Insitu has become the latest unmanned aircraft manufacturer to fly a fuel-cell powerplant in one of its designs. A 1,500-watt (2 hp) fuel cell produced by United Technologies and a hydrogen fueling system developed by the Naval Research Laboratory were integrated into a ScanEagle UAV, which met its performance targets on a 2.5-hr. test flight.

Insitu says it will conduct a fuel-cell test flight in its larger Integrator UAV later this year, in collaboration with the Air Force Research Laboratory (AFRL). Lockheed Martin, meanwhile, is developing the fuel-cell version of its hand-launched Desert Hawk under AFRL’s Small Unmanned Renewable Energy Long Endurance Vehicle (SURGE-V) program. The Desert Hawk Extended Endurance Range can fly for up to 8 hr.

AeroVironment has flown a version of its Puma AE small UAV powered by a compressed-hydrogen fuel cell and battery, while Lockheed Martin Skunk Works has developed the slightly larger Stalker Extreme Endurance with a propane fuel cell and battery. Both Puma and Stalker are used by U.S. special operations forces.