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 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.

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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