Flight Flutter Test Techniques at ARL

Good design of an aircraft ensures that its flutter speed lies beyond its maximum operating speed; however, modification of the aircraft, such as the attachment of external stores to the wings, can lower the flutter speed significantly. In this case it may be necessary to determine experimentally the new flutter speed by means of a series of flight flutter trials. During such trails the aircraft is excited in flight and the measured response analysed to obtain estimates of the structural natural frequencies and damping ratios. This paper describes some of the methods which have been used in Australia to excite aircraft in flight flutter trials, together with the analytical techniques used to reduce the resulting data. Typical results from trials are presented. Keywords: Flutter, Flutter simulators, External stores, Aircraft design, Australia.