boeing,s a prototype for its hydrogen-fueled UAV, Phantom Eye. Designed to fly at 65,000 feet for up to four days straight, the vehicle has two 2.3-liter, four-cylinder engines, can carry 450 pounds of payload, and is scheduled to have its maiden flight in early 2011. Kochersberger compares the Phantom Eye with DARPA’s Vulture program to create a five-year battery-powered UAV that can carry more than 1,000 pounds. While Vulture is more ambitious, he says there’s probably a two- or three-year development cycle before it flies. The Phantom Eye is still on the ground, too, but closer to flying. An airplane that will stay up for several days in orbit as a communications hub is novel, Kochersberger says. “It’s a radical design.”