Pratt & Whitney J52


The Pratt & Whitney J52 is an axial-flow dual-spool turbojet engine originally designed for the United States Navy, in the 40 kN class. It powered the A-6 Intruder and the AGM-28 Hound Dog cruise missile. the engine was still in use in models of the A-4 Skyhawk and the EA-6B Prowler.
The engine is the basis for the Pratt & Whitney JT8D, a popular civilian low-bypass turbofan engine.

Design and development

The J52 was developed in the mid-1950s for the US Navy as a scaled-down derivative of the J57/JT3A. It was initially intended to power the A4D-3 Skyhawk, an advanced avionics model that was canceled in 1957. After being canceled, the U.S. Air Force selected the J52 to power the AGM-28 Hound Dog cruise missile. The engine was designed with several unique features for this application, including a "conical centerbody mounted in the intake" and a "variable central plug... in the nozzle". Then, in 1958, the US Navy selected the engine to power what became the A-6 Intruder.
The J52-P-6 model, designed for the YA2F-1 Intruder, had a unique nozzle that could be angled downward at 23 degrees for STOL takeoffs; this was not used on production A-6s. Returning full circle, the J52 was selected to power the A4D-5, another model of the A-4 Skyhawk, remaining in all subsequent new-built models.
The twin-spool J52 employs a split 12-stage axial compressor consisting of a five-stage low pressure unit and a seven-stage high pressure unit. Behind the compressor is a nine-unit can-annular combustion chamber and a two-stage split turbine.

Operational history

In 1960, U.S. Air Force's Strategic Air Command developed procedures so that the Boeing B-52 Stratofortress could use the Hound Dog's J52 engine for additional thrust while the missile was located on the bomber's two pylons. This helped heavily laden B-52s fly away from their airbases faster, which would have been useful in case of nuclear attacks on the bases. The Hound Dog could then be refueled from the B-52's wing fuel tanks.

Variants

;J52-P-3
;J52-P-6
;J52-P6A
;J52-P-8A/B
;J52-P-408
;J52-P-409
;PW1212:J52-P-409 re-designated
;PW1216
;JT8A:Company designation for initial versions of the J52
;JT8B-1:
;JT8B-3:

Applications