The Pratt & Whitney JT3D is an early

turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which achieves mechanic ...

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. 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 engine to enter service. Development started at Rolls-Royce in the 1940s, but the design was used only briefly, in the late 1950s and early 1960s, before other turbofan designs replaced it. ...

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, an ...

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 The Boeing 720 is an American narrow-body airliner produced by Boeing Commercial Airplanes. Announced in July 1957 as a 707 derivative for shorter flights from shorter runways, the 720 first flew on November 23, 1959. Its type certificate was i ...

when

American Airlines American Airlines is a major airlines of the United States, major US-based airline headquartered in Fort Worth, Texas, within the Dallas–Fort Worth metroplex. It is the Largest airlines in the world, largest airline in the world when measured ...

ordered one 707 powered by JT3D turbofans and

KLM KLM Royal Dutch Airlines, legally ''Koninklijke Luchtvaart Maatschappij N.V.'' (literal translation: Royal Aviation Company Plc.), is the flag carrier airline of the Netherlands. KLM is headquartered in Amstelveen, with its hub at nearby Amste ...

ordered a JT3D-powered

Douglas DC-8 The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is a long-range narrow-body airliner built by the American Douglas Aircraft Company. After losing the May 1954 US Air Force tanker competition to the Boeing KC-135, Douglas announced in July ...

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

JT4A The Pratt & Whitney J75 (civilian designation: JT4A) is an axial-flow turbojet engine first flown in 1955. A two-spool design in the 17,000 lbf (76 kN) thrust class, the J75 was essentially the bigger brother of the Pratt & Whitney J57 ...

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 Stratotankers 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 Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

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 Saf ...

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, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...

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 The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...

, 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 aircraft capable of delivering the largest payload of air-to-ground weaponry (usually bombs) and longest range (takeoff to landing) of their era. Archetypal heavy bombers have therefore usually been among the larges ...

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 Boeing KC-135 Stratotanker ;TF33-P-7 : thrust for the

Lockheed C-141 Starlifter The Lockheed C-141 Starlifter is a retired military strategic airlifter that served with the Military Air Transport Service (MATS), its successor organization the Military Airlift Command (MAC), and finally the Air Mobility Command (AMC) of the ...

;TF33-P-9 : thrust for the Boeing EC-135C and Boeing RC-135C ;TF33-P-11 : thrust for the

Martin RB-57F Canberra The Martin/General Dynamics RB-57F Canberra is a specialized strategic reconnaissance aircraft developed in the 1960s for the United States Air Force by General Dynamics from the Martin B-57 Canberra tactical bomber, which itself was a license- ...

;TF33-PW-100A : thrust for the Boeing E-3 Sentry TF33-PW-102/A TF33-PW-103

Applications

;Civilian (JT3D) * Boeing 707 *

Boeing 720 The Boeing 720 is an American narrow-body airliner produced by Boeing Commercial Airplanes. Announced in July 1957 as a 707 derivative for shorter flights from shorter runways, the 720 first flew on November 23, 1959. Its type certificate was ...

* 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 The OC-135B Open Skies is a United States Air Force observation aircraft that supports the Treaty on Open Skies. The aircraft, a modified WC-135B, flies unarmed observation flights over participating parties of the treaty. Three OC-135B aircr ...

RC-135 The Boeing RC-135 is a family of large reconnaissance aircraft built by Boeing and modified by a number of companies, including General Dynamics, Lockheed, LTV, E-Systems, and L3 Technologies, and used by the United States Air Force and Roya ...

Boeing CC-137 The Boeing CC-137 was a transport and tanker aircraft which served with the Canadian Forces from 1970 to 1997. The Boeing 707-347C aircraft provided long range passenger transport for the military, VIP transport for government and air-to-air r ...

** WC-135 * Boeing E-3 Sentry * Boeing VC-137B/C Stratoliner * Northrop Grumman E-8 Joint STARS *

Martin/General Dynamics RB-57F Canberra The Martin/General Dynamics RB-57F Canberra is a specialized strategic reconnaissance aircraft developed in the 1960s for the United States Air Force by General Dynamics from the Martin B-57 Canberra tactical bomber, which itself was a licen ...

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

References

Bibliography

External links

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

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 ...

1950s turbofan engines