Flow visualization of butterfly aerodynamic mechanisms
Insect Flight Group, Oxford
Srygley, R. B. and A. L. R. Thomas (2002) Aerodynamics of insect flight: flow visualisations with free flying butterflies reveal a variety of unconventional lift-generating mechanisms. Nature 420: 660-664.
Flying insects generate forces that are too large to be accounted for by conventional steady-state aerodynamics. To investigate these mechanisms of force generation, we trained red admiral butterflies, Vanessa atalanta, to fly freely to and from artificial flowers in a windtunnel, and used high-resolution smoke-wire flow visualisations to obtain qualitative, high-speed digital images of the air flow around their wings. The images show that free-flying butterflies use a variety of unconventional aerodynamic mechanisms to generate force: wake capture, two different types of leading edge vortex, active and inactive upstrokes, in addition to the use of rotational mechanisms and the Weis-Fogh 'clap-and-fling' mechanism. Free flying butterflies often used different aerodynamic mechanisms in successive strokes. There seems to be no one 'key' to insect flight, instead insects rely on a wide array of aerodynamic mechanisms to take off, manoeuvre, maintain steady flight, and for landing.
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For additional information, refer to the News and Views article from Nature, and Kimberly Patch's report in Technology Research News online.
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Butterfly aerobatics, an interview which aired in March 2003 on New Zealand Public Radio: Eureka can be heard online.
Click for a quicktime movie (952 kbytes) of the red admiral butterfly Vanessa atalanta
See also our work on dragonfly flow visualization.
For additional information on insect flight biomechanics, check out the Animal Flight Group at the University of Oxford
or the websites of Michael Dickinson, Robert Dudley, Charlie Ellington, and Robin Wootton.
For additional information on micro aerial vehicles (MAVs), check out the Entomopter program at Georgia Tech.
Robert B. Srygley
Department of Zoology
University of Oxford
South Parks Road
Oxford OX1 3PS England
Email -- bob.srygley@ zoo.ox.ac.uk
Web -- http://users.ox.ac.uk/~zool0206/
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