Owls hold secret to silent planes
Soon, a legacy greater than Hedwig
Quieter planes, PCs and more efficient wind farms are among the unusual anticipated improvements to follow a study of the owl’s hunting techniques. The study is a collaboration between the UK’s Cambridge University and US Virginia Tech, Lehigh and Florida Atlantic Universities.
Initial tests to coat wind turbines with a prototype coating to mimic owl wings will be presented to the American Institute of Aeronautics and Astronautics Aeroacoustics Conferences on 22 June.
Professor Nigel Peake, Cambridge Department of Applied Mathematics and Theoretical Physics, commented, ‘Many owls – primarily large owls like barn owls and great grey owls – can hunt by stealth, swooping down and capturing their prey unnoticed. While we’ve known this for centuries, what hasn’t been known is how or why owls are able to fly in silence.’
High-resolution microscopy was employed to examine owl feathers in detail, noting that owl wings have a downy covering, a flexible comb of bristles among their leading edge and a porous, elastic fringe on the trailing edge.
Peake continued, ‘Much of the noise caused by a wing – whether it’s attached to a bird or a plane or a fan – originates at the trailing edge where the air passing over the wing’s surface is turbulent. The structure of an owl’s wing serves to reduce noise by smoothing the passage of air as it passes over – scattering the sound so their prey can’t hear them coming. No other bird has this sort of intricate wing structure.’
Image credited to the Windsor Star
As turbines are braked to reduce noise, fans adopting the owl structure will be able to run at a higher speed without increasing the noise produced. This discovery could lead to quieter planes, PC cooling systems and even more efficient wind farms. A test coating modelled on a wedding veil has proven successful, although is yet to be optimised and is unsuitable for use with turbines or planes.
Materials scientists have long been inspired by the natural world, including research into the strongest material known to man, limpet ‘teeth’, the lotus leaf’s self-cleaning capabilities and coating vaccines in MOFs as inspired by seashells.
By Khai Trung Le
