The downing of Francis Gary Powers' U2 didn't "cause a shift from manned bombers to ballistic missiles," it illustrated something the US knew all along, that anti-aircraft missiles would someday be able to take out very high-flying aircraft. Ballistic missiles for nuclear weapons delivery had been a dream for both sides for years, and by the early 1960s had become practical, which the Valkyrie was not.

Still, it is one of the most beautiful aircraft ever to fly.