Robot Bat Wing Reveals How Mammals Took Flight and Beat Birds at Their Own Game

From ExtremeTech:

Bats are flying mammals. Think about that. Many millions of years after birds hollowed out their very bones in pursuit of flight, some gliding, insectivorous squirrel-thing was born with a slight deformity. Perhaps it was as simple as a double-joint that let the animal raise and lower its arm while gliding, and perhaps that freak could slightly increase its range as a result. The remarkable path taken by bat physiology since that day has produced a model for flight that might well be more efficient than a bird's. That's right: Mammals win again.

For some time, engineers have puzzled over how bats could generate so much lift and so little drag, and how they could seem to do it while using less energy than even more specialized flyers like moths or birds. Wind tunnel experiments offered insight, implicating the leathery skin that stretches between the wing's four primary fingers. The soft wing material allows the bat to fold the wing and spill air even more effectively than a bird, on a given upstroke. This means that the lift generated in the downstroke, itself augmented by using the fingers to cup the air, won't be cancelled out when the wing comes back up.

This week, a team of researchers decided to ditch the unreliable little creatures in favor of an automated solution - like so many Americans, these test bats have seen their industry mechanized. Brown University scientists built a mechanical wing to precisely mimic the structure and range of motion of the real thing, and to measure the effects of tiny changes in those motions. "We can't ask a bat to flap at a frequency of eight hertz then raise it to nine hertz so we can see what difference that makes," Bahlman said. "They don't really cooperate that way."

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