Pobjoy P
{{short description|1920s British piston aircraft engine}}
| {{Infobox aircraft begin
|name='P' |image= |caption= }}{{Infobox Aircraft 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 = |program cost = |unit cost = |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.{{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=178ā179|edition=1. publ. in the UK.}}
Applications
Specifications (Pobjoy P)
{{pistonspecs
|
|ref=Jane's all the World's Aircraft 1928{{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=18dā19d}}
|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}}