North American XF-108
When the Air Force wanted a long-range, high-speed interceptor to defeat incoming Soviet supersonic bombers, North American Aviation came up with the XF-108. The “Rapier” design shared engine technology with the XB-70 Valkyrie supersonic bomber prototype and would have reached speeds of Mach 3, and engage bomber formations 100 miles away. However, the Soviet Union shifted their focus to missiles instead of fleets of nuclear-armed bombers and the XF-108 project was cancelled before any actual aircraft could be built.
