Meeting Abstract

21.5  Sunday, Jan. 4  Aerodynamic effects of wing flexibility in flapping flight ZHAO, Liang*; HUANG, Qingfeng; DENG, Xinyan; SANE, Sanjay; University of Delaware; University of Delaware; University of Delaware; National Centre for Biological Sciences, Tata Institute of Fundamental Research, India deng@udel.edu

Wings of insects are flexible structures. Although there has been much recent progress in the area of insect flight aerodynamics, very little is known about how wing flexibility influences aerodynamic forces during flapping flight. We investigated this question using a dynamically scaled mechanical model of insect wings. Using a suite of wings with varying flexural stiffness (EI) values, we generated aerodynamic polar plots to characterize the force coefficients of flexible wings. These polar plots showed that the aerodynamic performance of the wings varied with wing flexibility. In general, aerodynamic force production decreased with increasing flexibility. Both lift and drag coefficients of wings were greater when wings were more rigid. However, at very high angles of attack, flexible wings generated greater lift than a rigid wing. In addition, the ratio of lift-to-drag also decreased with increasing flexibility. In both rigid and flexible wings, the measured center of pressure showed little variation. These data show that flexible wings offer no aerodynamic advantage over a rigid wing under steady state circumstances. Because wing material in insects is usually flexible but reinforced by wing veins, we tested the hypothesis that wing veins enhance the aerodynamic performance of wings by increasing their effective stiffness. Our data suggests that even a very basic framework of appropriately placed wing veins can substantially increase the functional rigidity of the wings thereby enhancing its aerodynamic performance.