Research and development of the Grumman F9F Panther didn’t go as smoothly as the Navy or Northrop Grumman anticipated. The airplane manufacturer obtained the contract to develop a jet plane capable of taking off and landing on an airplane carrier in April of 1946, but it wouldn’t be until December 1949 that the first F9F Panther would take flight.
Initially, the contract awarded to Northrop Grumman was for the production of a fighter called the G-75, which was later designated the XF9F-1. The plane was a two-seat night fighter with wing-mounted turbojet engines. Four engines in total were required due to the comparatively weak power of jet engines in the mid-1940s, as engineers tested different configurations with the new technology.
Eventually, a shift in the project would lead Northrop Grumman to alter the program to develop a single-seat, single-jet day fighter. To do so, the company would equip the jets with Rolls-Royce Nene jet engines capable of generating 5,000 pounds of thrust. This new variation now held the designation of the XF9F-2 and would take its first flight on November 21, 1947.
Soon after, engineers would replace the Nene engine with an increased thrust version of the Alison J33 engine in the F9F-4 version of the plane, then finally with the Pratt & Whitney J48 variation of the Rolls-Royce Tay engine, which would become the F9F-5, the final designation for the Panther.
