{{short description|1920s British piston aircraft engine}} <!-- This article is a part of Wikipedia:WikiProject Aircraft. Please see Wikipedia:WikiProject Aircraft/page content for recommended layout. --> {{infobox aero engine |name='P' |image= |caption= |engine_type=Piston radial aero-engine |national_origin = United Kingdom |manufacturer = Pobjoy Airmotors |designer = Douglas Rudolf Pobjoy |first_run = ca.1926 |major_applications = |status = |produced = |number_built = |developed_from = |variants_with_their_own_articles = |developed_into = Pobjoy R }}

The '''Pobjoy P''' was a British seven-cylinder, air-cooled, aircraft engine designed by Douglas Rudolf Pobjoy and built by Pobjoy Airmotors. It became the progenitor of the Pobjoy R/Niagara/Cataract family of small radial engines. A notable feature of the Pobjoy P was the propeller reduction gear which allowed the small engine to operate at more desirable higher speeds.<ref name="Lumsden">{{cite book|last1=Lumsden|first1=Alec S.C.|title=British piston aero-engines and their aircraft|date=1994|publisher=Airlife Publ.|location=Shrewsbury|isbn=1-85310-294-6|pages=178–179|edition=1. publ. in the UK.}}</ref>

==Applications== * Comper C.L.A.7 Swift<ref name="Lumsden"/> * Parnall Imp<ref name="Lumsden"/> <!--==Engines on display==-->

== Specifications (Pobjoy P)== {{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 all the World's Aircraft 1928<ref name=JAWA1928>{{cite book |title=Jane's all the World's Aircraft 1928 |editor1-last=Grey |editor1-first=C.G. |year=1928 |publisher=Sampson Low, Marston & company, ltd |location=London |pages=18d–19d}}</ref> |type=7-cylinder air-cooled, radial, left-hand tractor |bore={{cvt|72|mm|order=flip|2}} |stroke={{cvt|87|mm|order=flip|2}} |displacement={{cvt|151.05|cuin|L|2}} |length= |diameter={{cvt|25|in}} |width= |height= |weight={{cvt|115|lb|2}} |valvetrain=overhead valves operated by rockers, push-rods and tappets driven by a cam-plate at the rear of the engine |supercharger= |turbocharger= |fuelsystem=One Zenith carburetor |fueltype=80% Petrol, 20% Benzol |oilsystem=Dry sump, pressure system at {{cvt|45|psi}} |coolingsystem=Air-cooled |power={{cvt|60|hp}} at 3,000 rpm rated output; {{cvt|67.5|hp}} at 3,300 rpm maximum |specpower={{cvt|0.397|hp/cuin|kW/L}} |compression= |fuelcon= |specfuelcon={{cvt|0.57|lb/hph|kg/kWh|order=flip}} |oilcon={{cvt|0.023|imppt/hph|L/kWh|order=flip}} |power/weight= {{cvt|0.522|hp/lb|kW/kg|order=flip}} |designer=Douglas Rudolf Pobjoy |reduction_gear=Double-helical spur gear 0.524:1

|general_other= |components_other= |performance_other= }}

==References== {{commons category|Pobjoy aircraft engines}} {{reflist}}

{{Pobjoy aeroengines}}

P Category:1920s aircraft piston engines Category:Aircraft air-cooled radial piston engines Category:Seven-cylinder engines