<
https://knowablemagazine.org/article/technology/2020/how-owls-fly-without-making-a-sound>
"Every owl fancier has a story of the first time they heard an owl — or,
rather, didn’t hear one. It’s unforgettable to see an enormous bird, whose
wingspan can reach more than six feet, slipping through the air without even a
whisper.
Justin Jaworski’s first close encounter came at a flying exhibition at the
Raptor Foundation near Cambridge, England. “They trained the owls to fly very
close to the audience,” he says. “My first experience was of ducking to avoid a
collision. I heard only a very slight swoosh after it passed.”
Laboratory measurements have shown that the slight swoosh made by a barn owl is
below the threshold of human hearing until the owl is about three feet away — a
feat of stealth that biologists and engineers are far from completely
understanding. But researchers from both disciplines are working to solve the
riddle of silent flight — some with the aim of designing quieter fans, turbine
blades and airplane wings.
Such owl-inspired innovations can reduce noise by as much as 10 decibels,
similar to the difference in noise between a passing truck and a passing car,
Jaworski and Nigel Peake write in an overview in the 2020
Annual Review of
Fluid Mechanics."
Via Esther Schindler.
Share and enjoy,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
