Early flight tests of the first General Electric turbojet engine, the Type I-A, clearly showed the need for more power. GE followed with designs generating increased thrust, including the I-16, designated J31 by the military, which first ran in April 1943. About 250 were built, mainly for variants of the Bell P-59 Airacomet. This cutaway is representative of the engines installed in the production models of the Bell P-59A fighter aircraft.
When the government believed that future tactical needs would require turbojet engines to use the same fuel as reciprocating engines, GE further developed the engine for the U.S. Navy as a 100-octane, gasoline-burning version of the standard J31 engine, which normally ran on kerosene fuel. That version, along with a Wright R-1820 piston engine, powered the Ryan FR-1 Fireball, the Navy's first partially jet-powered aircraft.