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Bomber Comparisons 1941

Discussion in 'Allied Bomber Planes' started by Jim, Aug 19, 2007.

  1. Jim

    Jim New Member

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    It has often been said that the Lancaster arose from the failure of the Manchester. This is not entirely true; as early as the autumn of 1938, long before the first flight of the Manchester prototype, A. V. Roe's design office considered the possibility of a four-engined variant of the Type 679. But with other priorities in the design offices, only the most basic work was done at this stage on what was to become the Avro Type 683.

    As a safeguard against a shortage of Merlins, the Mk 11 Lancaster was powered by Bristol Hercules radial engines. Only 300 were built.

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    The first four-engined bomber to enter service with Bomber Command was the Short Stirling. It was inferior to the Lancaster in both performance and load-carrying.

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  2. Jim

    Jim New Member

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    Type 683, known in the design office as the Lancaster from a very early stage, was developed around the Manchester fuselage and wing centre section. The crew cabin had been highly praised, while the cavernous bomb bay met all current and not a few future requirements. The overall wingspan was substantially increased to accommodate the outboard engines, which also had the effect of improving take-off performance, while various other detail modifications were made.

    A turning point came at the end of August 1940, when the decision was taken that Bomber Command's strategic force would be entirely equipped as soon as possible with four-engined bombers. In retrospect this decision seemed extraordinary, if only because the Stirling had barely started reaching its first squadron, while the service entry of the Halifax was still three months in the future, as was that of the Manchester. The four-engined heavy bomber had yet to prove itself, but there remained one sound operational reason for the decision. Even reliable engines failed occasionally, and all were vulnerable to flak and fighters. The failure of one engine in a four-engined type was much less serious than the same case in a twin, in which a full 50 per cent of the available power was lost, and asymmetric handling problems, with all the remaining power on one side, were far more extreme.

    The Avro Type 683 prototype was initially known as the Manchester III, and only later renamed the Lancaster I.

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    The decision to proceed with the four-engined Avro bomber was taken, although as a security measure the name Lancaster was dropped and the Type 683 became known as the Manchester Mark III, the Mark II designation having been reserved for the Napier Sabre-powered aircraft, which in fact was never built. The prototype used a Manchester I airframe powered by Merlin Xs, and retained the short-span tailplane and triple fin layout of that aircraft. The first flight took place on 9 January 1941.
    Trials at Boscombe Down showed good handling qualities although, as was only to be expected, directional stability was lacking. This was cured by a new tailplane of almost double the span of the original and very much larger twin fins and rudders, with the central fin removed. With the new Merlin XXs fitted, the prototype reached a maximum speed of 310mph (500km/hr) at 21,000ft (6,400m) - an outstanding performance for a heavy bomber of that era. A new production contract was issued; limiting the output of Manchester’s to 200 before switching to the Lancaster, as it had inevitably become known. The use of Manchester sub-assemblies speeded up this process.
     
  3. Jim

    Jim New Member

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    Second Prototype

    The second Lancaster prototype, which made its maiden flight on 13 May 1941, was rather nearer to the production machine standard, stressed for an all-up weight of 60,0001b (27.22 tonnes), and with a dorsal gun turret fitted. It retained the ventral turret for the time being. This was followed into the air by the third prototype on 26 November of that year, which was powered by Hercules VI radials, and as such became the prototype Lancaster Mark H. But long before the radial-engined machine took to the air, production Mark Is were rolling off the lines. The production aircraft still showed their Manchester origins, but had been refined in many ways. All-up weight had been increased to 65,000lb (29.48 tonnes) maximum, although this could be exceeded in an emergency; maximum bomb load had been increased to 14,OOOlb (6.35 tonnes); two extra fuel tanks had been fitted in the wings, and the ventral turret had been deleted as being of no earthly use at night. A collar fairing had been added around the mid-upper turret to prevent the guns being depressed enough to damage the aircraft, and a four-gun turret was standard in the tail position. The crew consisted of seven men; the pilot, who was also the aircraft captain, regardless of rank; a second pilot, who was quickly replaced by the new category of flight engineer; a bomb aimer, who also manned the front turret; a navigator, a wireless operator, and mid-upper and tail gunners.


    The second Lancaster prototype introduced a ventral turret that was fitted to early production aircraft.

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  4. Jim

    Jim New Member

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    The Avro's attire is sombre, a staid dull black on undersides of wings and tail and fuselage sides complemented by a tasteful camouflage scheme on top. Guns protrude from turrets in her nose and tail and mid-way down her upper fuselage.

    The standard camouflage scheme was dark green and dark earth disruptive pattern above and matt black below.

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    Right in the front of her nose is a hemispherical transparent dome, with a round optically flat panel looking downwards. This is where the real business is done; through this the bombs are aimed. Right in front of her nose is a hemispherical transparent dome, with a round optically flat panel looking downwards. This was where the real business was done; through this the bombs were aimed. Above is a turret from which project the muzzles of two .303 Browning machine guns. Immediately behind the turret is a glazed cabin for the pilot and his flight engineer.
    It has a huge bomb bay, which starts almost immediately beneath the front of the cabin and reaches back beyond the wing trailing edge to a point almost level with the dorsal turret.

    The open doors give some idea of the vast size of the bomb bay. The bombs were released in a preset sequence.

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    It was the norm before engine start-up, that the bomb bay doors were opened, revealing the sinister outlines of the contents. In the centre was a large, dark green cylinder, a 4,0001b (1,800kg) high explosive 'cookie'. It was surrounded by twelve SBCs (Small Bomb Containers) filled with incendiaries. This was the most usual Lancaster bomb load.
     

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