UAVs

The US Georgia Institute of Technology (GeorgiaTech) has flown a 6.7m (22ft)-wingspan, 500W gaseous hydrogen fuel-cell-powered unmanned air vehicle to highlight the capabilities of fuel cells and low-cost UAVs.

The UAV's power system is a proton exchange membrane fuel cell, fed with compressed gaseous hydrogen. Adam Broughton, research engineer at Georgia Tech's aerospace systems design laboratory, says: "Five hundred watts is plenty of power for a light bulb, but not for the propulsion system of an aircraft this size."

Fuel cells have also been used by US company Aerovironment, which in 2005 used the technology to power the eight electric engines of its 15.2m-wingspan, liquid-hydrogen-fuelled, high-altitude, long-endurance Global Observer UAV demonstrator. The testbed is a one-third-scale version of a proposed 45-61m wingspan hybrid-fuel cell and solar-powered UAV.

Aerovironment hopes the full-scale version could fly for more than a week with a 4,530kg (10,000lb) payload. The vehicle would be used for NASA's planned ultra-long-endurance, high-altitude UAV research programme.