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The Grumman XF10F-1 Jaguar

A swing-wing shambles

The Grumman XF10F-1 Jaguar fighter of the 1950s would have been a brilliant mistake if the thinking behind it had been brilliant.

Perhaps the thinking was brilliant, but there was simply too much of it as engineers pursued conflicting goals to design and fly the XF10F-1. What began as a modest concept, a swept-wing derivative of the F9F-2 Panther, evolved into a complex and troubled project that kept running afoul of changing requirements, to say nothing of the jet engine problems that almost crippled the U.S. Navy during the period.


The XF10F-1 taking off. Note the small canard flight surface at the tip of the fairing of the T-tail. This was controlled by the pilot. Its incidence is pushing the front of the larger flight surface of the stabilator down, causing the aircraft to pitch up for take off. In practice, the system could never be made to work safely or effectively. Robert F. Dorr collection

The result was an aircraft that was heavy, obese, underpowered, and nothing like the sleek and graceful Jaguar painted on its fuselage. The XF10F-1 was, in a manner of speaking, too brilliant, with the project team under Gordon Israel repeatedly stymied in efforts to achieve the twin goals of transonic speed and good, low-speed handling qualities.

Development began in November 1946. It was the dawn of the jet age. Had it been developed quickly, the XF10F-1 would have been the first Navy fighter with swept wings. In 1947, the Navy ordered two prototypes and scheduled flight trials to begin in August 1949.

The maiden-flight target date was unduly ambitious. In “Grumman Aircraft Since 1929” (London: Putnam, 1989), Rene J. Francillon wrote that progress with the XF10F-1 design was “complicated by a steady stream of Navy dictated changes and demands for radar, increased range, heavier armament, etc.” On top of that, in July 1949 Grumman proposed that the new aircraft should have variable-sweep wings.


Constant Change

This was a radical change and a revolutionary idea – a wing that could slide forward to provide sufficient lift for take off, and could sweep back at a sharper angle for high-speed flight. At the time, Bell Aircraft Corporation was examining the never-completed Messerschmitt P.1101 jet research aircraft, which had wings whose sweep could be changed by a technician on the ground but not in flight. Bell developed the X-5 research aircraft, whose wing sweep could be changed by the pilot while the plane was in the air. The first X-5 took to the air only months ahead of the XF10F-1, but the latter won the distinction of being the first true fighter with variable geometry wings.


An XF10F-1 Jaguar during a test flight. The variable-sweep wing, mounted high, the Navy’s demand for a larger diameter radar dish, and the cheek inlets and ducting for the disastrous J40 engine all helped dictate a less-than-svelte design. U.S. Navy photo

Corwin “Corky” Meyer took the XF10F-1 aloft for its first flight on May 19, 1952 at Edwards Air Force Base, Calif. As it turned out, Meyer would be the only pilot to ever fly it. By then, the Jaguar had joined a long roster of Navy aircraft whose performance was undermined by the disappointing, 6,800-pound thrust Westinghouse J40 turbojet, the engine that single-handedly wrecked U.S. naval aviation of the day. While Meyer famously told friends that he loved the XF10F-1 because it was nearly impossible to fly – he thrived on challenge – the F3H Demon, F4D Skyray and A3D Skywarrior were being redesigned to accommodate alternatives to the ill-fated J40.

No such luck befell the Jaguar. No alternate engine appeared practical. Moreover, although the XF10F-1 was intended to fly with an afterburner, the J40-WE-8 afterburning version of the engine couldn’t pass its required reliability tests until 1952, so the Jaguar never acquired that feature.

While tests with the first XF10F-1 proceeded with slow deliberation, the aircraft was kept out of the public eye. Except for a blurred, illicit photo taken through a fence that appeared in the magazine Royal Air Force Flying Review, the public never saw photos of the XF10F-1 until many years after the plane was history. In the 1950s, two teen-aged boys demanded accountability from their government by writing letters to the Navy. The young aviation buffs wanted to know why the Navy release wouldn’t release photos of the XF10F-1.

The youngsters received a reply from the Navy’s Chief of Information in the Pentagon. No copy has survived, but, as remembered today, the gist of the Navy’s response to Gary Kuhn and this writer was: Government is complicated and officials can’t always cater to youthful airplane buffs. “Essentially, they said, ‘Go away, little kid,'” said Kuhn, today a retired university professor.


XF10F-1 Production Plans

The Navy placed orders for 123 F10F-1 fighters and eight F10F-1P reconnaissance versions of the Jaguar. The orders may have been part of a hasty spending spree that was touched off by a stunning surprise – the success of the Soviet MiG-15 in Korea. Construction of a second XF10F-1 prototype proceeded normally and plans for a full-scale production line were made.

The Jaguar’s so-called “swing wing” was never a problem. Meyer wrote that the swing-wing feature worked flawlessly on all but one of the 32 flights made by the XF10F-1. Hal Andrews, a Bureau of Aeronautics engineer, said the wing was “surprisingly reliable considering that the Navy had never had anything like it before.” The variable geometry wing achieved its purpose: it could be swept back for high-speed combat performance and swept forward for low-speed operations around an aircraft carrier. The wing spanned 51 feet in the “straight” position and 37 feet when swept back.

Grumman XF10F-1 Jaguar

The Grumman XF10F-1 Jaguar’s variable-sweep wing, which was expected to be the riskiest aspect of the design, performed almost flawlessly. It was the innovative flying tail and conventional wing slats that caused many of its problems. U.S. Navy photo

The variable geometry wing became something of a fad in later years and worked well on the Air Force F-111 Aardvark and Navy F-14 Tomcat. The B-1B Lancer bomber uses such a wing today.

But in every other respect, the XF10F-1 was a mess. The J40 engine was a malignancy that could not be cured. The double-delta “T” tail of the XF10F-1 was designed to be simpler by not requiring hydraulics. Instead, a small, pilot-controlled canard at the front of a large fairing on the tail was used to move the large mass of the stabilator itself, much like a trim tab on an aileron or elevator. Wind tunnel tests seemed to prove the tail would work. Real life flight tests showed the system was sluggish and unresponsive at best, and often caused pilot-induced oscillations. Constant modifications failed to make the tail satisfactory. The XF10F-1, wrote Francillon, suffered “overwhelming stability and control problems.” By the time an F9F-6 Cougar horizontal tail was fitted, curing most of the problems, the aircraft had been passed by.

In April 1953, the Navy cancelled the program. The second XF10F-1 test ship was only partially completed. Both XF10F-1s eventually went to Philadelphia, Penn., where they were intentionally destroyed in barrier testing.

“The XF10F-1 embodied so many new features that, in retrospect, it seems that the airplane was almost predestined not to succeed,” Meyer wrote in “Grumman Swing-Wing XF10F-1 Jaguar ” (Simi Valley, Calif.: Steve Ginter, 1993). Meyer also wrote that for its purpose the Jaguar was a “resounding success:” It vindicated the swing wing that later performed so successfully on the Tomcat.

When flying ended on April 25, 1953, the XF10F-1 had never reached an altitude higher than 31,500 feet nor exceeded Mach 0.86 in level flight or Mach 0.97 in a dive.


Robert F. Dorr is an author, U.S. Air Force veteran, and retired American diplomat who...