Hispano-Suiza 8 - Variants

Variants

8A (HS-8A)

The first model of the Hispano-Suiza 8 produced in any quantity.

8Aa (HS-8Aa)

The HS-8Aa, which entered production in July 1915, was the production variant of the basic HS-8A type, with increased power output: 150 hp (110 kW) at 2,000 rpm. Early HS-8A engines were plagued with various problems which required further work. The 150 hp HS-8Aa was the standard powerplant for early-production SPAD VIIs. The demand for the Hispano-Suiza engine was such that other manufacturers began producing it under license, in France, Great Britain (Wolseley Adder), Italy (Nagliati in Florence and Itala/SCAT in Turin) and Russia. Total production of the HS-8Aa amounted to some 6,000 engines. To avoid the problems experienced by the 8A, Wolseley reduced the compression ratio to 4.7 in the Adder.

8Ab (HS-8Ab)

The HS-8Ab was yet another evolution of the HS-8A. By increasing the compression ratio from 4.7 to 5.3, Birkigt was able to increase the power output to 180 hp (132 kW) at 2,100 rpm. The HS-8Ab began replacing the 8Aa on SPAD VIIs in early 1917.

Hispano-Suiza 8Ac (HS-8Ac)

8B (HS-8B)

The HS-8Ab had been plagued by engine failures due to the high compression ratio: piston heads were sometimes pierced and seized the engine. To further increase the power output of the engine, Birkigt chose to increase engine speed.

8Ba (HS-8Ba)

The first, the HS-8Ba, kept the 4.7 compression ratio of the HS-8Aa but delivered 200 hp (147 kW) at 2,300 rpm.

8Ba (HS-8Bb)

The second version, the HS-8Bb, had a compression ratio of 5.3. A reduction gear (3:4 ratio) was fitted to compensate for the increased engine speed. However the reduction gear system was fragile, and often broke down, sometimes with spectacular results ending up with the entire propeller, driveshaft and driven gear parting company from the airframe. Progressive refinement of the engine brought the available power to 235 hp by the end of 1917.

The HS-8B was used to power the earliest versions of the S.E.5a, all examples of the SPAD S.XII and SPAD S.XIII, front-line versions of the Sopwith Dolphin and several other Allied aircraft types, with its gear reduction easily identifiable in vintage World War I photos, from its use of a clockwise rotation propeller.

8Ba (HS-8Be)

8Ca (HS-8Ca)

The HS-8Ca, a gear-reduction equipped powerplant with a resultant clockwise rotation propeller like the 8B, produced 220 hp at 2,100 rpm. It had a manually loaded 37 mm Puteaux cannon mounted between the cylinder banks (a so-called moteur-canon) that could fire a single shot at a time through the hollow drive shaft without propeller interference. The engine was used on the SPAD S.XII.

8F (HS-8F)

The HS-8F was basically an enlarged version of the HS-8B, and was intended for use in bombers. Displacement rose to 18.5 liters (1,127.3 in3), with a power of 300 hp (220 kW) at 2,100 rpm (eq. 750 lb·ft torque). Despite the increased weight of 256 kg (564 lb), the HS-8F was installed in fighters such as the Nieuport-Delage NiD 29 and Martinsyde Buzzard, and it would have powered the never-produced Mk.II version of the Sopwith Dolphin. Engine speed being lower than that of the HS-8B, the reduction gear was deleted, thereby increasing engine reliability.

8Fa (HS-8Fa)

8Fb (HS-8Fb)

8Fd (HS-8Fd)

Wolseley W.4B Adder I

Wolseley W.4B Adder II

Wolseley W.4B Adder III

Wolseley W.4A Python I

Wolseley W.4A Python II

Wolseley W.4A Viper

Was an improved 8A. Wolseley's engineers removed problems with the crankshaft and increased the compression ratio to give more power. It did not need the reduction gearing of the H-S8.

Wolseley W.4A Viper II

The Viper II could deliver 210 hp at 2,000 rpm.

Wright-Hisso A

Wright-Hisso E

The American Wright-Martin aviation firm license-produced the original 150 hp HS-8Aa engine as the Wright-Hispano E, for use in World War I combat aircraft to be built in the United States – it found its way into the JN-4H version of the Curtiss Jenny, replacing the Curtiss OX-5 liquid-cooled V8 engine of only 90 hp output.

Wright-Hisso H

Wright-Hisso I

Wright-Hisso T