Have you ever watched dragonflies fly? During spring and summer, you can find them
zigging and zagging over ponds. Dragonflies eat a lot, and they constantly hunt for food.
What's more, they usually catch it--in mid-air. Zig! The dragonfly catches a gnat. Zag! It grabs a mosquito. Very few insects can out-fly the dragonfly. No matter how fast they go, no matter which way they turn, the dragonfly is usually able to follow. Two engineers at the University of Tennessee Space Institute have been studying the way that dragonflies fly. Dr. James Wu and Dr. Ahmad Vakili are studying ways to design a fighter plane that can change directions as quickly and easily as dragonflies can. Why is that important? "If you are in a fighter airplane, and another plane is after you, you want to be able to change direction quickly to outsmart the other plane," Dr. Vakili says.
A dragonfly's wings are the key to its flying ability, Dr. Wu and Dr. Vakili say. If you look closely, you will see that a dragonfly has two wings on each side of its body--a long front wing and a slightly shorter back wing. During flight, small but powerful "tornadoes" of air move along each of the dragonfly's front wings. These tiny tornadoes help the dragonfly maintain its lift, or ability to stay airborne. A dragonfly's back wings help keep the "tornadoes" from breaking up.
Dr. Wu and Dr. Vakili are studying ways to make fighter plane wings use air flow as efficiently as dragonfly wings. How do they do that? One way is to make large, three-dimensional models of dragonfly and other wings and test them in wind tunnels or water tunnels. Wind tunnels and water tunnels work in much the same way. Engineers place an object in the testing area, then direct a high speed stream of air or water toward it. They then measure the way the air or water flows around the object.
Does this mean that someday we'll have fighter planes that look like dragonflies? Dr. Wu and Dr. Vakili say no, because that would not be practical. They don't want wings that look like a dragonfly's. Rather, they want wings that work like a dragonfly's--designed to help fighter planes be able to change course quickly and out-fly their opponents.
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