Jacobs R-755
225 hp radial aircraft engine
title: "Jacobs R-755" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["1930s-aircraft-piston-engines", "aircraft-air-cooled-radial-piston-engines", "jacobs-aircraft-engines"] description: "225 hp radial aircraft engine" topic_path: "general/1930s-aircraft-piston-engines" source: "https://en.wikipedia.org/wiki/Jacobs_R-755" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary 225 hp radial aircraft engine ::
::data[format=table title="infobox aero engine"]
| Field | Value |
|---|---|
| name | R-755 / L-4 |
| image | File:Radial Engine EASM 4Feb2010 (14568077736) (cropped).jpg |
| caption | Jacobs R-755 on display at the Evergreen Aviation & Space Museum |
| engine_type | Radial engine |
| manufacturer | Jacobs Aircraft Engine Company |
| first_run | 1933 |
| :: |
|name= R-755 / L-4 |image = File:Radial Engine EASM 4Feb2010 (14568077736) (cropped).jpg |caption = Jacobs R-755 on display at the Evergreen Aviation & Space Museum |engine_type= Radial engine |national_origin = |manufacturer= Jacobs Aircraft Engine Company |first_run=1933 |major_applications= |number_built = |developed_from = |developed_into = |variants_with_their_own_articles =
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.
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.
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
::figure[src="https://upload.wikimedia.org/wikipedia/commons/d/d1/Waco_YQC-6_N15705_(6235199366).jpg" caption="Waco YQC-6"] ::
- Anahuac Tauro
- Beechcraft Model 17 Staggerwing (B17L, C17L, E17L)
- Boeing-Stearman PT-18 Kaydet
- Cessna AT-17 Bobcat
- Cessna 195
- Funk F-23
- Grumman G-164 Ag Cat
- Kellett KD-1
- Lascurain Aura
- Morane-Saulnier MS.505 Criquet
- Waco F series (YMF, YPF)
- Waco Custom Cabin series (YOC, YQC)
- Waco Standard Cabin series (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.
- A Jacobs R-755 is on public display at the Aerospace Museum of California
- A preserved Jacobs R-755 is on display at 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)
and start a new, fully-formatted line with -- |ref=Jane's fighting aircraft of World War II, Jane's all the World's Aircraft 1938 |type=7-cylinder air-cooled radial piston engine |bore=5.25 in |stroke=5 in |displacement=757 cu in (12.4 L) |length=37 in overall |diameter=43.5 in |width= |height= |weight=505 lb |valvetrain=2 valves per cylinder, pushrod-actuated, sodium-cooled exhaust valves |supercharger= |turbocharger= |fuelsystem= Single Stromberg NA-R7A carburetor |fueltype=73 octane |oilsystem= One pressure pump, two scavenge pumps |coolingsystem=Air-cooled |power=225 hp at 2,000 rpm at sea level |specpower=0.32 hp/cu-in (14.8 kW/L) |compression= |fuelcon= |specfuelcon= |oilcon= |power/weight=0.48 hp/lb (0.8 kW/kg) |designer= |reduction_gear=Direct drive, right hand tractor |general_other= |components_other= |performance_other=
References
References
- (1989). "World encyclopaedia of aero engines". P. Stephens.
- Bridgman, Leonard. (1955). "Jane's all the World's Aircraft 1955-56". Jane's all the World's Aircraft Publishing Co. Ltd..
- [http://www.arkairmuseum.org/engines/engine-jacobs755.php Arkansas Air Museum - Jacobs R-755] {{Webarchive. link. (2010-12-03 Retrieved: 31 January 2009)
- [http://www.houseofwhitley.com/shop/binoculars-and-historical-artifacts/aviation/jacobs-r-755a-7-cylinder-air-cooled-radial-engine-with-3-blade-prop/] Retrieved: March 2017
- (1989). "Jane's fighting aircraft of World War II". Military Press.
- (1938). "Jane's all the World's Aircraft 1938". Sampson Low, Marston & company, ltd.
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