Secrets of hovering kestrels could help city drones

Camera and motion capture technology enabled researchers to observe two Nankeen Kestrels, called Kevy and Jedda, as they hovered in a wind tunnel operated by RMIT.

Nankeen Kestrels are a small species of falcon native to Australia. Both birds came from a local hawk sanctuary and were used in falconry.

While being fed, the birds were fitted with little reflective stickers in much the same way human actors are when their movements are captured for visual effects in films, a process researchers say didn’t bother the kestrels.

Previous studies have examined birds flapping – less useful for gaining insights into how aircraft fly.

By contrast, it is thought lessons learned from studying kestrel’s wind-hovering flight could be particularly valuable for aviation engineers.

“Previous studies involved birds casually flying through turbulence and gusts within wind tunnels. In our study we tracked a unique wind hovering flight behaviour”, said RMIT lead researcher Dr Abdulghani Mohamed.

His team found the kestrels were excellent at keeping their heads still – moving less than 5mm – while hunting despite the buffeting air.

The key to a kestrel’s skill in staying still and coping with turbulence is their ability to change the shape of their wings, the researchers think.

At present, as anyone who has glanced out a jet window will know, aircraft with wings mostly use hinged control surfaces to control flight.

Now it’s thought the kestrels’ “wing-morphing” could inspire similar tech in planes and drones.

“It may be a more efficient way of achieving stable flight in fixed wing aircraft too,” said Dr Mohamed.

Strong wings and turbulence can limit the operation of drones. Those operating in windy environments, such as postal deliveries like those to Orkney, are limited by weather.