Learning from bat: Aerodynamics of actively morphing wing

Abstract

Different from birds and insects, bats have complex wing-deformation capacity to generate high aerodynamic forces. In flight, the actively morphing of bat wing includes the twisting from wing root to wing tip, the cambering along the chordwise direction, the bending along the spanwise direction and the wing area-changing caused by the stretch and retraction of the wingspan. It was found that the high thrust and lift required in bat flight are dependent on the wing twisting and cambering respectively. Moreover, the integrated wing-morphing generates the aerodynamic lift and thrust mainly during the downstroke and almost negligible forces during the upstroke. The wing area-changing and bending can be used to amplify the positive forces in the downstroke duration and reduce the negative forces in the upstroke duration.