From: pksuk@mothra.syr.EDU (Peter K. Suk)
Subject: Re: Weapons systems?
Keywords: high-G space weapons
Organization: Syracuse University, Syracuse, NY
Date: Tue, 17 Nov 92 00:58:34 EST

----- In article <u894793.721933895@bruny> (T. Little) writes:
>pksuk@mothra.syr.EDU (Peter K. Suk) writes:
>>Of course, the more efficient your drive is, the less mass you have to
>>carry around, and the more it seems like a reactionless drive.  One the
>>most efficient drives would be a mass-driver or railgun capable of
>>hurling specks of stuff at relativistic speeds.
>
>If you have significant quantities of antimatter, you could use the photons
>produced by annihilation for thrust.  You *can't* get any better delta-V
>from such a rocket (by known physics)...

True, we're all pretty solidly limited by c and E=mc^2.  I was wondering
if there were any _tighter_ upper bounds.  If you stipulate that your
warship's drive systems be made from solid state matter, then you start
to get some interesting dynamics.  

A limit on the energy gradient of an accelerator interests me because
it would bound the capability of ships of a given size.  We could say
that a ship of length L would have thus and such max delta-V / mass
efficiency.  For one thing, this would necessitate different roles
for craft of different sizes.  If we make other assumptions about
materials technology: for example -- that we will never make something
with more tensile strength than a molecular bond -- then we get another
limit on the rate of turn for craft of length L.  

From that, we can get relationships for offensive capability versus
manuverability versus range. A ship that capable of a certain acceleration 
has a certain safe distance from which it cannot be hit _at all_, due to
the fact that information doesn't propagate faster than light.  Given
enough distance and accelerating ability, the ship can make sure that
you will never know where it is precisely enough to hit.  

If we place speed limits on our weapons much lower than light, then
interesting interactions take place.  Minimum safe distances and the 
accelerations required to effect them start to get down to levels where
they can play a role in space combat.  If the weapon's speed limit is
related once again to the size of your craft, then you get even more
differentiation between craft of different sizes.  (Calculations
forthcoming.)

(If you haven't guessed, all of these assumptions justify 'fighters' and
'carriers' and huge 'dreadnoughts.'  I guess I never built enough of those
plastic models as a kid.)

Right now, I'm stuck.  I can get limits for electric field gradients.
(From _Sci Am_, Amateur Scientist, Apr 1989: 10ev per 10E-8 cm.  A 
hilarious article, if you haven't read it.)  However, B-fields look
to be harder.  You can make the B-field in a solenoid arbitrarily 
strong by adding more turns / length.  But eventually your wires get
so thin that your current has to drop off.  (Remember we're dealing
with solid state matter.)  So there seems to be a limit in there
somewhere.  Can any one lend a hand?

	--Peter Kwangjun Suk

[P.S.  ----- T. Little writes:
>For a photon-drive, you have an effective exhaust velocity of 'c'.  You can't
>use the Newtonian approximation for momentum anymore, though.

Until your _craft_ becomes relativistic, momentum is momentum is
momentum.  (And even when it does, it still might be -- I don't
know.)  The photons hitting the vanes of a radiometer are
'relativistic' but the thing will behave the same way in a light
breeze (discounting air resistance, of course.)		]

[P.P.S.  No offense meant, Tim.  I just like bantering with you.]
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