Hispano-Suiza 8


The Hispano-Suiza 8 was a water-cooled V8 SOHC aero engine introduced by Hispano-Suiza in 1914, and was the most commonly used liquid-cooled engine in the aircraft of the Entente Powers during the First World War. The original Hispano-Suiza 8A was rated at and the later, larger displacement Hispano-Suiza 8F reached.
Hispano-Suiza 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 12Y which was in service during the Second World War.

Design and development

Origins

At the beginning of World War I, 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, 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 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 crankshaft was machined from a solid piece of steel. The cylinder blocks were cast aluminium and of monobloc type that is, in one piece with the SOHC cylinder heads. The inlet and exhaust ports were cast into the blocks, the valve seats were in the top face of the steel cylinder liners, which were screwed into the blocks. Using a rotating bevel gear-driven tower shaft 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.
Engine reliability and power to weight ratios were major problems in early aviation. The engine and its accessories weighed , making it 40% lighter than a rotary engine of equivalent power. This empty weight does not include the radiator and coolant fluid. Generally, air-cooled engines are lighter than their equivalent horsepower water-cooled counterparts. For example, the Bentley BR.2 rotary put out and weighed, Clerget 9B rotary,. The new engine was presented to the French 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 into military service. However, because of lobbying by French engine manufacturers, the Spanish-made engine was ordered to undergo a bench test that no French-made engine had yet passed: a 50-hour run at full speed. The HS-31 was therefore sent back to Chalais-Meudon on July 21, 1915, and tested for 50 hours, succeeding against all expectations. The design also promised far more development-potential than rotary engines. This was despite being the most common type, then in use, for most aircraft. Also, rotary engines were getting close to the limits of their development at this time. 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.
French officials ordered production of the 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 Louis Béchereau-designed SPAD VII was the result of this requirement and allowed the Allies to regain air superiority over the Germans.

Variants

Some data from: British Piston Engines and their Aircraft
Note: Hispano-Suiza company type numbers were prefixed by HS- or written in full as Hispano-Suiza Type 31, but military designations used the conventional system of Hispano-Suiza 8 A b r, thus Hispano-Suiza 8Abr.
;8 :, initial production and test engines, with few applications, including early Nieuport 14s.
;8Aa
;8Ab
;8Ac
;8Ad
;8B
;8B twin :Coupled 8B engines
;8Ba
;8Bb
The 8B series was used to power the earliest versions of the S.E.5a, all examples of the 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.
;8Bc:, compression ratio of 5.3:1, reduction gear 0.75:1.
;8Bd:, compression ratio of 5.3:1, reduction gear 0.75:1.
;8Be:, compression ratio of 5.3:1, reduction gear 0.75:1.
;8BeC : The 8Be fitted with the SAMC Model 37 cannon, or a similar weapon, firing through the propeller boss. A reduction gear equipped power-plant with a resultant clockwise rotation propeller like the 8B, produced at 2,100 rpm. Two known weapons fitted were the SAMC with a rifled barrel and a smooth-bore cannon firing canister ammunition. The moteur-canon could fire a single shot at a time through the hollow drive shaft without propeller interference. This cannon mount required an "elevated" intake manifold design, bringing the intake "runners" straight off the inner surfaces of the cylinder banks to the updraft carburetor's plenum chamber. The engine was used on the SPAD S.XII.
Note: The designations 8C, 8Ca, and 8Cb are probably contractions of the real STAe designation which would be similar to 8BeC or 8BeCa. Cannon-equipped 8s were given the company designation HS-38
;Hispano-Suiza Type 40:
;Hispano-Suiza Type 41:
;8F
;8Fa
;8Fb
;8Fd Special
;8Fe
;Wolseley W.4A Python I
;Wolseley W.4A Python II
;Wolseley W.4A Viper
;Wolseley W.4A Viper II
;Wolseley W.4B Adder I
;Wolseley W.4B Adder II
;Wolseley W.4B Adder III
;Wright-Hisso A:
;Wright-Hisso B: 4-cyl in-line water-cooled
;Wright-Hisso C: geared A
;Wright-Hisso D: geared A with cannon
;Wright-Hisso E:
;Wright-Hisso F:
;Wright-Hisso H:
;Wright-Hisso H-2: improved 'H'
;Wright-Hisso I:
;Wright-Hisso K: H with 37mm Baldwin cannon
;Wright-Hisso K-2:
;Wright-Hisso M: experimental 300hp
;Wright-Hisso T:
;Wright-Hisso 180hp V-8: direct drive
;Wright-Hisso 220hp V-8: geared drive
;Wright-Hisso 300hp V-8: geared drive
;M-6: A Soviet Union produced copy of the 8Fb
;Wright-Hisso V-720

Applications

;200 HP
;300 HP

Engines on display