What went down.
Watch an XB-70 Valkyrie Mach 3 Bomber Perform an Emergency Landing
The B-70 Valkyrie, with a planned cruise speed of Mach 3 and operating altitude of 70,000 feet, was to be the ultimate high-altitude, high-speed manned strategic bomber. Events, however, would cause it to play a far different role in the history of aviation.
By the early 1960s in fact, new Surface-to-Air Missiles (SAMs) threatened the survivability of high-speed, high-altitude bombers, while 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-70 aircraft to test aerodynamics, propulsion and other characteristics of large supersonic aircraft. The first XB-70A (Air Vehicle 1 or AV 1) flew in September 1964, and it achieved Mach 3 flight in October 1965. The second Valkyrie (AV 2) first flew in July 1965, but in June 1966, it was destroyed following an accidental mid-air collision. The third Valkyrie (AV 3) was not completed.