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I just came up with another interesting idea.
We all know the basis behind the autoclave right? An autoclave is
basically a huge PRESSURE VESSEL with a heating element inside. So, why
re-invent the wheel? Simply reverse the thinking:
Prefab D.O.T. pressure vessels usually have the
stringers on the outside, this is good. They also come with endcaps.
Simply have one made that can handle internal pressures with temps 250F+. (most
chemical storage tanks meet this I presume).
Next, we install a compressor at one endcap.
Then, a power supply with a heating element on the other, that runs the length
of the cylinder. Or better yet, if you can, install them both on the same
side.
The CF is then laid on the INSIDE of the tube,
closed up, and pressure cooked. The autoclave itself is the outside
shell of the sub.
Once you've laid as much CF as you want, you remove
the compressor and the heating element and voila - strongest personal sub. in
the world. You could also have the heat source on the OUTSIDE, but this
doesnt guarantee uniform temp. dispersal.
This technique makes simple sense to me,
because the high internal pressures are pushing the CF to the shell while
curing, as well as eliminating the voids WITHIN the CF and between it and the
shell.
Only other thing I could think of is maybe using
the shell to lay some kind of thermoplastic, probably on the outside. The
shell could be heated to accomodate it and then cooled to solidify
it. Thermoplastics are actually going to put autoclaves out of
business eventually, so they say.
Shawn
----- Original Message -----
Sent: Monday, November 07, 2005 8:44
PM
Subject: Re: [PSUBS-MAILIST] Composite
Hull Calculations
Yah, the more I dig into composite sub
construction the more I realize how cutting edge it is. Hell, the Navy
is BARELY scratching the surface with this stuff. There ARE autoclaves
big enough to anneal a pretty large submarine (I think the biggest U.S.
autoclave is like 30ft x 75feet). The biggest expense here seems to me
in transporting the vessel and fabricating a jig. Having something
sit inside a pressure-cooker cant be all that expensive can it? Also,
everything would have to be pre-designed before you lay the CF, that is,
anything that's going to lie outside the normal geometry of the pressure
hull. Very complex, just in the design phase... but once designed, it's
conceivable the construction wouldnt be too difficult - MUCH easier then
working 1/2" steel. In reality, it IS wrapping a pressure vessel in CF;
namely a 1/4" D.O.T. vaccuum tank; another option is chemical storage
tanks. Without the wrapping or going to 1/2" steel it's just not worth
it designing anything that big and expensive, as you cant go very deep, even
with stringers every foot.
So like said before, getting the voids out of the
CF is the "sticky" part... hehe Laying up the CF is tough too and
you'd probably need laser guidance and multiple bakings.
This pressure hull would be fitted inside an
ambient outer hull/frame able to hold its weight + lead ballast. This
makes it super strong and sturdy, as well you're not attaching anything
directly to the pressure hull later on in life. Areas of acrylic
could be used to transfer EM through the hull, as well as a solid slab of
steel in one section of the pressure hull void of CF. Otherwise your
standard electrical through-hulls would be pre-installed.
BTW, if you're wondering why I'm referring to
1/2" steel, it's because the boat I'm drawing up is 9 feet x 45+ (havent
decided length yet).
All this is fascinating to me... 'course,
anything can be done if u throw enough money at it. :)
----- Original Message -----
Sent: Monday, November 07, 2005 6:12
PM
Subject: Re: [PSUBS-MAILIST] Composite
Hull Calculations
It looks like a lot of the research and analysis software out
there is aimed at wrapping a metal pressure
vessel with carbon fiber, or other filament materials. I think
the fibers are mostly in tension in this application and it just seems to me
a little easier problem than wrapping a steel shell for compression.
It might be a unique use or situation: even a scuba tank will always have a
greater internal pressure than ambient so I'm having trouble thinking of an
application other than a 1atm diving vessels where you'd see a higher
external pressure applied to a shell. ?? And the added buoyancy
would be a negative...
I found some mention of this software, but
couldn't actually find much description or anywhere to download or purchase
it. It sounds fairly good but is for filament winding and for
pressure vessels. And I'd say too that any through-hulls will greatly
increase the engineering over a simple pressure bottle with one
fitting/valve.
NASA code
CF-72124 computer program for the
analysis
of filament wound reinforced metal shell
pressure vessels
On 11/7/05, Shawn
H. <gambit7@bellsouth.net
> wrote:
Yah, I was thinking about the autoclave
process. What about a huge vacuum bag?? Would that be
sufficient? (I have a feeling you're gonna say no)
Ideally, a 1/2" steel tank would be great... but really hard to find
pre-fab from what I can see (in the size I'm looking for).
Doing the hull in sections small enough to bake and/or place under vacuum
is another idea, but then you have to worry about joining.
Argh! Now I see how this can get obsessive.
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