Flight Flutter Testing Methods And Techniques PDF Download

This paper presents a survey of excitation methods applied recently for flight flutter testing. Examples of excitation by frequency sweep, pseudo-random, harmonic oscillation and control feedback technique are given and their effectiveness and adaption to digital processing is discussed. Experience with generating aerodynamic forces by control-surfaces or additional vanes is presented. The second part of the paper deals with the digital analysis of flight flutter test data. Recommendations for selection of analysis parameters and how to avoid errors due to digital processing are given. For data evaluation in flight flutter tests the autopower-spectrum and transfer- and coherence function are used. Errors and effects of digital blockwise computation and analysis procedures like block overlapping, windowing, averaging or curve fitting are demonstrated. The filter correlation - and the modal analysis technique are applied for mode separation and damping evaluation based on the above mentioned functions. Practical experiences and examples from wind tunnel, flight and laboratory tests are discussed. In addition an on-line computer program is presented for realtime calculation of resonance frequencies and damping factors. (Author).