Pratt & Whitney JT9D

The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body airliner. Its initial application was the Boeing 747-100, the original "Jumbo Jet". It was Pratt & Whitney's first high-bypass-ratio turbofan.[2]

JT9D
The internal structure of the JT9D
Type Turbofan
National origin United States
Manufacturer Pratt & Whitney
First run December 1966
Major applications Airbus A300/A310
Boeing 747
Boeing 767
McDonnell Douglas DC-10
Number built more than 3,200[1]
Developed into Pratt & Whitney PW4000

Development
The Pratt & Whitney JT9D high-bypass turbofan engine was developed for the Boeing 747

The JT9D program was launched in September 1965 and the first engine was tested in December 1966. It received its FAA certification in May 1969 and entered service in January 1970 on the Boeing 747. It subsequently powered the Boeing 767, Airbus A300 and Airbus A310, and McDonnell Douglas DC-10. The enhanced JT9D-7R4 was introduced in September 1982 and was approved for 180-minute ETOPS for twinjets in June 1985. By 2020, the JT9D had flown more than 169 million hours. Production ceased in 1990,[3] to be replaced by the new PW4000.

The JT9D was developed from the STF200/JTF14 demonstrator engines.[4] The JTF14 engine had been proposed for the C-5 Galaxy program but the production contract was awarded to the General Electric TF39. The engine's first test run took place in a test rig at East Hartford, Connecticut, with the engine's first flight in June 1968 mounted on a Boeing B-52E which served as a JT9D flying testbed.[5] In 1968, its unit cost was $800,000,[6] $6.7 million today.

Design

The JT9D introduced advanced technologies in structures, aerodynamics, and materials, which included titanium alloys and nickel alloys, to improve fuel efficiency and reliability compared to the Pratt & Whitney JT3D earlier turbofan.[3] The engine featured a single-stage fan, a three-stage low-pressure compressor, and an eleven-stage high-pressure compressor coupled to a two-stage high-pressure turbine and four-stage low-pressure turbine. The JT9D-3, the earliest certified version of the engine, weighed 8,470 lb (3,840 kg) and produced 43,500 lbf (193 kN) thrust.[7]

Pratt & Whitney faced difficulties with the JT9D design during the Boeing 747 test program. Engine failures during the flight test program resulted in thirty aircraft being parked outside the factory with concrete blocks hanging from the pylons, awaiting redesigned engines. Boeing and Pratt & Whitney worked together in 1969 to solve the problem. The trouble was traced to ovalization, in which stresses during takeoff caused the engine casing to deform into an oval shape resulting in rubbing of high-pressure turbine blade tips. This was solved by strengthening the engine casing and adding yoke-shaped thrust links.[8]

JT9D engines powering USAF Boeing E-4A airborne command posts were designated F105.

Variants

All variants have the same number of compressor and turbine stages.[9][10]

Comp. Model Certification Takeoff, dry Length Width Weight LP rpm HP rpm T/W Fan[lower-alpha 1] Application
15-stage[9] JT9D-3A Jan 9, 1970 43,500 lbf (193 kN) 154.89 in
3.934 m		 95.60 in
2.428 m		 8,713 lb (3.952 t) 3650 7850 4.99 92.3 in
2.34 m		 Boeing 747[11]
JT9D-7 Jun 14, 1971 45,500 lbf (202 kN) 8,880 lb (4.03 t) 3750 8000 5.12
JT9D-7A Sep 22, 1972 46,150 lbf (205.3 kN) 5.2
JT9D-20 Oct 16, 1972 44,500 lbf (198 kN) 8,470 lb (3.84 t) 3650 5.25 McDonnell Douglas DC-10[12]
JT9D-7H Jun 19, 1974 45,500 lbf (202 kN) 8,880 lb (4.03 t) 5.12 Boeing 747[11]
JT9D-7AH 46,150 lbf (205.3 kN) 5.2
JT9D-7F Sep 30, 1974 46,750 lbf (208.0 kN) 3750 5.26
JT9D-7J Aug 31, 1976 48,650 lbf (216.4 kN) 5.48
JT9D-20J Dec 29, 1986 48,050 lbf (213.7 kN) 8,580 lb (3.89 t) 5.6 McDonnell Douglas DC-10[12]
16-stage[10] JT9D-59A Dec 12, 1974 51,720 lbf (230.1 kN) 154.256 in
3.9181 m		 97.03 in
2.465 m		 9,140 lb (4.15 t) 3780 8011 5.66 93.6 in
2.38 m		 McDonnell Douglas DC-10[12]
Airbus A300[13]
JT9D-70A 51,140 lbf (227.5 kN) 9,155 lb (4.153 t) 5.59 Boeing 747[11]
JT9D-7Q Oct 31, 1978 51,900 lbf (231 kN) 9,295 lb (4.216 t) 3888 8000 5.58
JT9D-7Q3 Oct 22, 1979 3960 5.58
JT9D-7R4D Nov 25, 1980 48,000 lbf (210 kN) 96.00 in
2.438 m		 8,935 lb (4.053 t) 3770 5.37 93.4 in
2.37 m		 Boeing 767[14]
JT9D-7R4D1 Apr 1, 1981 8,915 lb (4.044 t) 3810 5.38 Airbus A310[13]
JT9D-7R4E 50,000 lbf (220 kN) 3770 5.61 Boeing 767[14]
JT9D-7R4E1 154.295 in
3.9191 m		 8,935 lb (4.053 t) 3810 5.6 Airbus A310[13]
JT9D-7R4G2 Jul 23, 1982 54,750 lbf (243.5 kN) 9,170 lb (4.16 t) 3825 8080 5.97 Boeing 747[11]
JT9D-7R4H1 56,000 lbf (250 kN) 8,915 lb (4.044 t) 3810 6.28 Airbus A300-600[13]
JT9D-7R4E4 Mar 29, 1985 50,000 lbf (220 kN) 8,935 lb (4.053 t) 5.6 Boeing 767[14]

Applications

Specifications (JT9D-7R4)

Data from Pratt & Whitney[3]

General characteristics
  • Type: High bypass turbofan
  • Length: 132.7 in (3.37 m) (flange to flange)
  • Diameter: 93.4 in (2.37 m) (fan tip)
  • Dry weight: 8,608 lb (3,905 kg)

Components
  • Compressor: 3-stage low pressure 11-stage high pressure axial
  • Turbine: 2-stage high pressure 4-stage low pressure

Performance

See also

Related development

Comparable engines

Related lists

References
  1. "Commercial Engines / JT9D". Pratt & Whitney.
  2. Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9, p.126.
  3. "JT9D" (PDF). Pratt & Whitney.
  4. The Engines of Pratt & Whitney: A Technical History, Jack Connors, ISBN 978 1 60086 711 8, p.409
  5. The Engines of Pratt & Whitney: A Technical History, Jack Connors, ISBN 978 1 60086 711 8, p.412
  6. Aero Engines 1968 Flight International 4 January 1968
  7. The Engines of Pratt & Whitney A Technical History, Jack Connors, ISBN 978 1 60086 711 8, Table 3
  8. Flight International, 13 November 1969, p.749
  9. "Type Certificate data sheet Number E20EA" (PDF). FAA. February 10, 2000.
  10. "Type Certificate data sheet Number E3NE" (PDF). FAA. July 25, 2019.
  11. "Type Certificate Data Sheet NO. A20WE" (PDF). FAA. February 27, 2015.
  12. "Type Certificate Data Sheet A22WE" (PDF). FAA. April 30, 2018.
  13. "Type certificate data sheet A.172 for Airbus A300, A310 and A300-600" (PDF). EASA. 11 March 2019. Archived from the original (PDF) on 16 March 2019. Retrieved 26 March 2020.
  14. "Type Certificate Data Sheet No. A1NM" (PDF). June 20, 2016. Archived from the original (PDF) on September 29, 2018. Retrieved March 26, 2020.
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