The Lancaster flew for the first time on January 9, 1941 as a four-engine development of the Avro Manchester. The RAF began to equip with Mk Is in early 1942, and used them first on March 10th against targets in Essen. Altogether, more than 7,300 Lancasters were produced in Britain as Mks I to VII and in Canada as Mk Xs, and they dropped more than 608,000 tons of bombs on 156,000 wartime missions. Some Lancasters were still flying with the RAF in the early 1950s as maritime-reconnaissance, photo-reconnaissance and rescue aircraft.

    Like all successful aircraft, the Lancaster not only looked good but its flying characteristics matched its appearance. It is all the more ironic therefore that the birth of Avro's mighty machine owed so much to failure, the failure of its immediate predecessor, the twin engine Avro Manchester. The Avro 683 evolved almost accidentally as a result of recurrent failure of the insufficiently developed Rolls Royce Vulture engines installed on the Manchester.

    Large when compared with other twin engine aircraft the P.131/36 was actually powered by four Rolls-Royce engines. Under the designation Vulture, Rolls-Royce had mated a pair of V12 cylinder Kestrel engines with a common crankcase creating a 24 cylinder "X" engine and a lot of trouble. On July 25, 1939, the prototype, L7246 was flown for the first time with Group Captain H.A. Brown at the controls. While airborne for only 17 minutes, it was long enough to realize that the Vulture engines were turning out much less power than anticipated and wing loading made the aircraft extremely difficult to fly.

    To correct lateral instability a central fin was added to the second prototype, L7247, which flew for the first time on May 26,1940. The second machine was armed with six .303 Browning machine guns, two in the nose, ventral and tail turrets. Production quickly followed with the first production machine, L7276, rolling out on August 5, 1940 during the height of the Battle of Britain. Production machines had a wing span increase and the ventral turret was removed to the dorsal position. The need for additional modifications and the urgency of manufacturing fighters slowed down production of the P.13136, which was now known as the Manchester. L7277. The second production machine, was not delivered until October 25, 1940.

    Problems with the Vulture power plants were not so easily solved however, and No. 207 Squadron seldom had more than five machines serviceable at one time. On the night of March 13, 1941, the first Manchester was lost to enemy action when L7319 was shot down shortly after takeoff from Waddington by Feld W. Hans Hahn of I/NJG 2. Most of the Manchester's mechanical problems by now had been solved and a second assembly line, at Metropolitan Vickers, which began turning out machines for the new Squadrons being formed. The basic problem with the Manchester, that of being underpowered, was still to be addressed. With a service ceiling of only 10,000 feet, the loss of one engine resulted in an almost immediate loss of height. The poor performance of the Manchester caused one squadron to (only half-jokingly) plan their squadron reunion in POW camp.

    In April, all Manchesters were grounded when faults were found in the Vulture engine bearings. On June 16, the Manchesters were again grounded to modify the cooling system, and again on June 30 for complete engine overhauls and testing, the results of which were a further series of modifications.

    On August 7, operations were resumed at which time two further faults showed up. The tail flutter, which was eventually corrected by redesigning the tail to an enlarged twin fin configuration under the designation Manchester IA, and the propeller feathering problem which was not so easily traced. Engine problems seemed to increase rather than abate and casualties grew.

    During initial trials of the Manchester prototype, it had been quickly realized that the 24 cylinder Vultures were not turning out the anticipated power. Two projects were initiated to correct the situation, replacement of the Vultures with a pair of Napier Sabre or Bristol Centaurus engines, keeping the twin engine configuration under the designation Manchester Mk II, or by reconfiguring the aircraft to a four engine machine under the designation Manchester Mk III. The four engine solution was completed first, and so successfully that the twin engine projects were dropped out of hand.

    BT308, a standard Manchester airframe, was fitted with a new wing center section into which were installed four of the very reliable Rolls-Royce Merlin X engines. Flying for the first time on January 9, 1941, that flight was enough to convince Roy Dobson and his designers that true success had been achieved.

    The doubling from two to four motors meant an increase in the Manchester's maximum bomb load, from 10,350 lbs to an operational average of 12,000/14,000 lbs. Fuel capacity was increased from 1,700 to 2,154 gallons and range increased from 1,200 miles to 2,350 miles. Bomber Command now had a bomber that could penetrate deep into Nazi occupied Europe with a much larger bomb load and could reasonably expect to evade or fight off all that the enemy could provide in defensive measures—and at an altitude more than double the Manchester's meager 10,000 foot ceiling. Of even more importance to the crews flying the bomber into enemy air space was the security afforded them by the reliability of the newly installed Merlin power plants.

    Official testing at Boscombe Down during March found that the elevators and ailerons responded well at either end of an I.A.S. range of 100 to 290 mph, but rudder pressure did increase with speed. The strong tendency to swing to port during takeoff was solved by advancing the port-outer throttle and raising the tail quickly, to allow the pilot to bring the rudders into play.

    In May the second prototype, DG595, took to the air. In contrast to BT308, she carried both mid-upper and ventral turrets and a newly designed and enlarged twin tail configuration which discarded the center fin. New 1,280 HP Merlin XX engines had been installed in place of the earlier Merlin Xs. The RAF now had a bomber with which it could wage war in Germany. There would be no more talk around the squadrons about reunions in POW camp!