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Papplewick Pumping Station SUBMARINE Day. 31st March - 1st April 2024.




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    bladder systems


    Posts : 91
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    bladder systems Empty bladder systems

    Post  SimonH Sun Dec 05, 2021 8:52 pm

    Hi folks, 'm starting to think about the bladder now I can see the end of the WTC with its peristaltic pump so and thinking about the bladder.
    A lot seem to use a cut down cuff from a blood pressure meter, but since I new a longer thiner bladder I think to fit I was thinking about a length of bicycle inner tube. In theory the pressure differential should be zero apart from possible over inflation at the surface as far as I can see.
    I don't want it too long or I can see the same stability problems as with a long thin water ballast tank, but removing the valve core and with and adapter it should connect quite nicely with the air pump.
    Originally I intended to have a seperate air reciever but for simplicity I might just use the WTC which as it is large vs the bladder the change in pressure should not be too great. I'm a bit bothered that the silicon tube type control rod seals might act as a valve venting air out or that excess pressure might pop out the shaft seal (though it will have a keeper fitted) but I've not seen that mentioned as problems anywhere.
    In theory as the WTC pressure increases the external pressure should also increase as the boat dives, but I doubt they'll keep in step!
    Has anyone tried an inner tube as a bladder?
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    bladder systems Empty Re: bladder systems

    Post  Tom(ADMIN) Mon Dec 06, 2021 11:34 pm

    It has been done. The pressure you build up is minimal, however, make sure your endocarps are secured somehow. Those can pop off.

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    david f
    david f
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    bladder systems Empty Re: bladder systems

    Post  david f Sat Dec 11, 2021 11:24 am

    Bike inner tubes have been used in the past (but not by me I have only used medical type bags.)

    The problem was, I think, sealing the cut ends.

    I happened to see that Norbert Bruggen offers a bag (which I think you can cut and glue). It is charmingly called a Gummisack in German! His product may give you some ideas.

    I think I saw elsewhere ? that you were thinking about using a float and fishing line distress indicator. I am feeling my age because I remember thinking, several decades ago, that was not a very good  idea (float buoyancy, friction, water depth, angle of wreck) hence the various types of Pinger.

    However I seem to be the only person using these bladder systems 1f626 and most people in model subs seem to only sail in clear, shallow water! Which seems a shame because it is so rare (in the muddy UK anyway.)

    Lovely work on your "WW2 mini sub" by the way bladder systems 1f603


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    bladder systems Empty Re: bladder systems

    Post  tsenecal Tue Dec 21, 2021 3:35 pm

    being an owner of one of norbert's delta submersibles, i am quite familiar with his pump/bladder systems. the bladder is made out of a sheet vinyl that is cut and folded, with a plastic tube (think fish tank filter/pump tubing) glued together with the black rubbery CA glue. I have found functionally identical vinyl sheet on McMaster/Carr's website.

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