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Re: [PSUBS-MAILIST] hull and glass
Mike,
There is no "good" thickness. You need to
design in the REQUIRED thickness according to your calculations.
Not all parts of a sub are the same
thickness. I'm building a K-350 and it has a .250 inch thick hull with
.375 thick end caps. The conning tower is also .250 inch thick, but the
transition collar that joins the conning tower to the hull is .750
thick. It's an area of high stress. K-350 is tested at 500 feet
and is man rated to 350 feet. I must add, the hull has internal framing
also. That's an important part of the structure. If your thinking of
1000 feet, all of this changes drastically.
As far as what type of steel, A-516 grade 70
is recommended because of it's ease of welding and it's pressure vessel
quality. I believe it also has some properties that make it better for
cold water situations, but don't quote me there.
Plexiglas thickness also depends on the
application. It depends on the viewport diameter and the subs depth
requirements. My 16 inch viewport is 2 inches thick. The overall
diameter is the lens is sixteen inch but the actual view port diameter is about
12 inches because of the large backup lip required to support the Plexiglas
lens. All of this, and far more, is covered in a publication called PVHO,
Pressure Vessel for Human Occupation. I suggest you get a copy if your
designing from scratch.
There is another way of building a sub if your not
really set on YOUR OWN design. Purchase a set of K-250 or K-350 plans and
alter what you feel comfortable with from there. Believe me, you'll have
plenty of chances to design in your own options but you also have the peace of
mind that what your building has been tested and proven many times.
Don't get in over your head designing something
you won't feel safe in. You will have a bunch of money invested in a
sub by the time your finished. It makes no sense to build something
that you can't use, or can't sell to anyone late on. Even
worst, it may get you killed. Do your homework.
Again, good luck, Dan H.
----- Original Message -----
Sent: Monday, March 17, 2003 4:09
PM
Subject: Re: [PSUBS-MAILIST] hull and
glass
Thanks Dan I appreciate the help I will have to check the archives for
further info, is there a good thickness for the steel ? the plexi-glass ?
Thanks
"Dan H." <JMachine@adelphia.net>
wrote:
Mike,
A thousand feet is deep for many PSUBS.
My material of choice is "tried and true" Steel. Pressure vestal
quality steel. It's easy to find and not to bad to work with.
There's a lot of information available on it too. The extra weight in
a sub isn't usually a really big deal since your building it to sink
anyway. If it doesn't weigh it's weight in water displaced, you
built a surface boat.
To build a steel sub to go a thousand feet of
depth though you may be reaching the upper end of weight to PSUB
size ratio though. It depends on the overall displacement of the
sub your building. With steel, you MUST know how to weld. Even
if you farm out most of it, there will still be many small welding jobs that
you have to do along the way.
Plexiglas G is the material of choice for
viewports. It too is easy to come by and work with. Do some
research in how to machine and anneal it though. There is good data
available on it also.
You may consider designing 2.5 safety factor
for a collapse depth. You should do an unmanned test to 1.5-2.0, just
to prove the hull.
I don't know about fabric over any kind of
frame. It's not my area.
You will probably have to have frames in your
hull to keep roundness no matter the material. Your hull must be
concentric. You can't have any flat spots or even out of
roundness. You can't be out of round anymore then half the hull
material thickness.
Good luck,
Dan H.
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