Bats actively modulate membrane compliance to control camber and reduce drag

Cheney, Jorn; Rehm, Jeremy; Swartz, Sharon; Breuer, Kenny

Abstract

Bat wing skin is exceptionally compliant and cambers significantly during flight. Plagiopatagiales proprii, arrays of small muscles embedded in the armwing membrane, are activated during flight and are hypothesized to modulate membrane tension. We examined the function of these muscles using Jamaican fruit bats, Artibeus jamaicensis. When these muscles were paralyzed using botulinum toxin, the bats preferred flight speed decreased and they were unable to fly at very low speeds. Paralysis of the plagiopatagiales also resulted in increased armwing camber consistent with a hypothesized role of modulating aeroelastic interactions. Other compensatory kinematics included increased downstroke angle and increased wingbeat amplitude. These results are consistent with the bats experiencing increased drag and flight power costs associated with the loss of wing-membrane control. Our results indicate that A. jamaicensis likely always employ their wing membrane muscles during sustained flight to control camber and to enhance flight efficiency over a wide flight envelope.

Citation

Cheney, J., Rehm, J., Swartz, S., & Breuer, K. (in press). Bats actively modulate membrane compliance to control camber and reduce drag. Journal of Experimental Biology, https://doi.org/10.1242/jeb.243974

• Journal Article Type: Article
• Acceptance Date: Jun 28, 2022
• Online Publication Date: Jul 14, 2022
• Deposit Date: Aug 11, 2021
• Publicly Available Date: Aug 9, 2022
• Print ISSN: 0022-0949
• Publisher: The Company of Biologists
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1242/jeb.243974
• Keywords: bats, wing membrane, animal flight, plagiopatagiales, membrane actuation, wing morphing, variable camber, wing membrane muscles
• Publisher URL: https://journals.biologists.com/jeb