The Armstrong Siddeley Viper is a British turbojet engine developed and produced by

Armstrong Siddeley Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines. The company was created following ...

and then by its successor companies

Bristol Siddeley Bristol Siddeley Engines Ltd (BSEL) was a British aero engine manufacturer. The company was formed in 1959 by a merger of Bristol Aero-Engines Limited and Armstrong Siddeley Motors Limited. In 1961 the company was expanded by the purchase of t ...

and Rolls-Royce Limited. It entered service in 1953 and remained in use with the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

, powering its Dominie T1 navigation training aircraft until January 2011.

Design and development

The design originally featured a seven-stage compressor based on their

Adder Adder may refer to: * AA-12 Adder, a Russian air-to-air missile * Adder (electronics), an electronic circuit designed to do addition * Adder Technology, a manufacturing company * Armstrong Siddeley Adder, a late 1940s British turbojet engine * ''B ...

engine — the Viper is in effect a large-scale Adder. Like the similar

J85 J85 may refer to: *General Electric J85, a small single-shaft turbojet engine *HMS Seagull (J85), a Halcyon class minesweeper of Royal Navy *J85, the Johnson solid notation for a snub square antiprism In geometry, the snub square antiprism is o ...

built in United States, the Viper was originally developed as an expendable engine for production versions of the Jindivik target drone. Like the J85, the limited-life components and total-loss oil systems were replaced with standard systems for use in crewed aircraft. Because it was initially developed as an expendable engine, the Viper was subject to many recurring maintenance issues. This led to the development of the first

Power by the Hour Aircraft maintenance is the performance of tasks required to ensure the continuing airworthiness of an aircraft or aircraft part, including overhaul, inspection, replacement, defect rectification, and the embodiment of modifications, compliance w ...

program in which operators would pay a fixed hourly rate to Bristol Siddeley for the continual maintenance of the engines. In the 1970s, Turbomecanica

Bucharest Bucharest ( , ; ro, București ) is the capital and largest city of Romania, as well as its cultural, industrial, and financial centre. It is located in the southeast of the country, on the banks of the Dâmbovița River, less than north ...

and Orao

Sarajevo Sarajevo ( ; cyrl, Сарајево, ; ''see names in other languages'') is the capital and largest city of Bosnia and Herzegovina, with a population of 275,524 in its administrative limits. The Sarajevo metropolitan area including Sarajev ...

acquired the license for the Viper engine, which propelled various Romanian and Yugoslav built aircraft.INCAS - IAR 93 and SOKO /VTJ - J - ORAO Specifications
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Variants

''Data from:''Jane's All the World's Aircraft 1955-56, Jane's all the World's Aircraft 1959-60, Jane's All the World's Aircraft 1962-63 ;ASV.1:Short life design study; . ;ASV.2:Developed short life version, first run in April 1951; . ;ASV.3: (Mk.100) Short life for missile/target applications, flight-tested in the tail of an

Avro Lancaster The Avro Lancaster is a British World War II, Second World War heavy bomber. It was designed and manufactured by Avro as a contemporary of the Handley Page Halifax, both bombers having been developed to the same specification, as well as the S ...

November 1952; . ;ASV.4:Short life for missile/target applications first run in 1952, . ;ASV.5:(Mk. 101) Extended life version for crewed aircraft. ;ASV.6:Short life for missile/target applications; . ;ASV.7: ;ASV.7/R: ASV.7 with re-heat;. ;ASV.8: (became Viper 8 and Mk.102); Long-life version rated at for Jet Provost T Mk.3. ;ASV.9: (became Viper 9 and Mk.103) Similar to ASV.8 with improved turbine materials; . ;ASV.10:Long-life version with re-designed Sapphire-style compressor first run in January 1956; . ;ASV.11: (became Viper 11 and Mk.200) ASV.10 with increased mass-flow; . ;ASV.12: (became Viper 12) up-rated ASV.11 with higher JPT and rated at ;Viper 8: (Mk.102 / Mk.104): Engines for the

Hunting-Percival Jet Provost TMk.3 The BAC Jet Provost is a British jet trainer aircraft that was in use with the Royal Air Force (RAF) from 1955 to 1993. It was originally developed by Hunting Percival from the earlier piston engine-powered Percival Provost basic trainer, an ...

(Mk.102) and

GAF Jindivik Mk.102B The GAF Jindivik is a radio-controlled target drone produced by the Australian Government Aircraft Factories (GAF). The name is from an Aboriginal Australian word meaning "the hunted one". Two manually-controlled prototypes, were built as the GAF ...

target drone (Mk.104). ;Viper 9: (Mk.103): Powered the

Bell X-14 The Bell X-14 (Bell Type 68) is an experimental VTOL aircraft flown in the United States in the 1950s. The main objective of the project was to demonstrate vectored thrust horizontal and vertical takeoff, hover, transition to forward flight, ...

and Handley Page HP 115 among others. ;Viper 11: (Mk.200): Powered the

Hunting-Percival Jet Provost TMk.4 The BAC Jet Provost is a British jet trainer aircraft that was in use with the Royal Air Force (RAF) from 1955 to 1993. It was originally developed by Hunting Percival from the earlier piston engine-powered Percival Provost basic trainer, a ...

(Mk202) and

GAF Jindivik Mk.3 The GAF Jindivik is a radio-controlled target drone produced by the Australian Government Aircraft Factories (GAF). The name is from an Aboriginal Australian word meaning "the hunted one". Two manually-controlled prototypes, were built as the G ...

among others. ;Viper 12: see ASV.12 above ;Viper 20: (Mk.500 series): Powered the Hawker Siddeley HS.125 and Piaggio-Douglas PD.808 among others. ;Viper 22: Built under licence by

Piaggio Piaggio & C. SpA (Piaggio ) is an Italian motor vehicle manufacturer, which produces a range of two-wheeled motor vehicles and compact commercial vehicles under seven brands: Piaggio, Vespa, Gilera, Aprilia, Moto Guzzi, Derbi, and Scarabeo. ...

for the Aermacchi MB.326 ;Mk.100: see ASV.3 above ;Mk.101: see ASV.5 above ;Mk.102: see ASV.8 above ;Mk.103: see ASV.9 and Viper 9 above ;Mk.104: see ASV.12 above ;Mk.200: ;Mk.201: ;Mk.202: ;Mk.204: ;Mk.301: ;Mk.521: ;Mk.522: ;Mk.525: ;Mk.601: ;Mk.632: Built under licence by Turbomecanica and Orao, as the non-afterburning engine for the IAR-93 Vultur A/MB versions,

Soko J-22 Orao The Soko J-22 Orao ( sr-cyr, text=Oрао, translation=eagle) is a Yugoslav twin-engined, subsonic ground-attack and aerial reconnaissance aircraft. It was developed and built in collaboration by SOKO in Yugoslavia and by Avioane Craiova in ...

1 version, IAR-99 Standard/Șoim versions, and

Soko G-4 Super Galeb The Soko G-4 Super Galeb ( en, Super Seagull), also referred to as N-62, is a Yugoslav single-engine, advanced jet trainer and light ground-attack aircraft designed by the Aeronautical Technical Institute at Žarkovo and manufactured by the S ...

. ;Mk.633: Built under licence by Turbomecanica and Orao, as the afterburning engine for the IAR-93 Vultur B version, and

2 version. ;M.D.30 Viper:Engines licence-built and developed by

Dassault Aviation Dassault Aviation SA () is a French manufacturer of military aircraft and business jets. It was founded in 1929 by Marcel Bloch as Société des Avions Marcel Bloch or "MB". After World War II, Marcel Bloch changed his name to Marcel D ...

;M.D.30R Viper: with afterburner.

Applications

Specifications (Viper ASV.12)

References

Notes

Bibliography

* * Gunston, Bill. ''World Encyclopedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. * Smith, Tom. "Expendable to Indispensable: The Story of a Classic Turbojet - The Viper". ''Air Enthusiast'', No. 55, Autumn 1994, pp. 37–55.

External links

Rolls-Royce - Viper
{{RR aeroengines

Viper The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs th ...

1950s turbojet engines