Owls are nearly noiseless hunters, swooping down on prey without any warning whoosh. How do they do it?
We’ve known that the leading edge of an owl's wing has a comb of stiff feathers. And the trailing edge has a flexible fringe, unlike the rigid trailing edge of a conventional bird wing. These two features contribute to a structure that produces almost no noise as it rushes through the air.
Now it appears that these predators have a third trick up their sleeves—or rather, wings—that allow them to be so silent but deadly.
Researchers modeled the effect of the layer of down on the wing’s top surface. And it looks like that fluffy stuff absorbs sound too. The work was presented at a meeting of the American Physical Society's Division of Fluid Dynamics. [Justin Jaworski and Nigel Peake, Vortex Noise Reductions from a Flexible Model of Owl Down]
Mimicking owl wing down may lead to new sound-proofing materials. Down and the other silencing features could inspire wind turbines and plane engines that produce less noise and fewer vibrations. So that all we hear is [silence].
—Sophie Bushwick