This paper details the Naval Research Laboratory’s development of hydrogenfuel cell propulsion systems for unmanned aircraft and the Experimental FuelCell (XFC) Unmanned Aerial System (UAS), the first tactical unmanned airvehicle to incorporate this novel propulsion system. Fuel cell propulsionmaximizes the advantages of electric aircraft propulsion including inherentstealth, easy starting, simple operation and maintenance, while also enablinglong endurance and payload mass fractions comparable to internal combustionpowered air vehicles. NRL fuel cell technology has been incorporated into theXFC to demonstrate the feasibility of a long endurance, self-deploying, aircraft.XFC can self-launch vertically from its 18 in. diameter by 8 ft. storage containerusing its Electric Assisted Takeoff (EATO) system. Its non-hybridized ProtonExchange Membrane (PEM) fuel cell power plant can power the aircraft andEO/IR payload for a flight endurance of greater than 6 hrs, as compared to the 1to 2 hours under battery power. The increased flight endurance and payloadcapacity enables a much wider range of tactical missions for Small UAS. Inaddition, the XFC is being adapted for launch from a submerged submarine.NRL propulsion technology development, the XFC air vehicle development, labtests, flight tests, and details of key subsystems are covered in this paper.
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