Pratt & Whitney JT3D

The Pratt & Whitney JT3D ( military designation Pratt & Whitney TF33 ) is a two-shaft turbofan engine of the U.S. engine manufacturer Pratt & Whitney.

It is essentially based on the Pratt & Whitney JT3, but the compressor was changed so that the first three stages of the compressor were replaced by two new stages, which were designed as a fan. This produced a fan bypass flow around the core engine. The pass ratio was about 1.37. The compression ratio was 13,6:1. To drive the larger fan, an additional turbine was installed. The compressor has a total of 2 fan and 13 compressor stages, the turbine has a total of 4 levels. The air flow rate is a maximum of 204 kg / s

It has been one of the first engines of this kind after the Rolls- Royce Conway. With the fan, the thrust of about 55 kN in the main engine increased to about 80 kN. The prototype of the engine first flew in 1958. By 1985, about 8600 engines were produced in total.

This engine was known for use in the Boeing 707, the Douglas DC-8, B- 52H and different variants of the C -135 / KC - 135th Less well known was the use of the Lockheed C- 141st In the 90 B- 52H of the U.S. Air Force and a few Chilean KC- 135E is still in use today. In commercial air transport the mid-1970s it has been largely replaced due to the stricter noise regulations by more modern types.