Catie sez:
}I do however, know a great deal about submarines
}The way I see it, the problems with builing a hull for a submaine
}& a hull for a traveller space craft can't be too different.
Ah, one point about starship hulls vs. sub hulls: A sub must
take a LOT more pressure than a ship (normally). The pressure is
also in the opposite direction. A starship will usually have an
interior pressure of say 6 psi. (I believe that's the pressure in
the NASA Space Shuttle). The pressure on a sub hull doubles every
time the sub drops a few feet or so.
(Sorry for the English units...)
George Herbert's (the naval architect) estimate was that an armor
40 hull could dive to 495 meters purely on the hull strength.
Seems to me that that depth could be augmented by increasing
interior pressure. After all, with all the gas handling equipment
in the environmental control and the liquid hydrogen fuel, it
should be a simple matter to raise interior pressure.
}The problem, he said, was that you had to make holes in the hull,
}for the drive shaft, for the hatches, for the cooling water
}intakes. It's the holes that are the "weakness" in withstanding
}the great pressure gradients.
}I opine that it's advances in making one-piece hulls of
}suitable thickness that's the trick. If you could weld a hull of
}titanium or steel, or better yet, if you grow a single crystal of
}metal into a formed hull, then that's what required.
}Early submarines were rivetted together!
}(remember the great scene in Das Boot where they had to dive to
}bottem near Gilbratar, & the rivets starting popping in the hull?)
Great movie... fave scene... But making a one piece hull with
stuff like crystal iron is gonna be virtually impossible. I read
a while back that they are just starting to make crystal iron
turbine blades for jet engines. A very difficult process: The
metal is poured into a mold. To get the metal to crystalize
properly, they have a helical offshoot of the mold to get a seed
crystal in the proper orientation. ie. inside the helix, crystals
grow with random orientation. When allowed to cool properly, the
base of the helix will form a seed crystal with the proper
orientation to the turbine blade. Now this works real nice for
thin turbine blades, as the blades are kinda crystalline in form
anyway, but imagine getting a starship crystalline shaped. :-P
A one piece crystal hull will be very hard to repair.
Ceramic materials are gonna be rough too. Why does the US M-1
Abrams Main Battle Tank look so boxy? Ceramic armor. (Those are
obviously not one piece hulls)
Composite Laminate ought to be easier to shape, but it is very
difficult to work with. Patching & repair will be ROUGH.
Titanium: The Soviets (Russians?) put a BUNDLE into titanium
working. But the Alfa subs are the deepest diving attack subs
around. Read Kelly Johnson's autobiography "Kelly: More than my
share of it" p141 (EXCELLENT book) about the problems of building
the titanium SR-71.
Parts would shatter, titanium pieces would get 'poisoned' when
coming in contact with cadmium tools, and break off, tool bits
would refuse to cut titanium... The Russians (?) are the only ones
who have a large enough titanium press to build subs hulls. If
Lockheed's skunkworks had such an awful time, there's no telling
how much difficulty the builders of the Alfas had.
One of Metlay's ideas I really liked (his story in the Horde :-)
was the idea that under some kind of field, superdense armor became
fluid and was workable. Thus you could make a single piece hull
MUCH easier than you could with any of the other materials
previously mentioned.
}The hull
}perforation problem can be taken care of by arm-waving good enough
}iris hatches.
An iris hatch is still a hole in the hull. Problem not solved.
}What does super dense really get us anyway? Perhaps better armour
}for naval & scout ships. But why invent a new material when what
}we have is sufficient (in my opinion)? Not only that, but
}consider that those super-dense material are going to be a bitch
}to weld - & that's the big problem in my mind anyway!
Horde excerpt: written by Metlay
"But the real boon, and the discovery that got the corporate gears
turning, was the development of the RAMKS by Provost and Mills in
601. Up until that time, the welding and fitting of superdense
hulls was considered an expensive luxury, due to the difficulties
in getting the impenetrable materials to bond together easily. The
RAMKS (an acronym for Robo-animechaniakatasthyser) was a
man-portable device incorporating fusion and grav technology to
induce superfluid states in confined areas of superdense hullmetal,
allowing smooth joins as easily as two copper pipes could be
soldered together with a brazing torch."
Ok, maybe it is a bunch of handwaving, but so is a lotta trav tech,
and this sounds damn cool.
How's that sound?
2G Scott
PS. 2T Matt:
Yeah, sputtering a hull COULD work, but it would take forever
to get a hull 33mm thick when you are working on depositing
MONOlayers of atoms. But if you had forever to wait, you could
grow a single crystal hull that way. Hmmm... A DIAMOND yacht? :-)
But if crystal growing technology was that good, then there would
be no value to natural crystals. Something that Trav doesn't have.