Note on optimum propulsion of heaving and pitching airfoils from linear potential theory

What is it about?

Novel formulation for the thrust force of a pitching and heaving aerofoil is used to find out the conditions that maximize propulsive efficiency. For a pitching aerofoil the maximum propulsive efficiency is found when pivoting close to the three-quarter chord point from the leading edge with a relatively high reduced frequency, corresponding to a relatively low thrust coefficient. For a combined heaving and pitching motion, the peak propulsive efficiency predicted by this linear theory is for an aerofoil with a pitching axis close to, but ahead of, the three-quarter chord point, with a relatively large reduced frequency, a feathering parameter of approximately 0.9 and a phase shift slightly smaller than 90 degrees.

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