Allison J35

A J35 with exhaust duct removed, exposing the power turbine.

The General Electric/Allison J35 was the United States Air Force's first axial-flow (straight-through airflow) compressor jet engine. Originally developed by General Electric (GE company designation TG-180) in parallel with the Whittle-based centrifugal-flow J33, the J35 was a fairly simple turbojet, consisting of an eleven-stage axial-flow compressor and a single-stage turbine. With the afterburner, which most models carried, it produced a thrust of Template:Convert.

Like the J33, the design of the J35 originated at General Electric, but major production was by the Allison Engine Company.

Design and developmentEdit

While developing the T31 axial turboprop in 1943 General Electric realized that they had the resources to design an axial flow turbojet at the same time as their centrifugal-flow J33 engine. They recognized the axial would have more potential for the future and went ahead with the TG-180 engine.<ref name=Gunston>Template:Cite book</ref> GE axial compressor designs were developed from the NACA 8-stage compressor.<ref name="NASAch3">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

File:GE-Allison-J35-Engine.jpg

Sectioned J35 at the National Naval Aviation Museum, Pensacola, FL. The 11-stage compressor is painted blue (the stators have been removed), the combustors are red, the turbine is unpainted. The teardrop-shaped openings along the outer edge of the turbine are the air channels used to cool the blades.

File:J-35-A-4 Turbojet Combustor Dome.jpg

Cutaway of J35 combustor dome

File:J-35-A-4 Turbojet Fuel Atomizer.jpg

Cutaway of J35 fuel atomizer

The engine had its starter and accessories (fuel control, fuel pump, oil pumps, hydraulic pump, RPM generator)<ref name="Flight110556p567">Template:Cite journal</ref> mounted in the center of the compressor inlet. This accessory layout, as used on centrifugal engines, restricted the area available for compressor inlet air. It was carried over to the J47 but revised (relocated to an external gearbox) on the J73 when a Template:Percentage increase in airflow was required.<ref name="Flight260757p111">Template:Cite journal</ref> It also had an inlet debris guard which was common on early jet engines.

GE developed a variable afterburner for the engine, although electronic control linked with engine controls had to wait until the J47.<ref name="General Electric Company">Template:Cite book</ref> Marrett describes one of the potential consequences of manual control of the engine and afterburner on a turbine engine: if the afterburner lit but the pilot failed to ensure the nozzle opened, the RPM governor could overfuel the engine until the turbine failed.<ref name="Marrett">Template:Cite book</ref>

Operational historyEdit

The General Electric J35 first flew in the Republic XP-84 Thunderjet in 1946. Late in 1947, complete responsibility for the development and production of the engine was transferred to the Allison Division of the General Motors Corporation and some J35s were also built by GM's Chevrolet division. More than 14,000 J35s had been built by the time production ended in 1955.

The J35 was used to power the Bell X-5 variable-sweep research aircraft and various prototypes such as the Douglas XB-43 Jetmaster, North American XB-45 Tornado, Convair XB-46, Boeing XB-47 Stratojet, Martin XB-48, and Northrop YB-49. It is probably best known, however, as the engine used in two of the leading fighters of the United States Air Force (USAF) in the 1950s: the Republic F-84 Thunderjet and the Northrop F-89 Scorpion.

A largely redesigned development, the J35-A-23, was later produced as the Allison J71, developing Template:Convert thrust.

VariantsEdit

Data from: Aircraft Engines of the World 1953,<ref name="Wilkinson">Template:Cite book</ref> Aircraft Engines of the World 1950<ref name="AEotW50">Template:Cite book</ref>

J35-GE-2: Template:Convert thrust, prototypes built by General Electric.
J35-GE-7: Template:Convert thrust, built by General Electric, powered the 2 Republic XP-84 Thunderjet prototypes
J35-GE-15: Template:Convert thrust, built by General Electric, powered the sole Republic XP-84A Thunderjet
J35-A-3: Template:Convert thrust
J35-C-3: Template:Convert thrust, production by Chevrolet.
J35-C-3: Template:Convert thrust, production by Chevrolet.
J35-A-4: Similar to -29, Template:Convert thrust
J35-A-5: Template:Convert thrust
J35-A-9: Template:Convert thrust
J35-A-11: Similar to -29, Template:Convert thrust
J35-A-13: Template:Convert thrust
J35-A-13C
J35-A-15: Similar to -29, Template:Convert thrust, powered the 15 Republic YP-84 Thunderjets
J35-A-15C: Template:Convert thrust
J35-A-17: Similar to -29, Template:Convert thrust
J35-A-17A: Similar to -29, Template:Convert thrust
J35-A-17D: Template:Convert thrust
J35-A-19: Similar to -17, Template:Convert thrust
J35-A-21: Similar to -35, Template:Convert thrust, Template:Convert with afterburner
J35-A-21A: Similar to -35, Template:Convert thrust, Template:Convert with afterburner
J35-A-23: Similar to -29, Template:Convert thrust, original designation for the Allison J71
J35-A-25: Similar to -29, Template:Convert thrust
J35-A-29: Template:Convert thrust
J35-A-33: Similar to -35, Template:Convert thrust, Template:Convert with afterburner, without anti-icing
J35-A-33A: Similar to -35, Template:Convert thrust, Template:Convert with afterburner, without anti-icing
J35-A-35: Template:Convert thrust, Template:Convert with afterburner
J35-A-41: Similar to -35, Template:Convert thrust, Template:Convert with afterburner, with anti-icing
Model 450: company designation for J35 series engines.
General Electric 7E-TG-180-XR-17A: ca Template:Cvt gas power, gas generator for the Hughes XH-17.