Flying drone copies bat flapping

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MADRID, May 30 (UPI) -- A drone that mimics the way a bat changes its wing shape in flight could make small unmanned vehicles more agile in flight, U.S. and Spanish researchers say.

"Bat wings are highly articulated, with wing skeletons very similar to those of human arms and hands," said Julian Colorado of the Polytechnic University of Madrid. "The way bats change the shape of their wings has great potential for improving the maneuverability of micro air vehicles."

Colorado and colleagues in Madrid and from Brown University in Rhode Island have built a drone with an 18-inch wingspan inspired by a type of bat called the gray-headed flying fox, capable of changing the profile of its wing between the downstroke and upstroke, NewScientist.com reported Wednesday.

On the downstroke a large wing surface area is required to generate lift and propulsion, but on the upstroke a large area creates drag, so a bat folds the wing inwards on the upstroke.

In the "Batbot," the extension and contraction of the wing is controlled by shape-memory alloy wires that switch between two shapes when different currents are applied, pulling in to slim the wing profile on the upstroke.