Hispano-Suiza 12N
| Company type | Subsidiary |
|---|---|
| Industry | Aerospace, Automotive |
| Founded | 1928 |
| Headquarters | France |
| Products | Aircraft engines |
The Hispano-Suiza 12N represented one of two novel V-12 engine configurations introduced in 1928 and produced by the French subsidiary of Hispano-Suiza for use by the Armée de l’Air. Delivering approximately , this engine was pioneering in its application of gas nitride surface hardening and the incorporation of wet cylinder liners within Hispano-Suiza’s aircraft powerplants. Notably, it powered the inaugural non-stop flight connecting Europe and the United States.
Design and development
Prior to 1927, Hispano-Suiza’s powerplants evolved from their World War I era V-8 Hispano-Suiza 8. During 1927–1928, the manufacturer unveiled four new engines: a pair of V-12 types alongside two six-cylinder inline variants. The Hispano-Suiza 12N, also known as Type 61, was the larger V-12 with a displacement of , whereas the smaller 12M offered less capacity. Despite size differences, both engines shared numerous design characteristics; the 12M debuted in 1927, followed by the 12N in 1928.
These engines featured a 60° V configuration with carburettors, intake, and exhaust systems positioned on their outer sides. Each cylinder bank was served by three carburettors, each supplying fuel to a pair of cylinders. A significant advancement was the adoption of wet liner technology—borrowed from Hispano’s automotive engines—where cooling water directly contacted steel cylinder liners instead of circulating through aluminium jackets. This innovation enhanced cooling efficiency, eased assembly procedures, and permitted increased bore diameters without altering cylinder spacing. The liners were open-ended and threaded near the top for secure attachment to the engine block; valve seats were integrated into aluminium cylinder heads. Extending into the crankcase, these liners simplified manufacturing and assembly processes as the block and crankcase were fastened together.
Both the 12M and 12N introduced gas nitriding for surface hardening of cylinder walls within Hispano-Suiza’s lineup, decreasing wear and minimizing oil consumption. They incorporated an advanced cooling system for main bearings that improved lubricant circulation without necessitating high oil pump speeds.
These models also featured easily attachable or detachable epicyclic gearing; prior Hispano-Suiza engines had fixed gear ratios tied to specific variants. Integration of gearing added approximately in weight. By 1935, the 12Ner version included an electrically controlled variable pitch propeller operable during flight.
The development of the 12N series culminated in the supercharged 12Y (Type 73) engine, which first ran in 1932.
Operational history
The Hispano-Suiza 12Nb powered the Breguet XIX Point d'Interrogation during its historic first non-stop east-to-west crossing from Paris to New York in September 1930, marking a pivotal achievement in transatlantic aviation history.
Throughout the early 1930s, the 12N engines saw extensive deployment in flying boats operating on French routes across the Atlantic and Africa, attesting to their dependability in both commercial and military aviation sectors.
The Swiss government’s KTA (War Technical Department) secured manufacturing licenses for the 12Nb, leading to production of eighty units at the Saurer truck factory in 1932—a testament to international industrial cooperation.
Variants
Information sourced from Hispano Suiza in Aeronautics.
- 12Nb/650
- Features a compression ratio of 6.2, delivering maximum power at 2,100 rpm.
- 12Nbr/650
- Maintains a compression ratio of 6.2 with peak power output at 2,100 rpm. Equipped with gearing options of 2:1 or 1.61:1.
- 12Ns
- Offers a compression ratio of 7 and nominal power at 2,200 rpm. Engineered specifically for the 1928 Schneider Cup competition.
- 12Nsr
- Incorporates a compression ratio of 10, providing nominal power at 2,400 rpm. Designed for the 1931 Schneider Cup, featuring a Farman supercharger.
- 12Nc
- Utilizes a compression ratio of 6.2 and nominal power at 2,000 rpm. Installed in the Ford 14A Trimotor aircraft.
- 12Ncr
- 12Ndr
- Equipped with an electrically adjustable pitch propeller and rotates counter-clockwise (1935 model).
- 12Ner
- A refined version of the 12Ndr, incorporating articulated connecting rods.
- 12Nfr
- Comparable to the Ndr variant but rotates clockwise.
- 12Ngr
- Similar to the Ner model with clockwise rotation.