The four-engined Avro Lancaster heavy bomber was designed and built by A V Roe & Company for the RAF during the Second World War. Entering service with Bomber Command in 1942, it soon became their main heavy bomber.
Its origins are with a twin-engined bomber design submitted to meet Air Ministry Specification P13/36, which resulted in the Avro Manchester. Although a capable aircraft, the Manchester proved underpowered with its Rolls-Royce Vulture engines and was withdrawn from service in 1942. Avro Chief Designer Roy Chadwick had been already working on an improved Manchester design, using four of the more reliable but less powerful Rolls-Royce Merlin engines, fixed on larger wings. The aircraft, initially designated Avro Type 683 Manchester III, was later renamed the Avro 683 Lancaster.
The prototype aircraft (BT308) was assembled by Avro's Experimental Flight Department at Manchester's Ringway Airport and made its first flight on 9th January 1941. It proved to be a great improvement on its predecessor. Its initial three-finned tail layout was quickly changed on the second prototype (DG595) and on subsequent production aircraft to the familiar twin-finned specification.
The Avro Lancaster is officially described as a mid-wing, cantilever monoplane with an all-metal fuselage. The wings were constructed in five main sections, as was the fuselage. All the main sections were built separately, often at different locations. All required equipment was fitted before transport to various sites for final assembly. Initially, the Lancaster was powered by four Rolls-Royce Merlin water-cooled piston engines driving de Havilland Hydromatic three-bladed airscrews, with a retractable main landing gear and fixed tail-wheel.
The majority of the aircraft built during the war years were manufactured by Avro at the factory at Chadderton near Oldham, Lancashire. They were then assembled and test flown from Woodford Aerodrome in Cheshire. Others were built by Armstrong-Whitworth, Metropolitan-Vickers, Vickers-Armstrongs, and Victory Aircraft in Canada, while still more were produced by the Austin Motor Company in Longbridge, Birmingham and at Chester and Castle Bromwich (both Vickers-Armstrong's factories).
A long, unobstructed bomb bay enabled the Lancaster to carry the largest bombs used by the RAF, including the 4,000, 8,000, or 12,000 lb Blockbusters. The types' versatility was such that it was chosen to equip 617 Squadron, modified to carry the Barnes Wallis designed 'Bouncing bomb' used on Operation Chastise, the attack on dams in Germany's Ruhr Valley.
Although the Lancaster was primarily a night bomber, it excelled in many other roles including daylight and precision bombing raids. In the latter role, some were adapted to carry the 12,000 lb Tallboy and ultimately, the 22,000 lb Grand Slam 'earthquake' bombs (also designed by Barnes Wallis).
Postwar, the Lancaster was replaced as the RAF's main strategic bomber by the Avro Lincoln, a larger development of the Lancaster. The Lancaster also took on the role of long range anti-submarine patrol aircraft although it was later superceded by the Avro Shackleton, especially in air-sea rescue operations. It also performed roles as diverse as photo-reconnaissance and aerial mapping. It served as a flying tanker for aerial refuelling whilst in its later jet-powered Avro Lancastrian configuration, it was operated by companies such as the British Overseas Airways Corporation (BOAC) as a long-range, high-speed transatlantic VIP passenger and postal delivery airliner. In 1946, a Lancastrian of British South African Airways (BSAA) flew the first scheduled flight from the then new London Heathrow Airport to Buenos Aires, Argentina, with other routes stretching as far as Australia.