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It's easier for birds to turn than for a person to swivel in a chair, researcher Tyson L. Hedrick says. ((Donald Metzner, Courtesy Cornell Lab of Ornithology/AP))

Three U.S. scientists have figured out how flying animals make a turn, and then continue straight on a new course.

It's remarkably easy, said lead researcher Tyson L. Hedrick of the biology department of the University of North Carolina. It's even easier than a person swivelling in a desk chair, he said.

That manoeuvre takes three steps: Push off with one foot, roll through the turn, then stop with the other foot.

But for a bat, bird or bee, turning is easier. Start the turn, and then flap normally to continue on the new course.

"We didn't expect things to fall out this neatly," he said.

Researchers found the process is the same for all flying animals from fruit flies to large birds.

Hedrick and two colleagues showed that flapping fliers have a passive mechanism called flapping counter-torque (FCT) which dampens the effects of the turn.

Their FCT model "also shows how animals may simultaneously specialize in both manoeuvrability and stability [at the cost of efficiency]," and links the animal's structure, wing kinematics, manoeuvrability, and flight dynamics, the abstract of their article said. It was published in the journal Science on Friday.

The research could aid the study of robotic flying machines, said Bret W. Tobalske of the University of Montana.

But there are still some major barriers.

Turning is one of the three motions in flying. It's called yaw in aviation, but there are still the up-and-down — pitch — and the roll, the tilt to left or right.

"We picked basically the simplest turn you can imagine to make comparison," Hedrick said.  

Hedrick worked with Bo Cheng and  Xinyan Deng, both with the mechanical engineering department of the University of Delaware.

With files from the Associated Press