UAVs seeking to ride thermal air currents to increase their air time while using less fuel would do well to listen to the lessons taught by peregrine falcons.

Zsuzsa Ákos at Eötvös University in Hungary and a few pals suggest another approach inspired by videos and GPS tracking of peregrine falcons in flight. It turns out that these masters of thermal soaring employ a counter-intuitive strategy: instead of spiralling in one direction to stay with a single thermal, they constantly change the direction of their spirals.

At first glance, that seems odd. Change the direction of your spiral and you immediately fly out of a thermal. But Ákos and co have simulated this strategy and say there is a method in this madness.

The key is to recognise that the atmosphere is filled with thermals that are distributed in 3D space in complex ways. According to their simulation, the reason why the direction change works so well is that it allows the flier to sample the volume of the atmosphere more effectively, making it more likely that it will find a better thermal. Crucially, this works particularly well when turbulence is present.

The new strategy is computationally simple and so requires little power to implement. So the thinking is that UAVs could fly for longer, using less power, if they copied the falcon’s flying behaviour.

By Gary Mortimer

Founder and Editor of sUAS News | Gary Mortimer has been a commercial balloon pilot for 25 years and also flies full-size helicopters. Prior to that, he made tea and coffee in air traffic control towers across the UK as a member of the Royal Air Force.