Altshuler, Douglas L. and Dickson, William B. and Vance, Jason T. and Roberts, Stephen P. and Dickinson, Michael H. (2005) Short-amplitude high-frequency wing strokes determine the aerodynamics of honeybee flight. Proceedings of the National Academy of Sciences of the United States of America, 102 (50). pp. 18213-18218. ISSN 0027-8424 http://resolver.caltech.edu/CaltechAUTHORS:ALTpnas05
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Most insects are thought to fly by creating a leading-edge vortex that remains attached to the wing as it translates through a stroke. In the species examined so far, stroke amplitude is large, and most of the aerodynamic force is produced halfway through a stroke when translation velocities are highest. Here we demonstrate that honeybees use an alternative strategy, hovering with relatively low stroke amplitude (approximate to 90 degrees) and high wingbeat frequency (approximate to 230 Hz). When measured on a dynamically scaled robot, the kinematics of honeybee wings generate prominent force peaks during the beginning, middle, and end of each stroke, indicating the importance of additional unsteady mechanisms at stroke reversal. When challenged to fly in low-density heliox, bees responded by maintaining nearly constant wingbeat frequency while increasing stroke amplitude by nearly 50%. We examined the aerodynamic consequences of this change in wing motion by using artificial kinematic patterns in which amplitude was systematically increased in 5 degrees increments. To separate the aerodynamic effects of stroke velocity from those due to amplitude, we performed this analysis under both constant frequency and constant velocity conditions. The results indicate that unsteady forces during stroke reversal make a large contribution to net upward force during hovering but play a diminished role as the animal increases stroke amplitude and flight power. We suggest that the peculiar kinematics of bees may reflect either a specialization for increasing load capacity or a physiological limitation of their flight muscles.
|Additional Information:||Copyright © 2005 by the National Academy of Sciences. Edited by George N. Somero, Stanford University, Pacific Grove, CA and approved October 24, 2005 (received for review August 1, 2005). Published online before print December 5, 2005, 10.1073/pnas.0506590102. We thank David Shelton for the loan of equipment during filming. Funding was provided by National Institutes of Health Fellowship F32-NS46221 (to D.L.A.), National Science Foundation Grants IBN-0517635 (to S.P.R.) and IBN-0217229 (to M.H.D.), Office of Naval Research Grant N00014-03-1-0604 (to M.H.D.), and Packard Foundation Grant 2001-17741A (to M.H.D.).|
|Subject Keywords:||bee flight; flight in heliox; stroke amplitude; unsteady mechanisms; wingbeat kinematics|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||05 Jun 2006|
|Last Modified:||26 Dec 2012 08:47|
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