Technique for flutter tests using ground-launched rockets, with results for unswept wings

Abstract

A technique for the investigation of wing flutter by means of ground-launched rockets is described. An important feature of the technique is that it can be used at high speeds, including the transonic range. Model wings are attached to a solid-fuel rocket which has a miniature telemetry set housed in a detachable nose fairing. A vibration pick-up and break wires are fitted in the flutter model and these modulate the output of the telemetry set to transmit flutter information to a ground station. The rocket is fired over an open artillery range and its velocity-time curve is obtained by radio reflection Doppler equipment. Results are given of tests on flutter models of unswept, untapered wings in the range of Mach number from 0.4 to 1.0. The effects of longitudinal acceleration on the flutter are shown to be negligible for the range of acceleration and Mach number investigated, and the effect of compressibility is to reduce the margin of the measured speed above the speed calculated on the basis of incompressible flow theory from + 50 per cent at M = 0.4 to - 25 per cent at M = 0.9. A wing torsional stiffness criterion is shown to give a fair approximation to the test results.