In late 1953, General Electric began a design study of a high thrust-to-weight ratio turbojet engine. The prototype J85 engine ran in January 1956, the first flight was in August 1958 as the power plant of the McDonnell GAM-72 missile, and in September 1958 the prototype North American T-39 Sabreliner flew for the first time powered by the first man-rated J85 engines.
The J85 was the first U.S. small turbine engine to go into production with an afterburner. The most important applications were the Northrop T-38 Talon, the first supersonic trainer, and Northrop F-5 Freedom Fighter, a low-cost fighter used by many nations from the 1960s through the 1980s. The non-afterburning J85-GE-17A powered the Cessna A-37A/B attack aircraft. The J85 had the highest thrust-to-weight ratio of production engines built for its time (up to 7.3:1 on the J85-GE-21). GE built more than 12,000 J85 engines before production ended in 1988.