Meeting Abstract
42.3 Tuesday, Jan. 5 Voluntary and perturbed free flight yaw maneuvers in hawkmoths HEDRICK, T.L.; ROBINSON, A.K.*; Univ. of North Carolina at Chapel Hill; California Institute of Technology thedrick@bio.unc.edu
A recent study of low speed maneuvering flight in animals ranging across 6 orders of magnitude in body size showed that animals engaged in low-speed yaw turns experience substantial damping of angular velocity (Hedrick et al., 2009). However, that prior study was not able to examine how this damping functions in practice in a free flying animal. Here we examined hawkmoths (Manduca sexta) engaged in continuous, voluntary, free-flight yaw maneuvers while tracking (but not feeding from) a nectar source. Flights were recorded using 3 calibrated high speed cameras and subjected to kinematic analysis. Maneuvers lasted up to 20 wingbeats and covered up to 270 degrees of total yaw, with peak whole-wingbeat yaw velocities up to 500 degrees s-1. These continuously turning moths only accelerated into the turn during downstroke; upstrokes were purely deceleratory. Upstroke deceleration was consistent with the damping through the flapping counter-torque (FCT) model put forth in Hedrick et al. (2009), with angular velocity dropping to approximately 65% of its initial value by the end of upstroke. In a separate set of recordings, hovering hawkmoths were subjected to physical perturbation sufficient to create yaw angular velocities of up to 1200 degrees s-1. Perturbed moths typically reduced their angular velocity in all axes to zero within 3 complete wingbeats; rapid deceleration began immediately at the end of perturbation. The first recovery wingbeat was consistent with a purely FCT deceleration, reducing angular velocity to approximately 48 percent of its initial value. Subsequent wingbeats from both station-keeping and escape moths did not fit the FCT deceleration profile; the moths appear to begin actively maneuvering from the second and subsequent wingbeats.
