OPTIMAL EXCITATION FOR AIRCRAFT FLUTTER TESTING

The choice of excitation signal for flutter testing of a full-scale ai rcraft or wind tunnel model is crucial if the flutter test clearance i s to be performed quickly and with confidence. The use of chirps (that is, sinusoidal signals with varying frequency) is commonplace but has limitations. In this paper the idea of a simple chirp is extended to the development of a multi-sectional variable amplitude/variable power chirp in which the relative signal amplitude and power between sectio ns may be specified over the frequency range of interest. An optimal c hirp for a particular application may thus be designed. Sample results from a wind tunnel model flutter test are presented. In addition, the practice of sweeping up and then down infrequency is shown to be inad visable under certain circumstances.