{{short description|Radial aircraft engine manufactured in the United States}} <!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout. --> {{infobox aero engine |name= R-915 |image =File:Jacobs engine, BT-13 - Evergreen Aviation & Space Museum - McMinnville, Oregon - DSC00478.jpg |caption = |engine_type= [[Radial engine]] |national_origin = |manufacturer= [[Jacobs Aircraft Engine Company]] |first_run= |major_applications= |number_built = |developed_from = [[Jacobs R-755]] |developed_into = |variants_with_their_own_articles = }}

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.<ref>Gunston 1989, p.85.</ref>

==Design and development== The R-915 was effectively an enlargement of the [[Jacobs R-755|R-755]] with strengthened stressed parts.<ref name=AEotW50>{{cite book |last=Wilkinson |first=Paul H. |title=Aircraft engines of the World 1950 |year=1950 |publisher=Sir Isaac Pitman & Sons Ltd. |location=London |edition=8th |page=161}}</ref> With a [[Bore (engine)|bore]] and [[Stroke (engine)|stroke]] of {{convert|5.5|x|5.5|in|mm|abbr=on}}, for a [[Engine displacement|displacement]] of {{convert|915|cuin|L|0|abbr=on}}. Take-off power was around {{convert|330|hp|kW|abbr=on}}. The engine features steel [[Cylinder (engine)|cylinders]] with aluminum-alloy [[cylinder head]]s.

==Variants== ;R-915A1:Baseline variant; an enlarged [[Jacobs R-755|R-755]] ;R-915A3:Similar to the A1 but with Scintilla magnetoes ;R-915A4:With a power take-off for autogyros

==Applications== * [[Avro Anson|Avro Anson Mk II and Mk III]] * [[Beechcraft Model 18|Beechcraft Model 18D]] * [[Beechcraft Staggerwing|Beechcraft F-17D Staggerwing]] * [[Fleet 50]] * [[Howard DGA-15|Howard DGA-15J]] * [[Kellett KD-1]] * [[Waco Custom Cabin series|Waco AQC, AGC, ARE, AVN]]

==Engines on display== *A preserved Jacobs R-915 is on display at the [[Nanton Lancaster Society]].<ref>[http://www.bombercommandmuseum.ca/engine_jacobs.html Nanton Lancaster Society: Jacobs L-6 MB] {{Webarchive|url=https://web.archive.org/web/20150923193515/http://www.bombercommandmuseum.ca/engine_jacobs.html |date=2015-09-23 }} Retrieved: 23 July 2015</ref> *A Jacobs L-6 is on display at the [[Canadian Museum of Flight]]<ref>[http://www.canadianflight.org/content/jacobs-l-6 The Canadian Museum of Flight - L-6] Retrieved: 31 January 2009</ref>

==Specifications (R-915A1)== {{pistonspecs| <!-- If you do not understand how to use this template, please ask at [[Wikipedia talk:WikiProject Aircraft]] --> <!-- Please include units where appropriate (main comes first, alt in parentheses). If data are missing, leave the parameter blank (do not delete it). For additional lines, end your alt units with )</li> and start a new, fully-formatted line with <li> --> |ref=Jane's<ref>Janes 1989, p.305.</ref> |type=7-cylinder air-cooled radial piston engine |bore=5.5 in (140 mm) |stroke=5.5 in (140 mm) |displacement=915 cu in (15 L) |length=40 in (1,030 mm) |diameter=45.5 in (1,160 mm) |width= |height= |weight=555 lb (252 kg) |valvetrain=2 valves per cylinder (pushrod-actuated); sodium cooled exhaust valves |supercharger= |turbocharger= |fuelsystem= Single [[Stromberg carburettor|Stromberg]] NA-R7A carburetor |fueltype=80 [[Octane rating|octane]] |oilsystem= One pressure pump, two scavenge pumps |coolingsystem=Air-cooled |power=330 hp (246 kW) at 2,200 RPM at sea level |specpower=0.36 hp/cu-in (16.4 kW/L) |compression=6:1 |fuelcon= |specfuelcon= |oilcon= |power/weight=0.6 hp/lb (1 kW/kg) |designer= |reduction_gear=Direct drive, right hand tractor |general_other= |components_other= |performance_other= }}

==See also== {{aircontent <!-- other related articles that have not already linked: --> |see also=

<!-- designs which were developed into or from this aircraft: --> |related= *[[Jacobs R-755]] <!-- aircraft that are of similar role, era, and capability this design: --> |similar aircraft=

<!-- relevant lists that this aircraft appears in: --> |lists= * [[List of aircraft engines]]

<!-- For aircraft engine articles. Engines that are of similar to this design: --> |similar engines= *[[Armstrong Siddeley Cheetah]] *[[Avia Rk.17]] *[[Bristol Neptune]] *[[Piaggio Stella P.VII]] *[[Wright R-760]] <!-- See [[WP:Air/PC]] for more explanation of these fields. --> }}

==References==

===Notes=== {{reflist}}

===Bibliography=== {{refbegin}} *Gunston, Bill. ''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}} {{refend}}

==External links== {{Commonscat|Jacobs L-6}} *[http://www.bombercommandmuseum.ca/engine_jacobs.html Jacobs L-6 MB] {{Webarchive|url=https://web.archive.org/web/20150923193515/http://www.bombercommandmuseum.ca/engine_jacobs.html |date=2015-09-23 }}, Bomber Command Museum of Canada - Nanton Lancaster Society *[http://rgl.faa.gov/Regulatory_and_Guidance_library/rgMakeModel.nsf/0/eecd81771cb4808b862574cc004be28e/$FILE/E-195.pdf FAA Type Data Certificate Sheet - R-915]

{{Jacobs aeroengines}} {{US military piston aeroengines}}

[[Category:1930s aircraft piston engines]] [[Category:Aircraft air-cooled radial piston engines]] [[Category:Jacobs aircraft engines]] [[Category:Seven-cylinder engines]]