Thrust and Aerodynamic Forces from an Oscillating Leading Edge Flap

The article examines the thrust and aerodynamic forces from an oscillating leading edge flap. The classical analysis for the aerodynamic loads on an oscillating airfoil is extended to include the additional degree of freedom of a leading edge flap and its interaction with the standard plunge, pitch, and trailing edge flap motions. It is shown in the special case of an isolated leading edge flap that there exists for every hinge location a finite frequency to achieve a net thrust on the airfoil. Also, the minimum frequency to achieve a net thrust occurs for a leading edge flap of infinitesimal extent, in contrast to an oscillating trailing edge flap which achieves propulsion at lower frequencies when its length is maximized.