Wolseley Viper

Viper
Viper
	Rear view of preserved Wolseley Viper
Type	Piston inline aero-engine
Manufacturer	Wolseley Motors
First run	1918
Major applications	Royal Aircraft Factory S.E.5

The Wolseley Viper is a British-built, high-compression derivative of the Hispano Suiza HS-8 liquid-cooled V8 engine, built under licence by Wolseley Motors during World War I.

It powered later models of the S.E.5a, SPAD VII and other British or British-built aircraft designed for the Hispano-Suiza.

Variants

Wolseley W.4A Python I (1917)
150 hp (110 kW) – licence produced version of the Hispano-Suiza 8Aa with minor structural changes and the weight increased to 455 lb (206 kg), retained the original's low compression 1.8 in (45 mm) pistons and compression ratio of 4.7:1. Only 100 built.
Wolseley W.4A Python II
180 hp (130 kW) – high compression version of the Python I with high compression 2 in (50 mm) pistons and compression ratio increased to 5.3:1.
Wolseley W.4A* Viper (1918)
200 hp (150 kW) – broadly the equivalent of the Hispano-Suiza 8Ab, compression ratio of 5.3:1 (19 early production engines had a higher compression ratio of 5.6:1), with 200 hp English Hispano propeller hubs.
Wolseley W.4B Adder I (1918)
200 hp (150 kW) – modified version of the Hispano-Suiza 8B.
Wolseley W.4B* Adder II
200 hp (150 kW) – modified and improved version of the Adder I.
Wolseley W.4B* Adder III
200 hp (150 kW) – modified and improved version of the Adder II with balanced crankshaft.

A preserved Wolseley Viper is on public display at the Science Museum, London.
A preserved Wolseley Viper is on public display at the Museo Nacional de Aeronáutica de Argentina

Data from Gunston and Lumsden

1 2 Gunston (1986), p. 76.
1 2 Lumsden (1994), pp. 156 & 232.
1 2 3 4 5 Lumsden (1994), p. 232.
↑ Gunston (1986), p. 171.
↑ The Shuttleworth Collection - SE5a Archived 23 July 2019 at the Wayback Machine www.shuttleworth.org Retrieved: 09 March 2017.

Gunston, Bill (1986). World Encyclopaedia of Aero Engines. Wellingborough: Patrick Stephens Ltd. ISBN 0-85059-717-X.
Lumsden, Alec (1994). British Piston Engines and Their Aircraft. Shrewsbury: Airlife Publishing Ltd. ISBN 1-85310-294-6.

v t e Wolseley aero engines
V8 engines (1910–1918)	60 hp 80 hp 160 hp Adder Python Viper
Radial engines (1931–1935)	AR.7 (Aquarius) AR.9 (Aries, Leo, Libra, Scorpio)