Hispano-Suiza 24Y and 24Z

Surviving Type 82 prototype (Polish Aviation Museum)

Hispano-Suiza 24Y and 24Z are 24 cylinders engines with a H layout, developed before and during WWII by Hispano-Suiza in France.

24Y type 82

In 1936, the french Air Ministry issues a requierement for a new aircraft engine in the 2000 horsepower range, for a transatlantic flying boat projet. At this point in time, Hispano suiza was already producing its 12Y, a 1000 hp V12 used mostly in fighters. Thus, the company decided to use the 12Y as a basis for a 24 cylinders design. However, unlike Allison with its V-3420 and Daimler-Benz with its DB 606 a bit later, they didn't choose to assemble two V12's side-by-side on a common gearbox. Rather, while the cylinder banks were reused from the 12Y, with many parts remaining compatible, the whole engine was rearranged into a compact H layout. The engine is composed of two vertical Flat-12's, each having its crankshaft, on a common gearbox. Superchargers, cooling systems, pumps, and other systems were directly borrowed from the 12Y. A prototype was tested, but the development was suspended in favor of more pressing military need. The prototype was rediscovered in Poland after WWII ^[1] .

24Y type 90

This version was developed in parallel with the type 82. The difference was that it didn't join the power from both crankshafts into a single propellers. Rather, it was designed to drive contra-rotating propellers. The prototype disappeared during the war ^[1] .

24Z type 95

Work on this engine started in 1943, in Tarbes, where Hispano-Suiza's design team had been relocated. This design was similar to the Type 90, however, as the name suggest, it was no longer based on the 12Y, but on the 12Z, an more advanced version of the french V12 design featyuring 4 valves per cylinders, among other improvements. The engine was theoretically capable of 3600 hp. Its first intended application was the SNCASE SE.580 fighter. After the war, attempts were made to market the engine for civilian use, but without success. A prototype is preserved in the Musée de l'air et de l'espace ^[2] .

References

1. Lage, Manuel; Sánchez-Renedo, S. J.; Viejo, M. (2004). Hispano Suiza in aeronautics: men, companies, engines, and aircraft. Warrendale, Pa: SAE International. ISBN   978-0-768-00997-2.
2. Pearce, William (13 February 2016). "Hispano-Suiza 24Z (Type 95) Aircraft Engine". Old Machine Press.