All together, there were some 7 different four engined heavy strategic bombers from a number of manufacturers in wartime service with the RAF: 1. The Short Stirling, introduced in 1939 The Stirling was a huge aircraft but it suffered from some deficiencies which were never really overcome, even in the later variants, one of the two major problems was found in the tail-wheel assembly which caused problems in all versions, despite many modification attempts, the other major problem was an initial design flaw; the wing span was too short for the size of the aircraft. This meant that the Stirling was unable to reach its design operational ceiling and when it was deployed with other types resulted in it either being within the range of flak or the risk of being bombed from above. The Stirling survived war service and was later redeployed to RAF Transport Command. 2. The Consolidated B-24 Liberator (1939) Known to its American users as the B-24, the Liberator was used in limited numbers by the RAF in the bomber, transport and maritime roles. It was found to be less than effective as a bomber in the European Theatre and almost all were transferred to Coastal Command where due to their extended operating range and armed with depth charges instead of bombs they became an effective counter to the U-boat packs in the “Black Gap” between Iceland and the Western Approaches. The USAAF did employ relatively large numbers of the B-24 in its bombing role over Europe. Prime Minister Winston Churchill used a Liberator as his personal transport aircraft during his visits to the Western Desert and also to Russia to meet with Stalin. In the transport role Liberators were widely deployed in both the bomber and transport roles in the Far East and were sometimes used for “Flying the Hump”; the dangerous route over the mountains to supply Chiang Kai-shek’s Chinese Nationalist forces after the Japanese had cut the “Burma Road”. 3. The Handley-Page Halifax (1939) Developed from a twin engine design, the Halifax was never as successful as the Lancaster, although it more than adequately accomplished the tasks assigned to it. The Halifax was widely used on minelaying operations, dropping maritime mines into German shipping lanes from low level. Modified Halifaxes were used by SOE for supply drops to the resistance and inserting agents by parachute. At the end of the war many Halifaxes were modified and transferred to the transport role. 4. The Avro Lancaster (1941) Originally developed from the less than successful twin engined Avro Manchester, the Lancaster went on to achieve legendary status. The highly versatile Lancaster was the main aircraft used RAF Bomber Command from late 1942 until the end of the war, meeting all the challenges thrown its way. The Lancaster carried the “upkeep” mine on the famous Dambusters raid and was also able to carry the 5 ton “Tallboy” used against the German battleship “Tirpitz” and the huge 10 ton “Grand Slam” bomb used against bridges and viaducts. 5. Boeing B-17 Fortress (1942) The mainstay of the USAAF (The Mighty Eighth) bombing effort in the European Theatre. The B-17 was deployed mainly in highly dangerous American campaign of daylight bombing operations from high altitude. The RAF did equip a small number of squadrons with the B-17 and was known as the Fortress; sometimes as the “Flying Fortress”. The RAF deployed the “Fortress” mainly for electronic counter measures (ECM), in those days, limited to jamming radio communications signals and some radar tracking systems, ECM was in its infancy during the war, although the main anti-radar technique was “window”; bundles of small aluminium foil strips dropped from aircraft to make large false and misleading echoes on enemy radar screens. 6. Boeing B-29 Washington (1944) Although considered for other theatres, and briefly evaluated in England, the B-29 was exclusively used in World War II in the Pacific Theatre. The use of YB-29-BW 41-36393, the so-named Hobo Queen, one of the service test aircraft flown around several British airfields in early 1944, was thought to be as a “disinformation” program intended to deceive the Germans into believing that the B-29 would be deployed to Europe. Postwar, several RAF Bomber Command squadrons were equipped with B-29s loaned from USAF stocks. The aircraft were known as the Washington B.1 in RAF service, and remained in service from March 1950 until the last bombers were returned in early 1954, having been replaced by deliveries of the English Electric Canberra bombers. 7. Avro Lincoln (1944) The Lincoln was a “redesign” of the Lancaster, and although it’s listed as entering service in 1944; it first flew three days after D-Day, on the 9th June and became operational in August 1945. The Lincoln didn’t see active service in the war but it was deployed on active service in Kenya during the Mau-Mau uprising and also during the Malayan Emergency in the early 1950s. It was the mainstay of the RAF bomber force until the introduction of jet powered aircraft such as the Canberra.