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[[Image:31 Shackleton mail drop Aug1970.jpg|300px|thumb|Avro Shackleton]]
The '''Shackleton''' was a [[Royal Air Force]] long-range [[patrol bomber]] developed from the [[Avro Lincoln]] bomber with a new fuselage. It was originally used primarily in the [[anti-submarine warfare]] (ASW) and [[maritime patrol aircraft]] (MPA) roles, and was later adapted for [[AEW|airborne early warning]] (AEW), [[search and rescue]] (SAR) and other roles from 1951 until 1990. It also served in the [[South African Air Force]] from 1957 to 1984. The design is named after the polar explorer Sir [[Ernest Shackleton]].

==History==
The aircraft was designed by [[Roy Chadwick]] as the [[Avro]] '''Type 696'''. It was clearly based on the successful wartime [[Avro Lancaster]] bomber, one of Chadwick's designs and the Lancaster derivative the [[Avro Lincoln]], which was the then current ASW aircraft. The design took the Lincoln's wings and landing gear and mated them with a new fuselage. The engines were [[Rolls-Royce Griffon]]s with 13 feet (4 m) [[contra-rotating]] [[propellor]]s, creating a distinctive engine noise and adding high-tone deafness to the hazards of the pilots. The first test flight was in March 1949 and front-line aircraft were delivered to [[Coastal Command]] in April 1951 and had their operational debut during the [[Suez Crisis]]. In the ASW role, the Shackleton carried both types of [[sonobuoy]], [[ESM]], a [[diesel]] fume detection system and for a short time an unreliable [[magnetic anomaly detector]] (MAD) sytem. Weapons were nine bombs, or three [[torpedo]]es or [[depth-charge]]s, and 20 mm cannon.

The '''MR.2''' was improved with feedback from operations and is considered by aficionados to be the definitive type. The [[radome]] was moved from the nose to a [[ventral]] position, to improve all-round coverage and minimise the risk of bird-strikes. Both the nose and tail sections were lengthened, the tail planes were redesigned and the weak undercarriage was strengthened.

The '''MR.3''' was another redesign in response to crew complaints. A new [[tricycle undercarriage]] was introduced, the fuselage was increased in all main dimensions and had new wings with better ailerons and tip tanks. As a sop to the crews on fifteen hour flights the sound deadening was improved and a proper [[galley]] and sleeping space were included. Total take-off weight had risen by over 30,000 lb (13,600 kg) (Ph. III) and assistance from [[Armstrong-Siddeley Viper|Rolls-Royce Viper]] Mk.203 [[turbojet]]s was needed on take-off ([[JATO]]). This extra strain told on the airframe and the flight life of the Mk. IIIs was sufficiently reduced that they were outlived by the Mk. IIs.

All marks suffered from using the Griffon engines — thirsty for fuel and oil, noisy and temperamental with high-maintenance needs. In 1961 MR.2's engines needed top overhauls every 400 hours and went through a spate of ejecting spark plugs from their cylinderheads. It was not unusual to see an engine changed every day in a unit of 6 aircraft. They were constantly on the cusp of being replaced, but even the potentially beneficial [[Napier Nomad]] re-engine didn't quite happen.

The need to replace the Shackleton was first raised in the early 1960s. The arrival of the [[Hawker-Siddeley Nimrod]] in 1969 was the end for the Shackleton in most roles but it continued as the main SAR aircraft until 1972. The intention to retire the aircraft was then thwarted by the need for AEW coverage in the North Sea and northern Atlantic following the retirement of the [[Fairey Gannet]]. With a new design not due until the late 1970s the existing AN/APS-20 radar was installed in Mk. IIs as an interim measure, the '''AEW.2''', from 1972. The disastrous Nimrod AEW replacement program dragged on and on and the eventual successor to the Shackleton did not arrive until the RAF finally gave in and purchased the [[E-3 Sentry]] in 1991.

A total of 185 Shackletons were built from 1951 to 1958: around twelve are still believed to be intact, with one still flying.

==Variants==
* '''Shackleton GR.1''' : The Shackleton GR.1 was the first production model for the RAF. It was later redesignated '''Shackleton MR.1'''.
* '''Shackleton MR.1A''' : Fitted with four Griffon 57A V12 piston engines, plus a chin mount radome. In service from April 1951.
* '''Shackleton MR.2''' : Longer nose. Radome moved to the ventral position.
* '''Shackleton MR.2C''' 
* '''Shackleton MR.3''' : Maritime reconnaissance, anti-shipping aircraft. The tail wheel was replaced by a tricycle undercarriage configuration. Fitted with wingtip tanks, plus two Viper turbojet engines for assisted take off. Eight exported to [[South Africa]].
* '''Shackleton MR.4''' Unbuilt project, none built.
* '''Shackleton AEW.2''' : Airborne early warning aircraft. MR.2s converted to take ex-[[Fairey Gannet]] airborne early warning radar.
* '''Shackleton T.4''' : Converted for use as a navigation trainer.

==Operators==
* South Africa, United Kingdom.


===External links===
*[http://www.aircraft.co.za/Encyclopedia/A/98.php Aircraft.co.za - The Complete Aviation Reference]
*[http://users.bigpond.net.au/Shackleton/ Avro Shackleton Site]
*[http://website.lineone.net/~avro.shackleton/ David Gubbins Website with airframe histories]

[[Category:Military Aircraft]]


== Copyright ==
"Original data received from Wikipedia on April 11, 2006. Credit given to original authors can be seen [http://en.wikipedia.org/w/index.php?title=Avro_Shackleton&action=history Here]."