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About 1,420 papers for “flutter testing”

Flutter Testing Techniques

nasa · 2016

Developments in methodology and data analysis techniques for flutter testing in flight and on the ground are discussed.

Cited by 9

Aircraft Flutter Testing

nasa · 2018

Wilmer Reed gained international recognition for his innovative research, contributions and patented ideas relating to flutter and aeroelasticity of aerospace vehicles at Langley Research Center. In the early 1980's, Reed retired from Langley and joined the engineering staff of Dynamic Engineering Inc. While at DEI, Reed conceived and patented the DEI Flutter Exciter, now used world-wide in flight flutter testing of new or modified aircraft designs. When activated, the DEI Flutter Exciter alternately deflects the airstream upward and downward in a rapid manner, creating a force similar to that produced by an oscillating trailing edge flap. The DEI Flutter Exciter is readily adaptable to a variety of aircraft.

Cited by 0

Flutter Testing Techniques

NASA Technical Reports Server (NASA)

Developments in methodology and data analysis techniques for flutter testing in flight and on the ground are discussed.

Cited by 0

Aircraft Flutter Testing

NASA STI Repository (National Aeronautics and Space Administration)

Wilmer Reed gained international recognition for his innovative research, contributions and patented ideas relating to flutter and aeroelasticity of aerospace vehicles at Langley Research Center. In the early 1980's, Reed retired from Langley and joined the engineering staff of Dynamic Engineering Inc. While at DEI, Reed conceived and patented the DEI Flutter Exciter, now used world-wide in flight flutter testing of new or modified aircraft designs. When activated, the DEI Flutter Exciter alternately deflects the airstream upward and downward in a rapid manner, creating a force similar to that produced by an oscillating trailing edge flap. The DEI Flutter Exciter is readily adaptable to a variety of aircraft.

Cited by 0Open access

Online Flight Flutter Testing

Grigorios Dimitriadis, Jonathan E. Cooper · Open Repository and Bibliography (University of Liège) · 2001

A number of different identification methods are considered as candidate approaches to undertake online flight flutter testing. Rather than flying the test aircraft to a new flight condition and then performing a data analysis at a constant flight condition, it is shown how it is feasible to track changes in frequencies and damping ratios as the flight speed is increased. It is also possible to provide an updated estimate of the predicted flutter speed, giving the flight engineers added confidence in the margin of safety. Both frequency and time domain methods are evaluated on a simulated 3 DOF aeroelastic system. These preliminary results show that such an approach is feasible although further work is required to determine the best testing and analysis approach.

Cited by 2

Flight Flutter Testing Symposium

NASA Technical Reports Server (NASA)

Papers presented at the conference are reported. Subjects discussed include: theory, methods and techniques, and flight flutter testing.

Cited by 0

Douglas Experience in Flight Flutter Testing

Jay Philbrick · NASA STI Repository (National Aeronautics and Space Administration) · 1975

Douglas Aircraft Company experience in flight flutter testing is reviewed briefly, with comments on state-of-the-art excitation and instrumentation techniques used up to the present time. The limitations of previous techniques are discussed with emphasis on the problem of: (1) establishing a flutter margin of safety for predicted marginal flutter modes; (2) resolving instances of flutter not predicted by theoretical calculations in advance; and (3) delaying the airplane demonstration by time consumed in acquisition and reduction of flutter data. Current Douglas philosophy in flight flutter testing is presented and a description given of steady-state vane excitation system development, automatic data handling system, and the potential application of automatic computing methods for increasing flutter data yield.

Cited by 1Open access

Flight flutter testing using pulse techniques

R. H. Stringham, Erik Lenk · NASA Technical Reports Server (NASA) · 1975

A case of flutter developed at a speed lower than had been flown previously. This incident precipitated the routine procedure of pulsing control surfaces as well as the firing of explosive charges during speed build-ups. In the interest of rapid evaluation of results, simple methods of data reduction were used. A case history is presented where in the pulse technique predicted flutter by extrapolating decay rates obtained at subcritical speeds; in addition, a case is presented where no valid extrapolation could be made.

Cited by 1

Flight Flutter Testing of the P6M

Goldman, R. L., Kachadourian, G., Roha, D. M. · NASA STI Repository (National Aeronautics and Space Administration)

On the P6M the shake behavior, i.e., the response to random excitation at subcritical speeds of lowly damped airplane modes, is as important as the actual flutter speed. The approach is to first study the problem by means of analyses and wind-tunnel tests. These predictions are compared with flight test data obtained by spectral analysis of tape recordings of the airplane vibration responses to random aerodynamic turbulence. A similar spectrum analysis approach was used in high speed wind-tunnel tests. A resonance excitation technique was developed for low speed wind-tunnel testing, and well defined V-g curves were obtained. The effect of various parameters on both shake and flutter of T-tails with and without dihedral were studied. Preliminary flight tests yielded good correlation; they also yielded interesting information concerning a low frequency transonic snaking mode, and excitation by shed vortices.

Cited by 0Open access

Experimental flutter testing of Prithvi models

AR Upadhya, Anant Joshi · Institutional Repository @ NAL (University of Southampton) · 1985

This is the Project proposal for the experimental flutter testing of Prithvi missile models.

Cited by 0Open access

Subcritical flutter testing and system identification

John C. Houbolt · NASA STI Repository (National Aeronautics and Space Administration) · 1974

Treatment is given of system response evaluation, especially in application to subcritical flight and wind tunnel flutter testing of aircraft. An evaluation is made of various existing techniques, in conjuction with a companion survey which reports theoretical and analog experiments made to study the identification of system response characteristics. Various input excitations are considered, and new techniques for analyzing response are explored, particularly in reference to the prevalent practical case where unwanted input noise is present, such as caused by gusts or wind tunnel turbulence. Further developments are also made of system parameter identification techniques.

Cited by 8Open access

Flight flutter testing using pulse techniques

Lenk, E. J., Stringham, R. H., Jr. · NASA STI Repository (National Aeronautics and Space Administration)

A case of flutter developed at a speed lower than had been flown previously. This incident precipitated the routine procedure of pulsing control surfaces as well as the firing of explosive charges during speed build-ups. In the interest of rapid evaluation of results, simple methods of data reduction were used. A case history is presented where in the pulse technique predicted flutter by extrapolating decay rates obtained at subcritical speeds; in addition, a case is presented where no valid extrapolation could be made.

Cited by 0Open access

Flight flutter testing technology at Grumman

Milordi, F. W., Perangelo, H. J. · NASA STI Repository (National Aeronautics and Space Administration)

Analysis techniques used in the automated telemetry station (ATS) for on line data reduction are encompassed in a broad range of software programs. Concepts that form the basis for the algorithms used are mathematically described. The control the user has in interfacing with various on line programs is discussed. The various programs are applied to an analysis of flight data which includes unimodal and bimodal response signals excited via a swept frequency shaker and/or random aerodynamic forces. A nonlinear response error modeling analysis approach is described. Preliminary results in the analysis of a hard spring nonlinear resonant system are also included.

Cited by 0Open access

Model mount system for testing flutter

Farmer, M. G. · NASA Technical Reports Server (NASA)

A wind tunnel model mount system is disclosed for effectively and accurately determining the effects of attack and airstream velocity on a model airfoil or aircraft. The model mount system includes a rigid model attached to a splitter plate which is supported away from the wind tunnel wall several of flexible rods. Conventional instrumentation is employed to effect model rotation through a turntable and to record model flutter data as a function of the angle of attack versus dynamic pressure.

Cited by 0Open access

Wavelet Applications for Flight Flutter Testing

Freudinger, Lawrence C., Lind, Rick, Brenner, Marty · NASA Technical Reports Server (NASA)

Wavelets present a method for signal processing that may be useful for analyzing responses of dynamical systems. This paper describes several wavelet-based tools that have been developed to improve the efficiency of flight flutter testing. One of the tools uses correlation filtering to identify properties of several modes throughout a flight test for envelope expansion. Another tool uses features in time-frequency representations of responses to characterize nonlinearities in the system dynamics. A third tool uses modulus and phase information from a wavelet transform to estimate modal parameters that can be used to update a linear model and reduce conservatism in robust stability margins.

Cited by 0Open access

SEVERAL TECHIQUES FOR FLIGHT FLUTTER TESTING

Defense Technical Information Center (DTIC) · 1960

There are two techniques currently in use for investigating the flutter characteristics of an aircraft by studying the response of the aircraft to a sinusoidal force input. They are the amplitude response technique and the vectorialANALYSIS TECHNIQUE. Electrodynamic vibrators were utilized for in flight measurement of the response of an aircraft wing to harmonic excitation. Other factors considered for flight flutter testing were structural dynamics, basic excitation, simple harmonic excitation, pulse excitation, airborne instrumentation, data system and analysis, and flight test techniques. (Author)

Cited by 0