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Science 10 April 2009:
Vol. 324. no. 5924, pp. 252 - 255
DOI: 10.1126/science.1168431
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Reports

Wingbeat Time and the Scaling of Passive Rotational Damping in Flapping Flight

Tyson L. Hedrick,1* Bo Cheng,2 Xinyan Deng2*

Flying animals exhibit remarkable capabilities for both generating maneuvers and stabilizing their course and orientation after perturbation. Here we show that flapping fliers ranging in size from fruit flies to large birds benefit from substantial damping of angular velocity through a passive mechanism termed flapping counter-torque (FCT). Our FCT model predicts that isometrically scaled animals experience similar damping on a per-wingbeat time scale, resulting in similar turning dynamics in wingbeat time regardless of body size. The model also shows how animals may simultaneously specialize in both maneuverability and stability (at the cost of efficiency) and provides a framework for linking morphology, wing kinematics, maneuverability, and flight dynamics across a wide range of flying animals spanning insects, bats, and birds.

1 Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
2 Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA.

* To whom correspondence should be addressed. E-mail: thedrick{at}bio.unc.edu (T.L.H.); deng{at}udel.edu (X.D.)

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
STABILITY: JUST KEEP ON FLAPPING.
J. Usherwood (2009)
J. Exp. Biol. 212, iv
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Science. ISSN 0036-8075 (print), 1095-9203 (online)