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Thread: 2" WW2 Mortar

  1. #11
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    Two variants of the Abram Games "blinds" posters (courtesy IWM online poster collection), each including a 2" HE mortar round. The message - if not the actual posters - was supposedly widely circulated, but unfortunately not always observed, especially by children.
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  2. #12
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    Those two pages make interesting reading. I'm surprised the victim of 4171; 69 Grenade, Kicked Blind, lived to tell the tale. The 77 Grenade claimed more than its fair share of victims and surprisingly, they appear to have survived their phosphorous burns. Presumably 4186 is a fatal accident as opposed to suicide, if it were the latter I would have expected an officer to use his issue revolver.

    TimG

  3. #13
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    Thanks so much again; all this is building a clearer picture in my mind. I now have a theory how the boy exploded the mortar.

    After taking the 'blind' it home a witness saw him tamper with it in the street; he'd taken off the windshield cap then removed the striking pin ("he pulled out a screw with a pliers and a spring came out..."). He then inserted a screwdriver into the hole left by the striker pin. In effect, the screwdriver's sharp point became a replacement striking pin. This is the "hole" the witness referred to. As you know, the hole is directly above the various charges and he might have punctured the sealed tin that contained the phosphorous ("Then he put a screwdriver in a hole in the bomb an white powder came out".) At some stage poking about in the hole detonated the round. What I don't quite get is why did he not touch the septum first - the charge immediately below the sharp point of the striker? This would be sitting on top of the CE charges?
    Regards,
    Rondee

  4. #14
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    Thanks so much. I've been looking for warning posters the schoolboys might have seen without luck until now! Wonderful - a very big thanks.
    Rondee.

  5. #15
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    If he took out the striker then he would have hit the det cap unless it stuck in place to the side which caused the blind in the first place. Directly underneath the det cap, in the correct position the point the firing pin would strike, is the narrow stem of CE in the middle of a large thick disc which is too thick to poke a hole into with a screwdriver. To get at this small stem of explosive he would have to penetrate the metal tin disc that covers the thick disc, once into that the bursting charge but to get into the main charge he would have to penetrate a thick metal cup that holds the bursting charge of the fuze. In operation the det cap bursts into the thin disc to set of the small stem into the next bursting charge. He could have penetrated the tin disc while the det cap was to the side thus revealing the white CE normally light yellow and then disrupted the det cap so it sprang in line with the CE stem so the next time he poked with a screwdriver it set of the det cap.
    Last edited by BMG50; 28th March 2019 at 09:51 AM.

  6. #16
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    Thanks for this. In the back of my mind I wondered what caused it to be a blind.

    If I get this right; are you saying that the round has a 4-stage detonation process and that the 1st det cap wasn't under the striking pin, thus causing the blind? Can I paraphrase what you wrote and perhaps you can correct me.
    The screwdriver was inserted into the sealed tin of the 2nd stage fuse. He punctured this tin and white/yellow powder came out. For this white powder to come out, he obviously withdrew his screwdriver. When he inserted the screwdriver again the 1st det cap had somehow moved into its correct position over the punctured tin disc and oblivion...
    Kind regards,
    Rondee.

  7. #17
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    I am only assuming what could have happened, the mortar round could have grazed a bush so the wind shield is not crushed enough for the striker to set off the det cap. When you mention the sealed tin i mean a tin disc that sits onto of the thicker metal disc with a small hole in the middle that contains a small amount of CE the septum. To get at the white powder you mention, this small round hole would be the only way for such a substance to come out, hence the det cap that would be in its way, if the striker and det cap worked properly ie moving in alignment, so it would seem the det cap was to the side jammed in place until the boy dislodged it and then poke the screw driver in.. Not that you may not want to, it would be best to examine a deactivated one close up rather than a drawing as then it would make sense what could have happened.

  8. #18
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    What you say makes good sense. There's some evidence in the coroner's inquiry that a mortar blind was found in a river. The area was also covered in thick gorse and bracken. The 2" mortar has quite an ingenious fuse mechanism. I'm afraid I know nothing about why it needed a 4-stage detonation process.

  9. #19
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    First the cap is set off by the striker 1, which sets off the septum 2 which then sets off the CE pellet 3 which exploded into the main charge 4 setting that off. You need a detonation to detonate explosives, a simple det cap won’t do this.
    On a WP round there is no main charge just a small sealed tin can of white phosphorus, which is activated when exposed to air by the exploding CE pellet. The CE pellet when it is set off is powerful enough to blast open the bomb casing and tin like a split banana spreading WP all around. The CE pellet alone would kill or seriously injure you without any additional explosives. A live fuze alone is a dangerous thing. I do have a picture of the remains of a exploded WP case which the CE pellet alone caused, so you can see the destruction it would cause to finger arms etc.
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    Last edited by BMG50; 30th March 2019 at 01:45 PM.

  10. #20
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    I'm having an education!! Thank you so much for this. There's one other aspect of the fuse I need help and it's the type of HE mortar that was tampered with on March 1945.

    I have a diagram of the Mk 1 161 and it shows a hole to the left of the striker that has unimpeded access to the det cap directly below but other types have this hole blocked off. (I'm sorry I can't insert a picture?) Would you have any idea as to the type of mortar that would be used in training in March 1945 that have this hole open or closed.

 

 
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