Bioinspired corrugated airfoils for micro air vehicles

Dragonflies exhibit glide and flapping flight modes using wings composed of corrugated flat plates. It has previously been shown that corrugated airfoils exhibit superior lift-to-drag ratios over conventional airfoils at Reynolds numbers of 8,000. The literature also shows a significant sensitivity of aerodynamic performance with Reynolds number and flight condition. These sensitivities may mean that the corrugations are a compromise between structural and aerodynamic characteristics due to their stiffening effect. We consider the effect at a higher Reynolds number of 34,000 which is close to where our unmanned aircraft with a conventional airfoil currently operates. We compare the aerodynamics of a corrugated geometry, with a flat plate and a conventional low Reynolds number airfoil. The results confirm that surface corrugation of the baseline shape has limited aerodynamic efficiency at low angles-of-attack relative to the flat plate and the Eppler E61 profile. Avenues for further design analysis with eventual focus on shape optimisation is needed to confirm the role of corrugation in sustaining efficient flight modes at an even lower Re and across an extended angle of attack test range.