SPA 6A

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.

Design and development
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.

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.

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

The Ansaldo SVA was one of the fastest aircraft of WW1 with a top speed of 230 km/h. 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.

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

Variants

 * SPA 6A Normal: Rated for 150 hp at 1,600 rpm with a displacement of 14.56 L and a weight of 255 kg.
 * SPA 6A Semi-Super-Compressed: Identical to the normal 6A but with the cylinder bore increased to 137mm. Rated for 200 hp but could develop 235 hp at 1,700 rpm.
 * SPA 6-2-A Super-Compressed: Displacement 16.62 L with a weight of 270 kg. Rated at 250 hp but could develop 310 hp at 1,850 rpm.

Applications

 * Ansaldo A.1 Balilla
 * Ansaldo SVA
 * Bartel BM.5
 * Breda A.2
 * Breda A.3
 * Breda A.9 and A.9bis
 * CANT 7ter
 * Caproni Ca.66
 * Gabardini G.9
 * SIAI S.50