| X-50 Dragonfly | |
|---|---|
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| General information | |
| Type | ExperimentalUAVrotorcraft |
| Manufacturer | Boeing |
| Status | Canceled |
| Primary user | DARPA |
| Number built | 2 |
| History | |
| First flight | 24 November 2003 |
TheBoeing X-50A Dragonfly, formerly known as theCanard Rotor/Wing Demonstrator, was aVTOLrotor wing experimentalunmanned aerial vehicle that was developed byBoeing andDARPA to demonstrate the principle that a helicopter'srotor could be stopped in flight and act as a fixed wing, enabling it to transition betweenfixed-wing androtary-wing flight.
The X-50A built upon the work of theSikorsky S-72 X-Wing program of the 1980s by designing the vehicle as a multi-mode aircraft from the ground up. The X-50A was one of two projects funded by DARPA in its "Heliplane" program.[1][2]
Neither of the two prototype aircraft ever successfully transitioned to full forward flight. DARPA withdrew funding for the X-50 program in late 2006 due to inherent design flaws.[1]
Boeing initially proposed using the CRW configuration to fill a requirement for a VTOL aircraft suitable for escorting theV-22tiltrotor.
The X-50A was a joint program between Boeing and DARPA, with each paying for half the development costs. The X-50A was powered by a single conventionalturbofan engine. For rotary-wing mode, the engine's exhaust was diverted to nozzles in the tips of the rotor blades. When the aircraft transitioned to full forward flight, the engine exhaust was directed through a nozzle at the rear of the aircraft and the rotor was locked into a fixed position and functioned as a conventional wing.[1] Two proof-of-concept aircraft were built as part of the program. The X-50A's maiden flight took place on 24 November 2003.
The X-50 had a"canard" foreplane as well as a conventional tailplane, allowing both to contribute lift during forward flight and to offload the main rotor wing.
For vertical take-off, hovering, low-speed flight, and vertical landing, the main rotor wing was driven bytip jets, by directing the exhaust from ajet engine through thrust nozzles in the rotor tips. Because the rotor is driven directly by jet thrust, there is no need for atail rotor to controltorque as in a conventional helicopter.
For high-speed forward flight, the exhaust is redirected through an ordinary jet nozzle and the rotor wing is stopped and held in a fixed position, as in a conventional airplane.
During the third flight of the prototype X-50A, on 23 March 2004, the vehicle crashed, as a result of cross-coupling in the controls.[1]
A second, improved prototype ("Ship 2") was then built. On its sixth of 11 planned test flights, Ship 2 was completely destroyed in a crash at theYuma Proving Ground on April 12, 2006. Subsequent investigation revealed that the aircraft'sfuselage was subject to an aerodynamicpitching moment of extreme sensitivity. Both airspeed and rotor wake would produce a nose-up pitching motion that was greater than the flight controls could compensate for.[1]
Neither aircraft was able to achieve transition to full forward flight mode during the portions of the test flight program that were completed. In September, 2006, DARPA recognized the inherent design flaws and withdrew funding for the program.[1]
General characteristics
Performance