If you can imagine a plane that can stay in flight for years at a time and refuel itself autonomously, then you're thinking like a government agent (or at least a science fiction writer).
Last week, the Defense Advanced Research Projects Agency (DARPA), the research and development arm of the U.S. Department of Defense, began soliciting bids from the private sector to design a plane that can remain aloft for five years with a 99 percent probability.
Called the Vulture Air Vehicle Program, possibly after the vulture's ability to sail on thermal streams, the project "will research and develop technologies and systems which will enable the military to deliver and maintain a 1,000-pound airborne payload for an uninterrupted period exceeding five years," according to a statement from DARPA released May 16.
Vulture's technical challenges include "environmental energy collection, high specific energy storage, extremely efficient propulsion systems, precision robotic refueling, autonomous material transfer, extremely efficient vehicle structural design, and mitigation of environmentally induced loads," according to DARPA.
Translated, the project calls for planes powered from solar or fuel cells, among other options. But DARPA said it's specifically not interested in planes that would use radioactive energy or forms of buoyant flight, i.e., blimps.
The government blog Tech Insider speculated about a few potential contenders, including AeroEnvironment, a Monrovia, Calif.-based maker of electric-powered planes. Scaled Composites, the Mojave, Calif.-based company that's working with Richard Branson on his commercial spaceflight venture, might also be an option given that its owner, aerospace engineer Burt Rutan, designed the Voyager plan that flew around the world without refueling in the '80s.
DARPA didn't specify the mission of Vulture, and a representative wasn't immediately available for comment. But the agency said that it will be accept bids for the project at a Vulture information day in Arlington, Va., on June 7.
"It is envisioned that this program will, at a minimum, develop and demonstrate advanced reliability technologies for air vehicles," DARPA says. "Other advanced technologies may also be developed and demonstrated depending upon the nature of the architectures proposed by offerers."