Cossack the eagle reveals his turbulence secrets

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Media captionWatch the eagle above the Brecon Beacons

An eagle called Cossack has been fitted with a "black box" to reveal his secret weapon against turbulence.

The steppe eagle flew 45 times over the Brecon Beacons wearing a miniature rucksack packed with scientific instruments.

The experiment showed that by collapsing his wings in heavy wind, Cossack can fly in conditions that would have grounded an aircraft.

Scientists say birds such as vultures and kites may use the same technique.

Image copyright Graham Taylor
Image caption The black box recorded acceleration, rotation and airspeed

During each "wing tuck" Cossack's wings are, for a split-second, folded beneath his body so that he is effectively falling. This occurs up to three times a minute in some conditions.

Study leader Professor Graham Taylor, from Oxford University's Department of Zoology, said: "Soaring flight may appear effortless but it isn't a free also puts an enormous strain on its flight muscles."

He compared the technique to suspension on a car stopping a disturbing ride.

The 75g (3 oz) "black box", which did not interfere with flying, tracked his position and recorded acceleration, rotation rate and airspeed.

Prof Taylor believes the lessons learned from Cossack could be useful to human aviation.

"This kind of technique could potentially be used to keep micro air vehicles aloft even in very windy conditions," he said.

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