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Re: Real Space Combat Help:

From: "Phillip E. Pournelle" <pepourne@n...>
Date: Wed, 9 Apr 1997 15:22:42 -0400
Subject: Re: Real Space Combat Help:

At 01:06 AM 4/9/97 -0500, Mark S. asked about details to make a SF story
about space combat realistic.

	The first question obviously has to be about the tech level of
the
races in question.  The most basic of these has to be regarding power
plants.
  If you're not able to operate a fusion power plant, you are not going
to
have anything near what we see on B5 or even Space:A&B.  The real killer
is
the mass to energy ratio of not just your ship but the fuel you use.
Remember M(V^2)=M(V^2) is an inescapable physical law (unless you have
reactionless drives).  Even if you use ION engines you have to get the
power
from somewhere and you are spitting mass out to move the rest of the
ship's
mass.  If we assume fusion energy and its not extremely efficient then
you
have relatively large clouds of hydrogen that are super heated by what
little fused into Helium, being exhausted out the back to create your
thrust.  Therefore, you don't have unlimited fuel, and the guy with the
most
fueld (or better fuel efficiency) is going to win the maneuver battle.
	If you can sustain at least 1G of acceleration, you can get out
to
the edge of the solar system in less than a week.  The critical issue is
sustained.
	The next issue is armor/shielding.  Force fields (Langston, Star
Trek, etc.) are fun but not within the physical laws we know of yet. 
The
only ones we really can do are magnetic fields that stop charged
particles
from stars and accelerators.  The real problem are those Neutrons
running
around.  The only thing that stops them is a minimum density of
material.
Water vapor and air protect our planet, and while Lead etc is more dense
it
still requires the same amount of Mass to stop them.  So you will never
escape the mass issue...no matter its material form.
	The High Frontiers Foundation was examining the best kinds of
armour
to use.  You need a heat sink (Mass again) to try to spread you enemies
heating weapons (lasers etc.) out and then use radiant heat exchangers
to
remove that heat.  You also need something to stop those kinetic kill
weapons.  It turns out that infantry have known all this for years, they
call it sandbags, High Frontiers calls it Shaving Cream and Concrete. 
By
placing sandbags around concrete bunkers you prevent shaped charges from
detonating properly, and high enegry kinetic weapons lose energy as they
burrow through the sand (like shooting into water).  On cars today they
do
this with honey-combed plastics backed by steel cages.	The honey combs
collapse absorbing energy and the steel cage protects the passengers.
Therefore hardened space stations would use the same methods.  The
result is
having enough mass to absorb all forms of energy (KE, Gamma, Coherent
light
etc.) and get those radiators working.

>	1.  Which would be better suited for space combat: lasers or
particle
>beam weapons?
	The real issue here would be if Particle Accelerators can be
turreted.  Lasers can operate with axial mirrors.  I don't know if
partical
accelerators can.  If your PA is in the Bow but you need to slow your
closure with an enemy (assuming the engines are in the rear), then your
main
battery is not ready.  Lasers lose coherency after a certain range based
on
the size of their focusing mirror/lens.
>	2.  How does a directed energy beam weapon damage a target?
	For a laser, build up enough heat to cause the armor to
vaporize.
If enough is pumped then you might get a burn through, or better yet, it
will spall on the inside, killing the crew.  From what I've read, Gamma
Weapons can actually impell momentum on a target, if the jolt is strong
enough you can kill the crew, but I think the warhead/reactor on this
one
has to be big.
	For now we would be happy if the laser has enough energy to
blind
all of the sensors and turn the antennas into slag, tus neutralizing a
sattelite.
>	3.  Which sort of missile warhead would be better suited for
space
>combat?  Nuke or kinetic kill?
	A Combination of the two would be effective.  If you have two
missiles of the same mass, then put a nuke in it.  As either weapon gets
closer to the target you want a rapid bloom of material fragments (Nukes
accelerate material pretty well and dense liquified material is just as
bad
if not worse than solid chunks).  If you assume your warhead is salvaged
fused (It goes of when the missile is hit or hits something) then you
get a
bloom close to the target.  The bloom is larger and deployes faster.
	However, a simple KE weapon still has to maneuver close to the
target.  If we assume that the targets close in weapons destroy the two
missiles at the same range then the KE one has a smaller bloom and thus
a
smaller chance of hitting the target.
	The best of both weapons is a nuke that physically hits the
target...  You get all the KE energy (Mass on both is the same) and all
the
NUKE stuff.  Bad day for the target.
	But since the target probably has Close in Weapons, a salvage
fused
Nuke pumped Gamma Laser is best.  Gets as close to the target as
possible,
goes off and directs the nuke explosion towards the target.  Called a
Spurt
Bomb in Footfall.
>	4.  I've heard that it would be a good idea to depressurize a
warship
>before going into combat (the crew would be in space suits).  Why would
>that help?
	Fires on ships at sea are bad, even worse on space ships I'm
sure.
Plus atmosphere is another medium for bad things such as shock and heat
to
travel on and kill your crew...
>	5.  How would one target a enemy ship in space (realistically
that is)?
	Other postings have dealt with this better.  One possibility is
based on what kind of power plant your foe is using.  You could track
the
Neutrino emmision of a fusion plant.  This would give a passive bearing,
there are some things you can do to maniplulate that data but, I've used
way
too much room already.
	For Weapons selection there are a number of issues to consider:
	Lasers are best at Medium range in that they spread at long
range
(lose coherency) but are very high speed (I.E. C).  Hitting you target
and
getting Battle Damage Assessment is fast.  I need to hear from a real
Physicist about the spreading of a Particle Accelerator beam at range...
	Missiles are best at long range.  They travel, are self seeking
if
you put the brains in them, they can deliver a serious punch.  Fighters
have
the same advantage plus they can be recalled and re-used.
	Rail guns, Auto cannons, etc. are best at close range.	You'll
need
to "lead" the target and predict where he will be, etc.  On the other
hand
they make excellent counters to the Missiles and fighters.  They have a
serious mass problem though.  You are expelling a lot of mass that you
spent
all that energy to bring with you...
	All of this assumes that you have a fusion power plant (or
greater)
to run these weapons with.  Otherwise at best you will have a chemical
laser
with limited shots, some missiles, and an assortment of Close in Weapons
on
a vessel that has a maximum acceleration of .5G and a limited fuel
capacity.
For that Play LNL.
  Phil P.

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