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The Avro 679 Manchester was a British twin-engine heavy bomber developed and manufactured by the Avro aircraft company in the United Kingdom. While not being built in great numbers, it was the forerunner of the more famed and more successful four-engined Avro Lancaster, which was one of the most capable of the Second World War.
Avro designed the Manchester in conformance with the requirements laid out by the British Air Ministry Specification P.13/36, which sought a capable medium bomber with which to equip the Royal Air Force (RAF) and to replace its twin-engine bombers, such as the Armstrong Whitworth Whitley, Handley Page Hampden and Vickers Wellington. Performing its maiden flight on 25 July 1939, the Manchester entered squadron service in November 1940, just over twelve months after the outbreak of the war.
Operated by the RAF and the Royal Canadian Air Force (RCAF), the Manchester came to be regarded as a failure, primarily as a result of its Rolls-Royce Vulture engines, which were underdeveloped and hence underpowered and unreliable, and production was terminated in 1941. The Manchester was redesigned as a four-engined heavy bomber, powered by the Rolls-Royce Merlin engine instead, which became known as the Lancaster.
Avro had already started work on a corresponding design prior to having received a formal invitation to tender. The company was in competition with Boulton Paul, Bristol, Fairey, Handley Page and Short Brothers. Vickers also had its Warwick, which had Napier Sabre engines but eventually chose against tendering it. In early 1937, the Avro design and the rival Handley Page HP.56 were accepted and prototypes of both ordered but in mid-1937, the Air Ministry exercised their right to order the types "off the drawing board". This skipping of the usual process was necessary due to the initiation of a wider expansion of the RAF in expectation of another great European war. From 1939, it was expected that the P.13/36 would begin replacing the RAF's medium bombers, such as the Armstrong Whitworth Whitley, Handley Page Hampden and Vickers Wellington.
The Avro design used the Rolls-Royce Vulture 24-cylinder X engine, which was two Rolls-Royce Peregrine V engine mounted one on top of the other, the bottom one inverted to give the "X" shape.Bowyer 1974, p. 26. When developed in 1935, the Vulture engine had promise — it was rated at but it proved woefully unreliable and had to be derated to . Avro's prototype Manchester L7246, was assembled by their experimental department at Manchester's Ringway Airport and first flew on 25 July 1939, with the second aircraft following on 26 May 1940.Bowyer 1974, pp. 28–29. The Vulture engine was chosen by Avro and not stipulated by the Air Ministry as is sometimes claimed; other engine layouts considered were the use of two Bristol Hercules or Bristol Centaurus . The Handley Page HP.56, always intended as the back-up to the Avro, was redesigned to take four engines on the orders of the Air Ministry in 1937, when the Vulture was already showing problems.Lake 2002, p. 90.
While the Manchester was designed with a twin tail, the first production aircraft, the Mk I, had a central fin added and twenty aircraft like this were built. They were succeeded by the Mk IA which reverted to the twin-fin system with enlarged and taller fins and mounted on a new tailplane, with span increased from to . This configuration was carried over to the Lancaster, except for the first prototype, which also used a central fin and was a converted, unfinished Manchester.Lake 2002, p. 89. Avro constructed 177 Manchesters while Metropolitan-Vickers completed 32 aircraft. Plans for Armstrong Whitworth and Fairey Aviation at Ringway (now Manchester Airport) to build the Manchester were abandoned. Fairey's order for 150 Manchesters was replaced by orders for the Halifax.
The cockpit housed the pilot and fighting controller's position underneath the canopy, and these two crew members were provided with all-round vision. The navigator was seated aft of the fighting controller and the position included an astrodome for use of a sextant. The bomb aimer's station was housed inside the aircraft's nose, beneath the forward turret and bomb aiming was conducted using optical sights housed in this compartment.Flight 1942, p. 557. For crew comfort on lengthy missions, a rest area was situated just to the rear of the main cabin.Bowyer 1974, p. 28.
The aircraft's undercarriage was entirely retractable via hydraulic systems, or in an emergency, a backup air system. The doors to the bomb bay were also operated by these systems, an additional safety measure was installed to ensure that the bombs could not be dropped if the doors were shut. The bombs were housed on bomb racks inside the internal bomb bay, and other armaments such as torpedoes could also be fitted. All fuel tankage was located in the wings in order to keep the fuselage free to accommodate more armaments in the bomb bay which covered nearly two-thirds of the underside of the fuselage.
Vulnerable parts of the aircraft were armoured; the pilot had additional armour and bulletproof glass and an armoured bulkhead was to the rear of the navigator's position. The Manchester featured three hydraulically-operated turrets, located in the nose, rear and mid-upper fuselage; the addition of a ventral turret directly behind the bomb bay had been considered and tested on the second prototype, but did not feature on production aircraft. Access to all crew stations was provided by a walkway and crew positions had nearby escape hatches. Flight 1942, pp. 556–557.
The Manchester was powered by a pair of Vulture engines; in service these proved to be extremely unreliable. Aviation author Jon Lake stated of the Vulture: "The engine made the Manchester mainly notable for its unreliability, poor performance, and general inadequacy to the task at hand" and attributed the aircraft's poor service record to the engine troubles.
I was one of the six original pilots to have flown with the first Manchester squadron. That was a disaster. The aircraft itself, the airframe, had many shortcomings in equipment in the beginning, but as we found out Avro were excellent in doing modifications and re-equipping the aeroplane. The engines never were and never did become reliable. They did not give enough power for the aeroplane, so we ended up with two extremely unreliable 1,750 hp engines having to haul a 50,000-pound aircraft. We should really have had 2,500 hp engines. You felt that if you'd lost one, that was it, you weren't coming home. It didn't matter if you feathered the propeller or not. There was only one way you went and that was down. I have seen an aircraft doing a run up on the ground and have two pistons come right out through the side of the engine. The original bearings were made without any silver as an economy measure, so they weren't hard enough. The bearings would collapse the connecting rod and the piston would fling out through the side of the engine and bang! Your engine just destroyed itself. "Before the Lancs", Early Days, Personal Stories, The Bomber Command Association
On 13 April 1941, all Manchesters were temporarily grounded due to a higher than expected number of engine bearing failures; on 16 June 1941, a second grounding of the type was ordered due to more engine troubles.Bowyer 1974, p. 32. The unserviceability of the Vulture engine forced squadrons to make use of obsolete bombers such as the Hampden in its place. Upon the restart of operations in August 1941, additional failings were encountered; excessive tail flutter, hydraulic failures and faulty propeller feathering controls.Bowyer 1974, p. 33. Production of the Manchester was halted in November 1941, by which point a total of 202 aircraft had been constructed. A total of eight bomber squadrons were equipped with the type, it also served in two further squadrons and also saw use by RAF Coastal Command.
While modifications were made by Avro to address some of the technical issues experienced, unit strength suffered and Bomber Command was frequently unable to raise significant numbers of aircraft to participate in large bombing missions; on 7 November 1941, all of the RAFs serviceable bombers had been dispatched to bomb Berlin, out of a force of over 400 bombers, only 15 were Manchesters.Bowyer 1974, p. 34. On 3 March 1942, out of a force of nearly 200 bombers sent against a Renault factory near Paris, 25 were Manchesters;Bowyer 1974, p. 35. while during the first 1,000 bomber raid on Cologne on 30 May 1942, 35 Manchesters were amongst the 1,047 bombers sent to attack the city.Bowyer 1974, p. 38. Flying Officer Leslie Manser was posthumously awarded the Victoria Cross for his actions while piloting Manchester L7301 of 50 Squadron during the Cologne bombing mission.Bowyer 1974, pp. 38, 41.
The Mk III Manchester (serial number BT308) which first flew on 9 January 1941, was essentially the first Lancaster, featuring a longer wing fitted with four Rolls-Royce Merlins in new unitized, power-egg nacelles – originally developed by Rolls-Royce for the Merlin-powered Beaufighter II – although initially retaining the three fins and twin outboard rudders (the central fin had no movable control surface) of the Manchester I. BT308 received the "Lancaster" name immediately after its first flight. The second prototype Lancaster DG595 featured the twin, enlarged fins and rudders of the Manchester IA. Manchester production continued until November of that year but some aircraft that were still in production were instead completed as Lancasters.
The 193 operational Manchesters flew 1,269 sorties with Bomber Command, dropping 1,826 tons (1,657 tonnes) of bombs and lost 78 aircraft in action, flying its last operation against Bremen on 25 June 1942.Jackson 1990, p. 356.Bowyer 1974, p. 43. A further 45 were non-operational losses of which 30 involved engine failure. The Manchester was withdrawn from operations in mid-1942 in favour of more capable aircraft. Its final role in RAF service was as instructional trainers for converting crews to the RAF's new Lancaster bombers; the Manchester and Lancaster shared nearly identical crew positions and fuselages. The type persisted in use for training purposes into 1943 before being completely retired.
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