Hispano-Suiza 12Y

The Hispano-Suiza 12Y was an aircraft engine produced by Hispano-Suiza for the French Air Force in the pre-WWII period. The 12Y became the primary French 1,000 hp (750 kW) class engine and was used in a number of famous aircraft, including the Morane-Saulnier M.S.406 and Dewoitine D.520.

Type V-12 piston aero engine
National origin France
Manufacturer Hispano-Suiza
First run 1932
Major applications Dewoitine D.520

Ikarus IK-2

Morane-Saulnier MS.406

Developed from Hispano-Suiza 12X
Developed into Hispano-Suiza 12Z

Its design was based on the earlier and somewhat smaller, 12X. The 12X did not see widespread use before the 12Y replaced it, and became one of the most powerful French designs of the immediate pre-WWII era. A further development was underway, the 12Z, but this effort ended due to the German occupation of France.

The 12Y was also produced under Hispano-Suiza licence in the Soviet Union as the Klimov M-100. This design later spawned the highly successful Klimov VK-105 series that powered the Yakovlev and Lavochkin fighters as well as the Petlyakov Pe-2 bomber. Licensed production of the early models was also undertaken in Czechoslovakia as the Avia HS 12Ydrs, and in Switzerland as the HS-77.

Design and development

Early development

The 12Y was a fairly traditional in construction, a 36-litre water-cooled V-12 with the two cast aluminium cylinder banks set at 60 degrees to each other. The cylinder heads were not removable, instead both cylinder banks could be quickly removed from the crankcase section of the engine. This made it somewhat famous for being leak-proof, a design feature that was considered by other designers and almost became a part of the Rolls-Royce Merlin.

The major design change from the earlier 12X was to use a master-articulated connecting rod system, instead of the fork-and-blade type. A single overhead camshaft (SOHC) drove the valves, which were filled with liquid sodium for cooling. Only a single intake and exhaust valve were used, unlike most designs of the era which had moved to three or four valves per cylinder. A single-stage, single-speed supercharger was standard, although the art of designing a useful intake was not as well developed as in other countries, and high altitude performance was always lacking.

The first 12Y test articles were constructed in 1932, and almost immediately the entire French aviation industry started designing around it. At the time the engine developed only 760 hp (570 kW), but it was clear it had potential to the 1,000 hp (750 kW) class. An early modification led to the Hispano-Suiza 12Ycrs which used a hollow propeller shaft to allow a 20 mm cannon to fire through the propeller spinner (a combination known as a moteur-canon). All later versions shared this feature. The 12Ydrs was the next major series, with a basic rating of 836 hp (623 kW) at sea level with a compression ratio of 5.8:1.

The Armée de l'Air changed their nomenclature, so the next version was the Hispano-Suiza 12Y-21, which increased the compression ratio to 7:1, when running on 100 octane gasoline. This boosted power to 867 hp (647  kW). In 1936 the connecting rod design was changed slightly to create the 12Y-31, but the lower 5.8:1 compression ratio was retained and the power was increased only slightly over the drs model to 850 hp (630 kW). Nevertheless, this became one of the most used engine designs of the pre-war era, used in almost all French fighter designs and prototypes.

Late variants

A real effort to improve the performance of the engine in 1938 resulted in the Hispano-Suiza 12Y-45, which used the S-39-H3 supercharger co-designed by André Planiol and Polish engineer Joseph Szydlowski. The Szydlowski-Planiol device was larger, but much more efficient than the indifferent Hispano-Suiza models. When used with 100 octane fuel, the supercharger boosted to the -21's 7:1, increasing power to 900 hp (670 kW). Combined with the fully adjustable Ratier propeller, this allowed the D.520 to perform as well as contemporary designs from Germany and England.

Another improvement in supercharging led to the Hispano-Suiza 12Y-49, whose performance improved from 850 hp (630 kW) at sea level to 920 hp (690 kW) at just over 10,000 ft (3,000 m). This improvement in power with altitude was a common feature of most engines of the era, the result of the supercharger "robbing" power at low altitudes while not boosting the power due to the possibility of detonation.

The final major version was the 1,085 hp (809 kW) Hispano-Suiza 12Y-51, which had just started into production at the time of the Armistice with Germany. The -51 was the first version that came close to the performance limits of the engine, although the single-stage supercharging meant that it was unable to compete with designs from England and Germany above 15,000 ft (5,000 m).

Foreign derivatives

In the early 1930s the Czechoslovakian Republic gained rights to build a license version of the HS-12Y. This was produced by Avia (Škoda) at Prag - Čakovice. The engine was intended to become the standard powerplant of all Czech military aircraft. Both the HS-12Ycrs and HS-12Ydrs were built in quantity and were more commonly known by these names rather than any Czech designation. Aircraft powered by these engines included the Avia B-34, Avia B-534, Avia B-71, Avia B-35, Avia B-135 and Rogožarski IK-3 .

Switzerland license built and assembled several different versions of the basic 12Ycrs for use in several aircraft: the reconnaissance biplane the EKW C-35, the multipurpose EKW C-36, the Swiss assembled D-3800 copy of the French M.S. 406 fighter and Swiss built versions of the French M.S.412 fighter called the D.3801. Saurer developed the engine further after the Fall of France into the YS-2 and YS-3 engines. These were used in more powerful follow-on versions of the same basic French fighter design, the M.S.450 called the D.3802 and then the final version called the D.3803.

In the mid-1930s, Russian engineer Vladimir Klimov was sent to France to obtain a license for local production of the 12Y. A series of design changes were added to cope with cold weather operation, and the engine entered production in 1935 as the Klimov M-100 with about 750 hp (560 kW).[1] However a series of continual upgrades increased the allowable RPM from the 12Y's fairly low 2,400 to 2,700, thereby increasing power to 1,100 hp (820 kW). The resulting design, the Klimov M-105 (VK-105) became one of the major Soviet engine designs during the war, powering all Yakovlev fighters.


Tabulated data from Lage 2004[2]

Type 73 Hispano 12Y engines. V-12, bore=150 mm, stroke=170 mm, capacity=36.0 litres. Type 77 with 20 mm Hispano-Suiza HS.404 cannon between cylinder banks, firing through propeller shaft.
Model Year Compression Power (hp) @ r.p.m. T-O power (hp) Output reduction Supercharger optimum altitude (m) Weight (kg) Cannon (y/n) Comments
12Ybr 650 hp19326.47852,2007851.50415nRated power (650 hp) less than nominal 785 hp
12Ygrs 650 hp19325.88502,4008001.54,000430nRated power (650 hp) less than nominal 850 hp
12Ydr19346.48002,2008001.50440nAs 12Ybr, variable-pitch propeller, left turning. For this and all later entries in both tables, Rated power = Nominal power = Power
12Ydrs19345.88602,4008351.54,000470nAs 12Ybrs, variable-pitch propeller, left turning
12Ydrs119345.88802,4008901.52,400470nVariable-pitch propeller, left turning
12Ydrs219345.89302,4009921.5900470nVariable-pitch propeller, left turning
12Yfrs19345.88602,4008351.54,000470nAs 12Ydrs, right turning
12Yfrs119345.88802,4008901.52,400470nAs 12Ydrs1, right turning
12Yfrs219345.89302,4009921.5900470nAs 12Ydrs, right turning
12Y-2519355.88602,4009431.53,600nAs 12Ydrs, variable ignition timing
12Y-2619355.89002,4009501.8850483opposite rotation to -27
12Y-2719355.89002,4009501.8850483opposite rotation to -26
12Y-287.29202,4009100.67:13,600475yLH rotation
12Y-297.29202,4009100.67:13,600475yIdentical to -28 but RH rotation
12Y-3019365.88602,4008300.67:13,250468yRedesigned connecting rods,LH rotation
12Y-3119365.88602,4008300.67:13,250468yIdentical to -30 but RH rotation
12Y-3219365.89602,4009550.67:12,300468yRedesigned connecting rods,LH rotation
12Y-3319365.89602,4009550.67:12,300468yIdentical to -32 but RH rotation
12Y-3619367.09602,4001,0500.55:11,250483yLH rotation
12Y-3719367.09602,4001,0500.55:11,250483yIdentical to -36 but RH rotation
12Y-3819367.010002,4001.53,400nLH rotation
12Y-3919367.010002,4001.53,400nIdentical to -38 but RH rotation
12Y-457.09202,4009350.67:14,200ySzydlowsky-Planiol (SP) supercharger
12Y 497.09102,4009100.67:15,250y(SP) supercharger, variable ignition timing
12Y-5019397.01,0002,5001,1000.67:13,260492y(SP) supercharger LH rotation
12Y-5119397.01,0002,5001,1000.67:13,260492yIdentical to -50 but RH rotation
Model Year Compression Power (hp) @ r.p.m. T-O power (hp) Output reduction Supercharger optimum altitude (m) Weight (kg) Cannon (y/n) Comments
Hispano-Suiza 12Z

Licence built variants

Avia HS 12Y
Klimov VK-100
Klimov VK-103 746 kW (1,000 hp)
Klimov VK-103A 820 kW (1,100 hp) at 2,000 m (6,600 ft)
Klimov VK-104
Klimov VK-105P 820 kW (1,100 hp) at take-off
Klimov VK-106 1,007 kW (1,350 hp) at take-off
Klimov VK-107 1,342 kW (1,800 hp) at take-off
Hispano-Suiza HS-77
12 Ycrs


Klimov powered

Specifications (12Ycrs)

Data from Le Dewoitine D.520[5][6]

General characteristics

  • Type: Twelve-cylinder supercharged liquid-cooled 60° V12 engine
  • Bore: 150 mm (5.906 in)
  • Stroke: 170 mm (6.693 in)
  • Displacement: 36.05 l (2,199.9 in³)
  • Length: 1,722 mm (67.8 in)
  • Width: 764 mm (30.08 in)
  • Height: 935 mm (36.81 in)
  • Dry weight:
  • 12Y-25:475 kg (1,047 lb)
  • 12Y-45:515 kg (1,135 lb)



  • Power output:
  • 12Y 25: 810 CV (600 kW) (800 hp) at 2,400 rpm for takeoff
  • 920 CV (680 kW) (910 hp) at 2,520 rpm at 3,600 m (11,800 ft)
  • 12Y 45: 850 CV (630 kW) (840 hp) at 2,400 rpm for takeoff
  • 935 CV (688 kW) (922 hp) at 2,520 rpm at 4,200 m (13,800 ft)
  • Specific power: 17.08 kW/l (0.38 hp/in³)
  • Compression ratio: 12Y 25: 7.2-1 12Y 45: 7-1
  • Specific fuel consumption: 328 g/(kW•h) (0.54 lb/(hp•h))
  • Oil consumption: 11 g/(kW•h) (0.28 oz/(hp•h))
  • Power-to-weight ratio: 1.32 kW/kg (0.8 hp/lb)

See also

Comparable engines

Related lists



  1. Kotelnikov 2005, p. 136.
  2. Lage, 2004, p.486-7
  3. Gunston 1989
  4. Lage, 2004, pp.258-260
  5. Danel and Cuny 1966, pp. 245-248.
  6. Hispano-Suiza 12Y-47 Retrieved: 1 October 2010.


  • Danel, Raymond and Jean Cuny. Docavia n°4: le Dewoitine D.520 (in French). Paris: Editions Larivière, 1966.
  • Kotelnikov, Vladimir. Russian Piston Aero Engines. Marlborough, Wiltshire. The Crowood Press Ltd. 2005. ISBN 1-86126-702-9.
  • Hispano-Suiza 12Y-47 Retrieved: 1 October 2010.
  • Wilkinson, Paul H.. Aircraft Engines of the World 1945. Paul H. Wilkinson. New York. 1945
  • Gunston, Bill. World Encyclopedia of Aero engines fully revised second edition. Patrick Stephens Limited. Wellingborough. 1989. ISBN 1-85260-163-9
  • Lage, Manual (2004). Hispano Suiza in Aeronautics. Warrendale, USA: SAE International. pp. 486–7. ISBN 0-7680-0997-9.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.