The Pratt & Whitney JT9D engine was the first

high bypass The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for ev ...

ratio jet engine to power a

wide-body airliner A wide-body aircraft, also known as a twin-aisle aircraft, is an airliner with a fuselage wide enough to accommodate two passenger aisles with seven or more seats abreast. The typical fuselage diameter is . In the typical wide-body economy cabin ...

. Its initial application was the Boeing 747-100, the original "Jumbo Jet". It was Pratt & Whitney's first high-bypass-ratio turbofan.

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 The Airbus A300 is a wide-body airliner developed and manufactured by Airbus. In September 1967, aircraft manufacturers in the United Kingdom, France, and West Germany signed a memorandum of understanding to develop a large airliner. West ...

and

Airbus A310 The Airbus A310 is a wide-body aircraft, designed and manufactured by Airbus Industrie, then a consortium of European aerospace manufacturers. Airbus had identified a demand for an aircraft smaller than the A300, the first twin-jet wide-bod ...

, and

McDonnell Douglas DC-10 The McDonnell Douglas DC-10 is an American trijet wide-body aircraft manufactured by McDonnell Douglas. The DC-10 was intended to succeed the DC-8 for long- range flights. It first flew on August 29, 1970; it was introduced on August 5, 197 ...

. The enhanced JT9D-7R4 was introduced in September 1982 and was approved for 180-minute

ETOPS ETOPS () is an acronym for ''Extended-range Twin-engine Operations Performance Standards''—a special part of flight rules for one-engine-inoperative flight conditions. The International Civil Aviation Organization (ICAO) coined the acronym for ...

for

twinjet A twinjet or twin-engine jet is a jet aircraft powered by two engines. A twinjet is able to fly well enough to land with a single working engine, making it safer than a single-engine aircraft in the event of failure of an engine. Fuel efficien ...

s 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 Pratt & Whitney PW4000 is a family of dual-spool, axial-flow, high-bypass turbofan aircraft engines produced by Pratt & Whitney as the successor to the JT9D. It was first run in April 1984, was FAA certified in July 1986, and was introdu ...

. The JT9D was developed from the STF200/JTF14 demonstrator engines. The JTF14 engine had been proposed for the

C-5 Galaxy The Lockheed C-5 Galaxy is a large military transport aircraft designed and built by Lockheed, and now maintained and upgraded by its successor, Lockheed Martin. It provides the United States Air Force (USAF) with a heavy intercontinental-rang ...

program but the production contract was awarded to the

General Electric TF39 The General Electric TF39 was a high-bypass turbofan engine that was developed to power the Lockheed C-5 Galaxy. The TF39 was the first high-power, high-bypass jet engine developed. The TF39 was further developed into the CF6 series of engines, a ...

. 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-52 The Boeing B-52 Stratofortress is an American long-range, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Air ...

E which served as a JT9D flying

testbed A testbed (also spelled test bed) is a platform for conducting rigorous, transparent, and replicable testing of scientific theories, computational tools, and new technologies. The term is used across many disciplines to describe experimental rese ...

. In 1968, its unit cost was $800,000, $ million today.

Design

The JT9D introduced advanced technologies in structures, aerodynamics, and materials, which included

titanium alloy Titanium alloys are alloys that contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness (even at extreme temperatures). They are light in weight, have extraordinary corrosion resista ...

s and nickel alloys, to improve fuel efficiency and reliability compared to the

Pratt & Whitney JT3D The Pratt & Whitney JT3D is an early turbofan aircraft engine derived from the Pratt & Whitney JT3C. It was first run in 1958 and was first flown in 1959 under a B-45 Tornado test aircraft. Over 8,000 JT3Ds were produced between 1959 and 1985. M ...

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. 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-4 The Boeing E-4 Advanced Airborne Command Post (AACP), the current "Nightwatch" aircraft, is a strategic command and control military aircraft operated by the United States Air Force (USAF). The E-4 series are specially modified from the Boeing ...

A airborne command posts were designated F105.

Variants

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

Applications

* Boeing 747-100/200/300/ SP * Boeing 767 (early models) * Boeing RC-1 *

McDonnell Douglas DC-10-40 The McDonnell Douglas DC-10 is an American trijet wide-body aircraft manufactured by McDonnell Douglas. The DC-10 was intended to succeed the DC-8 for long-range flights. It first flew on August 29, 1970; it was introduced on August 5, 1971, ...

Specifications (JT9D-7R4)

References

External links

* {{DEFAULTSORT:Pratt and Whitney JT9D High-bypass turbofan engines

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. Dev ...

1960s turbofan engines