The harmonically oscillating wing with finite vortex trail

Abstract

The wing of infinite span oscillating harmonically in incompressible flow but having a vortex trail of finite length Sc is discussed theoretically. The 'incomplete circulation functions' Cs which arises in this case is tabulated. As an example, the damping moment due to slow pitching oscillations is shown for several values of S. The result is of interest as a wind-tunnel correction, in particular in that range of small frequencies which occurs in flight stability oscillations. Agreement with an experiment in an open-jet wind tunnel is obtained. A contradiction between different experiments in closed-jet wind tunnels is mentioned.