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 first "jumbo jet". It was Pratt & Whitney's first high-bypass-ratio turbofan.Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. , p. 126.

Development

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, to be replaced by the new PW4000.

The JT9D was developed from the STF200/JTF14 demonstrator engines.The Engines of Pratt & Whitney: A Technical History, Jack Connors, , p.409 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.The Engines of Pratt & Whitney: A Technical History, Jack Connors, , p.412 In 1968, its unit cost was $800,000,Aero Engines 1968 Flight International 4 January 1968 $ 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. 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 and produced thrust.The Engines of Pratt & Whitney A Technical History, Jack Connors, , Table 3

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.Flight International, 13 November 1969, p.749

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

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-existing FT4 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 GTS Asiafreighter.Groghan, D. A., Miller, C. L (1981). Development of FT9 Marine Gas Turbine (PDF). Paper Number 81-GT-197. The American Society of Mechanical Engineers.

Variants All variants have the same number of compressor and turbine stages.

+ Model Certification Takeoff, dry Length Width Weight rpm rpm Fan Application 15-stage JT9D-3A Jan 9, 1970 3650 7850 Boeing 747 JT9D-7 Jun 14, 1971 3750 8000 JT9D-7A Sep 22, 1972 JT9D-20 Oct 16, 1972 3650 McDonnell Douglas DC-10 JT9D-7H Jun 19, 1974 Boeing 747 JT9D-7AH JT9D-7F Sep 30, 1974 3750 JT9D-7FW Aug 2, 1982 JT9D-7J Aug 31, 1976 JT9D-20J Dec 29, 1986 16-stage JT9D-59A Dec 12, 1974 3780 8011 McDonnell Douglas DC-10Airbus A300 JT9D-70A Boeing 747 JT9D-7Q Oct 31, 1978 3888 8000 JT9D-7Q3 Oct 22, 1979 3960 JT9D-7R4D Nov 25, 1980 3770 Boeing 767 JT9D-7R4D1 Apr 1, 1981 3810 Airbus A310 JT9D-7R4E 3770 Boeing 767 JT9D-7R4E1 3810 Airbus A310 JT9D-7R4G2 Jul 23, 1982 3825 8080 Boeing 747 JT9D-7R4H1 3810 Airbus A300-600 JT9D-7R4E4 Mar 29, 1985 Boeing 767

Applications Airbus A300 Airbus A310 Boeing 747-100/-100SR/-100B/-200B/-300/SP Boeing 767 (early models) Boeing RC-1 McDonnell Douglas DC-10-40

Specifications (JT9D-7R4)

See also

References

External links