Owls have the uncanny ability to fly silently, relying on specialised plumage to reduce noise so they can hunt in acoustic stealth. Researchers from the University of Cambridge, are studying the owl’s wing structure to better understand how it mitigates noise so they can apply that data to the design of conventional aircraft.
“Many owl species have developed specialised plumage to effectively eliminate the aerodynamic noise from their wings, which allows them to hunt and capture their prey using their ears alone,” said Justin Jaworski from the University of Cambridge. “No one knows exactly how owls achieve this acoustic stealth, and the reasons for this feat are largely speculative based on comparisons of owl feathers and physiology to other not-so-quiet birds such as pigeons.”
All wings, either natural or engineered, create turbulent eddies as they cut through the air. When these eddies hit the trailing edge of the wing, they are amplified and scattered as sound. Aircraft, which have hard trailing edges, are particularly noisy in this regard.
The researchers attempted to unravel the owl mystery by developing a theoretical basis for the owl’s ability to mitigate sound from the trailing edge of its wing. Earlier owl noise experiments suggest that their wing noise is much less dependent on air speed and that there is a large reduction of high frequency noise across a range where human ears are most sensitive. Using math models, the researchers demonstrated that elastic and porous properties of a trailing edge could be tuned so that aerodynamic noise would depend on the flight speed as if there were no edge at all.
“Many owl species have developed specialised plumage to effectively eliminate the aerodynamic noise from their wings, which allows them to hunt and capture their prey using their ears alone,” said Justin Jaworski from the University of Cambridge. “No one knows exactly how owls achieve this acoustic stealth, and the reasons for this feat are largely speculative based on comparisons of owl feathers and physiology to other not-so-quiet birds such as pigeons.”
All wings, either natural or engineered, create turbulent eddies as they cut through the air. When these eddies hit the trailing edge of the wing, they are amplified and scattered as sound. Aircraft, which have hard trailing edges, are particularly noisy in this regard.
The researchers attempted to unravel the owl mystery by developing a theoretical basis for the owl’s ability to mitigate sound from the trailing edge of its wing. Earlier owl noise experiments suggest that their wing noise is much less dependent on air speed and that there is a large reduction of high frequency noise across a range where human ears are most sensitive. Using math models, the researchers demonstrated that elastic and porous properties of a trailing edge could be tuned so that aerodynamic noise would depend on the flight speed as if there were no edge at all.
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