Re: [PSUBS-MAILIST] Pressure hull

["Thijs Struijs" <thijs-struijs@planet.nl>]

Thanks for your reaction Ian,

It was your idea ideed (may 2002) that made me think. I don't trust my own
welding so i will have a professional do the work. Just welding 2 endcaps
together is a nice and simple thought. Most personal subs have 2 endcaps
with a lot of complications between them. So why not eliminate the middle
part and stick to the endcaps? As was mentioned before (by you and Carsten)
the endcaps in a K-sub have to be thicker than the cilindrical part. This
limitates the max. diving depth. You will very fastly reach the point where
the sub becomes so heavy that it won't float anymore or you wil have
problems to keep it stable without the use of sintactic foam. Another
positive point on the design is the relative great height insite compared to
the weight. It gives you a chance to built a very small and light sub with
relative comfort.

Greatings,

Thijs Struijs

----- Original Message -----
From: "Ian Roxborough" <irox@ix.netcom.com>
To: <personal_submersibles@psubs.org>
Sent: Sunday, February 09, 2003 6:16 PM
Subject: Re: [PSUBS-MAILIST] Pressure hull


>
> Hi Thijs,
>
> this is an interesting design.  I tried working out something similar
> (a two man fish shaped sub), my main conclusion was that an end cap
> sub isn't very scalible for depths.  Going by the ABS standard, if I
> was to double the thickness of the pressure, I got an extra 15 feet
> of usable depth.  The main reason for this is that the main surfaces
> of the sub have a curve radius far larger than the submarine.
>
> Still, even with the depth limitation, it's probablya good design
> if you're not going for a deep diving sub.
>
> Ian.
>
> On Sun, 9 Feb 2003 18:02:15 +0100
> "Thijs Struijs" <thijs-struijs@planet.nl> wrote:
>
> > To all,
> >
> > I would like some reactions on a drawing i made a while ago. You can
find it at:
http://www.prismnet.com/~moki/20030126.073208/doubleXendXcapX.jpg .
> > The idea is to construct a very simple pressure hull out of two
torispherical endcaps. The conning "tower" is made out of a standard line
pipe with a little overdimensioned wallthickness and the smallest possible
diameter. The endcaps are made with a small cilindrical section on it but i
am afraid that the tower will intersect with the torispherical part.
> > In order to keep it simple i chose a very common steel for the endcaps.
It is P265GH (yield strenght 265 n/mm^2, 38500 psi, tensile strenght 410
n/mm^2, 59500 psi). This is an "off the shelf" material at Afflerbach, the
german manufacturer. I think you could call it soft boiler steel.
> > To calculate the strenght of it (apart from the conningtower and
viewports) one can use the formulas for a sphere, using the dishing radius
of the endcap (in this case 1040 mm). Maybe it is my age, to much alcohol or
lack of intelligence but watever method i use (ABS, Lloyd's or an old
pressure vessel codebook) i get different outcommings. Can anyone of you say
something sensible on this? I am considdering a wallthickness of 12 mm,
divingdepth 100 mtr?
> > If it is ever going to be build it will be tested unmanned to a depth
50% more than its safe working depth. Should it collapse i will hold no one
responsible for that. So please be free to give your advise.
> >
> > Thank you very much,
> >
> > Thijs Struijs
> >
>
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