Rotor/Wing aircraft begins flight testing

Boeing’s Canard Rotor/Wing (CRW) concept demonstrator completed its first hover flight last week at the US Army Proving Ground in Yuma, AZ.

During the flight test, the CRW advanced technology demonstrator – known as the X-50A Dragonfly – flew for about 80 seconds. It lifted off vertically from the launch site to an altitude of 12 feet above the ground, hovered and then vertically landed, commencing the flight test program.

Under joint development by Boeing and DARPA (Defense Advanced Research Projects Agency), the CRW combines the speed and range of a fixed-wing aircraft with the flexibility of rotary-wing flight. This is because the CRW’s rotor is designed not only to spin during vertical takeoffs and landings but also to stop turning during flight and convert to a fixed wing for high-speed cruise.

About a dozen flight tests are scheduled for the X-50A Dragonfly. Under the remote control of a pilot in the ground station cockpit, the vehicle will gradually perform more extensive hover flights, then forward moving rotary-wing flights, and finally a conversion to a fixed-wing flight and back again to a rotary-wing landing. Two such conversion flights are planned.

The X-50A Dragonfly vehicle is 17.7 feet long and 6.5 feet high and weighs 1,460 pounds. In addition to its 12-foot-diameter rotor/wing, it also has an 8.9-foot-span canard and an 8.1-foot-span horizontal tail. It is propelled by a conventional turbofan engine combined with Boeing’s reaction drive rotor system.

During rotary-wing flight, the engine’s exhaust is diverted by the reaction drive system through the rotor system to exit through small nozzles in the rotor tips. As forward speed increases and the canard and tail pick up the aerodynamic load of the aircraft, the exhaust is gradually diverted completely through a nozzle at the back of the aircraft, propelling it even faster forward and allowing the rotor to stop and lock into place for fixed-wing flight. The reverse then occurs for conversion back to rotary-wing flight.

The Boeing Phantom Works and DARPA have been developing the CRW concept under a 50-50 cost share agreement since May 1998.