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Barn Owl Reveals How Birds Fly in High Winds

Barn Owl Reveals How Birds Fly in High Winds

Friday, 23 October, 2020 - 05:45
Lily the barn owl demonstrates wing-morphing to cope with gusts in flight.

Scientists from the University of Bristol and the Royal Veterinary College have discovered how birds are able to fly in gusty conditions in a study involving the barn owl bird.

Birds routinely fly in high winds as fast as their flight speed. So the ability to cope with strong and sudden changes in wind is essential for their survival. The researchers tried to uncover the mechanism behind this flying, which could help inform the development of bio-inspired small-scale aircraft in the future.

In the study published in the journal Proceedings of the Royal Society, the team conducted an experiment at the Structure and Motion Laboratory at the Royal Veterinary College, during which they exposed a barn owl to a range of fan-generated vertical gusts, the strongest of which was as fast as her flight speed.

The experiment began with very gentle gusts in case the owl had any difficulties, but soon the researchers found that even at the highest gust speeds, it was unperturbed; she flew straight through to get the food reward.

"The bird flew through the bumpy gusts and consistently kept her head and torso amazingly stable over the trajectory, as if she was flying with a suspension system. When we analyzed it, we found that it achieves this stability from the mass in her wings. For reference, each of our upper limbs is about 5% of our body weight; for a bird it's about double, and they use that mass to effectively absorb the gust," explained Dr. Jorn Cheney from the Royal Veterinary College in a report published by the Bristol University.

"Perhaps most exciting is the discovery that the very fastest part of the suspension effect is built into the mechanics of the wings, so birds don't actively need to do anything for it to work. Like when a baseball or tennis player chooses the sweetspot of a bat or racquet, his hand is not jarred because the force there cancels out. This markedly reduces the disturbance to the body. The bird does the same thing and automatically chooses the sweetspot in its wing," he added.

According to Dr. Shane Windsor from the Department of Aerospace Engineering at the University of Bristol, the next step for the research, which was funded by the European Research Council (ERC) and the Air Force Office of Scientific Research, is to develop bio-inspired suspension systems for small-scale aircraft.

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