{{Short description|British aircraft engine}} {{For|the wrestling events|RAF 03|RAF 07}} <!-- This article is a part of Wikipedia:WikiProject Aircraft. Please see Wikipedia:WikiProject Aircraft/page content for recommended layout. --> {{infobox aero engine |name=RAF 3 |image=RAF 3a Napier MLP 04.jpg |caption=RAF 3a on display at the Polish Aviation Museum |engine_type=Piston inline aero engine |national_origin=United Kingdom |manufacturer=Royal Aircraft Factory |first_run=September 1914 |major_applications=Royal Aircraft Factory R.E.7 |number_built = 289 |developed_from = RAF 1 |developed_into = RAF 4 |variants_with_their_own_articles = }}

The '''RAF 3''' is a British liquid-cooled, V12 engine developed for aircraft use during World War I. Based on the eight–cylinder RAF 1 it was designed by the Royal Aircraft Factory but produced by the two British companies of Armstrong Whitworth and Napier & Son. The '''RAF 7''' was a high compression version of the same engine.<ref>Gunston, 1989, p. 156.</ref>

==Variants== ;RAF 3 :1914 - Prototype engine, 200 horsepower (150 kW). ;RAF 3a :1914 - Main production variant, increased bore, 260 horsepower (194 kW). 29 built by Armstrong Whitworth, 260 built by Napier & Son. ;RAF 7 :300 horsepower (224 kW) high compression version with high-lift camshafts.

==Applications== *Airco DH.4 *Royal Aircraft Factory R.E.7

==Specifications (RAF 3a)== {{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=''Lumsden''<ref>Lumsden 2003, p. 223.</ref> |type=12-cylinder, upright, 60-degree Vee engine |bore=4.5 in (114.3 mm) |stroke=5.5 in (140 mm) |displacement=1,049.4 cu in (17.24 L) |length= |diameter= |width= |height= |weight=780 lb (354 kg) |valvetrain=Overhead valve, both valves operated by a single pushrod |supercharger= |turbocharger= |fuelsystem= |fueltype= |oilsystem= |coolingsystem=Liquid-cooled |power=260 hp (194 kW) at 1,750 rpm (takeoff power) |specpower=0.25 hp/cu in (11.25 kW/L) |compression=5.3:1 |fuelcon= |specfuelcon= |oilcon= |power/weight=0.33 hp/lb (0.54 kW/kg)

|designer= |reduction_gear=0.5:1, left-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= *RAF 1 *RAF 4 <!-- 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= *Rolls-Royce Eagle *Rolls-Royce Falcon <!-- See WP:Air/PC for more explanation of these fields. --> }}

==References==

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

===Bibliography=== {{Commons category}} {{refbegin}} * Gunston, Bill. ''World Encyclopaedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. {{ISBN|1-85260-163-9}} * Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. {{ISBN|1-85310-294-6}}. {{refend}}

{{Royal Aircraft Factory aeroengines}}

Category:1910s aircraft piston engines Category:V12 aircraft engines Category:Liquid-cooled aircraft piston engines Category:Royal Aircraft Factory aircraft engines