The Jacobs Aircraft Engine Company was an American

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 ...

manufacturer that existed from 1926 to 1956.

History

Early years

The Jacobs Aircraft Engine Company was formed in 1926 in

Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...

. Later the company moved to

Pottstown, Pennsylvania Pottstown is a Borough (Pennsylvania), borough in Montgomery County, Pennsylvania, United States. Pottstown was laid out in 1752–53 and named Pottsgrove in honor of its founder, John Potts (Pennsylvanian), John Potts. The old name was abando ...

after purchasing the machine workshop of the Light Manufacturing and Foundry Company.

Early engines

An early product was the 1931 L-3, a three-cylinder

air-cooled Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. Air-cooled designs are far simpler than their liquid-cooled ...

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

. Only 44 were built. By

1933 Events January * January 11 – Australian aviator Sir Charles Kingsford Smith makes the first commercial flight between Australia and New Zealand. * January 17 – The United States Congress votes in favour of Philippines independen ...

, Jacobs had developed its most famous engine, the L-4 seven-cylinder air-cooled radial, with a power rating of

displacement Displacement may refer to: Physical sciences Mathematics and physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of . It was better known as by its military designation, R-755. At the time it became known as the best producer of engines in the 200-400 horsepower range. Jacobs was the first to start making engines using forged

aluminum alloy An aluminium alloy ( UK/IUPAC) or aluminum alloy ( NA; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There ...

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder (engine), cylinder a ...

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

-filled exhaust

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, ...

, and

magnesium alloy Magnesium alloys are mixtures of magnesium (the lightest structural metal) with other metals (called an alloy), often aluminium, zinc, manganese, silicon, copper, rare earths and zirconium. Magnesium alloys have a hexagonal lattice structur ...

crankcase A crankcase is the housing in a reciprocating engine, piston engine that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, res ...

s. The L-4 was used mostly on the Cessna Bobcat, Cessna 195, and Stearman Kaydet. Due to the tendency of the L-4 engine to vibrate heavily at low rpm, it was given the nicknames ''Shakin' Jake'' and ''Shakey Jake''.

Later models

Later developments included the 285 hp L-5 or R-830, and 330 hp L-6 or R-915.

Postwar

Jacobs was acquired by Republic Industries in 1945, which was in turn acquired by Barium Steel Corporation in 1946. However in 1947, the company was sold back to Albert Jacobs. Jacobs Aircraft Engines went into default in 1950 and was again sold back to Republic. Finally, Barium sold the company in December 1956 and it closed a few months later in 1957.

Applications

Jacobs engines were fitted to many US-built aircraft of the inter-war period, including several

Waco Waco ( ) is a city in and the county seat of McLennan County, Texas, United States. It is situated along the Brazos River and I-35, halfway between Dallas and Austin. The city had a U.S. census estimated 2024 population of 146,608, making i ...

models. They were in use in 26 different countries including in Canada, where 330 horsepower L6-MB engines were used to power the Royal Canadian Air Force's Avro Anson Mk. II aircraft. In 1941 the American War Department gave the contract to Jacobs to produce Pratt & Whitney R-985 and R-1340 engines until 1945. Jacobs ranked 87th among United States corporations in the value of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

military production contracts. Peck, Merton J. & Scherer, Frederic M. ''The Weapons Acquisition Process: An Economic Analysis'' (1962)

Harvard Business School Harvard Business School (HBS) is the graduate school, graduate business school of Harvard University, a Private university, private Ivy League research university. Located in Allston, Massachusetts, HBS owns Harvard Business Publishing, which p ...

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Products

References

{{Jacobs aeroengines Manufacturing companies established in 1929 Manufacturing companies based in Philadelphia Defunct aircraft engine manufacturers of the United States 1929 establishments in Pennsylvania