SUPER-NATURE: The owl is an engineering ‘spirit animal’
If birds could be ninjas, owls would make the best ones. Silent and agile, their stealth ability has inspired scientists to create quieter movement for airfoil designs across everyday technologies.
MANASEE WAGH: Since the earliest days of human flight, inventors have been inspired by birds. The Wright brothers, for instance, recognized that birds’ wing shapes were crucial in getting off the ground, so they copied those properties in their mechanical airplane design. Yet scientists are still befuddled when faced with the noisy problem of trailing-edge dissonance, a phenomenon in which air moves noisily over the back edge of an airfoil; it’s the last bit of an airplane wing the air touches as it whooshes over it from front to back…
If birds could be ninjas, owls would make the best ones. Silent and agile, the winged creatures leave their prey with no time to escape as they swoop in for the kill. This stealth ability has inspired scientists to create quieter movement for airfoil designs across everyday technologies, including aircraft, vehicles, drones, and wind turbines…
“I would say that the owl has been a long-standing spirit animal, if you will, for the air acoustics community,” Justin Jaworski, a mechanical engineer at Lehigh University in Bethlehem, Pennsylvania, tells Popular Mechanics. “[W]hen you’ve exhausted a lot of innovative ideas, you look for other means of inspiration. And the owl has been a source of inspiration for at least 80 years”…
Owls are quiet so that their prey, which have very sensitive hearing, don’t notice them coming. When owls fly past a very sensitive array of microphones to gauge their sound levels, researchers have found that they are virtually silent, at least to human ears. To find out why, scientists have converted owl-inspired airfoil designs into theoretical models. “Being able to develop those simple computational models and get insights from them is helpful in terms of making much more sophisticated models that can incorporate more realistic features of the owl wing,” Jaworski says.
David Lentink of Stanford University, for example, studies bird flight and translates it into engineering design. Lentink investigated the wings of a swift, which stays airborne for a year, non-stop, after leaving the nest. It eats flying insects, scoops water onto its wings, and even mates in the air. Lentink’s team of undergraduate students then developed a drone whose design is based on the swift’s flying behavior…
Like other birds of prey, owls’ wings have various structural parts and arrangements, and lots of different shapes and sizes of feathers. Trying to model these complex biological parts, whose specific functions aren’t even fully understood yet, is challenging, says Jaworski. “Is it one part of the wing that makes them so quiet? Or is it the combination of several parts of the wing? And how are they using it? That’s what makes it difficult. There’s just an infinite number of designs for edge geometries you could look at. You know, it’s still an idealization. We’re looking for some insight that maybe will guide the next research program”. SOURCE…
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