The U.S. Department of Defense and the Boeing Co. say they will continue development of a revolutionary helicopter despite the crash of an unmanned prototype in March.
Investigators have reached preliminary conclusions about the cause of the accident, and the developers said they will proceed with flight simulations and wind tunnel testing in hopes of eventually resuming test flights, said Jan Walker, spokeswoman for the Defense Advanced Research Projects Agency, the Pentagon’s research and development department.
The agency and Boeing are funding the $ 40 million project called the X-50A Dragonfly. It is a canard rotor/wing aircraft equipped with a two-bladed rotor that functions as a helicopter rotor and as a fixed wing.
An experimental prototype crashed during a test flight on March 23 at the U.S. Army Proving Ground in Yuma. Walker said the aircraft was "extensively damaged," but she did not say if any parts of the aircraft were salvageable. There were no injuries because the craft was being remotely controlled from the ground.
According to the interim report, the "mishap" was most likely caused by a "combination of interactions" among mechanical parts, pilot inputs "and possibly other unknown factors" that caused the aircraft to become unstable while in flight. Control mechanisms on the machine were "overwhelmed," resulting in the accident, the report said.
"Basically, too many things were going on at once for the craft to process," said Boeing spokesman Glen Golightly, who added that Boeing engineers "learned a lot from that."
Walker said the simulations and wind-tunnel results may be used to make design changes before flights are resumed with a second prototype. She had no timetable for resumption of flights.
The 17-foot-long plane has an unusual design developed at Boeing’s Mesa works that allows it to take off and land vertically like a helicopter and perform as a conventional airplane in flight.
It is powered by a single turbofan jet engine. During rotary flight, the engine’s exhaust is diverted into the two main blades and exits through small nozzles in the rotor tips, causing the blades to spin rapidly. As the machine becomes airborne the exhaust is diverted through a nozzle at the back of the plane, propelling it forward.
Meanwhile, the spinning rotor comes to a stop and is locked in place, functioning as a fixed wing to give the vehicle lift.
Also a large horizontal tail and a forward canard provide added lift.
When the vehicle is ready to land, the jet exhaust is redirected through the blades, and it functions again as a helicopter.
The Dragonfly is controlled from the ground by a pilot who sits in a simulated cockpit with instrument displays in front.
Commands are relayed to the aircraft in much the same manner as a radiocontrolled model airplane.
Despite the setback, Boeing officials believe the technology has potential for a wide range of military and civilian uses including unmanned aerial reconnaissance.