December 8, 2009: The U.S. Navy has been experimenting with powering lightweight UAVs with fuel cells. One of these aircraft recently stayed aloft for 26 hours. The Ion Tiger UAV is a 37 pound aircraft that carries a 9.5 pound tank of compressed hydrogen to power the fuel cell battery that runs the engine. Also carried is a five pound sensor payload (day/night vidcam).

Fuel cells are already popular with ground troops, especially those who are out on foot for days at a time. To support this, the U.S. Department of Defense ran a competition to find a better battlefield battery, and came up with three winners. The goal was to find a fuel cell that weighed less than 8.5 pounds and supplied as much battery power as the 20 pounds of currently available batteries that soldiers typically carry for a four day mission. Ion Tiger was one beneficiary of this effort.

A fuel cell uses tiny amounts of hydrogen, methanol or propane to trigger a chemical reaction that produces electricity. The fuel cell had to be small enough to hang off the soldiers webbing, and rugged and reliable enough to keep going under combat conditions. That suited a lightweight UAV as well. This type of fuel cell is already on the market, for boats or to power equipment in remote locations. The military one will cost nearly $2,000, but weight savings is one of the constant demands of combat troops.

Ground combat commanders have been asking for something like Ion Tiger, because their current UAVs, the five pound Raven, can only stay in the air 90 minutes at a time. There are some larger (Ion Tiger) class UAVs, using conventional batteries, that can only manage a few hours per flight. A hand held UAV that could stay in the air all day, or night, would be a big plus.