The U.S. Army Air Force, in the years following World War II, issued a requirement for a “penetrating escort” jet that would accompany strategic bombers deep into Soviet territory. This ambitious requirement fostered the development of the Lockheed XF-90, the jet that would later prove its resilience in several nuclear tests.
The XF-90 was an experimental plane designed by Kelly Johnson’s team at the Lockheed Skunk Works. Initially, Johnson had considered a delta-wing configuration but opted for swept wings to delay shockwave formation at high speed. The XF-90 featured a needle-nose design with 35-degree swept wings and the Air Force’s first afterburners, which allowed bursts of additional speed at the expense of fuel efficiency. The jet was armed with six 20-millimeter M39 cannons; wingtip fuel pods extended its range to a projected 2,300 miles.
The only thing that indicated robust construction in the XF-90 was due to the use of high-strength 75T aluminum alloy, making it as tough as a “bridge girder.” At this, it became one of the heaviest single-seat fighters of its time, with the structural strength capable of withstanding a dozen times the force of gravity. Despite such impressive durability, the XF-90 had difficulties because of underpowered Westinghouse J34 turbojets that left it slower than the Air Force’s F-86 Sabre.
First flown by test pilot Tony Levier on June 3, 1949, the XF-90s were mediocre in their takeoff and landing lengths but managed to achieve supersonic in shallow dives at Mach 1.12. After losing a fly-off with the McDonnell Douglas XF-88 Voodoo, though, the project was abandoned in favor of other demands on the funding set aside for tactical air power in the Korean War.
Operational deficiencies notwithstanding, the XF-90 did achieve some fame as a result of its appearance in the comic book series Blackhawks. The reality of things was anything but so exciting, though. The prototype, XF-90 46-687, was stress tested to destruction at the NACA facility in Cleveland, Ohio, while the second prototype, XF-90 46-688, fared little better.
In 1952, the Pentagon conducted a series of nuclear tests on the XF-90 at the Nevada Proving Ground. On April 15, a 1-kiloton nuclear bomb exploded half a mile from the jet, which sustained cracks but otherwise remained intact. A week later, a 33-kiloton bomb further damaged the aircraft. Finally, a 19-kiloton blast on May 1 severed its tail and landing gear. Under such extreme conditions, the sturdy frame of the XF-90 held on.
The irradiated hulk of the XF-90 was re-discovered in the late 1980s by scientist Robert Friedrich, who championed its preservation. In 2001, contractors cleaned the jet of its radioactive residue and broke it down into sections, hauling it to the U.S. Air Force Museum in Dayton, Ohio. The XF-90 remains warehoused there, retained in its nuke-scorched state.
Although it never found operational success, it left behind experience in jet technology development. The sixth-generation stealth jet that the Air Force is now conceptualizing returns to that original concept of “Penetrating Counter-Air” fighter-showing how strong the legacy of the groundbreaking design of the XF-90 will continue to be.