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Georgia Tech researchers start up the fuel-cell-powered aircraft before a test flight at the Atlanta Dragway. Photo by Gary Meek |
Other groups have flown fuel-cell-powered drones, but the aircraft were smaller or relied on liquid hydrogen. (Compressed liquid hydrogen, which is cheaper and easier to work with, is the form of hydrogen the auto industry seems to prefer.) And smaller drones have no landing gear and must be manually launched. The Georgia Tech drone, on the other hand, operates like a full-sized aircraft and needs no batteries or booster for take-off.
The Georgia Tech UAV operates solely on the 500 W from the fuel cell (about 1% of the power needed to power the Toyota Prius hybrid car). For the powerplant, the team extensively modified a commercial fuel-cell stack with added hydrogen delivery and refueling systems, and thermal and air-management systems. They also included a data-acquisition suite so the aircraft could transmit data while airborne.
Space limitations were a challenge in building the craft because the plane's fuselage measures only 45-in. long, a maximum of 9.75-in. wide, and 7.25-in. tall. The team applied a little off-the-shelf ingenuity and incorporated a pump from a liquid-cooled computer. And one of the craft's hydrogen tanks started life as a component in a paintball gun. The team also had to keep the plane light. For example, they use carbon foam for the fuel cell's radiator. To keep drag low, the design includes an inverted V-tail, a rear-mounted propeller, and slender, 22-in.-long, wings.