Small biological flyers and Micro Air Vehicles (MAVs) operate in a low Reynolds Number flight regime, close to the ground (within the atmospheric boundary layer), where the flow is known to be highly turbulent. Existing fixed-wing designs with conventional control surfaces mounted on the wings' trailing-edges, and actuated with commercially available servo actuators, have not been able to achieve sufficient control authority and rapidity to allow MAVs to fly straight and level in turbulent flow. Inspired by small biological flyers in this flight regime, that are known to utilize unsteady flow phenomena to produce significant control forces, the use of control surfaces hinged at the leading edge of the wing is investigated as a potential solution to improving MAV control response and authority. Two flat-plate airfoils, one with a leading-edge control surface and another with a trailing-edge control surface, were manufactured and tested in a wind tunnel. Dynamic forces were derived from surface pressure measurements at varying control surface deflections and actuation rates, at Reynolds number ranging from 40,000 to 160,000. Rapid actuation of either control surface revealed large transient forces, which could be exploited to compensate for the high-frequency perturbations MAVs encounter when flying in turbulence.
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