|R-755 / L-4|
|Jacobs R-755 installed in a Boeing-Stearman Model 75|
|Manufacturer||Jacobs Aircraft Engine Company|
Design and development
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.
- The base-line direct drive production version.
- 300 hp variant.
- Similar to A1 but with Scintilla magnetoes.
- 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.
- Anahuac Tauro
- Avro Cadet
- Beechcraft Staggerwing
- Boeing-Stearman Model 75
- Cessna AT-17
- Cessna 195
- Funk F-23
- Grumman Ag Cat
- Kellett KD-1
- Morane-Saulnier MS-505
- Waco CG-15
- Waco Custom Cabin series (YKC, YKC-S etc.)
- Waco Standard Cabin series (YKS-6 etc.)
Engines on display
- A preserved Jacobs R-755 is on display at the Arkansas Air Museum.
- A restored Jacobs R-755A is on display at the House of Whitley.
- Type: 7-cylinder air-cooled radial piston engine
- Bore: 5.25 in (133 mm)
- Stroke: 5 in (130 mm)
- Displacement: 757 cu in (12.4 L)
- Length: 37 in (940 mm) overall
- Diameter: 43.5 in (1,100 mm)
- Dry weight: 505 lb (229 kg)
- Valvetrain: 2 valves per cylinder, pushrod-actuated, sodium-cooled exhaust valves
- Fuel system: Single Stromberg NA-R7A carburetor
- Fuel type: 73 octane
- Oil system: One pressure pump, two scavenge pumps
- Cooling system: Air-cooled
- Reduction gear: Direct drive, right hand tractor
- Power output: 225 hp (168 kW) at 2,000 rpm at sea level
- Specific power: 0.32 hp/cu-in (14.8 kW/L)
- Power-to-weight ratio: 0.48 hp/lb (0.8 kW/kg)
- Gunston, Bill (1989). World encyclopaedia of aero engines (Fully rev. 2nd ed.). Wellingborough: P. Stephens. p. 85. ISBN 1-85260-163-9.
- Bridgman, Leonard (1955). Jane's all the World's Aircraft 1955-56. London: Jane's all the World's Aircraft Publishing Co. Ltd. p. 305.
- Arkansas Air Museum - Jacobs R-755 Retrieved: 31 January 2009
- Bridgman, edited by Leonard (1989). Jane's fighting aircraft of World War II (1995 ed.). New York: Military Press. p. 305. ISBN 0-517-67964-7.
- Grey, C.G.; Bridgman, Leonard, eds. (1938). Jane's all the World's Aircraft 1938. London: Sampson Low, Marston & company, ltd. pp. 86d–87d.
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