Wavelet Analyses of F/A-18 Aeroelastic and Aeroservoelastic Flight Test Data

Wavelet Analyses of F/A-18 Aeroelastic and Aeroservoelastic Flight Test Data
Author: Martin J. Brenner
Publisher:
Total Pages: 28
Release: 1997
Genre: Aeroelasticity
ISBN:


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Time-frequency signal representations combined with subspace identification methods were used to analyze aeroelastic flight data from the F/A-18 Systems Research Aircraft (SRA) and aeroservoelastic data from the F/A-18 High Alpha Research Vehicle (HARV). The F/A-18 SRA data were produced from a wingtip excitation system that generated linear frequency chirps and logarithmic sweeps. HARV data were acquired from digital Schroeder-phased and sinc pulse excitation signals to actuator commands. Nondilated continuous Morlet wavelets implemented as a filter bank were chosen for the time-frequency analysis to eliminate phase distortion as it occurs with sliding window discrete Fourier transform techniques. Wavelet coefficients were filtered to reduce effects of noise and nonlinear distortions identically in all inputs and outputs. Cleaned reconstructed time domain signals were used to compute improved transfer functions. Time and frequency domain subspace identification methods were applied to enhanced reconstructed time domain data and improved transfer functions, respectively. Time domain subspace performed poorly, even with the enhanced data, compared with frequency domain techniques. A frequency domain subspace method is shown to produce better results with the data processed using the Morlet time-frequency technique.

Aeroservoelastic Model Validation and Test Data Analysis of the F/a-18 Active Aeroelastic Wing

Aeroservoelastic Model Validation and Test Data Analysis of the F/a-18 Active Aeroelastic Wing
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 36
Release: 2018-06-20
Genre:
ISBN: 9781721585212


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Model validation and flight test data analysis require careful consideration of the effects of uncertainty, noise, and nonlinearity. Uncertainty prevails in the data analysis techniques and results in a composite model uncertainty from unmodeled dynamics, assumptions and mechanics of the estimation procedures, noise, and nonlinearity. A fundamental requirement for reliable and robust model development is an attempt to account for each of these sources of error, in particular, for model validation, robust stability prediction, and flight control system development. This paper is concerned with data processing procedures for uncertainty reduction in model validation for stability estimation and nonlinear identification. F/A-18 Active Aeroelastic Wing (AAW) aircraft data is used to demonstrate signal representation effects on uncertain model development, stability estimation, and nonlinear identification. Data is decomposed using adaptive orthonormal best-basis and wavelet-basis signal decompositions for signal denoising into linear and nonlinear identification algorithms. Nonlinear identification from a wavelet-based Volterra kernel procedure is used to extract nonlinear dynamics from aeroelastic responses, and to assist model development and uncertainty reduction for model validation and stability prediction by removing a class of nonlinearity from the uncertainty. Brenner, Martin J. and Prazenica, Richard J. Armstrong Flight Research Center NASA/TM-2003-212021, H-2526, NAS 1.15:212021

Wavelet Analysis and Applications

Wavelet Analysis and Applications
Author: Tao Qian
Publisher: Springer Science & Business Media
Total Pages: 567
Release: 2007-02-24
Genre: Mathematics
ISBN: 376437778X


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This volume reflects the latest developments in the area of wavelet analysis and its applications. Since the cornerstone lecture of Yves Meyer presented at the ICM 1990 in Kyoto, to some extent, wavelet analysis has often been said to be mainly an applied area. However, a significant percentage of contributions now are connected to theoretical mathematical areas, and the concept of wavelets continuously stretches across various disciplines of mathematics. Key topics: Approximation and Fourier Analysis Construction of Wavelets and Frame Theory Fractal and Multifractal Theory Wavelets in Numerical Analysis Time-Frequency Analysis Adaptive Representation of Nonlinear and Non-stationary Signals Applications, particularly in image processing Through the broad spectrum, ranging from pure and applied mathematics to real applications, the book will be most useful for researchers, engineers and developers alike.

CEAS/AIAA/ICASE/NASA Langley International Forum on Aeroelasticity and Structural Dynamics 1999

CEAS/AIAA/ICASE/NASA Langley International Forum on Aeroelasticity and Structural Dynamics 1999
Author:
Publisher:
Total Pages: 460
Release: 1999
Genre: Aeroelasticity
ISBN:


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These proceedings represent a collection of the latest advances in aeroelasticity and structural dynamics from the world community. Research in the areas of unsteady aerodynamics and aeroelasticity, structural modeling and optimazation, active control and adaptive structures, landing dynamics, certification and qualification, and validation testing are highlighted in the collection of papers. The wide range of results will lead to advances in the prediction and control of the structural response of aircraft and spacecraft.

Flight Test of the F/A-18 Active Aeroelastic Wing Airplane

Flight Test of the F/A-18 Active Aeroelastic Wing Airplane
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
Total Pages: 44
Release: 2018-09-19
Genre: Science
ISBN: 9781723841774


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Successful flight-testing of the Active Aeroelastic Wing airplane was completed in March 2005. This program, which started in 1996, was a joint activity sponsored by NASA, Air Force Research Laboratory, and industry contractors. The test program contained two flight test phases conducted in early 2003 and early 2005. During the first phase of flight test, aerodynamic models and load models of the wing control surfaces and wing structure were developed. Design teams built new research control laws for the Active Aeroelastic Wing airplane using these flight-validated models; and throughout the final phase of flight test, these new control laws were demonstrated. The control laws were designed to optimize strategies for moving the wing control surfaces to maximize roll rates in the transonic and supersonic flight regimes. Control surface hinge moments and wing loads were constrained to remain within hydraulic and load limits. This paper describes briefly the flight control system architecture as well as the design approach used by Active Aeroelastic Wing project engineers to develop flight control system gains. Additionally, this paper presents flight test techniques and comparison between flight test results and predictions.Clarke, Robert and Allen, Michael J. and Dibley, Ryan P. and Gera, Joseph and Hodgkinson, JohnArmstrong Flight Research CenterAEROELASTICITY; FLIGHT CONTROL; FLIGHT TESTS; AEROELASTIC RESEARCH WINGS; AIRCRAFT CONTROL; FLIGHT CHARACTERISTICS; AIRCRAFT DESIGN; AERODYNAMIC CHARACTERISTICS; WING OSCILLATIONS