Orion HALL UAV mock-up unveiled Bill Sweetman Jane's International Defence Review Aerospace & Technology Editor Farnborough Aurora Flight Sciences has unveiled a full-scale mock-up of a hydrogen-fuelled long-endurance unmanned aerial vehicle (UAV) that it is developing in collaboration with Boeing's Phantom Works. Named the Orion HALL (High Altitude, Long Loiter), it is linked to the UAV project that was disclosed to Jane's in early July by George Muellner, Phantom Works' president of advanced programmes. Orion HALL is described as a small-payload vehicle (180 kg) with a four-day endurance, while Boeing's planned High-Altitude, Long-Endurance (HALE) vehicle would have a 10-day endurance. The first vehicle is expected to fly in 2008. The project is funded by the US Army's Space and Missile Defense Command (SMDC) as a platform for high-altitude sensor tests and a contract for two vehicles is expected shortly. The aircraft will be operated for SMDC by Mississippi State University's Raspet Flight Research Laboratory. It is being built by Virginia-based Aurora in the company's Columbus, Mississippi, facility. Details of the new vehicle have not been formally released, but it is a conventional design with tail aft, tractor propeller, a wingspan around 35 m and a single 5 m-diameter, four-bladed propeller. The large-diameter body houses the low-density liquid hydrogen fuel. The forward segment of the body resembles a classic National Advisory Committee for Aeronautics cowling for a radial air-cooled piston engine, but probably houses a heat exchanger in which the hydrogen expands to a gas via a turbine, producing additional power before being fed into a conventional engine. I know, I know....hydrogen fuel cells can't work...or so I've been told by some posters here.