View source for SPA 6A

{{short description|1910s Italian piston aircraft engine}}
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{|{{Infobox aircraft begin
| name=6A
| image=SPA 6A inline engine (2).JPG
| caption=S.P.A. 6A engine on display at the [[Gianni Caproni Museum of Aeronautics]]
}}{{Infobox Aircraft Engine
|type=Water-cooled [[Reciprocating engine|Piston]] [[Aircraft engine|aero engine]]
|manufacturer=[[S.P.A. (automobile)|Società Piemontese Automobili (S.P.A.)]], [[Ansaldo]], [[Società Italiana Ernesto Breda|Breda]], Talomona, Industrie Mecchaniche e Ferroviarie of [[Arezzo]]
|national origin=Italy
|first run=c.1916
|major applications=[[Ansaldo SVA]]
|produced=
|number built=3,000
|program cost=
|unit cost=
|developed from=
|variants with their own articles=
}}
|}
The '''SPA 6A''' is an Italian water-cooled inline six-cylinder [[Aircraft engine|aero engine]] of the [[World War I]] era.  The SPA 6A is mostly known for its use in the [[Ansaldo SVA]] high speed [[reconnaissance]] aircraft.<ref name="JanesairWW1">{{cite book  |title= Jane's Fighting Aircraft of World War I |year= 2001 |publisher=Random House |location= London|isbn = 1-85170-347-0|page=316}}</ref><ref name=":Museum">{{cite web |last=Caramanna |first=Giorgio |title=The Italian Air Force Museum of Vigna di Valle and its Engine Collection |url=https://www.enginehistory.org/Museums/IAFM/IAFM.shtml |access-date=May 13, 2023 |website=enginehistory.org}}</ref>
==Design and development==
The Societa Piemontese Automobili (SPA) of [[Turin]], Italy started building aircraft engines in 1908 and prior to 1916 had built [[Flat engine|flat]], [[V engine|vee]] and [[Radial engine|radial]] engines.  In 1916 SPA began manufacturing a [[straight-six engine]] known as the 6A.<ref name=":Angle1">{{cite book |last1=Angle |first1=Glenn D. |title=Airplane Engine Encyclopedia |url=https://archive.org/details/airplaneenginee00anglgoog |date=1921|publisher=The Otterbein Press|location=Dayton, Ohio|pages=462-464}}</ref>
The SPA 6A was designed with steel cylinders arranged in pairs with a common welded water jacket.  The type made use of relatively advanced features such as aluminium pistons and a 6 degree [[Valve timing|overlap in valve timing]].<ref name=":Angle1" />
The engine was ordered into mass production by the Italian Military Aviation Technical Division to equip the Ansaldo SVA aircraft.<ref name=":Museum" />  In addition to production by SPA, the 6A engine was manufactured by Ansaldo, Breda, Talomona and Industrie Mecchaniche e Ferroviarie of [[Arezzo]].<ref name=":Angle1" />
The Ansaldo SVA was one of the fastest aircraft of WW1 with a top speed of {{convert|230|km/h|mph|abbr=on|0}}.<ref name=":SVA">{{cite book |last1=Cattaneo |first1=Gianna|title=The S.V.A. (Ansaldo) Scouts - Profile Publications Number 61. |date=1966|publisher=Profile Publications Ltd.|location=Surrey, UK|pages=10}}</ref> During WW1, Anasaldo SVAs made a sensational [[flight over Vienna]] to drop [[propaganda]] leaflets.  Other famous exploits of the Ansaldo SVA included a 1920 [[Rome]]-[[Tokyo]] flight and a 1919 crossing of the [[Andes]].<ref name=":Museum" />
Around 3,000 SPA 6A engines were produced in three variants: normal, semi super-compressed and super-compressed.<ref name=":Museum" /><ref name=":Angle1" />  Engines of this type remained in service until the 1930s.<ref name=":Museum" />
==Variants==
;SPA 6A Normal: Originally rated for {{convert|150|hp|kW|abbr=on|0}} at 1,600 rpm with a displacement of {{convert|14.6|L|cuin|abbr=on|0}} and a weight of {{convert|240|kg|lbs|abbr=on|0}}.<ref name=":Angle1" /> Maximum power {{convert|201|hp|kW|abbr=on|0}}.<ref name=":Zampicinini">{{Cite book |last=Zampicinini |first=Franco |title=La collezione "Antonio Capetti" di motori alternativi per aeromobili |date=1994 |publisher=Politechnico di Torino |location=Turin, Italy |language=Italian |trans-title=The “Antonio Capetti” collection of reciprocating engines for aircraft |lccn=95222631}}</ref>
;SPA 6A Semi-Super-Compressed: Identical to the normal 6A, but with the cylinder bore increased to {{convert|137|mm|in|abbr=on|2}}, and with a capacity of {{convert|15.03|L|cuin|abbr=on|0}}. Rated for {{convert|210|hp|kW|abbr=on|0}} but could develop {{convert|235|hp|kW|abbr=on|0}} at 1,700 rpm.<ref name=":Angle1" />
;SPA 6-2-A Super-Compressed: Displacement {{convert|16.62|L|cuin|abbr=on|0}} bore increased to {{convert|140|mm|in|abbr=on|2}} bore and {{convert|180|mm|in|abbr=on|2}} stroke, with a weight of {{convert|270|kg|lbs|abbr=on|0}}. Rated at {{convert|250|hp|kW|abbr=on|0}} but could develop {{convert|310|hp|kW|abbr=on|0}} at 1,850 rpm.<ref name=":Angle1" />
==Applications==
*[[Ansaldo A.1 Balilla]]
*[[Ansaldo SVA]]
*[[Bartel BM.5]]
*[[Breda A.2]]
*[[Breda A.3]]
*[[Breda A.9|Breda A.9 and A.9bis]]
*[[CANT 7]]ter
*[[Caproni Ca.66]]
*[[Gabardini G.9]]
*[[SIAI S.50]]
==Specifications (6A Normal) ==
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{{pistonspecs|
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|ref=''Angle'' <ref name=":Angle1" />
|type=Inline six-cylinder piston engine
|bore=135 mm (5.31 in)
|stroke=170 mm (6.69 in)
|displacement={{convert|888.9|cuin|l|abbr=on|order=flip|2}}
|length=
|diameter=
|width=
|height=
|weight={{convert|255|kg|lbs|abbr=on}}
|valvetrain=SOHC, two valves per cylinder
|supercharger=
|turbocharger=
|fuelsystem=Twin  Zenith carburettors or one Duplex Zenith type 55-DC carburettor
|fueltype=
|oilsystem=[[Dry-sump]]
|coolingsystem=Water-cooled
|power={{convert|150|hp|kW|abbr=on||order=flip}} at 1,600 rpm (rated).<ref name=":Angle1" /> {{convert|200|hp|kW|abbr=on||order=flip}} at 1,600 rpm (maximum).<ref name=":Zampicinini" />
|specpower=
|compression=5.2:1
|fuelcon=
|specfuelcon={{cvt|0.288|kg/kWh|lb/hph|3}}
|oilcon={{cvt|0.02|kg/kWh|lb/hph|3}}
|power/weight={{cvt|0.267|hp/lb|kW/kg|order=flip}}
|designer=
|reduction_gear=Direct-drive
|general_other=
|components_other=Twin Marelli ignition magnetos
|performance_other=
}}
==See also==
{{aircontent
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|see also=
<!-- designs which were developed into or from this aircraft: -->
|related=
<!-- 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=
*[[Austro-Daimler 6]]
*[[BMW IIIa]]
*[[Hiero 6]]
*[[Liberty L-6]]
*[[Mercedes D.III]]
}}
==References==
{{Commons category}}
{{Reflist}}
[[Category:1910s aircraft piston engines]]
[[Category:Straight-six engines]]