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Thread: B17's in RAF markings ...

  1. #16
    Member Son of Damian's Avatar
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    There was a great article in the online aviation journal Chandelle about this subject back in 2005. I don't have a digital copy of the article, but I did save these profiles.



    From what I remember of the article, RAF Bomber command used the B-17 C model for high altitude precision bombing in 1941-42 when the US thought the norden bombsight could do magical things for bombing accuracy. The raids were generally unsuccessful thanks to weather, mechanical problems, and really poor bombing accuracy. One unfortunate bomber and crew became one of the few victims of the Bf-109 T, the extended wing aircraft carrier version of the 109E, being intercepted around 30K ft over southern Norway.

  2. #17
    Bush Lawyer, that's me! TheKiwi's Avatar
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    My recollection was that the RAF versions didn't get the Norden bombsight.

  3. #18
    Senior Member Warden's Avatar
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    Quote Originally Posted by TheKiwi View Post
    My recollection was that the RAF versions didn't get the Norden bombsight.
    We didn't.

    British interest, Tizard mission

    By mid-1938 information about the Norden had worked its way up the Royal Air Force chain of command and was well known within that organization. The British were in the midst of developing their own Stabilized Automatic Bomb Sight (SABS), but it would not be available until 1940 at the earliest, and likely later. Even then, it did not feature the autopilot linkage of the Norden, and would thus find it difficult to match the Norden's performance in anything but smooth air. Acquiring the Norden became a major goal.[17]
    Their first attempt, in the spring of 1938, was rebuffed by the Navy. Sir Edgar Ludlow-Hewitt, Chief Marshal of Bomber Command, demanded Air Ministry action, and they wrote to George Pirie, the British air attaché in Washington, suggesting he approach the Army with an offer of an information exchange with their own SABS. Pirie replied that he had already looked into this, and was told that the Army had no licensing rights to the device. The matter was not helped by a minor diplomatic issue that flared up in July when a French air observer was found to be onboard a crashed Douglas Aircraft Company bomber, forcing President Roosevelt to promise no information exchanges with foreign powers.[18] Six months later, after a change of leadership within the Navy's Bureau of Aeronautics, on 8 March 1939 Pirie was once again instructed to ask the Navy about the Norden, this time sweetening the deal with offers of British power-operated turrets.[18] However, Pirie expressed concern as he noted the Norden had become as much political as technical, and its relative merits were being publicly debated in Congress weekly while the Navy continued to say the Norden was "the United States' most closely guarded secret".[19]
    The RAF's desires were only further goaded on 13 April 1939, when Pirie was invited to watch an air demonstration at Fort Benning where the painted outline of a battleship was the target. "At 1:27 while everyone was still searching [the sky for the B-17s] six 300-pound bombs suddenly burst at split second intervals on the deck of the battleship, and it was at least 30 seconds later before someone spotted the B-17 at 12,000 feet."[20] The three following B-17s also hit the target, and then a flight of a dozen Douglas B-18 Bolos placed most of their bombs in a separate 600 by 600 yard square outlined on the ground.
    A change of management within the Bureau of Aeronautics had the effect of making the Navy more friendly to British overtures, but no one was willing to fight the political battle needed to release the design. The Navy brass was concerned that giving the Norden to the RAF would increase its chances of falling into German hands, which could put the US's own fleet at risk.[21] The Air Ministry continued increasing pressure on Pirie, who eventually stated there was simply no way for him to succeed, and suggested the only way forward would be through the highest diplomatic channels in the Foreign Office. Initial probes in this direction were also rebuffed.[21] When a report stated that the Norden's results were three to four times as good as their own bombsights, the Air Ministry decided to sweeten the pot again, and suggested they offer information on radar in exchange. This too was rebuffed.
    The matter eventually worked its way to Prime Minister Neville Chamberlain, who wrote personally to President Roosevelt asking for the Norden, but even this was rejected.[21] The reason for these rejections more political than technical, but the Navy's demands for secrecy were certainly important. They repeated that the design would be released only if the British could demonstrate the basic concept was common knowledge, and therefore not a concern if it fell into German hands. The British failed to convince them, even after offering to equip their examples with a variety of self-destruct devices.[21]
    This may have been ameliorated by the winter of 1939, at which point a number of articles about the Norden appeared in the US popular press with reasonably accurate descriptions of its basic workings. But when these were traced back to the press corps at the Army Air Corps, the Navy was apoplectic. Instead of accepting it was now in the public domain, any discussion about the Norden was immediately shut down. This drove both the Air Ministry and Royal Navy to increasingly anti-American attitudes when they considered sharing their own developments, notably newer ASDIC systems. By 1940 the situation on scientific exchange was entirely deadlocked as a result.[21]
    Looking for ways around the deadlock, Henry Tizard sent Archibald Vivian Hill to the US to take a survey of US technical capability in order to better assess what technologies the US would be willing to exchange. This effort was the start on the path that led to the famous Tizard Mission.[22] Ironically, by the time the Mission was being planned, the Norden had been removed from the list of items to be discussed, and Roosevelt personally noted this was due largely to political reasons.[23]

    The Norden was later rejected by the RAF..

    System description

    The Norden bombsight consisted of two primary parts, the gyroscopic stabilization platform on the left side, and the mechanical calculator and sighting head on the right side. They were largely separate instruments, connecting through the sighting prism. The sighting eyepiece was located in the middle, between the two, in a less than convenient location that required some dexterity to use.
    Before use, the Norden's stabilization platform had to be "righted", as it slowly drifted over time and no longer kept the sight pointed "up". This was accomplished in a time consuming process of comparing the platform's attitude to small spirit levels seen through a glass window on the front of the stabilizer. In practice, this could take as long as eight and a half minutes. This problem was made worse by the fact that the platform's range of motion was limited, and could be "tumbled" even by strong turbulence, requiring it to be reset again. This problem seriously upset the usefulness of the Norden, and led the RAF to reject it once they received examples in 1942. Some versions included a system that quickly righted the platform, but this "Automatic Gyro Leveling Device" proved to be a maintenance problem, and was removed from later examples.

    Once the stabilizer was righted, the bombardier would then dial in the initial setup for altitude, speed and direction. The prism would then be "clutched out" of the computer, allowing it to be moved rapidly to search for the target on the ground. Later Nordens were equipped with a reflector sight to aid in this step. Once the target was located the computer was clutched in and started moving the prism to follow the target. The bombardier would begin making adjustments to the aim. As all of the controls were located on the right, and had to be operated while sighting through the telescope, another problem with the Norden is that the bombardier could only adjust either the vertical or horizontal aim at a given time, his other arm was normally busy holding himself up above the telescope.
    On top of the device, to the right of the sight, were two final controls. The first was the setting for "trail", which was pre-set at the start of the mission for the type of bombs being used. The second was the "index window" which displayed the aim point in numerical form. The bombsight calculated the current aim point internally, and displayed this as a sliding pointer on the index. The current sighting point, where the prism was aimed, was also displayed against the same scale. In operation, the sight would be set far in advance of the aim point, and as the bomber approached the target the sighting point indicator would slowly slide toward the aim point. When the two met, the bombs were automatically released. The aircraft was moving over 350 feet per second (110 m/s), so even minor interruptions in timing could dramatically affect aim.
    Early examples, and those in Navy use, had an output that directly drove a Pilot Direction Indicator meter in the cockpit. This eliminated the need to manually signal the pilot, as well as eliminating the possibility of error.
    In USAAC use, the entire bombsight was attached to a second device, the "Automatic Flight Control Equipment" (AFCE), an autopilot system. The AFCE could be used during the flight to the target area through a control panel in the cockpit, but was more common used under direct command of the bombardier. The AFCE sat behind and below the Norden and attached to it at a single rotating point. On the bomb run, the bombardier would first rotate the entire Norden so the vertical line in the sight passed through the target, and then clutched in the AFCE. From that point on, the AFCE would attempt to guide the bomber so it followed the course of the bombsight, and pointed the heading to zero out the drift rate, fed to it through a coupling. The AFCE was another reason for the Norden's accuracy, as it ensured the aircraft quickly followed the correct course and kept it on that course much more accurately than the pilots could.
    Later in the war the Norden was combined with other systems to widen the conditions for successful bombing. Notable among these as the radar system called the H2X (Mickey), which were used directly with the Norden bombsight. The radar proved most accurate in coastal regions, as the water surface and the coastline produced a distinctive radar echo.[39]

  4. #19

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    Click image for larger version. 

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    This one?

  5. #20
    Senior Member Steak-Sauce's Avatar
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    Quote Originally Posted by Scorchio View Post
    Pic of a RAF Coastal Command, Fortress Mk.IIa with a 40mm Vickers "S" in the nose

    The Vickers S used 15-round drums when it was fitted to Hurricane Mk.IID so I assume the same was true for the Fortresses that carried it.

    The 57mm would be a Molins 6-pounder Class M, as was fitted to the Mosquito FB.XVIII 'Tsetse' variant, which did have an autoloader
    Awesome picture and information, Scorchio. Many thanks!

  6. #21
    Moderator James's Avatar
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    Quote Originally Posted by MeiJoa View Post
    Click image for larger version. 

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    This one?
    I believe that's a KG200 B-17.

  7. #22
    Senior Member Euroamerican's Avatar
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    Study up on 100 Group. They flew all kinds of interesting stuff in their special ops activities.

    I have a book, "Confound and Destroy", or something like that.

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