The North American XB-70 Valkyrie was a “technical marvel” of the 1950s—a Mach 3, 70,000-foot nuclear bomber designed to replace the B-52. -It used a “revolutionary” principle called “compression lift ...

The North American XB-70 Valkyrie embodied a once-dominant creed: outrun defenses at Mach 3 and 70,000 feet. -The prototype proved the physics—compression-lift wingtips, hot-structure skins, 172,000 ...