Wings that waggle cut drag
Wings that redirect air to waggle sideways could cut airline emissions (and fuel bills) by 20 per cent according to research by a group of British universities.
The new approach, which promises to dramatically reduce mid-flight drag, uses tiny air-powered jets that redirect the air, making it flow sideways back and forth over the wing.
The jets work by the Helmholtz resonance principle – when air is forced into a cavity the pressure increases, which forces air out and sucks it back in again, causing an oscillation – the same phenomenon that happens when blowing over a bottle.
Dr Duncan Lockerby, from the University of Warwick, who is leading the project, said: "This has come as a bit of a surprise to all of us in the aerodynamics community. It was discovered, essentially, by waggling a piece of wing from side to side in a wind tunnel."
Engineers have known for some time that tiny ridges known as ‘riblets’ can reduce skin-friction drag by around 5 per cent, but it appears that the new micro-jet system being developed by Dr Lockerby and his colleagues could achieve reductions of up to 40 per cent.
"The truth is, we’re not exactly sure why this technology reduces drag," said Lockerby, "but with the pressure of climate change we can’t afford to wait around to find out. So we are pushing ahead with prototypes and have a separate three-year project to look more carefully at the physics behind it."
The research is funded by the Engineering and Physical Sciences Research Council (EPSRC) and Airbus, with an additional contribution from EADS Innovation Works. It is being carried out with scientists at Cardiff, Imperial, Sheffield, and Queen's University Belfast.
Simon Crook, EPSRC aerospace manager, said: "This could help drastically reduce the environmental cost of flying. Research like this highlights the way UK scientists and engineers continue to make significant contributions to our lives."
The work is still at concept stage, but it is hoped the new wings could be ready for trials as early as 2012.
If successful this technology could also have a major impact on the aerodynamic design and fuel consumptions of cars, boats and trains.