The second X-50A Dragonfly demonstrator was destroyed in a crash at Yuma Proving Ground in Arizona last week, leaving Boeing and the Defense Advanced Research Projects Agency (DARPA) pondering whether the envelope-pushing program can continue.

The mishap occurred at 7:46 a.m. Mountain time April 12. There were no injuries or property damage and the cause of the crash is not yet known, Boeing told The DAILY. An accident investigation is under way.

The Dragonfly was an unmanned experimental helicopter featuring an unusually wide rotor designed to stop in flight and act as a wing, a concept known as Canard Rotor/Wing. The first X-50A prototype also was lost in a crash in March 2004 (DAILY, March 31, 2004).

"The Boeing Company and DARPA officials are in discussions regarding the future of the Dragonfly program and Canard Rotor/Wing," the company said. The program has no aircraft remaining.

Like a tiltrotor, the Dragonfly was intended to combine the operational flexibility of a rotorcraft with the speed of a fixed-wing aircraft. With the rotor stopped, lift was generated by the stopped rotor/wing, the airframe itself and canards mounted on the nose. The program had hoped to conduct its first mid-air conversion flights this year.

Boeing was developing the Dragonfly for DARPA under a $51.8 million contract. The first flights of the aircraft in late 2003 were delayed more than a year while engineers grappled with the formidable control challenges arising from the aircraft's unique design.

The program performed two brief hover tests before the March 2004 crash. After a lengthy investigation, that mishap was linked to a cross-coupling control phenomenon intrinsic to the aircraft's design. That problem was believed solved by modifications to flight software. The program finally resumed flight-testing in December 2005 using its only spare, a ground model that was modified for flight at Boeing's facility in Mesa, Ariz.

Following a 30-second "pop-up" flight in early November to build confidence, the second X-50A completed a four-minute hover flight on Dec. 2, 2005 at Yuma in which it reached an altitude of 15 feet (DAILY, Dec. 27, 2005). In subsequent flights prior to the crash the aircraft progressed as far as "slow forward flight," Boeing said.

The team had hoped to conduct two conversion flights at 120 knots airspeed later this year, during which the X-50A would have stopped its rotor while airborne. This would have been preceded by low-speed forward flights below 60 knots and "compound mode" flights between 60-120 knots in which the rotor would have been slowed somewhat but not stopped.