X-56 Could Bring Breakthrough to Whole Industry
Thursday, 16 January 2014
By Dave Majumdar, posted at 5:25 p.m. EST
The Lockheed Martin X-56 multi-utility technology test-bed is expected to make its first flight with flexible wings early this year as the Air Force Research Laboratory-funded project works on demonstrating flutter suppression technology. “We hope to be flying here in the next couple of weeks,” said Peter Flick, the AFRL’s program manager for the X-56A demonstration effort, at AIAA’s SciTech 2014 conference.
Flutter causes an aircraft to flex rapidly as a result of multiple external physical forces – ultimately destroying the plane if the phenomenon lasts more than a short time.
Most aircraft have to be designed so that the flutter occurs outside of the plane’s normal flight envelope. But that results in weight and added drag, because aircraft features that increase speed and aerodynamic efficiency reduce airframe structural strength. The X-56 is designed to break those traditional design paradigms – for the entire aerospace industry.
Flick said that the X-56 is not a prototype, nor is the data generated proprietary – the idea is to advance the state of the art for the entire industry.
Suppressing flutter could lead to radically improved aircraft that would be lighter and faster as a result of X-56’s technology. This technology could be used on numerous aircraft types, for the military and for civilian transports. Indeed, the origins of the program are tied to the Air Force’s attempts to develop a high-altitude high-aspect ratio flying-wing reconnaissance aircraft.
The unmanned X-56 was built with a single center fuselage that can accept multiple different wings, said Jeff Beranek, Lockheed Martin Skunk Works chief engineer for the X-56 program. The test aircraft has to be unmanned because the testing is extremely hazardous. The program has taken steps to make sure that the plane can be recovered via a parachute, but the endeavor is far too dangerous for a human pilot.
Under the same program, Lockheed has built two center-bodies, which are powered by twin 85-pound-thrust JetCat P-400 micro jet engines. Those center-bodies can be fitted to a number of different wing sets designed for different test conditions. Lockheed has built one set of “stiff wings” and three sets of “flexible wings” for the aircraft, but thus far the plane has only flown with the stiff wings. The aircraft and wings are fitted with water tanks to simulate differing fuel weights and different center-of-gravity conditions.
Flick said that when the X-56 flies with its flexible wings, that’s when it will demonstrate it can sense flutter movements and then actively suppress those forces using its flight controls. The stiff wings are basically a control set for the overall experiment.
If the X-56 experiment proves successful, said Flick, the future program would be able to push the development of the technology for high-speed applications such as supersonic aircraft in the 2020s.