Calculating derivatives for rectangular wings oscillating in compressible subsonic flow

Abstract

Stability and flutter derivatives are obtained for rectangular wings describing plunging and pitching oscillations in subsonic flow. These are evaluated by applying the simple approximate 'equivalent' wing theory (R. & M. 2855) with the vortex-lattice method of downwash calculation. The derivatives for the wing of aspect ratio 4 at Mach number 0.866 are compared with values calculated by a method based on exact theory; at this high Mach number it is found that the present method is sufficiently accurate for only a very limited range of the frequency parameter. At very low values, the pitching-moment derivatives for this wing are in reasonable agreement with those calculated by the Multhopp-Garner method and with results from wind-tunnel tests at high subsonic Mach number.