Bats use weighty wings to land upside down

 November 16, 2015

Compared to birds and insects, bats have heavy wings for their body size. Those comparatively cumbersome flappers might seem a detriment to maneuverability, but new research shows that bats' extra wing mass makes possible a quintessential bit of aerobatics: the ability to land upside down.

"Bats land in a unique way," said Sharon Swartz, a biologist at Brown University who was a senior author of the new research along with Kenny Breuer from Brown's School of Engineering. "They have to go from flying with their heads forward to executing an acrobatic maneuver that puts them head down and feet up. No other flying animal lands the same way as bats do."

But exactly how they are able to generate the forces necessary to perform those maneuvers hadn't been clear.

"When they come in to land they're not moving very fast, which makes it hard to generate the aerodynamic forces needed to reorient themselves," Breuer said. "So the question is, how do bats get themselves in position to land?"

Using a special flight enclosure, high-speed cameras and some sophisticated computer modeling, the researchers showed that it has a lot to do with wing mass and inertia.

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