Three key findings emerged from the data. They all point to the plagiopatagiales modulating skin stiffness.
One result was that the muscle activation and relaxation follows a distinct pattern during flight: They tense on the downstroke and relax on the upstroke.
"This is the first study showing that bats turn these muscles on and off during a typical wingbeat cycle," said co-author Sharon Swartz, professor of biology at Brown.
Another finding was that the muscles don't act individually. Instead they exert their force in synchrony, providing enough collective strength to stiffen the wing.
Finally, Cheney found, the muscles appeared to activate with different timing at different flight speeds. As the bats flew faster, they tensed the muscles sooner in the upstroke-downstroke cycle.
In other words, the data suggested that the muscles do not behave passively but actively and collectively in keeping with conditions of flight.
None of the data, however, preclude the muscles from serving a sensory function as well.
Technological insight, too
Cheney's findings fit into a larger program of research at Brown between the labs of biologist Swartz and co-author Kenneth Breuer, professor of engineering, in which, as Breuer puts it, they are "using biology to inspire engineering and using engineering to inspire biology."
In parallel with studies of real bats, the team has also built a robotic bat wing that incorporates their biological observations. Then they use the wing to generate data from experiments that they could never do with living creatures, such as precisely varying kinematic parameters like wingbeat frequency and amplitude, or the degree of wing folding during flapping.
In a separate paper in the same edition of Bioinspiration and Biomimetics, Swartz, Breuer, and former student Joe Bahlman report on how energy costs and aerodynam
|Contact: David Orenstein|