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Technology : Wings make flying less of a drag

发布时间:2019-02-27 05:17:01来源:未知点击:

By Kurt Kleiner A WING design that reduces drag at supersonic speeds could make it easier to operate affordable supersonic passenger jets. NASA recently finished testing the new design at its Dryden Flight Research Center in Edwards, California. Friction across the skin of an aircraft accounts for around half the total drag on a supersonic plane. Increased drag means planes must carry more fuel in bigger tanks, so it has a major impact on the weight of aircraft and the economics of supersonic flight. “With an 8 per cent reduction in skin friction drag, you can expect to save 50 000 pounds off the weight of the [700 000 pound] airplane,” says Jeff Lavell, project manager for the new design, which was developed at NASA’s Langley Research Center in Hampton, Virginia. During subsonic flight, air passes over most of the wing area in a smooth, laminar stream that hugs the surface. But at supersonic speeds, the air becomes turbulent just a few centimetres behind the wing’s leading edge, resulting in a massive increase in drag. The idea is to attach a perforated titanium panel to the top surface of the wing. Using a fan, the designers suck some of the air passing over the plate through 10 million tiny holes which keep the air flow laminar over most of the wing. In test flights, the second skin increased the lift-to-drag ratio of the wing by 10 per cent. The new wing was designed by an aerospace consortium composed of Boeing, Rockwell and McDonnell Douglas. The NASA experiments used an F-16XL, which has a large delta wing. The aerodynamic sleeve was fitted over the wing on the left side. The aircraft flies at Mach 2—twice the speed of sound. This is roughly the speed envisaged for the High-Speed Civil Transport,