The wings on the Air Force's latest experimental "X" plane can't stay on straight. And that's a good thing.
The X-53 -- formerly known as the "Active Aeroelastic Wing research vehicle," or AAW -- is pretty much your standard /A-18 fighter jet. Except its wings are flexible, twisting as the plane races through the air at transonic speeds -- and giving the plane better maneuverability, in the process.
Every plane's wings bend a little, when air pressure hits 'em. But that "aeroelastic effect" is usually a bad thing for the aircraft, dragging it down. So, "traditionally, air vehicles have been designed with stiff geometry in order to minimize aeroelastic instabilities," the Air Force notes.
The X-53, on the other hand, is built from the start to bend with the wind. Its flaps, ailerons, and actuators are repositioned, so that the air pressure bends the wing in a way that provides lift, instead of drag. A thinner skin allows the outer wing panels to twist up to 5 degrees.
The idea, a NASA fact sheet observes, dates back to the earliest days of flight.
When Orville Wright first took to the air on Dec. 17, 1903, he didn't have ailerons or flaps to control his airplane. Instead, the Wright brothers had chosen to twist or "warp" the wingtips of their craft in order to control its rolling or banking motion. Rather than using one of the craft's two control sticks to make the wingtips twist, they had devised a "saddle" in which the pilot lay. Cables connected the saddle to the tips of both wings. By moving his hips from side-to-side, the pilot warped the wingtips either up or down, providing the necessary control for the Wright Flyer to make turns.
The X-53 -- a cooperative effort between the Air Force Research Lab, NASA, and Boeing's Phantom Works, in the works since the beginning of the decade -- should give engineers "more freedom in designing more efficient, thinner, higher aspect-ratio wings for future high-performance aircraft while reducing the structural weight of the wings by 10 to 20 per cent," NASA says. "This will allow increased fuel efficiency or payload capability, along with potentially reduced radar signature. The technology also has application to a variety of other future aircraft, such as high-altitude, long-endurance unmanned aircraft, transports, and airliners."
(Big ups: AF Daily Report)
