Meeting Abstract

9.3  Tuesday, Jan. 4  Pitch perturbation recovery in free-flying hawkmoths GREETER, JSM*; HEDRICK, TL; Univ. of North Carolina at Chapel Hill jgreeter@email.unc.edu

The ability of flying animals to recover rapidly from apparently massive perturbations has long fascinated observers ranging from frolicking cats to jet-pilots. Recent animal flight studies highlighted the importance of passive mechanisms in yaw dynamics but left other directions unexplored. We examined perturbation recovery in the hawkmoth Manduca sexta, assessing the importance of passive and active responses as well as the magnitude of perturbation from which moths can recover. These perturbations were induced in free-flying moths by striking them from below in mid-air with a projectile fired by a spring-loaded cannon. This typically resulted in a primarily pitch up or pitch down movement in the moth. We then used high-speed videography and 3D reconstruction to measure angular and translational kinematics of the animals following impact. The moths typically restored their original pitch angle within a few wingbeats. Moths that failed to recover their original pitch angle often regained zero pitch velocity even if they crashed. We further characterized the perturbation responses by fitting damped oscillation curves to the observed pitch velocities. The resulting decay rates were substantially greater than those predicted by a blade-element simulation of pitch-perturbed moths with constant flapping kinematics. This suggests that both passive damping and an active response are present in the first wingbeats following perturbation or, alternatively, that the passive response is much greater than indicated by the simplified model. The time to recovery from perturbation appears that it might vary with the wingbeat cycle phase in which impact occurs, indicating that mean-wingbeat models of animal flight dynamics may not be adequate to describe the performance of these moths.