Comparative theoretical calculations of forces on oscillating wings through the transonic speed range

Abstract

Summary. Three planforms, rectangular, delta and symmetrical tapered, have been selected for combined theoretical and experimental aerodynamic research. Numerous linearized theoretical methods have been applied to each planform in oscillatory pitching and plunging motion at subsonic, sonic and supersonic Mach numbers. After a brief review of available theories, the calculated and measured data are presented. For each wing, separately, the lift and moment derivatives are studied as functions of Mach number, frequency parameter and pitching axis. It is found possible to link results from the various theories approximately by continous curves against Mach number for fixed values of the frequency parameter. Satisfactory comparisons with experiment are found in purely subsonic or supersonic flow, but in the transonic region uncertainties of tunnel-wall interference may mask the true discrepancies due to wing thickness and other non-linear disturbances. With the aid of exact or analytical theories for the particular wings, seven general theoretical methods have been appraised. Finally an attempt is made to review the status of linearized theory in the narrow transonic range where effects of frequency and Mach number become very large.