Download or read book Vibration and Acoustic Environment of OH 6A Helicopter Configured with and Using the XM 27 Armament System written by and published by . This book was released on 1975 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibration and acoustic measurements were made on an OH-6A helicopter equipped with a XM-27 armament system to determine the vibration and acoustic environment throughout the vehicle. Tape recordings from 60 accelerometers and 11 microphones were made during all flight conditions including gunfire. Spectrum analyses were performed to obtain vibratory double amplitude, acceleration power spectral density, and sound pressure level, versus frequency. Amplitude probability density plots are included. Measured vibration and acoustic data are compared with military standards and specification requirements.
Download or read book The Shock and Vibration Bulletin written by and published by . This book was released on 1977 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Military Standard written by United States. Department of Defense and published by . This book was released on 1984 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Notices of Changes in Classification Distribution and Availability written by and published by . This book was released on 1986 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vibration and Acoustic Environment of UH 1C Helicopter Configured with and Using M 5 and XM 21 Armament written by Virgil C. McIntosh and published by . This book was released on 1974 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibration and acoustic measurements were made on a UH-1C helicopter equipped with machine guns, a grenade launcher, and rocket launchers to determine vibration and acoustic environment throughout the vehicle. Tape recordings from 96 accelerometers and 12 microphones were made during all flight conditions and armament operation. Spectrum analyses were performed to obtain vibratory double amplitude, acceleration power spectral density, and sound pressure level versus frequency. Amplitude probability density plots also are included. Measured vibration and acoustic data are compared with military standards and specifications requirements. (Author).
Download or read book Engineering Flight Test product Improvement Test of Production Oh 6a Helicopter Unarmed and Armed with the Xm 27e1 Weapon System Phase D written by John I. Nagata and published by . This book was released on 1968 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: An engineering flight test of the OH-6A helicopter equipped with the XM-27E1 armament subsystem was conducted at Edwards Air Force Base, California, by the US Army Aviation Test Activity. The objective of the test was to determine what effects the armament subsystem had on the performance and stability and control characteristics as compared with an aircraft without the armament subsystem. The testing consisted of 10.25 productive test hours and was conducted from 2 October 1967 through 24 October 1967. Performance degradation resulted from the drag imposed by the armament subsystem. The specific range at 2400 pounds gross weight decreased by 8 percent. The stability and control characteristics were essentially unchanged by the addition of the armament subsystem. During firing tests, there were no adverse control problems. However, during flight at 12 degrees left sideslip at 105 knots indicated airspeed (KIAS), the upper right windshield imploded. The sideslip angle should be limited to 8 degrees or less at 100 KIAS until the cause of the implosion can be determined. Noise level and vibration tests should be conducted during firing with the 'doors off' configuration. The performance data should be incorporated into the operator's manual. (Author).
Download or read book Application of Higher Harmonic Blade Feathering on the OH 6A Helicopter for Vibration Reduction written by F. K. Straub and published by . This book was released on 1986 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book OH 6A Propulsion System Vibration Investigation written by R. J. Sullivan and published by . This book was released on 1975 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was made of means to improve helicopter engine/airframe vibratory interface compatibility. The study was based on the characteristics of the OH-6A helicopter and the T63 engine in order to utilize existing data to validate the methodology produced in the study. Available engine and airframe data was reviewed and used to prepare a vibration spectrum for a typical mission. Airframe mobility data was acquired during a ground shake test. A finite element model of the OH-6A airframe was prepared and was coupled to a model of the T63 engine, which was based on mobility data supplied by the engine manufacturer. The airframe and engine models were combined using a modal coupling technique, and reasonable correlation with test data was obtained. An impedance/mobility coupling technique is recommended where many flexible modes are in the frequency ranges that could be excited by main-rotor-induced vibratory forces. Based on the study, recommendations were prepared and circulated to engine manufacturers for future engine vibration specification, vibration parameter selection, and data reduction. The results of the survey and the proposed recommendations are presented.
Download or read book Vibration and Acoustic Environment of AH 1G Helicopter written by and published by . This book was released on 1975 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibration and acoustic measurements were made on an AH-1G Helicopter equipped with 7.62 millimeter machine guns, a 40-millimeter grenade launcher, and 7-tube and 19-tube, 2.75-inch rocket launchers to determine the vibration and acoustic environment throughout the helicopter. Tape recordings from 96 accelerometers and 12 microphones were made during various flight conditions and during armament fire. Spectrum analyses were conducted to determine vibratory double amplitude (DA), acceleration, power spectral density (PSD), and sound pressure levels (SPL) versus frequency. Amplitude probability density (APD) plots also are included. Measured vibration and acoustic data are compared with military standards and specification requirements.
Download or read book Results of the Noise Measurement Program on a Standard and Modified OH 6A Helicopter written by Herbert R. Henderson and published by . This book was released on 1973 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preliminary Vibration Survey of a Suspended Full scale OH 6A Helicopter from 0 to 45 HZ written by John H. Harris and published by . This book was released on 1996 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efforts to establish a helicopter research program in structural dynamics at NPS were greatly enhanced when the U. S. Army donated two OH-6A light observation helicopters. One of the helicopters is reserved for ground vibration testing and dynamics research. Vibration measurements are extremely important in predicting and understanding an aircraft's dynamic behavior and durability. A comparison of a helicopters natural frequencies and those frequencies transmitted to the airframe through the rotor system can alert the designer/evaluator to possible dynamic problems. This thesis establishes a baseline vibration test program on the OH-6A helicopter for future testing and comparison to analytic models. The goal of the research is to establish natural frequencies (eigenvalues) principal mode shapes (eigenvectors), and damping characteristics of the OH-6A and to compare these values to test and analytical data obtained from the McDonnell Douglas Helicopter Company.
Download or read book Preliminary Vibration Survey of a Suspended Full Scale OH 6A Helicopter from 0 to 45 Hz written by John H. Harris and published by . This book was released on 1996-03-01 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efforts to establish a helicopter research program in structural dynamics at NPS were greatly enhanced when the U. S. Army donated two OH-6A light observation helicopters. One of the helicopters is reserved for ground vibration testing and dynamics research. Vibration measurements are extremely important in predicting and understanding an aircraft's dynamic behavior and durability. A comparison of a helicopters natural frequencies and those frequencies transmitted to the airframe through the rotor system can alert the designer/evaluator to possible dynamic problems. This thesis establishes a baseline vibration test program on the OH-6A helicopter for future testing and comparison to analytic models. The goal of the research is to establish natural frequencies (eigenvalues) principal mode shapes (eigenvectors), and damping characteristics of the OH-6A and to compare these values to test and analytical data obtained from the McDonnell Douglas Helicopter Company.
Download or read book Instrument Panel and Avionics Compartment Environmental Survey Production OH 58A Helicopter written by Emmett J. Lang and published by . This book was released on 1972 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibration and temperature measurement tests were conducted on a production OH-58A helicopter to define the instrument and avionics vibration and temperature environment for both weapons-firing and nonweapons-firing flight conditions. Testing was performed by the United States Army Aviation Systems Test Activity, Edwards Air Force Base, California, between 27 May and 24 June 1971. The testing consisted of four flights, totaling 3.0 productive test hours. Vibration data were recorded from seven triaxial accelerometer locations for 29 flight conditions, and narrow-band spectral analyses were performed on the vibration data. The results of the spectral analyses were summarized by use of statistical methods. The primary source of low-frequency vibrations was the main rotor, and the primary source of high-frequency vibrations was gunfire. The characteristic of the instrument and avionics vibration isolation mounts to amplify the vibrations at the main rotor driving frequencies is a short coming. Interior cabin temperatures of 25 C and 6 C above the ambient air temperature were recorded for static and in-flight conditions, respectively. (Author).
Download or read book OH 6A Propulsion System Vibration Investigation written by and published by . This book was released on 1975 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Application of Chaos Methods to Helicopter Vibration Reduction Using Higher Harmonic Control written by Martinus M. Sarigul-Klijn and published by . This book was released on 1990 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chaos is a discipline used in understanding complex nonlinear dynamics. The geometric and topological methods of Chaos theory are applied, for the first time, to the study of flight test data. Data analyzed is from the McDonnell Douglas OH-6A Higher Harmonic Control (HHC) test aircraft. HHC is an active control system used to suppress helicopter vibrations. Some of the first practical applications of Chaos methods are demonstrated with the HHC data. Although helicopter vibrations are mostly periodic, evidence of chaos was found. The presenc3e of a strange attractor was shown by computing a positive Lyapunov exponent and computing a non-integer fractal correlation dimension. Also, a broad band Fourier spectrum and a well defined attractor in pseudo phase space are observed. A limit exists to HHC vibration reduction due to the presence of chaos. A new technique based on a relationship between the Chaos methods (the Poincare section and Van der Pol plane) and the vibration amplitude and phase was discovered. This newly introduced technique results in the following: 1) it gives the limits of HHC vibration reduction, 2) it allows rapid determination of best phase for a HHC controller, 3) it determines the minimum HHC controller requirement for any helicopter from a few minutes duration of flight test data (for the OH-6A, a scheduled gain controller for HHC appears to be adequate for steady level flight), 4) it shows that the HHC controller transfer matrix is linear and repeatable when the vibrations are defined in the?Rotor Time Domain? and that the matrix is nonlinear and nonrepeatable when the vibrations are defined in the?Clock Time Domain.? This technique will reduce future HHC flight test requirements. Further, the technique does not require the helicopter to be equipped with HHC. These methods may be applicable to other vibration control and flight testing problems.
Download or read book Application of Chaos Methods to Helicopter Vibration Reduction Using Higher Harmonic Control written by Martinus M. Sarigul-Klijn and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chaos is a discipline used in understanding complex nonlinear dynamics. The geometric and topological methods of Chaos theory are applied, for the first time, to the study of flight test data. Data analyzed is from the McDonnell Douglas OH-6A Higher Harmonic Control (HHC) test aircraft. HHC is an active control system used to suppress helicopter vibrations. Some of the first practical applications of Chaos methods are demonstrated with the HHC data. Although helicopter vibrations are mostly periodic, evidence of chaos was found. The presenc3e of a strange attractor was shown by computing a positive Lyapunov exponent and computing a non-integer fractal correlation dimension. Also, a broad band Fourier spectrum and a well defined attractor in pseudo phase space are observed. A limit exists to HHC vibration reduction due to the presence of chaos. A new technique based on a relationship between the Chaos methods (the Poincare section and Van der Pol plane) and the vibration amplitude and phase was discovered. This newly introduced technique results in the following: 1) it gives the limits of HHC vibration reduction, 2) it allows rapid determination of best phase for a HHC controller, 3) it determines the minimum HHC controller requirement for any helicopter from a few minutes duration of flight test data (for the OH-6A, a scheduled gain controller for HHC appears to be adequate for steady level flight), 4) it shows that the HHC controller transfer matrix is linear and repeatable when the vibrations are defined in the?Rotor Time Domain? and that the matrix is nonlinear and nonrepeatable when the vibrations are defined in the?Clock Time Domain.? This technique will reduce future HHC flight test requirements. Further, the technique does not require the helicopter to be equipped with HHC. These methods may be applicable to other vibration control and flight testing problems.
Download or read book Engineering Flight Test of the Light Observation Helicopter LOH OH 6A Armed XM 27E1 and Unarmed Performance and Stability and Control written by William E Crouch (Jr) and published by . This book was released on 1967 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt:
