# Jacobs R-915 > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Jacobs_R-915 > Markdown URL: https://mediated.wiki/source/Jacobs_R-915.md > Source: https://en.wikipedia.org/wiki/Jacobs_R-915 > Source revision: 1347778318 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Radial aircraft engine manufactured in the United States R-915 Type Radial engine Manufacturer Jacobs Aircraft Engine Company Developed from Jacobs R-755 The **Jacobs R-915** or **Jacobs L-6** is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States, production started in 1936.[1] ## Design and development The R-915 was effectively an enlargement of the [R-755](/source/Jacobs_R-755) with strengthened stressed parts.[2] With a [bore](/source/Bore_(engine)) and [stroke](/source/Stroke_(engine)) of 5.5 in × 5.5 in (140 mm × 140 mm), for a [displacement](/source/Engine_displacement) of 915 cu in (15 L). Take-off power was around 330 hp (250 kW). The engine features steel [cylinders](/source/Cylinder_(engine)) with aluminum-alloy [cylinder heads](/source/Cylinder_head). ## Variants **R-915A1** - Baseline variant; an enlarged [R-755](/source/Jacobs_R-755) **R-915A3** - Similar to the A1 but with Scintilla magnetoes **R-915A4** - With a power take-off for autogyros ## Applications - [Avro Anson Mk II and Mk III](/source/Avro_Anson) - [Beechcraft Model 18D](/source/Beechcraft_Model_18) - [Beechcraft F-17D Staggerwing](/source/Beechcraft_Staggerwing) - [Fleet 50](/source/Fleet_50) - [Howard DGA-15J](/source/Howard_DGA-15) - [Kellett KD-1](/source/Kellett_KD-1) - [Waco AQC, AGC, ARE, AVN](/source/Waco_Custom_Cabin_series) ## Engines on display - A preserved Jacobs R-915 is on display at the [Nanton Lancaster Society](https://en.wikipedia.org/w/index.php?title=Nanton_Lancaster_Society&action=edit&redlink=1).[3] - A Jacobs L-6 is on display at the [Canadian Museum of Flight](/source/Canadian_Museum_of_Flight)[4] ## Specifications (R-915A1) *Data from* Jane's[5] ### General characteristics - **Type:** 7-cylinder air-cooled radial piston engine - **[Bore](/source/Bore_(engine)):** 5.5 in (140 mm) - **[Stroke](/source/Stroke_(engine)):** 5.5 in (140 mm) - **[Displacement](/source/Engine_displacement):** 915 cu in (15 L) - **Length:** 40 in (1,030 mm) - **Diameter:** 45.5 in (1,160 mm) - **[Dry weight](/source/Dry_weight):** 555 lb (252 kg) ### Components - **[Valvetrain](/source/Valvetrain):** 2 valves per cylinder (pushrod-actuated); sodium cooled exhaust valves - **Fuel system:** Single [Stromberg](/source/Stromberg_carburettor) NA-R7A carburetor - **Fuel type:** 80 [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:** 330 hp (246 kW) at 2,200 RPM at sea level - **[Specific power](/source/Power_density):** 0.36 hp/cu-in (16.4 kW/L) - **[Compression ratio](/source/Compression_ratio):** 6:1 - **[Power-to-weight ratio](/source/Power-to-weight_ratio):** 0.6 hp/lb (1 kW/kg) ## See also **Related development** - [Jacobs R-755](/source/Jacobs_R-755) **Comparable engines** - [Armstrong Siddeley Cheetah](/source/Armstrong_Siddeley_Cheetah) - [Avia Rk.17](/source/Avia_Rk.17) - [Bristol Neptune](/source/Bristol_Neptune) - [Piaggio Stella P.VII](/source/Piaggio_Stella_P.VII) - [Wright R-760](/source/Wright_R-760) **Related lists** - [List of aircraft engines](/source/List_of_aircraft_engines) ## References ### Notes 1. **[^](#cite_ref-1)** Gunston 1989, p.85. 1. **[^](#cite_ref-AEotW50_2-0)** Wilkinson, Paul H. (1950). *Aircraft engines of the World 1950* (8th ed.). London: Sir Isaac Pitman & Sons Ltd. p. 161. 1. **[^](#cite_ref-3)** [Nanton Lancaster Society: Jacobs L-6 MB](http://www.bombercommandmuseum.ca/engine_jacobs.html) [Archived](https://web.archive.org/web/20150923193515/http://www.bombercommandmuseum.ca/engine_jacobs.html) 2015-09-23 at the [Wayback Machine](/source/Wayback_Machine) Retrieved: 23 July 2015 1. **[^](#cite_ref-4)** [The Canadian Museum of Flight - L-6](http://www.canadianflight.org/content/jacobs-l-6) Retrieved: 31 January 2009 1. **[^](#cite_ref-5)** Janes 1989, p.305. ### Bibliography - Gunston, Bill. *World Encyclopedia of Aero Engines*. Cambridge, England. Patrick Stephens Limited, 1989. [ISBN](/source/ISBN_(identifier)) [1-85260-163-9](https://en.wikipedia.org/wiki/Special:BookSources/1-85260-163-9) - *Jane's Fighting Aircraft of World War II*. London. Studio Editions Ltd, 1989. [ISBN](/source/ISBN_(identifier)) [0-517-67964-7](https://en.wikipedia.org/wiki/Special:BookSources/0-517-67964-7) ## External links Wikimedia Commons has media related to [Jacobs L-6](https://commons.wikimedia.org/wiki/Category:Jacobs_L-6). - [Jacobs L-6 MB](http://www.bombercommandmuseum.ca/engine_jacobs.html) [Archived](https://web.archive.org/web/20150923193515/http://www.bombercommandmuseum.ca/engine_jacobs.html) 2015-09-23 at the [Wayback Machine](/source/Wayback_Machine), Bomber Command Museum of Canada - Nanton Lancaster Society - [FAA Type Data Certificate Sheet - R-915](http://rgl.faa.gov/Regulatory_and_Guidance_library/rgMakeModel.nsf/0/eecd81771cb4808b862574cc004be28e/$FILE/E-195.pdf) 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-915](https://en.wikipedia.org/wiki/Jacobs_R-915) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Jacobs_R-915?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.