The Lockheed XF-90 was built to meet a USAF requirement for a long-range penetration fighter (along with the McDonnell XF-88 and North American YF-93A). Developed by Clarence L. ('Kelly') Johnson's Lockheed fighter team, known in later years as the 'Skunk Works', the XF-90 combined swept-wing technology with the experience gained in producing the straightwing P-80 Shooting Star. It was intended as an almost-all-purpose fighter, capable of handling the ground-attack role in addition to its prime task of escorting bombers deep into Soviet air space. The two prototypes (46-687/688) were to be tested in a fly-off competition with the McDonnell and North American designs.

Actually, the XF-90 evolved over two years and resulted from 65 different designs created by Johnson's engineers. These included butterfly-tailed aircraft, three-engined aircraft, 'W'-winged designs and, finally, the big, tough craft that was chosen. The final XF-90 had 0.5-in (12.7-mm) rivets in the wings and weighed as much as a DC-3. Its powerplants, sadly, were twin 3,100-lb (13.79-kN) thrust Westinghouse J34-WE-11 turbojets, the same engines which simply offered too little 'push' to so many fighter designs of the period.

Still, the XF-90 reached 665 mph (1,070 km/h) at 32,100 ft (9,784 m) in level flight and could easily be pushed through the sound barrier in a shallow dive. Throughout April and May 1950, the air above Muroc Dry Lake, California, exploded in sonic booms as Lockheed test pilot Tony LeVier put the XF-90 through high-speed dive tests. LeVier dived the XF-90 to Mach 1.12 on 17 May 1950.

The XF-90 stalled at 127 mph (204 km/h), making it no easy machine to control on the approach. Its take-off performance enabled it to clear a 50-ft (15-m) obstacle in 8,625 ft (2,629 m) without the rocket-assisted take-off (RATO) units used in some tests, hardly a spectacular getaway from the ground. In the 1949 fly-off, the XF-88 came in first, the XF-90 second, and the YF-93A third, but by then the results were academic. With the September 1949 detonation of the Soviet Union's first nuclear weapon, the USAF penetration-fighter concept died.

A nuclear fate befell the second XF-90, which was rigged with instruments on the ground and destroyed in the 1952 atomic bomb tests at Frenchman's Flat, Nevada. Lockheed records indicate that the first XF-90 was shipped in 1953 to a National Advisory Committee for Aeronautics (NACA) laboratory in Cleveland, Ohio. Apparently, it was eventually broken up in tests at that NACA facility.