Leading-Edge Vortex lifts swifts

J. J. Videler, E. J. Stamhuis, G. D. E. Povel

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123 Citations (Scopus)

Abstract

The current understanding of how birds fly must be revised, because birds use their hand-wings in an unconventional way to generate lift and drag. Physical models of a common swift wing in gliding posture with a 60degrees sweep of the sharp hand-wing leading edge were tested in a water tunnel. Interactions with the flow were measured quantitatively with digital particle image velocimetry at Reynolds numbers realistic for the gliding flight of a swift between 3750 and 37,500. The results show that gliding swifts can generate stable leading-edge vortices at small (5degrees to 10degrees) angles of attack. We suggest that the flow around the arm-wings of most birds can remain conventionally attached, whereas the swept-back hand-wings generate lift with leading-edge vortices.

Original languageEnglish
Pages (from-to)1960-1962
Number of pages3
JournalScience
Volume306
Issue number5703
DOIs
Publication statusPublished - 10-Dec-2004

Keywords

  • PARTICLE IMAGE VELOCIMETRY
  • INSECT FLIGHT
  • WIND-TUNNEL
  • SPEEDS

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