North American XB-70 Valkyrie - Feature from the National Museum of the USAF

The futuristic XB-70A was originally conceived in the 1950s as a high-altitude, nuclear strike bomber that could fly at Mach 3 (three times the speed of sound) -- any potential enemy would have been unable to defend against such a bomber.

By the early 1960s, however, new Surface-to-Air Missiles (SAMs) threatened the survivability of high-speed, high-altitude bombers. Less costly, nuclear-armed ICBMs (Intercontinental Ballistic Missiles) were also entering service. As a result, in 1961, the expensive B-70 bomber program was canceled before any Valkyries had been completed or flown.

Even so, the USAF bought two XB-70As to test aerodynamics, propulsion and other characteristics of large supersonic aircraft. The first XB-70A, on display here, flew in September 1964, and it achieved Mach 3 flight in October 1965. The second Valkyrie first flew in July 1965, but in June 1966, it was destroyed following an accidental mid-air collision. The third Valkyrie was not completed.

The first XB-70A airplane continued to fly and generate valuable test data in the research program until it came to the museum in 1969