Pratt & Whitney J52

The Pratt & Whitney J52 (company designation JT8A) is an axial-flow dual-spool turbojet engine originally designed for the United States Navy,[2] in the 40 kN (9,000 lbf) class. It powered the A-6 Intruder and the AGM-28 Hound Dog cruise missile. As of 2021 the engine was still in use in models of the A-4 Skyhawk.

J52/JT8A
A J52 cut-out showing its two spools
Type Turbojet
National origin United States
Manufacturer Pratt & Whitney
First run 1955
Major applications Douglas A-4 Skyhawk
Grumman A-6 Intruder
Northrop Grumman EA-6B Prowler
Number built >5,000[1]
Developed from Pratt & Whitney J57
Developed into Pratt & Whitney JT8D
P&W J52-P-408 being worked on in the USS Kitty Hawk's jet shop

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.[3] 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".[4] 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.[5]

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
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.[6]

Variants
AGM-28 Hound Dog nuclear cruise missile, powered by the J52-P-3 jet engine.
One of eight Grumman YA2F-1 Intruder prototypes, showing the original tiltable tailpipes.
J52-P-3
Flown in: AGM-28 Hound Dog. This variant produced 7,500 lbf (33,000 N) of thrust. 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.[7]
J52-P-6
Flown in: A-6A. This variant produced 8,500 lbf (38,000 N) of thrust and included the 23-degree downward swiveling nozzle.
J52-P6A
Flown in: A-4E, TA-4J, EA-6B (the first few). This variant produced 8,500 lbf (38,000 N) of thrust.
J52-P-8A/B
Flown in: A-4F/G/H/K, TA-4E/F/G/H, A-6E, EA-6B. This variant produced 9,300 lbf (41,000 N) of thrust.
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, and produced 11,200 lbf (50,000 N) of thrust.[8] Still in operation with Argentina, Brazil, and Indonesia
J52-P-409
(PW1212) 12,000 lbf (53 kN) 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,[9] but was not purchased. The P-409 engine was also proposed for use in the EA-6B ADVCAP,[10] 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.[11][12]
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, designed in China, would have increased thrust to 16,000 lbf (71 kN).[13]
JT8A
Company designation for initial versions of the J52
JT8B-1
(J52-P-6 / P-6A)
JT8B-3
(J52-P-8A)

Applications

Specifications (J52-P-408)

Data from Flight [14]

General characteristics
  • Type: turbojet
  • Length: 118 in (300 cm)
  • Diameter: 38 in (96.5 cm)
  • Dry weight: 2,318 lb (1,052 kg)

Components
  • Compressor: axial flow, 5-stage LP, 7-stage HP
  • Turbine: single stage HP, single stage LP
  • Fuel type: JP-4

Performance

See also

Related development

Comparable engines

Related lists

References

Notes
  1. Pratt & Whitney J52 page Archived 2015-03-04 at the Wayback Machine. Accessed 28 May 2016.
  2. Gunston 1989, p.122.
  3. Gunston 2006, p.154
  4. Quotations from Flight, 1961
  5. Aero Engines 1961 (1961). Flight, July 20, 1961. pp 93-94.
  6. National Museum of the Air Force. North American AGM-28B Hound Dog. "Fact Sheets : North American AGM-28B Hound Dog : North American AGM-28B Hound Dog". Archived from the original on 2007-11-15. Retrieved 2007-10-29. Access date: 20 October 2007.
  7. Griswold, W.S., "Mightiest Bomber Fires 1,000 Mile Missile" (1958). Popular Science. Sept. 1958, p.90-91.
  8. A-4 Skyhawk technical information - skyhawk.org Archived 2014-08-14 at the Wayback Machine Retrieved: 29 July 2009
  9. Greeley, B.M. Jr., "Congressional Clash Threatens A-6F, A-6E Compromise Effort" (1988). Aviation Week & Space Technology, Jan. 11, 1988. p.18.
  10. Polmar, N. "EA-6B Prowler" (2001). The Naval Institute Guide to Ships and Aircraft of the U.S. Fleet, 17th Ed. 2001. p416-417.
  11. "P&W provides more EA-6 power" (1987). Flight International, Sept. 19, 1987. p.15.
  12. "Uprated A-4 Marketed" (1988). Flight International, Feb. 13, 1988. p.16.
  13. "Pratt & Whitney's PW1216 turbojet" (1987). Flight International. September 26, 1987. Page 62.
  14. Flightglobal archive - Flight International, 4 January 1973 Retrieved: 29 July 2009

Bibliography
  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
  • Jane's Information Group. Pratt & Whitney J52. Jane's Aero Engines. Modified 29 May 2009.
  • Gunston, Bill (2006). The Development of Jet and Turbine Aero Engines, 4th Edition. Sparkford, Somerset, England, UK: Patrick Stephens, Haynes Publishing. ISBN 0-7509-4477-3.
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