Hispano-Suiza 8

Hispano-Suiza 8
Preserved "direct-drive" Hispano-Suiza 8
Type V8 piston engine
Manufacturer Hispano-Suiza
First run 1914
Number built 49,800
Variants Wolseley Viper

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.[1] 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.

Design and development

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.[2] 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,[3] Clerget 9B rotary 130 hp,173 kg.[4]) 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 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[5]

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(engine manufacturer) 8(no of cylinders) A(engine series) b(variant), thus Hispano-Suiza 8Ab.

8 (HS-31)
100 kW (140 hp), initial production and test engines, with few applications, including early Nieuport 14s.
8Aa (HS-31)
110 kW (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 (HS-34)
130 kW (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 mm × 130 mm (4.7 in × 5.1 in) bore x stroke, 160 kW (210 hp) for take-off.[6]
Hispano-Suiza 8Be
8B (HS-35)
150 kW (200 hp), compression ratio 5.3:1, geared at 0.75:1. The HS-36 was the 8B with a Lewis gun firing through the propeller boss.
8B twin (HS-39)
Coupled 8B engines
8Ba
150 kW (200 hp) at 2,300 rpm, low compression ratio of 4.7:1, spur geared at 0.585:1.
8Bb
150 kW (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 175 kW (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.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
160 kW (220 hp), compression ratio of 5.3:1, reduction gear 0.75:1.
8Bd
160 kW (220 hp), compression ratio of 5.3:1, reduction gear 0.75:1.
8Bda
8Be
160 kW (220 hp), compression ratio of 5.3:1, reduction gear 0.75:1.
8BeC (HS-38)
The 8Be fitted with the 37 mm (1.457 in) 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 160 kW (220 hp) 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.[7]

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 160 kW (220 hp) 8s were given the company designation HS-38

Hispano Suiza 8Ca
Hispano Suiza 8Ca
HS-40
(8E ?)
HS-41
(8A ?)
8F (HS-42)
220 kW (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 (1,128.94 cu in). Despite the increased weight of 564 lb (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
220 kW (300 hp), aka HS Type 42, compression ratio of 5.3:1, direct drive.
8Fd
8Fe (HS-42VS)
(1926) 140 mm × 150 mm (5.5 in × 5.9 in) bore x stroke, 260 kW (350 hp) for take-off.[6]
Wolseley W.4A Python I
110 kW (150 hp), compression ratio of 4.7:1. License production of the 8Aa at Wolseley Motors Ltd.
Wolseley W.4A Python II
130 kW (180 hp), compression ratio of 5.3 :1.
Wolseley W.4A Viper
150 kW (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
160 kW (210 hp) at 2,000 rpm.[8]
Wolseley W.4B Adder I
150 kW (200 hp), compression ratio of 4.7 :1, reduction spur gear to 0.593:1.
Wolseley W.4B Adder II
150 kW (200 hp), compression ratio of 4.7 :1, reduction spur gear to 0.593:1. With stronger crankshaft webs.
Wolseley W.4B Adder III
150 kW (200 hp), compression ratio of 4.7 :1, reduction spur gear to 0.593:1. With balanced crankshafts.
Wright-Hisso A
130 kW (180 hp).
Wright-Hisso E
110 kW (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 67 kW (90 hp). output.
Wright-Hisso E-2
110 kW (150 hp) at 1,800 rpm.
Wright-Hisso E-3
Wright-Hisso E-4
160 kW (215 hp) at 2,000 rpm..
Wright-Hisso H
220 kW (300 hp)
Wright-Hisso H-3
220 kW (300 hp)
Wright-Hisso I
110 kW (150 hp)
M-6
A 220 kW (300 hp) Soviet Union produced copy of the 8Fb
Wright-Hisso V-720

Applications

Wright-Hispano E

Mitsubishi "Hi"shiki

200 HP (8B)
300 HP (8F)

Comparative table
Model 8A 8Aa 8Ab 8B 8F
Bore (mm)120140
Stroke (mm)130150
Displacement (l)11.7611.7618.47
Compression ratio4.75.3
Length (m)1.191.251.311.361.32
Width (m)0.810.830.850.860.89
Height (m)0.770.810.870.900.88
Weight(kg)195215230236256
Power output (hp)140150180200/235300
at (rpm)19002000210023002100

Specifications (Hispano-Suiza 8a)

General characteristics

Components

Performance

See also

Related development
Comparable engines
Related lists

References

  1. ↑ Browne, T.C. "Retrospect: 1924 Hispano-Suiza H6c Speedster", Motor Trend, 4/84, p.118.
  2. ↑ One prototype of this aircraft engine is preserved in Spanish museum "Museo de Aeronáutica y Astronáutica" in Madrid.
  3. ↑ Wikipedia article on BR2
  4. ↑ Wikipedia article on Clerget 9b
  5. ↑ Lumsden, Alec (2003). British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing. ISBN 1-85310-294-6.
  6. 1 2 Moteurs d'Aviation Hispano-Suiza (PDF) (in French). Boix-Colombes: Société Française Hispano-Suiza. 1932.
  7. ↑ "V-8, Hispano-Suiza Model 8 Ca". Retrieved 24 October 2010.
  8. ↑ http://www.flightglobal.com/pdfarchive/view/1919/1919%20-%200199.html Flight February 13, 1919 p 199

External links

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