>>5550871 (lb)

XB-70 Valkyrie, taught NASA everything they needed about "compression lift." Only two ever built, one crashed after collision with chase plane, surviving airframe at USAF Museum Wright-Patterson AFB, Ohio. XB-70 was supposed to fly full afterburner take-off to landing for high-speed high-altitude missions into Soviet airspace at Mach 3. Outer portions of wings fold down during flight for stability. Program cancelled as new Soviet defenses changed tactics to low-altitude missions the B-52 could handle. Valkyrie was years before Concorde