Armstrong Siddeley Viper

The Armstrong Siddeley Viper is a British turbojet engine developed and produced by Armstrong Siddeley and then by its successor companies Bristol Siddeley and Rolls-Royce Limited. It entered service in 1953 and remained in use with the Royal Air Force, 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 engine &mdash; the Viper is in effect a large-scale Adder.

Like the similar J85 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 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 and Orao Sarajevo acquired the license for the Viper engine, which propelled various Romanian and Yugoslav built aircraft.

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; 1145 lbf.
 * ASV.2:Developed short life version, first run in April 1951; 1145 lbf.
 * ASV.3: (Mk.100) Short life for missile/target applications, flight-tested in the tail of an Avro Lancaster November 1952; 1640 lbf.
 * ASV.4:Short life for missile/target applications first run in 1952, 1750 lbf.
 * ASV.5:(Mk. 101) Extended life version for crewed aircraft.
 * ASV.6:Short life for missile/target applications; 1900 lbf.
 * ASV.7:
 * ASV.7/R: ASV.7 with re-heat; 2470 lbf.
 * ASV.8: (became Viper 8 and Mk.102); Long-life version rated at 1750 lbf for Jet Provost T Mk.3.
 * ASV.9: (became Viper 9 and Mk.103) Similar to ASV.8 with improved turbine materials; 2000 lbf.
 * ASV.10:Long-life version with re-designed Sapphire-style compressor first run in January 1956; 1900 lbf.
 * ASV.11: (became Viper 11 and Mk.200) ASV.10 with increased mass-flow; 2500 lbf.
 * ASV.12: (became Viper 12) up-rated ASV.11 with higher JPT and rated at 2700 lbf
 * Viper 8: (Mk.102 / Mk.104): Engines for the Hunting-Percival Jet Provost TMk.3 (Mk.102) and GAF Jindivik Mk.102B target drone (Mk.104).
 * Viper 9: (Mk.103): Powered the Bell X-14 and Handley Page HP 115 among others.
 * Viper 11: (Mk.200): Powered the Hunting-Percival Jet Provost TMk.4(Mk202) and GAF Jindivik Mk.3 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 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: see Viper 11 above
 * Mk.201:
 * Mk.202: see Viper 11 above
 * 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 1 version, IAR-99 Standard/Șoim versions, and Soko G-4 Super Galeb.
 * Mk.633: Built under licence by Turbomecanica and Orao, as the afterburning engine for the IAR-93 Vultur B version, and Soko J-22 Orao 2 version.
 * M.D.30 Viper:Engines licence-built and developed by Dassault Aviation
 * M.D.30R Viper:2200 lbf with afterburner.

Applications
• Aermacchi MB-339

• Aermacchi MB-326

• Aero L-29 Delfin (prototype only)

• Atlas Aircraft Impala

• Avro Shackleton

• BAC Jet Provost

• BAC Strikemaster

• Bell X-14

• Blue Origin Charon

• Dassault M.D.550 Mystere-Delta

• Embraer AT-26 Xavante

• Folland Midge

• GAF Jindivik

• Hawker Siddeley Dominie

• Handley Page HP.115

• IAR 99

• Piaggio PD.808

• Saunders-Roe SR.53

• Soko J-22 Orao/IAR-93 Vultur

• Soko G-2 Galeb

• Soko G-4 Super Galeb