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 Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

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 A cylinder () has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infinite ...

with aluminum-alloy

cylinder head In a piston engine, the cylinder head sits above the cylinders, forming the roof of the combustion chamber. In sidevalve engines the head is a simple plate of metal containing the spark plugs and possibly heat dissipation fins. In more modern ...

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

Engines on display

* A preserved Jacobs R-755 is on display at the Arkansas Air Museum. * 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 McClellan, California, outside of Sacramento, California, on the grounds of the former McClellan Air Force Base. History Founded as the Air Force Logistics Mus ...

*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.

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