Wind-tunnel measurement of lateral aerodynamic derivatives using a new oscillatory rig, with results and comparisons for the GNAT aircraft

Abstract

The investigation of aircraft handling characteristics at high angle of attack and high subsonic speeds is hampered by the lack of accurate data on aerodynamic derivatives. The development of a rig and method of test for the measurement of oscillatory lateral aerodynamic derivatives under these conditions is described. Tests were made on a 0.16 scale model of a Gnat T Mk I aircraft and the results compared with those from wind-tunnel static tests, flight tests and estimates. Agreement with the other data is reasonably close except in the case of some cross damping derivatives. The accuracy of measurement of derivatives due to rate of roll should be improved by a proposed re-design of the excitation system.