Butterflies fly using efficient propulsive clap mechanism owing to flexible wings
(2021) In Journal of the Royal Society, Interface 18(174).- Abstract
Butterflies look like no other flying animal, with unusually short, broad and large wings relative to their body size. Previous studies have suggested butterflies use several unsteady aerodynamic mechanisms to boost force production with upstroke wing clap being a prominent feature. When the wings clap together at the end of upstroke the air between the wings is pressed out, creating a jet, pushing the animal in the opposite direction. Although viewed, for the last 50 years, as a crucial mechanism in insect flight, quantitative aerodynamic measurements of the clap in freely flying animals are lacking. Using quantitative flow measurements behind freely flying butterflies during take-off and a mechanical clapper, we provide aerodynamic... (More)
Butterflies look like no other flying animal, with unusually short, broad and large wings relative to their body size. Previous studies have suggested butterflies use several unsteady aerodynamic mechanisms to boost force production with upstroke wing clap being a prominent feature. When the wings clap together at the end of upstroke the air between the wings is pressed out, creating a jet, pushing the animal in the opposite direction. Although viewed, for the last 50 years, as a crucial mechanism in insect flight, quantitative aerodynamic measurements of the clap in freely flying animals are lacking. Using quantitative flow measurements behind freely flying butterflies during take-off and a mechanical clapper, we provide aerodynamic performance estimates for the wing clap. We show that flexible butterfly wings, forming a cupped shape during the upstroke and clap, thrust the butterfly forwards, while the downstroke is used for weight support. We further show that flexible wings dramatically increase the useful impulse (+22%) and efficiency (+28%) of the clap compared to rigid wings. Combined, our results suggest butterflies evolved a highly effective clap, which provides a mechanistic hypothesis for their unique wing morphology. Furthermore, our findings could aid the design of man-made flapping drones, boosting propulsive performance.
(Less)
- author
- Johansson, L. C. LU and Henningsson, P. LU
- organization
- publishing date
- 2021
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- aerodynamics, animal flight, butterflies, clap and fling, unsteady aerodynamics, wing morphology
- in
- Journal of the Royal Society, Interface
- volume
- 18
- issue
- 174
- article number
- 20200854
- publisher
- The Royal Society of Canada
- external identifiers
-
- pmid:33468023
- scopus:85100325655
- ISSN
- 1742-5662
- DOI
- 10.1098/rsif.2020.0854
- language
- English
- LU publication?
- yes
- id
- 39de965f-ff1e-48d2-9c95-a4478340a8d0
- date added to LUP
- 2021-02-12 11:30:23
- date last changed
- 2024-06-27 08:26:08
@article{39de965f-ff1e-48d2-9c95-a4478340a8d0,
abstract = {{<p>Butterflies look like no other flying animal, with unusually short, broad and large wings relative to their body size. Previous studies have suggested butterflies use several unsteady aerodynamic mechanisms to boost force production with upstroke wing clap being a prominent feature. When the wings clap together at the end of upstroke the air between the wings is pressed out, creating a jet, pushing the animal in the opposite direction. Although viewed, for the last 50 years, as a crucial mechanism in insect flight, quantitative aerodynamic measurements of the clap in freely flying animals are lacking. Using quantitative flow measurements behind freely flying butterflies during take-off and a mechanical clapper, we provide aerodynamic performance estimates for the wing clap. We show that flexible butterfly wings, forming a cupped shape during the upstroke and clap, thrust the butterfly forwards, while the downstroke is used for weight support. We further show that flexible wings dramatically increase the useful impulse (+22%) and efficiency (+28%) of the clap compared to rigid wings. Combined, our results suggest butterflies evolved a highly effective clap, which provides a mechanistic hypothesis for their unique wing morphology. Furthermore, our findings could aid the design of man-made flapping drones, boosting propulsive performance.</p>}},
author = {{Johansson, L. C. and Henningsson, P.}},
issn = {{1742-5662}},
keywords = {{aerodynamics; animal flight; butterflies; clap and fling; unsteady aerodynamics; wing morphology}},
language = {{eng}},
number = {{174}},
publisher = {{The Royal Society of Canada}},
series = {{Journal of the Royal Society, Interface}},
title = {{Butterflies fly using efficient propulsive clap mechanism owing to flexible wings}},
url = {{http://dx.doi.org/10.1098/rsif.2020.0854}},
doi = {{10.1098/rsif.2020.0854}},
volume = {{18}},
year = {{2021}},
}