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Pratt & Whitney JT9D: Wikis


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The internal structure of the JT9D.
Type Turbofan
Manufacturer Pratt & Whitney
First run December 1966
Major applications Boeing 747
Airbus A310
McDonnell Douglas DC-10

The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body aircraft. Its initial application was the Boeing 747-100, the original "Jumbo Jet". It was the company's first high-bypass-ratio turbofan and also the first of today's generation of large commercial turbofan engines to be produced.[1]


Design and development

The JT9D was developed as part of the design phase of the C-5 Galaxy, a contract was awarded to Pratt & Whitney to study the type of large engine needed but the production contract was eventually awarded to General Electric and their TF39 turbofan. The JT9D was however chosen by Boeing to power the 747 with that aircraft's first flight taking place on 9 February 1969. Flight testing of the engine had begun in June 1968, using a Boeing B-52E as a testbed.

The JT9D-3 which entered service in 1970 was constructed using titanium and nickel alloys. 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. This version of the JT9D weighed 8,608 lb and produced 43,500 lbf thrust. Production ceased in 1990.

Pratt & Whitney's designated successor to the JT9D family is the PW4000, which features fewer parts, greater reliability, and lower base selling price.



JT9D Engine Family
JT9D-3A JT9D-7 JT9D-20 JT9D-7Q/7Q3 JT9D-59A/70A JT9D-7R4D/D1 JT9D-7R4H1
Static Thrust (lbf) 45800 47900 49400 53000 53000 48000 56000
Basic Engine Weight (lb) 8608 8850 8450 9295 9155 8905 8885
Length (in) 128.2 128.2 128.2 132.1 132.2 132.7 132.7
Fan Diameter (in) 92.3 92.3 92.3 93.6 93.6 93.4 93.4

See also

Related development

Comparable engines

Related lists




  1. ^ Gunston 1989, p.126.


  • Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9

External links


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