9. XB-70 Valkyrie 2,000mph
Photo: nasa
The XB-70 Valkyrie is a very interesting plane, to say the least. It was a prototype built in 1964 that featured six engines that could push it to a record 2,000mph while traveling at a mind-boggling altitude of 70,000 feet. Because of this extreme altitude, the Valkyrie was virtually immune to interceptor aircraft.