[PSUBS-MAILIST] Dome Calculations

["James Frankland" <james@guernseysubmarine.com>]

Hello Everyone

Progress on my sub has been slow recently, but i have managed to get a few things done including a change to the possible design for the removable front dome mounting system that i am adding instead of the 15" flat port specified on the plans.

I have made some changes to my original design as a result of reading Staichows book and with some advice from members of the group.

http://www.guernseysubmarine.com/index_files/Page12229.htm

I would really appreciate if you could take the time to have a look and let me know what you think of this idea.

Points to note\questions.

1.  The "O" ring groove has gone and been replaced with a 1mm bead of sikaflex sealant.  Bearing in mind the idea of this design change is so the dome can come out in an emergency, do you think this amount of sealant will stick it permenantly and prevent removal, even with a good kick from the inside?  Could make it thinner, 0.5mm?

2.  The inside diameter of the ring meets exactly the inside diameter of the dome.  (The 32mm bit on the second picture).  Should it be a bit larger?  35mm?

3.  I do not have the ability to do FEA on this ring, so based on the "rule of thumb" that says you should replace the amount of material you remove, i have calculated volumes of the ring and the removed piece.  The figures are shown at the bottom of the page.  The endcaps are spun and thicker than specified on the plans.  13mm at the rims ranging to about 10mm at the centre.  So, exact calculations for volume of this are difficult.  If based on the worst case scenario of 13mm all over, the volume of weld in ring does not cover the "rule of thumb".  Should i add an extra 10mm to the thickness of the ring, bearing in mind the endcaps are already quite a bit thicker than needed.

Does that make sense?  I've not done one of these before so i think its better to ask silly questions now and avoid mistakes or accidents in the future.

Again, this is still just an idea at this stage and could all change, depending on how things turn out.

I appreciate any advice, good or bad.

Regards
James