This aircraft was built to meet requirements that seemed impossible. ✈️ In the 1960s, North American Aviation solved an impossible engineering problem with the XB-70 Valkyrie. Instead of fighting air resistance at Mach 3, engineers designed the aircraft to ride its own shockwave; a concept called compression lift. By folding its wingtips down 65 degrees in flight, the Valkyrie trapped high-pressure air beneath its delta wing, generating 30% of its lift for free. It remains one of the largest and