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Proc Biol Sci. 2002 May 22;269(1495):1053-7.

How do birds' tails work? Delta-wing theory fails to predict tail shape during flight.

Author information

1
Department of Biological Sciences, University of Stirling, Stirling FK9 4LA, UK. mre2@stir.ac.uk

Abstract

Birds appear to use their tails during flight, but until recently the aerodynamic role that tails fulfil was largely unknown. In recent years delta-wing theory, devised to predict the aerodynamics of high-performance aircraft, has been applied to the tails of birds and has been successful in providing a model for the aerodynamics of a bird's tail. This theory now provides the conventional explanation for how birds' tails work. A delta-wing theory (slender-wing theory) has been used, as part of a variable-geometry model to predict how tail and wing shape should vary during flight at different airspeeds. We tested these predictions using barn swallows flying in a wind tunnel. We show that the predictions are not quantitatively well supported. This suggests that a new theory or a modified version of delta-wing theory is needed to adequately explain the way in which morphology varies during flight.

PMID:
12028763
PMCID:
PMC1690990
DOI:
10.1098/rspb.2001.1901
[Indexed for MEDLINE]
Free PMC Article

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