Meeting Abstract

104.1  Tuesday, Jan. 7 08:00  The effect of aspect ratio on the generation of lift and drag of bat-like flapping wings SCHUNK, C.*; MICHAELSON, K.; PAINE, T.; SWARTZ, S. M.; BREUER, K. S.; Brown University; Brown University; Brown University; Brown University; Brown University cosima_schunk@brown.edu

Aspect ratio is frequently used to describe variation among the large diversity of bat wing shapes. Bats with high aspect ratio wings are expected to fly with high efficiency and to have superior lift-to-drag ratios. In contrast, bats with lower aspect ratio wings are thought to exhibit higher maneuverability. However, those assumptions often derive from theoretical models based on fixed wing aerodynamics. To examine the performance of highly compliant wings with different aspect ratios in flapping flight, we built several wings with different aspect ratios which, though simplified in shape, preserve many important features of bat wings such as a sharp leading edge of the propatagium, skeletal reinforcement of a compliant membrane and bat-relevant ratios of plagiopatagium to dactylopatagium. A two-degree-of-freedom shoulder joint allows for independent control of flapping amplitude and wing sweep to mimic the flapping motion of bats. We have measured the lift and drag forces generated by these bio-inspired mechanical wings flapping at frequencies that range from 2 to 10 Hz.