As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Saturday 24 November 2012

Owls' Ability to Fly in Acoustic Stealth Provides Clues to Mitigating Conventional Aircraft Noise


ScienceDaily (Nov. 19, 2012) — Owls have the uncanny ability to fly silently, relying on specialized plumage to reduce noise so they can hunt in acoustic stealth. Researchers from the University of Cambridge, England, are studying the owl's wing structure to better understand how it mitigates noise so they can apply that information to the design of conventional aircraft.

They present their findings at the American Physical Society's (APS) Division of Fluid Dynamics meeting, held Nov. 18 -- 20, in San Diego, Calif.

"Many owl species have developed specialized 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 with the department of applied mathematics and theoretical physics at 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. Conventional aircraft, which have hard trailing edges, are particularly noisy in this regard.


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