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RE: [PSUBS-MAILIST] OSS (Pressure hull)

Here's a typical lesson I learned when I went from a submarine project in my CAD software to a submarine project in my garage. My original design called for an endcap on the stern, I think it was 30.5" in diameter or something like that. When I went to order it, they quoted me $4,160 for a single endcap, of which $4,000 was the setup cost and $160 the production cost. The $4,000 was because my dimensions were not standard. But if I adjusted my design by half an inch, the cost was just $160.

You'll find standard dimensions in references like the Pressure Vessel Handbook (or some European equivalent). It doesn't hurt to talk to the manufacturers, they are very helpful indeed. After all you're the customer and they want to sell.

If someone on the list can run a finite element analysis on the design with the viewport seats through the endcap flanges, and they can be designed with a good safety margin, I'm all for a vertical saucer design. Voila, an instant pressure hull.

rgds,

Alec

-----Original Message-----
From: Thijs Struijs [mailto:thijs-struijs@planet.nl]
Sent: Tuesday, February 11, 2003 4:43 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] OSS (Pressure hull)


Pierre,

Good idea for the OSS pressure hull.

These endcaps can be bought. There are probably some standard dimensions
because they need special tools to make them. At this moment i did not
contact any manufacturers at all because when i do, i want to know what i am
talking about. You don't get a second chance meeting someone for the firts
time. I do know there are standard relations between diameter and radii. For
more information you can have a look at these websites:

http://www.bakertankhead.com/products.htm (USA)

http://www.afflerbach.de/html/default.htm (Germany)

http://www.antonius.nl/antonius/home/products.asp?lang=English (Netherlands)

Greetings,

Thijs Struijs



----- Original Message -----
From: "Pierre Poulin" <pipo305@hotmail.com>
To: <personal_submersibles@psubs.org>
Sent: Tuesday, February 11, 2003 1:47 PM
Subject: RE: [PSUBS-MAILIST] OSS (Pressure hull)


> Hey, OSS group!
>
> How about using that hull for the project? It look simple and could have
two
> persons side by side. Like the Cousteau thing.
>
> Also, are those end-caps available or do you have to build them from
> scratch?
>
> Bye, Bye!
>
> Pierre Poulin
> "I'm skating instead of diving!"
>
>
>
>
> >From: "Alec Smyth" <Asmyth@changepoint.com>
> >Reply-To: personal_submersibles@psubs.org
> >To: <personal_submersibles@psubs.org>
> >Subject: RE: [PSUBS-MAILIST] Pressure hull
> >Date: Mon, 10 Feb 2003 16:42:50 -0500
> >
> >Thijs,
> >
> >I love the simplicity of a hull made from simply two endcaps. I thought
> >mine would be simple enough as it is basically a reinforced pipe, yet
> >welding two elliptical heads like this would have saved me at least 6
> >months work, or more. The reason is you would not have to contend with a
> >cylinder which is never quite round when you receive it, and getting
round
> >rings into an oval cylinder was the hardest thing on the whole project so
> >far. The part I would worry about is that you have inserts that cross the
> >join between the two halves. Not that it can't be done, but it introduces
> >what to me at any rate are unknowns in the stress calculations. I try to
> >use only things that I can calculate.
> >
> >Besides Cousteau's saucer, there is another sub out there based on this
> >principle of joining two elliptical heads. Unfortunately I can't recall
its
> >name, but I remember seeing a picture of it online somewhere, hanging
from
> >a crane and painted white and orange. If anyone can recall the sub I'm
> >referring to, you might find it a neat idea. What they did was incline
the
> >"saucer". It was oriented in a horizontal plane like Cousteau's, except
it
> >was also inclined "up hill" about 30-45 degrees. While this might seem
odd,
> >they also had an exostructure that faired it. The lower head had two
bubble
> >windows facing forward, but as the saucer was inclined, these two windows
> >did not have to cross the weld between the two heads. The occupants
> >traveled lying down and the hatch was of course on the upper shell.
> >
> >rgds,
> >
> >Alec
> >
> >
> >  -----Original Message-----
> >From: Thijs Struijs [mailto:thijs-struijs@planet.nl]
> >Sent: Sunday, February 09, 2003 12:02 PM
> >To: PSUBS
> >Subject: [PSUBS-MAILIST] Pressure hull
> >
> >
> >
> >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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