Boeingunveiled its hydrogen-poweredPhantom Eye unmanned airborne system during a ceremony inSt. Louis. The demonstrator, which will stay aloft at 65,000 feet for up to four days, is powered by two 2-liter, four-cylinder engines that provide 150 horsepower each. It has a 150-foot wingspan, will cruise at approximately 150 knots and can carry up to a 450-pound payload.
Eventually,they're going to build one that only has to come down for an engine overhaul.