In November his company unveiled a mid-altitude UAV that burns diesel fuel and will stay aloft for five days. “You’ve had a convergence of technology at the same time you’ve had a real need emerge,” says John Langford, chairman and president of Aurora Flight Sciences, which specializes in UAVs.
Advances in solar cells from the green energy industry, more efficient batteries and fuel cells, more durable engine parts, and new aerodynamic designs may now offer the tools to keep an airplane aloft for years. The program ended in 2003, when unpredictable winds tore up Helios, a prototype built for the program by a pioneering company in unmanned flight, AeroVironment. In the 1990s, NASA sought to develop a fleet of such UAVs for environmental research. An autopilot flies a preplanned route while ground-based operators make sure it stays on course. They fly high and slow without refueling, and shrug off maintenance schedules and ground crews. Their spindly, giant wings push the limits of aerodynamic efficiency. SolarEagle and similar high-altitude, long-endurance prototypes are stretching our notions of airplanes. Louis and near Seattle, combine the durability of satellites with the lower cost and flexibility of airplanes, and, of course, meet the central challenge from DARPA: fly for five years without landing. Everyone involved hopes to see SolarEagle, now under construction in St. DARPA has now committed $89 million to the prototype. military’s group that funds concepts bordering on the impossible. In September 2010, the design became the winner of the Vulture II program, a competition run by the Defense Advanced Research Projects Agency (DARPA), the U.S. Such endurance will require solar cells and an energy storage system so light and efficient that they have not yet been fully developed. SolarEagle will draw its power from the sun, with solar panels carpeting a wingspan almost twice that of a 747. Energy, then, becomes the limiting factor. “We don’t want to take any unnecessary weight to altitude,” explains Wilke, flight test lead for SolarEagle, underscoring the key challenge of keeping an airplane in the sky as long as possible: Make it light so it needs very little energy to stay aloft. They’re so unconcerned about seeing the airplane again, they may have it jettison its wheels after takeoff. Ultimately they want it to stay up for five years, long enough to outlast a presidential administration and who knows how many generations of iPods. Initially, the two engineers from Boeing’s Phantom Works want the unmanned aerial vehicle (UAV), named SolarEagle, to fly at twice the altitude of cruising airliners for 30 days straight. AT SOME POINT in early 2014, Pat O’Neil and Carol Wilke expect to launch a new airplane they hope they will never see again-at least not for a long time.
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