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Wake structure and wingbeat kinematics of a house-martin Delichon urbica

Rosén, Mikael LU ; Spedding, G. R. and Hedenström, Anders LU (2007) In Journal of the Royal Society Interface 4(15). p.659-668
Abstract
The wingbeat kinematics and wake structure of a trained house martin in free, steady flight in a wind tunnel have been studied over a range of flight speeds, and compared and contrasted with similar measurements for a thrush nightingale and a pair of robins. The house martin has a higher aspect ratio (more slender) wing, and is a more obviously agile and aerobatic flyer, catching insects on the wing. The wingbeat is notable for the presence at higher flight speeds of a characteristic pause in the upstroke. The essential characteristics of the wing motions can be reconstructed with a simple two-frequency model derived from Fourier analysis. At slow speeds, the distribution of wake vorticity is more simple than for the other previously... (More)
The wingbeat kinematics and wake structure of a trained house martin in free, steady flight in a wind tunnel have been studied over a range of flight speeds, and compared and contrasted with similar measurements for a thrush nightingale and a pair of robins. The house martin has a higher aspect ratio (more slender) wing, and is a more obviously agile and aerobatic flyer, catching insects on the wing. The wingbeat is notable for the presence at higher flight speeds of a characteristic pause in the upstroke. The essential characteristics of the wing motions can be reconstructed with a simple two-frequency model derived from Fourier analysis. At slow speeds, the distribution of wake vorticity is more simple than for the other previously measured birds, and the upstroke does not contribute to weight support. The upstroke becomes gradually more significant as the flight speed increases, and although the vortex wake shows a signature of the pause phase, the global circulation measurements are otherwise in good agreement with surprisingly simple aerodynamic models, and with predictions across the different species, implying quite similar aerodynamic performance of the wing sections. The local Reynolds numbers of the wing sections are sufficiently low that the well-known instabilities of attached laminar flows over lifting surfaces, which are known to occur at two to three times this value, may not develop. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Delichon urbica, image velocimetry, digital particle, wind tunnel, vortex wakes, bird flight, aerodynamics
in
Journal of the Royal Society Interface
volume
4
issue
15
pages
659 - 668
publisher
Royal Society
external identifiers
  • wos:000247907100007
  • scopus:34547624350
ISSN
1742-5662
DOI
10.1098/rsif.2007.0215
language
English
LU publication?
yes
id
e9ca4826-6af4-44f7-95be-211203732084 (old id 691835)
date added to LUP
2007-12-18 11:51:31
date last changed
2017-08-20 03:29:15
@article{e9ca4826-6af4-44f7-95be-211203732084,
  abstract     = {The wingbeat kinematics and wake structure of a trained house martin in free, steady flight in a wind tunnel have been studied over a range of flight speeds, and compared and contrasted with similar measurements for a thrush nightingale and a pair of robins. The house martin has a higher aspect ratio (more slender) wing, and is a more obviously agile and aerobatic flyer, catching insects on the wing. The wingbeat is notable for the presence at higher flight speeds of a characteristic pause in the upstroke. The essential characteristics of the wing motions can be reconstructed with a simple two-frequency model derived from Fourier analysis. At slow speeds, the distribution of wake vorticity is more simple than for the other previously measured birds, and the upstroke does not contribute to weight support. The upstroke becomes gradually more significant as the flight speed increases, and although the vortex wake shows a signature of the pause phase, the global circulation measurements are otherwise in good agreement with surprisingly simple aerodynamic models, and with predictions across the different species, implying quite similar aerodynamic performance of the wing sections. The local Reynolds numbers of the wing sections are sufficiently low that the well-known instabilities of attached laminar flows over lifting surfaces, which are known to occur at two to three times this value, may not develop.},
  author       = {Rosén, Mikael and Spedding, G. R. and Hedenström, Anders},
  issn         = {1742-5662},
  keyword      = {Delichon urbica,image velocimetry,digital particle,wind tunnel,vortex wakes,bird flight,aerodynamics},
  language     = {eng},
  number       = {15},
  pages        = {659--668},
  publisher    = {Royal Society},
  series       = {Journal of the Royal Society Interface},
  title        = {Wake structure and wingbeat kinematics of a house-martin Delichon urbica},
  url          = {http://dx.doi.org/10.1098/rsif.2007.0215},
  volume       = {4},
  year         = {2007},
}