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 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.

Origins
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 crankshaft 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.

Engine reliability and power to weight ratios were major problems in early aviation. The engine and its accessories weighed 185 kg (408 lb), making it 40% lighter than a rotary engine of equivalent power. (Note: 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 BR2 rotary put out 230 hp and weighed 220 kg, Clerget 9B rotary 130 hp,173 kg. ) 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-8A 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 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.

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.

Variants
Some data from: British Piston Engines and their Aircraft

Note: Hispano-Suiza production engine designations were prefixed by HS-.
 * 8: 140 hp, initial production and test engines, with few applications, including the Airco DH.6.
 * 8Aa
 * 150 hp at 2000 rpm, entered production in July 1915. Early HS-8A engines were plagued with various problems which required further work and 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 licence, 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.


 * 8Ab
 * 180 hp at 2,100 rpm, increasing the compression ratio from 4.7 to 5.3, Birkigt was able to increase the power output . The 8Ab began replacing the 8Aa on SPAD VIIs in early 1917.


 * 8Ac


 * 8Ad
 * (1929) 120 x bore x stroke, 210 hp for take-off.


 * 8B
 * 200 hp, compression ratio 5.3:1, geared at 0.75:1


 * 8Ba
 * 200 hp at 2,300 rpm, low compression ratio of 4.7:1, spur geared at 0.585:1.


 * 8Bb
 * 200 hp, compression ratio of 4.8:1, reduction gear 0.75:1. 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 8B series 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 (viewed from in front, otherwise known as a left hand tractor) rotation propeller.


 * 8Bc: 220 hp, compression ratio of 5.3:1, reduction gear 0.75:1.


 * 8Bd: 220 hp, compression ratio of 5.3:1, reduction gear 0.75:1.
 * 8Bda


 * 8Be: 220 hp, compression ratio of 5.3:1, reduction gear 0.75:1.
 * 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. 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.


 * 8Cb:Generally similar to the 8Ca, for use on the SPAD XIII.


 * 8F
 * 300 hp at 2,100 rpm (eq. 750 lb·ft torque). The direct drive 8F was basically a bored out version of the 8B, intended for use in bombers, with a displacement of 18.5 l. Despite the increased weight of 256 kg, the 8F was also installed in fighters such as the Nieuport-Delage NiD 29 and Martinsyde Buzzard, and 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
 * generally similar to the 8F.


 * 8Fb
 * 300 hp, aka HS Type 42, compression ratio of 5.3:1, direct drive.


 * 8Fd
 * 8Fe
 * (1926) 140 x bore x stroke, 350 hp for take-off.
 * (1926) 140 x bore x stroke, 350 hp for take-off.


 * Wolseley W.4A Python I
 * 150 hp, compression ratio of 4.7:1. License production of the 8Aa at Wolseley Motors Ltd.


 * Wolseley W.4A Python II
 * 180 hp, compression ratio of 5.3 :1.


 * Wolseley W.4A Viper
 * 200 hp, compression ratio of 5.3 :1. Wolseley's engineers removed problems with the crankshaft and increased the compression ratio to give more power, with some early engines having a compression ratio of 5.6:1.


 * Wolseley W.4A Viper II
 * 210 hp at 2,000 rpm.


 * Wolseley W.4B Adder I
 * 200 hp, compression ratio of 4.7 :1, reduction spur gear to 0.593:1.


 * Wolseley W.4B Adder II
 * 200 hp, compression ratio of 4.7 :1, reduction spur gear to 0.593:1. With stronger crankshaft webs.


 * Wolseley W.4B Adder III
 * 200 hp, compression ratio of 4.7 :1, reduction spur gear to 0.593:1. With balanced crankshafts.


 * Wright-Hisso A
 * 180 hp.


 * Wright-Hisso E
 * 150 hp. The American Wright-Martin aviation firm licence-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 E-2
 * 150 hp at 1,800 rpm.


 * Wright-Hisso E-3


 * Wright-Hisso E-4
 * 215 hp at 2,000 rpm..


 * Wright-Hisso H
 * 300 hp


 * Wright-Hisso H-3
 * 300 hp


 * Wright-Hisso I
 * 150 hp

Applications

 * Austin-Ball A.F.B.1 (single prototype)
 * Avia BH-21 (rrom 1925)
 * Avia BH-22
 * Bartel BM-5
 * Bernard SIMB AB 10
 * Blanchard Brd.1
 * Caudron C.59
 * Caudron R.11
 * Curtiss JN-4H Jenny
 * FBA Type H
 * Fokker D.IX
 * Fokker D.X
 * Fokker D.XII
 * Fokker S.III
 * Gourdou-Leseurre GL.21
 * Hanriot HD.5
 * Hanriot HD.15
 * Hanriot HD.20
 * Letov Š-7
 * Letov Š-13
 * Letov Š-14
 * Martinsyde F.4 Buzzard
 * Nieuport 29 (8Fb)
 * S.E.5 and S.E.5a (8a and the Wolseley Viper derivative),
 * Sopwith Dolphin (8B)
 * Sopwith Cuckoo
 * SPAD S.VII (8a)
 * SPAD S.XI (8Be)
 * SPAD S.XII (8Cb), with 37 mm calibre moteur-canon mount through the hollow propshaft
 * SPAD S.XIII (8Be)
 * Standard J-1 training biplanes, especially on restored, airworthy examples
 * Waco DSO (8a)
 * Wibault 1 (single prototype)

Wright-Hispano E

 * Boeing NB-2
 * AT-3
 * Consolidated PT-1
 * Cox-Klemin TW-2
 * Dayton-Wright TW-3
 * Huff-Daland TW-5
 * Curtiss AT-4
 * Vought VE-7
 * Waco DSO

Mitsubishi "Hi"shiki

 * 200 HP (8B)
 * Yokosuka Ro-go Ko-gata
 * Hansa-Brandenburg W.29 (Japanese version)
 * 300 HP (8F)
 * Mitsubishi 1MF
 * Mitsubishi 2MR