The role of wing shape in the aerodynamic performance of tiny insects*

The bristled wings of numerous species of tiny insects such as thrips and fairyflies show remarkable diversity in shape, ranging from short, teardrop-shaped to long, slender profiles. While wing area is well known to directly impact aerodynamic force generation, the effects of varying the ratio of leading edge to trailing edge wing area (LE/TE), as well as the ratio of wing span squared to wing area (AR), on the flapping flight of tiny insects are unknown. To examine the effect of wing shape, we fabricated 12 dynamically scaled wing models. Including three bristled and three solid models with AR of 3,5,7, four bristled models with LE/TE of 2, 1, 0.5, 0.25, and a thrips and fairyfly idealized replica model. These models were tested at Reynolds number = 10 on a 3D flapping robotic model to collect time varying lift and drag forces. We found that varying both LE/TE and AR had little effect on the cycle averaged lift and drag forces. Using 2D phase-locked particle image velocimetry on the LE/TE 2 and 0.25 wings, we found the strength of the leading-edge vortex was higher than that of the trailing-edge vortex during the downstroke for both wings. Flow field data will be presented on all the wings to further examine the aerodynamic effects of wing shape.