Editing Avro Lancaster

{{Short description|World War II British heavy bomber aircraft}}
{{EngvarB|date=April 2017}}
{{use dmy dates|date=August 2019}}
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{{Infobox aircraft
 |name= Lancaster
 |image= File:Battle of Britain Memorial flight Avro Lancaster (cropped).jpg
 |long_caption= Lancaster B.I ''[[PA474]]''{{NoteTag|This aircraft carries the deepened bomb aimer blister (Mod. 780) and the later paddle-bladed propellers. Neither [[H2S radar|H2S]] blister nor exhaust shrouds are fitted.}} of the RAF Battle of Britain Memorial Flight in 460 Squadron (RAAF) colours
 |aircraft_type= [[Heavy bomber]]
 |national_origin= United Kingdom
 |manufacturer= [[Avro]]
 |builder= Avro and [[#Production|five others]] (in UK & Canada)
 |designer= [[Roy Chadwick]]
 |first_flight= 9 January 1941
 |introduction= February 1942
 |retired= April 1, 1964 [[Royal Canadian Air Force]]
 |status= 
 |primary_user= [[Royal Air Force]]
 |more_users= [[Royal Canadian Air Force]]<br />[[Royal Australian Air Force]]
 |produced=
 |number_built= 7,377<ref name = "norris 13-14">Norris 1966, pp. 13–14.</ref>
 |developed_from= [[Avro Manchester]]
 |variants = [[Avro Lancastrian]]
 |developed_into= [[Avro York]]<br />[[Avro Lincoln]]
}}

The '''Avro Lancaster''', commonly known as the '''Lancaster Bomber''', 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 [[Short Stirling]], all three aircraft being four-engined heavy bombers adopted by the [[Royal Air Force]] (RAF) during the same era.

The Lancaster has its origins in the twin-engine [[Avro Manchester]] which had been developed during the late 1930s in response to the [[Air Ministry]] [[List of Air Ministry specifications|Specification P.13/36]] for a [[medium bomber]] for "world-wide use" which could carry a torpedo internally, and make shallow dive-bombing attacks. Originally developed as an evolution of the Manchester (which had proved troublesome in service and was retired in 1942), the Lancaster was designed by [[Roy Chadwick]] and powered by four [[Rolls-Royce Merlin]]s and in one of the versions, [[Bristol Hercules]] engines. It first saw service with [[RAF Bomber Command]] in 1942 and as the [[Strategic bombing during World War II|strategic bombing offensive]] over Europe gathered momentum, it was the main aircraft for the night-time bombing campaigns that followed. As increasing numbers of the type were produced, it became the principal [[heavy bomber]] used by the RAF, the [[Royal Canadian Air Force]] (RCAF) and squadrons from other [[Commonwealth of Nations|Commonwealth]] and European countries serving within the RAF, overshadowing the Halifax and Stirling, two other commonly used bombers.<ref>McKinstry 2009, pp. 9–10.</ref>

A long, unobstructed bomb bay meant that the Lancaster could take the largest bombs used by the RAF, including the {{cvt|4000|lb}}, {{cvt|8000|lb}} and {{cvt|12000|lb}} "[[Blockbuster bomb|blockbusters]]", loads often supplemented with smaller bombs or [[Incendiary device|incendiaries]]. The "Lanc", as it was known colloquially,<ref>Cotter 2005, p. xiii.</ref> became one of the most heavily used of the Second World War night bombers, delivering {{cvt|608612|LT|kg}} of bombs in 156,000 sorties.<ref>Taylor 1969, p. 314.</ref> The versatility of the Lancaster was such that it was chosen to equip [[No. 617 Squadron RAF|617 Squadron]] and was modified to carry the [[Bouncing bomb|Upkeep]] "bouncing bomb" designed by [[Barnes Wallis]] for [[Operation Chastise]], the attack on German [[Ruhr Area|Ruhr valley]] dams. Although the Lancaster was primarily a night bomber, it excelled in many other roles, including daylight precision bombing, for which some Lancasters were adapted to carry the {{cvt|12000|lb}} [[Tallboy (bomb)|Tallboy]] and then the {{cvt|22000|lb}} [[Grand Slam (bomb)|Grand Slam]] [[earthquake bomb]]s (also designed by Wallis).<ref name="Granfilm">[https://www.youtube.com/watch?v=R-Mm-zFW_nA&feature=relmfu "Second World War propaganda film of "Grand Slam" in action."] ''youtube.com.'' Retrieved: 3 January 2012.</ref> This was the largest payload of any bomber in the war.

In 1943, a Lancaster was converted to become an engine test bed for the [[Metropolitan-Vickers F.2]] [[turbojet]]. Lancasters were later used to test other engines, including the [[Armstrong Siddeley Mamba]] and [[Rolls-Royce Dart]] [[turboprop]]s and the [[Avro Canada Orenda]] and [[STAL Dovern]] turbojets. Postwar, the Lancaster was supplanted as the main strategic bomber of the RAF by the [[Avro Lincoln]], a larger version of the Lancaster. The Lancaster took on the role of long range [[anti-submarine]] patrol aircraft (later supplanted by the [[Avro Shackleton]]) and air-sea rescue. It was also used for photo-reconnaissance and aerial mapping, as a flying tanker for [[aerial refuelling]] and as the [[Avro Lancastrian]], a long-range, high-speed, transatlantic passenger and postal delivery airliner. In March 1946, a Lancastrian of [[British South American Airways|BSAA]] flew the first scheduled flight from the new [[London Heathrow Airport]].<ref>[http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200093.html "First to South America."] ''Flight,'' 20 January 1946.</ref>
{{TOC limit|4}}

==Development==
===Origins===
In the 1930s, the [[Royal Air Force]] (RAF) was primarily interested in twin-engine [[bombers]].<ref name = "norris 3"/> These designs put limited demands on engine production and maintenance, both of which were already stretched with the introduction of so many new types into service. Power limitations were so serious that the British invested heavily in the development of huge engines in the {{cvt|2000|hp}} class in order to improve performance. During the late 1930s, none of these were ready for production. Both the [[United States]] and the [[Soviet Union]] were pursuing the development of bombers powered by arrangements of four smaller engines; the results of these projects proved to possess favourable characteristics such as excellent range and fair lifting capacity. Accordingly, in 1936, the RAF also decided to investigate the feasibility of the four-engined bomber.<ref name = "norris 3">Norris 1966, p. 3.</ref>

The origins of the Lancaster stem from a twin-engined bomber that had been submitted to British [[Air Ministry]] [[List of Air Ministry specifications|Specification P.13/36]] of 1936 for a twin-engined [[medium bomber]] for "worldwide use" which could carry a torpedo internally, and make shallow dive-bombing attacks.<ref name="Mason Bomber p324-5">Mason 1994, pp. 324–325.</ref><ref name = "robertson1964 7">Robertson 1964, p. 7.</ref> Further requirements of the specification included the use of a mid-mounted [[cantilever]] [[monoplane]] wing, and all-metal construction while the use of the [[Rolls-Royce Vulture]], which was in development was encouraged.<ref name="moyes 3">Moyes 1966, p. 3.</ref> Twin-engine designs were submitted by [[Fairey Aviation Company|Fairey]], [[Boulton Paul Aircraft|Boulton Paul]], [[Handley Page]] and [[Short Brothers|Shorts]], using [[Rolls-Royce Vulture]], [[Napier Sabre]], [[Fairey P.24]] or [[Bristol Hercules]] engines. Most of these engines were still under development and while four-engined bomber designs were considered for specification B.12/36 for a heavy bomber, the extra engines required the wing and overall aircraft structure to be stronger, increasing the structural weight.<ref>Buttler 2004, p. 104.</ref>

[[Avro]] submitted the [[Avro Manchester|Avro 679]] to fulfil Specification P.13/36 and, in February 1937, Avro's submission was selected, along with Handley Page's bid as a backup. In April 1937, a pair of prototypes for each design was ordered.<ref>Buttler 2004, p. 102.</ref><ref name="moyes 3"/> Avro's aircraft, named the Manchester, entered RAF service in November 1940. Although a capable aircraft, the Manchester was underpowered and its Vulture engines proved to be unreliable.<ref name="goul garb 3">Goulding and Garbett 1966, p. 3.</ref><ref name = "robertson1964 911">Robertson 1964, pp. 9–11.</ref> As a result, only 200 were constructed and the type was withdrawn from service in 1942.<ref name="Jackson Avro p355-6">Jackson 1990, pp. 355–356.</ref>

===Flight testing===
By mid-1940, Avro's chief design engineer, [[Roy Chadwick]], was working on an improved Manchester<ref name="goul garb 3"/> powered by four of the more reliable but less powerful [[Rolls-Royce Merlin]] engines, specifically adopting the [[Power-egg#United Kingdom|"Power-egg"]] installation developed for the [[Bristol Beaufighter|Beaufighter II]], and installed on a wing of increased span.<ref>[[Bill Gunston|Gunston]] 2006, p. 190.</ref> Initially, the improved aircraft was designated as the ''Type 683 Manchester III'' but was subsequently renamed the [[Lancaster, Lancashire|Lancaster]]. The prototype, [[United Kingdom military aircraft serial numbers|serial number]] ''BT308'', was assembled by the Avro experimental flight department at [[Ringway Airport]], [[Manchester]], being modified from a production Manchester airframe, combined with the new wing to accommodate the additional engines.<ref name="goul garb 3"/> The first flight was made by test pilot H. A. "Sam" Brown on 9 January 1941 at [[RAF Ringway]], [[Cheshire]].<ref name = "robertson1964 14">Robertson 1964, p. 14.</ref>

[[File:Avro Lancaster bombers nearing completion at the A V Roe & Co Ltd factory at Woodford in Cheshire, 1943. TR1386.jpg|thumb|Lancasters on Avro's Woodford assembly line at Cheshire, 1943]]
Flight testing of the new aircraft quickly proved it to be a substantial improvement over its predecessor.<ref>Winchester 2005, p. 27.</ref> The first prototype was initially outfitted with the Manchester I's three-finned tail but this was revised on the second prototype, ''DG595'', and subsequent production Lancasters used the larger elliptical [[twin tail|twin-finned]] tail unit that was also adopted for the last Manchesters built.<ref name="goul garb 3"/> This not only increased stability but also improved the dorsal gun turret's field of fire. The second prototype was also fitted with more powerful Merlin XX engines.<ref name="goul garb 3"/>

Manchesters still on the production line were converted into Lancaster B.Is.<ref name="goul garb 3"/><ref name = "robertson1964 14"/> Based upon its performance, a decision was taken early on to reequip twin-engine bomber squadrons with the Lancaster as quickly as possible.<ref name="goul garb 3"/> ''L7527'', The first production Lancaster made its first flight in October 1941, powered by Merlin XX engines.<ref name="goul garb 3"/><ref name = "robertson1964 14"/>

===Production===
[[File:Avro Lancaster aircraft under construction at the A V Roe & Co Ltd factory at Woodford in Cheshire, 1943. TR1384.jpg|thumb|upright|Lancasters under construction at Avro's factory at Woodford, Cheshire, 1943]]
Avro received an initial contract for 1,070 Lancasters.<ref name="goul garb 3"/> The majority of Lancasters manufactured during the war years were constructed by Avro at its factory at [[Chadderton]] near [[Oldham]], [[Lancashire]] and were test-flown from [[Woodford Aerodrome]] in [[Cheshire]]. As it was quickly recognised that Avro's capacity was exceeded by the wartime demand for the type, it was decided to form the ''Lancaster Aircraft Group'', which comprised a number of companies that undertook the type's manufacture, either performing primary assembly themselves or producing various subsections and components for the other participating manufacturers.<ref name="goul garb 3 4">Goulding and Garbett 1966, pp. 3–4.</ref> [[Wythenshawe Bus Garage]], built of [[reinforced concrete]] during 1939–42 and designed by the Manchester [[City Architect]], [[G. Noel Hill]], was immediately taken over by the [[Ministry of Aircraft Production]] and Avro used it in its Lancaster aircraft production.<ref name="wythenshawe-bus-garage">{{cite web| url= https://manchestervictorianarchitects.org.uk/buildings/wythenshawe-bus-garage-manchester | title=Wythenshawe Bus Garage Manchester | work=A Biographical Dictionary of the Architects of Greater Manchester, 1800–1940 | first=Neil | last=Darlington | publisher=[[The Victorian Society]] | date=2024 | accessdate=30 December 2024 }}</ref>

In addition to Avro, further Lancasters were constructed by [[Metropolitan-Vickers]] (1,080, also tested at Woodford) and [[Armstrong Whitworth]]. They were also produced at the [[Austin Motor Company]] works in [[Longbridge]], [[Birmingham]], later in the Second World War and post-war by [[Vickers-Armstrongs]] at [[Chester]] as well as at the Vickers Armstrong factory, Castle Bromwich, Birmingham. [[Belfast]]-based aircraft firm [[Short Brothers]] had also received an order for 200 Lancaster B.Is, but this was cancelled before any aircraft had been completed.<ref name="goul garb 4">Goulding and Garbett 1966, p. 4.</ref><ref name = "robertson1964 7981">Robertson 1964, pp. 79–81.</ref>

The Lancaster was also produced overseas. During early 1942, it was decided that the bomber should be produced in Canada, where it was manufactured by [[Victory Aircraft]] in [[Malton, Ontario]].<ref name="goul garb 5"/> Of later variants, only the Canadian-built ''Lancaster B X'' was produced in significant numbers. A total of 430 of this type were built, earlier examples differing little from their British-built predecessors, except for using [[Packard]]-built [[Rolls-Royce Merlin|Merlin]] engines and American-style instruments and electrics.{{citation needed|date=July 2015}} In August 1942, a British-built Lancaster B.I was dispatched to Canada as a pattern aircraft, becoming the first of the type to conduct a [[transatlantic crossing]].<ref name="goul garb 5" /> The first Lancaster produced in Canada was named the "Ruhr Express".{{NoteTag|The "Ruhr Express" the subject of a Canadian National Film Board production ''Target Berlin'' for the [[Canada Carries On]] series, filmed in part over Berlin by NFB cameraman [[Grant McLean (film producer)|Grant McLean]].{{citation needed|date=July 2015}}}}{{citation needed|date=July 2015}} The first batch of Canadian Lancasters delivered to England suffered from faulty ailerons; this error was subsequently traced to the use of unskilled labour.<ref name="Wings on my Sleeve p80">Brown 2016, p. 80.</ref> By the end of the conflict, over 10,000 Canadians were employed on the production line, which was producing one Lancaster each day.<ref name = "robertson1964 81">Robertson 1964, p. 81.</ref>

{| class="wikitable"
|+Production by factory
!Manufacturer
!Location
!Number produced
|-
| rowspan="3" |[[Avro|A. V. Roe]]
|[[Woodford, Greater Manchester|Woodford]]
| rowspan="2" |2,978
|-
|[[Chadderton]]
|-
|[[Yeadon, West Yorkshire|Yeadon]]
|695
|-
|[[Armstrong Whitworth]]
|[[Whitley, Coventry|Whitley]]
|1,329
|-
| rowspan="2" |[[Austin Motors]]
|[[Longbridge]]
| rowspan="2" |330
|-
|[[Marston Green]]
|-
|[[Metropolitan-Vickers]]
|[[Trafford Park]]
|1,080
|-
| rowspan="2" |[[Vickers-Armstrongs]]
|[[Castle Bromwich]]
|300
|-
|[[Chester]]
|235
|-
|[[Victory Aircraft]]
|[[Malton, Ontario|Malton]] (Canada)
|430
|}

===Further development===
[[File:Avro Lancaster B I PA474.jpg|thumb|left|PA474, Lancaster B.I of the RAF Battle of Britain Memorial Flight]]
The Lancaster B.I was never fully superseded in production by a successor model, remaining in production until February 1946.<ref name="goul garb 4"/> According to aviation authors Brian Goulding and M. Garbett, the Lancaster B.I altered little during its production life, partially as a result of the sound basic structure and design; of the visible changes, the fuselage side windows were deleted, the [[Perspex]] chin of the bomb-aimer was enlarged, and a larger [[Astrodome (aeronautics)|astrodome]] was provided.<ref name="goul garb 4 5"/> Various additional bumps and [[blister]]s were also added, which typically housed [[radar]] equipment and [[radio]] navigational aids. Some Lancaster B.I bombers were outfitted with bulged bomb bay doors in order to accommodate increased armament payloads.<ref name="goul garb 4 5">Goulding and Garbett 1966, pp. 4–5.</ref>

Early production Lancaster B.Is were outfitted with a ventral gun turret position.<ref name="goul garb 5"/> In response to feedback on the lack of application for the ventral turret, the ventral turret was often eliminated during the course of each aircraft's career. While some groups chose to discard the position entirely, various trials and experiments were performed at [[Duxford Aerodrome|RAF Duxford]], [[Cambridgeshire]] and by individual squadrons.<ref name="goul garb 5"/> A total of 50 Austin-built Lancaster B.Is was constructed to a non-standard configuration, having a Frazer Nash turret installed directly above the bomb bay; however, this modification was largely unpopular due to its obstruction of the internal walkway, hindering crew movements. Various other turret configurations were adopted by individual squadrons, which included the removal of various combinations of turrets.<ref name="goul garb 5 6">Goulding and Garbett 1966, pp. 5–6.</ref>

The ''Lancaster B.III'' was powered by [[Packard V-1650|Packard Merlin]] engines, which had been built overseas in the [[United States]], but was otherwise identical to contemporary B.Is.<ref name="goul garb 4"/> In total, 3,030 B.IIIs were constructed, almost all of them at Avro's [[Newton Heath]] factory. The Lancaster B.I and B.III were manufactured concurrently and minor modifications were made to both marks as further batches were ordered. The B.I and B.III designations were effectively interchangeable simply by changing the engines used, which was occasionally done in practice.<ref name="goul garb 4"/> Examples of modifications made include the relocation of the [[Pitot tube|pitot head]] from the nose to the side of the cockpit and the change from de Havilland "needle blade" propellers to [[Hamilton Standard]] or [[Nash-Kelvinator Corporation|Nash Kelvinator]] made "paddle blade" propellers.<ref>"The Design and Development of the Avro Lancaster". ''Manchester Branch of the Royal Aeronautical Society''.</ref>

==Design==

===Overview===
[[File:The Royal Air Force in Britain, 29 September 1942 TR197.jpg|thumb|Three 44 Squadron Avro Lancaster B.Is in 1942]]
The Avro Lancaster was a British four-engined [[Strategic bomber#World War II|strategic bomber]] that was used as the RAF's principal heavy bomber during the latter half of the Second World War. The typical aircraft was powered by an arrangement of four wing-mounted [[Rolls-Royce Merlin]] piston engines, each of which drove a {{cvt|13|ft|m}} diameter [[de Havilland]] Hydromatic three-bladed [[propeller]]. While not optimal, the Lancaster was capable of flying the return journey home on only two operational engines, along with very limited distances on a single running engine.<ref name="goul garb 4"/> Aviation authors Brian Goulding and M. Garbett have claimed that experienced Lancaster pilots were often able to out-manoeuver Luftwaffe fighters.<ref name="goul garb 6"/> It possessed largely favourable flying characteristics, having been described by Goulding and Garbett as being: "a near-perfect flying machine, fast for its size and very smooth...such a delightfully easy aeroplane to fly...there are instances of Lancasters having been looped and barrel-rolled, both intentionally and otherwise".<ref name="goul garb 6">Goulding and Garbett 1966, p. 6.</ref>

The Lancaster benefited from a structure that possessed considerable strength and durability, which had been intentionally designed to maximise structural strength-per-weight; this resulted in the Lancaster being capable of withstanding some levels of damage resulting from attacks by hostile [[interceptor aircraft]] and ground-based [[anti-aircraft warfare|anti-aircraft batteries]].<ref name="goul garb 4"/> However, during the first year of the type's career, some instances of structural failures were encountered on Lancaster B.Is and a number of aircraft were lost in accidents as a result of the design limitations having been greatly exceeded.<ref name="goul garb 6"/> Compared with other contemporary aircraft, the Lancaster was not an easy aircraft to escape from as its escape hatch was only {{cvt|22|x|26.5|in|cm}} in size; in a Halifax or Stirling (which both had an escape hatch {{cvt|2|in|cm}} wider), 25 per cent of downed aircrew bailed out successfully, and in American bombers (albeit in daylight raids) it was as high as a 50 per cent success rate while only 15 per cent of the Lancaster crew were able to bail out.<ref>Iveson 2009, p. 221.</ref>
[[File:Lancaster landing gear retraction and extension video.webm|thumb|Video of the Lancaster landing gear retraction and extension, ex-situ.]]
The Lancaster uses a mid-wing [[Cantilever#Aircraft|cantilever]] [[monoplane]] configuration. The wing is constructed from five separate main sections while the fuselage is likewise composed of five sections. Aside from a few elements, such as the [[fabric]]-covered [[aileron]]s, the Lancaster's oval-shaped fuselage had an all-metal covering.<ref name="goul garb 5">Goulding and Garbett 1966, p. 5.</ref> All of the wing and fuselage sections were manufactured separately, during which they were outfitted with all of the required equipment in advance of final assembly being performed, as a measure intended to accelerate the rate of production. The Lancaster was equipped with a retractable main [[landing gear|undercarriage]] and fixed tailwheel; the [[hydraulics|hydraulically]]-actuated main landing gear raised rearwards into recesses within the inner engine nacelles.<ref name="janes">Bridgman 1988, pp. 105–106.</ref> The distinctive tail unit of the aircraft was outfitted with a large twin elliptical fins and [[rudder]] arrangement.<ref name="goul garb 6"/>

Like any aeroplane, the Lancaster was not viceless in its handling. In a dive, it had a tendency to go more deeply into the dive as speed increased. Not all aeroplanes did this, for example, the Halifax tended to get increasingly tail-heavy as speed increased, and thus fly itself out of the dive.<ref>{{cite book |last1=Bingham |title=Halifax - Second to none |publisher=Airlife |pages=71}}</ref> Furthermore, the Lancaster suffered longitudinal instability at speeds above {{cvt|200|mph}}.<ref>{{cite book |last1=Bingham |title=Halifax - Second to none |publisher=Airlife |pages=74}}</ref>

===Crew accommodation===
The standard crew for a Lancaster consisted of seven men, stationed in various positions in the fuselage. Starting at the nose, the [[Bombardier (air force)|bomb aimer]] had two positions to man. His primary location was lying prone on the floor of the nose of the aircraft, with access to the [[bombsight]] controls facing forward, with the [[Mark XIV bomb sight]] on his left and bomb release selectors on the right. He also used his view through the large transparent perspex nose cupola to assist the navigator with map reading.{{citation needed|date=April 2017}} To man the Frazer Nash FN5 nose turret, he stood up placing himself in position behind the triggers of the twin .303&nbsp;in (7.7&nbsp;mm) guns. Ammunition for the turret was 1,000 rounds per gun (rpg). The bomb aimer's position contained the nose emergency hatch in the floor; at {{convert|22|by|26.5|in|cm}} (two inches narrower than the Halifax escape hatch) it was difficult to exit through while wearing a parachute. [[Operational research]] experts, including British scientist [[Freeman Dyson]], amongst others, attempted unsuccessfully to have the escape hatch enlarged.{{citation needed|date=April 2017}}
{{multiple image|image_caption_align=left
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On the roof of the [[bomb bay]] the pilot and [[flight engineer]] sat side by side under the expansive canopy, with the pilot sitting on the left on a raised portion of the floor (almost all British bombers, and most German bombers, had only a single pilot seat as opposed to the American practice of carrying two pilots, or at least having controls for two pilots installed). The flight engineer sat on a collapsible seat (known as a "second [[dicky seat]]") to the pilot's right, with the fuel selectors and gauges on a panel behind him and to his right. The pilot and other crew members could use the panel above the cockpit as an auxiliary emergency exit while the mid-upper gunner was expected to use the rear entrance door to leave the aircraft. The tail gunner escaped by rotating his turret to the rear, opening the door in the back of the turret, passing into the fuselage, and clipping on a parachute that was hung on the side wall. He could then exit through the rear entrance door.<ref>Neillands 1995, p. 109.</ref>

[[File:Royal Air Force Bomber Command, 1941-1945. CH8789.jpg|thumb|Bomb aimer in his position in the nose]]
[[File:G for George wireless operator and navigator AWM UK2052.jpg|thumb | Inside [[G for George]] of [[No. 460 Squadron RAAF|No. 460 Squadron]]. Looking forward between wing spars. At left is the wireless operator, and at right is the navigator]]
Behind the pilot and flight engineer, and behind a curtain fitted to allow him to use light to work, sat the [[navigator]]. His position faced to port with a chart table in front of him. An instrument panel showing the airspeed, altitude, and other information required for navigation was mounted on the side of the fuselage above the chart table. The [[wireless]] operator's radios were mounted on the left-hand end of the chart table, facing the rear of the aircraft. Behind these and facing forwards the wireless operator sat on a seat at the front of the main spar. On his left was a window, and above him was the [[Astrodome (aviation)|astrodome]], used for visual signalling and by the navigator for [[celestial navigation]].<ref>{{Cite web |date=21 October 1996 |title=A History of Navigation in the Royal Air Force |url=https://www.rafmuseum.org.uk/documents/research/RAF-Historical-Society-Journals/Journal-17A-Air-Navigationin-the-RAF.pdf |website=Royal Air Force |place=RAF Historical Society Seminar at the RAF Museum, Hendon}}</ref>{{Page requested|date=August 2024}}

Behind the wireless operator were the two [[Spar (aviation)|spars]] of the wing, which created a major obstacle for crew members moving down the fuselage even on the ground. At the end of the bomb bay was the mid-upper gunner's turret, at which the floor dropped down to the fuselage's bottom. His position allowed a 360° view over the top of the aircraft, with two [[M1919 Browning machine gun#Browning .303 Mark II|Browning .303 Mark IIs]] to protect the aircraft from above and to the side. The mid-upper gunner sat on a rectangle of canvas that was slung beneath the turret and would stay in position throughout the flight. The turret had 1,000 rounds of ammunition per gun.{{citation needed|date=May 2016}}

To the rear of the turret was the side crew door, on the starboard side of the fuselage. This was the main entrance to the aircraft, and also could be used as an emergency exit. The Elsan [[chemical toilet]], a type of [[aircraft lavatory]], was located near the spars for the tailplane. At the extreme tail-end of the fuselage, the rear gunner sat in his exposed position in the tail turret, which was entered through a small hatch in the rear of the fuselage. Depending on the size of the rear gunner, the area was so cramped that the gunner would often hang his parachute on a hook inside the fuselage, near the turret doors. Neither the mid-upper nor the rear gunner's position was heated, and the gunners had to wear electrically heated suits to prevent [[hypothermia]] and [[frostbite]].{{citation needed|date=May 2016}}

===Armament===

====Defensive armament====
[[File:Lancaster Mk I gun positions.jpg|thumb|upright=1.3|left|Battle of Britain Flight Lancaster Mk I ''PA474'' in flight showing nose, dorsal and tail .303 Browning gun positions]]
The Avro Lancaster was initially equipped with four [[Nash & Thompson]] [[Frazer Nash]] [[Hydraulic machinery|hydraulically]] operated turrets mounted in the nose, tail, mid-upper and underside. The original tail turret was equipped with four [[M1919 Browning machine gun#Browning .303 Mark II|Browning .303 Mark II]] machine guns and all other turrets with two such machine guns.<ref name="Lanc Story">Jacobs 1996{{page needed|date=January 2012}}</ref><ref name="Franks">Franks 2000, p. 83.</ref><ref name="goul garb 16"/>

Late on in the war, [[Freeman Dyson]] (as a 19-year-old who had yet to win a degree) put forward a case for the removal of the majority of the Lancaster's defensive armament. He argued that this would reduce the loss rate by increasing the Lancaster's cruising speed by up to {{cvt|50|mph}} (assuming the bomb load was not increased), making the bomber harder to intercept.<ref>Iveson 2009, p. 222.</ref> He also claimed reducing defensive air gunners would reduce human losses incurred with each aircraft lost.<ref>[[Freeman Dyson]], "The Children's Crusade" in ''Disturbing the Universe'', 1979.</ref> However this neglects the fact that the two main Luftwaffe [[night fighter]]s of the time, the [[Messerschmitt Bf 110]] and the [[Junkers Ju 88]] night fighters were capable of over {{cvt|300|mph}}, thus a {{cvt|50|mph}} increase over the Lancaster's normal cruising speed of around {{cvt|180|mph}}, giving a speed of {{cvt|230|mph}}, still left the Lancaster vulnerable to interception. The introduction of the [[Heinkel He 219]] and the jet-powered [[Messerschmitt Me 262]] erased any speed advantage and would have left the aircraft undefended. Consequently, Dyson's proposal was not adopted.

=====Nose turret=====
{{multiple image|align=right|total_width=380
|image1=A gun turret on a restored WW2 Lancaster bomber -b.jpg| width1=453|image_caption1=Mk.X nose with twin .303 Brownings in turret over bomb-aimer's position
|image2=Lancaster mk X-IMG 6218.jpg|width2=473|image_caption2=Nose turret from above, and bomber aimer's station
}}
Only the FN-5A<ref name="Lanc Story" /> nose turret which was similar to the FN-5 used on the preceding [[Avro Manchester]], the [[Vickers Wellington]] and the [[Short Stirling]] remained unchanged during the life of the design, except where it was removed.

=====Ventral turret=====
The ventral (underside) FN-64 turret quickly proved to be dead weight, being both difficult to sight because it relied on a periscope which limited the gunner's view to a 20-degree arc,<ref name="Lanc Story" /> and too slow to keep a target within its sights.{{NoteTag|Similar view and speed problems were commonplace in the era, having particularly afflicted the ventral turret in the [[North American B-25 Mitchell]] and other bombers.{{citation needed|date=July 2015}}}} Aside from early B.Is and the prototype B.IIs, the FN-64 was almost never used. When the [[Luftwaffe]] began using ''[[Schräge Musik]]'' to make attacks from below in the winter of 1943/1944, modifications were made, including downward observation blisters mounted behind the bomb aimer's blister<ref>Mod 913, Avro Manufacturing Drawing Z2511</ref> and official<ref>Mod 925, shown on Avro Manufacturing Drawing X815</ref> and unofficial mounts for {{cvt|.50|in|1}} machine guns or even {{cvt|20|mm}} cannon, firing through the ventral holes of the removed FN-64. The fitting of these guns was hampered as the same ventral position was used for mounting the [[H2S radar|H2S]] blister, which limited installations to those aircraft fitted with bulged bomb bays which interfered with the H2S.<ref name="Lanc Story" />

=====Mid-upper turret=====
[[File:A No. 57 Squadron Lancaster mid-upper gunner in his turret, February 1943. CH8795.jpg|thumb|Gunner in Fraser Nash FN50 mid-upper turret with twin .303 Brownings, February 1943]]
The mid-upper (dorsal or top) turret was an FN-50<ref name="Lanc Story" /><ref name="Franks" /> on early examples and the very similar FN-150 with improved sights and controls<ref name="Lanc Story" /> on later examples. On all but the earliest examples, this turret was surrounded by a coaming which provided a track for a cam-operated interrupter device which prevented the gunner from shooting the tail of his own aircraft.<ref name="Lanc Story" /> The Mk.VII and late Mk.X Lancasters used the heavier, electrically controlled Martin 250 CE 23A turret equipped with two {{cvt|.50|in}} machine guns<ref name="Lanc Story" /> which was mounted further forward to preserve the aircraft's longitudinal balance, and because it had an internal mechanism to prevent firing on the aircraft itself, it did not require a coaming.{{NoteTag|The Martin 250 CE 23A turret was the same unit which had been equipped upon many American bombers, such as the [[Consolidated B-24 Liberator]].{{citation needed|date=July 2015}}}}<ref name="Lanc Story" /> Other experimental turrets were tried out, including the FN-79 and the Boulton-Paul Type H barbette system.<ref name="Lanc Story" />

=====Tail turret=====
[[File:Lancaster tail gunner IWM CH 12776.jpg|thumb|upright|Gunner in the Nash & Thompson FN20 tail turret]]

The tail turret was the most important defensive position and carried the heaviest armament. Despite this, the turrets used, starting with the FN-20, were never entirely satisfactory and numerous designs were tried. The FN-20 was replaced by the very similar FN-120 which used an improved [[Gyro gunsight|gyroscopic gun sight]] (GGS).<ref name="Lanc Story" /> Many rear gunners insisted on having the centre section of [[Acrylic glass|perspex]] removed from the turret to improve visibility. The transparencies were difficult to see through at night, particularly when trying to keep watch for enemy night fighters that appeared without notice astern and below the aircraft when getting into position to open fire. This removal of perspex from the turret was called the "[[Gransden Lodge Airfield|Gransden Lodge]]" modification. Ammunition for the tail turret was 2,500 rounds per gun. Due to the weight, the ammunition was stored in tanks situated near the mid-upper turret's position and fed rearward in runways down the back of the fuselage to the turret.<ref>Stiriling, Neil. [http://www.wwiiaircraftperformance.org/Lancaster/Lancaster_I_III_ADS-b.jpg "Lancaster I/III data card."] ''wwiiaircraftperformance.org.'' Retrieved: 6 August 2013.</ref>

[[File:Rose Gun Turret RAF Museum London.JPG|thumb|left|The [[Rose turret]]]]
Gunners using both the FN-20 and 120 removed perspex and armour from the turret to improve visibility, but trials by the RAF showed that a [[de Havilland Mosquito]] night fighter was still able to get within a very short distance of the tail gunner without being spotted, confirming what the Luftwaffe had already realised. The [[Rose turret]] attempted to improve on the FN turrets by being completely open to the rear (improving visibility and allowing easier emergency egress) and by being fitted with two {{cvt|.50|in}} machine guns. It was installed in a small number of Lancasters but never became common.<ref name="Lanc Story" />

Ultimately radar, rather than improved visibility, made the turret more effective. The FN-121 was the Automatic Gun Laying Turret (AGLT), an FN-120 fitted with [[Village Inn (codename)|'Village Inn']] gun-laying [[radar]].<ref name="Lanc Story" /> Aircraft fitted with Village Inn were used as bait, flying behind the main formations to confront the night fighters that followed the formations and shot down stragglers. This significantly reduced operational losses; and gun-laying radar was added to the last versions of the turret. Before the end of the war, Lancasters built in the UK standardised on the FN-82 fitted with two {{cvt|.50|in}} machine guns and a gun-laying radar as production allowed, which was also used on early models of the Avro Lincoln. The disadvantage of all radar and radio transmitting systems is that attacking forces can locate aircraft by picking up transmissions.{{citation needed|date=April 2017}}

====Bombs====
{{multiple image|image_caption_align=left
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 | image_caption2 =''"Usual"'' [[area bombardment]] load – a 4,000-pound [[Blockbuster bomb|"Cookie" blast bomb]] with 12 Small Bomb Containers, each with 236 4-lb incendiary bombs<ref>{{cite web | url=http://www.iwm.org.uk/collections/item/object/205210816 | title=Royal Air Force Bomber Command, 1942–1945. CH18371 | publisher=Imperial War Museum | access-date=16 January 2016}}</ref>
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An important feature of the Lancaster was its unobstructed {{cvt|33|ft}} long bomb bay. At first, the heaviest bomb carried was the {{cvt|4000|lb}} high capacity HC "[[Blockbuster bomb|Cookie]]".<ref>[https://books.google.com/books?id=0SkDAAAAMBAJ&pg=PA48-IA3 "The Kite That Smashed Berlin"]. ''Popular Sciences'', March 1944, pp. 48C–48H.</ref> Bulged doors were added to 30 per cent of B.Is to allow the aircraft to carry {{cvt|8000|lb}} and later {{cvt|12000|lb}} "Cookies". The Lancaster also carried a variety of smaller weapons, including the Small Bomb Container (SBC) which held 236 {{cvt|4|lb}} or 24 {{cvt|30|lb}} incendiary and explosive incendiary bomblets; {{cvt|500|lb}} and {{cvt|1000|lb}} [[General-purpose bomb|General Purpose High Explosive (GP/HE) bombs]] (these came in a variety of designs); {{cvt|1850|lb}} parachute deployed [[magnetic mine|magnetic]] or [[acoustic mine|acoustic]] mines, or {{cvt|2000|lb}} armour-piercing (AP) bombs; {{cvt|250|lb}} Semi-Armour-Piercing (SAP) bombs, used up to 1942 against submarines; post-1942: {{cvt|250|lb}} or {{cvt|500|lb}} anti-submarine [[depth charge]]s.{{citation needed|date=May 2016}}

In 1943, [[No. 617 Squadron RAF|617 Squadron]] was created to carry out [[Operation Chastise]], the raid against the Ruhr dams. This unit was equipped with B.III (Specials), officially designated the "Type 464 (Provisioning)", modified to carry the {{cvt|9250|lb}} [[Bouncing bomb|"Upkeep" bouncing bomb]].<ref>McKinstry 2009, p. 265.</ref>{{NoteTag|In period material, the "Upkeep" [[bouncing bomb]] was frequently referred to as being a [[naval mine|mine]], rather than as a bomb.{{citation needed|date=May 2016}}}} The bomb bay doors were removed and the ends of the bomb bay were covered with fairings. "Upkeep" was suspended on laterally pivoted, vee-shaped struts which sprang apart beamwise when the bomb-release button was pressed. A drive belt and pulley to rotate the bomb at 500 rpm was mounted on the starboard strut and driven by a hydraulic motor housed in the forward fairing. The mid-upper turret was removed and a more bulbous bomb aimer's blister was fitted; this, as "Mod. 780", later became standard on all Lancasters, while the bombsight was replaced by a simple aiming device that consisted of a simple triangle of wood with a peephole at one corner and a nail in each of the other corners such that at the correct distance the nails coincided with the towers on the dams. Because each dam was a different width between the towers, each plane carried two or three different sights.<ref name="auto">Brickhill 1951, {{page needed|date=June 2020}}.</ref><ref>McKinstry 2009, p. 268.</ref> Two [[Signal lamp|Aldis lights]] were fitted in the rear bomb bay fairing, aimed forward so the bomb aimer could see the converging lights below his blister in the nose; the optimum height for dropping "Upkeep" was {{cvt|60|ft}} and, when shone on the relatively smooth waters of the dam's reservoirs, the light beams converged into a figure 8 when the Lancaster was flying at the correct height.<ref name="auto"/><ref>McKinstry 2009, p. 275.</ref>
The Type 464 Lancaster was also fitted with [[VHF|VHF radios]] (normally reserved for fighters) so that [[Guy Gibson|Gibson]], the squadron leader, could control the operation while over the target,<ref>Leo McKinstry (2010) ''Lancaster'' John Murray Publishers {{ISBN| 978-0-7195-2363-2}}. p. 277</ref> an early example of what became the [[master bomber]] role.

After the 'Dam Busters' raid 617 Squadron was converted to a high-altitude precision bombing squadron in preparation for the arrival of Barnes Wallis's forthcoming Earthquake bombs for attacking special and hardened targets, and while they were training for this the bouncing bomb variants of B.I Specials had the spars and equipment removed and were then modified to carry the {{cvt|21|ft}} long {{cvt|12000|lb}} [[Tallboy (bomb)|"Tallboy"]] bomb, a scaled-down version of the upcoming {{cvt|25.5|ft}} long {{cvt|22000|lb}} [[Grand Slam (bomb)|"Grand Slam"]] "earthquake" bombs which were still being built. Aircraft intended to carry the "Grand Slam" required extensive modifications. These included the removal of the dorsal turret and of two guns from the rear turret, the removal of the cockpit armour plating (the pilot's seatback), and the installation of Rolls-Royce Merlin Mk 24 engines for better take-off performance. The bomb bay doors were removed and the rear end of the bomb bay cut away to clear the tail of the bomb. Later the nose turret was also removed to further improve performance. A strengthened undercarriage and stronger mainwheels, later used by the [[Avro Lincoln]], were fitted.<ref name="Granfilm" />{{NoteTag|The weight in kilograms of the "Tall Boy" and "Grand Slam" bombs differs according to their source. The figures given are the most common.{{citation needed|date=July 2015}}}}

Specific bomb loads were standardised and given code names by Bomber Command:<ref>Mason, Francis K.
[http://www.lancaster-archive.com/lanc_bomb_loads.htm "Lancaster: Bomb Loads."] ''The Avro Lancaster'', 1990, February 2008. Retrieved December 2011.</ref>
[[File:Lancaster I NG128 Dropping Load - Duisburg - Oct 14 - 1944.jpg|thumb|Lancaster B.I of [[No. 101 Squadron RAF]] dropping bundles of '[[Chaff (countermeasure)|Window]]' followed by {{cvt|30|lb}} incendiaries and a [[Blockbuster bomb|{{cvt|4000|lb}} "cookie"]]]]
[[File:Lancaster Bomber At The Main Gate, RAF Scampton - geograph.org.uk - 198631.jpg|thumb|[[Tallboy (bomb)|Tallboy]] bombs displayed with a standard ''R5868'' Lancaster at [[RAF Scampton]].]]

{| class="wikitable"
!Codename!!Type of raid or target!!Bomb load
|-
|"Arson"||incendiary area bombing ||14 SBC, each with 236 x {{cvt|4|lb}} Incendiary and Explosive Incendiary bomblets, total 3,304.
|-
|"Abnormal"||factories, railway yards, dockyards||14 x {{cvt|1000|lb}} [[General-purpose bomb|GP/HE bombs]] using both impact and long delay (up to 144 hours) fuses.
|-
|"Cookie"—or—"Plumduff"||Blast, demolition and fire||1 x [[Blockbuster bomb|{{cvt|4000|lb}} impact-fused HC bomb]]. 3 x {{cvt|1000|lb}} GP/HE bombs, and up to 6 SBCs with 1,416 incendiary bomblets.
|-
|"Gardening"||Mining of ports, canals, rivers and seaways||6 x {{cvt|1850|lb}} parachute mines.
|-
|"No-Ball"||[[V-1 flying bomb|V-1 flying bomb launch sites]]||1 x {{cvt|4000|lb}} impact fused HC and up to 18 x {{cvt|500|lb}} GP bombs, with both impact and delay fusing.
|-
|"Piece"||Docks, fortifications and ships||6 x {{cvt|2000|lb}} short-delay fused AP bombs, plus other GP/HE bombs based on local needs or availability.
|-
|"Plumduff-Plus"||Heavy industry||1 x {{cvt|8000|lb}} impact or barometric fused HC and up to 6 x {{cvt|500|lb}} impact or delay fused GP/HE bombs.
|-
|"Usual"||Blast and incendiary area bombing||1 x {{cvt|4000|lb}} impact-fused HC bomb, and 12 SBCs with a total of 2,832 incendiary bomblets.
|-
|no code name given||Medium-range low altitude tactical raids||6 x {{cvt|1000|lb}} short and long delay fused GP/HE bombs, additional {{cvt|250|lb}} GP/HE bombs sometimes added.
|-
|no code name given||Submarines|| (up to 1942): 5 x {{cvt|250|lb}} short-delay fuse SAP bombs for surfaced [[U-boat]]s; (post-1942): 6 x {{cvt|500|lb}} and 3 x {{cvt|250|lb}} anti-submarine depth charge bombs.
|}
[[File:Royal Air Force Bomber Command, 1942-1945. CH15375.jpg|thumb|A 617 Squadron Lancaster dropping a Grand Slam bomb on the [[Arnsberg]] viaduct, March 1945.]]
[[File:Bremen-Farge, Royal Air Force Bomber Command, 1942-1945 CL2607.jpg|thumb|An RAF officer inspects the hole left by a Grand Slam in the reinforced concrete roof of the [[Valentin submarine pens|Valentin submarine factory]] in [[Bremen]], Germany]]
{|class="wikitable"
! Special-purpose weapons and codenames!!Type of target!!Weapon
|-
|"Upkeep"||Dams||1 x {{cvt|9250|lb}}, hydrostatic-fused "Upkeep" mine.
|-
|"Tallboy"||Very strong or durable structures (e.g.: submarine pens); battleship [[German battleship Tirpitz|Tirpitz]]||1 x {{cvt|12000|lb}} short-delay fused "Tallboy" bomb.
|-
|"Grand Slam"||As well as direct hits on very strong or durable targets (such as submarine pens) it could be used indirectly to create a [[camouflet]] (cavern) that undermined structures such as bridges, viaducts and bunkers causing them to collapse.||1 x {{cvt|22000|lb}} short-delay fused "Grand Slam" bomb.
|}
{{clear left}}

=====Bombsights=====
Bombsights used on Lancasters included:<ref>{{citation |last=Black |first=Henry |url=http://lancaster-archive.com/bc-bombsights.html |archive-url=https://web.archive.org/web/20071020002531/http://lancaster-archive.com/bc-bombsights.html |archive-date=2007-10-20 |title=Bombsights |work=lancaster-archive.com |date=2001 |accessdate=14 November 2010}}</ref>
;Mark IX [[Course Setting Bomb Sight]] (CSBS).
:This was an early preset vector bombsight that involved squinting through wires that had to be manually set based on aircraft speed, altitude and bombload. This sight lacked tactical flexibility as it had to be manually adjusted if any of the parameters changed and was soon changed in favour of more advanced designs.
;[[Mark XIV bomb sight|Mark XIV bombsight]]
:A vector bombsight where the bomb aimer input details of the bombload, target altitude and wind direction and the analogue computer then continuously calculated the trajectory of the bombs and projected an inverted sword shape onto a sighting glass on the sighting head. Assuming the sight was set correctly when the target was in the crosshairs of the sword shape, the bomb aimer would be able to accurately release the bombs.
;T1 bombsight
:A Mark XIV bombsight modified for mass production and produced in the USA. Some of the pneumatic gyro drives on the Mk XIV sight were replaced with electronic gyros and other minor modifications were made.
;[[Stabilizing Automatic Bomb Sight]]
:Also known as "SABS", this was an advanced bombsight mainly used by 617 Squadron for precision raids. Like the American [[Norden bombsight]] it was a tachometric sight.

===Radio, radar and countermeasures equipment===
The Lancaster had a very advanced communications system for its time. Most British-built Lancasters were fitted with the [[R1155]] receiver and T1154 transmitter, whereas the Canadian-built aircraft and those built for service in the Far East had American radios. These provided radio direction-finding, as well as voice and [[Morse code|Morse]] capabilities.

; [[H2S radar|H2S]]
: 3 GHz frequency, ground-looking navigation radar system – eventually, it could be homed in on by the German night fighters' [[Naxos radar detector|FuG 350 ''Naxos'']] receiver and had to be used with discretion – a problem which the higher resolution, 10 GHz frequency American [[H2X radar]] never had to deal with. This is the large blister under the rear fuselage on later Lancasters.
; [[H2S (radar)#Fishpond|Fishpond]]
: An add-on to H2S that provided additional (aerial) coverage of the underside of the aircraft to display attacking fighters on an auxiliary screen in the radio operator's position.
; [[Monica radar|Monica]]
: A rearward-looking radar to warn of night fighter approaches. However, it could not distinguish between attacking enemy fighters and nearby friendly bombers and served as a homing beacon for [[Flensburg radar detector|suitably equipped]] German [[night fighter]]s. Once this was realised [[Lichtenstein radar#Allied countermeasures|after mid-July 1944]],<ref>{{cite book |last=Price |first=Alfred |date=1967 |title = Aircraft in Profile No.148 – The Junkers Ju 88 Night Fighters |location=Leatherhead, Surrey UK |publisher=Profile Publications |pages=12–13 }}</ref> it was removed altogether.
; [[GEE (navigation)|GEE]]
: A receiver for a navigation system of synchronised pulses transmitted from the UK – aircraft calculated their position from the time delay between pulses. The range of GEE was {{cvt|300|–|400|mi}}. GEE used a whip aerial mounted on the top of the fuselage ahead of the mid-upper turret.
; Boozer (radar detector)
: A system of lights mounted on the aircraft's instrument panel that lit up when the aircraft was being tracked by the low-[[UHF]] band [[Würzburg radar|''Würzburg-Riese'' ground radar]] and early model [[Lichtenstein radar|Lichtenstein B/C and C-1 airborne radar]]. In practice, it was found to be more disconcerting than useful, as the lights were often triggered by false alerts in the radar-signal-infested skies over Germany.
; [[Oboe (navigation)|Oboe]]
: A very accurate navigation system consisting of a receiver/transponder for two radar stations transmitting from widely separated locations in [[Southern England]] which, when used together, determined the aircraft's position. The system could handle only one aircraft at a time, and was fitted to a [[pathfinder (RAF)|Pathfinder]] aircraft, usually a fast and manoeuvrable [[De Havilland Mosquito|Mosquito]] which marked the target for the main force rather than a Lancaster.
; [[G-H (navigation)|GEE-H]]
: Similar to Oboe but with the transponder on the ground allowing more aircraft to use the system simultaneously. GEE-H aircraft were usually marked with two horizontal yellow stripes on the fins.
; "Village Inn" [[Automatic Gun-Laying Turret]]
: A radar-aimed and ranged gun turret fitted to some Lancaster rear turrets in 1944. Identifiable by a [[radome]] mounted below the turret.
; [[Airborne Cigar]] (ABC)
: This was fitted only to the Lancasters of [[No. 101 Squadron RAF|101 Squadron]]. It had three {{convert|7|ft|m|adj=on}} aerials, two on the top of the fuselage and one under the bomb aimer's position. These aircraft carried a German-speaking crew member and were used to jam ground-to-air communications to German night fighters. The extra equipment and extra crewman added around {{convert|600|lb|kg|0}} to the bomber's weight so the bomb load was reduced by {{convert|1000|lb|kg|0}}.<ref name="Ward2014">{{cite book |first = Chris |last = Ward |title=1 Group Bomber Command: An Operational Record|url= https://books.google.com/books?id=5DkRBQAAQBAJ&pg=PT117 |year=2014 |publisher = Pen and Sword |isbn = 978-1-4738-3810-9 |pages = 117–118 }}</ref> Due to the nature of the equipment, the enemy was able to track the aircraft and 101 Squadron suffered the highest casualty rate of any squadron. Fitted from about mid-1943, they remained until the end of the war.
; [[Tinsel (codename)|Tinsel]]
: A microphone installed in the nacelle of one of the engines that allowed the wireless operator to transmit engine noise on the German night fighter control voice frequencies.

==Operational history==
===Second World War===
[[File:Avro Lancasters flying in loose formation.jpg|thumb|Lancasters of No. 50 Squadron fitted with exhaust shrouds intended to conceal exhaust flames from [[night fighter]]s]]
[[File:Avro Lancaster pigeons WWII IWM TR 193.jpg|thumb|Crewman with [[homing pigeon]]s, 1942. Pigeons were customarily carried aboard Lancasters as a means of communications in the event of a crash, ditching or radio failure.]]

During early 1942, [[No. 44 Squadron RAF|No. 44 Squadron]], based at [[RAF Waddington]], [[Lincolnshire]], became the first RAF squadron to convert to the Lancaster; it was quickly followed by [[No. 97 Squadron RAF|No. 97 Squadron]], which was also based at Waddington.<ref name="goul garb 6" /><ref name = "robertson1964 1415">Robertson 1964, pp. 14–15.</ref> On 2 March 1942, the first operational mission of the Lancaster, deploying naval mines in the vicinity of [[Heligoland Bight]], was performed by aircraft of No. 44 Sqn; a planned mission against the {{ship|German battleship|Tirpitz}} had been rescheduled due to poor weather conditions.<ref name="robertson1964 15">Robertson 1964, p. 15.</ref> On 10 March 1942, the type's first bombing mission was conducted over the German city of [[Essen]], [[North Rhine-Westphalia]].<ref name="goul garb 6 7">Goulding and Garbett 1966, pp. 6–7.</ref>

All Lancasters were temporarily grounded after a crash on 20 March in [[Boston, Lincolnshire]]; this was lifted after each aircraft had been inspected for signs of buckling on the upper wing surface.<ref name="robertson1964 15"/> The first recorded casualties amongst Lancaster crews were recorded on 24 March 1942 with the loss of ''R5493'' to anti-aircraft fire over [[Lorient]].<ref name = "robertson1964 16">Robertson 1964, p. 16.</ref> Due to the high loss rates typically involved in such operations, daytime bombing missions were performed sparingly until the Allies had achieved a level of [[Air supremacy|aerial supremacy]] over the [[Axis powers]].<ref name="goul garb 7"/>

On 17 April 1942, 12 Lancasters of No. 44 and No. 99 Squadrons undertook a bombing raid on the [[MAN SE|Maschinenfabrik Augsburg-Nürnberg A.G., Augsburg]] engine manufacturing plant in Southern Germany; despite flying at low altitude, three bombers were shot down by Luftwaffe Bf 109s over France, and at least two more were lost to anti-aircraft fire at the factory itself. Nonetheless, the factory was successfully bombed, a feat that was personally hailed by Prime Minister [[Winston Churchill]] in the aftermath.<ref name = "robertson1964 1617">Robertson 1964, pp. 16–17.</ref> The attack revealed the existence of the Lancaster to both Germany and the British public alike. On 27 April, an unsuccessful small-scale attack on the ''Tirpitz'' was performed by Lancasters of both No. 44 and No. 99 Squadrons.<ref name = "robertson1964 1718">Robertson 1964, pp. 17–18.</ref>

On the night of 30/31 May 1942, the Lancaster participated in [[Bombing of Cologne in World War II|Operation Millenium]], the first 1,000 bomber raid against the German city of [[Cologne]].<ref name = "robertson1964 19"/> By this point, the number of Lancasters in operational service had surpassed those of the preceding Manchester. On 12 June, the first use of the type by [[RAF Coastal Command]], having loaned aircraft from [[RAF Bomber Command]], commenced; it was used to conduct long range anti-[[U-boat]] operations, reportedly attacking two on 15 June.<ref name = "robertson1964 1920">Robertson 1964, pp. 19–20.</ref>

Additional large-scale raids were performed against [[Emden]] between 19 and 23 June, and against [[Bremen]] between 25 and 29 June, the latter reportedly dealing considerable damage to the [[Focke-Wulf]] aircraft works.<ref name = "robertson1964 1920"/> 40 Lancasters also flew an ineffective long-range raid upon [[Danzig]], arriving after dusk and thus unable to effectively bomb its port to disrupt U-boat construction. On 31 July, 20% of Bomber Command's strength was directed against [[Düsseldorf]], focused on [[Schiess A.G.]]'s machine tool manufacturing plant.<ref name = "robertson1964 20">Robertson 1964, p. 20.</ref> The tempo of Lancaster operations rose to a new height in August 1942, major raids were flown against targets in the [[Ruhr]], [[Duisburg]], and in the [[Baltic Sea]]. An emphasis was placed upon aiding the [[Battle of the Atlantic]] by hindering the [[German Navy]]. Often, when the weather was deemed to be unsuitable for bombing missions, night-time mine-laying operations were flown instead.<ref name = "robertson1964 2021`">Robertson 1964, pp. 20–21.</ref>

A major improvement to night-time bombing came with the implementation of the [[Pathfinder (RAF)|Pathfinder Force]] (PFF) in August 1942, multiple squadrons were transferred from Bomber Command groups to constitute the new unit.{{sfn|Pitchfork|2008|p=254}} These pathfinders were tasked with flying ahead of bomber formations to locate and mark targets using [[Target indicator|Target Indicator]] flares to improve the accuracy of strikes by the following aircraft. Early PFF operations produced mixed results, but did prove decisive on 27/28 August against [[Kassel]] and the three factories of the [[Henschel]] aircraft company in the city.{{sfn|Pitchfork|2008|p=262}}<ref name="RAF">{{cite web |url=http://www.raf.mod.uk/bombercommand/aug42.html |title=Campaign Diary, August 1942 |work=Royal Air Force Bomber Command 60th Anniversary |publisher=[[Royal Air Force]] |date=6 April 2005 |access-date=23 July 2017 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20070611030306/http://www.raf.mod.uk/bombercommand/aug42.html |archive-date=11 June 2007 |df=dmy-all}}</ref> That same night, 12 Lancasters of No. 106 Squadron flew to [[Gdynia]], armed with newly developed anti-[[capital ship]] bombs, intending to hit the battleships [[German battleship Scharnhorst|''Scharnhorst'']] and ''[[German battleship Gneisenau|Gneisenau]],'' as well as the [[aircraft carrier]] [[German aircraft carrier Graf Zeppelin|''Graf Zeppelin'']], but did not manage to hit any ships due to a persistent haze.<ref name = "robertson1964 21">Robertson 1964, p. 21.</ref>

While the Lancaster had been designed to conduct night-time operations, daylight raids were occasionally performed by the type as well.<ref name="goul garb 7">Goulding and Garbett 1966, p. 7.</ref> Occasionally, lone Lancasters would be dispatched to perform decoy raids on key manufacturing sites, such as munitions factories, with the intention of being spotted to cause workers to go to air raid shelters, thus disrupting production.<ref name = "robertson1964 20"/> On 17 October 1942, an audacious daytime raid was performed by 90 Lancasters of [[No. 5 Group RAF|No. 5 Group]], the bombing of the [[Schneider Kreuznach|Schneider Works]] at [[Le Creusot]], France; only a single aircraft, ''W4774'', was lost during the course of the mission.<ref name="goul garb 7"/> Losses were avoided by measures such as flying beneath German radar cover, aerial reconnaissance along the intended route, and the strict observation of secrecy.<ref name = "robertson1964 2122">Robertson 1964, pp. 21–22.</ref>

In late October 1942, the first Lancaster bombing missions over Italy were performed; on 22 and 23, the cities of [[Genoa]] and [[Turin]] were struck at night-time.<ref name = "robertson1964 22">Robertson 1964, p. 22.</ref> On 24 October, the Italian city of [[Milan]] was raided by roughly 60 Lancasters during the daytime; railway infrastructure was a priority target for these attacks. These bombers had been escorted across the Channel by Spitfires before breaking formation to individually fly at low altitude to reach and fly over the [[Alps]]; a total of three were reportedly shot down by enemy fighters.<ref name = "robertson1964 2223">Robertson 1964, pp. 22–23.</ref> During November, targets in Italy and Germany were alternatively attacked by Lancasters, striking the city of [[Osnabrück]] multiple times, conducting a heavy raid against Turin, and destroying supplies for the [[Afrika Korps]] in Genoa. Only eight bombing missions were conducted during all of December, the most prominent of which being against Duisburg, due to poor prevailing weather conditions.<ref name = "robertson1964 23">Robertson 1964, p. 23.</ref>

Throughout 1942, the Lancaster remained in relatively short supply; consequently, both training and crew conversion courses typically had to be performed by the squadrons themselves; there were no aircraft furnished with dual controls at this time, and pilots would therefore have to perform their first flight without their instructors being capable of directly acting on the controls themselves.<ref name="goul garb 7" /><ref name = "robertson1964 19">Robertson 1964, p. 19.</ref> Furthermore, each Lancaster had its own ground crew early on; centralised servicing was introduced later.<ref name = "robertson1964 59">Robertson 1964, p. 59.</ref> By the end of the year, a total of 16 operational squadrons had been stood up while around 200 Lancasters were under Bomber Command.<ref name = "robertson1964 23"/>

On 16 January 1943, the German capital city of [[Berlin]] was raided for the first time in over a year; conducted by an all-Lancaster force, the Berlin raid was fairly inconsequential beyond its psychological impact, not causing meaningful damage to either side.<ref name = "robertson1964 26">Robertson 1964, p. 26.</ref> The first [[radial engine]]d Lancasters were also introduced to service during January, alongside some new bombing aids. On 4 February, 198 Lancasters raided the city of Turin; days later, 466 Lancasters attacked Lorient, and an all-Lancaster force of 142 aircraft attacked Milan on 14 February.<ref name = "robertson1964 2627">Robertson 1964, pp. 26–27.</ref> On 28 February, 86 Lancasters attacked the occupied French city of [[Saint-Nazaire]]; the next day, 79 Lancasters bombed Berlin. On 5 March, the [[Battle of the Ruhr]] strategic bombing campaign was launched by Bomber Command. The initial attack on Essen comprised 412 bombers, 140 of which were Lancasters. In order to cope with the higher attrition rate from these operations, a three-fold increase in production was enacted.<ref name = "robertson1964 2728">Robertson 1964, pp. 27-28.</ref>

On 15 April, Stuttgart was raided by a large force of Lancasters; on the following day, [[Plzeň]] was similarly struck, although much of the intended attack upon the [[Škoda Works]] was unintentionally directed towards a large asylum instead; other targets that month included Stettin, Duisburg, and the Ruhr. The majority of strategic bombing missions flown during May were also directed towards the Ruhr region.<ref name = "robertson1964 29">Robertson 1964, p. 29.</ref>

Perhaps the most famous single mission performed by the Lancaster was flown on 16–17 May 1943, codenamed [[Operation Chastise]], to destroy the dams of the [[Ruhr Area|Ruhr Valley]].<ref name = "robertson1964 2932">Robertson 1964, pp. 29–32.</ref> The operation was carried out by [[No. 617 Squadron RAF|No. 617 Squadron]], which had been formed less than two months prior. They flew modified Lancaster Mk IIIs that were armed with special drum-shaped [[bouncing bomb]]s; these had been specially designed by the British engineer [[Barnes Wallis]]; the Lancaster was the only bomber at the time capable of bearing the weapon.<ref name = "robertson1964 30"/> A total of 19 aircraft were dispatched on the operation, setting off in the evening and flying at very low altitudes most of the way to avoid detection. Initial attacks targeted the [[Mohne Dam]] until it was breached, then moved on to the [[Eder Dam]], and then the [[Sorpe Dam]] and [[Ennepe Dam]].<ref name = "robertson1964 3132">Robertson 1964, pp. 31–32.</ref> The story of the operation was later made into [[The Dam Busters (book)|a book]], and subsequently a film, ''[[The Dam Busters (movie)|The Dam Busters]]''.<ref name = "robertson1964 30">Robertson 1964, p. 30.</ref>

The Ruhr continued to be intensely raided by Bomber Command for months following Operation Chastise with the aim of suppressing the region's industrial output.<ref name = "robertson1964 34">Robertson 1964, p. 34.</ref> In June, Lancasters begun operating in [[North Africa]] using the tactic of [[shuttle bombing]] from airfields in [[Blida]] and [[Dar El Beïda|Maison Blanche]]. This was a key element of [[Operation Bellicose]], the bombing of a German [[radar]] factory in the former [[Luftschiffbau Zeppelin|Zeppelin Works]] at [[Friedrichshafen]] and the Italian naval base at [[La Spezia]].<ref name = "robertson1964 34"/> On 12 July, an all-Lancaster force performed the biggest-yet bombing raid on Turin in support of the recently launched [[Italian campaign (World War II)|Italian Campaign]]. Further missions across the country were flown throughout this month, often focusing on electrical and railway infrastructure.<ref name = "robertson1964 35">Robertson 1964, p. 35.</ref>

[[File:Lancaster over Hamburg.jpg|thumb|A Lancaster over Hamburg, circa 1943]]
During late July and early August 1943, large numbers of Lancasters participated in the devastating round-the-clock raids on the city of [[Hamburg]] during Air Chief Marshal Harris's [[Bombing of Hamburg in World War II|Operation Gomorrah]].<ref name = "robertson1964 3536">Robertson 1964, pp. 35–36.</ref> On the night of 27 July, 787 RAF aircraft, comprising 74 [[Vickers Wellington]]s, 116 [[Short Stirling]]s, 244 [[Handley Page Halifax]]es and 353 Avro Lancasters, bombed the city.{{sfn|Bahnsen|Stürmer|p=41}}<ref>{{Citation |author=RAF staff |date=6 April 2005 |url=http://www.raf.mod.uk/bombercommand/diary.html |title=Bomber Command: Campaign Diary |work=RAF Bomber Command 60th Anniversary|archive-url=http://webarchive.nationalarchives.gov.uk/20070706011932/http://www.raf.mod.uk/bombercommand/diary.html |archive-date=6 July 2007}}</ref> An estimated 18,474 people died on this night alone, despite many of victims being within [[air raid shelter]]s and cellars, as the widespread fires across the city led to [[carbon monoxide]] poisoning.{{sfn|Overy| 2013|p=334}} Altogether, 8,621 tons of bombs were dropped on Hamburg by the end of the operation.<ref name = "robertson1964 36">Robertson 1964, p. 36.</ref>

On the night of 17/18 August, [[Operation Hydra (1943)|Operation Hydra]] was conducted against the [[Peenemünde Army Research Center]], the site of the [[V-2 rocket]] and other [[List of German guided weapons of World War II|German guided missiles and munitions]]; 17 Lancasters were lost in the costly but successful attack, mainly to German night fighters.<ref name = "robertson1964 37"/><ref>Richards 2001, p. 200.</ref> Five days later, Lancasters struck numerous [[chemical works]] across Germany, including those in Leverkusen and Düsseldorf. On 23 August, a major raid on Berlin was conducted, dropping roughly 1,700 tons of bombs on the city; German night fighters responded, causing a 5.4% loss rate amongst Lancasters, while the Halifax and Stirling bombers suffered 8.8% and 12.9% loss rates respectively. Numerous strikes on the German capital occurred over the following weeks, sometimes by an all-Lancaster force.<ref name = "robertson1964 37">Robertson 1964, p. 37.</ref>

In September, Hanover was subjected to the most concentrated bombing raid of the war so far.<ref name = "robertson1964 38">Robertson 1964, p. 38.</ref> In October, the widespread bombing of numerous German cities took place, targeting Munich, Kassel, Frankfurt, Offenbach, Ludwigshafen, Stuttgart, Friedrichshafen, and Leipzig, along with other targets. By this point, the [[Royal Canadian Air Force]] had stood up its own operational squadrons equipped with Lancasters, and proceeded with offensive action over Germany in this same month.<ref name = "robertson1964 3839">Robertson 1964, pp. 38–39.</ref>

In late 1943, Air Chief Marshal Harris advocated to Churchill for the persistent bombing of Berlin in preference to earlier targets such as the Ruhr.<ref name = "robertson1964 3950">Robertson 1964, pp. 39, 50.</ref> Between 15 November 1943 and 24 November 1944, sixteen major bombing operations were conducted against the German capital in the [[Battle of Berlin (RAF campaign)|Battle of Berlin]]; of the 9,111 sorties flown, 7,256 had been performed by Lancasters. These raids, while often incurring in costly losses, were typically deemed to have been 'most satisfactory' by senior officials.<ref name = "robertson1964 50">Robertson 1964, p. 50.</ref> In March 1944, the Berlin raids were somewhat lessened as a compromise, Bomber Command having been directed to destroy enemy communications and other targets around France and the [[Low Countries]] ahead of the [[Normandy landings]] on [[D-Day (military term)|D-Day]].<ref name = "robertson1964 5054">Robertson 1964, pp. 50–54.</ref>

During April 1944, key targets in France included railway hubs in Villeneuve, [[Rouen]], and [[Juvisy]].<ref name = "robertson1964 5354">Robertson 1964, pp. 53–54.</ref> Special operations were flown against specific ammunition depots, munitions factories, and coastal batteries in advance of the Allied invasion. Around this time, Lancasters would also provide direct support to the local operations of field forces.<ref name = "robertson1964 54">Robertson 1964, p. 54.</ref> By May, Bomber Command had a daily average operating strength of roughly 1,100 aircraft, 616 of which were Lancasters, 354 were Halifaxes, 72 Mosquitos, and 58 Stirlings; between 300 and 400 bombers were being deployed every night, dependent on weather conditions.<ref name = "robertson1964 63">Robertson 1964, p. 63.</ref> In May and June, extensive operations were flown against the fortifications of the [[Atlantic Wall]]. The first combat use of Barnes Wallis' {{cvt|12000|lb}} [[Tallboy (bomb)|'Tallboy' bombs]] occurred around this time.<ref name = "robertson1964 64">Robertson 1964, p. 64.</ref>{{sfn|Collier|1976|pp=68, 84}}

On 14 June, the first large-scale daylight bombing raid since 1942 was conducted using Lancasters against enemy shipping at the harbours of [[Le Havre]] and [[Boulogne]].<ref name = "robertson1964 65">Robertson 1964, p. 65.</ref> These daylight raids quickly became frequent as, due to a shortage of [[oil]], the Luftwaffe were increasingly incapable of mounting opposition; to further this difficulty for their opponent, Lancasters were directed against numerous oil installations. In conjunction, low-level nighttime bombing raids continued, but the emphasis shifted away from the strategic bombing of German industry in favour of directly attacking military concentrations, such as U-boat pens and [[V-1 flying bomb]] launch sites.<ref name = "robertson1964 6566">Robertson 1964, pp. 65–66.</ref>

During July, in the days following the Normandy landings, Lancasters heavily bombed the city of [[Caen]] repeatedly.<ref name="robertson1964 66">Robertson 1964, p. 66.</ref> On 24 August, eight Tallboys were dropped in a daylight attack on the U-boat pens at [[IJmuiden]], two direct hits were recorded. Multiple raids on V-1 launch sites and enemy shipping were also performed during August; the partially constructed battleship [[Richelieu-class battleship#Clemenceau and Gascogne|''Clemenceau'']] was one of the targets that were struck around this time.<ref name = "robertson1964 6667">Robertson 1964, pp. 66–67.</ref> September saw a heavy focus on airfields in [[Holland]], as well as repeated raids on German-held [[Le Havre]] and oil targets in the Ruhr. On 17 September, precision strikes were performed on [[Boulogne]] only 200 yards from the Allied lines.<ref name="robertson1964 66"/>

In October, Lancasters repeatedly struck the sea wall at [[Westkapelle, Netherlands|Westkapelle]], seeing to prevent the Germans from intentionally flooding neighbouring lands to delay Allied ground forces.<ref name = "robertson1964 68">Robertson 1964, p. 68.</ref> Extensive daylight raids were performed during the month; cities such as Cologne, Walcheren, and Bergen were targeted by hundreds of Lancasters. Bomber operations proceeded in both day and nighttime against industrial towns, airfields, communications, and troop concentrations into December; one such operation was flown against the [[E-boat]] pens at [[Rotterdam]] on 29 December.<ref name = "robertson1964 6970">Robertson 1964, pp. 69–70.</ref>

Throughout the latter half of 1944, a series of high-profile bombing missions were performed by the Lancaster against the {{ship|German battleship|Tirpitz}}.<ref name="goul garb 7 10">Goulding and Garbett 1966, pp. 7, 10.</ref><ref name = "robertson1964 74">Robertson 1964, p. 74.</ref> Executed by Nos. 617 and 9 Sqns, a combination of Lancaster B.I and B.III bombers were armed with Tallboy bombs and were adapted with enlarged bomb bay doors in order to accommodate their special payloads and additional fuel tanks to provide the necessary endurance. A total of three attacks, individually codenamed [[Operation Paravane]], [[Operation Obviate]] and [[Operation Catechism]], were conducted against ''Tirpitz'', which was anchored in a [[fjord]] in [[German occupation of Norway|Occupied Norway]].<ref name="goul garb 7 10" /> The first of these attacks disabled the vessel while the third mission was responsible for sinking the ship. Due to actions such as Operation Chastise and the sinking of ''Tirpitz'', [[No. 617 Squadron RAF|No. 617 Sqn]] was perhaps the most famous of all Lancaster squadrons.<ref name="goul garb 7" /><ref name = "robertson1964 7577">Robertson 1964, pp. 75–77.</ref>

On 1 January 1945, the [[Dortmund–Ems Canal]] was attacked by Lancasters, hitting it at a vulnerable section near Ladbergen.<ref name = "robertson1964 82">Robertson 1964, p. 82.</ref> An attack on [[Pforzheim]] on 23 February was described by aviation author Bruce Robertson as amongst the most concentrated and successful flown in the conflict. In the final months of the war, Lancasters were encountering the newly developed [[Messerschmitt Me 262]], the first German [[jet propulsion|jet-powered]] fighter aircraft, sometimes flying in formations of up to 40 aircraft.<ref name = "robertson1964 8384">Robertson 1964, pp. 83–84.</ref> On 4 November 1944, a Lancaster of 428 squadron was attacked by a Me 262, which was shot down by the rear gunner Ben Rakus. The pilot F.W. Walker noted that this was the first instance of a heavy bomber shooting down a jet.<ref name = "McKinstry 2009 425">McKinstry 2009, p. 425.</ref> 

During early 1945, a total of 33 Lancaster B.Is were modified so that they could deploy the {{cvt|22000|lb}} [[Grand Slam (bomb)|Grand Slam bomb]], the heaviest conventional bomb to be used during the conflict.<ref name="goul garb 10">Goulding and Garbett 1966, p. 10.</ref>{{sfn|Flower|2013|pp=355–356}} On 13 March 1945, the first operational use of the Grand Slam was performed by a Lancaster of No. 617 Sqn against the [[Hamm–Minden railway#Schildesche viaduct|Bielefeld viaduct]] in [[North Rhine-Westphalia]]; this target had not yet been rendered inoperable despite being damaged by prior conventional bombing. The Tallboy strike successfully destroyed roughly 100 yards of the viaduct's length; additional viaducts, such as at Arnsberg, were promptly targeted by the squadron thereafter.<ref name = "robertson1964 84">Robertson 1964, p. 84.</ref>

By April 1945, there were in excess of 1,000 Lancasters in frontline service, dwarfing the numbers of Halifaxes and [[de Havilland Mosquito|Mosquitos]] (a [[light bomber]]) operated by Bomber Command at that time.<ref name = "robertson1964 85">Robertson 1964, p. 85.</ref> Key industrial sites, such as the [[Auguste Viktoria]] [[Benzole|benzol]] factory, were struck, while oil installations continued to be a prominent target of bombing raids in the hope of exacerbating the German fuel shortage. Amongst the final wartime operations performed by the Lancaster was the [[Bombing of Obersalzberg]], aimed at the destruction of [[Kehlsteinhaus|''Eagle's Nest'']], the extensive holiday home complex used by German leader [[Adolf Hitler]].<ref name="goul garb 10" />{{sfn|Haller|2011|p=12}} Unusually, the [[BBC]] were permitted to announce the raid before it was completed.<ref name = "robertson1964 8586">Robertson 1964, pp. 85–86.</ref>

[[File:The Royal Air Force during the Second World War CH13151.jpg|thumb|A Lancaster being fuelled from an [[AEC Matador]] truck, 1944]]

RAF Lancasters dropped food into the Holland region of the occupied Netherlands, with the acquiescence of the occupying [[German Army (Wehrmacht)|German forces]], to feed people who were in danger of starvation.<ref name="goul garb 10" /><ref name = "robertson1964 8687">Robertson 1964, pp. 86–87.</ref> The mission was named '[[Operations Manna and Chowhound|Operation Manna]]' after the food [[manna]] which is said to have miraculously appeared for the [[Israelite]]s in the [[Book of Exodus]]. The aircraft involved were from 1, 3, and 8 Groups, and consisted of 145 [[de Havilland Mosquito|Mosquitos]] and 3,156 Lancasters, flying between them a total of 3,298 [[sortie]]s. The first of the two RAF Lancasters chosen for the test flight was nicknamed "[[Bad Penny (aircraft)|Bad Penny]]" from the old expression: "a bad penny always turns up." This bomber, with a crew of seven men (five Canadians including pilot Robert Upcott of [[Windsor, Ontario]]), took off in bad weather on the morning of 29 April 1945 without a ceasefire agreement from the German forces, and successfully dropped its cargo.{{citation needed|date=March 2018}}

====Assessment====
The Lancaster conducted a total of 156,000 sorties and dropped {{cvt|608612|LT|kg}} of [[bomb]]s between 1942 and 1945. Only 35 Lancasters completed more than 100 successful operations each, and 3,249 were lost in action. The most successful survivor completed 139 operations and was ultimately retired from service and scrapped in 1947. From 1942 onwards, the Lancaster became the mainstay of the British heavy bomber fleet; by the end of the war in Europe, there were roughly 50 squadrons equipped with the Lancaster, the majority of these being the Lancaster B.I model.<ref name="goul garb 7" /> From its entry into service, the original model of the Lancaster was operated in almost every major bombing raid of the European conflict.<ref name="goul garb 11" />

[[Adolf Galland]] (commander of the Luftwaffe fighters) considered the Lancaster to be "the best night bomber of the war",<ref>Galland 2005, p. 119.</ref> as did his adversary, [[Arthur Harris|Arthur "Bomber" Harris]], who referred to it as Bomber Command's "shining sword".<ref>Iveson 2009, p. 82.</ref> Goulding and Garbett wrote that: "The achievements of the Lancaster and the men who flew it have been widely acclaimed, and the aircraft has been described as the greatest single factor in winning WWII, an exaggeration but a pardonable one".<ref name="goul garb 6"/>

Lancasters from Bomber Command were to have formed the main strength of [[Tiger Force (air)|Tiger Force]], the Commonwealth bomber contingent scheduled to take part in [[Operation Downfall]], the codename for the planned invasion of Japan in late 1945.<ref name="goul garb 11"/> Aircraft allocated to the Tiger Force were painted in white with black undersides and outfitted with additional radio units and navigational aids to facilitate their use in the [[Pacific Ocean theater of World War II|Pacific theatre]]. The addition of large saddle-type external fuel tanks was considered and trialled in Australia and India, but this was discontinued due to their perceived vulnerability to attack.<ref name="goul garb 11 12">Goulding and Garbett 1966, pp. 11–12.</ref> Together with the new [[Avro Lincoln]] and Liberators, the bombers would have operated from bases on [[Okinawa Prefecture|Okinawa]]; the envisioned invasion did not happen when such action was made unnecessary by the [[surrender of Japan]].<ref name="goul garb 11"/>

While the Lancaster was briefly considered for carrying the atomic bomb as being one of the two Allied bombers capable of carrying the atomic bomb internally, after the [[Boeing B-29 Superfortress]] began to be modified in November 1943  for carrying the new bombs,  the suggestion for using the Lancaster never came up again.<ref>"Lancaster: The Second World War's Greatest Bomber", Leo McKinstry p. 495</ref>  Using the Lancaster would have required less modification to the aircraft itself, but would have necessitated additional crew training for the USAAF crews. In addition, the Lancaster had  a lower ceiling and flew slower so was at risk of the bomb blast. It also had a shorter range. "The B-29 was, therefore, deemed the better bet if it could be modified in time.".<ref>{{cite web | url=https://interestingengineering.com/innovation/first-atomic-bombs-black-lancasters | title=Black Lancasters: The story of heavy British bomber and first atomic bombs | date=22 February 2023 }}</ref>  [[Major general (United States)|Major General]] [[Leslie Groves]], the director of the [[Manhattan Project]], and [[General (United States)|General]] [[Henry H. Arnold]], the Chief of [[United States Army Air Forces]] (USAAF), wished to use an American plane if this was at all possible. "Because the use of a British plane would have caused us many difficulties and delays"<ref>{{cite book |last=Groves |first=Leslie |author-link=Leslie Groves |title=Now it Can be Told: The Story of the Manhattan Project |location=New York |publisher=Harper & Row |year=1962 |isbn=0-306-70738-1 |oclc=537684 |pages=254–255}}</ref>

As a byproduct of its sound design and operational success, various developments and derivatives of the Lancaster were produced for both military and civilian purposes. One of these was the [[Avro Lincoln]] bomber, initially designated Lancaster IV and Lancaster V which became the Lincoln B.1 and B.2 respectively. A civilian airliner was converted from the Lancaster with the addition of nose and tail fairings and seats, as the [[Avro Lancastrian|Lancastrian]] and a similar aircraft was derived from the Lincoln as the [[Avro Lincolnian|Lincolnian]]. Other developments included the [[Avro York|York]], a transport with a much larger square section fuselage, and via the Lincoln, the [[Avro Shackleton|Shackleton]] maritime patrol aircraft which continued in RAF service in that role until replaced by the [[Hawker Siddeley Nimrod]] in the early 1970s, but saw further service as an [[airborne early warning]] (AEW) system until finally retired in 1991. The [[Avro Tudor|Tudor]] airliner also used the Lincoln wings, but with a new tubular fuselage.

===After the war===
====Royal Air Force====
The Lancaster remained in use for several years after the end of the war, during which a number of high-profile operations were conducted.<ref name="goul garb 12"/>

During the summer of 1946, [[No. 35 Squadron RAF|No. 35 Squadron]] Lancasters toured the United States and were [[autograph]]ed by various American movie stars, and retained these until their retirements.<ref name="goul garb 12"/> A pair of Lancasters, ''PD328'' and ''PB873'', performed several long-distance flights, including round-the-world and trans-polar trips.<ref name="goul garb 12">Goulding and Garbett 1966, p. 12.</ref>

The Lancaster remained at the forefront of RAF Bomber Command while the Lancaster B.I was gradually replaced by the improved Lancaster B.I (F/E) and B.VII (F/E) models.<ref name="goul garb 11"/> During 1947–1948, [[No. 82 Squadron RAF|No. 82 Squadron]] received new PR.1 dedicated photo-reconnaissance model derived from the Lancaster B.1 which was painted silver and lacked defensive turrets. These carried out aerial surveys of Central and [[East Africa]] and at least one was operated by the [[Ministry of Aviation]].<ref name="goul garb 12" /> [[RAF Coastal Command]] received a small number of grey-painted Lancaster MR.1s, which were normally based at [[RAF Kinloss]], [[Moray Firth]].<ref name="goul garb 12" />

The Lancaster continued to be operated in significant numbers until the introduction of the [[Avro Lincoln]], a development of the Lancaster. The Lincoln was not available in quantity for several years following the end of the conflict,<ref name = "mat kit gra 59 60">Mantelli, Brown, Kittel and Graf 2017, pp. 59–60.</ref> and it took until December 1953 for the final Bomber Command Lancaster to be retired.<ref name="goul garb 11"/> The last Lancaster in active service with the RAF, a reconnaissance aircraft, is believed to have been retired in late 1954.<ref name="goul garb 12 13">Goulding and Garbett 1966, pp. 12–13.</ref>

====French Aéronavale====
Avro overhauled 59 Lancaster B.Is and B.VIIs at Woodford and Langar which were delivered to the French ''[[Aéronavale]]'' during 1952/53,<ref name="goul garb 14">Goulding and Garbett 1966, p. 14.</ref> which were flown until the mid-1960s by four squadrons stationed in France and [[New Caledonia]] in the maritime reconnaissance and search-and-rescue roles.<ref>Jackson 1990, p. 365.</ref>

====Argentine Air Force====
Between 1948 and 1949, 15 former RAF Lancasters were overhauled at Langar for use by the [[Argentine Air Force]].<ref name="goul garb 14"/> During its Argentine service, Lancasters were used offensively in suppressing and supporting military [[coup d'état|coups]].<ref>{{cite book |last1=Mantelli, Brown, Kittel, Graft |title=Avro Lancaster-Handley Page Halifax-Short S.29 Stirling |date=2017 |publisher=Edizioni R.E.I |location=Italy |isbn=978-2-37297-333-5 |page=60 |edition=first |url=https://books.google.com/books?id=EuFKDgAAQBAJ&pg=PA60}}</ref>

====Royal Canadian Air Force====
[[File:Lancaster10MP 405Sqn RCAF NAS Jax Feb1953.jpg|thumb|RCAF 405 Squadron Lancaster 10MP Maritime Patrol aircraft in February 1953]]
Beginning in 1946, Lancaster Mk Xs were modified for service with the [[Royal Canadian Air Force]] (RCAF). Fourteen were modified to perform aerial and photo-reconnaissance missions; these would go on to perform much of the mapping of northern Canada until as late as 1962. Throughout the 1950s, the RCAF operated seventy modified Lancasters, designated ''Lancaster 10MR/MPs'', as Maritime Reconnaissance and Patrol aircraft in an anti-submarine role. Modifications involved the installation of radar and sonobuoy operators' positions, removal of the rear and mid-upper gun turrets, installation of a 400-gallon fuel tank in the bomb bay to increase the patrol range, upgraded electronics, radar, and instrumentation, and a cooking stove in the centre section.<ref>[http://www.aviation.technomuses.ca/collections/artifacts/aircraft/AvroLancasterX/ "Lancaster X."] {{webarchive |url=https://web.archive.org/web/20110830103603/http://www.aviation.technomuses.ca/collections/artifacts/aircraft/AvroLancasterX/ |date=30 August 2011}} ''Canadian Aviation and Space Museum.'' Retrieved 3 October 2011.</ref> They served throughout the 1950s, when they were supplemented by the [[Lockheed Neptune]] and finally replaced by the [[Canadair Argus]].<ref name="Bomber Command Museum">[http://www.bombercommandmuseum.ca/lanccanadian.html "The Canadian Lancasters."] {{webarchive |url=https://web.archive.org/web/20161030014404/http://www.bombercommandmuseum.ca/lanccanadian.html |date=30 October 2016}} ''Bomber Command Museum.'' Retrieved 3 October 2011.</ref>

====Transport====
Immediately following the end of hostilities, the Lancaster was used without any major modifications as a transport aircraft, being used to ferry thousands of [[prisoner of war|prisoners of war]] (POWs) back to the British Isles from across the continent.<ref name="goul garb 10 11">Goulding and Garbett 1966, pp. 10–11.</ref> Repatriation flights returning POWs and ordinary troops continued until November 1945.<ref name="goul garb 11">Goulding and Garbett 1966, p. 11.</ref>

Civil conversions of the type continued during the initial postwar years. In 1946, four Lancasters were converted by Avro at [[Bracebridge Heath]], [[Lincolnshire]] as freighters for use by [[British South American Airways]], but proved to be uneconomical, and were withdrawn after a year in service. In addition, four Lancaster IIIs were converted by [[Cobham plc|Flight Refuelling Limited]] as two pairs of tanker and receiver aircraft for the development of [[Aerial refueling|in-flight refuelling]]. In 1947, one aircraft was flown non-stop {{cvt|3459|mi}} from London to Bermuda. Later on, these two tanker aircraft were joined by another converted Lancaster; these saw use during the [[Berlin Airlift]], achieving 757 tanker sorties.{{citation needed|date=April 2017}}

From 1943 to 1947, the Canadian Government Trans-Atlantic Air Service (CGTAS) provided a trans-Atlantic military passenger and postal delivery service using a modified long-distance transport version of the Lancaster Mark X. Nine of these aircraft were produced, referred to as Lancaster XPPs (for Lancaster Mk.X Passenger Planes), and each was equipped with rudimentary passenger facilities. The inaugural flight from Dorval (Montreal) to Prestwick, Scotland on 22 July 1943, was completed non-stop in a record 12:26 hours; the average crossing time was about 13:25 hours. By the end of the war, these aircraft had completed hundreds of trips across the Atlantic. CGTAS ushered in the era of commercial air travel across the North Atlantic, and in 1947 the service became part of [[Trans-Canada Air Lines]], which carried paying civilian passengers in the Lancaster XPPs until they were replaced by [[Douglas DC-4]]s in 1947.<ref name="Bomber Command Museum"/><ref>[http://www.cahf.ca/members/T_members.php "Members' Profiles."] {{webarchive |url=https://web.archive.org/web/20110813085734/http://www.cahf.ca/members/T_members.php |date=13 August 2011}} ''Canada's Aviation Hall of Fame.'' Retrieved 3 October 2011.</ref><ref>[http://www.bombercommandmuseum.ca/lancafterwar.html "Lancasters After The War."] {{webarchive |url=https://web.archive.org/web/20110826121947/http://www.bombercommandmuseum.ca/lancafterwar.html |date=26 August 2011}} ''Bomber Command Museum.'' Retrieved 3 October 2011.</ref>

==Variants==
; {{visible anchor|B.I}}
: The original Lancasters were produced with [[Rolls-Royce Merlin|Rolls-Royce Merlin XX]] engines and [[SU carburetor|SU]] [[carburettors]]. Minor details were changed throughout the production series – for example, the [[Pitot tube|pitot]] head design was changed from being on a long mast at the front of the nose to a short fairing mounted on the side of the fuselage under the cockpit. Later production Lancasters had Merlin 22 and 24 engines.<ref name="BAE Systems Avro Lancaster" /> No designation change was made to denote these alterations.<ref>Franks 2000, pp. 83–84.</ref>

; B.I Special
[[File:Avro Lancaster B Mk I (Special) of No. 617 Squadron, loaded with a 'Grand Slam' 22,000-lb deep-penetration bomb, running up its engines at Woodhall Spa, Lincolnshire, 1944. MH4263.jpg|thumb|B.I Special loaded with a Grand Slam]]
: 32 Aircraft were adapted to take first the super-heavy "[[Tallboy bomb|Tallboy]]" and then "[[Grand Slam bomb|Grand Slam]]" bombs. Up-rated engines with paddle-bladed propellers gave more power, and the removal of [[gun turret]]s reduced weight and gave smoother lines. For the Tallboy, the bomb bay doors were bulged; for the Grand Slam, they were removed completely and the area faired over. For some Tallboy raids, the mid-upper turret was removed. This modification was retained for the Grand Slam aircraft, and in addition, the nose turret was later removed. Two airframes (''HK541'' and ''SW244'') were modified to carry a dorsal "saddle tank" with {{cvt|1200|impgal}} mounted aft of a modified canopy for increasing range. No. 1577 SD Flight tested the aircraft in [[India]] and [[Australia]] in 1945 for possible use in the Pacific,<ref name="Franks"/> but the tank adversely affected handling characteristics when full and an early type of [[Aerial refuelling|in-flight refuelling]] designed in the late 1930s for commercial flying boats was later used instead.<ref>[https://books.google.com/books?id=KSYDAAAAMBAJ&pg=RA2-PA82 "Flying Gas Station In The Sky".] ''Popular Science'', January 1947.</ref><ref name="BAE Systems Avro Lancaster" />

[[File:Lancasters.jpg|thumb|PR1. 683(PR) Squadron, RAF Fayid, Egypt, undertaking photographic reconnaissance and mapping activities]]
; PR.1
: B 1 modified for photographic reconnaissance, operated by RAF No. 82 and No. 541 Squadrons, wartime. All armament and turrets were removed with a reconfigured nose and a camera carried in the bomb bay. The type was also operated by 683(PR) Squadron when it was re-formed in November 1950 to undertake photographic reconnaissance and mapping activities, initially based at RAF Fayid, Egypt, before moving to RAF Kabrit in February 1951, and subsequently [[RAF Habbaniya|Habbaniya]] in [[Iraq]] until the squadron was disbanded on 30 November 1953.<ref name="BAE Systems Avro Lancaster" />

;B.I (FE)
:In anticipation of the needs of the [[Tiger Force (air)|Tiger Force]] operations against the [[Japan]]ese in the [[Far East]] (FE), a tropicalised variant was based on late production aircraft. The B.I (FE) had modified radio, radar, nav-aids, and a {{cvt|400|impgal}} tank installed in the bomb bay. Most were painted with white upper surfaces to reduce internal temperatures in the tropical sun, and black undersides with a low demarcation between the colours, [[Royal Air Force roundels#SEAC and RAAF|completely omitting any red colours]] on the national insignia in all cases to avoid confusion with the ''[[hinomaru]]'' insignia of the Japanese.<ref name="BAE Systems Avro Lancaster" />

; B.II
[[File:Lancaster B Mark II of 115 Squadron RAF 1943 IWM CH 19792.jpg|thumb|B.II with [[Bristol Hercules]] radial engines]]
: [[Bristol Hercules]] (Hercules VI or XVI engines) powered variant, of which 300 were produced by [[Armstrong Whitworth]]. One difference between the two engine versions was that the VI had manual mixture control, requiring an extra lever on the throttle pedestal. Very early examples were fitted with an FN.64 ventral turret; however, these were quickly removed due to problems with aiming the turret through its periscope (which prevented the gunner from seeing a target he was not already aiming at), and inadequate traverse speed.<ref name="BAE Systems Avro Lancaster" />

:Due to the Luftwaffe ''Schräge Musik'' attacks, a variety of unofficial field modifications were made, including the fitting of {{cvt|20|mm}} cannon or a {{cvt|.50|in}} machine gun in the open hole where the FN.64 had been installed, before an official modification (Mod 925) fitted with a {{cvt|.303|in}} machine gun was authorised for the same location, though not used in all aircraft. These were rarely installed on other variants as the [[H2S radar]] was usually installed, however the B.II's bulged bomb bay interfered with its installation, leaving the opening free. Three types of bulged bomb bay were used on the B.II, the prototype having a narrow bulge running from just aft of the cockpit to the turret location, while early production examples had a full-width bulge that ran the same length and on late production examples, the bomb bay doors prominently bulged throughout their length.<ref name="BAE Systems Avro Lancaster" />

;{{visible anchor|B.III}}
:This variant, which was built concurrently with the B.I and was indistinguishable externally from that variant, was fitted with [[Packard]]-built Merlin engines. The Packard Merlins used [[Bendix Corporation|Bendix – Stromberg]] pressure-injection [[carburettor]]s, requiring the addition of slow-running cut-off switches in the [[cockpit]].<ref name="BAE Systems Avro Lancaster" />

;B.III (Special)
[[File:Upkeep in Lancaster.jpg|thumb|"Upkeep" [[bouncing bomb]] used for dam busting bomb mounted under Lancaster B.III (Special). The chain was driven by a hydraulic motor and gave the bomb its [[backspin]].]]
:Known at the time of modification as the "Type 464 Provisioning"<ref>Avro manufacturing drawing Z2852</ref> Lancaster, 23 aircraft of this type were built to carry the "Upkeep" [[bouncing bomb]] for the dam busting raids. The bomb bay doors were removed and Vickers-built struts to carry the bomb were fitted in their place at Woodford Aerodrome near Stockport where the workers worked day and night. A hydraulic motor, driven by the pump previously used for the mid-upper turret was fitted to spin the bomb. Lamps were fitted in the bomb bay and nose for the simple height measurement system which enabled the accurate control of low-flying altitude at night. The mid-upper turret was removed to save weight and the gunner moved to the front turret to relieve the bomb aimer from having to man the front guns so that he could assist with map reading.<ref name="BAE Systems Avro Lancaster" />

;ASR.III/ASR.3
:B.III modified for [[air-sea rescue]], with three dipole ventral antennas fitted aft of the [[radome]] and carrying an [[airborne lifeboat]] in an adapted bomb bay. The armament was often removed and the mid-upper turret faired-over, especially in postwar use. Observation windows were added to both sides of the rear fuselage, a port window just forward of the tailplane and a starboard window into the rear access door. A number of ASR 3 conversions were fitted with Lincoln-style rudders.<ref name="BAE Systems Avro Lancaster" /><ref>Franks 2000, p. 87.</ref>
[[File:Avro Lancaster.png|thumb|Lancaster B Mk.I drawing with extra side views for the B Mk.I (Special) with ''Grand Slam'' bomb, Hercules-powered B Mk.II with bulged bomb bay doors and FN.64 ventral turret and the B Mk.III (Special) with the ''Upkeep'' store]]

;GR.3/MR.3
:B.III modified for maritime reconnaissance.

;B.IV
:The B.IV featured an increased wingspan and lengthened fuselage and new [[Boulton Paul]] F turret (two X [[Browning M2|0.5in Browning machine guns]]) with framed "bay window" nose glazing. The prototypes (''PW925'', ''PW929'' and ''PW932'') were powered by two-stage Merlin 85s inboard and later, Merlin 68s on the outboard mounts. Because of the major redesign, the aircraft was quickly renamed [[Avro Lincoln|Lincoln B 1]].<ref name="BAE Systems Avro Lancaster" />

;B.V
:Increased wingspan and lengthened fuselage, two-stage Merlin 85s. Renamed [[Avro Lincoln|Lincoln B 2]].<ref name="BAE Systems Avro Lancaster" /><ref name = "mat kit gra 59">Mantelli, Brown, Kittel and Graf 2017, p. 59.</ref>

;B.VI
:Nine aircraft converted from B.IIIs. Fitted with Merlin 85/87 which had two-stage superchargers, giving much improved high-altitude performance. The B VI could achieve a maximum speed of {{cvt|313|mph}} at {{cvt|18200|ft}} at a {{cvt|65000|lb}} takeoff weight and a service ceiling of {{cvt|28500|ft}} at the same weight. Climb to {{cvt|28000|ft}} at {{cvt|65000|lb}} takeoff weight was accomplished in 44.8 minutes with a maximum climb rate of 1,080&nbsp;ft/min (5.5&nbsp;m/s) at {{cvt|1000|ft}}.<ref name="Mason, Tim. 1998, p.302">Mason 1998, p. 302.</ref> A Lancaster B VI was dived to a maximum indicated speed of {{cvt|350|mph}}, or Mach 0.72 at {{cvt|25000|ft}} in June 1944.<ref>Mason 1998, p. 102.</ref> The Merlin 85/87 series engines were fitted with annular cowlings similar to the [[Avro Lincoln]] and three-bladed paddle-type propellers were fitted. These aircraft were used by only [[Pathfinder (RAF)|Pathfinder units]]; by [[No. 7 Squadron RAF]], [[No. 83 Squadron RAF]], [[No. 405 Squadron RCAF]] and by [[No. 635 Squadron RAF]]. Often used as a "Master Bomber" the B VIs were allocated to [[RAF Bomber Command]] apart from two that were retained by [[Rolls-Royce Limited|Rolls-Royce]] for installation and flight testing.<ref>Holmes 2001, p. 39.</ref> Their dorsal and nose turrets were removed and faired over. The more powerful engines proved troublesome in service and were disliked by ground maintenance staff for their rough running and propensity to 'surge and hunt', making synchronisation impossible. This was caused by variations in the fuel/air mixture and over time would damage the engine.<ref>"The Immortal Lanc" 1977, p. 157.</ref> The B VI was withdrawn from operational service in November 1944 and surviving aircraft were used by [[Rolls-Royce Limited|Rolls-Royce]], the [[Royal Aircraft Establishment]] and the Bomb Ballistics Unit (BBU) for various testing and experimental duties.<ref name="BAE Systems Avro Lancaster" />

;B.VII
:The B.VII was the final production version of the Lancaster. The [[Glenn L. Martin Company|Martin]] 250CE mid-upper turret was moved slightly further forward than on previous Marks and the Nash & Thomson FN-82 tail turret with twin {{cvt|0.50|in|1}} Browning machine guns replaced the FN.20 turret with four [[M1919 Browning machine gun#Browning .303 Mark II|Browning .303 Mark IIs]]. The Martin turret carried two 0.5-inch Browning Mark II machine guns which packed much more punch than the .303s of the older turret. However, these Martin turrets arrived too late for inclusion in the first 50 aircraft built by Austin and these were therefore referred to as Mark VII (Interim). Another 180 true Mark VIIs were built at Longbridge. Two sub-variants of the VII existed, the "Far East" (B VII FE) for use in tropical climates and the B VII "[[Western Union (alliance)|Western Union]]", which went to France.<ref name="BAE Systems Avro Lancaster">{{cite web |title=Avro 683 Lancaster: The most iconic heavy bomber of World War II. |url=https://www.baesystems.com/en/heritage/avro-683-lancaster |website=BAE Systems |access-date=12 February 2021 |ref=98 |archive-url=https://web.archive.org/web/20201028081754/https://www.baesystems.com/en/heritage/avro-683-lancaster |archive-date=28 October 2020}}</ref>

;B.X
[[File:Aircrew & Groundcrew of a No. 428 Squadron RCAF, Avro Lancaster.jpg|thumb|Propaganda shot before bombing up an [[No. 428 Squadron RCAF|RCAF 428 Squadron]] B Mk X. This aircraft carries the early "needle-blade" propellers.]]
:The B.X was a Canadian-built B.III with Canadian- and US-made instruments and electrics. In later batches, the heavier Martin 250CE was substituted for the Nash & Thomson FN-50 mid-upper turret, mounted further forward to maintain [[centre of gravity]] balance. Canada was a long-term operator of the Lancaster, using modified aircraft after the war for maritime patrol, search and rescue and photo-reconnaissance until 1964.<ref name="BAE Systems Avro Lancaster" /> The last flight by the RCAF was by F/L [[Lynn Garrison]] in KB-976, on 4 July 1964 at the [[Calgary]] International Air Show.{{citation needed|date=April 2017}}
:During the Second World War, Canada's [[Victory Aircraft]] (what later became [[Avro Canada]]) was responsible for the development of the Lancastrian, which was duly designated the '''XPP''' for ''Mark 10 Passenger Plane''.<ref name="BAE Systems Avro Lancaster" /> Six were built for [[Trans Canada Airlines]].
:Postwar the RCAF modified the B X (as the Lancaster Mk 10) to fill a variety of roles, with specific designations for each role. These included:
:* '''10AR''': ''Area Reconnaissance'' – three aircraft modified for surveillance operations over the Arctic. Fitted with the lengthened nose ({{convert|40|in|cm}} longer) and carrying cameras and [[ELINT]] equipment. Remained in service until 1964.<ref name="Lyz p25-6">Lyzun ''Air Enthusiast'' March/April 2000, pp. 25–26.</ref>
:* '''10BR''': ''Bomber Reconnaissance''. Minimally modified variant with additional windows for observers in the rear fuselage. 13 converted.<ref name="Lyz p20-1">Lyzun ''Air Enthusiast'' March/April 2000, pp. 20–21.</ref>
:* '''10DC''': ''Drone controller'' with [[Ryan Firebee]] drones – two modified in 1957 and operational until 1961.<ref name="Lyz p25">Lyzun ''Air Enthusiast'' March/April 2000, p. 25.</ref>
:* '''10MR''' (later '''10MP'''): ''Maritime Reconnaissance'' or ''Maritime Patrol'' anti-submarine warfare (ASW) aircraft, based on BR with the mid-upper turret removed. 70–75 converted. In service from 1950 to 1955.<ref name="Lyz p21,4">Lyzun ''Air Enthusiast'' March/April 2000, pp. 21, 24.</ref>
:* '''10N''': ''Navigational trainer''. Five converted.<ref name="Lyz p19-0">Lyzun ''Air Enthusiast'' March/April 2000, pp. 19–20.</ref>
:* '''10O''': ''[[Avro Canada Orenda|Orenda]] jet engine testbed'' for the engine used in the [[Avro CF-100]].<ref name="Lyz p25"/>
:* '''10P''': ''Photo reconnaissance'' mapping duties. 11 converted 1948–1950. Retired 1964.<ref name="Lyz p17-9">Lyzun ''Air Enthusiast'' March/April 2000, pp. 17–19.</ref>
:* '''10S&R''': Interim search-and-rescue aircraft, minimally modified 10S. Replaced by disarmed 10BR and 10MRs.<ref name="Lyz p24-5">Lyzun ''Air Enthusiast'' March/April 2000, pp. 24–25.</ref>
:* '''10S''' : ''Standard'' – designation applied to baseline standard, with Merlin 224 engines, Martin mid-upper turret and H2S radar, for aircraft retained postwar for future use.<ref name="Lyz p16">Lyzun ''Air Enthusiast'' March/April 2000, p. 16.</ref> Sometimes referred to by unofficial designation 10U.<ref name="Lyz p26">Lyzun ''Air Enthusiast'' March/April 2000, p. 26.</ref>
;B.XV
[[File:Avro Lincoln ExCC.jpg|thumb|The sole, Canadian-built, Lancaster B.XV/Lincoln B.XV]]
:As per Lancaster B.IV/Lincoln B.1 but built in Canada and renamed [[Avro Lincoln]] XV. One example was built before the order was cancelled when the war ended.<ref name="BAE Systems Avro Lancaster" />

==Operators==
{{See also|List of Avro Lancaster operators}}
* {{ARG}}
* {{AUS}}
* {{flag|Canada|1921}}
* {{flag|Egypt|1922}}
* {{FRA}}
* {{POL}}
* {{USSR}}
* {{SWE}}
* {{UK}}
* {{NZ}}

==Surviving aircraft==
{{main|List of surviving Avro Lancasters}}
<!--[[File:"City of Lincoln" Lancaster (BBMF).jpg|thumb|[[Battle of Britain Memorial Flight]] painted as "City of Lincoln"]]-->
<!--[[File:Lancaster Mk II NX611 "Just Jane" - geograph.org.uk - 595636.jpg|thumb|Lancaster Mk II NX611 "Just Jane" ]]-->
{{multiple image
 | total_width = 350
 | image1=Avro Lancaster - Shuttleworth Military Pageant 2013 (16379209394).jpg | alt1=British Lancaster PA474
 | image2=Lancaster VR-A.jpg | alt2=Canadian Lancaster FM213
 | footer = The two surviving airworthy Lancasters - PA474 (left) and FM213 (right)
}}
[[File:Airborne Eastbourne International Airshow (14741454419).jpg|thumb|The two surviving airworthy Lancasters during a joint display at the [[Eastbourne Airbourne (air show)|Eastbourne International Airshow]] in 2014]]
Of the 17 surviving and largely intact Lancasters known to exist, two are airworthy: [[Avro Lancaster PA474|PA474]] is a Lancaster B.I operated by the [[Battle of Britain Memorial Flight]], based at [[RAF Coningsby]] in [[Lincolnshire]], UK; [[Avro Lancaster FM213|FM213]], named the "Mynarski Memorial Lancaster" and painted with VR-A (nicknamed VeRA) to honour [[Andrew Mynarski]], is a Lancaster B.X operated by the [[Canadian Warplane Heritage Museum]] in [[Hamilton, Ontario]], Canada.

Two other Lancasters exist with working engines, though not airworthy; like the airworthy pair, these are also found one each in Britain and Canada. The B MkVII ''Just Jane'', NX611, is based in the [[East Kirkby]] [[Lincolnshire Aviation Heritage Centre]], just {{convert|9|miles}} east-northeast of PA474 at RAF Coningsby; it is able to taxi but is not airworthy, though there have been plans to eventually return it to flight. The [[Bomber Command Museum of Canada]], in [[Nanton, Alberta]], is home to FM159, nicknamed Bazalgette, which has been restored from a vandalised state and is able to taxi under its own power.

In 2014, the two airworthy Lancasters (Canadian FM213 and British PA474) toured the UK in a series of joint aerial and ground displays.<ref>[http://www.raf.mod.uk/news/archive/raf-bbmf-to-host-canadian-warplane-heritage-museum-lancaster-during-visit-to-england-24022014 "RAF BBMF to host Canadian Warplane Heritage Museum Lancaster during visit to England."] ''RAF/MoD website News'', 24 February 2014. Retrieved: 14 April 2015.</ref>

In 2017, after more than 50 years on display in [[Edmundston, New Brunswick]], Lancaster KB 882 moved to the [[National Air Force Museum of Canada]] in [[Trenton, Ontario]], where it is to be restored and placed alongside the museum's restored [[RAF]] [[Handley Page Halifax]] [[heavy bomber]], NA 337.<ref>{{cite web|url=http://airforcemuseum.ca/eng/?page_id=767|title=Lancaster KB882 – National Air Force Museum of Canada|date=11 August 2022 }}</ref>

For the 2018 flying season, to commemorate the 75th anniversary of Operation Chastise, the Canadian FM213 Lancaster was painted in the markings used by Guy Gibson's 617 Squadron aircraft (Code AJ-G, ED932) when he commanded the "Dambusters" raids.<ref>{{Cite web |url=https://www.facebook.com/CanadianWarplaneHeritageMuseum/videos/10156123392711280/?t=9 |title=The Lancaster being pushed out of the... – Canadian Warplane Heritage Museum |via=www.facebook.com}}</ref>

==Specifications (Lancaster I)==
[[File:British WW2 bombers comparison.png|thumb|Diagram comparing the Lancaster (blue) with its RAF contemporaries; the [[Short Stirling]] (yellow) and the [[Handley Page Halifax]] (pink).]]
{{Aircraft specs
|ref=''Avro Aircraft since 1908'',<ref name="Jackavro p366">Jackson 1990, p. 366.</ref> ''The Secret Years: Flight Testing at Boscombe Down 1939–1945'',<ref name="Mason, Tim. 1998, p.302"/> ''The Avro Lancaster I: Aircraft in Profile Number 65''<ref name="goul garb 16">Goulding and Garbett 1966, p. 16.</ref>
|prime units?=imp
<!--
        General characteristics
-->
|crew=7: pilot, flight engineer, navigator, bomb aimer/nose gunner, wireless operator, mid-upper and rear gunners
|length ft=69
|length in=4
|length note=
|span ft=102
|span in=0
|span note=
|height ft=20
|height in=6
|height note=
|wing area sqft=1297
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil='''root:''' [[NACA airfoil|NACA 23018]]; '''tip:''' [[NACA airfoil|NACA 23012]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref>
|empty weight lb=36900
|empty weight note=
|gross weight lb=55000
|gross weight note=
|max takeoff weight lb=68000
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=4
|eng1 name=[[Rolls-Royce Merlin XX]]
|eng1 type=V-12 liquid-cooled piston engines
|eng1 hp=1280
|eng1 note=

|prop blade number=3<!-- propeller aircraft -->
|prop name=
|prop dia ft=<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|max speed mph=282
|max speed note= at {{cvt|63000|lb|0}} and {{cvt|13000|ft}} altitude<ref name="Mason, Tim. 1998, p.302"/>
|cruise speed mph=200
|cruise speed note=
|stall speed mph=
|stall speed note=
|never exceed speed mph=
|never exceed speed note=
|minimum control speed mph=
|minimum control speed note=
|range miles=2530
|range note=
|combat range miles=
|combat range note=
|ferry range miles=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling ft=21400
|ceiling note= at {{cvt|63000|lb}}<ref name="Mason, Tim. 1998, p.302"/>
|climb rate ftmin=720
|climb rate note=at {{cvt|63000|lb}} and {{cvt|9200|ft}} altitude<ref name="Mason, Tim. 1998, p.302"/>
|time to altitude=
|wing loading lb/sqft=
|wing loading note=
|fuel consumption lb/mi=
|power/weight=

|more performance=
<!--
        Armament
-->
|guns=Two 0.303-inch (7.7 mm) [[M1919 Browning machine gun#Browning .303 Mark II|Browning Mark II machine gun]]s in nose turret, two 0.303-inch Browning Mark II machine guns in upper turret, and four 0.303-inch Browning Mark II machine guns in the rear turret. (Early aircraft had two Brownings in a ventral turret aimed from within the aircraft via a periscope.)
|bombs=Maximum normal bomb load of {{cvt|14000|lb}} of bombs<ref name="Mason bomber p348">Mason 1994, p. 348.</ref>
|avionics=
* [[H2S (radar)|H2S radar]] in later variants
* T1154 and [[R1155]] radios
* Various other navigational aides and countermeasures
}}

==Notable pilots and crew members==

===Victoria Cross awards===
Many Lancaster crew members were highly decorated for their actions while flying the aircraft. Amongst those who received the [[Victoria Cross]] were:
* [[Squadron Leader]] [[Ian Willoughby Bazalgette]]<ref name="Richards p319">Richards 1995, p. 319.</ref>
* [[Wing commander (rank)|Wing Commander]] [[Guy Gibson]]<ref name="falconer170">Falconer 2003, p. 170.</ref>
* [[Warrant Officer]] [[Norman Cyril Jackson]]<ref name="Richards p303-4">Richards 1995, pp. 304–305.</ref><ref name="goul garb 16"/>
* [[Pilot Officer]] [[Andrew Mynarski]]<ref name="Richards p310">Richards 1995, p. 310.</ref>
* Squadron Leader [[John Dering Nettleton]]<ref name="Richards p157-0">Richards 1995, pp. 157–160.</ref><ref name="goul garb 16"/>
* Squadron Leader [[Robert Anthony Maurice Palmer]]<ref name="Richards p346-7">Richards 1995, pp. 346–347.</ref>
* [[Flight Lieutenant]] [[William Reid (VC)|William Reid]]<ref name="falconer170" />
* [[Flight Sergeant]] [[George Thompson (VC)|George Thompson]]<ref name="falconer170" /><ref name="goul garb 16"/>
* [[Group Captain]] [[Leonard Cheshire]] – for conduct on more than 100 missions in aircraft including the Lancaster, [[de Havilland Mosquito|Mosquito]] and [[North American P-51 Mustang|Mustang]]<ref>{{cite web |title=Cheshire, Geoffrey Leonard |website=tracesofwar.com|url=https://www.tracesofwar.com/persons/30/Cheshire-Geoffrey-Leonard.htm |access-date=15 June 2021}}</ref>
* Captain (acting Major) [[Edwin Swales]]<ref name="falconer170" />

==Notable appearances in media==
[[File:Avro 683 Lancaster B.VII NX671 Baginton 19.06.54.jpg|thumb|When the 1955 film ''[[The Dam Busters (film)|The Dam Busters]]'' was made, the bomb remained classified so the producers created a convincing alternative.]]
{{Main|Aircraft in fiction#Avro Lancaster |l1=Avro Lancaster in fiction}}
<!-- ===============({{NoMoreCruft}})===============-->
<!-- Please READ [[Wikipedia:WikiProject Aircraft/page content#Popular culture]] and [[Wikipedia:WikiProject Military history/Style guide#Popular culture]] before adding any "Popular culture" items.

Please do not add the many minor appearances of the aircraft. This section is only for major cultural appearances where the aircraft plays a MAJOR part in the storyline, or has an "especially notable" role in what is listed. A verifiable source proving the appearance's notability may be required. Random cruft, including ALL Ace Combat, Battlefield, and Metal Gear Solid appearances, and ALL anime/fiction lookalike speculation, WILL BE removed.

If your item has been removed, please discuss it on the talk page FIRST. A verifiable source proving the appearance's notability may be required. If a consensus is reached to include your item, a regular editor of this page will add it back. Thank you for your co-operation.-->

The Avro Lancaster featured prominently in the 1955 film ''[[The Dam Busters (film)|The Dam Busters]]'', and a number of B VII Lancasters in storage were modified to the original configuration of the B.III (Special) for use on screen. Lancasters play a prominent part in ''[[Appointment in London]]'' with Dirk Bogarde.{{citation needed|date=January 2018}}

==See also==
[[File:"Lancaster"_Bombers_are_Smashing_German_Industries_-_DPLA_-_1afce17087d769b0ced5da2c0f20c015.jpg|thumb|Propaganda poster]]
{{Portal|Aviation}}
{{aircontent
|related =
* [[Avro Lancastrian]] (Interim VIP Transport with fairings)
* [[Avro Lincoln]] (originally designated Lancaster Mk.IV, longer wings and fuselage and improved armament)
* [[Avro Lincoln]]ian (Interim VIP transport like Lancastrian but based on Lincoln)
* [[Avro Manchester]] (precursor with unsuccessful Vulture engines)
* [[Avro Shackleton]] (Maritime patrol which used Lincoln wings with new fuselage)
* [[Avro Tudor]] (Airliner with Lincoln Wings and new cigar-shaped fuselage)
* [[Avro York]] (Transport with new fuselage)
|similar aircraft =
* [[Boeing B-17 Flying Fortress]]
* [[Consolidated B-24 Liberator]]
* [[Focke-Wulf Fw 200 Condor]]
* [[Handley Page Halifax]]
* [[Heinkel He 177]]
* [[Messerschmitt Me 264]]
* [[Nakajima G5N]]
* [[Petlyakov Pe-8]]
* [[Piaggio P.108]]
* [[Short Stirling]]
* [[Supermarine B.12/36]]
* [[Vickers Windsor]]
|lists =
* [[List of aircraft of the Royal Air Force]]
* [[List of aircraft of World War II]]
* [[List of bomber aircraft]]
|see also =
}}

==Notes==
{{NoteFoot}}
{{notelist-lr}}

==References==
===Citations===
{{reflist}}

===Sources===
* ''A.P. 22062A-P.N.: Pilot's and Flight Engineer's Notes for Lancaster. Mark I – Four Merlin XX, 22 or 24 Engines. Mark III – Four Merlin 28 or 38 Engines''. London: [[Air Ministry]], May 1944. No ISBN
* {{Citation |last1=Bahnsen|first1=Uwe |first2=Kerstin von |last2=Stürmer |title=Die Stadt, die sterben sollte, Hamburg im Bombenkrieg, Juli 1943 |page=41}}{{full citation needed|date=September 2014}}
* Brickhill, Paul, ''The Dam Busters''. Evans, 1951. 
* Bridgman, Leonard, ''Jane's Fighting Aircraft of World War II''. New York: Crescent Books, 1988. {{ISBN|0-517-67964-7}}.
* Brown, Eric, ''Wings on my Sleeve''. London: [[Weidenfeld & Nicolson]], 2016. {{ISBN|978-0-7538-2209-8}}.
* Buttler, Tony, ''British Secret Projects: Fighters & Bombers 1935–1950''. Hinckley: Midland Publishing, 2004. {{ISBN|1-85780-179-2}}.
* Chant, Christopher, ''Lancaster: The History of Britain's Most Famous World War II Bomber''. Bath, UK: Parragon, 2003. {{ISBN|0-7525-8769-2}}.
* Chorlton, Martyn, ''Avro Lancaster Mk I and Mk III: Database''. Cudham, Kent, UK: Kelsey Publishing, 2011.
* {{Citation |last=Collier |first=Basil |year=1976 |orig-year=1964 |title=The Battle of the V-Weapons, 1944–1945 |publisher=The Emfield Press |location=Yorkshire |isbn=0-7057-0070-4 |pages=68, 84}}
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* {{cite book |last=Flower |first=Stephen |title=The Dambusters: An Operational History of Barnes Wallis' Bombs |year=2013 |orig-year=2009 |publisher=Amberley Books |location=Stroud |edition=e-book |isbn=978-1-4456-1828-9}}
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*{{cite magazine |last=Gardner |first=Brian |title=Flight Refuelling... The Wartime Story |magazine=[[Air Enthusiast]] |issue=25 |pages=34–43, 80 |date=1984 |issn=0143-5450}} 
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* Holmes, Harry, ''Avro Lancaster. The Definitive Record 2nd Edition.'' Shrewsbury, UK: Airlife Publishing Ltd, 2001. {{ISBN|1-84037-288-5}}.
* "The Immortal Lanc". ''Wings'' Volume 1, Part 8, 1977. London: Orbis Publishing Ltd.
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==Further reading==
* {{cite book |editor-first=Jorge Felix |editor-last=Núñez Padin |last=Benedetto |first=Fernando |title=Avro Lancaster, Lancastrian & Lincoln |url=http://www.fuerzasaeronavales.com/?p=1018 |url-status=dead |series=Serie Fuerza Aérea |publisher=Fuerzas Aeronavales |location=Bahía Blanca, Argentina |volume=17 |year=2009 |archive-url=https://web.archive.org/web/20110922193646/http://www.fuerzasaeronavales.com/?p=1018 |archive-date=22 September 2011 |isbn=978-987-1682-00-3 |language=es}}
* {{cite book |last=White |first=Glenn |title=Avro Lancaster: The Survivors |publisher=Mushroom Model Publications |year=2010 |isbn=978-8389450470}}

==External links==
{{Commons category|Avro Lancaster}}
* [http://www.lancaster-archive.com The Lancaster Archive]
* [http://www.flightglobal.com/pdfarchive/view/1942/1942%20-%201692.html "The Avro Lancaster"] a 1942 ''Flight'' article
* [https://ibccdigitalarchive.lincoln.ac.uk/omeka/items/browse?tags=Lancaster Lancaster at the International Bomber Command Centre Digital Archive]

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