Though not an Autobot or Decepticon transformer in the popular movie series sense of the word, Boeing and NASA’s remotely piloted X-48C aircraft successfully flew for the first time on Aug. 7, 2012, from NASA’s Dryden Flight Research Center at Edwards Air Force Base in California's Mojave Desert.
The new X-48C model was transformed, or "modified" in engineering lingo, from the X-48B Blended Wing Body aircraft, which flew 92 flights at NASA Dryden between 2007 and 2010. The X-48C will be used to evaluate the low-speed stability and control of a low-noise version of a notional, future Hybrid Wing Body (HWB) aircraft design. The HWB design stems from concept studies being conducted by NASA's Environmentally Responsible Aviation project of future potential aircraft designs 20 years from now.
Primary changes to the C-model from the B-model were geared to transform it to an airframe that does a better job shielding engine noise from the ground – a potential improvement for communities around airports. External modifications included relocating the wingtip winglets inboard next to the engines, effectively turning them into twin tails. The aft deck of the aircraft was also extended about two feet to the rear. Finally, the project team replaced the X-48B’s three 50-pound-thrust jet engines with two 89-pound-thrust engines.
The X-48C retains most of the physical dimensions of the B-model, with a wingspan just longer than 20 feet and a weight of about 500 pounds. The aircraft has an estimated top speed of about 140 mph, and a maximum altitude of 10,000 feet.
Because handling qualities of the X-48C will be different from those of the X-48B, the project team developed flight control system software modifications, including flight control limiters to keep the airplane flying within a safe flight envelope. This will enable a stronger and safer prototype flight control system suitable for future full-scale commercial hybrid or blended wing aircraft.
Additionally, the upcoming flight experiments with the X-48C will help researchers further develop methods to validate the design’s aerodynamics and control laws, including a goal of reducing aerodynamic drag through engine yaw control tests.
During the planned second block of flight testing this fall, NASA will test engine yaw control software incorporated in the X-48C’s flight computer. This research will use asymmetric engine thrust to create yaw, or nose left or right movements, for trim and for relatively slow maneuvers.
NASA's Aeronautics Research Mission Directorate and Boeing are funding the X-48 technology demonstration research effort, which supports NASA’s goals of reduced fuel burn, emissions and noise. The aircraft is designed by the Boeing Co. and built by Cranfield Aerospace Ltd. of the United Kingdom. The Air Force Research Laboratory, Dayton, Ohio, is also a member of the project team.
NASA Dryden Public Affairs