Boeing X-50A Dragonfly
In June 1998 a $24 million agreement between DARPA and The Boeing Company funded a 37 month effort by the Boeing Phantom Works to design, build, and fly two technology demonstrators to assess and validate the X-50 Dragonfly Canard Rotor/Wing (CRW) advanced rotorcraft. Each contributed $12 million toward the program.
The first hover flight of the X-50A occurred on 4 December 2003, more than a year after the originally planned time frame. However, the career of the vehicle was short, because it was destroyed in a crash on 23 March 2004. After a thorough investigation, cross coupling of the rotor controls was identified as the major reason for the crash. After several modifications to the second X-50A, which had been built as a back-up vehicle, the CRW program was continued with extensive ground tests.
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| Boeing X-50A Dragonfly |
The unmanned X-50A CRW is 17.7 feet long, 6.5 feet high, and the rotor blades have a diameter of 12 feet. Powered by a conventional turbofan engine, the X-50A will use diverter valves to direct thrust to the rotor blade tips (for helicopter mode), or aft to the jet nozzle (for fixed wing mode). Dual bleed thrust will be used during transition. By directing thrust through the rotor tips, the CRW concept eliminates the need for a heavy and complex mechanical drive train, transmission and anti-torque system.
Aviation enthusiasts may have noticed that the X-50 designation was not the next in line. But Steve Bass,
Boeing’s X-50 program manager, confirms Boeing got the number out of sequence by special request. The X-50 designation is so fitting for the CRW concept 50 percent helicopter and 50 percent airplane.
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| Boeing X-50A Dragonfly |
The X-50A was powered by a single F112 turbofan engine, and the control surfaces of the vehicle consisted of fully-movable canards and a tailplane with twin endplates. The UAV was equipped with a fixed tricycle landing gear. For operation as a helicopter, the engine's exhaust was diverted to small nozzles in the rotor tips. Because of the reaction-driven rotor, no anti-torque device was needed by the CRW. As forward speed increased and significant lift was generated by the tail and canards, the engine thrust was gradually redirected to the tailpipe, until sufficient speed had been reached to stop the rotor completely and fly as a conventional fixed-wing jet. The X-50A was flown by a pilot on the ground via remote control, and there was no system installed for fully autonomous operations.
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