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[update] 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 |
The engine is the basis for the Pratt & Whitney JT8D, a popular civilian low-bypass turbofan engine.
Design and development
editThe 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
editIn 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
edit- 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
edit- 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 mph (411.5 km/h)
Specifications (J52-P-408)
editData 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
- Maximum thrust: 11,200 lbf (50 kN)
- Overall pressure ratio: 14.6 : 1
- Air mass flow: 143 lb/s
- Specific fuel consumption: 0.79 lb/(lbf⋅h) (22 g/(kN⋅s))
- Thrust-to-weight ratio: 4.83
See also
editRelated development
Comparable engines
Related lists
References
editNotes
edit- ^ Pratt & Whitney J52 page Archived 2015-03-04 at the Wayback Machine. Accessed 28 May 2016.
- ^ Gunston 1989, p.122.
- ^ Gunston 2006, p.154
- ^ Quotations from Flight, 1961
- ^ Aero Engines 1961 (1961). Flight, July 20, 1961. pp 93-94.
- ^ 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.
- ^ Griswold, W.S., "Mightiest Bomber Fires 1,000 Mile Missile" (1958). Popular Science. Sept. 1958, p.90-91.
- ^ A-4 Skyhawk technical information - skyhawk.org Archived 2014-08-14 at the Wayback Machine Retrieved: 29 July 2009
- ^ Greeley, B.M. Jr., "Congressional Clash Threatens A-6F, A-6E Compromise Effort" (1988). Aviation Week & Space Technology, Jan. 11, 1988. p.18.
- ^ Polmar, N. "EA-6B Prowler" (2001). The Naval Institute Guide to Ships and Aircraft of the U.S. Fleet, 17th Ed. 2001. p416-417.
- ^ "P&W provides more EA-6 power" (1987). Flight International, Sept. 19, 1987. p.15.
- ^ "Uprated A-4 Marketed" (1988). Flight International, Feb. 13, 1988. p.16.
- ^ "Pratt & Whitney's PW1216 turbojet" (1987). Flight International. September 26, 1987. Page 62.
- ^ Flightglobal archive - Flight International, 4 January 1973 Retrieved: 29 July 2009
Bibliography
edit- 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.