The Jacobs R-755 (company designation L-4) is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States by the

Jacobs Aircraft Engine Company The Jacobs Aircraft Engine Company was an American aircraft engine manufacturer that existed from 1926 to 1956. History Early years The Jacobs Aircraft Engine Company was formed in 1926 in Philadelphia. Later the company moved to Pottstown, Pe ...

Design and development

The R-755 was first run in 1933 and was still in production in the 1970s. With a bore and

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

of 5.25 in × 5 in (133 mm × 127 mm) the

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 ...

was 757 cu in (12.4 L), power ranged from 200 hp to 350 hp (150 kW - 260 kW). The engine features steel cylinders with aluminum-alloy

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ov ...

s. An R-755E variant was developed for use in helicopters.

Variants

;R-755A1:The base-line direct drive production version. ;R-755A2:300 hp variant. ;R-755A3:Similar to A1 but with Scintilla magnetoes. ;R-755B1:De-rated version of the R-755A to drive a fixed pitch airscrew. ;R-755B2:De-rated version of the R-755A to drive a variable or controllable pitch airscrew. ;R-755E:Up-rated engine with reduction gearing. ;R-755EH:Developed to power the Jacobs Type 104 Gyrodyne.

Applications

* Anahuac Tauro *

Beechcraft Model 17 Staggerwing The Beechcraft Model 17 Staggerwing is an American biplane with an atypical negative wing stagger (the lower wing is farther forward than the upper wing). It first flew in 1932. Development At the height of the Great Depression, aircra ...

(B17L, C17L, E17L) * Boeing-Stearman PT-18 Kaydet *

Cessna AT-17 Bobcat The Cessna AT-17 Bobcat or Cessna Crane is a twin-engine advanced trainer aircraft designed and made in the United States, and used during World War II to bridge the gap between single-engine trainers and larger multi-engine combat aircraft. The ...

Cessna 195 The Cessna 190 and 195 Businessliner are a family of light single radial engine powered, conventional landing gear equipped, general aviation aircraft which were manufactured by Cessna between 1947 and 1954.Montgomery, MR & Gerald Foste ...

Funk F-23 The Funk F-23 was an agricultural aircraft produced in the United States during the 1960s. It was designed by Donald Funk using the fuselage frame of military surplus Fairchild PT-23 trainers as a starting point. The resulting aircraft was a l ...

* Grumman G-164 Ag Cat *

Kellett KD-1 The Kellett KD-1 was a 1930s American autogyro built by the Kellett Autogiro Company. It had the distinction of being the first practical rotary-wing aircraft used by the United States Army and inaugurated the first scheduled air-mail service us ...

Lascurain Aura The Lascurain Aura was a prototype of a regional aircraft designed and built for Mexican engineer Angel Lascurain. It was the largest aircraft designed and built in Mexico. Development Lascurain wanted to manufacture an aircraft designed for t ...

* Morane-Saulnier MS.505 Criquet *

Waco F series The Waco F series is a series of American-built general aviation and military biplane trainers of the 1930s from the Waco Aircraft Company. Development The Waco 'F' series of biplanes supplanted and then replaced the earlier 'O' series of 1927 ...

(YMF, YPF) *

Waco Custom Cabin series The Waco Custom Cabins were a series of up-market single-engined four-to-five-seat cabin sesquiplanes of the late 1930s produced by the Waco Aircraft Company of the United States. "Custom Cabin" was Waco's own description of the aircraft which des ...

(YOC, YQC) *

Waco Standard Cabin series The Waco Standard Cabin series is a range of American single-engine 4–5 seat fabric covered cabin biplanes produced by the Waco Aircraft Company beginning in 1931 with the QDC and continuing until 1942 when production ended for the VKS-7F.Brandl ...

(YKC, YKC-S, YKS-6) * Waco PG-3 (twin-engined powered version of Waco CG-15 glider, prototype only)

Engines on display

* A preserved Jacobs R-755 is on display at the

Arkansas Air Museum The Arkansas Air & Military Museum is an aviation and military museum located at Drake Field in Fayetteville, Arkansas. It is the largest aviation museum in Arkansas. History The museum was originally established in 1986 as the Arkansas Air Museu ...

. * A Jacobs R-755 is on public display at the

Aerospace Museum of California The Aerospace Museum of California is a private non-profit aviation museum located in North Highlands, California, outside of Sacramento, California, on the grounds of the former McClellan Air Force Base. The museum has a 4.5-acre outdoor Air Park ...

*A preserved Jacobs R-755 is on display a
Super T Aviation Academy
in Medicine Hat, Canada. * A restored Jacobs R-755A is on display at the

House of Whitley A house is a single-unit residential building. It may range in complexity from a rudimentary hut to a complex structure of wood, masonry, concrete or other material, outfitted with plumbing, electrical, and heating, ventilation, and air condit ...

Specifications (R-755-A1)

References

External links

The Jacobs Engine - Nanton Lancaster Society

FAA Type Data Certificate Sheet - R-755

Jacobs Engine Powered Plymouth Truck
{{US military piston aeroengines 1930s aircraft piston engines Aircraft air-cooled radial piston engines Jacobs aircraft engines