The SPA 6A is an Italian water-cooled inline six-cylinder 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.[1][2]

6A
S.P.A. 6A engine on display at the Gianni Caproni Museum of Aeronautics
Type Water-cooled Piston aero engine
National origin Italy
Manufacturer Società Piemontese Automobili (S.P.A.), Ansaldo, Breda, Talomona, Industrie Mecchaniche e Ferroviarie of Arezzo
First run c.1916
Major applications Ansaldo SVA
Number built 3,000

Design and development

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The Societa Piemontese Automobili (SPA) of Turin, Italy started building aircraft engines in 1908 and prior to 1916 had built flat, vee and radial engines. In 1916 SPA began manufacturing a straight-six engine known as the 6A.[3]

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 overlap in valve timing.[3]

The engine was ordered into mass production by the Italian Military Aviation Technical Division to equip the Ansaldo SVA aircraft.[2] In addition to production by SPA, the 6A engine was manufactured by Ansaldo, Breda, Talomona and Industrie Mecchaniche e Ferroviarie of Arezzo.[3]

The Ansaldo SVA was one of the fastest aircraft of WW1 with a top speed of 230 km/h (143 mph).[4] 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.[2]

Around 3,000 SPA 6A engines were produced in three variants: normal, semi super-compressed and super-compressed.[2][3] Engines of this type remained in service until the 1930s.[2]

Variants

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SPA 6A Normal
Originally rated for 150 hp (112 kW) at 1,600 rpm with a displacement of 14.6 L (891 cu in) and a weight of 240 kg (529 lb).[3] Maximum power 201 hp (150 kW).[5]
SPA 6A Semi-Super-Compressed
Identical to the normal 6A, but with the cylinder bore increased to 137 mm (5.39 in), and with a capacity of 15.03 L (917 cu in). Rated for 210 hp (157 kW) but could develop 235 hp (175 kW) at 1,700 rpm.[3]
SPA 6-2-A Super-Compressed
Displacement 16.62 L (1,014 cu in) bore increased to 140 mm (5.51 in) bore and 180 mm (7.09 in) stroke, with a weight of 270 kg (595 lb). Rated at 250 hp (186 kW) but could develop 310 hp (231 kW) at 1,850 rpm.[3]

Applications

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Specifications (6A Normal)

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Data from Angle [3]

General characteristics

Components

  • Valvetrain: SOHC, two valves per cylinder
  • Fuel system: Twin Zenith carburettors or one Duplex Zenith type 55-DC carburettor
  • Oil system: Dry-sump
  • Cooling system: Water-cooled
  • Reduction gear: Direct-drive
  • Twin Marelli ignition magnetos

Performance

See also

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Comparable engines

Related lists

References

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  1. ^ Jane's Fighting Aircraft of World War I. London: Random House. 2001. p. 316. ISBN 1-85170-347-0.
  2. ^ a b c d e Caramanna, Giorgio. "The Italian Air Force Museum of Vigna di Valle and its Engine Collection". enginehistory.org. Retrieved May 13, 2023.
  3. ^ a b c d e f g h i Angle, Glenn D. (1921). Airplane Engine Encyclopedia. Dayton, Ohio: The Otterbein Press. pp. 462–464.
  4. ^ Cattaneo, Gianna (1966). The S.V.A. (Ansaldo) Scouts - Profile Publications Number 61. Surrey, UK: Profile Publications Ltd. p. 10.
  5. ^ a b Zampicinini, Franco (1994). La collezione "Antonio Capetti" di motori alternativi per aeromobili [The “Antonio Capetti” collection of reciprocating engines for aircraft] (in Italian). Turin, Italy: Politechnico di Torino. LCCN 95222631.