Natures wonders: Owl flight silent (Introduction)

by David Turell , Monday, June 22, 2015, 14:36 (3440 days ago) @ David Turell

Owls fly to hunt prey and that flight is relatively noiseless:-http://phys.org/news/2015-06-silent-flights-owls-turbines-planes.html-"'Many owls - primarily large owls like barn owls or great grey owls - can hunt by stealth, swooping down and capturing their prey undetected," said Professor Nigel Peake of Cambridge's Department of Applied Mathematics and Theoretical Physics, who led the research. "While we've known this for centuries, what hasn't been known is how or why owls are able to fly in silence."-"Peake and his collaborators at Virginia Tech, Lehigh and Florida Atlantic Universities used high resolution microscopy to examine owl feathers in fine detail. They observed that the flight feathers on an owl's wing have a downy covering, which resembles a forest canopy when viewed from above. In addition to this fluffy canopy, owl wings also have a flexible comb of evenly-spaced bristles along their leading edge, and a porous and elastic fringe on the trailing edge.-"'No other bird has this sort of intricate wing structure," said Peake. "Much of the noise caused by a wing - whether it's attached to a bird, a plane or a fan - originates at the trailing edge where the air passing over the wing surface is turbulent. The structure of an owl's wing serves to reduce noise by smoothing the passage of air as it passes over the wing - scattering the sound so their prey can't hear them coming.'"