Nukes vs. Airplanes
Between the F-80 and the F-104, a supersonic pioneer fought the Cold War…in its own way.
(Lockheed Martin)
By Jorge and Karen Escalona
Air & Space Magazine | Subscribe
On April 22, 1952, dozens of journalists and approximately 2,000 military personnel watched as a 31-kiloton nuclear bomb exploded above the Nevada Proving Ground. Operation Tumbler-Snapper, as the series of atmospheric tests was called, was designed to evaluate the vulnerability of parked aircraft to an atomic bomb blast. Among the aircraft gathered there was one of the hottest-looking fighters ever built: Lockheed's XF-90.
From This Story
Considered one of the most appealing fighters ever built, Lockheed's XF-90 enjoys a first-rate reputation with aviation enthusiasts — something of a surprise, given that only two were ever built. While researching and writing "Lockheed's Missing Link" for our June/July 2008 issue, authors Jorge and Karen Escalona compiled rare footage of the XF-90 at Muroc (now Edwards) Air Force Base in California in 1949. The footage, which has no sound, includes scenes of the first XF-90 prototype being trucked to Muroc, and a brief glimpse of engineers attaching ribbonlike strips to the wing to gauge airflow patterns during preflight tests. Also seen are ground crews affixing Jet-Assisted Takeoff (JATO) canisters to the aircraft (to provide additional thrust) before Tony LeVier, Lockheed's chief test pilot, takes it for a spin. The Escalonas write: "The XF-90's dashing good looks earned it movie-star status throughout the 1950s—far beyond its operational life—attracting readers and advertisers to prominent aviation periodicals and comic books of the time." Video: Courtesy Jorge and Karen Escalona
Video: Test Flying the XF-90
In the spring of 1952, the U.S. Defense Nuclear Agency conducted a series of atomic bomb drops and tower shots at the Nevada Proving Ground, code-named "Operation Tumbler Snapper." One of Tumbler-Snapper's objectives was to see how soldiers and military equipment—including one of only two Lockheed XF-90 fighters ever built—reacted to the detonation. Jet aircraft (including the XF-90 and some F-47s) were seen to be less damaged by the atomic blast than were the bombers (a B-45, a B-29, and some B-17s). This excerpt from a contemporary U.S. Air Force documentary about the Tumbler-Snapper program focuses on the airplane testing. Source: Internet Archive/ US Dept. of Energy
Video: Operation Tumbler-Snapper
As a "penetration fighter," the XF-90 was meant to do it all: destroy ground targets, withstand anti-aircraft fire, outrun enemy fighters, and escort bombers to their targets. It ended up as atomic bomb test fodder. (Lockheed Martin)
"The important thing was that the -90 liked to fly," Lockheed's chief test pilot Tony LeVier wrote in 1954. "That's always the mark of a good airplane." (Courtesy of R. Puffer, Edwards AFB)
The needle-nose fighter followed Lockheed's F-80 Shooting Star, the first U.S. jet fighter to see action, and was an important precursor to the "missile with a man in it," the F-104 Starfighter. And though only two were built, the XF-90's dashing good looks earned it movie-star status throughout the 1950s—far beyond its operational life—attracting readers and advertisers to prominent aviation periodicals and comic books of the time. As a single-engine F-90B, it made a splashy cover for the September 1953 comic book Blackhawk. Thereafter, a generation of young Boomers dazzled by futuristic aviation technology awaited each new adventure of American pilot Blackhawk, his buddy Chuck, and their coalition of international fighter jocks manning a fleet of six sleek F-90Bs in the quest to take down the "Red Tide" thugs of the atomic age.
The F-90 was the first U.S.-built, swept-wing jet to use afterburners as standard equipment and have wingtip fuel tanks and a fully adjustable fin and stabilizers. Fowler flaps and leading-edge slats improved airflow over the wings, making the F-90 one of the pioneers in 35-degree swept-wing technology. In tests, the hot rod exceeded Mach 1 fifteen times.
So how did such a capable aircraft, one that so captured the public's imagination, become atomic bomb test fodder?
After World War II, the U.S. Army Air Forces needed a "penetration fighter," capable of escorting bombers to and from their targets. The early jet fighters had been far from perfect, and their notorious fuel consumption decreased their range. In 1945, the AAF issued a request for a fighter with a combat radius of about 900 miles. Competing for the contract against McDonnell's XP-88A and North American's XP-86C, Lockheed's team, headed by Clarence "Kelly" Johnson and Willis Hawkins, went through 65 versions before settling on the swept-wing design of the XP-90. (In 1948, the P designation, for "pursuit," was changed to F, for "fighter.")
Johnson pushed the group to produce two twin-engine prototypes, whose appearance inspired the team to coin the nickname Big Broad-Breasted Turkey. "Its front view with the broad fuselage and side inlet ducts gave it the broad-breasted look," says Jim Beach, the engineer who pioneered the XF-90's canopy actuation and ejection system. "Jim Pray, the windshield designer, dubbed it a 'turkey' due to its wimpy engines."
Testing of the "wimpy" engines began on the ground at Burbank, California, but the first XF-90 was trucked to the North Base of Muroc Air Force Base, now Edwards Air Force Base, in 1949 for flight testing by Tony LeVier, Lockheed's chief test pilot.
Lockheed assigned flight test engineer Ernest Joiner to the project. "Very little was known at that time about what happened to an airplane when it exceeded the speed of sound," Joiner recalls. "There were all kinds of weird ideas that the airplane would be subjected to very high structural loads. This lack of information contributed to the XF-90 being the strongest airplane anyone had ever seen. Of course, the sound barrier had been broken by Chuck Yeager in the X-1 research aircraft in October 1947, but [that didn't happen] in time to have much influence on the design of the XF-90."
It fell to Chuck Buzzetti, a research engineer in the flight test organization, to evaluate the strain gauges used to measure the wing loads on the heavy aircraft. "The main I-beam of the F-90 resembled a bridge girder," says Buzzetti.
Due, in part, to its aluminum skin—four times more stress-resistant than the standard alloy of the day, and a feature that enabled the aircraft to withstand 12 Gs—the single-seat fighter weighed as much as a DC-3, and was almost 71 percent heavier than an F-86, so its Westinghouse engines were seriously underpowered. The team could only hope the airplane would survive its test flight.
Single Page Previous Page 1 of 3 Next 1 2 3