The F9F-3 was developed in parallel with the F9F-2. It differed from the F9F-2 in being powered by the Allison J33 turbojet, which was approximately the same size as the J42 but was somewhat less powerful. The J33 had been planned as a second-source powerplant for the Panther in case the program to produce the Nene under license in the USA as the J42 proved unsuccessful. The first flight of the XF9F-3 (BuNo 122476) took place on August 16, 1948. It was powered by a 4600 lb.s.t. Allison J33-A-8 jet engine.
54 J33-powered F9F-3s were delivered to the Navy by Grumman between August 1948 and November 1949. They came off the production line in parallel with the J-42-powered F9F-2. Because of initially slow deliveries of J42 engines for the F9F-2, the F9F-3 was actually the first Panther version to enter service with the Navy, when F9F-3s replaced the FJ-1 Furies of VF-51 in May of 1949.
However, the J33 turned out in service to perform less well than the J42. In October 1949 virtually all F9F-3s were re-engined with 5750 lb.s.t. Pratt & Whitney J42 turbojets, and thereby became indistinguishable from the F9F-2. No further F9F-3s would be built, and further Navy contracts would be for the F9F-2 version.
In the summer of 1950, a re-engined F9F-3 (BuNo 122562) was fitted with an experimental electro-hydraulically driven Emerson Aero X17A roll-traverse turret housing four 0.50-inch machine guns. The guns could be directed at any angle from directly forward to 20 degrees aft, and the gun mount could be rolled the full 360 degrees in either direction. The turret could roll at a rate of 100 degrees per second, and the guns could be traversed at up to 200 degrees per second. Although the tests with the turret went fairly well, delays in the development of the associated radar and fire control system led to the project being cancelled in early 1954.
122476 Grumman XF9F-3 Panther 122560/122562 Grumman F9F-3 Panther 122564/122566 Grumman F9F-3 Panther 122568 Grumman F9F-3 Panther 122571 Grumman F9F-3 Panther 122573/122585 Grumman F9F-3 Panther 123020/123043 Grumman F9F-3 Panther 123068/123076 Grumman F9F-3 Panther