The Aerodynamics of Compliant Membrane Wings Modeled on Mammalian Flight Mechanics

Abstract

Mammalian flight is characterized by several features unique and distinct from the flight of both insects and birds. One such feature is the use of thin compliant wings as the lifting surface. Motivated by this, we present experimental results on the aerodynamics of compliant membrane wing models of low aspect ratio, performed at low Reynolds numbers, ranging from 30,000 to 100,000. Lift and Drag coefficients are measured over a range of angles of attack from -5 to 60 degrees. In addition the deformation of the wing due to aerodynamic loading is directly measured using a stereo photogrammetric method. Results indicate that the compliant wings' deformation increases with both angle of attack and that deformation scales with dynamic pressure until the onset of stall at which point inertial scaling fails. Stall on compliant wings occurs at higher angles of attack and is gentler than on a similar wing in which the membrane does not deform. Unsteady membrane vibrations are also measured and characterized.