Pratt & Whitney J57

The Pratt & Whitney J57, whose company designation is JT3C, is a two-spool axial-flow turbojet developed in the early 1950s. First run in January 1950, it was the first engine of the 10,000 pound-force (45 kN) thrust class in the United States. It grew out of the Pratt & Whitney XT45 turboprop intended for the Boeing XB-52, and where General Electric chose a variable-geometry compressor for its J79, Pratt & Whitney split the compressor into low-pressure and high-pressure units on separate shafts so the engine stayed stable at a high overall pressure ratio. Production ran from 1951 to 1965 and 21,170 were built. It powered fighters, bombers and jetliners including the Boeing B-52, the F-100 Super Sabre, the Lockheed U-2, the Boeing 707 and the Douglas DC-8, and it was developed into the J52, the J75, the JT3D and TF33 turbofans and a stationary gas turbine. Leonard S. Hobbs received the 1952 Collier Trophy for designing and producing it.