Catie Helm made some good comments about starship hulls, and
I'd like to keep going along those lines.
One thing that should be noted first is that the analogy between
submarine hulls and starship hulls is not exact; at least in traveller,
they have different engineering goals, though similar. A submarine has
the goal of resisting incredibly high pressures from the outside, and
all else (including hull shape, materials, design of hull penetrations,
etc) is organized around that engineering requirement. Starships in
Traveller, on the other hand, have relatively puny hull stresses from
atmospheric pressure inside. The space shuttle's cabin is made of
very thin aluminum sheet; resisting 15 psi is easy. Re-entry imposes
higher stresses (much of it thermal), but in Traveller you can
easily pick your reentry speed, so those are minimized. The closest
TML has come to determining why starship hulls in Traveller are
so heavy is that they have to block radiation, and the hull mass
that's described as "standard" hull, w/o additional armour, is just
about the right amount to limit lifetime exposures for starship
crews (accumulated flare radiation and Galactic Cosmic Radiation
exposures) to levels with minimal health effects.
Hull Armour for armour's sake is different; there, it's the
local thickness and toughness that matter. The hardest part of armouring
starships is again, as in submarines, designing tough penetration points.
However, you have the advantage that the stresses you're working
against are potential and transient (impact, laser, etc) as opposed
to constant (submersible pressure). It's reasonable, from a design
point of view, to trade off absolute armour protection in a small
area, if you've got a reasonable probabalistic chance that it won't
be damaged. You can't do that with sumbarine hulls 8-)
Enough about hull design issues. Now, on to superdense...
I've been thinking a lot about Superdense armour too, and here's what
I came up with.
Making hull plating thinner is not a good idea, for one reason:
thin plating is not stiff. However, we've got these nifty high-strength
dense matter materials. How _do_ we use them to best effect in spacecraft?
Well, we use them the same way you use high-strength materials in
aircraft now; you make composites.
Imagine a composite material made of say Aluminum metal and
thin (0.1 mm) fibers of superdense material woven into matting which the
aluminum was cast around (or whatever). Since the matrix material is
Aluminum, you can weld it, cast it, or do whatever else you want with
it. If you heat it a bit, sheets of it can be formed and bent.
However, the strength and toughness and impact resistance
are primarily in the superdense fibers, as in present-day composites.
Advantages? The average density is lower than pure superdense,
so the stiffness is increased. It's working characteristics are better
since you can weld it and form it relatively easier. And the variable
density/hardness characteristics resist penetration better than
homogenous materials.
- -george william herbert
[email removed]