Researchers Unlock Secret of How Bats Fly

RENEE MONTAGNE, Host:

We know a lot of things about the little mouse-like mammals called bats. We know they're nocturnal and that they listen to the echoes of their high-pitched sounds to locate prey and other objects.

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MONTAGNE: They've also inspired a well-known superhero.

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U: (Singing) Batman. Batman.

MONTAGNE: NPR's John Nielsen has more.

JOHN NIELSEN: In the movies, flying robots sometimes look like mutant helicopters or flying saucers. But Geoff Spedding, an aerospace engineer at the University of Southern California, says it might be time to start re-imagining these machines as smallish things that move around on artificial bat wings.

MONTAGNE: Maybe if they need to be highly maneuverable and readily controllable in confined spaces, maybe they should be wing flappers rather than propeller driven or helicopter-type things.

NIELSEN: Spedding says he came to that conclusion after he and some colleagues put a group of nectar eating bats into a high tech wind tunnel in the town of Lund in Sweden. The tunnel was filled with heavy fog and lit up by lasers, but the bats didn't seem to mind.

MONTAGNE: Bats learn to hang out in a nice calm dark section of the wind tunnel, and then they feed at the feeder, execute a very stereotypical u-turn and then go back to their perches, all day long.

NIELSEN: The fog lit by the lasers showed the scientists exactly how the bats kept themselves up in the air when they were hovering in front of the tiny food trays. What Spedding and his colleagues saw was that as a bat's wing flapped downwards, a small but potent vortex formed in the air above the leading edge of the wing.

MONTAGNE: I like to think of it as a tame tornado, if you like. And the high speeds associated with this swirling motion are responsible for generating suction on top of the wing. And that translates to lift.

NIELSEN: Coauthor Anders Hedenstrom of Lund University in Sweden says the secret is probably the incredible flexibility of a bat's wing, which is basically a super modified hand.

MONTAGNE: We think that they are actively controlling this vortex so it remains attached on top of the wing, because if it breaks away from the wing, it doesn't work in adding any lift any longer.

NIELSEN: John Nielsen, NPR News, Washington.

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MONTAGNE: It's NPR News. Transcript provided by NPR, Copyright NPR.