Read through the King Air Wikipedia page and you’ll quickly discover one of the main focuses of Beechcraft’s development over the decades: an unending mission to quiet and reduce the noise their aircraft produces. A team at the University of Cambridge might have came up with the next big innovation to propel the quest for quiet forward; found by studying the wings of large owls, master of the silent swoop. They discovered the birds’ flight feathers, (utilized to create lift), have a downy covering consisting of a flexible comb of bristles along the leading edge, with a porous fringe on the trailing edge.
“No other bird has this sort of intricate wing structure,” said Professor Nigel Peake of Cambridge’s Department of Applied Mathematics and Theoretical Physics. “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.”
According to Professor Peake, noise caused by a wing – whether bird, plane or fan – begins at the trailing edge where turbulent air passes over the wing surface. The team reasoned that the tiny hairs covering the oil feathers could be reducing the trailing-edge noise.
With this thought in mind, the Cambridge team, working with Virginia Tech, Lehigh and Florida Atlantic Universities, created a prototype material of 3D-printed plastic that mimicked the owls’ natural ability. The material contains set ribs, or “finlets” that sits in front of the blade’s trailing edge. They fitted the material onto full-sized wind turbine blades and tested it in a wind tunnel. The end result was a 10 decibel noise generation reduction (a notable amount since noise is measured logarithmically), that did not significantly affect aerodynamics.
The researchers plan to continue to optimize the coating with the first real world scenario being the application to a functioning wind turbine. The process of incorporating it onto an aeroplane will be more complicated. This has a high likelihood of being pursued since successful implementation would be highly beneficial to authorities, plane makers and airports looking to minimize noise.