The original design was for a twin-engined heavy bomber to be powered by the Rolls-Royce Vulture engines. The resultant aircraft was the Avro Manchester, a disappointing aircraft that was doubly hampered by the unreliable engines, it was withdrawn from service in 1942 with only 200 aircraft built.
When the Vulture proved unreliable, A. V. Roe's chief designer Roy Chadwick switched to a design using four more reliable Rolls-Royce Merlin engines instead. The result was the aircraft was initially called the Type 683. Renamed the Lancaster it made its first test flight on January 9, 1941.
The majority of Lancasters were manufactured by Metropolitan-Vickers, Armstrong Whitworth and A.V. Roe. Only 300 of the Mk. II with Bristol Hercules engines were made. The Mk. III had newer Merlin engines but was otherwise identical to earlier versions; 3030 Mk. IIIs were built, almost all at A.V. Roe's Newton Heath factory. Of later versions only the Canadian-built Mk. X was produced in any numbers, built by Victory Aircraft in Malton, Ontario. 430 of this type were built. They differed little from earlier versions, except for using Packard built Merlin engines and having a differently configured mid-upper turret. 7,377 Lancasters of all marks were built over the war; a 1943 Lancaster cost £4545-50,000.
The Lancasters flew 156,000 operations and dropped 608,612 tons of bombs. 3,249 Lancasters were lost in action. Only 35 Lancasters completed more than 100 successful operations. The greatest survivor completed 139 operations and survived the war to be scrapped in 1947.
An important feature of the Lancaster was its extensive bomb bay, at 33 feet (10.05 metres) long. Initially the aircraft carried 4,000 lb (1,818 kg) bombs or for special targets the 21 feet (6.4 metres) long 12,000 lb (5,455 kg) 'Tall Boy'. Towards the end of the war, attacking hardened targets, the 'Special B' Lancasters could carry a single 25.5 feet (7.77 metres) long 22,000 lb (10,000 kg) 'Grand Slam' or 'Earthquake' bomb. The Lancaster was primarily a night-time bomber.
The Lancaster had a very advanced communications system for its time; the famous 1155 receiver and 1154 transmitter. These provided radio direction-finding, as well as voice and morse capabilities. Later Lancasters carried primitive radar installations.
The most famous use of the Lancaster was probably the 1943 mission, codenamed Operation Downwood, to destroy the dams of the Ruhr Valley using special drum shaped "bouncing bombs" carried by modified Mk. IIIs. The story of the mission was later made into a film, The Dam Busters.
There was a civilian airliner based on the Lancaster, known as the Lancastrian. It was a Lancastrian that was involved in the famous stendec incident.
Two Avro Lancasters remain in air-worthy condition, although few flying hours remain on their airframes and actual flying is carefully rationed. One is PA474 of the Battle of Britain Memorial Flight and the other is FM 213 of the Canadian Warplane Heritage Museum.
Avro Lancaster Mark I