Pratt & Whitney JT8D

The Pratt & Whitney JT8D is a low-bypass (0.96 to 1) turbofan engine, introduced by Pratt & Whitney in February 1963 with the inaugural flight of Boeing's 727. It was a modification of the Pratt & Whitney J52 turbojet engine, which powered the US Navy A-6 Intruder attack aircraft. The Volvo RM8 is an afterburning version that was license-built in Sweden for the Saab 37 Viggen fighter. Pratt & Whitney also sells static versions for powerplant and ship propulsion as the FT8.

Design

The JT8D is an axial-flow front turbofan engine incorporating dual-spool design. There are two coaxially-mounted independent rotating assemblies: one rotating assembly for the low pressure compressor (LPC) which consists of the first six stages (i.e. six pairs of rotating and stator blades, including the first two stages which are for the bypass turbofan), driven by the second (downstream) turbine (which consists of three stages); and a second rotating assembly for the high-pressure compressor (HPC) section, which has seven stages. The high-pressure compressor is driven by the first (upstream) turbine, which has a single stage.