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Biol Lett. Jun 23, 2010; 6(3): 422–425.
Published online Feb 24, 2010. doi:  10.1098/rsbl.2010.0083
PMCID: PMC2880070
Within-wingbeat damping: dynamics of continuous free-flight yaw turns in Manduca sexta
Tyson L. Hedrick1* and Alice K. Robinson2
1Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
2California Institute of Technology, Division of Biology, Pasadena, CA, USA
*Author for correspondence (thedrick/at/
Received January 26, 2010; Accepted February 2, 2010.
Free-flight body dynamics and wing kinematics were collected from recordings of continuous, low-speed, multi-wingbeat yaw turns in hawkmoths (Manduca sexta) using stereo videography. These data were used to examine the effects of rotational damping arising from interactions between the body rotation and flapping motion (flapping counter-torque, FCT) on continuous turning. The moths were found to accelerate during downstroke, then decelerate during upstroke by an amount consistent with FCT damping. Wing kinematics related to turning were then analysed in a simulation of hawkmoth flight; results were consistent with the observed acceleration–deceleration pattern. However, an alternative wing kinematic which produced more continuous and less damped accelerations was found in the simulation. These findings demonstrate that (i) FCT damping is detectable in the dynamics of continuously turning animals and (ii) FCT-reducing kinematics do exist but were not employed by turning moths, possibly because within-wingbeat damping simplifies control of turning by allowing control systems to target angular velocity rather than acceleration.
Keywords: flight, control, dynamics, turning
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