Photos: A brief history of stealth aircraft

Lockheed's DarkStar was an ill-fated early attempt at a reconnaissance drone. The first prototype crashed in 1996 on just its second flight; a second flew only five times in 1998-99 before the program was cancelled. The stealth-influenced unmanned aerial vehicle was intended to provide recon in highly defended areas, flying above 45,000 feet at subsonic speeds and for more than 8 hours at a stretch.

Photo by NASA Dryden Flight Research Center