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Hispano-Suiza 8A
Wolseley W.4B Adder
Wolseley W.4A Python Wolsely W.4A Viper
Wright-Hisso A Wright-Hisso H
Mitsubishi "Hi" Shiki
The Hispano-Suiza 8 was a water-cooled V8 SOHC aero engine introduced by Hispano-Suiza in 1914 and was the most commonly used engine in the aircraft of the Entente Powers during the First World War. The original Hispano-Suiza 8A was rated at 140 hp (102 kW) and the later Hispano-Suiza 8F reached 300 hp (220 kW).
HS-8 engines and variants produced by Hispano-Suiza and other companies under licence were built in twenty-one factories in Spain, France, Britain, Italy, and the U.S. Derivatives of the engine were also used abroad to power numerous aircraft types and the engine can be considered as the ancestor of another successful engine by the same designer, the Hispano-Suiza HS-12Y (and Soviet Klimov V12 derivative aero-engines) which served in World War II.
When World War I began, the production lines of the Barcelona based Hispano-Suiza automobile and engine company were switched to the production of war materiel. Chief engineer Marc Birkigt led work on an aircraft engine based on his successful V8 automobile engine. The resulting engine, called the Hispano-Suiza 8A (or HS-8A), made its first appearance in February 1915.
The first 8A kept the standard configuration of Birkigt's existing design: eight cylinders in 90° Vee configuration, a displacement of 11.76 litres (717.8 cu in) and a power output of 140 hp at 1,900 rpm. In spite of the similarities with the original design, the engine had been substantially refined. The crankcase was machined from a solid piece of steel. The cylinders were cast aluminium with steel liners. The SOHC cylinder heads were also made of aluminium, using a rotary driveshaft (tower gear) coming up from the crankcase along the rear end of each cylinder bank, with the final drive for each cylinder bank's camshaft accommodated within a semicircular bulge at the rear end of each valve cover. Aluminium parts were coated in vitreous enamel to reduce leakage. All parts subject to wear, and those critical for engine ignition were duplicated: spark plugs for dual ignition reliability, valve springs, magnetos, etc.
Although engine reliability was a great concern in these opening stages of aviation, the HS-8A also provided a good power-to-weight ratio and development potential. The engine and its accessories weighed 185 kg (408 lb), making it 40% heavier than a rotary engine of equivalent power. The design also promised far more development potential than rotary engines which, in spite of being the most common type then in use for aircraft, were getting close to the limits of their potential. Rotary engines of increased power generally had increased weight, which in turn increased the already serious gyroscopic torque generated by the engine's rotation. A further increase in torque was considered unacceptable, and the power-to-weight ratio of the new rotary engines under development did not appeal to aircraft designers.
The new engine was presented to the French Ministère de la Guerre (Ministry of War) in February 1915, and tested for 15 hours at full power. This was standard procedure for a new engine design to be admitted in military service. However, because of lobbying by French engine manufacturers, the HS-8A was ordered to undergo a bench test that no French-made engine had yet achieved successfully: a 50-hour run at full speed. The HS-8A was therefore sent back to Chalais-Meudon on July 21, 1915 and tested for 50 hours, succeeding against all expectations.
French officials ordered production of the HS-8A to be started as soon as possible and issued a requirement for a new single-seat high-performance fighter aircraft using the new engine. The SPAD VII was the result of this requirement and would allow the Allies to regain air superiority over the Germans.
Guynemer informed Bechereau in December 1916 that "the Halberstadt [while] not faster, climbs better, consequently it has the overall advantage". In the quest for more power, Marc Birkigt increased the compression ratio of the 8A engine from 4.7 to 5.3, which in turn raised its revolutions from 1500 to 1800 per minute. This resulted in a power output of 180hp, enabling a significant improvement in the SPAD VII's performance to be achieved. Apart from the extra power, the new Hispano-Suiza 8Ab proved extremely reliable.
 Hispano Suiza 8Ca
Approximately 49,800 were built.
The Wolseley Viper is a British-built, high-compression derivative of the Hispano Suiza HS-8 liquid-cooled V-8 engine, built under licence by Wolseley Motors during World War I and first run in 1918.
It powered later models of the S.E.5a, SPAD VII and other British or British-built aircraft designed for the Hispano-Suiza.
Wolsley Viper
Variants: 8A (HS-8A)
8Aa (HS-8Aa)
8Ab (HS-8Ab)
8Ac (HS-8Ac)
8B (HS-8B)
8Ba (HS-8Ba)
8Ba (HS-8Bb)
8Ba (HS-8Be)
 Hispano-Suiza 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 SA 18 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.  Hispano Suiza 8Ca
8F (HS-8F)
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
Wolseley W.4A Viper II
Wright-Hisso A
Wright-Hisso E
Wright-Hisso I Wright-Hisso T
Applications: Wright-Hispano E Mitsubishi "Hi" shiki 300 HP (8F)
Wolsely W.4
Hispano-Suiza 8a 8Aa 8Ab 8B 8F
Wolsely W.4A Viper
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