On display in the Research & Development Gallery at the National Museum of the U.S. Air Force. This aircraft was built in the 1980s as an experimental battlefield surveillance aircraft. It differed from the faceted surfaces of the F-117 Nighthawk and helped in the development of the B-2. Described as one of the most unstable aircraft ever flown, it required a digital fly-by-wire system to control it. Using its SLAR, it could loiter successfully at low speeds over and behind the battlefield as a stealth aircraft. Having been flown 135 times, Tacit Blue was retired in 1985.