Scientists start to unlock secrets of bird flight

April 9, 2009 By RANDOLPH E. SCHMID , AP Science Writer
In this photograph provided by the Journal of Science, a female hummingbird is seen in flight. Researchers have determined that when birds, bats or bugs make a turn, all they have to do is start flapping their wings normally again and they straighten right out, an easier process than expected. (AP Photo/Journal of Science, Edwin Yoo)

(AP) -- For millennia, people have watched the birds and bees and wondered: "How do they do that?" Thanks to high-speed film and some persistent scientists, at least one of the secrets of flight is now revealed. When birds, bats or bugs make a turn, all they have to do is start flapping their wings normally again and they straighten right out.

That came as a surprise to researchers who thought turning and stopping took more steps.

Lead researcher Tyson L. Hedrick of the University of North Carolina compared it to sitting at a desk chair and turning left. It's a three-step process, launch the turn by pushing with one foot, turn, then stop by pushing with the other.

It's a simpler, one-step process for flying animals, he explained in a telephone interview, launch a turn and then simply flap normally to end it and fly away.

The findings are reported in Friday's edition of the journal Science.

"We didn't expect things to fall out this neatly," he said, particularly since the process is the same for animals of all sizes from the fruit fly to the bat to the cockatoo.

"It's sort of unusual" to find a general rule to cover six orders of magnitude in size, he said.

The findings should help in the development of robotic flying machines, he said.

But, of course, this study focuses only on one type of maneuver, turning left or right, which is known as yaw in aviation.

There's still pitch - nose up or nose down - and roll, which is tilting left or right, to be dealt with.

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

The situation does become more complicated with more complex maneuvers, "and that is clearly the next step," he said.

The report was welcomed by Bret W. Tobalske of the University of Montana, who said "the results will inform all future research into maneuvering flight in animals and biomimetic flying robots."

"Now that technology has developed to the point where detailed measurements of flapping maneuvers have become feasible, a world of comparative research is opening," Tobalske, who was not part of the research team, said in a commentary on the paper.

The research was funded by the National Science Foundation.

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On the Net:

Science: http://www.sciencemag.org

©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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6 comments

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Ashy
1 / 5 (1) Apr 10, 2009
I wonder why some birds can stay at one place when flying and other birds can't. Maybe it depends on plumage flexibility...
moj85
1 / 5 (1) Apr 10, 2009
It takes an immense amount of energy to 'hover'. It's probable that only some birds (the ones that need to eat from flowers with difficult-to-find nectar) evolved the need to expend the energy to hover, while most other birds do not require that amount of control to catch their prey.
Ashy
1 / 5 (1) Apr 11, 2009
I asking about physical model, not about biological reasons.
siira
not rated yet Apr 13, 2009
ever noticed a bird in a dive? they pull up the tail rather than down. that should pitch up the body!
Ashy
1 / 5 (1) Apr 13, 2009
Tail is stabilizer, it allows control horizontal and vertical components of motion. But at the point of aerodynamics this process occurs only at motion, not in stay position.
siira
not rated yet Apr 15, 2009
But a bird in a dive is in motion!
i have seen most of the birds 'hover' even though it may be for a splits of a second. i think most of them do not feel the need to hover.

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