Publication Date:
2004-12-14
Description:
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 60 degrees 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 (5 degrees to 10 degrees) 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Videler, J J -- Stamhuis, E J -- Povel, G D E -- New York, N.Y. -- Science. 2004 Dec 10;306(5703):1960-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Marine Biology (Experimental Marine Zoology Group), Groningen University, Post Office Box 14, 9750 AA, Haren, Netherlands. j.j.videler@biol.rug.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15591209" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Biomechanical Phenomena
;
Birds/anatomy & histology/*physiology
;
*Flight, Animal
;
Models, Anatomic
;
Wings, Animal/anatomy & histology/*physiology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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