The Legendary Avro 6 Bomb Carrier for the Mosquito

Discussion in 'Aviation' started by wuzak, Aug 9, 2014.

  1. wuzak

    wuzak Well-Known Member

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    For many years I have seen rumours and descriptions of a bomb carrier for the Mosquito which could carry 6 250lb or 6 500lb stores, usually associated with Avro.

    And here it is:

    Twin 1000lb Carrier 800.JPG


    Well, actually it is not. This picture is from a file in the National Archives of the UK, AIR 14/2707 Mosquito Carriers - Special Types.

    It is, in fact, two standard Avro 250lb/1000lb bomb carriers attached to a modified Mosquito 4000lb carrier which enables a bulged bomb bay Mosquito to carry 2 x 1000lb Target Indicators (TI) or 2 x 1000lb MC/GP bombs. These carriers were developed originally by a couple of squadrons in 5 Group and 8 Group to use 1000lb stores - principally the 1000lb TI. There were two main TIs during the war - 250lb and 1000lb, but no 500lb TI. Correspondance relating to these carriers started in mid 1944 and continued into late 1944/early 1945.

    A few months earlier a 4000lb carrier was adapted to carry a single 1000lb TI (same size as 1000lb MC bomb) in a standard Mosquito bomb bay. Some trimming of the bomb bay door stiffeners was required to give adequate clearance. This still only amounted to a 1000lb load.

    In early-mid 1944 there were moves made to better utilise the bulged bomb bay in aircraft performing target marking. It was deemed poor economics to send a Mosquito with the larger bomb bay to target carrying a load of 4 x 250lb TIs. A solution that was tried was the adaptation of a bomb beam from a Vickers Wellington. The description is of a double beam (presumably that means it could hang bombs on both sides) which was shortened, with additional stiffeners.

    The Wellington bomb bay
    [​IMG]

    A meeting was held at RAF Upton in June 1944 to inspect the installation of a modified Wellington bomb beam fitted to a Mosquito. The meeting notes show that there were some minor revisions to be done to the installation. The installation achieved the goal of carrying 8 x 250lb TIs. Other loads were discussed:

    8 x 500lb MC bombs - de Havillands thought that the all-up weight would be too high and the CoG too far rearwards for this to be viable (this may be for a B.IV with bulged bomb bay, it isn't clear).
    4 x 500lb + 4 x 250lb bombs - which was to be forwarded to de Havillands for their consideration.

    The last page in the file was a letter from AVM D. Bennett, 8 Group, titled "Increased Stowage for TIs in Mosquito Aircraft" and dated 27 April 1944. The two options suggested were the Wellington beam option, as above, and the development of a new type carrier which could only carry 6 250lbb TIs but would require less modification to the aircraft. There is no indication as to whether the second option went any further than that, but that could be the basis for the "Avro Carrier".
     
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  2. vikingBerserker

    vikingBerserker Well-Known Member

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    The plane never ceases to amaze me, great post.
     
  3. wuzak

    wuzak Well-Known Member

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    Another document I have recently acquired is about trials of the Norden bomb sight in the Mosquito during July 1944.

    The conclusions were that the bomb sight was well made, was easy to learn how to use, but was more complicated in operation than the British Stabilized Automatic Bomb Sight (SABS).

    There were tactical limitations to the use of the Norden. A bank of 18° would topple the gyro - not an issue in a B-17 and the way they were used, but not good for a type such as the Mosquito. Furthermore, in the Mosquito installation a bank of 5° would make it impossible for the bomb aimer to sight through the telescope.

    It was noted that of 25 test bomb runs at 15,000ft in only 15 was it possible to aim and drop bombs due to the weather. The Norden required a long straight run up to target with little or no cloud in that time.

    During the tests it was found that it was difficult to level the gyro in flight due to fluctations of the bubbles in the level gauges. It was thought that this was due to slight instability of the Mosquito, no issues having been experienced in the similarly sized P-38. The experience was that the sight would often need to be releavelled, after which the crosshairs would invariably be off target.

    The Mosquito used was a B.XX, whose CoG was further aft than normal, which may have contributed to the instability experienced.

    Bombing results were poor, with an average distance from target of around 500 yards.
     
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  4. Milosh

    Milosh Well-Known Member

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    Great find wuzak.
     
  5. Airframes

    Airframes Benevolens Magister

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    Good stuff, and useful for modellers too.
     
  6. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Did the document say what speeds they were bombing from?
     
  7. Crimea_River

    Crimea_River Well-Known Member

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    Great info. Hard to understand how a Mosquito would be more "unstable" than a P-38 though.
     
  8. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    "The Mosquito used was a B.XX, whose CoG was further aft than normal, which may have contributed to the instability experienced."

    Anytime you fly with an aft center of gravity, stability will decrease.
     
  9. Capt. Vick

    Capt. Vick Well-Known Member

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    Great post!
     
  10. wuzak

    wuzak Well-Known Member

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    No, it did not. Which is surprising.

    You would think that would be a vital piece of information for setting up the sight.
     
  11. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Exactly!

    I doubt you could do a bomb run faster than 150 mph. To me this is a waste of assets to fly a high altitude mission in this capacity. The only way this could have worked is with zero fighter opposition.
     
  12. wuzak

    wuzak Well-Known Member

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    #12 wuzak, Aug 9, 2014
    Last edited: Aug 9, 2014
    Was there a limiting speed for the Norden bombsight? Surely B-17s flew faster and bombed at a faster speed than 150mph (unless you are talking IAS)?

    The planned trials for the Mosquito were to be from 25,000-30,000ft but the only ones completed were at 15,000ft. My earlier post mentioned a July date, but that was the meeting for the inpection of the sight installation. Actual bomb runs were started in late September, and the report dated November 1944.

    Another thought I had was the connection between the aircraft and the bomb sight. In the B-17 he bombadier controlled the aircraft with the sight via the auto-pilot system. I doubt it was set up that way in the Mosquito, the bomb aimer having to call corrections to the pilot.

    But what about the P-38? Did that have any auto-pilot system, or would it have operated in a similar manner to the Mosquito?
     
  13. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    IIRC The normal bomb run was at about 150 indicated (maybe a bit faster)
     
  14. wuzak

    wuzak Well-Known Member

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    That would be a bit like suicide for an aircraft like the Mosquito.

    IIRC, the Mosquito's bombing limitation was 300mph IAS.
     
  15. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    #15 FLYBOYJ, Aug 9, 2014
    Last edited: Aug 9, 2014
  16. wuzak

    wuzak Well-Known Member

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    Interesting that they introduced the Droop Snoot to improve accuracy but then, if I am reading that link correctly, they all drop their bombs automatically when the Droop Snoop bombadier releases his.
     
  17. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Exactly, and I believe from altitudes at 20K. Later in the war that's the way the heavies did it with a bombardier in the nose and a "toggle" in each of the remaining aircraft.
     
  18. Crimea_River

    Crimea_River Well-Known Member

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    In conversations I had with a veteran observer in Mosquitos with 627 Squadron, he told me that they dropped their TI while doing a shallow dive. I would think the speed was faster than 150.
     
  19. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    When operating conventionally, not while using a Norden bomb sight
     
  20. Crimea_River

    Crimea_River Well-Known Member

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