MICHAEL PHELAN / LONDON
Designer says wingtip-mounted device can perform far better than winglets
A French invention designed to eliminate wingtip vortices could enable future aircraft designs to benefit from significantly lower lift-induced drag. French aeronautical teacher Christian Hugues claims his Minix device - a hollow cylindrical tube attached to an aircraft's wingtip - could reduce induced drag by 8%, while increasing lift by 5.4%.
The tube, made of Kevlar and carbon composite, has spiral slits cut into its length. It works on the principle that the vortices generated at the wingtip will hit the wing at the same distance inboard of the tip as the wing's thickness. As the pressure exerted by the vortex on the wing surface increases, flow escapes through the slits and is dissipated into a linear flow through the open rear of the tube.
Hugues obtained a French patent for his device in May following eight years of work, and says the design performs far better than conventional winglets. "While winglets can reduce vortex pressure around the wingtip, Minix can eliminate the vortex completely," he says.
Hugues has tested his invention in a windtunnel and predicts an 8% induced drag reduction for a wing with an aspect ratio of eight at a Reynolds number of 7.5 x 106. He says the application is adaptable to all aerofoil shapes and sizes, including propeller and helicopter blades. More testing is needed to tailor the design to larger wings and for higher Reynolds number conditions, however.
Hugues says that French aircraft racer Xavier Beck plans to use the Minix wingtip devices when he competes in the Reno, Nevada, air races next year, and he hopes to equip an 8m (26ft)-span model of the Airbus A380 that is due to fly in September. He says that French and US manufacturers have also expressed interest in using the device.
Source: Flight International