The Lockheed Martin X-56A is a modular unmanned aerial vehicle designed to explore high altitude, long endurance (HALE) flight technologies for use in future military unmanned reconnaissance aircraft, as well as contributing knowledge to the future X-54 low-boom supersonic research programme, and future low emissions transport aircraft. “MUTT” stands for Multi-Use Technology Testbed.
MUTT is one of the Air Force’s newest X-planes, designated X-56A. The 7.5-foot-long aircraft has a 28-foot wingspan and will be powered by two 52-pound thrust JetCat P200-SX turbine engines. It is being built in California under contract to Lockheed Martin Corp., which will conduct the flight experiments for the Air Force Research Laboratory (AFRL).
“Flexible wings and fuselages can result in significant reductions in the structural weight of aircraft,” says Gary Martin, deputy project manager for NASA’s Subsonic Fixed Wing Project at Dryden.
But unlike the short, stiff wings found on most aircraft today, long, thin wings like those on the X-56A are susceptible to uncontrollable vibrations, called flutter, that result from the force of air flowing over them. Thin wings can also be stressed by bending forces from wind gusts and atmospheric turbulence.
“To maintain the long-term health of the structure and ride quality in a more flexible airplane, we need to actively alleviate gust loads on the airplane and suppress flutter, so gust load alleviation and active flutter suppression are two of the key technologies that NASA is working to advance,” Martin said.
MUTT is designed to address this problem by enabling engineers to practice suppressing flutter by adjusting software programs in the aircraft’s flight control computer. With MUTT, researchers also expect to learn how better to ease gust loads, which will make flexible airplanes safer when they experience in-flight turbulence.
Although the X-56A MUTT is a low-speed, subsonic, sub-scale research aircraft, aircraft that fly faster than the speed of sound also can benefit from this research. The knowledge gained about flutter and gust suppression will be used in designing the proposed supersonic X-54, an aircraft that will demonstrate sonic boom-quieting technologies that could someday alleviate the noise concerns currently preventing supersonic commercial flight over land in the United States.
Designed by Lockheed Martin’s Advanced Development Programs, known informally as the Skunk Works, the aircraft was first revealed by Aviation Week, and is intended to research active flutter suppression and gust-load alleviation technologies. The X-56A is based on Lockheed’s earlier UAV work, showing influence from the Polecat, Sentinel and DarkStar UAVs. The programme calls for the construction of two 7.5 feet (2.3 m)-long fuselages and a wingspan of 27.5 ft, with four sets of wings being constructed for flight testing.
The X-56A made its first flight on July 26, 2013, flying from Edwards Air Force Base; twenty flights were to be flown on behalf of the Air Force Research Laboratory before the aircraft would be handed over to NASA for further testing.
US Air Force Research Lab
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