SSS 2009-04-10

（单词翻译）

This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

Thrill-seeking stunt¹ pilots spend years learning to perform maneuvers² that birds and bees know how to do from birth. Now a new study in the journal Science shows that, although birds and bugs³ don’t go to flight school, it’s like they’re reading from the same manual when it comes to making turns.

If you’ve ever watched a hummingbird⁴ or seen a bat chase after a moth⁵, you know that critters that flap their wings to fly are amazing aerial acrobats⁶, capable of hovering⁷ near a flower or turning on a dime⁸. But how do they do it? And does the tiniest fruit fly use the same tricks as a hummingbird or a bat?

The scientists studied videos of seven different kinds of winged beasts, from bluebottle flies to a cockatoo. And they found that they all used a technique called flapping counter-torque to recover from a turn. So, when a bird banks right, its left wing moves faster on the downstroke while the right is faster on the upstroke, which slows the animal’s rotation⁹. And no matter what their size, critters with a similar wingspan to body length ratio, like a fruitfly and a hummingbird, need the same number of flaps to finish a turn. And you thought such aeronautical¹⁰ insights would remain hidden until pigs fly.

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin