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Downstroke and upstroke conflict during banked turns in butterflies

Henningsson, P. LU and Johansson, L. C. LU (2021) In Journal of the Royal Society, Interface 18(185). p.20210779-20210779
Abstract

For all flyers, aeroplanes or animals, making banked turns involve a rolling motion which, due to higher induced drag on the outer than the inner wing, results in a yawing torque opposite to the turn. This adverse yaw torque can be counteracted using a tail, but how animals that lack tail, e.g. all insects, handle this problem is not fully understood. Here, we quantify the performance of turning take-off flights in butterflies and find that they use force vectoring during banked turns without fully compensating for adverse yaw. This lowers their turning performance, increasing turn radius, since thrust becomes misaligned with the flight path. The separation of function between downstroke (lift production) and upstroke (thrust... (More)

For all flyers, aeroplanes or animals, making banked turns involve a rolling motion which, due to higher induced drag on the outer than the inner wing, results in a yawing torque opposite to the turn. This adverse yaw torque can be counteracted using a tail, but how animals that lack tail, e.g. all insects, handle this problem is not fully understood. Here, we quantify the performance of turning take-off flights in butterflies and find that they use force vectoring during banked turns without fully compensating for adverse yaw. This lowers their turning performance, increasing turn radius, since thrust becomes misaligned with the flight path. The separation of function between downstroke (lift production) and upstroke (thrust production) in our butterflies, in combination with a more pronounced adverse yaw during the upstroke increases the misalignment of the thrust. This may be a cost the butterflies pay for the efficient thrust-generating upstroke clap, but also other insects fail to rectify adverse yaw during escape manoeuvres, suggesting a general feature in functionally two-winged insect flight. When lacking tail and left with costly approaches to counteract adverse yaw, costs of flying with adverse yaw may be outweighed by the benefits of maintaining thrust and flight speed.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
aerodynamics, butterflies, flight, manoeuvring
in
Journal of the Royal Society, Interface
volume
18
issue
185
pages
1 pages
publisher
The Royal Society of Canada
external identifiers
  • scopus:85122468664
  • pmid:34847788
ISSN
1742-5662
DOI
10.1098/rsif.2021.0779
language
English
LU publication?
yes
id
c163a8af-3bb0-4250-8fe7-8d19fb93b033
date added to LUP
2022-02-06 12:59:04
date last changed
2024-06-09 02:23:10
@article{c163a8af-3bb0-4250-8fe7-8d19fb93b033,
  abstract     = {{<p>For all flyers, aeroplanes or animals, making banked turns involve a rolling motion which, due to higher induced drag on the outer than the inner wing, results in a yawing torque opposite to the turn. This adverse yaw torque can be counteracted using a tail, but how animals that lack tail, e.g. all insects, handle this problem is not fully understood. Here, we quantify the performance of turning take-off flights in butterflies and find that they use force vectoring during banked turns without fully compensating for adverse yaw. This lowers their turning performance, increasing turn radius, since thrust becomes misaligned with the flight path. The separation of function between downstroke (lift production) and upstroke (thrust production) in our butterflies, in combination with a more pronounced adverse yaw during the upstroke increases the misalignment of the thrust. This may be a cost the butterflies pay for the efficient thrust-generating upstroke clap, but also other insects fail to rectify adverse yaw during escape manoeuvres, suggesting a general feature in functionally two-winged insect flight. When lacking tail and left with costly approaches to counteract adverse yaw, costs of flying with adverse yaw may be outweighed by the benefits of maintaining thrust and flight speed.</p>}},
  author       = {{Henningsson, P. and Johansson, L. C.}},
  issn         = {{1742-5662}},
  keywords     = {{aerodynamics; butterflies; flight; manoeuvring}},
  language     = {{eng}},
  month        = {{12}},
  number       = {{185}},
  pages        = {{20210779--20210779}},
  publisher    = {{The Royal Society of Canada}},
  series       = {{Journal of the Royal Society, Interface}},
  title        = {{Downstroke and upstroke conflict during banked turns in butterflies}},
  url          = {{http://dx.doi.org/10.1098/rsif.2021.0779}},
  doi          = {{10.1098/rsif.2021.0779}},
  volume       = {{18}},
  year         = {{2021}},
}