Editing Avro Lancaster (section)

===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"/>