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Thread: What was an ib ("x")

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    Default What was an ib ("x")

    I recently had a look at the Bomber Command Loss card for my uncle’s aircraft. In the bomb load section, it has 88 x 30 IB, 900 x 4 IB and 90 x 4 IB (“X”). I assume IB means incendiary bombs but does anyone know what type of incendiary IB (“X”) were?

    Douglas

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    Hi Douglas,
    Not "IB" for Incendiary Bomb, but lb as in pound weight, they were carrying 88 x 30 lb incends, and 900 x 4lb incends plus 90 x 4lb "x" for which i don't know what the "x" stands for.
    Alan

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    Hi Alan

    Being of the older school I had thought it may have been lb (pound) but it is definitely a capital I

    Regards

    Douglas

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    Hello

    In this case IB stands indeed for incendiary bombs, and the 30 lb and 4 lb are definitively incendiary bombs weights.


    They were of hexagonal shape, and sometimes grouped in larger containers. I'm not 100 % sure that these were the Small Bomb Containers (SBC), or another variant.

    A few years ago I researched also the meaning of "X", which I found, but since then, I've forgotten exactly. Hopefully someone will come up with the explanation in less time that I'll have to re-find my answer...

    Have a nice sunday

    Joss

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    Hi Joss

    Thanks for your reply. I hope you can remember what IB ("X") was.

    Regards

    Douglas

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    This usually meant Group X relating to the classification and grouping of explosives.

    Incendiary were Group XI or Group XII

    The Group relates to the mix and match combination what can be loaded or stored safely without risk of the entire load/store being set off without it being primed.

    Regards
    Ross
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    Ross

    Thanks for the update and information.

    Regards

    Douglas

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    Hello everybody.

    IIRC the X type was the explosive variant of the ordinary 4 lbs incendiary...

    Can't download the file right now, but there should be an explanation in:

    www.dtic.mil/dtic/tr/fulltext/u2/a474302.pdf

    Regards,
    Hans

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    Thank you Hans and the rest of the forum who have replied to this thread.

    Douglas

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    Hi Douglas - There's a section on this in AIR 41/81 - the AHB 'Armament Vol 1' (1952).

    The 'X' is a 4lb I.B. fitted with a capsule of gunpowder (some with delay fuzes) to deter fire wardens. There was a Committee set up between the wars dedicated to working out the best means of starting fires. It learnt a lot from the Germans in 1940/41. In January 1943 it began experiments in Woolwich with 'I.B. Cottage' to evaluate how rooms burnt.

    One discovery was 'flash over', when a room switches from a space containing a number of fires to a single burn, with everything in it generating heat rather than soaking it up. It took 15-50 minutes for a typical room to reach 'flash over', when the temperature in the centre of the space would jump from 200-400 degrees C to around 1,000 degrees C.

    At 400 degrees, an amateur with a stirrup pump could apparently put the fire out. at 1000 degrees only the proper fire services with high pressure hoses could defeat the fire. The role of the X type I.B. was to deter fire wardens so that 'flash over' would occur.

    Cheers,

    Richard

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