Jacobs R-755 (company designation L-4) was a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States by the Jacobs Aircraft Engine Company. 
Design and development [ edit ]
The R-755 was first run in 1933 and was still in production in the 1970s. With a
bore and stroke of 5.25 in × 5 in (133 mm × 127 mm) the displacement 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 heads. An R-755E variant was developed for use in helicopters.
Variants [ edit ]
The base-line direct drive production version.
300 hp variant.
De-rated version of the R-755A to drive a fixed pitch airscrew.
De-rated version of the R-755A to drive a variable or controllable pitch airscrew.
Up-rated engine with reduction gearing.
Developed to power the Jacobs Type 104 Gyrodyne.
Applications [ edit ]
Engines on display [ edit ]
Specifications (R-755-A1) [ edit ]
Data from Jane's 
Type: 7-cylinder air-cooled radial piston engine
Bore: 5.25 in (133 mm)
Stroke: 5.0 in (127 mm)
Displacement: 757 cu in (12.4 L)
Length: 27.25 in (692 mm)
Diameter: 44 in (1,188 mm)
Dry weight: 505 lb (229 kg)
2 valves per cylinder, pushrod-actuated, Sodium cooled exhaust valves Valvetrain:
Fuel system: Single Stromberg NA-R7A carburetor
Fuel type: 73 octane
Oil system: One pressure pump, two scavenge pumps
Cooling system: Air-cooled
Direct drive, right hand tractor Reduction gear:
See also [ edit ]
References [ edit ]
^ Gunston 1989, p.85.
^ a b c d e Bridgman, Leonard (1955). Jane's all the World's Aircraft 1955-56. London: Jane's all the World's Aircraft Publishing Co. Ltd.
^ Arkansas Air Museum - Jacobs R-755 Retrieved: 31 January 2009
^ Janes 1989, p.305.
Bibliography [ edit ]
World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
Jane's Fighting Aircraft of World War II. London. Studio Editions Ltd, 1989. ISBN 0-517-67964-7
External links [ edit ]