Fiat AS.6
The Italian 1931 Schneider Trophy entrant, the Macchi M.C.72, required an engine of 2,300 horsepower (1,700 kW) with the capability of producing up to 2,800 horsepower (2,090 kW) while having a weight of not more than 840 kilograms (1,850 lb). The contract was awarded to Fiat, but their most powerful V engine to that date was the 1,000-horsepower (750 kW) 12-cylinder Fiat AS.5 that had also been used for Schneider Trophy racing. The solution was to couple two AS.5 engines in tandem to produce a V-24 with each engine independently driving one of a pair of contra-rotating propellers through co-axial shafts. The rear engine drove the front propeller through a reduction gearbox, located between the two engines, up to a shaft that passed between the cylinder banks of the reverse-mounted forward engine. The latter's crankshaft drive faced rearwards and drove the rearmost propeller in a likewise manner, but instead via a hollow shaft through which the rear engine driveshaft passed. A large rear-mounted supercharger was used to boost the engine, with the fuel/air mixture being delivered to the cylinders through a manifold that was centrally mounted between the cylinder banks of both engines.
Applications
Specifications: AS.6
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