Ellington, Charles P. and Van Den Berg, Coen and Willmott, Alexander P. and Thomas, Adrian L. R. (1996) Leading-edge vortices in insect flight. Nature, 384 . pp. 626-630. ISSN 0028-0836
Full content URL: http://www.nature.com/nature/journal/v384/n6610/ab...
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|Item Status:||Live Archive|
INSECTS cannot fly, according to the conventional laws of aerodynamics: during flapping flight, their wings produce more lift than during steady motion at the same velocities and angles of attack1−5. Measured instantaneous lift forces also show qualitative and quantitative disagreement with the forces predicted by conventional aerodynamic theories6−9. The importance of high-life aerodynamic mechanisms is now widely recognized but, except for the specialized fling mechanism used by some insect species1,10−13, the source of extra lift remains unknown. We have now visualized the airflow around the wings of the hawkmoth Manduca sexta and a 'hovering' large mechanical model—the flapper. An intense leading-edge vortex was found on the down-stroke, of sufficient strength to explain the high-lift forces. The vortex is created by dynamic stall, and not by the rotational lift mechanisms that have been postulated for insect flight14−16. The vortex spirals out towards the wingtip with a spanwise velocity comparable to the flapping velocity. The three-dimensional flow is similar to the conical leading-edge vortex found on delta wings, with the spanwise flow stabilizing the vortex.
|Keywords:||leading-edge vortex, wings, aerodynamic mechanisms, airflow|
|Subjects:||H Engineering > H141 Fluid Mechanics|
C Biological Sciences > C340 Entomology
|Divisions:||College of Social Science > School of Sport and Exercise Science|
|Deposited On:||30 Oct 2010 22:24|
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