# Jacobs R-755 > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Jacobs_R-755 > Markdown URL: https://mediated.wiki/source/Jacobs_R-755.md > Source: https://en.wikipedia.org/wiki/Jacobs_R-755 > Source revision: 1347778249 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) 225 hp radial aircraft engine R-755 / L-4 Jacobs R-755 on display at the Evergreen Aviation & Space Museum Type Radial engine Manufacturer Jacobs Aircraft Engine Company First run 1933 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](/source/Jacobs_Aircraft_Engine_Company).[1] ## Design and development The R-755 was first run in 1933 and was still in production in the 1970s. With a [bore](/source/Bore_(engine)) and [stroke](/source/Stroke_(engine)) of 5.25 in × 5 in (133 mm × 127 mm) the [displacement](/source/Engine_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](/source/Cylinder_(engine)) with aluminum-alloy [cylinder heads](/source/Cylinder_head). An **R-755E** variant was developed for use in helicopters. ## Variants **R-755A1** - The base-line direct drive production version.[2] **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.[2] **R-755B2** - De-rated version of the R-755A to drive a variable or controllable pitch airscrew.[2] **R-755E** - Up-rated engine with reduction gearing.[2] **R-755EH** - Developed to power the Jacobs Type 104 Gyrodyne.[2] ## Applications [Waco YQC-6](/source/Waco_Custom_Cabin_series) - [Anahuac Tauro](/source/Anahuac_Tauro) - [Beechcraft Model 17 Staggerwing](/source/Beechcraft_Model_17_Staggerwing) (B17L, C17L, E17L) - [Boeing-Stearman PT-18 Kaydet](/source/Boeing-Stearman_Model_75) - [Cessna AT-17 Bobcat](/source/Cessna_AT-17_Bobcat) - [Cessna 195](/source/Cessna_195) - [Funk F-23](/source/Funk_F-23) - [Grumman G-164 Ag Cat](/source/Grumman_Ag_Cat) - [Kellett KD-1](/source/Kellett_KD-1) - [Lascurain Aura](/source/Lascurain_Aura) - [Morane-Saulnier MS.505 Criquet](/source/Morane-Saulnier_MS.505_Criquet) - [Waco F series](/source/Waco_F_series) (YMF, YPF) - [Waco Custom Cabin series](/source/Waco_Custom_Cabin_series) (YOC, YQC) - [Waco Standard Cabin series](/source/Waco_Standard_Cabin_series) (YKC, YKC-S, YKS-6) - [Waco PG-3](/source/Waco_CG-15) (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](/source/Arkansas_Air_Museum).[3] - A Jacobs R-755 is on public display at the [Aerospace Museum of California](/source/Aerospace_Museum_of_California) - A preserved Jacobs R-755 is on display at [Super T Aviation Academy](https://www.supertaviation.ca) in Medicine Hat, Canada. - A restored Jacobs R-755A is on display at the [House of Whitley](https://en.wikipedia.org/w/index.php?title=House_of_Whitley&action=edit&redlink=1). ## Specifications (R-755-A1) *Data from* Jane's fighting aircraft of World War II,[4] Jane's all the World's Aircraft 1938[5] ### General characteristics - **Type:** 7-cylinder air-cooled radial piston engine - **[Bore](/source/Bore_(engine)):** 5.25 in (133 mm) - **[Stroke](/source/Stroke_(engine)):** 5 in (130 mm) - **[Displacement](/source/Engine_displacement):** 757 cu in (12.4 L) - **Length:** 37 in (940 mm) overall - **Diameter:** 43.5 in (1,100 mm) - **[Dry weight](/source/Dry_weight):** 505 lb (229 kg) ### Components - **[Valvetrain](/source/Valvetrain):** 2 valves per cylinder, pushrod-actuated, sodium-cooled exhaust valves - **Fuel system:** Single Stromberg NA-R7A carburetor - **Fuel type:** 73 [octane](/source/Octane_rating) - **Oil system:** One pressure pump, two scavenge pumps - **Cooling system:** Air-cooled - **[Reduction gear](/source/Propeller_speed_reduction_unit):** Direct drive, right hand tractor ### Performance - **Power output:** 225 hp (168 kW) at 2,000 rpm at sea level - **[Specific power](/source/Power_density):** 0.32 hp/cu-in (14.8 kW/L) - **[Power-to-weight ratio](/source/Power-to-weight_ratio):** 0.48 hp/lb (0.8 kW/kg) ## See also **Comparable engines** - [Armstrong Siddeley Cheetah](/source/Armstrong_Siddeley_Cheetah) - [Wright R-760](/source/Wright_R-760) **Related lists** - [List of aircraft engines](/source/List_of_aircraft_engines) ## References 1. **[^](#cite_ref-Gunston_1-0)** Gunston, Bill (1989). *World encyclopaedia of aero engines* (Fully rev. 2nd ed.). Wellingborough: P. Stephens. p. 85. [ISBN](/source/ISBN_(identifier)) [1-85260-163-9](https://en.wikipedia.org/wiki/Special:BookSources/1-85260-163-9). 1. ^ [***a***](#cite_ref-JAWA5556_2-0) [***b***](#cite_ref-JAWA5556_2-1) [***c***](#cite_ref-JAWA5556_2-2) [***d***](#cite_ref-JAWA5556_2-3) [***e***](#cite_ref-JAWA5556_2-4) 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. 1. **[^](#cite_ref-3)** [Arkansas Air Museum - Jacobs R-755](http://www.arkairmuseum.org/engines/engine-jacobs755.php) [Archived](https://web.archive.org/web/20101203082656/http://www.arkairmuseum.org/engines/engine-jacobs755.php) 2010-12-03 at the [Wayback Machine](/source/Wayback_Machine) Retrieved: 31 January 2009 1. **[^](#cite_ref-BridgmanFAoWWII_4-0)** Bridgman, Leonard, ed. (1989). *Jane's fighting aircraft of World War II* (1995 ed.). New York: Military Press. p. 305. [ISBN](/source/ISBN_(identifier)) [0-517-67964-7](https://en.wikipedia.org/wiki/Special:BookSources/0-517-67964-7). 1. **[^](#cite_ref-JAWA1938_5-0)** Grey, C.G.; Bridgman, Leonard, eds. (1938). *Jane's all the World's Aircraft 1938*. London: Sampson Low, Marston & company, ltd. pp. 86d–87d. ## External links Wikimedia Commons has media related to [Jacobs R-755](https://commons.wikimedia.org/wiki/Category:Jacobs_R-755). - [The Jacobs Engine - Nanton Lancaster Society](https://web.archive.org/web/20080609180228/http://www.lancastermuseum.ca/s,jacobsengine.html) - [FAA Type Data Certificate Sheet - R-755](http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8fe9769e3e0192fc8525670c006cc54c/$FILE/ATTH0K0R/TC121.pdf) [Archived](https://web.archive.org/web/20170901152345/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8fe9769e3e0192fc8525670c006cc54c/$FILE/ATTH0K0R/TC121.pdf) 2017-09-01 at the [Wayback Machine](/source/Wayback_Machine) - [Jacobs Engine Powered Plymouth Truck](http://autoweek.com/article/classic-cars/jay-leno-welcomes-cessna-powered-plymouth-his-garage?) v t e Jacobs aircraft engines Radial engines R-755/L-4 R-830/L-5 R-915/L-6 v t e United States military piston aircraft engine designation system H (four-bank H-configuration inline) H-1640 XH-2240 XH-2470 XH-2600 XH-3130 XH-3730 H-4070 IV (inverted-V inline) IV-1430 IV-2040 IV-2220 L (single-bank inline) L-330 L-365 L-375 L-390 L-410 L-440 L-510 L-825 O (opposed) O-15 O-40 O-45 O-90 O-100 O-145 O-150 O-170 O-175 O-180 O-190 O-200 (C) O-200 (F) O-205 O-235 O-290 O-300 O-335 O-360 (C) O-360 (L) O-405 O-425 O-435 O-470 O-480 O-520 O-540 (F) O-540 (L) O-550 O-580 O-805 O-1230 R (radial) R-250 R-265 R-270 R-370 (LB) R-370 (K) R-420 R-440 R-500 R-540 (W) R-540 (K) R-545 R-550 R-600 R-670 R-680 R-720 R-755 R-760 R-790 R-830 R-915 R-975 DR-980 R-985 R-1044 R-1300 R-1340 R-1454 R-1510 R-1535 R-1640 R-1670 R-1690 R-1740 R-1750 R-1820 R-1830 R-1860 R-2000 R-2060 R-2160 R-2180 R-2600 R-2800 R-3350 R-4090 R-4360 R-7755 V (upright-V inline) V-720 V-1150 V-1237 V-1400 V-1440 V-1460 V-1510 V-1560 V-1570 V-1650 (P) V-1710 V-1950 V-3420 V (inverted-V inline) V-770 V-1650 (L) VG (inverted-V inline) VG-1410 W (three-bank W-configuration inline) W-2779 See also: X-1800 US military gas turbine aeroengines Piston engine configurations --- Adapted from the Wikipedia article [Jacobs R-755](https://en.wikipedia.org/wiki/Jacobs_R-755) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Jacobs_R-755?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.