Pratt & Whitney J57

Pratt & Whitney J57
Pre-production copy of the J57
Type:	Turbojet engine
Design country:	United States
Manufacturer:	Pratt & Whitney
Production time:	1952 to 1965
Number of pieces:	21,170

The J57 is a turbojet engine that the American manufacturer Pratt & Whitney developed for the US Air Force at the end of the 1940s and which was also built in large numbers for the civilian market until 1965 under the name JT3 .

Development history

Pratt & Whitney had already manufactured jet engines during the Second World War, but only third-party developments such as the Rolls-Royce Nene under license for armaments production. From 1946 the company invested heavily in the development of its own second-generation jet engine. The aim was to double the thrust over the current models ( General Electric J33 , Westinghouse J34 ) to 10,000 pounds (44.5 kN).

In March 1947, Pratt & Whitney began developing its JT3. The engineers adopted the principle of two coaxial shafts from their design for the PT4 propeller turbine (military name: T45). This construction, with a low-pressure compressor and turbine on one shaft and a high-pressure compressor and turbine on the second shaft, formed the basis for the model's success. It offered higher performance with reduced consumption and years later even enabled the further development of the turbofan engine ( JT3D / TF33 ).

On October 21, 1948, the US Air Force proposed the JT3 for the motorization of the planned new B-52 bomber, until then the T45 turboprop was intended. The Westinghouse J40 came into question as a competitor model . Pratt & Whitney abandoned development of the T45 in January 1949 in favor of the JT3, which at that time was given the military designation J57. In June 1949, the Air Force ordered two prototypes XJ57-P-1 (JT3-10A, including: JT3A) and led from 1 to 2 August 1949 a mockup -Inspection at its headquarters Hartford , Connecticut , by. As a result, Pratt & Whitney presented a revised version on August 15, 1949 (XJ57-P-3 / JT3-10B). The procurement department of the US Air Force reported on December 6, 1949 of a contract for the delivery of 18 test copies of the YJ57-P-3 from May 1951. On December 13, 1949, the J57 finally defeated the J40 as a drive for the B- 52 through.

The first engine test runs took place in 1950, and on March 8, 1951, the maiden flight of a J57 under the wing of a B-50 bomber followed. The US Air Force reaffirmed in November 1951 that the delivery of the B-52 program had priority over the Convair YB-60 , a B-36 converted for jet propulsion , which was also dependent on the new, powerful engines. Finally, on April 15, 1952, the first flight of the B-52 with eight YJ57-P-3 took place.

Launch of three B-52G using the J57's water injection.

In the versions intended for this purpose (recognizable by the W in the type designation), a short-term increase in performance of around 15 percent was achieved through water injection , for example for the start. Negative side effects were greater noise and thick, black exhaust plumes.

For use in combat aircraft , Pratt & Whitneys equipped the J57 with an afterburner , which increased the maximum thrust to 87.2 kN.

The J57 is one of the first products in industrial series production in which titanium was used as a material. The first version of this kind was the J57-P-9W in 1955, which made it around 115 kilograms (six percent) lighter. However, due to poor material and processing quality, there were failures, only the successor model -19W worked satisfactorily in mid-1956. By the end of the 1950s, the titanium content rose to 266 kilograms (around 15 percent of the weight) in the J57-P-43W, mainly distributed over the air inlet, compressor housing and blades.

In 1958 Pratt & Whitney began developing the JT3C / J57 into a turbofan engine with the designation JT3D (TF33 in the US armed forces).

Pratt & Whitney's chief developer Leonard S. Hobbs received the Collier Trophy in 1952 for the development of the JT3 / J57 , an award given annually in the USA for advances in aerospace technology.

Pratt & Whitney built a total of 21,170 JT3 / J57 turbojet engines from 1951 to 1965.

use

In addition to the Boeing B-52 and the Convair YB-60, the J57 served as a drive for other aircraft of the US Air Force and Navy: The various versions of the Boeing C-135 family (including Boeing KC-135 , Boeing RC-135 ), North American F-100 , McDonnell F-101 , Convair F-102 , Martin B-57 , Lockheed U-2 , Bell X-16 , Douglas A-3 D, Douglas F4D , Douglas F5D , Vought F8U and the cruise missile SM- 62 Snark .

In the civil sector, this type of engine was first used under the manufacturer name JT3C from 1954 on the Boeing 367-80 , and later in the early versions of the Boeing 707 , Boeing 720 and Douglas DC-8 .

Technical specifications

Parameter	YJ57-P-3 (first pre-production model, 1950)	J57-P-59WB (water injection, 1959)
length	4.65 m	4.30 m
diameter	1.04 m	1.0 m
Dry weight	1990 kg	1755 kg
Thrust (maximum)	38.7 kN	61.2 kN
Compression of the compressor	11.6: 1	12.5: 1
Specific fuel consumption (at maximum thrust)	85.6 kg / kN h (0.84 lb / lbf h)	96.8 kg / kN h (0.95 lb / lbf h)

Web links

Commons : Pratt & Whitney J57  - Collection of Images, Videos and Audio Files

• The J57 in the USAF Museum