Editing Avro Lancaster (section)

==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>