This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: "Allison J33" – news · newspapers · books · scholar · JSTOR (July 2012) (Learn how and when to remove this message)
Allison J33 turbojet engine on display at Flugausstellung Hermeskeil
Type Turbojet
Manufacturer General Electric
Allison Engine Company
First run 1942
Major applications Lockheed P-80 Shooting Star
Lockheed T-33 Shooting Star
Lockheed F-94A/B Starfire
SSM-N-8 Regulus
Developed from General Electric J31

The General Electric/Allison J33 is an American centrifugal-flow jet engine, a development of the General Electric J31, enlarged to produce significantly greater thrust, starting at 4,000 lbf (18 kN) and ending at 4,600 lbf (20 kN) with an additional low-altitude boost to 5,400 lbf (24 kN) with water-alcohol injection.


The J33 was originally developed by General Electric as a follow-on to their work with the designs of Frank Whittle during World War II. Their first engine was known as the General Electric I-A, but after major changes to adapt it to US production and to increase thrust, it started limited production as the I-16 in 1942, the 16 referring to its 1,600 lbf (7.1 kN) thrust. Full production started as the J31 when the United States Army Air Forces introduced common naming for all their engine projects.

Along with the I-16, GE also started work on an enlarged version, known as the I-40. As the name implied, the engine was designed to provide 4,000 lbf (18 kN). Apart from size, the main difference between I-16 and the I-40 was the combustion system: the I-16 had ten reverse-flow cans, whereas the I-40 had 14 straight-through combustors. The development cycle was remarkably rapid. Design work started in mid-1943 and the first prototype underwent static testing on 13 January 1944.

Lockheed was in the midst of the XP-80 project at the time, originally intending to power their design with a US-produced version of the Halford H-1 of about 3,000 lbf (13 kN). Production of the H-1 by Allis-Chalmers ran into delays, and since the I-40 would dramatically improve performance, plans were made to fit the prototypes with the I-40 instead.

The I-40 became important to the USAAF's plans when the I-16 powered P-59 was skipped over in favor of the I-40 powered P-80 as the US's first production jet fighter. In 1945, the license to actually produce the engine was not given to General Electric, but to Allison instead. Allison, working largely from government-owned wartime factories, could produce the engine in quantity more quickly and cheaply.

By the time the production lines were shut down, Allison had built over 6,600 J33's and General Electric another 300 (mostly the early runs).

In 1958, surplus J33s were used in jet donkeys pushing dead loads at 200 knots to test aircraft carrier arresting gear cables and tailhooks at Lakehurst.[1]

A model of the J33 intended for civil use, designated the Allison 400-C4, in 1948 became the first US gas turbine certificated for commercial transport use.[2]


A J33 at the Finnish Air Force Museum
Allison J33 on display at the Museum of Aviation, Robins AFB

Data from: Aircraft engines of the World 1953,[3] Aircraft engines of the World 1957,[4] Aircraft engines of the World 1953,[5]

similar to -21 without water injection.[6]
4,600 lbf (20 kN), United States Navy (USN)
4,600 lbf (20 kN), (USN)
4,600 lbf (20 kN), (USN) Used as mixed propulsion engine system with P&W R-4360 on Martin P4M[5]
A short life engine powering the Chance-Vought Regulus, 4,600 lbf (20.46 kN) thrust.
Similar to the -16A, 5,850 lbf (26.02 kN)
Powering the Grumman F9F-7, 5,400 lbf (24.02 kN) thrust.
similar to -21 without water injection
A short life engine powering the Chance-Vought Regulus.
4,500 lbf (20.02 kN) thrust.
Powering the Lockheed T2V-1 with bleed air for boundary-layer control.
similar to -35, 4,600 lbf (20.46 kN) thrust.
6,100 lbf (27.13 kN) thrust, powers the Lockheed T2V.
6,100 lbf (27.13 kN) thrust, powers the Lockheed T2V.
similar to -35
United States Air Force (USAF), similar to the -16A,
8,200 lbf (36.48 kN) re-heat thrust.
similar to -35
6,000 lbf (26.69 kN) re-heat thrust.[5]
4,600 lbf (20.46 kN) thrust / 5,400 lbf (24.02 kN) with water-alcohol injection, powers the Lockheed T2V and Lockheed T-33.
A short life engine powering the Martin Matador, 4,600 lbf (20.46 kN) thrust.
Model 400-C4
Company designation, for commercial use, similar to J33-A-21.[2]
Model 400-C5
Company designation of J33-A-23.
Model 400-C13
Company designation of the -35
Model 400-D9
Company designation of the -33


Engines on display

Specifications (Allison J33-A-35)

Data from Jane's all the World's Aircraft 1955–56 and Aircraft engines of the World 1957.[8] [4]

General characteristics



Take-off thrust, static wet: 5,400 lbf (24 kN) at 11,750 rpm at sea level
Normal thrust, static: 3,900 lbf (17 kN) at 11,000 rpm at sea level

See also

Related development

Comparable engines

Related lists


  1. ^ Dempewolff, Richard F. (June 1958). "Jet "Donkeys" for the Jets". Popular Mechanics. Hearst Magazines. pp. 72–75.
  2. ^ a b "Here and There : U.S. Gas Turbine Approved by C.A.A". Flight and Aircraft Engineer. Llll (2059): 626. 10 June 1948.
  3. ^ Wilkinson, Paul H. (1953). Aircraft engines of the World 1953 (11th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 52–59.
  4. ^ a b Wilkinson, Paul H. (1957). Aircraft engines of the World 1957 (15th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 65–69.
  5. ^ a b c Wilkinson, Paul H. (1950). Aircraft engines of the World 1950 (11th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 46–47.
  6. ^ Wilkinson, Paul H. (1949). Aircraft engines of the World 1949 (7th ed.). London: Sir Isaac Pitman & Sons Ltd. p. 47.
  7. ^ "Engines List". City of Norwich Aviation Museum. Retrieved 29 August 2023.
  8. ^ Bridgman, Leonard (1955). Jane's all the World's Aircraft 1955–56. London: Jane's all the World's Aircraft Publishing Co. Ltd.

Further reading