We've already seen more than one micro air vehicle (MAV) that mimics the flapping-wing flight of bats. Scientists at the University of Southampton, however, recently announced something a little more subtle, but perhaps with wider applications. They've developed a bat-inspired membrane for use in MAV wings, that changes shape in order to improve its performance.

The membranous wing works like an artificial muscle, using electro-active polymers to stiffen and relax in response to an electrical current. That current is in turn automatically delivered in response to forces exerted upon the wing's flight surface, letting it instantaneously react accordingly.

As a result, the membranous wing offers better aerodynamics than a regular rigid wing, allowing for greater distances to be covered using the same amount of fuel. Also, unlike a flapping wing, it contains no moving parts that need to be maintained.

Already, the technology has been tested in a wind tunnel (pictured above), and on a miniature unmanned wing-in-ground vehicle flown over open water, both with promising results. The system may start showing up in commercial MAVs within five years.

"We've successfully demonstrated the fundamental feasibility of MAVs incorporating wings that respond to their environment, just like those of the bats that have fuelled our thinking," says project leader, Prof. Bharath Ganapathisubramani. "We've also shown in laboratory trials that active wings can dramatically alter the performance."

A rather grainy video of the test flights can be seen below.

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