During the last decades the use of micro-air vehicles (MAV) in intelligence, surveillance, and reconnaissance missions has grown significantly. These missions require the MAVs to present high maneuvering skills while flying at relatively low velocities (around 10 m/s), thus making their aerodynamic design highly challenging due to the low-Reynolds flow and their sensitivity to atmospheric turbulence (gusts). Low-Reynolds natural flyers with similar dimensions, such as bats, often use membrane wings. These are thin, elastic wings that adapt their shape to the flow conditions. Membrane wings are now implemented in MAVs as well, with an attempt to mimic nature. The current research focuses on the response of an elastic membrane wing to unsteady flow conditions, and in particular to gusts.
Membrane wings are unique in their ability to deform during flight. The membrane shape is determined by an equilibrium of forces between the aerodynamic load, the inertial forces, and the tension along the membrane. The current research is aimed at studying the membrane wing dynamic response to gusts at low Reynolds numbers. This is obtained by three research phases: first, the membrane dynamic response to initial conditions is studied analytically for potential flow, presenting a stability map for the membrane in terms of the tension and membrane mass. Then, the membrane dynamic response to initial conditions is studied computationally for low-Reynolds flow. Finally, the gust response of a rigid thin airfoil is studied in low-Reynolds flow. The combination of these three parts provide insight on the functionality of membrane wings in gusty environment.
