data. The MVIM method can also assess the diagnosability of the system and variability of the fault signatures as the basis to improve fault signatures. This method was tested on vibration signals reflecting various faults in an OH-58A main rotor transmission gearbox. The vibration signals were then digitized and processed by a vibration signal analyzer to enhance and extract various features of the vibration data. The parameters obtained from this analyzer were utilized to train and test the performance of the MVIM method in both detection and diagnosis. The results indicate that the MVIM method provided excellent detection results when the full range of faults effects on the measurements were included in training, and it had a correct diagnostic rate of 95 percent when the faults were included in training.

  14. Correlation of finite-element structural dynamic analysis with measured free vibration characteristics for a full-scale helicopter fuselage

    NASA Technical Reports Server (NTRS)

    Kenigsberg, I. J.; Dean, M. W.; Malatino, R.

    1974-01-01

    The correlation achieved with each program provides the material for a discussion of modeling techniques developed for general application to finite-element dynamic analyses of helicopter airframes. Included are the selection of static and dynamic degrees of freedom, cockpit structural modeling, and the extent of flexible-frame modeling in the transmission support region and in the vicinity of large cut-outs. The sensitivity of predicted results to these modeling assumptions are discussed. Both the Sikorsky Finite-Element Airframe Vibration analysis Program (FRAN/Vibration Analysis) and the NASA Structural Analysis Program (NASTRAN) have been correlated with data taken in full-scale vibration tests of a modified CH-53A helicopter.

  15. Design of helicopter rotors to noise constraints

    NASA Technical Reports Server (NTRS)

    Schaeffer, E. G.; Sternfeld, H., Jr.

    1978-01-01

    Results of the initial phase of a research project to study the design constraints on helicopter noise are presented. These include the calculation of nonimpulsive rotor harmonic and broadband hover noise spectra, over a wide range of rotor design variables and the sensitivity of perceived noise level (PNL) to changes in rotor design parameters. The prediction methodology used correlated well with measured whirl tower data. Application of the predictions to variations in rotor design showed tip speed and thrust as having the most effect on changing PNL.

  16. Prediction of helicopter rotor rotational noise

    NASA Astrophysics Data System (ADS)

    Xu, Guohua; Gao, Zheng

    1991-06-01

    Based on Farassat (1981) formulation 1A for subsonic time domain, a method is developed for predicting the rotor rotational noise, which is valid for arbitrary observer positions and all linear flight conditions. Without considering the elasticity of the blade, the retarded time equation and all of the integrands in the formulation 1A are derived and expressed as the proper form for numerical calculation. As examples, the noise calculation of the helicopter Z-8 rotor and 1/4 scale UH-1 rotor in hover are carried out. Discussions are presented on the influence of rotor parameters, such as the tip Mach number, the disk loading, and the blade airfoil.

  17. Climatic Laboratory Survey Hughes YAH-64 Helicopter

    DTIC Science & Technology

    1982-03-01

    considerations. Airflow velocity data were ob- tained with a hot wire anemometer placed 8 to 10 inches (23.3 to 25.4 cm) from the left and right...tenqeo side If noaweea7 and identify by block numboer) Environmental Testing YAH-64 Hel 4 copter Climatic Laboratory 125, 70, -25, and -50°F Nine...Deficiencies Twenty-two Shortcomings 2M AftRACTr (urama inflf Se Na ffllmny ad ideltly 57 block mmbw) Environmental testing of the YAH-64 helicopter was

  18. Analysis of potential helicopter vibration reduction concepts

    NASA Technical Reports Server (NTRS)

    Landgrebe, A. J.; Davis, M. W.

    1985-01-01

    Results of analytical investigations to develop, understand, and evaluate potential helicopter vibration reduction concepts are presented in the following areas: identification of the fundamental sources of vibratory loads, blade design for low vibration, application of design optimization techniques, active higher harmonic control, blade appended aeromechanical devices, and the prediction of vibratory airloads. Primary sources of vibration are identified for a selected four-bladed articulated rotor operating in high speed level flight. The application of analytical design procedures and optimization techniques are shown to have the potential for establishing reduced vibration blade designs through variations in blade mass and stiffness distributions, and chordwise center-of-gravity location.

  19. General equilibrium characteristics of a dual-lift helicopter system

    NASA Technical Reports Server (NTRS)

    Cicolani, L. S.; Kanning, G.

    1986-01-01

    The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.

  20. System identification techniques for helicopter higher harmonic control

    NASA Technical Reports Server (NTRS)

    Jacklin, S. A.

    1986-01-01

    This paper presents and compares several system identification techniques proposed for use with higher harmonic control algorithms designed to alleviate helicopter vibration. All method for actively controlling helicopter vibration require the knowledge of how the vibration outputs are related to the control inputs. Off-line or batch identification methods for obtaining this knowledge are presented first. Then the more advanced, adaptive identification techniques proposed to track the helicopter model parameters in flight are discussed. Considerations regarding system identifiability, identification algorithm stability, and computer implementation are also discussed.

  1. Helicopter acoustic alerting system for high-security facilities

    NASA Astrophysics Data System (ADS)

    Steadman, Robert L.; Hansen, Scott; Park, Chris; Power, Dennis

    2009-05-01

    Helicopters present a serious threat to high security facilities such as prisons, nuclear sites, armories, and VIP compounds. They have the ability to instantly bypass conventional security measures focused on ground threats such as fences, check-points, and intrusion sensors. Leveraging the strong acoustic signature inherent in all helicopters, this system would automatically detect, classify, and accurately track helicopters using multi-node acoustic sensor fusion. An alert would be generated once the threat entered a predefined 3-dimension security zone in time for security personnel to repel the assault. In addition the system can precisely identify the landing point on the facility grounds.

  2. Optical Shaft-Angle Encoder For Helicopter Rotor

    NASA Technical Reports Server (NTRS)

    Golub, Robert A.; Fitzpatrick, Fred; Dennis, Dale V.; Taylor, Bryant D.

    1993-01-01

    Angular position of helicopter rotor blade determined precisely. Accomplished by use of optical shaft-angle encoder called "256 Ring" on rotor swashplate. Each 360 degree rotation of helicopter main rotor broken down into 256 reflective segments. As rotor rotates, beam of light reflected in turn from each segment into optoelectronic system. One of 256 segments reflects larger pulse than others do. Position of rotor determined by counting number of pulses after this reference pulse. While swashplate mounting requirements unique to each type of helicopter, concept applicable to all types of rotorcraft.

  3. [Anaesthesia under unfavorable conditions - rescue helicopter].

    PubMed

    Knacke, Peer G; Gehring, Hartmut; Saur, Petra

    2011-03-01

    Rescue helicopters are used for emergency care and transport of emergency patients. The dimension of the cabin is clearly limited. A transport is carried out under spatial narrowness and high noise levels. Acoustic alarms or noises caused by the patient are hardly to be perceived, so that the view at optical alarms is necessary. Environmental conditions affect the concentration on the patient. Rearrangement maneuvers represent the most critical phases. Always the whole apparative monitoring and respirator must be in the field of view of the emergency doctor, drugs to the care must be handy to be quickly administered, the quantity of oxygen has to be observed. Infusions and option of airway management are ready to set in advance. Standardized work with the aid of algorithms and knowledge of treatment recommendations and guidelines help to prevent errors. To optimize the care of emergency patients, special training courses for the crew of rescue helicopters are offered. A training simulator to practice different scenarios and the establishment of a CIRS system are recommended.

  4. Compound cycle engine for helicopter application

    NASA Technical Reports Server (NTRS)

    Castor, Jere; Martin, John; Bradley, Curtiss

    1987-01-01

    The compound cycle engine (CCE) is a highly turbocharged, power-compounded, ultra-high-power-density, lightweight diesel engine. The turbomachinery is similar to a moderate-pressure-ratio, free-power-turbine gas turbine engine and the diesel core is high speed and a low compression ratio. This engine is considered a potential candidate for future military helicopter applications. Cycle thermodynamic specific fuel consumption (SFC) and engine weight analyses performed to establish general engine operating parameters and configurations are presented. An extensive performance and weight analysis based on a typical 2-hour helicopter (+30 minute reserve) mission determined final conceptual engine design. With this mission, CCE performance was compared to that of a contemporary gas turbine engine. The CCE had a 31 percent lower-fuel consumption and resulted in a 16 percent reduction in engine plus fuel and fuel tank weight. Design SFC of the CCE is 0.33 lb/hp-hr and installed wet weight is 0.43 lb/hp. The major technology development areas required for the CCE are identified and briefly discussed.

  5. Helicopter roll control effectiveness criteria program summary

    NASA Technical Reports Server (NTRS)

    Heffley, Robert K.; Bourne, Simon M.; Mnich, Marc A.

    1988-01-01

    A study of helicopter roll control effectiveness is summarized for the purpose of defining military helicopter handling qualities requirements. The study is based on an analysis of pilot-in-the-loop task performance of several basic maneuvers. This is extended by a series of piloted simulations using the NASA Ames Vertical Motion Simulator and selected flight data. The main results cover roll control power and short-term response characteristics. In general the handling qualities requirements recommended are set in conjunction with desired levels of flight task and maneuver response which can be directly observed in actual flight. An important aspect of this, however, is that vehicle handling qualities need to be set with regard to some quantitative aspect of mission performance. Specific examples of how this can be accomplished include a lateral unmask/remask maneuver in the presence of a threat and an air tracking maneuver which recognizes the kill probability enhancement connected with decreasing the range to the target. Conclusions and recommendations address not only the handling qualities recommendations, but also the general use of flight simulators and the dependence of mission performance on handling qualities.

  6. Helicopter pilot back pain: a preliminary study.

    PubMed

    Shanahan, D F; Reading, T E

    1984-02-01

    Because of the high prevalence of back pain experienced by U.S. Army helicopter pilots, a study was conducted to ascertain the feasibility of reproducing these symptoms in the laboratory. A mock-up of a UH-1H seat and control configuration was mounted to a multi-axis vibration simulator (MAVS). Eleven subjects were tested on the apparatus for two 120-min periods. During one period, the MAVS was programmed to reproduce vibrations recorded from a UH-1H in cruise flight. The subjects received no vibration during the other test period. All subjects reported back pain which they described as identical to the pain they experience during flight, during one or more of their test periods. There was no statistical difference between the vibration and nonvibration test conditions (p greater than 0.05) in terms of time of onset of pain or intensity of pain as measured by a visual analog scale. It appears the vibration at the frequencies and amplitudes tested plays little or no role in the etiology of the back symptoms reported by these pilots. It is proposed that the primary etiological factor for these symptoms is the poor posture pilots are obliged to assume for extended periods while operating helicopters.

  7. Flight service evaluation of composite helicopter components

    NASA Technical Reports Server (NTRS)

    Mardoian, George H.; Ezzo, Maureen B.

    1994-01-01

    This paper presents the results of a NASA funded contract and Sikorsky research and development programs to evaluate structural composite components in flight service on Sikorsky Model S-76 helicopters. Selected components were removed and tested at prescribed intervals over a nine year time frame. Four horizontal stabilizers and thirteen tail rotor spars were returned from commercial service in West Palm Beach, Florida and in the Gulf Coast region of Louisiana to determine the long term effects of operations in hot and humid climates on component performance. Concurrent with the flight component evaluation, panels of materials used in their fabrication were exposed to the environment in ground racks. Selected panels were tested annually to determine the effects of exposure on physical and mechanical properties. The results of 55,741 component flight hours and 911 months of field exposure are reported and compared with initial Federal Aviation Administration (FAA) certification data. The findings of this program have provided increased confidence in the long term durability of advanced composite materials used in helicopter structural applications.

  8. Compound cycle engine for helicopter application

    NASA Technical Reports Server (NTRS)

    Castor, Jere G.

    1986-01-01

    The Compound Cycle Engine (CCE) is a highly turbocharged, power compounded, ultra-high power density, light-weight diesel engine. The turbomachinery is similar to a moderate pressure ratio, free power turbine engine and the diesel core is high speed and a low compression ratio. This engine is considered a potential candidate for future military light helicopter applications. This executive summary presents cycle thermodynamic (SFC) and engine weight analyses performed to establish general engine operating parameters and configuration. An extensive performance and weight analysis based on a typical two hour helicopter (+30 minute reserve) mission determined final conceptual engine design. With this mission, CCE performance was compared to that of a T-800 class gas turbine engine. The CCE had a 31% lower-fuel consumption and resulted in a 16% reduction in engine plus fuel and fuel tank weight. Design SFC of the CCE is 0.33 lb-HP-HR and installed wet weight is 0.43 lbs/HP. The major technology development areas required for the CCE are identified and briefly discussed.

  9. An unsteady helicopter rotor: Fuselage interaction analysis

    NASA Technical Reports Server (NTRS)

    Lorber, Peter F.; Egolf, T. Alan

    1988-01-01

    A computational method was developed to treat unsteady aerodynamic interactions between a helicopter rotor, wake, and fuselage and between the main and tail rotors. An existing lifting line prescribed wake rotor analysis and a source panel fuselage analysis were coupled and modified to predict unsteady fuselage surface pressures and airloads. A prescribed displacement technique is used to position the rotor wake about the fuselage. Either a rigid blade or an aeroelastic blade analysis may be used to establish rotor operating conditions. Sensitivity studies were performed to determine the influence of the wake fuselage geometry on the computation. Results are presented that describe the induced velocities, pressures, and airloads on the fuselage and on the rotor. The ability to treat arbitrary geometries is demonstrated using a simulated helicopter fuselage. The computational results are compared with fuselage surface pressure measurements at several locations. No experimental data was available to validate the primary product of the analysis: the vibratory airloads on the entire fuselage. A main rotor-tail rotor interaction analysis is also described, along with some hover and forward flight.

  10. Astronauts L. Gordon Cooper Jr. hoisted up to Navy helicopter

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut L. Gordon Cooper Jr. is hoisted up to a Navy helicopter during recovery operations in the Atlantic Ocean of the Gemini 5 spacecraft. The NASA Headquarter alternative photo number is 65-H-688.

  11. 14 CFR 136.11 - Helicopter floats for over water.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... controls, and (2) The flotation system armed when the helicopter is over water and is flying at a speed that does not exceed the maximum speed prescribed in the Rotorcraft Flight Manual for flying with...

  12. A practical approach to helicopter internal noise prediction

    NASA Technical Reports Server (NTRS)

    Levine, L. S.; Defelice, J. J.

    1978-01-01

    A practical and well correlated procedure for predicting helicopter internal noise is presented. It accounts for the propagation of noise along multiple paths on an octave by octave basis. The method is sufficiently general to be applicable to conventional helicopters as well as other aircraft types, when the appropriate structural geometry, noise source strengths, and material acoustic properties are defined. A guide is provided for the prediction of various helicopter noise sources over a wide range of horsepower for use when measured data are not available. The method is applied to the prediction of the interior levels of the Civil Helicopter Research Aircraft (CHRA), both with and without soundproofing installed. Results include good correlation with measured levels and prediction of the speech interference level within 1.5 db at all conditions. A sample problem is also shown illustrating the use of the procedure. This example calculates the engine casing noise observed in the passenger cabin of the CHRA.

  13. Flight tests of IFR landing approach systems for helicopters

    NASA Technical Reports Server (NTRS)

    Bull, J. S.; Hegarty, D. M.; Peach, L. L.; Phillips, J. D.; Anderson, D. J.; Dugan, D. C.; Ross, V. L.

    1981-01-01

    Joint NASA/FAA helicopter flight tests were conducted to investigate airborne radar approaches (ARA) and microwave landing system (MLS) approaches. Flight-test results were utilized to prove NASA with a data base to be used as a performance measure for advanced guidance and navigation concepts, and to provide FAA with data for establishment of TERPS criteria. The first flight-test investigation consisted of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico, using weather/mapping radar, operational pilots, and a Bell 212 helicopter. The second flight-test investigation consisted of IFR MLS approaches at Crows Landing (near Ames Research Center), with a Bell UH-1H helicopter, using NASA, FAA, and operational industry pilots. Tests are described and results discussed.

  14. Component noise variables of a light observation helicopter

    NASA Technical Reports Server (NTRS)

    Robinson, F.

    1973-01-01

    A test program was conducted to isolate and evaluate the individual noise sources of a light helicopter. To accomplish this, the helicopter was mounted on a special test rig, at a 6-foot skid height, in a simulated hover. The test rig contained by dynamometer for absorbing engine power and an exhaust silencing system for reducing engine noise. This test set-up allowed the various components of the helicopter to be run and listened to individually or in any combination. The sound pressure level was recorded at a point 200 feet from the helicopter as the component parameters were systematically varied. The tests were conducted in an open area, during the middle of the night, with no wind, and with all other known variables either eliminated or kept as constant as possible.

  15. 78 FR 24371 - Airworthiness Directives; Robinson Helicopter Company (Robinson)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Robinson Helicopter Company (Robinson) AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed..., Aerospace Engineer, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, FAA,...

  16. 77 FR 39911 - The New York North Shore Helicopter Route

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-06

    ... and eastern shores of Long Island. Unlike helicopter traffic in urban areas, where the destination.../oaqps001/greenbk/ancl.html . In addition, the state of New York is within the Ozone Transport...

  17. 7. Shed and keeper' house with helicopter pad in foreground, ...

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

    7. Shed and keeper' house with helicopter pad in foreground, view east, southwest and northwest sides - Goat Island Light Station, Goat Island, next to entrance to Cape Porpoise Harbor, just south of Trott Island, Cape Porpoise, York County, ME

  18. 78 FR 49115 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-13

    ...-100-AD; Amendment 39-17285; AD 2012-25-04] RIN 2120-AA64 Airworthiness Directives; Eurocopter France... applies to certain Eurocopter France (Eurocopter) Model AS350B3 helicopters. The reference to Title...

  19. 77 FR 49710 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-17

    ... Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S... AD, contact Sikorsky Aircraft Corporation, Attn: Manager, Commercial Technical Support,...

  20. 77 FR 56581 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-13

    ... Directives; Sikorsky Aircraft Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT... revising an earlier proposed airworthiness directive (AD) for the Sikorsky Aircraft Corporation (Sikorsky.... For service information identified in this proposed AD, contact Sikorsky Aircraft Corporation,...

  1. 77 FR 68057 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ... Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for certain Sikorsky Aircraft Corporation (Sikorsky... service information identified in this AD, contact Sikorsky Aircraft Corporation, Attn:...

  2. 77 FR 23382 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-19

    ... Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S.... ADDRESSES: For service information identified in this AD, contact Sikorsky Aircraft Corporation,...

  3. 77 FR 68061 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-15

    ... Aircraft Corporation Helicopters AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for the Sikorsky Aircraft Corporation... service information identified in this AD, contact Sikorsky Aircraft Corporation, Attn:...

  4. Quantification of helicopter rotor downwash effects on electro-optical defensive aids suites

    NASA Astrophysics Data System (ADS)

    Seiffer, Dirk P.; Eisele, Christian; Henriksson, Markus; Sjöqvist, Lars; Möller, Sebastian; Togna, Fabio; Velluet, Marie-Thérèse

    2015-10-01

    The performance of electro-optical platform protection systems can be degraded significantly by the propagation environment around the platform. This includes aero-optical effects and zones of severe turbulence generated by engine exhausts. For helicopters rotor tip vortices and engine exhaust gases that are pressed down by the rotor airflow form the so called downwash phenomena. The downwash is a source for perturbations. A wide range of spatial and temporal fluctuations in the refractive index of air can occur. The perturbations from the turbulent flow cause detrimental effects on energy delivery, angle of arrival fluctuations, jam-code transmission, tracking accuracy and imaging performance in general. Therefore the effects may especially have a severe impact on the performance of laser-based protection systems like directed infrared countermeasures (DIRCM). The chain from passive missile detection and warning to obtaining an optical break-lock by the use of an active laser system will be influenced. To anticipate the installed performance of an electro-optical defensive aids suite (DAS) for helicopter platforms it is necessary to develop models for the prediction of the perturbations. Modelled results have to be validated against experimental findings. However, the data available in open literature on the effects of rotor downwash from helicopters on optical propagation is very limited. To collect necessary data and to obtain a first impression about the magnitude of occurring effects the European defence agency group (EDA) on "airborne platform effects on lasers and warning sensors (ALWS)" decided to design and perform a field trial on the premises of the Italian Air Force Flight Test Center in Pratica di Mare, Italy. ALWS is a technical arrangement under the Europa MoU among France, Germany, Italy, Sweden and the United Kingdom.

  5. Planetary Transmission Diagnostics

    NASA Technical Reports Server (NTRS)

    Lewicki, David G. (Technical Monitor); Samuel, Paul D.; Conroy, Joseph K.; Pines, Darryll J.

    2004-01-01

    This report presents a methodology for detecting and diagnosing gear faults in the planetary stage of a helicopter transmission. This diagnostic technique is based on the constrained adaptive lifting algorithm. The lifting scheme, developed by Wim Sweldens of Bell Labs, is a time domain, prediction-error realization of the wavelet transform that allows for greater flexibility in the construction of wavelet bases. Classic lifting analyzes a given signal using wavelets derived from a single fundamental basis function. A number of researchers have proposed techniques for adding adaptivity to the lifting scheme, allowing the transform to choose from a set of fundamental bases the basis that best fits the signal. This characteristic is desirable for gear diagnostics as it allows the technique to tailor itself to a specific transmission by selecting a set of wavelets that best represent vibration signals obtained while the gearbox is operating under healthy-state conditions. However, constraints on certain basis characteristics are necessary to enhance the detection of local wave-form changes caused by certain types of gear damage. The proposed methodology analyzes individual tooth-mesh waveforms from a healthy-state gearbox vibration signal that was generated using the vibration separation (synchronous signal-averaging) algorithm. Each waveform is separated into analysis domains using zeros of its slope and curvature. The bases selected in each analysis domain are chosen to minimize the prediction error, and constrained to have the same-sign local slope and curvature as the original signal. The resulting set of bases is used to analyze future-state vibration signals and the lifting prediction error is inspected. The constraints allow the transform to effectively adapt to global amplitude changes, yielding small prediction errors. However, local wave-form changes associated with certain types of gear damage are poorly adapted, causing a significant change in the

  6. Dynamic Exploration of Helicopter Reconnaissance Through Agent-Based Modeling

    DTIC Science & Technology

    2000-09-01

    Multi - Agent System modeling to develop a simulation of tactical helicopter performance while conducting armed reconnaissance. It focuses on creating a model to support planning for the Test and Evaluation phas of the Comanche helicopter acquisition cycle. The model serves as an initial simulation laboratory for scenario planning, requirements forecasting, and platform comparison analyses. The model implements adaptive tactical movement with agent sensory and weaponry system characteristics. Agents are able to determine their movement direction and paths based on

  7. Astronauts Stafford and Young await pickup by recovery helicopter

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronauts Thomas P. Stafford, commander; and John W. Young, command module pilot, await pickup by the recovery helicopter from the prime recovery ship, U.S.S. Pinceton. Astronaut Eugene A. Cernan, lunar module pilot, is already hoisted aboard the helicopter. U.S. Navy underwater demolition team swimmers assist in the recovery operations. Splashdown occurred at 11:53 a.m., May 26, 1969, about 400 miles east of American Samoa.

  8. Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads

    NASA Technical Reports Server (NTRS)

    Amer, K. B.; Neff, J. R.

    1974-01-01

    The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.

  9. Army Attack Helicopters: Can They Survive on the Airland Battlefield?

    DTIC Science & Technology

    1987-06-05

    air-to-ar defense sysstems were studied. Specific anti-helicopter systems and tactics were investigated to determine the level of the threat facing...most notable for its suggestion of the development of the helicopter turbine engine , which promised to be an answer to the acute engine power...Argentine Pucara. The Pucara is a small twin engined , two seat aircraft designed for counterinsurgency duties in Argentina. It is armed with two 20mm or

  10. Model-Based Sensor Selection for Helicopter Gearbox Monitoring

    DTIC Science & Technology

    1996-04-01

    fault diagnosis of helicopter gearboxes is therefore necessary to prevent major breakdowns due to progression of undetected...in the gearbox . Once the presence of a fault is prompted by the fault detection network, fault diagnosis is performed by the Structure-Based...Components Figure 3: Overview of fault detection and diagnosis in the proposed model-based di- agnostic system for helicopter gearboxes . the OH-58A gearbox

  11. Multipath Propagation for Helicopter-to-Ground MIMO Links

    DTIC Science & Technology

    2011-06-02

    AFFTC-PA-11118 Multipath Propagation for Helicopter-to-Ground MIMO Links Michael Rice, Michael Jensen AIR FORCE FLIGHT TEST CENTER...EDWARDS AFB, CA June 2, 2011 A F F T C m Approved for public release; distribution is unlimited. AIR FORCE FLIGHT TEST CENTER...TITLE AND SUBTITLE Multipath Propagation for Helicopter-to-Ground MIMO Links 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  12. Helicopter technology benefits and needs. Volume 2: Appendices

    NASA Technical Reports Server (NTRS)

    Zuk, J.; Adams, R. J.

    1980-01-01

    Vehicle design, avionics and flight systems; safety and reliability; navigation, guidance and flight control; propulsion; auxiliary systems; human factors; and monitoring and diagnostic systems are the technology areas involved in solving operational and technical problems related to the use of helicopters. Tables show the problems encountered and the proposed research and technology for helicopter use for search and rescue; emergency medical services; law enforcement; environmental control; fire fighting; and resource management.

  13. Application of a helicopter mathematical model to the Langley differential maneuvering simulator for use in a helicopter/fighter evasive maneuver study

    NASA Technical Reports Server (NTRS)

    Houck, J. A.; Ashworth, B. R.; Baker, D. R.

    1976-01-01

    A real time simulation study was conducted using a differential maneuvering simulator to determine and evaluate helicopter evasive maneuvers when attacked by fighter aircraft. A general helicopter mathematical model was modified to represent an H-53 helicopter. The helicopter model was compared to H-53 flight test data to determine any differences between the simulated and actual vehicles. The simulated helicopter was also subjectively validated by participating pilots. Two fighter mathematical models validated in previous studies were utilized for the attacking aircraft. The results of this simulation study have been verified in a flight test program conducted by the U. S. Air Force and were found to closely match the flight results.

  14. Medical considerations in the use of helicopters in mountain rescue.

    PubMed

    Tomazin, Iztok; Kovacs, Tim

    2003-01-01

    The outcome of patient care can be dramatically improved by bringing rapid rescue and medical care to the mountain rescue scene and by rapid transport to a medical facility. The use of a helicopter for these purposes is common. It is necessary when it has clear advantages for victims in comparison with ground rescue and transport. Helicopters should work within the existing emergency medical system and must be staffed by appropriate mountain rescue and medically trained personnel. Activation time should be as short as possible. Activation of a helicopter for a mountain rescue should primarily include indication and assessment of flight and safety conditions. No other mediators or delaying factors should be permitted. The main safety criteria are appropriate mountain rescue and flight training, competence of air and ground crews, radio communication between the air and ground crews, and mission briefing before the rescue. Criteria for a helicopter used for mountain rescue are proper medical and rescue equipment, load capacity, adequate space, and others. There are two main groups of indications for use of a helicopter for mountain rescue: the patient's condition and the circumstances at the site of the accident. All persons responsible for the activation of the helicopter rescue operation should be aware of specific problems in the mountains or wilderness.

  15. An evaluation of three helicopter rotor sections

    NASA Technical Reports Server (NTRS)

    Hicks, R. M.; Collins, L. J.

    1985-01-01

    Three helicopter rotor sections were tested in the NASA Ames Research Center 2- by 2-Foot Transonic Wind Tunnel over a Mach range from 0.2 to 0.88. The sections tested had maximum thickness/chord ratios of 0.078, 0.09, and 0.10. The thickest section was of early technology and had been tested previously in other wind tunnels. This section was included in the investigation to establish a basis for comparing the two thinner sections, which were of recent design. The results of the investigation showed that the pitching-moment characteristics for the three airfoil sections were acceptable. The drag divergence Mach numbers for the three sections were 0.80, 0.825, and 0.845 in order of decreasing thickness.

  16. Study of design constraints on helicopter noise

    NASA Technical Reports Server (NTRS)

    Sternfeld, H., Jr.; Wiedersum, C. W.

    1979-01-01

    A means of estimating the noise generated by a helicopter main rotor using information which is generally available during the preliminary design phase of aircraft development is presented. The method utilizes design charts and tables which do not require an understanding of acoustical theory or computational procedures in order to predict the perceived noise level, a weighted sound pressure level, or C weighted sound pressure level of a single hovering rotor. A method for estimating the effective perceived noise level in forward flight is also included. In order to give the designer an assessment of the relative rotor performance, which may be traded off against noise, an additional chart for estimating the percent of available rotor thrust which must be expended in lifting the rotor and drive system, is included as well as approach for comparing the subjective acceptability of various rotors once the absolute sound pressure levels are predicted.

  17. Helicopter Rotor Blade With Free Tip

    NASA Technical Reports Server (NTRS)

    Stroub, Robert H.; Young, Larry; Cawthorne, Matthew; Keys, Charles

    1992-01-01

    Free-tip rotor blades improve fuel efficiency and performance characteristics of helicopters. Outermost portion of blade pivots independently with respect to inboard portion about pitch axis parallel to blade axis, located forward of aerodynamic center. Centrifugal force acts on tension/torsion strap and biases tip nose-up. Airstream turns tip nose-down, other torques cause tip to "weathervane" to intermediate angular position resulting in net lift. Reduces fluctuations in lift, with two effects: flapwise vibratory loads on blade and vibratory loads on pitch-control mechanism reduced; negative lift produced by advancing fixed tip eliminated, reducing power required to achieve same overall lift. Applies to tilt rotors and tail rotors as well.

  18. Helicopter simulation validation using flight data

    NASA Technical Reports Server (NTRS)

    Key, D. L.; Hansen, R. S.; Cleveland, W. B.; Abbott, W. Y.

    1982-01-01

    A joint NASA/Army effort to perform a systematic ground-based piloted simulation validation assessment is described. The best available mathematical model for the subject helicopter (UH-60A Black Hawk) was programmed for real-time operation. Flight data were obtained to validate the math model, and to develop models for the pilot control strategy while performing mission-type tasks. The validated math model is to be combined with motion and visual systems to perform ground based simulation. Comparisons of the control strategy obtained in flight with that obtained on the simulator are to be used as the basis for assessing the fidelity of the results obtained in the simulator.

  19. Ground exposure of composite materials for helicopters

    NASA Technical Reports Server (NTRS)

    Baker, D. J.

    1984-01-01

    Residual strength results are presented on four composite material systems that were exposed for three years at locations on the North American Continent. The exposure locations are near the areas where Bell Model 206L Helicopters, that are in a NSA/U.S. Army sponsored flight service program, are flying in daily commercial service. The composite systems are: (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 Graphite/E-788 epoxy. All material systems exhibited good strength retention in compression and short beam shear. The Kevlar-49/LRF-277 epoxy retained 88 to 93 percent of the baseline strength while the other material systems exceeded 95 percent of baseline strength. Residual tensile strength of all materials did not show a significant reduction. The available moisture absorption data is also presented.

  20. Performance optimization of helicopter rotor blades

    NASA Technical Reports Server (NTRS)

    Walsh, Joanne L.

    1991-01-01

    As part of a center-wide activity at NASA Langley Research Center to develop multidisciplinary design procedures by accounting for discipline interactions, a performance design optimization procedure is developed. The procedure optimizes the aerodynamic performance of rotor blades by selecting the point of taper initiation, root chord, taper ratio, and maximum twist which minimize hover horsepower while not degrading forward flight performance. The procedure uses HOVT (a strip theory momentum analysis) to compute the horse power required for hover and the comprehensive helicopter analysis program CAMRAD to compute the horsepower required for forward flight and maneuver. The optimization algorithm consists of the general purpose optimization program CONMIN and approximate analyses. Sensitivity analyses consisting of derivatives of the objective function and constraints are carried out by forward finite differences. The procedure is applied to a test problem which is an analytical model of a wind tunnel model of a utility rotor blade.

  1. Helicopter flight simulation motion platform requirements

    NASA Astrophysics Data System (ADS)

    Schroeder, Jeffery Allyn

    Flight simulators attempt to reproduce in-flight pilot-vehicle behavior on the ground. This reproduction is challenging for helicopter simulators, as the pilot is often inextricably dependent on external cues for pilot-vehicle stabilization. One important simulator cue is platform motion; however, its required fidelity is unknown. To determine the required motion fidelity, several unique experiments were performed. A large displacement motion platform was used that allowed pilots to fly tasks with matched motion and visual cues. Then, the platform motion was modified to give cues varying from full motion to no motion. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositionings. This refutes the view that pilots estimate altitude and altitude rate in simulation solely from visual cues. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

  2. Results of NASA/Army transmission research

    NASA Technical Reports Server (NTRS)

    Coy, John J.; Townsend, Dennis P.; Coe, Harold H.

    1988-01-01

    Since 1970 the NASA Lewis Research Center and the U.S. Army Aviation Systems Command have shared an interest in advancing the technology for helicopter propulsion systems. In particular, that portion of the program that applies to the drive train and its various mechanical components are outlined. The major goals of the program were (and continue to be) to increase the life, reliability, and maintainability, reduce the weight, noise, and vibration, and maintain the relatively high mechanical efficiency of the gear train. Major historical milestones are reviewed, significant advances in technology for bearings, gears, and transmissions are discussed, and the outlook for the future is presented. The reference list is comprehensive.

  3. Correlation of rheological characteristics of lubricants with transmission efficiency measurements

    NASA Technical Reports Server (NTRS)

    Jacobson, B. O.; Hamrock, B. J.; Hoeglund, E.

    1985-01-01

    The power efficiency of a helicopter transmission has been analyzed for 11 lubricants by looking at the Newtonian and non-Newtonian properties of the lubricants. A non-Newtonian property of the lubricants was the limiting shear strength proportionality constant. The tests were performed on a high-pressure, short-time shear strength analyzer. A power efficiency formula that was obtained by analyzing the Newtonian and non-Newtonian properties of the lubricants is presented in detail.

  4. The environmental analysis of helicopter operations by Federal agencies: Current procedures and research needs

    NASA Technical Reports Server (NTRS)

    Smith, C. C.; Warner, D. B.; Dajani, J. S.

    1977-01-01

    The technical, economic, and environmental problems restricting commercial helicopter passenger operations are reviewed. The key considerations for effective assessment procedures are outlined and a preliminary model for the environmental analysis of helicopters is developed. It is recommended that this model, or some similar approach, be used as a common base for the development of comprehensive environmental assessment methods for each of the federal agencies concerned with helicopters. A description of the critical environmental research issues applicable to helicopters is also presented.

  5. The role of the helicopter in transportation. [technology assessment for use in civil aviation

    NASA Technical Reports Server (NTRS)

    Dajani, J. S.; Warner, D.; Epstein, D.; Obrien, J.

    1976-01-01

    A general overview is presented of the role that the helicopter plays in the current aviation scene with special emphasis on its use in the airport access function. Technological problems of present-day aircraft are discussed along with some plausible solutions. The economic and regulatory aspects of commercial helicopter operations are presented. Finally six commercial operations utilizing helicopters are reviewed and conditions that enhance the success of the helicopter in the airport access function are proposed.

  6. Amplifying the helicopter drift in a conformal HMD

    NASA Astrophysics Data System (ADS)

    Schmerwitz, Sven; Knabl, Patrizia M.; Lueken, Thomas; Doehler, Hans-Ullrich

    2016-05-01

    Helicopter operations require a well-controlled and minimal lateral drift shortly before ground contact. Any lateral speed exceeding this small threshold can cause a dangerous momentum around the roll axis, which may cause a total roll over of the helicopter. As long as pilots can observe visual cues from the ground, they are able to easily control the helicopter drift. But whenever natural vision is reduced or even obscured, e.g. due to night, fog, or dust, this controllability diminishes. Therefore helicopter operators could benefit from some type of "drift indication" that mitigates the influence of a degraded visual environment. Generally humans derive ego motion by the perceived environmental object flow. The visual cues perceived are located close to the helicopter, therefore even small movements can be recognized. This fact was used to investigate a modified drift indication. To enhance the perception of ego motion in a conformal HMD symbol set the measured movement was used to generate a pattern motion in the forward field of view close or on the landing pad. The paper will discuss the method of amplified ego motion drift indication. Aspects concerning impact factors like visualization type, location, gain and more will be addressed. Further conclusions from previous studies, a high fidelity experiment and a part task experiment, will be provided. A part task study will be presented that compared different amplified drift indications against a predictor. 24 participants, 15 holding a fixed wing license and 4 helicopter pilots, had to perform a dual task on a virtual reality headset. A simplified control model was used to steer a "helicopter" down to a landing pad while acknowledging randomly placed characters.

  7. Helicopter Parenting: The Effect of an Overbearing Caregiving Style on Peer Attachment and Self-Efficacy

    ERIC Educational Resources Information Center

    van Ingen, Daniel J.; Freiheit, Stacy R.; Steinfeldt, Jesse A.; Moore, Linda L.; Wimer, David J.; Knutt, Adelle D.; Scapinello, Samantha; Roberts, Amber

    2015-01-01

    Helicopter parenting, an observed phenomenon on college campuses, may adversely affect college students. The authors examined how helicopter parenting is related to self-efficacy and peer relationships among 190 undergraduate students ages 16 to 28 years. Helicopter parenting was associated with low self-efficacy, alienation from peers, and a lack…

  8. 46 CFR 109.575 - Accumulation of liquids on helicopter decks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Accumulation of liquids on helicopter decks. 109.575... DRILLING UNITS OPERATIONS Miscellaneous § 109.575 Accumulation of liquids on helicopter decks. The master or person in charge shall ensure that no liquids are allowed to accumulate on the helicopter decks....

  9. 46 CFR 109.575 - Accumulation of liquids on helicopter decks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Accumulation of liquids on helicopter decks. 109.575... DRILLING UNITS OPERATIONS Miscellaneous § 109.575 Accumulation of liquids on helicopter decks. The master or person in charge shall ensure that no liquids are allowed to accumulate on the helicopter decks....

  10. 46 CFR 109.575 - Accumulation of liquids on helicopter decks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Accumulation of liquids on helicopter decks. 109.575... DRILLING UNITS OPERATIONS Miscellaneous § 109.575 Accumulation of liquids on helicopter decks. The master or person in charge shall ensure that no liquids are allowed to accumulate on the helicopter decks....

  11. 46 CFR 109.575 - Accumulation of liquids on helicopter decks.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Accumulation of liquids on helicopter decks. 109.575... DRILLING UNITS OPERATIONS Miscellaneous § 109.575 Accumulation of liquids on helicopter decks. The master or person in charge shall ensure that no liquids are allowed to accumulate on the helicopter decks....

  12. 46 CFR 109.575 - Accumulation of liquids on helicopter decks.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Accumulation of liquids on helicopter decks. 109.575... DRILLING UNITS OPERATIONS Miscellaneous § 109.575 Accumulation of liquids on helicopter decks. The master or person in charge shall ensure that no liquids are allowed to accumulate on the helicopter decks....

  13. Effects of Head-Supported Devices on Female Aviators during Simulated Helicopter Missions

    DTIC Science & Technology

    1998-05-01

    addressed. 14. SUBJECT TERMS . , . . Helmets, Head-mounted displays, Head-supported devices, Night-vision goggles, Whole-body vibration , helicopter ...Training Phase 1" Simulated Helicopter Vibration 16 Subject Preparation 17 Maximum Voluntary Contraction and EMG Calibration 17 Sub-maximal Endurance 17...exposure of female military subjects to simulated helicopter vibration signatures and different helmet configurations. Ultimately, these limits must

  14. 78 FR 2223 - Airworthiness Directives; Eurocopter Deutschland GmbH Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-10

    ... cantilever assemblies, cyclic stick locking devices, or cyclic stick holder assemblies installed. This... cyclic stick on EC135 series helicopters, which may lead to loss of control of the helicopter. EASA also...-numbered Model MBB BK117 C-2 helicopters. These ASBs specify procedures to modify the cantilever...

  15. 14 CFR 135.271 - Helicopter hospital emergency medical evacuation service (HEMES).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....271 Helicopter hospital emergency medical evacuation service (HEMES). (a) No certificate holder may... assignment, for hospital emergency medical evacuation service helicopter operations unless that assignment... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Helicopter hospital emergency...

  16. 14 CFR 135.271 - Helicopter hospital emergency medical evacuation service (HEMES).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ....271 Helicopter hospital emergency medical evacuation service (HEMES). (a) No certificate holder may... assignment, for hospital emergency medical evacuation service helicopter operations unless that assignment... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Helicopter hospital emergency...

  17. 14 CFR 135.271 - Helicopter hospital emergency medical evacuation service (HEMES).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ....271 Helicopter hospital emergency medical evacuation service (HEMES). (a) No certificate holder may... assignment, for hospital emergency medical evacuation service helicopter operations unless that assignment... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Helicopter hospital emergency...

  18. 14 CFR 135.271 - Helicopter hospital emergency medical evacuation service (HEMES).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ....271 Helicopter hospital emergency medical evacuation service (HEMES). (a) No certificate holder may... assignment, for hospital emergency medical evacuation service helicopter operations unless that assignment... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Helicopter hospital emergency...

  19. 14 CFR 135.271 - Helicopter hospital emergency medical evacuation service (HEMES).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ....271 Helicopter hospital emergency medical evacuation service (HEMES). (a) No certificate holder may... assignment, for hospital emergency medical evacuation service helicopter operations unless that assignment... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Helicopter hospital emergency...

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    The effects of rotor downwash on helicopter fuselage aerodynamic characteristics were investigated. A rotor model for generating the downwash was mounted close to each of three fuselage models. The main report presents the force and moment data in both graphical and tabular form and the pressure data in graphical form. This supplement presents the pressure data in tabular form. Each run or parameter sweep is identified by a unique run number. The data points in each run are identified by a point number. The pressure data can be matched to the force data by matching the run and point number.

  1. W-band real-time passive millimeter-wave imager for helicopter collision avoidance

    NASA Astrophysics Data System (ADS)

    Salmon, Neil A.

    1999-07-01

    A w-band passive millimeter imager is proposed for use on a helicopter platform. The atmospheric transmission through fog and rain is much higher in the millimeter wave band than it is in the visible or infrared regions of the spectrum. This property enables passive millimeter wave imaging systems to offer recognizable imagery in adverse weather conditions. Furthermore, as the technique is based on incoherent imaging, it can be used in environments where it may be difficult for radar to process data into recognizable imagery. The 30 cm diameter real-time passive millimeter wave imager described here will have a radiometric sensitivity of around 1 degree(s)C and a radiation bandwidth of 80 GHz to 105 GHz. The system is based on the DERA mechanical scanning passive millimeter wave imager architecture.

  2. Terfenol-D driven flaps for helicopter vibration reduction

    NASA Astrophysics Data System (ADS)

    Fenn, Ralph C.; Downer, James R.; Bushko, Dariusz A.; Gondhalekar, Vijay; Ham, Norman D.

    1996-02-01

    The utility of helicopter aviation is limited by the high vibration levels caused by the interaction of each rotor blade with the wake of preceding blades. Existing full-blade actuation using a swashplate has various problems such as insufficient bandwidth, limitations in the number of harmonics controlled, high maintenance, and lack of spanwise lift variation. These problems are avoided by the proposed flap operated, individual blade control system, which uses magnetostrictive actuation technology. Terfenol-D actuation has many advantages over competing technologies such as hydraulic systems, electric motors, and piezoelectric elements. These benefits include all-electric operation, simplicity and reliability, low mass, low voltage, and insensitivity to centripetal acceleration. A blade mounted Terfenol-D actuator was developed for the high-weight-penalty helicopter application. The optimum coil to Terfenol-D volume ratio was derived that gives the highest mechanical power output for a small actuator envelope and mass. A fixed ability to dissipate coil resistive losses is assumed. The magnetostrictive actuation system will weigh less than 1% of gross vehicle weight, and use only 0.7% of cruise power. Other required subsystems of the vibration reduction system are available from commercial sources or are described in the literature. Helicopter vibration reduction greater than 90% is predicted because of superior actuator performance and individual blade control. This magnetostrictive actuator technology will also produce future helicopter systems having lower noise and higher performance. Such advances will significantly improve the utility and competitiveness of helicopters for civilian and military transportation.

  3. Laboratory studies of scales for measuring helicopter noise

    NASA Technical Reports Server (NTRS)

    Ollerhead, J. B.

    1982-01-01

    The adequacy of the effective perceived noise level (EPNL) procedure for rating helicopter noise annoyance was investigated. Recordings of 89 helicopters and 30 fixed wing aircraft (CTOL) flyover sounds were rated with respect to annoyance by groups of approximately 40 subjects. The average annoyance scores were transformed to annoyance levels defined as the equally annoying sound levels of a fixed reference sound. The sound levels of the test sounds were measured on various scales, with and without corrections for duration, tones, and impulsiveness. On average, the helicopter sounds were judged equally annoying to CTOL sounds when their duration corrected levels are approximately 2 dB higher. Multiple regression analysis indicated that, provided the helicopter/CTOL difference of about 2 dB is taken into account, the particular linear combination of level, duration, and tone corrections inherent in EPNL is close to optimum. The results reveal no general requirement for special EPNL correction terms to penalize helicopter sounds which are particularly impulsive; impulsiveness causes spectral and temporal changes which themselves adequately amplify conventionally measured sound levels.

  4. Helicopter tail rotor blade-vortex interaction noise

    NASA Technical Reports Server (NTRS)

    George, Albert R.; Chou, S.-T.

    1987-01-01

    A study is made of helicopter tail rotor noise, particularly that due to the interactions with main rotor tip vortices. Summarized here are present analysis, the computer codes, and the results of several test cases. Amiet's unsteady thin airfoil theory is used to calculate the acoustics of blade-vortex interaction. The noise source is modelled as a force dipole resulting from an airfoil of infinite span chopping through a skewed line vortex. To analyze the interactions between helicopter tail rotor and main rotor tip vortices, we developed a two-step approach: (1) the main rotor tip vortex system is obtained through a free wake geometry calculation of the main rotor using CAMRAD code; (2) acoustic analysis takes the results from the aerodynamic interaction analysis and calculates the farfield pressure signatures for the interactions. It is found that under a wide range of helicopter flight conditions, acoustic pressure fluctuations of significant magnitude can be generated by tail rotors due to a series of interactions with main rotor tip vortices. This noise mechanism depends strongly on the helicopter flight conditions and the relative location and phasing of the main and tail rotors. fluctuations of significant magnitude can be generated by tail rotors due to a series of interactions with main rotor tip vortices. This noise mechanism depends strongly upon the helicopter flight conditions and the relative location and phasing of the main and tail rotors.

  5. A Newly Adopted Helicopter Platform for Geophysical and Remote Sensing

    NASA Astrophysics Data System (ADS)

    Meyer, Uwe

    2014-05-01

    The Federal Institute for Geosciences and Natural Resources in Hannover owns a Sikorsky S-76B helicopter for geophysical and remote sensing airborne surveys. This platform has been completely refurbished and in parts newly designed to be fit for easy installations of complex geophysical instruments underneath, upon and within the helicopter. The airborne platform is equipped with a modern basic navigation equipment consisting of several GNSS antennae, state of the art inertial navigation systems, laser altimeter and video camera systems. Different other modules can be added to the helicopter as a state of the art gamma spectrometer, a laser scanner, airborne gravity meters etc. within the cabin. Moreover, external sensing systems as a photogrammetric camera, infraread camera or optional mulitspectral systems can be installed on the outer skin of the cabin. Different kinds of bird systems towed underneath the helicopter can be hooked up using standard cabling, glas fibres or wireless LAN. Available birds are equipped for frequency domain electromagnetics or gradient magnetics (IPHT Jena & Supracon, Jena). Besides, large georadar systems can be installed as well. The helicopter is able as well to carry TEM-gear or system in development. Main survey targets are groundwater systems, mineral deposits and natural hazards.

  6. Evaluation of Standard Gear Metrics in Helicopter Flight Operation

    NASA Technical Reports Server (NTRS)

    Mosher, M.; Pryor, A. H.; Huff, E. M.

    2002-01-01

    sense that the rpm, torque and forces on the gear have been held steady. For gears used in a dynamic environment such as that occurring in aircraft, the rpm, torque and forces on the gear are constantly changing. The authors have measured significant variation in rpm and torque in the transmissions of helicopters in controlled steady flight conditions flown by highly proficient test pilots. Statistical analyses of the data taken in flight show significant nonstationarity in the vibration measurements. These deviations from stationarity may increase false alarms in gear monitoring during aircraft flight. In the proposed paper, the authors will study vibration measurements made in flight on an AH- 1 Cobra and an OH-58C Kiowa helicopters. The primary focus will be the development of a methodology to assess the impact of nonstationarity on false alarms. Issues to be addressed include how time synchronous averages are constructed from raw data as well as how lack of stationarity effects the behavior of single value metrics. Emphasis will be placed on the occurrence of false alarms with the use of standard metrics. In order to maintain an acceptable level of false alarms in the flight environment, this study will also address the determination of appropriate threshold levels, which may need to be higher than for test rigs.

  7. Split torque transmission load sharing

    NASA Technical Reports Server (NTRS)

    Krantz, T. L.; Rashidi, M.; Kish, J. G.

    1992-01-01

    Split torque transmissions are attractive alternatives to conventional planetary designs for helicopter transmissions. The split torque designs can offer lighter weight and fewer parts but have not been used extensively for lack of experience, especially with obtaining proper load sharing. Two split torque designs that use different load sharing methods have been studied. Precise indexing and alignment of the geartrain to produce acceptable load sharing has been demonstrated. An elastomeric torque splitter that has large torsional compliance and damping produces even better load sharing while reducing dynamic transmission error and noise. However, the elastomeric torque splitter as now configured is not capable over the full range of operating conditions of a fielded system. A thrust balancing load sharing device was evaluated. Friction forces that oppose the motion of the balance mechanism are significant. A static analysis suggests increasing the helix angle of the input pinion of the thrust balancing design. Also, dynamic analysis of this design predicts good load sharing and significant torsional response to accumulative pitch errors of the gears.

  8. Semi-active control of helicopter vibration using controllable stiffness and damping devices

    NASA Astrophysics Data System (ADS)

    Anusonti-Inthra, Phuriwat

    Semi-active concepts for helicopter vibration reduction are developed and evaluated in this dissertation. Semi-active devices, controllable stiffness devices or controllable orifice dampers, are introduced; (i) in the blade root region (rotor-based concept) and (ii) between the rotor and the fuselage as semi-active isolators (in the non-rotating frame). Corresponding semi-active controllers for helicopter vibration reduction are also developed. The effectiveness of the rotor-based semi-active vibration reduction concept (using stiffness and damping variation) is demonstrated for a 4-bladed hingeless rotor helicopter in moderate- to high-speed forward flight. A sensitivity study shows that the stiffness variation of root element can reduce hub vibrations when proper amplitude and phase are used. Furthermore, the optimal semi-active control scheme can determine the combination of stiffness variations that produce significant vibration reduction in all components of vibratory hub loads simultaneously. It is demonstrated that desired cyclic variations in properties of the blade root region can be practically achieved using discrete controllable stiffness devices and controllable dampers, especially in the flap and lag directions. These discrete controllable devices can produce 35--50% reduction in a composite vibration index representing all components of vibratory hub loads. No detrimental increases are observed in the lower harmonics of blade loads and blade response (which contribute to the dynamic stresses) and controllable device internal loads, when the optimal stiffness and damping variations are introduced. The effectiveness of optimal stiffness and damping variations in reducing hub vibration is retained over a range of cruise speeds and for variations in fundamental rotor properties. The effectiveness of the semi-active isolator is demonstrated for a simplified single degree of freedom system representing the semi-active isolation system. The rotor

  9. Passive suppression of helicopter ground resonance using nonlinear energy sinks attached on the helicopter blades

    NASA Astrophysics Data System (ADS)

    Bergeot, B.; Bellizzi, S.; Cochelin, B.

    2017-03-01

    This paper investigates the passive control of a rotor instability named helicopter Ground Resonance (GR). The passive device consists of a set of essential cubic nonlinear absorbers named Nonlinear Energy Sinks (NES) each of them positioned on a blade. A dynamic model reproducing helicopter GR instability is presented and transformed to a time-invariant nonlinear system using a multi-blade coordinate transformation based on Fourier transform mapping the dynamic state variables into a non-rotating reference frame. Combining complexification, slow/fast partition of the dynamics and averaging procedure, a reduced model is obtained which allowed us to use the so-called geometric singular perturbation analysis to characterize the steady state response regimes. As in the case of a NES attached to the fuselage, it is shown that under suitable conditions, GR instability can be completely suppressed, partially suppressed through periodic response or strongly modulated response. Relevant analytical results are compared, for validation purposes, to direct integration of the reference and reduced models.

  10. Study of operational parameters impacting helicopter fuel consumption. [using computer techniques (computer programs)

    NASA Technical Reports Server (NTRS)

    Cross, J. L.; Stevens, D. D.

    1976-01-01

    A computerized study of operational parameters affecting helicopter fuel consumption was conducted as an integral part of the NASA Civil Helicopter Technology Program. The study utilized the Helicopter Sizing and Performance Computer Program (HESCOMP) developed by the Boeing-Vertol Company and NASA Ames Research Center. An introduction to HESCOMP is incorporated in this report. The results presented were calculated using the NASA CH-53 civil helicopter research aircraft specifications. Plots from which optimum flight conditions for minimum fuel use that can be obtained are presented for this aircraft. The results of the study are considered to be generally indicative of trends for all helicopters.

  11. Visual and motion cueing in helicopter simulation

    NASA Technical Reports Server (NTRS)

    Bray, R. S.

    1985-01-01

    Early experience in fixed-cockpit simulators, with limited field of view, demonstrated the basic difficulties of simulating helicopter flight at the level of subjective fidelity required for confident evaluation of vehicle characteristics. More recent programs, utilizing large-amplitude cockpit motion and a multiwindow visual-simulation system have received a much higher degree of pilot acceptance. However, none of these simulations has presented critical visual-flight tasks that have been accepted by the pilots as the full equivalent of flight. In this paper, the visual cues presented in the simulator are compared with those of flight in an attempt to identify deficiencies that contribute significantly to these assessments. For the low-amplitude maneuvering tasks normally associated with the hover mode, the unique motion capabilities of the Vertical Motion Simulator (VMS) at Ames Research Center permit nearly a full representation of vehicle motion. Especially appreciated in these tasks are the vertical-acceleration responses to collective control. For larger-amplitude maneuvering, motion fidelity must suffer diminution through direct attenuation through high-pass filtering washout of the computer cockpit accelerations or both. Experiments were conducted in an attempt to determine the effects of these distortions on pilot performance of height-control tasks.

  12. Condition Monitoring for Helicopter Data. Appendix A

    NASA Technical Reports Server (NTRS)

    Wen, Fang; Willett, Peter; Deb, Somnath

    2000-01-01

    In this paper the classical "Westland" set of empirical accelerometer helicopter data is analyzed with the aim of condition monitoring for diagnostic purposes. The goal is to determine features for failure events from these data, via a proprietary signal processing toolbox, and to weigh these according to a variety of classification algorithms. As regards signal processing, it appears that the autoregressive (AR) coefficients from a simple linear model encapsulate a great deal of information in a relatively few measurements; it has also been found that augmentation of these by harmonic and other parameters can improve classification significantly. As regards classification, several techniques have been explored, among these restricted Coulomb energy (RCE) networks, learning vector quantization (LVQ), Gaussian mixture classifiers and decision trees. A problem with these approaches, and in common with many classification paradigms, is that augmentation of the feature dimension can degrade classification ability. Thus, we also introduce the Bayesian data reduction algorithm (BDRA), which imposes a Dirichlet prior on training data and is thus able to quantify probability of error in an exact manner, such that features may be discarded or coarsened appropriately.

  13. Modeling Aerodynamically Generated Sound of Helicopter Rotors

    NASA Technical Reports Server (NTRS)

    Brentner, Kenneth S.; Farassat, F.

    2002-01-01

    A great deal of progress has been made in the modeling of aerodynamically generated sound of rotors over the past decade. Although the modeling effort has focused on helicopter main rotors, the theory is generally valid for a wide range of rotor configurations. The Ffowcs Williams Hawkings (FW-H) equation has been the foundation for much of the development. The monopole and dipole source terms of the FW-H equation account for the thickness and loading noise, respectively. Bladevortex-interaction noise and broadband noise are important types of loading noise, hence much research has been directed toward the accurate modeling of these noise mechanisms. Both subsonic and supersonic quadrupole noise formulations have been developed for the prediction of high-speed impulsive noise. In an effort to eliminate the need to compute the quadrupole contribution, the FW-H equation has also been utilized on permeable surfaces surrounding all physical noise sources. Comparisons of the Kirchhoff formulation for moving surfaces with the FW-H equation have shown that the Kirchhoff formulation for moving surfaces can give erroneous results for aeroacoustic problems. Finally, significant progress has been made incorporating the rotor noise models into full vehicle noise prediction tools.

  14. Helicopter Flight Simulation Motion Platform Requirements

    NASA Technical Reports Server (NTRS)

    Schroeder, Jeffery Allyn

    1999-01-01

    To determine motion fidelity requirements, a series of piloted simulations was performed. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositioning. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

  15. Helicopter hub fairing and pylon interference drag

    NASA Technical Reports Server (NTRS)

    Graham, D. R.; Sung, D. Y.; Young, L. A.; Louie, A. W.; Stroub, R. H.

    1989-01-01

    A wind tunnel test was conducted to study the aerodynamics of helicopter hub and pylon fairings. The test was conducted in the 7-by 10 Foot Subsonic Wind Tunnel (Number 2) at Ames Research Center using a 1/5-scale XH-59A fuselage model. The primary focus of the test was on the rotor hub fairing and pylon mutual interference drag. Parametric studies of pylon and hub fairing geometry were also conducted. This report presents the major findings of the test as well as tabulated force and moment data, flow visualization photographs, and graphical presentations of the drag data. The test results indicate that substantial drag reduction can be attained through the use of a cambered hub fairing with circular arc upper surface and flat lower surface. Furthermore, a considerable portion of the overall drag reduction is attributed to the reduction in the hub-on-pylon interference drag. It is also observed that the lower surface curvature of the fairing has a strong influence on the hub fairing and on pylon interference drag. However, the drag reduction benefit that was obtained by using the cambered hub fairing with a flat lower surface was adversely affected by the clearance between the hub fairing and the pylon.

  16. Yaw Motion Cues in Helicopter Simulation

    NASA Technical Reports Server (NTRS)

    Schroeder, Jeffrey A.; Johnson, Walter W.

    1996-01-01

    A piloted simulation that examined the effects of yaw motion cues on pilot-vehicle performance, pilot workload, and pilot motion perception was conducted on the NASA Ames Vertical Motion Simulator. The vehicle model that was used represented an AH-64 helicopter. Three tasks were performed in which only combinations of vehicle yaw and vertical displacement were allowed. The commands issued to the motion platform were modified to present the following four motion configurations for a pilot located forward of the center of rotation: (1) only the linear translations, (2) only the angular rotation, (3) both the linear translations and the angular rotation, and (4) no motion. The objective data indicated that pilot-vehicle performance was reduced and the necessary control activity increased when linear motion was removed; however, the lack of angular rotation did not result in a measured degradation for almost all cases. Also, pilots provided subjective assessments of their compensation required, the motion fidelity, and their judgment of whether or not linear or rotational cockpit motion was present. Ratings of compensation and fidelity were affected only by linear acceleration, and the rotational motion had no significant impact. Also, when only linear motion was present, pilots typically reported the presence of rotation. Thus, linear acceleration cues, not yaw rotational cues, appear necessary to simulate hovering flight.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  18. Helicopter-V/STOL dynamic wind and turbulence design methodology

    NASA Technical Reports Server (NTRS)

    Bailey, J. Earl

    1987-01-01

    Aircraft and helicopter accidents due to severe dynamic wind and turbulence continue to present challenging design problems. The development of the current set of design analysis tools for a aircraft wind and turbulence design began in the 1940's and 1950's. The areas of helicopter dynamic wind and turbulence modeling and vehicle response to severe dynamic wind inputs (microburst type phenomena) during takeoff and landing remain as major unsolved design problems from a lack of both environmental data and computational methodology. The development of helicopter and V/STOL dynamic wind and turbulence response computation methology is reviewed, the current state of the design art in industry is outlined, and comments on design methodology are made which may serve to improve future flight vehicle design.

  19. A mathematical model of the UH-60 helicopter

    NASA Technical Reports Server (NTRS)

    Hilbert, K. B.

    1984-01-01

    This report documents the revisions made to a ten-degree-of-freedom, full-flight envelope, generic helicopter mathematical model to represent the UH-60 helicopter accurately. The major modifications to the model include fuselage aerodynamic force and moment equations specific to the UH-60, a canted tail rotor, a horizontal stabilator with variable incidence, and a pitch bias actuator (PBA). In addition, this report presents a full set of parameters and numerical values which describe the helicopter configuration and physical characteristics. Model validation was accomplished by comparison of trim and stability derivative data generated from the UH-60 math model with data generated from a similar total force and moment math model.

  20. Flap motion of helicopter rotors with novel, dynamic stall model

    NASA Astrophysics Data System (ADS)

    Han, Wei; Liu, Jie; Liu, Chun; Chen, Lei; Su, Xichao; Zhao, Peng

    2016-01-01

    In this paper, a nonlinear flapping equation for large inflow angles and flap angles is established by analyzing the aerodynamics of helicopter blade elements. In order to obtain a generalized flap equation, the Snel stall model was first applied to determine the lift coefficient of the helicopter rotor. A simulation experiment for specific airfoils was then conducted to verify the effectiveness of the Snel stall model as it applies to helicopters. Results show that the model requires no extraneous parameters compared to the traditional stall model and is highly accurate and practically applicable. Based on the model, the relationship between the flapping angle and the angle of attack was analyzed, as well as the advance ratio under the dynamic stall state.

  1. Evaluation of ride quality prediction methods for operational military helicopters

    NASA Technical Reports Server (NTRS)

    Leatherwood, J. D.; Clevenson, S. A.; Hollenbaugh, D. D.

    1984-01-01

    The results of a simulator study conducted to compare and validate various ride quality prediction methods for use in assessing passenger/crew ride comfort within helicopters are presented. Included are results quantifying 35 helicopter pilots' discomfort responses to helicopter interior noise and vibration typical of routine flights, assessment of various ride quality metrics including the NASA ride comfort model, and examination of possible criteria approaches. Results of the study indicated that crew discomfort results from a complex interaction between vibration and interior noise. Overall measures such as weighted or unweighted root-mean-square acceleration level and A-weighted noise level were not good predictors of discomfort. Accurate prediction required a metric incorporating the interactive effects of both noise and vibration. The best metric for predicting crew comfort to the combined noise and vibration environment was the NASA discomfort index.

  2. Airflow Hazard Visualization for Helicopter Pilots: Flight Simulation Study Results

    NASA Technical Reports Server (NTRS)

    Aragon, Cecilia R.; Long, Kurtis R.

    2005-01-01

    Airflow hazards such as vortices or low level wind shear have been identified as a primary contributing factor in many helicopter accidents. US Navy ships generate airwakes over their decks, creating potentially hazardous conditions for shipboard rotorcraft launch and recovery. Recent sensor developments may enable the delivery of airwake data to the cockpit, where visualizing the hazard data may improve safety and possibly extend ship/helicopter operational envelopes. A prototype flight-deck airflow hazard visualization system was implemented on a high-fidelity rotorcraft flight dynamics simulator. Experienced helicopter pilots, including pilots from all five branches of the military, participated in a usability study of the system. Data was collected both objectively from the simulator and subjectively from post-test questionnaires. Results of the data analysis are presented, demonstrating a reduction in crash rate and other trends that illustrate the potential of airflow hazard visualization to improve flight safety.

  3. Digital resolver for helicopter model blade motion analysis

    NASA Technical Reports Server (NTRS)

    Daniels, T. S.; Berry, J. D.; Park, S.

    1992-01-01

    The paper reports the development and initial testing of a digital resolver to replace existing analog signal processing instrumentation. Radiometers, mounted directly on one of the fully articulated blades, are electrically connected through a slip ring to analog signal processing circuitry. The measured signals are periodic with azimuth angle and are resolved into harmonic components, with 0 deg over the tail. The periodic nature of the helicopter blade motion restricts the frequency content of each flapping and yaw signal to the fundamental and harmonics of the rotor rotational frequency. A minicomputer is employed to collect these data and then plot them graphically in real time. With this and other information generated by the instrumentation, a helicopter test pilot can then adjust the helicopter model's controls to achieve the desired aerodynamic test conditions.

  4. Vision-based range estimation using helicopter flight data

    NASA Technical Reports Server (NTRS)

    Smith, Phillip N.; Sridhar, Banavar; Hussien, Bassam

    1992-01-01

    Pilot aiding during low-altitude flight depends on the ability to detect and locate obstacles near the helicopter's intended flightpath. Computer-vision-based methods provide one general approach for obstacle detection and range estimation. Several algorithms have been developed for this purpose, but have not been tested with actual flight data. This paper presents results obtained using helicopter flight data with a feature-based range estimation algorithm. A method for recursively estimating range using a Kalman filter with a monocular sequence of images and knowledge of the camera's motion is described. The helicopter flight experiment and four resulting datasets are discussed. Finally the performance of the range estimation algorithm is explored in detail based on comparison of the range estimates with true range measurements collected during the flight experiment.

  5. Vision-based range estimation using helicopter flight data

    NASA Technical Reports Server (NTRS)

    Smith, Phillip N.; Sridhar, Banavar; Hussein, Bassam

    1992-01-01

    Pilot aiding during low-altitude flight depends on the ability to detect and locate obstacles near the helicopter's intended flightpath. Computer-vision-based methods provide one general approach for obstacle detection and range estimation. Several algorithms have been developed for this purpose, but have not been tested with actual flight data. This paper presents results obtained using helicopter flight data with a feature-based range estimation algorithm. A method for recursively estimating range using a Kalman filter with a monocular sequence of images and knowledge of the camera's motion is described. The helicopter flight experiment and one of four resulting datasets is briefly discussed. Finally the performance of the range estimation algorithm is explored based on comparison of the range estimates with true range measurements collected during the flight experiment.

  6. Cognitive perspectives on map displays for helicopter flight

    NASA Technical Reports Server (NTRS)

    Harwood, Kelly

    1989-01-01

    Currently accessible technologies are providing entirely new display concepts for enhancing helicopter navigation. Yet the effectiveness of such displays depends on the extent to which they are configured according to principles from research on human performance. Computer generated map displays in the present study were configured according to previous research on maps, navigational problem solving, and spatial cognition in large scale environments. Interest centered on the representation of different spatial relationships that would best support helicopter navigational problem solving. One map display emphasized the global relationships between objects in the environment. The other map showed the pilot's relationship to objects as he traveled through the environment. Twenty skilled pilots used the maps to complete several navigational tasks that occurred within a realistic simulation program tailored for helicopter navigation. Findings indicate that the type of task and mode of flight (low level or Nap of the Earth (NOE)) are important determinants of map display effectiveness.

  7. Noise measurement flight test of five light helicopters

    NASA Astrophysics Data System (ADS)

    Rickley, Edward J.; Jones, Kenneth E.; Keller, Amanda S.; Fleming, Gregg G.

    1993-07-01

    The U.S. Department of Transportation, Federal Aviation Administration, (U.S.DOT/FAA), along with the U.S.DOT, Research and Special Programs Administration, Volpe National Transportation Systems Center (RSPA/Volpe Center) conducted a helicopter noise measurement flight test in Champaign, Illinois, during the period 22-26 July 1991. The primary objective of the study was to obtain the field data necessary to examine the feasibility of a simplified helicopter-noise-certification procedure (screening test). Acoustic data were measured by and stored on a hand-held sound-level meter (on-line processing) and recorded on digital tape for later off-line processing. A comparison of the measured on-line acoustic data with the acoustic data processed off-line provided the foundation necessary to evaluate the feasibility of the proposed screening test. In addition to acoustic measurements, meteorological data and helicopter tracking and performance data were also obtained.

  8. Prediction of helicopter rotor noise from measured blade surface pressure

    NASA Astrophysics Data System (ADS)

    Succi, G. P.; Brieger, J. T.

    The current techniques of helicopter rotor noise prediction attempt to describe the details of the noise field precisely and remove the empiricisms and restrictions inherent in previous methods. These techniques require detailed inputs of the rotor geometry, operating conditions, and blade surface pressure distribution. The purpose of this paper is to review those techniques in general and the Farassat/Nystrom analysis in particular. The predictions of the Farassat/Nystrom noise computer program, using both measured and calculated blade surface pressure data, are compared to measured noise level data. This study is based on a contract from NASA to Bolt Beranek and Newman Inc. (BBN) with measured data from the AH-lG Helicopter Operational Loads Survey flight test program supplied by Bell Helicopter Textron.

  9. Medical helicopters in wilderness search and rescue operations.

    PubMed

    Grissom, Colin K; Thomas, Frank; James, Brett

    2006-01-01

    Medical helicopters may be asked to assist in wilderness search and rescue (SAR) operations to quickly reach patients in remote areas and provide medical care and transport of sick or injured persons. The number 1 priority for any medical helicopter involved in an SAR operation is safety, which is considered at each decision point. The involvement of a medical helicopter service begins with a request from a local agency for support. Obtaining key information about the SAR operation from the local agency is essential for deciding whether to accept the mission and for making appropriate preparations for the mission. While en route to the SAR location, the medical crew can review the information regarding location and patient status. Once on location, the crew can survey the scene from the air before landing at the command post to brief with SAR personnel regarding the mission. An initial survey of the scene from the air is important for identifying landing zones and evaluating the terrain where the rescue will occur. A face-to-face briefing with SAR personnel is preferable to learn specifically what type of mission is requested. The medical helicopter crew is empowered to decline the mission for safety reasons at any step. The actual rescue may be done by inserting the helicopter at the scene in nontechnical terrain or by having SAR personnel extricate the patient and deliver him or her to the medical helicopter crew at the nearest safe landing zone. Medical care and transport of the patient as indicated by injuries or illness then occurs. Finally, a postmission debriefing is essential for identifying problems that occurred during the mission and implementing corrections for improvement.

  10. Dynamic wake distortion model for helicopter maneuvering flight

    NASA Astrophysics Data System (ADS)

    Zhao, Jinggen

    A new rotor dynamic wake distortion model, which can be used to account for the rotor transient wake distortion effect on inflow across the rotor disk during helicopter maneuvering and transitional flight in both hover and forward flight conditions, is developed. The dynamic growths of the induced inflow perturbation across rotor disk during different transient maneuvers, such as a step pitch or roll rate, a step climb rate and a step change of advance ratio are investigated by using a dynamic vortex tube analysis. Based on the vortex tube results, a rotor dynamic wake distortion model, which is expressed in terms of a set of ordinary differential equations, with rotor longitudinal and lateral wake curvatures, wake skew and wake spacing as states, is developed. Also, both the Pitt-Peters dynamic inflow model and the Peters-He finite state inflow model for axial or forward flight are augmented to account for rotor dynamic wake distortion effect during helicopter maneuvering flight. To model the aerodynamic interaction among main rotor, tail rotor and empennage caused by rotor wake curvature effect during helicopter maneuvering flight, a reduced order model based on a vortex tube analysis is developed. Both the augmented Pitt-Peters dynamic inflow model and the augmented Peters-He finite state inflow model, combined with the developed dynamic wake distortion model, together with the interaction model are implemented in a generic helicopter simulation program of UH-60 Black Hawk helicopter and the simulated vehicle control responses in both time domain and frequency domain are compared with flight test data of a UH-60 Black Hawk helicopter in both hover and low speed forward flight conditions.

  11. Computer vision sensor for autonomous helicopter hover stabilization

    NASA Astrophysics Data System (ADS)

    Oertel, Carl-Henrik

    1997-06-01

    Sensors for synthetic vision are needed to extend the mission profiles of helicopters. A special task for various applications is the autonomous position hold of a helicopter above a ground fixed or moving target. A computer-vision based system, which is able to observe the helicopter flight state during hover and low speed, based on the detection and tracking of significant but arbitrary features, has been developed by the Institute of Flight Mechanics of DLR Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. The approach is as follows: A CCD camera looks straight downward to the ground and produces an image of the ground view. The digitized video signal is fed into a high performance on- board computer which looks for distinctive features in the image. Any motion of the helicopter results in movements of these patterns in the camera image. By tracking the distinctive features during the succession of incoming images and by the support of inertial sensor data, it is possible to calculate all necessary helicopter state variables, which are needed for a position hold control algorithm. This information is gained from a state variable observer. That means that no additional information about the appearance of the camera view has to be known in advance to achieve autonomous helicopter hover stabilization. The hardware architecture for this image evaluation system mainly consists of several PowerPC processors which communicate with the aid of transputers and an image distribution bus. Feature tracking is performed by a dedicated 2D-correlator subsystem. The paper presents the characteristics of the computer vision sensor and demonstrates its functionality.

  12. Conceptual Design and Performance Analysis for a Large Civil Compound Helicopter

    NASA Technical Reports Server (NTRS)

    Russell, Carl; Johnson, Wayne

    2012-01-01

    A conceptual design study of a large civil compound helicopter is presented. The objective is to determine how a compound helicopter performs when compared to both a conventional helicopter and a tiltrotor using a design mission that is shorter than optimal for a tiltrotor and longer than optimal for a helicopter. The designs are generated and analyzed using conceptual design software and are further evaluated with a comprehensive rotorcraft analysis code. Multiple metrics are used to determine the suitability of each design for the given mission. Plots of various trade studies and parameter sweeps as well as comprehensive analysis results are presented. The results suggest that the compound helicopter examined for this study would not be competitive with a tiltrotor or conventional helicopter, but multiple possibilities are identified for improving the performance of the compound helicopter in future research.

  13. Summary highlights of the Advanced Rotorcraft Transmission (ART) program

    NASA Technical Reports Server (NTRS)

    Bill, Robert C.

    1992-01-01

    The NASA/U.S. Army Advanced Rotorcraft Transmission (ART) program is charged with the development and demonstration of lightweight, durable drivetrains for next-generation rotorcraft: (1) a Future Air Attack Vehicle for tactical ground-support and air-to-air missions, and (2) an Advanced Cargo Aircraft for heavy-lift field-support operations. Both tilt-rotor and more conventional helicopter configurations have been studied by the ART program. ART performance goals are sought through the use of advanced component materials and lubrication systems, transmission and geartrain configurations, and airframe/drivetrain integrations.

  14. Calculated Hovering Helicopter Flight Dynamics with a Circulation Controlled Rotor

    NASA Technical Reports Server (NTRS)

    Johnson, W.; Chopra, I.

    1977-01-01

    The influence of the rotor blowing coefficient on the calculated roots of the longitudinal and lateral motion was examined for a range of values of the rotor lift and the blade flap frequency. The control characteristics of a helicopter with a circulation controlled rotor are discussed. The principal effect of the blowing is a reduction in the rotor speed stability derivative. Above a critical level of blowing coefficient, which depends on the flap frequency and rotor lift, negative speed stability is produced and the dynamic characteristics of the helicopter are radically altered.

  15. Research requirements for the reduction of helicopter vibration

    NASA Technical Reports Server (NTRS)

    Doman, G. S.

    1976-01-01

    All prospective approaches to the reduction of helicopter vibrations were searched to establish insight for the planning of a corrective research program. The state of the art as revealed in the literature is summed up and followed by a discussion of state-of-the-art solutions and of identified technological gaps. It is applicable to all helicopters without regard to size. Extending the historic trend toward lower vibration levels will require the successful application of principles which isolate the fuselage from the rotor systems. Simplicity of the necessary isolation systems should be facilitated by providing other refinements of the dynamic design of the system.

  16. Rotary-wing aerodynamics. Volume 2: Performance prediction of helicopters

    NASA Technical Reports Server (NTRS)

    Keys, C. N.; Stephniewski, W. Z. (Editor)

    1979-01-01

    Application of theories, as well as, special methods of procedures applicable to performance prediction are illustrated first, on an example of the conventional helicopter and then, winged and tandem configurations. Performance prediction of conventional helicopters in hover and vertical ascent are investigated. Various approaches to performance prediction in forward translation are presented. Performance problems are discussed only this time, a wing is added to the baseline configuration, and both aircraft are compared with respect to their performance. This comparison is extended to a tandem. Appendices on methods for estimating performance guarantees and growth of aircraft concludes this volume.

  17. Preliminary Analysis of Helicopter Options to Support Tunisian Counterterrorism Operations

    DTIC Science & Technology

    2016-04-27

    cohesion. • The mission task is movement of the entire assault element to the landing zone in a single mission, or “turn.” Transit is at medium altitude...manufactured by Airbus Helicopters) also has the potential to be a more cost- effective platform. Helicopter platforms shown in green are at least 15...research, the CH-47D was found to be more cost-effective than the Mi-17v5. In that analysis, company-sized movements ranged from 90 to 160 personnel (PAX

  18. Important Scaling Parameters for Testing Model-Scale Helicopter Rotors

    NASA Technical Reports Server (NTRS)

    Singleton, Jeffrey D.; Yeager, William T., Jr.

    1998-01-01

    An investigation into the effects of aerodynamic and aeroelastic scaling parameters on model scale helicopter rotors has been conducted in the NASA Langley Transonic Dynamics Tunnel. The effect of varying Reynolds number, blade Lock number, and structural elasticity on rotor performance has been studied and the performance results are discussed herein for two different rotor blade sets at two rotor advance ratios. One set of rotor blades were rigid and the other set of blades were dynamically scaled to be representative of a main rotor design for a utility class helicopter. The investigation was con-densities permits the acquisition of data for several Reynolds and Lock number combinations.

  19. Engineering Design Handbook. Helicopter Engineering. Part One. Preliminary Design

    DTIC Science & Technology

    1974-08-30

    sec 3. C. M. Harris and C. E. Crede, FRds., Shock and w= reference frequency, rad/sec Vibration Handbook Volume II, Section 28, w, structural blade...American Helicopter Society 12 (January 1947). (October 1967). 9. R. G. Ricks, A Study of Tandem Helicopter 22. C. M. Harris and C. E. Crede, Eds.. (Ref. 3...limits of 0.90, what would this mean in practical poter programs with random input, that are run suffi- terms? It would mean that. if’an infinitely

  20. Impact of helicopters on trauma care and clinical results.

    PubMed Central

    Moylan, J A

    1988-01-01

    This report reviews the history of the development of civilian helicopter ambulance program as a component of a total emergency medical services (EMS) system. Current literature demonstrates significant reduction in trauma mortality for those patients transported by air either from the scene of the accident or from an outlying hospital to a trauma center. The primary factor is not the speed of the transport but administration of life-saving care by the helicopter medical crew at the scene of the accident or at the outlying hospital. Regulations have been developed to assure proper patient selection, quality care, safety, and minimization of misuse of this expensive resource. Images Fig. 1. PMID:3058056

  1. Helicopter air resonance modeling and suppression using active control

    NASA Technical Reports Server (NTRS)

    Takahashi, M. D.; Friedmann, P. P.

    1991-01-01

    A coupled rotor/fuselage helicopter analysis with the important effects of blade torsional flexibility, unsteady aerodynamics, and forward flight is presented. Using this mathematical model, a nominal configuration is selected with an air resonance instability throughout most of its flight envelope. A multivariable compensator is then designed using two swashplate inputs and a single-body roll rate measurement. The controller design is based on the linear quadratic Gaussian technique and the loop transfer recovery method. The controller is shown to suppress the air resonance instability throughout a wide range of helicopter loading conditions and forward flight speeds.

  2. MH-60R Multi-Mission Helicopter (MH-60R)

    DTIC Science & Technology

    2013-12-01

    Helicopter Concept of Operations that replaces the aging SH -60B and SH - 60F helicopters. The avionics upgrades over the existing SH -60B/F include: a glass...fleet as of March 24, 2014 with 13 of 17 prospective MH- 60R squadrons having been established or transitioned from SH -60Bs. Full Rate Production...Aircraft = 34.5 -- Total Operating Aircraft Years = 4,618 Antecedent Information: The antecedent system is the SH -60B/F aircraft. All costs are from the

  3. Research requirements to improve reliability of civil helicopters

    NASA Technical Reports Server (NTRS)

    Dougherty, J. J., III; Barrett, L. D.

    1978-01-01

    The major reliability problems of the civil helicopter fleet as reported by helicopter operational and maintenance personnel are documented. An assessment of each problem is made to determine if the reliability can be improved by application of present technology or whether additional research and development are required. The reliability impact is measured in three ways: (1) The relative frequency of each problem in the fleet. (2) The relative on-aircraft manhours to repair, associated with each fleet problem. (3) The relative cost of repair materials or replacement parts associated with each fleet problem. The data reviewed covered the period of 1971 through 1976 and covered only turbine engine aircraft.

  4. Maneuver Acoustic Flight Test of the Bell 430 Helicopter

    NASA Technical Reports Server (NTRS)

    Watts, Michael E.; Snider, Royce; Greenwood, Eric; Baden, Joel

    2012-01-01

    A cooperative flight test by NASA, Bell Helicopter and the U.S. Army to characterize the steady state acoustics and measure the maneuver noise of a Bell Helicopter 430 aircraft was accomplished. The test occurred during June/July, 2011 at Eglin Air Force Base, Florida. This test gathered a total of 410 data points over 10 test days and compiled an extensive data base of dynamic maneuver measurements. Three microphone configurations with up to 31 microphones in each configuration were used to acquire acoustic data. Aircraft data included DGPS, aircraft state and rotor state information. This paper provides an overview of the test.

  5. Diagnosis of helicopter gearboxes using structure-based networks

    NASA Technical Reports Server (NTRS)

    Jammu, Vinay B.; Danai, Kourosh; Lewicki, David G.

    1995-01-01

    A connectionist network is introduced for fault diagnosis of helicopter gearboxes that incorporates knowledge of the gearbox structure and characteristics of the vibration features as its fuzzy weights. Diagnosis is performed by propagating the abnormal features of vibration measurements through this Structure-Based Connectionist Network (SBCN), the outputs of which represent the fault possibility values for individual components of the gearbox. The performance of this network is evaluated by applying it to experimental vibration data from an OH-58A helicopter gearbox. The diagnostic results indicate that the network performance is comparable to those obtained from supervised pattern classification.

  6. Civil helicopter noise assessment study Boeing-Vertol model 347. [recommendations for reduction of helicopter noise levels

    NASA Technical Reports Server (NTRS)

    Hinterkeuser, E. G.; Sternfeld, H., Jr.

    1974-01-01

    A study was conducted to forecast the noise restrictions which may be imposed on civil transport helicopters in the 1975-1985 time period. Certification and community acceptance criteria were predicted. A 50 passenger tandem rotor helicopter based on the Boeing-Vertol Model 347 was studied to determine the noise reductions required, and the means of achieving them. Some of the important study recommendations are: (1) certification limits should be equivalent to 95 EPNdb at data points located at 500 feet to each side of the touchdown/takeoff point, and 1000 feet from this point directly under the approach and departure flight path. (2) community acceptance should be measured as Equivalent Noise Level (Leq), based on dBA, with separate limits for day and night operations, and (3) in order to comply with the above guidelines, the Model 347 helicopter will require studies and tests leading to several modifications.

  7. Stroboscope Controller for Imaging Helicopter Rotors

    NASA Technical Reports Server (NTRS)

    Jensen, Scott; Marmie, John; Mai, Nghia

    2004-01-01

    A versatile electronic timing-and-control unit, denoted a rotorcraft strobe controller, has been developed for use in controlling stroboscopes, lasers, video cameras, and other instruments for capturing still images of rotating machine parts especially helicopter rotors. This unit is designed to be compatible with a variety of sources of input shaftangle or timing signals and to be capable of generating a variety of output signals suitable for triggering instruments characterized by different input-signal specifications. It is also designed to be flexible and reconfigurable in that it can be modified and updated through changes in its control software, without need to change its hardware. Figure 1 is a block diagram of the rotorcraft strobe controller. The control processor is a high-density complementary metal oxide semiconductor, singlechip 8-bit microcontroller. It is connected to a 32K x 8 nonvolatile static random-access memory (RAM) module. Also connected to the control processor is a 32K 8 electrically programmable read-only-memory (EPROM) module, which is used to store the control software. Digital logic support circuitry is implemented in a field-programmable gate array (FPGA). A 240 x 128-dot, 40- character 16-line liquid-crystal display (LCD) module serves as a graphical user interface; the user provides input through a 16-key keypad mounted next to the LCD. A 12-bit digital-to-analog converter (DAC) generates a 0-to-10-V ramp output signal used as part of a rotor-blade monitoring system, while the control processor generates all the appropriate strobing signals. Optocouplers are used to isolate all input and output digital signals, and optoisolators are used to isolate all analog signals. The unit is designed to fit inside a 19-in. (.48-cm) rack-mount enclosure. Electronic components are mounted on a custom printed-circuit board (see Figure 2). Two power-conversion modules on the printedcircuit board convert AC power to +5 VDC and 15 VDC, respectively.

  8. Transmission eigenvalues

    NASA Astrophysics Data System (ADS)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  9. Automatic transmission

    SciTech Connect

    Miura, M.; Aoki, H.

    1988-02-02

    An automatic transmission is described comprising: an automatic transmission mechanism portion comprising a single planetary gear unit and a dual planetary gear unit; carriers of both of the planetary gear units that are integral with one another; an input means for inputting torque to the automatic transmission mechanism, clutches for operatively connecting predetermined ones of planetary gear elements of both of the planetary gear units to the input means and braking means for restricting the rotation of predetermined ones of planetary gear elements of both of the planetary gear units. The clutches are disposed adjacent one another at an end portion of the transmission for defining a clutch portion of the transmission; a first clutch portion which is attachable to the automatic transmission mechanism portion for comprising the clutch portion when attached thereto; a second clutch portion that is attachable to the automatic transmission mechanism portion in place of the first clutch portion for comprising the clutch portion when so attached. The first clutch portion comprising first clutch for operatively connecting the input means to a ring gear of the single planetary gear unit and a second clutch for operatively connecting the input means to a single gear of the automatic transmission mechanism portion. The second clutch portion comprising a the first clutch, the second clutch, and a third clutch for operatively connecting the input member to a ring gear of the dual planetary gear unit.

  10. AQUIFER TRANSMISSIVITY

    EPA Science Inventory

    Evaluation of groundwater resources requires the knowledge of the capacity of aquifers to store and transmit ground water. This requires estimates of key hydraulic parameters, such as the transmissivity, among others. The transmissivity T (m2/sec) is a hydrauli...

  11. Frame junction vibration transmission with a modified frame deformation model.

    PubMed

    Moore, J A

    1990-12-01

    A previous paper dealt with vibration transmission through junctions of connected frame members where the allowed frame deformations included bending, torsion, and longitudinal motions [J.A. Moore, J. Acoust. Soc. Am. 88, 2766-2776 (1990)]. In helicopter and aircraft structures the skin panels can constitute a high impedance connection along the length of the frames that effectively prohibits in-plane motion at the elevation of the skin panels. This has the effect of coupling in-plane bending and torsional motions within the frame. This paper discusses the transmission behavior through frame junctions that accounts for the in-plane constraint in idealized form by assuming that the attached skin panels completely prohibit inplane motion in the frames. Also, transverse shear deformation is accounted for in describing the relatively deep web frame constructions common in aircraft structures. Longitudinal motion in the frames is not included in the model. Transmission coefficient predictions again show the importance of out-of-plane bending deformation to the transmission of vibratory energy in an aircraft structure. Comparisons are shown with measured vibration transmission data along the framing in the overhead of a helicopter airframe, with good agreement. The frame junction description has been implemented within a general purpose statistical energy analysis (SEA) computer code in modeling the entire airframe structure including skin panels.

  12. NASA/Army Rotorcraft Transmission Research, a Review of Recent Significant Accomplishments

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    1994-01-01

    A joint helicopter transmission research program between NASA Lewis Research Center and the U.S. Army Research Lab has existed since 1970. Research goals are to reduce weight and noise while increasing life, reliability, and safety. These research goals are achieved by the NASA/Army Mechanical Systems Technology Branch through both in-house research and cooperative research projects with university and industry partners. Some recent significant technical accomplishments produced by this cooperative research are reviewed. The following research projects are reviewed: oil-off survivability of tapered roller bearings, design and evaluation of high contact ratio gearing, finite element analysis of spiral bevel gears, computer numerical control grinding of spiral bevel gears, gear dynamics code validation, computer program for life and reliability of helicopter transmissions, planetary gear train efficiency study, and the Advanced Rotorcraft Transmission (ART) program.

  13. Transmission Efficiency Measurements and Correlations with Physical Characteristics of the Lubricant

    NASA Technical Reports Server (NTRS)

    Coy, J. J.; Mitchell, A. M.; Hamrock, B. J.

    1984-01-01

    Data from helicopter transmission efficiency tests were compared to physical properties of the eleven lubricants used in those tests. The tests were conducted with the OH-58 helicopter main rotor transmission. Efficiencies ranged from 98.3 to 98.8 percent. The data was examined for correlation of physical properties with efficiency. There was a reasonable correlation of efficiency with absolute viscosity if the viscosity was first corrected for temperature and pressure in the lubricated contact. Between lubricants, efficiency did not correlate well with viscosity at atmospheric pressure. Between lubricants, efficiency did not correlate well with calculated lubricant film forming capacity. Bench type sliding friction and wear measurements could not be correlated to transmission efficiency and component wear.

  14. 20. DISTANT HELICOPTER VIEW TO SOUTHEAST UP LITTLE ROCK CREEK ...

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

    20. DISTANT HELICOPTER VIEW TO SOUTHEAST UP LITTLE ROCK CREEK CANYON, WITH DAM AND RESERVOIR AT RIGHT CENTER. PALMDALE-LITTLEROCK DITCH, MARKED BY DENSE VEGETATION, CROSSES ROAD AT LOWER CENTER - Little Rock Creek Dam, Little Rock Creek, Littlerock, Los Angeles County, CA

  15. NASA helicopter helps fight brush fire at KSC

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA helicopter flies toward the source of the smoke to drop its load of water on a wildfire at KSC. Before being extinguished, the fire burned about 20 acres at a site near gate 2C on Kennedy Parkway North (route 3).

  16. CH-47F Improved Cargo Helicopter (CH-47F)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-278 CH-47F Improved Cargo Helicopter (CH-47F) As of FY 2017 President’s Budget Defense...Estimate RDT&E - Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be Determined TY

  17. CH-53K Heavy Lift Replacement Helicopter (CH-53K)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-390 CH-53K Heavy Lift Replacement Helicopter (CH-53K) As of FY 2017 President’s Budget...Estimate RDT&E - Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be Determined TY

  18. 77 FR 58971 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-25

    ... prompted by flight crew reports of deviations between the displayed attitude on the attitude display screen and the independent electromechanical standby attitude indicator. The proposed actions ] are intended... helicopters. EASA advises that a slow drift in the roll axis on the pilot's and co-pilot's attitude...

  19. Flight Test Guide (Part 61 Revised): Instrument Pilot: Helicopter.

    ERIC Educational Resources Information Center

    Federal Aviation Administration (DOT), Washington, DC. Flight Standards Service.

    The guide provides an outline of the skills required to pass the flight test for an Instrument Pilot Helicopter Rating under Part 61 (revised) of Federal Aviation Regulations. General procedures for flight tests are described and the following pilot operations outlined: maneuvering by reference to instruments, IFR navigation, instrument…

  20. 78 FR 18230 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... cabin vibration damper installed. This AD requires installing a vibration damper casing assembly on both sides of the helicopter. This AD was prompted by a crack and failure of a cabin vibration damper blade. The actions of this AD are intended to modify the cabin vibration damper assembly to prevent...

  1. 77 FR 43738 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-26

    ... EC130 B4 helicopters with a cabin vibration damper installed. This proposed AD is prompted by a crack and failure of a cabin vibration damper ] blade. The proposed actions are intended to modify the cabin vibration damper assembly to prevent contact with the flight controls in the event of a cabin...

  2. 78 FR 40956 - Airworthiness Directives; Eurocopter Deutschland (Eurocopter) Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-09

    ... helicopters with a Metro Aviation (Metro) vapor-cycle air conditioning kit installed in accordance with Supplemental Type Certificate (STC) No. SH3880SW. This AD requires repetitively inspecting the air conditioning... comments. Discussion STC No. SH3880SW approves the installation of the Metro vapor-cycle air...

  3. 77 FR 14310 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... helicopters. This proposed AD is prompted by an in-flight fire caused by ignition of hydraulic fluid leaking from a damaged forward (pitch) servo-control hydraulic hose. The proposed actions are intended to prevent the forward servo-control hydraulic hoses from becoming damaged and leaking hydraulic fluid...

  4. 78 FR 59306 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-26

    ... hydraulic hoist in helicopters equipped with certain parts and configurations until a hoist beam lower... advises that during a hoisting operation, a hydraulic hoist cable jammed against the base of the...-up electrical hoist and safely brought on board. However, the jamming of the hydraulic hoist...

  5. Design of helicopter rotor blades for optimum dynamic characteristics

    NASA Technical Reports Server (NTRS)

    Peters, D. A.; Ko, T.; Korn, A.; Rossow, M. P.

    1985-01-01

    The mass and stiffness distributions for helicopter rotor blades are tailored in such a way to give a predetermined placement of blade natural frequencies. The optimal design is pursued with respect of minimum weight, sufficient inertia, and reasonable dynamic characteristics. Finite element techniques are used as a tool. Rotor types include hingeless, articulated, and teetering.

  6. Design of helicopter rotor blades for optimum dynamic characteristics

    NASA Technical Reports Server (NTRS)

    Peters, D. A.; Ko, T.; Korn, A.; Rossow, M. P.

    1984-01-01

    The optimal design of helicopter rotor blades is addressed. The forced response of an initial (i.e., non-optimized) blade to those of a final (optimized) blade are compared. Response of starting design and optimal designs for varying forcing frequencies, blade response to harmonics of rotor speed, and derivation of mass and stiffness matrices or functions of natural frequencies are discussed.

  7. 77 FR 63285 - Airworthiness Directives; Brantly International, Inc. Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-16

    ... International, Inc. (Brantly) Model B-2, Model B-2A, and Model B-2B helicopters with a certain main rotor blade. This proposed AD was prompted by multiple reports of main rotor (M/R) blade cracks and an accident in which a crack that originated near the M/R blade trailing edge resulted in the loss of a large...

  8. New fire-fighting water bucket is lifted by helicopter

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A NASA helicopter lifts a high-impact-resistant flexible plastic bucket that will be used for fire protection on property and buildings at Kennedy Space Center. Known as the 'Bambi' bucket, the 324-gallon container will also support the Fish and Wildlife Service for controlled burns plus any wild fires in the area.

  9. Extending helicopter operations to meet future integrated transportation needs.

    PubMed

    Stanton, Neville A; Plant, Katherine L; Roberts, Aaron P; Harvey, Catherine; Thomas, T Glyn

    2016-03-01

    Helicopters have the potential to be an integral part of the future transport system. They offer a means of rapid transit in an overly populated transport environment. However, one of the biggest limitations on rotary wing flight is their inability to fly in degraded visual conditions in the critical phases of approach and landing. This paper presents a study that developed and evaluated a Head up Display (HUD) to assist rotary wing pilots by extending landing to degraded visual conditions. The HUD was developed with the assistance of the Cognitive Work Analysis method as an approach for analysing the cognitive work of landing the helicopter. The HUD was tested in a fixed based flight simulator with qualified helicopter pilots. A qualitative analysis to assess situation awareness and workload found that the HUD enabled safe landing in degraded conditions whilst simultaneously enhancing situation awareness and reducing workload. Continued development in this area has the potential to extend the operational capability of helicopters in the future.

  10. Optimal helicopter trajectory planning for terrain following flight

    NASA Technical Reports Server (NTRS)

    Menon, P. K. A.

    1990-01-01

    Helicopters operating in high threat areas have to fly close to the earth surface to minimize the risk of being detected by the adversaries. Techniques are presented for low altitude helicopter trajectory planning. These methods are based on optimal control theory and appear to be implementable onboard in realtime. Second order necessary conditions are obtained to provide a criterion for finding the optimal trajectory when more than one extremal passes through a given point. A second trajectory planning method incorporating a quadratic performance index is also discussed. Trajectory planning problem is formulated as a differential game. The objective is to synthesize optimal trajectories in the presence of an actively maneuvering adversary. Numerical methods for obtaining solutions to these problems are outlined. As an alternative to numerical method, feedback linearizing transformations are combined with the linear quadratic game results to synthesize explicit nonlinear feedback strategies for helicopter pursuit-evasion. Some of the trajectories generated from this research are evaluated on a six-degree-of-freedom helicopter simulation incorporating an advanced autopilot. The optimal trajectory planning methods presented are also useful for autonomous land vehicle guidance.

  11. Helicopter anti-torque system using fuselage strakes

    NASA Technical Reports Server (NTRS)

    Kelley, Henry L. (Inventor); Wilson, John C. (Inventor)

    1987-01-01

    The improvement of the helicopter torque control system is discussed. At low to medium forward speeds helicopter performance is limited by the effectiveness of the means for counteracting main rotor torque and controlling sideslip airloads. These problems may be overcome by mounting strakes on the aft fuselage section. For single rotor helicopters whose main rotor rotates counter-clockwise as viewed from above, one of the strakes would be mounted in the upper lefthand quadrant and the second in the lower left hand quadrant. The strakes alter the air flow around the fuselage by separating the flow so as to produce lateral airloads on the tail boom which oppose main-rotor torque. The upper strake operates in a right crosswind to oppose main rotor torque, and the lower strake has effect in left crosswinds. The novelty of this invention resides in the simple and economical manner in which the helicopter tail boom may be modified by the addition of strakes in order to increase torque control, and reduce the need for supplemental mechanical means of torque control.

  12. 78 FR 7641 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... 200 amp starter generator from the engine is above the consumption capacity for the specified Eurocopter model helicopters. Excessive power consumption of the starter generator reduces the engine surge... substantial direct effect on the States, on the relationship between the national government and the...

  13. 77 FR 64709 - Airworthiness Directives; MD Helicopters, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-23

    ...), Model MD900 helicopters. The existing AD requires a visual inspection, and if necessary, an eddy current...-117, dated January 14, 2011 (SB). The SB specifies an initial 100-hour and recurring 300-hour visual... hub. (ii) If the lower hub is not replaced as a result of the visual inspection required by...

  14. Astronaut Frank Borman hoisted from water by recovery helicopter

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronaut Frank Borman, command pilot of the Gemini 7 space flight, is hoisted from the water by a recovery helicopter from the Aircraft Carrier U.S.S. Wasp. Below him, Navy divers sit in the life raft next to the Gemini spacecraft.

  15. Two-Dimensional Fourier Transform Applied to Helicopter Flyover Noise

    NASA Technical Reports Server (NTRS)

    Santa Maria, Odilyn L.

    1999-01-01

    A method to separate main rotor and tail rotor noise from a helicopter in flight is explored. Being the sum of two periodic signals of disproportionate, or incommensurate frequencies, helicopter noise is neither periodic nor stationary, but possibly harmonizable. The single Fourier transform divides signal energy into frequency bins of equal size. Incommensurate frequencies are therefore not adequately represented by any one chosen data block size. A two-dimensional Fourier analysis method is used to show helicopter noise as harmonizable. The two-dimensional spectral analysis method is first applied to simulated signals. This initial analysis gives an idea of the characteristics of the two-dimensional autocorrelations and spectra. Data from a helicopter flight test is analyzed in two dimensions. The test aircraft are a Boeing MD902 Explorer (no tail rotor) and a Sikorsky S-76 (4-bladed tail rotor). The results show that the main rotor and tail rotor signals can indeed be separated in the two-dimensional Fourier transform spectrum. The separation occurs along the diagonals associated with the frequencies of interest. These diagonals are individual spectra containing only information related to one particular frequency.

  16. At Issue: Helicopter Parents and Millennial Students, an Annotated Bibliography

    ERIC Educational Resources Information Center

    Pricer, Wayne F.

    2008-01-01

    Technological advances have made it easy for parents and children--many of them students--to communicate instantaneously. Devices and technologies such as cell phones, laptops, texting, and e-mail all enable various forms of instant communication. "Helicopter parents" are regarded as very overprotective and overly involved in the affairs of their…

  17. 78 FR 25380 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-01

    ...-degree frame for a crack, and repair of the frame if there is a crack. This AD was prompted by the discovery of a crack in the 9-degree frame of a Eurocopter Model AS-365N2 helicopter, and these cracks could... specified by this AD are intended to detect a crack in the 9-degree frame to prevent loss of...

  18. 78 FR 57047 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-17

    ..., to require inspecting for a crack in the control lever attachment yokes, and if needed, replacing the... lead to cracking. A crack in the control lever attachment yokes could cause a loss of tail rotor pitch... AS350 and AS355 helicopters. The NPRM proposed to require inspecting for a crack in the control...

  19. 78 FR 40954 - Airworthiness Directives; Various Restricted Category Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-09

    ... inspection (MPI) of the fittings for a crack, and if there is a crack, replacing the fitting with an airworthy fitting. This AD is prompted by reports of cracked fittings on Bell model helicopters and the.... These actions are intended to detect a crack in a fitting, which may lead to failure of a fitting,...

  20. 77 FR 69556 - Airworthiness Directives; Eurocopter Deutschland Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-20

    ..., loss of systems required for continued safe flight and landing, and subsequent loss of control of the...-BK117 C-2 helicopters with certain Generator Control Units (GCU) installed. This AD requires replacing the GCUs. This AD was prompted by reports of internal short circuits in certain GCUs. These...

  1. 77 FR 30230 - Airworthiness Directives; Eurocopter Deutschland Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-22

    ... the loss of systems required for continued safe flight and landing, and subsequent loss of control of... Deutschland GmbH Model MBB-BK117 C-2 helicopters with certain Generator Control Units (GCU) installed. This proposed AD is prompted by reports of internal short circuits in certain GCUs. The proposed actions...

  2. 78 FR 17591 - Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... system fuel filters and re-identify the fuel tank fuel filter and fuel control assembly bracket. The... malfunction of an internal valve, power loss at a critical phase of flight, and loss of control of the... helicopters to require replacing each forward and aft fuel system 40 micron fuel filter element with a...

  3. A laser imaging system for helicopter avoidance obstacle

    NASA Astrophysics Data System (ADS)

    Wang, WeiRan; Yuan, HongChun; Jin, Yuan

    2006-09-01

    Rotorcraft flying in low-altitude is endangered by power lines or telephone wires. The development of automated tools that can detect obstacles in the flight path and warn the crew would significantly reduce the workload of pilot and increase the safety. Detection and warning are rudimental demand and desire for Helicopter Avoidance Obstacle System (HAOS). And that, An advanced HAOS may be capable of classifying thin obstacles and enhanced vision with distances of obstacles. A laser 3D imaging system for helicopter avoidance obstacle (HAO) had been developed successfully. The laser 3D imaging helicopter avoidance obstacle system can not only detect thin obstacles but also catch more information of all objects of the area in front of the helicopter as possible. Then the information is transformed into intuitionist 3D image modality. In this paper, special features and characteristic of the laser imaging system for HAO are analyzed and discussed. Several design gist for this system are proposed. Especially, the developed zero backlash imaging technology and real-time dynamic imaging synchronizing with radar space scanning are described. The technique implementation problem and the system structure are given as well. Finally, the results of system ground test are presented. The ground test of the developed laser imaging system has demonstrated that the developed imaging system performance can achieve and satisfy commendably the requirements of the mission to prevent "wire strike".

  4. 77 FR 43734 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-26

    ... AS350BA helicopters with certain AERAZUR emergency flotation gear container assemblies installed. This proposed AD would require replacing each affected emergency flotation gear container assembly (container... recognition that container assemblies with an intended operating limitation of 10 years may not have...

  5. CATEGORY II ARCTIC EVALUATION OF THE YCH-47A HELICOPTER.

    DTIC Science & Technology

    Stability Augmentation System ) operation, delamination of rotor blade fiberglass skins, and extreme difficulty in ground handling on hard packed snow, ice, or similar slippery surfaces. In order for the helicopter to be suitable for low temperature operation, new or modified rotor blades with assured structural integrity must be incorporated along with other improvements recommended in this report.

  6. A review of risk analysis and helicopter air ambulance accidents.

    PubMed

    Nix, Sam; Buckner, Steven; Cercone, Richard

    2014-01-01

    The Federal Aviation Administration announced a final rule in February 2014 that includes a requirement for helicopter air ambulance operators to institute preflight risk analysis programs. This qualitative study examined risk factors that were described in 22 preliminary, factual, and probable cause helicopter air ambulance accident and incident reports that were initiated by the National Transportation Safety Board between January 1, 2011, and December 31, 2013. Insights into the effectiveness of existing preflight risk analysis strategies were gained by comparing these risk factors with the preflight risk analysis guidance that is published by the Federal Aviation Administration in the Flight Standards Information Management System. When appropriate, a deeper understanding of the human factors that may have contributed to occurrences was gained through methodologies that are described in the Human Factors Analysis and Classification System. The results of this study suggest that there are some vulnerabilities in existing preflight risk analysis guidelines that may affect safety in the helicopter air ambulance industry. The likelihood that human factors contributed to most of the helicopter air ambulance accidents and incidents that occurred during the study period was also evidenced. The results of this study suggest that effective risk analysis programs should provide pilots with both preflight and in-flight resources.

  7. Past applications and future potential of variable stability research helicopters

    NASA Technical Reports Server (NTRS)

    Hindson, W. S.

    1982-01-01

    The historical development of variable-stability research helicopters and some of their previous applications are presented as a guide for assessing their future potential. The features of three general-purpose rotary-wing flight research aircraft that provide complementary capabilities are described briefly, and a number of future applications are proposed.

  8. Air To Air Helicopter Fire Control Equations and Software Generation.

    DTIC Science & Technology

    1979-11-01

    FORM I. REPORT NUMBER 12. GOVT ACCE NO S.SCIP1INTIS CATALOG NUMBER Air To Air Helicop~ter Fire Control 1I t 31Au Equations and Software Generation oN.m...differentiator in order to model the way that they are added in the track loop before the capacitor coupled tachometer feedback. AIRSIM Data Representative output

  9. 78 FR 65871 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-04

    ..., separation, or interference. This AD is prompted by reports of cracks, separation of the IGB fairing from the... shaft. These actions are intended to detect a crack and prevent separation of the IGB fairing, which..., IGB fairing, and attachment supports for a crack, separation, or interference. For helicopters with...

  10. The need for a dedicated public service helicopter design

    NASA Technical Reports Server (NTRS)

    Morrison, R.

    1984-01-01

    The need to provide the necessary funding to research, design and contract the building of an advanced technology rotorcraft that will meet the mission demands of public service (fire, police, paramedics and rescue) operators is discussed. Noise and cost factors, the greatest objections on the part of many police and public adminstrators are addressed. The growth of helicopter utilization in public service is documented.

  11. Revolutionary Concepts for Helicopter Noise Reduction: SILENT Program

    NASA Technical Reports Server (NTRS)

    Edwards, Bryan; Cox, Charles; Booth, Earl R., Jr. (Technical Monitor)

    2002-01-01

    As part of a NASA initiative to reduce helicopter main rotor noise, a Phase 1 study has been performed of candidate noise reduction concepts. Both conventional and novel design technologies have been analyzed that reduce the community impact of helicopter operations. In this study the noise reduction potential and design implications are assessed for conventional means of noise reduction, e.g., tip speed reduction, tip shapes and airfoil tailoring, and for two innovative design concepts: modulated blade spacing and x-force control. Main rotor designs that incorporate modulated blade spacing are shown to have reduced peak noise levels in most flight operations. X-force control alters the helicopter's force balance whereby the miss distance between main rotor blades and shed vortices can be controlled. This control provides a high potential to mitigate BVI noise radiation. Each concept is evaluated using best practice design and analysis methods, achieving the study's aim to significantly reduce noise with minimal performance degradation and no vibration increase. It is concluded that a SILENT main rotor design, incorporating the modulated blade spacing concept, offers significantly reduced noise levels and the potential of a breakthrough in how a helicopter's sound is perceived and judged. The SILENT rotor represents a definite advancement in the state-of-the-art and is selected as the design concept for demonstration in Phase 2. A Phase 2 Implementation Plan is developed for whirl cage and wind tunnel evaluations of a scaled model SILENT rotor.

  12. From Self-Flying Helicopters to Classrooms of the Future

    ERIC Educational Resources Information Center

    Young, Jeffrey R.

    2012-01-01

    On a summer day four years ago, a Stanford University computer-science professor named Andrew Ng held an unusual air show on a field near the campus. His fleet of small helicopter drones flew under computer control, piloted by artificial-intelligence software that could teach itself to fly after watching a human operator. By the end of the day,…

  13. 77 FR 36220 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-18

    ...-366G1 helicopters. This proposed AD is prompted by reports of corrosion on the main gearbox (MGB) casing... that the corrosion was associated with sealing compound on the lower part of the fitting/casing attachment. The proposed actions are intended to detect corrosion on the MGB casing, which could lead to...

  14. 78 FR 44043 - Airworthiness Directives; Eurocopter France Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ... EC225LP helicopters. This proposed AD ] would require inspecting the swashplates for corrosion or a crack... discovery of corrosion on the swashplates when the main rotor hub (MRH) assemblies were reconditioned. The proposed actions are intended to detect corrosion or a crack in the swashplates, which could lead...

  15. 77 FR 32884 - Airworthiness Directives; Eurocopter Deutschland GMBH Helicopters

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... engine installed, which has an FCU that has not been modified with Turbomeca Modification TU 358. That... modifying both engines with Turbomeca Modification TU 358 would be terminating action for the requirements... helicopters with FCUs that have not been modified by Turbomeca modification TU 358, for takeoffs,...

  16. Flight vibrations and bleeding in helicoptered patients with pelvic fracture.

    PubMed

    Carchietti, Elio; Cecchi, Adriana; Valent, Francesca; Rammer, Raphael

    2013-01-01

    Depending on their amplitude and frequency, vibrations may facilitate bleeding and worsen the prognosis of patients with pelvic fractures transported by helicopter emergency medical services (HEMS). We measured the range of frequencies and amplitudes of forced vibrations produced by the helicopter used by the HEMS of the Italian Friuli Venezia Giulia region on the pelvis of transported persons. We performed 3 flight tests with 3 different volunteers (mass 70, 80, and 90 kg, respectively) loaded on the helicopter's stretcher and recorded the amplitudes and frequencies of vibrations through a triaxis sensor placed on the HEMS stretcher in the pelvis area. The flight profile planned was identical for each of the 3 iterations. Over the whole flight, the frequencies of vibration were between 26.4 and 53.5 Hz, and the greastest amplitude was 0.035 mm. The vibrations recorded in the helicopter may facilitate bleeding in unstable fractures. In the management of patients with pelvic fractures, HEMS crews should provide prehospital care that includes the use of specific splinting devices in addition to the spinal board, which allows an early immobilization of fractures and the limitation of pelvic motion.

  17. Astronaut John Young hoisted aboard helicopter during water egress training

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronauts John W. Young, Gemini 10 command pilot, is hoisted up to a U.S. Coast Guard helicopter during water egress training in the Gulf of Mexico. A team of Manned Spaceflight Center (MSC) swimmers assists in the exercise. The Static Article 5 spacecraft can be seen in the water.

  18. Data Input, Processing and Presentation. [helicopter rotor balance measurement

    NASA Technical Reports Server (NTRS)

    Langer, H. J.

    1984-01-01

    The problems of data acquisition, processing and display are investigated in the case of a helicopter rotor balance. The types of sensors to be employed are discussed in addition to their placement and application in wind tunnel trials. Finally, the equipment for data processing, evaluation and storage are presented with a description of methods.

  19. Helicopter Approach Capability Using the Differential Global Positioning System

    NASA Technical Reports Server (NTRS)

    Kaufmann, David N.

    1994-01-01

    The results of flight tests to determine the feasibility of using the Global Positioning System (GPS) in the Differential mode (DGPS) to provide high accuracy, precision navigation and guidance for helicopter approaches to landing are presented. The airborne DGPS receiver and associated equipment is installed in a NASA UH-60 Black Hawk helicopter. The ground-based DGPS reference receiver is located at a surveyed test site and is equipped with a real-time VHF data link to transmit correction information to the airborne DGPS receiver. The corrected airborne DGPS information, together with the preset approach geometry, is used to calculate guidance commands which are sent to the aircraft's approach guidance instruments. The use of DGPS derived guidance for helicopter approaches to landing is evaluated by comparing the DGPS data with the laser tracker truth data. The errors indicate that the helicopter position based on DGPS guidance satisfies the International Civil Aviation Organization (ICAO) Category 1 (CAT 1) lateral and vertical navigational accuracy requirements.

  20. Ground vibration tests of a helicopter structure using OMA techniques

    NASA Astrophysics Data System (ADS)

    Ameri, N.; Grappasonni, C.; Coppotelli, G.; Ewins, D. J.

    2013-02-01

    This paper is focused on an assessment of the state-of-the-art of operational modal analysis (OMA) methodologies in estimating modal parameters from output responses on helicopter structures. For this purpose, a ground vibration test was performed on a real helicopter airframe. In the following stages, several OMA techniques were applied to the measured data and compared with the results from typical input-output approach. The results presented are part of a more general research activity carried out in the Group of Aeronautical Research and Technology in Europe (GARTEUR) Action Group 19, helicopter technical activity, whose overall objective is the improvement of the structural dynamic finite element models using in-flight test data. The structure considered is a medium-size helicopter, a time-expired Lynx Mk7 (XZ649) airframe. In order to have a comprehensive analysis, the behaviour of both frequency- and time-domain-based OMA techniques are considered for the modal parameter estimates. An accuracy index and the reliability of the OMA methods with respect to the standard EMA procedures, together with the evaluation of the influence of the experimental setup on the estimate of the modal parameters, will be presented in the paper.