Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus)
(2016) In Scientific Reports 6.- Abstract
Large ears enhance perception of echolocation and prey generated sounds in bats. However, external ears likely impair aerodynamic performance of bats compared to birds. But large ears may generate lift on their own, mitigating the negative effects. We studied flying brown long-eared bats, using high resolution, time resolved particle image velocimetry, to determine the aerodynamics of flying with large ears. We show that the ears and body generate lift at medium to cruising speeds (3-5 m/s), but at the cost of an interaction with the wing root vortices, likely reducing inner wing performance. We also propose that the bats use a novel wing pitch mechanism at the end of the upstroke generating thrust at low speeds, which should provide... (More)
Large ears enhance perception of echolocation and prey generated sounds in bats. However, external ears likely impair aerodynamic performance of bats compared to birds. But large ears may generate lift on their own, mitigating the negative effects. We studied flying brown long-eared bats, using high resolution, time resolved particle image velocimetry, to determine the aerodynamics of flying with large ears. We show that the ears and body generate lift at medium to cruising speeds (3-5 m/s), but at the cost of an interaction with the wing root vortices, likely reducing inner wing performance. We also propose that the bats use a novel wing pitch mechanism at the end of the upstroke generating thrust at low speeds, which should provide effective pitch and yaw control. In addition, the wing tip vortices show a distinct spiraling pattern. The tip vortex of the previous wingbeat remains into the next wingbeat and rotates together with a newly formed tip vortex. Several smaller vortices, related to changes in circulation around the wing also spiral the tip vortex. Our results thus show a new level of complexity in bat wakes and suggest large eared bats are less aerodynamically limited than previous wake studies have suggested.
(Less)
- author
- Johansson, Christoffer LU ; Håkansson, Jonas LU ; Jakobsen, Lasse and Hedenström, Anders LU
- organization
- publishing date
- 2016-04-27
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Scientific Reports
- volume
- 6
- article number
- 24886
- publisher
- Nature Publishing Group
- external identifiers
-
- pmid:27118083
- wos:000374906600001
- scopus:84964589356
- ISSN
- 2045-2322
- DOI
- 10.1038/srep24886
- language
- English
- LU publication?
- yes
- id
- 042e49b0-dc8e-468f-bb03-e10f8ba3ad3c
- date added to LUP
- 2016-07-26 09:52:17
- date last changed
- 2024-03-22 05:44:13
@article{042e49b0-dc8e-468f-bb03-e10f8ba3ad3c,
abstract = {{<p>Large ears enhance perception of echolocation and prey generated sounds in bats. However, external ears likely impair aerodynamic performance of bats compared to birds. But large ears may generate lift on their own, mitigating the negative effects. We studied flying brown long-eared bats, using high resolution, time resolved particle image velocimetry, to determine the aerodynamics of flying with large ears. We show that the ears and body generate lift at medium to cruising speeds (3-5 m/s), but at the cost of an interaction with the wing root vortices, likely reducing inner wing performance. We also propose that the bats use a novel wing pitch mechanism at the end of the upstroke generating thrust at low speeds, which should provide effective pitch and yaw control. In addition, the wing tip vortices show a distinct spiraling pattern. The tip vortex of the previous wingbeat remains into the next wingbeat and rotates together with a newly formed tip vortex. Several smaller vortices, related to changes in circulation around the wing also spiral the tip vortex. Our results thus show a new level of complexity in bat wakes and suggest large eared bats are less aerodynamically limited than previous wake studies have suggested.</p>}},
author = {{Johansson, Christoffer and Håkansson, Jonas and Jakobsen, Lasse and Hedenström, Anders}},
issn = {{2045-2322}},
language = {{eng}},
month = {{04}},
publisher = {{Nature Publishing Group}},
series = {{Scientific Reports}},
title = {{Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus)}},
url = {{http://dx.doi.org/10.1038/srep24886}},
doi = {{10.1038/srep24886}},
volume = {{6}},
year = {{2016}},
}