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Aha, I think I
understand. I'm sure there's a technical term that escapes me, but if I'm
correct what you're visualizing is similar to the sort of lattice
structure you might see in the construction of a bridge or crane, except built
around an enclosure. The water inside this exostructure would
not contribute any strength, but you would want it there just to avoid air
filled voids subject to compression. Have I got it?
I do think it could
"work" in the sense of being stronger than the unreinforced cabin. BUT I would
really question why it would be cheaper that a cylinder. A cylinder is
inherently much more efficient, it will use both less material and require
less fabrication. And most importantly a cylinder doesn't have all the stress
concentrations found in a structure built of triangles. If by "afford"
you were referring to space instead of money, you can always stiffen a cylinder
by putting the rings on the outside. To put it in the simplest terms, flat
surfaces or sharp discontinuities should be avoided like the plague when
designing a pressure vessel -- no exceptions. If all this were for an ambient,
then of course you could do anything at all with the shape of the
hull.
And
now, as Monty Python say, for something completely different...
Put on
the comic book or sci fi writer hat. Make the double hulled sub, but FREEZE the water between
the hulls. Throw away both the inner and outer hulls, otherwise known as molds.
Now dress as a commando, approach an enemy shore on a suicide mission, and
conceal your sub after landing by letting it melt. Or carry it with you and
drink it. Hey, you wouldn't even need viewports.
:)
Alec
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Recon1st@aol.com Sent: Wednesday, October 18, 2006 1:37 PM To: personal_submersibles@psubs.org Subject: Re: [PSUBS-MAILIST] call it a double hydro hull In a message dated 10/17/2006 10:16:28 PM Central Daylight Time,
Alec.Smyth@compuware.com writes:
I'm afraid that idea is one that is proposed quite regularly but doesn't hold water Alec I am aware of what you are saying and understand it.
The reason I was thinking on doing it is not to strengthen the inner
hull
walls but the skeletal.
I am thinking on a basic 2ft skeleton the length of the sub. Steel triangle
shaped
hull plates will be welded to this skeleton. The outer skeleton and walls
would only
add strength to the skeleton. I can not afford to go to a cylinder type
hull so have
opted to build oh say at least a 12 sided faceted hull. which means many
triangle
shaped hull pieces. And yup I am talking about much much welding. I do have
a
friend that can CNC plasma cut my triangles so accuracy should be able to
be
achieved. The outer skin will basically just stream line the beast for more
speed
and agility.
But I do think it might be more work then it is worth. still thinking
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