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Pratt & Whitney JT3D engine, American Airlines Museum, Dallas Fort Worth, Texas. | by RuthannOC
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Pratt & Whitney JT3D engine, American Airlines Museum, Dallas Fort Worth, Texas.

Pratt & Whitney JT3D - Best Viewed Large/Original Size


The Pratt & Whitney JT3D is an early turbofan engine derived from the

Pratt & Whitney JT3C turbojet and was first flown in 1958. Over 8,000

JT3Ds were produced between 1959 and 1985. Most JT3D engines still in

service today are used on military aircraft, where the engine is

referred to by its USAF designation of TF33.

In 1959 important orders for the engine were the Boeing 707-120B and

Boeing 720B when American Airlines ordered one 707 powered by JT3D

turbofans and KLM order JT3D powered Douglas DC-8. The earlier 707s

had been powered by the turbojet JT3C and the improved efficiency of

the turbofan soon attracted the airlines. A JT3D powered 707-123B and

720-023B (the suffix B was to indicate a turbofan powered aircraft)

entered service with American Airlines on the same day, March 12,

1961. The next development of the 707 (the -300 series) were only

offered with JT3D turbofans.[1]

The Boeing KC-135 Stratotankers were all originally powered by

turbojet engines, although some of the more specialised variants were

fitted with TF33s. With the demise of many airline 707s the United

States Air Force took the opportunity to buy the surplus airframes

and use the engines to re-engine the KC-135As used by the Air

National Guard and reserve squadrons with the civilian JTD3

(designated TF33-PW-102). Over 150 aircraft were modified and the

former KC-135A were re-designated the KC-135E.[1]

After long service for both airlines and air forces the number of

JT3D powered aircraft is steadily decreasing. 135 KC-135s use the

JT3D while 354 were fitted with CFM International CFM56 engines which

provide greater thrust and increased operational flexibility due to

their lower noise footprint. The noise of the JT3D is one of the

reasons NATO has debated re-engining their E-3 Sentry AWACS fleet,

with the aircraft subject to restrictions that modern-engined

aircraft are not. Operational flexibility would be further increased

due to the ability of higher power engines to increase the ceiling of

the aircraft, extending the horizon for radar surveillance, e.g RAF,

French and Saudi E-3s routinely fly higher than NATO/USAF

counterparts. However the main funding for such a programme would

come from the United States who most likely wish to upgrade their own

fleet first.[attribution needed]

Another well known aircraft which was fitted with the JT3D (in TF33

form) was the Boeing B-52H Stratofortress. The 'H' model of the B-52

was the only variant of the famous bomber to be fitted with turbofan

engines, and the only model remaining in US Air Force service. It is

expected to remain as a mainstay of the USAF heavy bomber fleet until

at least 2030.




18,000lb (80.1 kN) thrust civil version


17,000lb (75.6 kN) thrust for the B-52H


18,000lb (80.1 kN thrust for the KC-135


21,000lb (93.4 kN) thrust for the C-141


16,000lb (71.2 kN) thrust for the B-57

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Taken on September 11, 2007