How big-eared bats could help drone design

A bat flies through smoke toward food attached to a stick, so the air patterns it creates can be tracked(Credit: Anders Hedenström)

When it comes to inventions inspired by animals, it seems like geckos get all the attention from scientists and engineers these days. But researchers at Sweden's Lund University have turned their observations to the long-eared brown bat and what they've discovered just might help improve drone design.

To carry out the work, a team of researchers led by Lund department of biology senior lecturer Christoffer Johansson placed bats inside a wind tunnel – those bats were trained to fly toward a stick containing food. The wind tunnel was filled with thin smoke and a laser was aimed through the smoke just behind the bats, to see how the air was affected by their flight. The bats flew at a speed of between one and five meters per second (about three to 16 feet per second).

What they found was that the large ears on the brown long-eared bats (Plecotus auritus) work much in the same way airplane wings do – they create lift. This was contrary to previously-held beliefs that while they could assist with echolocation, the sizable appendages were more of a hinderance than a help in terms of flight.

Additionally, Johansson and his team found that the bats were able to efficiently create thrust while flying slowly by holding their wings high and away from their body at the end of each beat. This allowed them to create upstroke air wakes that were formed inside the wake of the downstrokes.

"This specific way of generating power could lead to new aerodynamic control mechanisms for drones in the future, inspired by flying animals," says Johansson.

The work of the researchers was published last week online in the journal Scientific Reports.

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