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Investigation Of Vibration Reduction Techniques For The Boeing Ch 47 Chinook Helicopter
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Book Synopsis Investigation of Vibration Reduction Techniques for the Boeing CH-47 Chinook Helicopter by : Allen Randolph Wells
Download or read book Investigation of Vibration Reduction Techniques for the Boeing CH-47 Chinook Helicopter written by Allen Randolph Wells and published by . This book was released on 2001 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experiences at Langley Research Center in the Application of Optimization Techniques to Helicopter Airframes for Vibration Reduction by :
Download or read book Experiences at Langley Research Center in the Application of Optimization Techniques to Helicopter Airframes for Vibration Reduction written by and published by . This book was released on 1991 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter transmission vibration and noise reduction program by :
Download or read book Helicopter transmission vibration and noise reduction program written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Shock and Vibration Bulletin by :
Download or read book The Shock and Vibration Bulletin written by and published by . This book was released on 1973 with total page 930 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Investigation of Helicopter Transmission Noise Reduction by Vibration Absorbers and Damping by : H. Sternfeld
Download or read book An Investigation of Helicopter Transmission Noise Reduction by Vibration Absorbers and Damping written by H. Sternfeld and published by . This book was released on 1972 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Department of the army by : United States. Congress. Senate. Committee on Appropriations
Download or read book Department of the army written by United States. Congress. Senate. Committee on Appropriations and published by . This book was released on 1971 with total page 1562 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Vibration Reduction Through Structural Optimization by : Horace W. Hanson
Download or read book Investigation of Vibration Reduction Through Structural Optimization written by Horace W. Hanson and published by . This book was released on 1980 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this program was to investigate structural optimization techniques for vibration reduction. The results of a practical evaluation of two such techniques, the Vincent circle method and the forced response strain energy method, are discussed. Initial comparison studies of the two methods based on stiffness parameter variations were conducted using an elastic-line NASTRAN model of the AH-1G helicopter. The forced response strain energy method was then applied to a large complex built-up NASTRAN AH-1G model. This application provided useful comparative data identifying the structural elements considered to be the primary contributors to the response. Realistic structural stiffness changes in these elements were assessed to determine their effect on vibration reduction. The Vincent circle method was further evaluated for mass tuning, damping, and dynamic absorber parameters using the elastic-line model. (Author).
Book Synopsis Application of Chaos Methods to Helicopter Vibration Reduction Using Higher Harmonic Control by : Martinus M. Sarigul-Klijn
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.
Book Synopsis The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) Program: A Government Overview by :
Download or read book The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) Program: A Government Overview written by and published by . This book was released on 1992 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Application of Chaos Methods to Helicopter Vibration Reduction Using Higher Harmonic Control by : Martinus M. Sarigul-Klijn
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.
Book Synopsis Advanced Control Techniques for Control of Rotorcraft Vibration by :
Download or read book Advanced Control Techniques for Control of Rotorcraft Vibration written by and published by . This book was released on 2003 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this project is to develop vibration and control approaches and software suitable for use in the flight tests of the MD-900 helicopter, and to assist Boeing in the preparations for flight test, to enable them to use our advanced control approaches. During this effort, we have studied the feasibility of improving the robustness of X-frame actuator systems using feedback control approaches. We have investigated various feedback control design techniques to find out whether it is feasible to make the actuator robust without sacrificing its performance, and concluded that the flap position control may not be required, and even more, may be counter-productive. We have also improved the system identification methodology to investigate periodic effects, and applied it to the flight test data at Langley. Our analysis of the Langley data shows that periodic effects are negligible, so that periodic control methods are probably not required for vibration control of active rotors. Finally, we have evaluated our advanced continuous-time control system approach to reduce the helicopter vibration using wind tunnel test data at Langley, and found that our approach yields more than 20 dB of vibration reduction at the frequency components of interest.
Book Synopsis An Investigation Into the Feasibility of Retrospectively Fitting a Vibration Reduction System to the GKN Westland Lynx Helicopter by : K. W. Thompson
Download or read book An Investigation Into the Feasibility of Retrospectively Fitting a Vibration Reduction System to the GKN Westland Lynx Helicopter written by K. W. Thompson and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Senstitivty Analysis and Optimization of Nodal Point Placement for Vibration Reduction by :
Download or read book Senstitivty Analysis and Optimization of Nodal Point Placement for Vibration Reduction written by and published by . This book was released on 1986 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Application of a LISP Based Expert System for Failure Diagnosis of the CH-47 Flight Control Hydraulic System by : Christopher J. Loh
Download or read book An Application of a LISP Based Expert System for Failure Diagnosis of the CH-47 Flight Control Hydraulic System written by Christopher J. Loh and published by . This book was released on 1986 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the hydraulic flight control system of a Boeing CH-47 Chinook helicopter utilizing artificial intelligence techniques will be undertaken. Specifically, a knowledge based expert system will employ situation-action rules (production rules) to diagnose a failure and subsequently identify specific devices(s) which caused that failure. Moreover, because the behavior of the system is directly responsive to the goals the system is attempting to achieve, the expert system's inference engine performs a backward-chaining process via a goal-driven control strategy. The List Processing Language (LISP) is used to facilitate data processing and symbolic logic expression.
Book Synopsis A Prototype Maintenance Expert System for the CH-47 Flight Control Hydraulic System by : Christopher J. Loh
Download or read book A Prototype Maintenance Expert System for the CH-47 Flight Control Hydraulic System written by Christopher J. Loh and published by . This book was released on 1986 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the hydraulic flight control system of a Boeing CH-47 Chinook helicopter using artificial intelligence techniques will be undertaken. Specifically, a knowledge based expert system will employ situation-action rules (production rules) to diagnose a failure and subsequently identify specific device(s) which caused that failure. Moreover, because the behavior of the system is directly responsive to the goals the system is directly attempting to achieve, the expert system's inference engine performs a backward-chaining process via a goal-driven control strategy. This strategy involves finding rules that demonstrate the hypothesis and then verifying the facts that enable the rule to work. The List Processing Language (LIPS) is used to facilitate data processing and symbolic logic expression manipulation. Keyword: Diagnostics.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781723145964 Total Pages :138 pages Book Rating :4.1/5 (459 download)
Book Synopsis Higher Harmonic Control Analysis for Vibration Reduction of Helicopter Rotor Systems by : National Aeronautics and Space Administration (NASA)
Download or read book Higher Harmonic Control Analysis for Vibration Reduction of Helicopter Rotor Systems written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced higher harmonic control (HHC) analysis has been developed and applied to investigate its effect on vibration reduction levels, blade and control system fatigue loads, rotor performance, and power requirements of servo-actuators. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model, based on the indicial response formulation, is used to calculate the airloads. The rotor induced inflow is computed using a free wake model. The vehicle trim controls and blade steady responses are solved as one coupled solution using a modified Newton method. A linear frequency-domain quasi-steady transfer matrix is used to relate the harmonics of the vibratory hub loads to the harmonics of the HHC inputs. Optimal HHC is calculated from the minimization of the vibratory hub loads expressed in term of a quadratic performance index. Predicted vibratory hub shears are correlated with wind tunnel data. The fixed-gain HHC controller suppresses completely the vibratory hub shears for most of steady or quasi-steady flight conditions. HHC actuator amplitudes and power increase significantly at high forward speeds (above 100 knots). Due to the applied HHC, the blade torsional stresses and control loads are increased substantially. For flight conditions where the blades are stalled considerably, the HHC input-output model is quite nonlinear. For such cases, the adaptive-gain controller is effective in suppressing vibratory hub loads, even though HHC may actually increase stall areas on the rotor disk. The fixed-gain controller performs poorly for such flight conditions. Comparison study of different rotor systems indicates that a soft-inplane hingeless rotor requires less actuator power at high speeds (above 130 knots) than an articulated rotor, and a stiff-inplane hingeless rotor generally requires more actuator power than an articulated or a soft-inplane hingeless rotor. Parametric studies for a hingeless rotor operati...
Book Synopsis Adaptive Inverse Control for Helicopter Vibration Reduction by :
Download or read book Adaptive Inverse Control for Helicopter Vibration Reduction written by and published by . This book was released on 1983 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
