Pratt & Whitney JT4

The Pratt & Whitney JT4 was an axial-flow turbojet engine of the late 1950s. A two-spool design in the 17,000 lbf (76 kN) thrust class, JT4 was essentially the bigger brother of the Pratt & Whitney JT3C. It was known in military service as the J75, and in a variety of stationary roles as the FT4 or GG4.

Before the arrival of the Pratt & Whitney JT3D turbofan engine, the JT4A was used to power certain Boeing 707s and Douglas DC-8s models. It was used to improve field performance in the medium-range Boeing 707-220 and Douglas DC-8-20, and to achieve intercontinental range in the original Boeing 707-320 and the Douglas DC-8-30. In military use the JT4A engine had the designation J75, which was used on the Lockheed U-2, the Republic Aviation F-105 Thunderchief, and the Convair F-106 Delta Dart. It was also utilized in the prototype and experimental Lockheed A-12, North American YF-107, Vought XF8U-3 Crusader III, P6M SeaMaster, and CF-105 Arrow.

After its relatively short lifetime in the aircraft role, the JT4 found more enduring use in the naval role, where the FT4 was produced in a variety of models between 18,000 and 22,000 hp. Well-known uses include the first all-turbine warships, the Canadian Iroquois class destroyers, as well as the Coast Guard's Hamilton class cutters, and it was considered for the US Navy's Asheville class gunboat. The same basic powerplant saw much wider use as a peak demand power turbine running on natural gas. From its introduction in 1960 over 1,000 FT4s have been sold, with many of them still in operation for electrical generation. Outdated by modern standards, refits are available that add catalytic converters to lower their emissions.

References

* [http://www.pratt-whitney.com/vgn-ext-templating/v/index.jsp?vgnextoid=2e35288d1c83c010VgnVCM1000000881000aRCRD&prid=bb1c8f2e2ae3c010VgnVCM1000000881000a____ Pratt & Whitney Power Systems FT4/GG4]