The XF-90 was built like no fighter before… or since. At a time when no one knew what supersonic flight would do to metal, Skunk Works chose brute force over guesswork. They forged the strongest airframe on Earth: 75S aluminum over a steel spine, the fuselage braced until it was closer to armour than aircraft. […]Lockheed XF-90 – the Nuclear-Proof Jet America Ditched
The XF-90 was built like no fighter before… or since. At a time when no one knew what supersonic flight would do to metal, Skunk Works chose brute force over guesswork. They forged the strongest airframe on Earth: 75S aluminum over a steel spine, the fuselage braced until it was closer to armour than aircraft. […]