Editing Avro Shackleton (section)

==Variants==

===Avro 696 Shackleton prototypes===
Three prototype Type 696s were ordered in May 1947 to meet specification R 5/46:
;VW126
:The first prototype which initially flew on 9 March 1949.<ref name="aero01">{{cite journal|journal=Aeromilitaria|title=Avro Shackleton MR.Mk1, MR.Mk.1A and T.Mk.4 in Royal Air Force Service|year=1975|issue=1|publisher=[[Air-Britain]]}}</ref>
;VW131
:First flown on 2 September 1949.
;VW135
:First flown on 29 March 1950.

===Avro 696 Shackleton Mk.1===
;Shackleton MR.Mk.1
:The first production model for the RAF with a dorsal twin 20 mm cannon turret, 29-built.<ref name="aero01" /> First production aircraft flew on 28 March 1950 and the variant entered service with 120 Squadron at RAF Kinloss in March 1951.<ref name="aero01" />
;Shackleton MR.Mk.1A
:Variant powered by four Griffon 57A V12 piston engines, in service from April 1951, 47-built and all surviving MR.1s converted.<ref name="aero01" />
;Shackleton T.4
:Navigation trainer conversion from MR 1As between 1956 and 1961, mid-upper turret and crew rest area removed, additional radar and radio positions for trainees added, 17 conversions.<ref name="aero01" />

===Avro 696 Shackleton Mk.2===
The Mark 2 had a longer nose and the radome was moved to the ventral position. A lookout position was added to the tail, two more 20&nbsp;mm cannons were added in the nose, and twin retractable tailwheels were fitted. One aircraft, WB833, originally ordered as an MR.1 was built as an MR.2 prototype and first flew on 17 June 1952.<ref name="aero76">{{cite journal|journal=Aeromilitaria|title=Avro Shackleton MR.2 in Royal Air Force Service|year=1976|issue=4/76|publisher=[[Air-Britain]]}}</ref> The last ten MR.1s on the production line were completed as MR.2s and orders for 80 new-build aircraft were placed; the last 21 were completed as MR.3s, the total number of MR.2s built being 69.<ref name="aero75" /> The first aircraft entered service with [[No. 42 Squadron RAF|42 Squadron]] at [[RAF St Eval]] in January 1953.<ref name="aero75" />

Mk.2s were later modified in parallel with phased modifications to the Mk.3:<ref name="howard">Howard (1972)</ref>

MR.Mk.2 Phase 1 or MR.Mk.2C: as per Mk.3 Phase 1.<ref name="aero76" /> Also received the sonics plotting table from the Mk.3.

MR.Mk.2 Phase 2: as per Mk.3 Phase 2.<ref name="aero76" />

MR.Mk.2 Phase 3: as per Mk.3 Phase 3, except that the Viper engines were not fitted.<ref name="aero76" />

'''Shackleton T.2'''
Ten MR 2 Phase 3 aircraft were modified in 1967 as T.2s at Langar to replace the T.4s with the Maritime Operational Training Units as radar trainers, with master and slave radar positions for training installed.<ref name="aero76" />

'''Shackleton AEW.2'''
In 1971 twelve MR.2s were converted at Woodford and Bitteswell as Airborne Early Warning aircraft, being fitted with  [[AN/APS-20]] radar in order to perform the [[Airborne early warning and control|Airborne Early Warning]] role. The first AEW.2 flew on 30 September 1971 and the type entered service with [[No. 8 Squadron RAF|8 Squadron]] on 1 January 1972.<ref name="aero76" /> The AEW.2 was retired on 1 July 1991.{{sfn|March|1992|p=75}}

===Avro 716 Shackleton Mk.3===
[[File:Shackleton-WR974-295.jpg|thumb|MR3 on display in 2008]]
Shackleton MR.Mk.3
Tailwheel undercarriage replaced by a tricycle undercarriage, nose entrance hatch added and wingtip tanks fitted to increase fuel capacity.<ref name="aero75" /> To increase crew comfort the inside was sound proofed, better crew seats were fitted and the tactical team positions rearranged.<ref name="aero75" />  To make room for some of the internal rearrangement the dorsal turret was deleted.<ref name="aero75" /> The first MR.3 flew on 2 September 1955; the aircraft had problems with stalling characteristics and crashed on 7 December 1956.<ref name="aero75" /> The variant entered service with 220 Squadron at RAF St Eval in August 1957.<ref name="aero75" /> The RAF ordered 52 aircraft but later, following the 1956 Defence Review, the order was reduced to 33 aircraft.<ref name="aero75" /> An additional aircraft was also built to replace the aircraft lost during stalling trials.<ref name="aero75" /> An additional eight aircraft were exported to [[South Africa]].

The aircraft underwent several phased modifications:

The Phase 1 update introduced changes mainly to the internal equipment.<ref name="aero75">{{cite journal|journal=Aeromilitaria|title=Avro Shackleton MR.3 in Royal Air Force Service|year=1975|issue=2/75|publisher=[[Air-Britain]]}}</ref>

The {{anchor|Shackleton MR.Mk.3 Phase 2}} Phase 2 update introduced [[electronic countermeasure|ECM]] equipment, the distinctive [[Orange Harvest]] 'spark plug' [[Electronic warfare support measures|ESM]] aerial and an improved High Frequency radio.<ref name="aero75" />
[[File:Avro Shackleton XF708 left wing engines from rear 1992.jpg|thumb|right|MR.3 XF708 left wing showing outer engine nacelle (left) with propellers at front and Viper turbojet exhaust at rear. Compare with inner nacelle.]]

The Phase 3 update introduced two [[Armstrong Siddeley Viper]] turbojet engines at the rear of the outboard engine nacelles to be used for assisted takeoff. The wing main spars had to be strengthened due to the additional engines. A new navigation system was also fitted and there were some modification to the internal arrangement, including a shorter crew rest area to give more room for the tactical positions.<ref name="aero75" /><ref name="jeff 103">Jefford et al. 2005, p. 103.</ref>

===Projected designs===
;Avro 717 and 719 Shackleton MR.Mk.4
:Project for a re-engined MR.Mk.1 using [[Napier Nomad]] engines. Two Nomads were installed in the outer nacelles of a Shackleton prototype to create the only Avro 717 example, but the program was cancelled before the aircraft could be flown. The Avro 719 would have replaced all four Griffons with Nomads.<ref name="howard" />

;Shackleton MR.Mk.5
:MR.Mk.5 was a suggested designation for a Nomad-powered variant of the Mk.2.<ref name="howard" />