DARPA's Vulture program aims to build an unmanned vehicle that could stay up for five years. That's still quite a stretch, considering that the current world record-holder, the Zephyr built by Qinetq, can stay aloft only for days.
Last month the U.K.-based company's latest model, the Zephyr 7, shattered its own endurance record by flying non-stop for two weeks and 22 minutes. The claim is still pending official recognition by the Fédération Aéronautique Internationale. Ya gotta love a record-setting aircraft that's launched by hand.