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Old Jun 08, 2013, 04:13 PM
twiglet123 is offline
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Current progress on my ballast tank and questions

Right here's the current progress towards my basic model submarine ballast tank (apologies for large dark and dingy photos).
I've got the rough idea ready and have started producing the endcaps though I want some advice before I carry on to the next stage.

First of all Iím a little worried about the seal size.

As you can see above the wall of the pipe is kinda thin (about 3 mm), the pipe can take the pressure but it gives very little surface area for the rubber between the lexan cap and the pipe to hold an airtight seal.

Iím going to try the method drawn below but would appreciate advice on whether Iím about to spend a lot of time on something that wonít work.

I do intend to cut the pipe down into sections of 30cm (30 at the front and 30 at the back for radio gear, servos, motors etc and 30cm in the middle for the tank).

The pipe is 4 inch wide (roughly 10cm diameter) so this aught to give me very roughly a 3 litre tank although the pressurized air will take up some space but none the less it aught to be enough to bring the sub under the water.

Sooo thoughts sugestion, point and laugh
over to y'all
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Old Jun 09, 2013, 09:17 PM
eRaptor is offline
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Here is a suggestion: can you find nesting tubes one size larger and smaller?

If so, you could cut short lengths, say 1 cm or so, and glue those to the ends. That will result in a 9 mm wall thickness. Which may be more than enough to give you a good seal.
Old Jun 10, 2013, 10:07 AM
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Why is there a continued preference for cylindrical pressure compartments which require complete removal for internal adjustments and push-pull control rods instead of rotational through-hull shafts? Sure rectangular tanks are not that hard to fabricate and in-boat adjustments are now simple. A removable lid for major adjustments and small hatches for switches and charge plugs.
Old Jun 10, 2013, 02:42 PM
Sub culture is offline
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You can put rotary control seals on a cylinder too. Cylindrical enclosures are much better at resisting water pressure, and are easier to make watertight. How many full size subs do you see with anything other than a cylindrical or spherical pressure hull. the only one I recall is the Brandtaucher, and that sank!
Old Jun 12, 2013, 09:30 AM
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Though in all fairness, a compound pressure compartment also works: I have used part of the hull for one wall, and then put in semi-circular ends and a flat top. Of course, this is not removable, but is it is easy on space requirements.

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