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Old Jun 04, 2013, 08:00 PM
twiglet123 is offline
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Ballast tank questions

Hello boys and girls, next step on my build a sub plan is to make the ballast tank.

It's going to be a pressurized tank that fills from a windscreen washer pump.
The pump will fill the tank pressurizing the air inside it then to release the water a valve will simply be opened allowing the water to be forced out by the built up air pressure.
I plan to build the tank from a strong piece of pvc drain pipe with two lexan endcaps held in place by threaded rods as per the masterpiece done on ms paint below.

just a few questions before pushing forward.

First, does the method of sealing this look like it will work or are there any obvious holes in this plan I haven't foreseen?

Next will the rubber be enough or would it be better to have some sort of epoxy for sealing too also any tips on the kind of rubber to use?

Are there any rough recommended sizes of ballast tank for different sizes of submarines out there?

Also I've spotted a potential issue pictured below, if the sub dives at a particular angle and I open the valve when the outlet pipe isn't covered by the water i can see the tank just emptying the pressurized air but leaving the water inside it with no way to get the submarine back up to surface, are there any standard ways of getting around this?

Any suggestions, recommendations or advice much appreciated

All the best
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Old Jun 04, 2013, 09:35 PM
derk is offline
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perhaps use a weighted tube end inside the tank like the airplane fuel "clunk tanks"?
Old Jun 05, 2013, 06:35 AM
Subsonic Mike is offline
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I am using the same method of sealing the WTC on my sub, so you should be fine.
One suggestion though is to only have 3 or 4 threaded rods, 7 seems overkill and a pain to undo to access the insides.

Old Jun 05, 2013, 08:41 AM
twiglet123 is offline
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Thank you man, you don't have any photos lying around of your tank do you for refference?

Also what rubber did you use to seal it?
Old Jun 05, 2013, 09:15 AM
Subsonic Mike is offline
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The WTC isn't finished yet but in we (me and my dad) more or less copied the design from Norbert Bruggen's book. We also asked at submarine meetings on how to design a cylinder.

I will have to get back to you on the rubber and pictures because i'm going out soon.

You might want to think about getting the book, its quite old but very very detailed and just a great book.
book link

Old Jun 05, 2013, 11:03 AM
POLARISDAVE is offline
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Blood pressure cuff

I use a blood pressure cuff under the wtc inside the hull and a water pump from subworks mounted inside the WTC. I pump water in to dive and run the motor back wards to pump water out to surface. as a back up I have a 2nd cuff mounted below the deck and a air pump in the WTC to inflate the cuff in the event that pumping water out wont surface the sub. I will testing it next weekend and I hope to have a video of it.

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