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Short-Amplitude High-Frequency Wing Strokes Determine the Aerodynamics of Honeybee Flight

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 hig...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2005-12, Vol.102 (50), p.18213-18218
Main Authors: Altshuler, Douglas L., Dickson, William B., Jason T. Vance, Roberts, Stephen P., Dickinson, Michael H.
Format: Article
Language:English
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Summary: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 ($\approx 90\textdegree$) and high wingbeat frequency ($\approx 230 Hz$). 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° 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.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0506590102