The Avro 683 Lancaster Bomber was a four-engine heavy bomber flown by the Royal Air Force and allies during the Second World War (1939-45). Lancasters were particularly used in nighttime bombing raids and could carry the heaviest bombs ever dropped in WWII. Lancasters dropped the 'bouncing bombs' on several Ruhr dams in Operation Chastise, the 'Dam Buster' raid of May 1943. Design Origins...