Unusual aero--flapping and pumping

[khafra]

Score! Open-loop and closed-loop excitation of the wake behind a circular cylinder The flapping spoilers should have a frequency twice that of the vortex shedding frequency, which is simply fd/V = 0.198(1-19.7/Re) where f is the frequency, d is the bluff body's diameter, V is the flow velocity, and Re is the Reynolds number of the flow. Get some speedometer input, do some simple arithmetic, and you're there.