The XB-70 Valkyrie Could Reach Mach 3 at 70,000 Feet With 6 Engines — Friction Heated Its Skin to 600°F

The XB-70 Valkyrie Could Reach Mach 3 at 70,000 Feet With 6 Engines — Friction Heated Its Skin to 600°F

The Air Force commissioned the XB-70 Valkyrie in the late 1950s to drop nuclear bombs from Mach 3 at 70,000 feet. North American Aviation built only two prototypes. Six General Electric turbojets generated 600°F skin temperatures during Mach 3 flight. The Valkyrie used stainless steel honeycomb and titanium construction. The first supersonic flight came in October 1964. On June 8, 1966, during an unauthorized photoshoot for General Electric, an …