Meeting Abstract

59.1  Saturday, Jan. 5  Wing bending is modulated during flight and affects the induced flow field of Manduca sexta. MOUNTCASTLE, A.M.*; DANIEL, T.L.; Univ.Washington, Seattle; Univ.Washington, Seattle danielt@u.washington.edu

Most computational and physical models of insect flight assume that wings are rigid. However, many insect wings flex passively during flight. Large wing deformations occur in the hawkmoth Manduca sexta,peaking at ventral stroke reversal, and predominantly appearing as bending waves traveling chordwise in less than 10 ms. Prior theoretical analysis suggests that this rapidly-propagating wave may contribute significant aerodynamic forces to flight. Here, we ask: 1) to what extent are bending wing waves modulated within an individual during hovering flight? and 2) to what degree does the flow field reflect the contributions of wing deformation? We used high-speed digital videography to quantify 3D wing kinematics of hovering hawkmoths. Our results show stroke-to-stroke variation in bending waves, suggesting a potential mechanism for control of flight forces. Recent neural evidence showing rapid and precise sensory encoding of wing strain further supports a control role for bending. However, there is scant experimental evidence that flexibility affects the flow field around a flapping wing. To explore flow fields around wings of varying stiffness, we robotically oscillated detached wings at their natural wing beat frequency (25 Hz.). Wing flexural stiffness increased as isolated wings were allowed to dry..We used DPIV to characterize the wake patterns around oscillated wings by quantifying spatial and temporal patterns of the distribution of vorticity and velocity. The magnitude, timing, and location of peak vorticity was related to the wing stiffness. Totether with prior theoretical and neurobiological work, our data suggest that the bending dynamics of wings may play an important role in the control of flight.