Bird-inspired airplane wings could boost flight performance
Rows of featherlike flaps improve their lift and reduce drag
The overlapping rows of covert feathers on this brown pelican’s wings can be distinguished by their light gray color. Wing flaps that mimic these tufts could improve the flight performance of airplanes.
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Airplane plumage might be the next big thing in aviation.
Bird wings are shaped in part by overlapping rows of feathery tufts. These spread out from near the flyers’ shoulders. Known as “covert feathers,” they help birds maneuver through the air. And now, research shows that putting similar features on airplane wings may boost their performance.
Aircraft wings lined with rows of lightweight flaps that mimic covert feathers could get better lift. That’s the upward force that keeps birds and planes in the air. More birdlike plane wings could also cut through the sky with less air resistance, or drag. And they might even prevent stall — a sudden loss of lift that can happen when a wing meets oncoming air at a high angle.
Researchers shared these findings October 28. The results appeared in Proceedings of the National Academy of Sciences.
It’s a bird. It’s a plane. It’s a plane … with feathers?
The wings of many planes already have flaps and spoilers. Those components are generally controlled by pilots to adjust two aerodynamic forces: lift and drag. Bird-inspired flaps, in contrast, would fan out automatically when a plane’s wings meet oncoming air at a high angle. This type of scenario is known as a high “angle of attack.”
“They’re not controlled by some motor,” says Aimy Wissa. She’s an engineer at Princeton University in New Jersey. What’s more, these flaps would be “all over the wings, not just in the back or front.”
Wissa was part of a team that ran experiments in a wind tunnel with model plane wings. This allowed them to see how multiple rows of flaps affected the flow of air around airfoils (curved structures that generate lift as air flows around them).
The flaps turned out to affect flow in two ways. Flaps near the front of an airfoil helped keep the air flowing around it closer to the wing. That improved the wing’s lift and reduced its drag. Adding more rows of flaps enhanced the effect.
Installing a single row of flaps near the rear of an airfoil brought a different benefit. It blocked high-pressure air near the trailing edge of the wing from creeping toward the wing front. That’s key, because low pressure is needed in the front to produce lift, Wissa explains. Adding five rows of flaps to airfoils improved lift by up to 45 percent. At the same time, it reduced drag by 31 percent.
Further tests with remote-controlled aircraft showed that the bird-inspired flaps reduced stall and improved flight stability. That might be especially helpful while flying through heavy gusts, or during landings on very short runways. Without the flaps, you might not be able to safely complete such maneuvers, Wissa says. “But now, you can.”
