| JT9D | |
|---|---|
 The internal structure of the JT9D | |
| Type | Turbofan |
| National origin | United States |
| Manufacturer | Pratt & Whitney |
| First run | December 1966 |
| Major applications | |
| Number built | 3,200+[1] |
| Developed into | |
ThePratt & Whitney JT9D engine was the firsthigh bypass ratiojet engine to power awide-body airliner.[2] Its initial application was theBoeing 747-100, the original "Jumbo Jet". It wasPratt & Whitney's first high-bypass-ratio turbofan.[3]
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 theBoeing 747.It subsequently powered theBoeing 767,Airbus A300 andAirbus A310, andMcDonnell Douglas DC-10.The enhanced JT9D-7R4 was introduced in September 1982 and was approved for 180-minuteETOPS fortwinjets in June 1985. By 2020, the JT9D had flown more than 169 million hours.Production ceased in 1990,[2] to be replaced by the newPW4000.
The JT9D was developed from the STF200/JTF14 demonstrator engines.[4] The JTF14 engine had been proposed for theC-5 Galaxy program but the production contract was awarded to theGeneral 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 aBoeing B-52E which served as a JT9D flyingtestbed.[5]In 1968, its unit cost was $800,000,[6] $7.2 million today.
The JT9D introduced advanced technologies in structures, aerodynamics, and materials, which includedtitanium alloys andnickel alloys, to improve fuel efficiency and reliability compared to thePratt & Whitney JT3D earlier turbofan.[2]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 USAFBoeing E-4A airborne command posts were designatedF105.
In 1973,NAVSEA selected the JT9D-70 for use as a high efficiency gas turbine in the 30,000 hp to 50,000 hp class, installing its compressor into the pre-existingFT4 marine gas turbine to create the FT9. The engine had been recommended for provisional acceptance in June 1980, with full acceptance pending for ship-specific installation. The engine was selected by the Navy for use in Rohr Marine's 3,000 ton Surface Effect Ship, and one was to be installed aboard the vessel GTSAsiafreighter.[9][10]
All variants have the same number of compressor and turbine stages.[11][12]
| Comp. | Model | Certification | Takeoff, dry | Length | Width | Weight | LP rpm | HP rpm | T/W | Fan[a] | Application |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 15-stage[11] | 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[13] |
| 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) | 96.61 in 2.454 m | 8,470 lb (3.84 t) | 3650 | 5.25 | McDonnell Douglas DC-10[14] | ||||
| JT9D-7H | Jun 19, 1974 | 45,500 lbf (202 kN) | 95.60 in 2.428 m | 8,880 lb (4.03 t) | 5.12 | Boeing 747[13] | |||||
| 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-7FW | Aug 2, 1982 | 50,000 lbf (220 kN) | 5.63 | ||||||||
| JT9D-7J | Aug 31, 1976 | 48,650 lbf (216.4 kN) | 5.48 | ||||||||
| JT9D-20J | Dec 29, 1986 | 48,050 lbf (213.7 kN) | 96.61 in 2.454 m | 8,580 lb (3.89 t) | 5.6 | ||||||
| 16-stage[12] | 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[14] Airbus A300[15] |
| JT9D-70A | 51,140 lbf (227.5 kN) | 9,155 lb (4.153 t) | 5.59 | Boeing 747[13] | |||||||
| 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[16] | |||
| JT9D-7R4D1 | Apr 1, 1981 | 8,915 lb (4.044 t) | 3810 | 5.38 | Airbus A310[15] | ||||||
| JT9D-7R4E | 50,000 lbf (220 kN) | 3770 | 5.61 | Boeing 767[16] | |||||||
| JT9D-7R4E1 | 154.295 in 3.9191 m | 8,935 lb (4.053 t) | 3810 | 5.6 | Airbus A310[15] | ||||||
| JT9D-7R4G2 | Jul 23, 1982 | 54,750 lbf (243.5 kN) | 9,170 lb (4.16 t) | 3825 | 8080 | 5.97 | Boeing 747[13] | ||||
| JT9D-7R4H1 | 56,000 lbf (250 kN) | 8,915 lb (4.044 t) | 3810 | 6.28 | Airbus A300-600[15] | ||||||
| JT9D-7R4E4 | Mar 29, 1985 | 50,000 lbf (220 kN) | 8,935 lb (4.053 t) | 5.6 | Boeing 767[16] |
Data from Pratt & Whitney[2]
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