View source for Avia Rk.12

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{|{{Infobox aircraft begin
| name=Rk.12
| image=
| caption=
}}{{Infobox Aircraft Engine
|type=Seven-cylinder air-cooled radial
|manufacturer=Avia (Avia akciova spolecnost pro prumysl letecky), [[Prague]]
|designer=
|national origin=[[Czechoslovakia]]
|first run=
|major applications=
|produced=
|number built=
|program cost=
|unit cost=
|developed from=
|variants with their own articles=
}}
|}
One of [[Avia Motors|Avia]]'s own designs, the 1930s '''Avia Rk.12''' was a seven-cylinder [[radial engine]] with a rated output of 150&nbsp;kW (200&nbsp;hp), built in Czechoslovakia.
==Design and development==
As well as producing aircraft and building [[Hispano-Suiza]] and [[Lorraine-Dietrich|Lorraine]] aero-engines under licence, Avia also designed and built their own radial engines.  Their Rk.12 was a seven-cylinder [[supercharger|supercharged]] model, rated at 200&nbsp;hp.<ref name="JAWA38"/>
It was a conventional air-cooled radial: nitrided steel barrels with integral fins were screwed into heat-treated [[Y alloy]] heads.  The [[piston]]s were also of heat-treated Y alloy.  The [[crankcase]] was cast from aluminium alloy, with some minor parts using magnesium alloy.  The single-throw, two-piece [[crankshaft]] was linked to the pistons with an I-section Y alloy [[master rod]], with a single-piece big end, which carried the other six [[piston rod]]s.<ref name="JAWA38"/>
<!-- ==Operational history== -->
<!--==Variants== -->
==Applications==
*[[Avia 51]]
==Specifications==
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{{pistonspecs
|ref=Jane's All the World's Aircraft 1938<ref name="JAWA38"/>
|type=Seven-cylinder air-cooled radial
|bore=130 mm (5.12 in)
|stroke=130 mm (5.12 in)
|displacement=12.08 L (737 cu in)
|length=1,047.5 mm (41.24 in)
|diameter=1,110 mm (43.7 in
|weight=dry, with ancillaries, without propeller hub 215.5 kg (475 lb)
|valvetrain=one inlet and one exhaust valve per cylinder, operated by push rods via rocker gear.  Six cam push rod disc drive.
|supercharger=impeller drive ratio 10.7:1
|turbocharger=
|fuelsystem=single barrel [[Zenith Carburetters|Zenith 70P]] or Stromberg NAR68 carburettor
* '''Ignition system: '''Scintilla magnetos, automatic advance
|fueltype=petrol, 74 Octane
|oilsystem=dry sump, with one pressure and one scavenging pump
|coolingsystem=air-cooled
|power='''rated''', maintained to 3,000 m (9,840 ft), at 2,200 rpm: 150 kW (200 hp)
*'''Power output: maximum continuous''' 195 kW (260 hp)
*'''Power output: take-off''' 210 kW (280 hp)
|specpower=
|compression=5.3:1
|fuelcon=62 L/hr (13.64 Imp gal/h, 16.4 US gal/h)
|specfuelcon=
|oilcon=at cruising speed, 2 kg/h (4.4 lbs/h)
|power/weight=
|designer=
|reduction_gear=direct drive
|general_other=
|components_other=
|performance_other=
}}
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{{aircontent
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|related=<!-- related developments -->
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==References==
{{Reflist|refs=
<ref name="JAWA38">{{cite book |title= Jane's All the World's Aircraft 1938|last= Grey |first= C.G. |year=1972|publisher= David & Charles|location= London|isbn=0-7153-5734-4|page=31d }}</ref>
}}
<!-- ==External links== -->
{{Avia aeroengines}}
[[Category:1930s aircraft piston engines]]
[[Category:Aircraft air-cooled radial piston engines]]