The Pratt & Whitney JT3D is an early

turbofan A turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a combination of references to the preceding generation engine technology of the turbojet and the add ...

aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either piston engines or gas turbin ...

derived from the Pratt & Whitney JT3C turbojet. It was first run in 1958 and was first flown in 1959 under a

B-45 Tornado The North American B-45 Tornado is an early American jet propulsion, jet bomber designed and manufactured by aircraft company North American Aviation. It has the distinction of being the first operational jet bomber to enter service with the Un ...

test aircraft. 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 US military designation of TF33.

Design and development

Aware of the competition from the

Rolls-Royce Conway The Rolls-Royce RB.80 Conway was the first turbofan jet engine to enter service. Development started at Rolls-Royce Limited, Rolls-Royce in the 1940s, but the design was used only briefly, in the late 1950s and early 1960s, before other turbof ...

turbofan, Pratt & Whitney decided to develop the JT3D turbofan from the JT3C

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

for later deliveries of the Boeing 707 and the Douglas DC-8, then nearing entry into service. A 2-stage fan replaced the first 3 stages of the 9-stage JT3C LP compressor. On the LP turbine, the second stage was enlarged and a third stage added. Unlike GE with the CJ805-23, Pratt & Whitney had not undertaken any transonic fan research prior to designing the JT3D, so they were unable to incorporate a single stage unit into the specification. Instead P&W designed a 2-stage unit based on some research they had done to support the J91 nuclear turbojet. On the Boeing 707 the JT3D fan nacelle was relatively short, whereas the Douglas DC-8 installation had a full-length fan cowl. Pratt & Whitney provided a kit whereby JT3Cs could be converted to the JT3D specification, and performance, during an overhaul. In 1959, important orders for the engine were the Boeing 707-120B and Boeing 720B when

American Airlines American Airlines, Inc. is a major airlines of the United States, major airline in the United States headquartered in Fort Worth, Texas, within the Dallas–Fort Worth metroplex, and is the Largest airlines in the world, largest airline in the ...

ordered one 707 powered by JT3D turbofans and KLM ordered a JT3D-powered

Douglas DC-8 The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is an early long-range Narrow-body aircraft, narrow-body jetliner designed and produced by the American Douglas Aircraft Company. Work began in 1952 towards the United States Air Force's (USA ...

. Earlier 707s and DC-8s had been powered by the JT3C and JT4A turbojets, 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

Boeing KC-135 Stratotanker The Boeing KC-135 Stratotanker is an American military aerial refueling tanker aircraft that was developed from the Boeing 367-80 prototype, alongside the Boeing 707 airliner. It has a narrower fuselage and is shorter than the 707. Boeing gave ...

s were all originally powered by turbojet engines. With the demise of many airline 707s, the

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

took the opportunity to buy the surplus airframes and use the engines to re-fit the KC-135As used by the Air National Guard and reserve squadrons with the civilian JT3D (designated TF33-PW-102). Over 150 aircraft were modified and the former KC-135A was re-designated the KC-135E.Tony Pither, The Boeing 707 720 and C-135, Air-Britain (Historians), 1998, TF33 engine at Davis-Monthan AFB 1984

After long service for both airlines and air forces, the number of JT3D-powered aircraft is steadily decreasing. One hundred thirty five KC-135s use the JT3D, while 354 were fitted with

CFM International CFM56 The CFM International CFM56 (U.S. military designation F108) series is a Franco-American family of high-bypass turbofan aircraft engines made by CFM International (CFMI), with a thrust range of . CFMI is a 50–50 joint-owned company of Safran ...

engines, which provide greater thrust, lower fuel consumption, and increased operational flexibility due to their lower noise footprint. The noise of the JT3D is one of the reasons

NATO The North Atlantic Treaty Organization (NATO ; , OTAN), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental Transnationalism, transnational military alliance of 32 Member states of NATO, member s ...

has debated re-fitting their E-3 Sentry AWACS fleet, since the aircraft are subject to restrictions that aircraft with modern engines 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; for instance, RAF, French and Saudi E-3s routinely fly higher than NATO/USAF counterparts. In 1961, the TF33-powered Boeing B-52H Stratofortress entered service. The "H" model of the B-52 was the only production variant of the heavy bomber to be fitted with turbofan engines, and is the only model remaining in United States Air Force service. It is expected to remain as a mainstay of the Air Force

heavy bomber Heavy bombers are bomber Fixed-wing aircraft, aircraft capable of delivering the largest payload of air-to-ground weaponry (usually Aerial bomb, bombs) and longest range (aeronautics), range (takeoff to landing) of their era. Archetypal heavy ...

fleet until at least 2040, with options for replacing the 8 TF33 engines with more modern equivalents being considered. In April 2020, the USAF released a request for proposals for 608 commercial replacement engines, with the plan to award the contract in May 2021. In September 2021, the USAF announced that the TF33 would be replaced by the Rolls-Royce F130.

Variants

TF-33-P-7 engine of C-141B at NAS Sigonella 2001

;JT3D-1 : thrust civil version, (Water injection optional) ;JT3D-2 : (TF33-P-3) ;JT3D-3: , (Water injection optional) ;JT3D-3A: (TF33-P-5) ;JT3D-3B: thrust civil version ;JT3D-5A: (TF33-P-7) , (Water injection optional) ;JT3D-8A: (TF33-P-7) , (Water injection optional) ;JT3D-7: thrust civil version ;JT3D-15: thrust civil version for the unbuilt 707-820 ;TF33-P-3 : thrust for the Boeing B-52H Stratofortress ;TF33-P-5 : thrust for the

;TF33-P-7 : thrust for the Lockheed C-141 Starlifter ;TF33-P-9 : thrust for the Boeing EC-135C and Boeing RC-135C ;TF33-P-11 : thrust for the Martin RB-57F Canberra ;TF33-PW-100A : thrust for the Boeing E-3 Sentry TF33-PW-102/A TF33-PW-103

Applications

;Civilian (JT3D) *

Boeing 707 The Boeing 707 is an early American long-range Narrow-body aircraft, narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes. Developed from the Boeing 367-80 prototype, the initial first flew on Decembe ...

* Boeing 720 *

* Shanghai Y-10 ;Military (TF33) * Boeing B-52H Stratofortress * Boeing C-18 * Boeing C-135 series ** EC-135 ** KC-135D/E Stratotanker (re-engined from retired donor airliners) ** OC-135B Open Skies ** RC-135 ** WC-135 * Boeing CC-137 * Boeing E-3 Sentry * Boeing VC-137B/C Stratoliner *

Northrop Grumman E-8 Joint STARS The Northrop Grumman E-8 Joint Surveillance Target Attack Radar System (Joint STARS) is a retired United States Air Force (USAF) airborne ground surveillance, battle management and command and control aircraft. It tracked ground vehicles and ...

* Lockheed C-141 Starlifter * Martin/General Dynamics RB-57F Canberra

Specifications (JT3D-8A / TF33-P-7)

References

Bibliography

External links

* {{DEFAULTSORT:Pratt and Whitney JT3D Low-bypass turbofan engines JT3D 1950s turbofan engines