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thumb|P&W J52-P-408 being worked on in the [[USS Kitty Hawk (CV-63)|USS Kitty Hawks jet shop]]

The Pratt & Whitney J52 (company designation JT8A) is an axial-flow dual-spool turbojet engine originally designed for the United States Navy, in the 40&nbsp;kN (9,000 lbf) 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.

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 (YA-6A) 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

thumb|right|B-52F takeoff with J52-powered AGM-28 Hound Dog missiles

In 1960, U.S. Air Force's Strategic Air Command (SAC) 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

thumb|right|AGM-28 Hound Dog nuclear cruise missile, powered by the J52-P-3 jet engine.

thumb|right|One of eight Grumman YA2F-1 Intruder prototypes, showing the original tiltable tailpipes.

Thrust given in foot-pounds (lbf) and kilonewtons (kN).

;J52-P-3

: Flown in: AGM-28 Hound Dog. The design of the P-3 model included a variable inlet duct to improve engine efficiency at the various altitudes the cruise missile was designed to fly at.

;J52-P-6

: Flown in: A-6A. Included a 23-degree downward swiveling nozzle

;J52-P6A

: Flown in: A-4E, TA-4J, EA-6B (the first few)

;J52-P-8A/B

: Flown in: A-4F/G/H/K, TA-4E/F/G/H, A-6E, EA-6B

;J52-P-408

: Flown in: A-4M/N, TA-4KU, EA-6B. This variant included variable inlet guide vanes (VIGV) in the LPC, air-cooled turbine blades Still in operation with Argentina, Brazil, and Indonesia

;J52-P-409

:(PW1212) thrust version of the J52-P-408 with an improved low pressure turbine (LPT) and faster acceleration. Designed for the EA-6B and was additionally marketed as an upgrade for the A-4. The J52-P-409 was also proposed as a cost-effective upgrade to the A-6E as an alternative to the A-6F Intruder II, but was not purchased. The P-409 engine was also proposed for use in the EA-6B ADVCAP, but that program was canceled after three prototypes were built and flown. The P-409 would have been available as a new engine or as an upgrade kit for P-408 engines, but was never ordered in significant quantities.

;PW1212:J52-P-409 re-designated

;PW1216

: An afterburning derivative of the J52-P409 engine proposed for the Grumman Sabre II concept (the project later evolved into the JF-17 Thunder). The afterburner was designed in China

;JT8A:Company designation for initial versions of the J52

;JT8B-1:(J52-P-6 / P-6A)

;JT8B-3:(J52-P-8A)

Applications

  • AGM-28 Hound Dog
  • Dassault Super Mystère
  • Douglas A-4 Skyhawk
  • Grumman A-6 Intruder
  • Lockheed Martin A-4AR Fightinghawk
  • Northrop Grumman EA-6B Prowler
  • LIMRV - On 14 August 1974, the LIMRV achieved a world record speed of 255.7&nbsp;mph (411.5&nbsp;km/h)

Specifications (J52-P-408)

See also

References

Notes

Bibliography

  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989.
  • Jane's Information Group. Pratt & Whitney J52. Jane's Aero Engines. Modified 29 May 2009.
  • Pratt & Whitney - J52