Silent aircraft’s secrets
Aircrafts could be turned less noisy, if only designers make some changes in space shuttle rudders.
London: Aircrafts could be turned less noisy, if only designers make some changes in space shuttle rudders.
In a US patent filed last week, Airbus notes that the space shuttle`s rudder – the hinged steering surface on the rear of the tail fin – splits to present two large surfaces to the airstream, helping to brake the craft as it glides back to Earth.
Klaus Bender, of Airbus, said that the "spreading rudder" could slow airliners down too, reducing the need to deploy the noisy, flat air brakes on top of the wing.
By carving notches into the rudder``s trailing edge the noise-producing vortex can be broken and the loss of lift that occurs when ordinary air brakes are deployed, will be avoided.
With more lift from the wings, less engine power is needed as the aircraft approaches the runway, further reducing the noise.
"It seems plausible," New Scientist quoted Trevor Cox, an acoustics engineer at the University of Salford in the UK.
According to Cox, a serrated edge moving through a fluid produces eddy currents, which are more disorganised than those produced by a straight edge. That reduces the pressure difference and in turn creates less noise.
He added that the concept of serrated edges is also being studied for wind turbine blades, in the hope that they will produce less noise to annoy nearby residents.