Background The origins of the Panther can be traced back to development studies performed by Grumman into jet-powered fighter aircraft near the end of
World War II. The company was keen to capitalise on the emergence of the first practical jet engines by integrating them into a new aircraft design. This design, which was internally designated
G-75, was submitted to a
United States Navy competition that sought a jet-powered
night fighter to equip its
aircraft carriers with. However, on 3 April 1946, it was announced that the
Douglas F3D Skyknight, a competing two-seat aircraft powered by four
Westinghouse J30 turbojets, had been selected. On 11 April 1946, the Navy's
Bureau of Aeronautics (BuAer) issued a development contract to Grumman to produce a pair of G-75 prototypes, which were given the Navy designation
XF9F-1, in case development of the Skyknight encountered severe problems. Shortly thereafter, Grumman recognised that the G-75 did not have much potential for either performance or growth; the company had already undertaken work on a completely different single-engine day fighter, the
G-79. In a bureaucratic maneuver, BuAer opted not to cancel the G-75 contract, but instead changed the wording to include three prototypes of the entirely different G-79. It was this design that became the Panther. At that time, the few American engines that were available for use, such as the
Allison J33 and
Westinghouse J34, were not considered to be sufficiently reliable; thus, the Navy specified the imported
Rolls-Royce Nene turbojet, which was also more powerful, at of thrust. Production aircraft were to also be powered by the Nene, built
under license by
Pratt & Whitney as the J42. Since there was insufficient space within the wings and fuselage to provide sufficient fuel for the thirsty jet engine, the design team opted to add permanently mounted
wingtip fuel tanks, which had the incidental advantage of improving the fighter's rate of
roll. The wings featured another innovation in the form of
leading edge flaps that generated additional lift while landing;
speed brakes were also present on the underside of the fuselage.
Flight testing On 21 November 1947, the prototype Panther conducted its
maiden flight, piloted by test pilot Corky Meyer. It was followed by the second prototype only five days later. Initial issues with directional and longitudinal stability were encountered, but were quickly rectified. During one early land-based
arresting gear test, the detachable rear section of the aircraft unintentionally came off; remedial changes were made to avoid any future repetition. During May 1949, carrier suitability trails commenced. In September 1949, the F9F was cleared for flight from aircraft carriers. During the development phase, Grumman decided to change the Panther's engine, selecting the
Pratt & Whitney J48-P-2, a license built version of the
Rolls-Royce RB.44 Tay. The other engine that had been tested was the Allison J33-A-16. The armament was a quartet of 20 mm guns, the Navy having already switched to this caliber (as opposed to the USAAF/USAF which continued to use .50 caliber
M2/M3 guns). In addition, the Panther was soon armed with underwing air-to-ground rockets and up to of bombs. From 1946, interest in developing an aircraft that harnessed the increasingly popular
swept wing grew and, following concerns that the Panther was inferior to its MiG opponents over the skies of Korea, Grumman launched work on a conversion project, known as Design 93. This effort resulted in a swept-wing derivative, the
F9F Cougar, which retained the Panther's designation number. Later stage development work on the Panther continued, being largely focused on engine improvements, expanding fuel capacity, and the use of alternative munitions. In 1949, the Panther was considered by the
Australian government, as a possible locally-built replacement for the
Mustang Mk 23 and
De Havilland Vampire then operated by the
Royal Australian Air Force (RAAF). The other designs considered initially were an Australian design, the
CAC CA-23 (an unconventional, twin-jet
all-weather fighter) and the
Hawker P.1081. By mid-1950, however, RAAF Mustangs were in action in
Korea and seen as highly vulnerable to the
MiG-15. An immediately available stop-gap in the shape of the
Gloster Meteor F.8 was operated by the RAAF in Korea from July 1951. (After its less-than-satisfactory performance against MiGs, the Meteor was replaced from 1954 by the
CAC Sabre – an Australian-built, up-engined variant of the F-86.) ==Operational history==