Re: Real Space Combat Help:

In message <9704091126.AA30373@zeorymer.alf.dec.com> you wrote:

> >	I'm writing a sci-fi space combat story for my creative writing
class. 
> > So far I've got most of the story fleshed out.  However, I want to
be as
> > plausable and scientific as possible. (The only place where I want
to be
> > technically vauge is hyperdrive.)  I have some general questions for
all
> > of you armchair physicists out there in GZG Mailing List land.
> 
> Before we get into these questions, let me heartily endorse the
> tactical manual that accompanies Renegade Legion: Prefect.  EXCELLENT
> discussion of the strategies and considerations of high-speed
> high-thrust space combat and gives plausible and sound
> tacticat/strategic considerations of the solar system as a war
> theatre.

Sounds good, but I don't like Renegade Legion itself too much,
and getting hold of it is a real pig anyway.

> >	1.  Which would be better suited for space combat: lasers or
particle
> > beam weapons?

There's also drive systems to take into account - ask any Kzin :)
(a reaction drive puts out lots of energy, over a reasonable
range, so even an 'unarmed' freighter has at least one weapon).

> >	3.  Which sort of missile warhead would be better suited for
space
> > combat?  Nuke or kinetic kill?

Another type of missile is a nuke which is used to power a (one shot)
gamma ray (or other high frequency) laser. A good example of this
sort of combat is at the end of Footfall, by Niven and Pournelle.
Lots of use of burst lasers.

The big problem in space is delta-vee - or rather the lack of it.
This is a measure of how much velocity change a vehicle can perform
before running out of propellant. For missiles, you generally want
to close with the target as quickly as possible - which means
burning lots of thrust early on. Which leaves almost nothing for
the close-in manouevering needed at the end of the flight to get
a direct hit.

For kinetic kill, you probably want railguns rather than missiles,
they're a *lot* cheaper giving that success ratio is going to be
extremely low in either case. If you've got a guided missile,
it's probably best putting a nuke on it.

> through them.  Kinetic kill missiles are a lot better for close in
> dog-fighting between fighters and mass waves thrown at cap ships as
> they close.

I have my doubts about the use of fighters in realistic space
combat, but then I'm part of the 'big ships are better' crowed,
and fighters are just a very small ship.

What may be useful are drones - unmanned fighters carrying limited
duration weapons (a few missiles, or limited power for direct
energy weapons). For a small fighter, too much of ship mass is
wasted on life support for the pilot. At close range, they're
fragile enough that survivability probably won't be acceptable
for a manned weapon system.

>  Missiles will /always/ win out, in the end, over directed
> energy weapons, I feel, because of their inherent range benefit and
> the self-directing nature of the beast, quite possibly light-seconds
> distant from both firer and target.

Very true, but lasers make for good point defence against missiles.

Something else that should be said, is that any ship with a
limited delta-vee can't keep on dodging for ever. It's often
claimed fact is that you can't hit a target at light-second
distances, because it can dodge in time. But since the ship
doesn't know 'when' it's going to be fired at, it has to dodge
all the time, which is going to burn propellant way too quickly.

I tend to see ships as going for heavy armour rather than
manoevrability, with lots of direct energy weapons. At any
decent range the lasers won't do much damage (laser intensity
falls off with the square of the distance), but it persuades
the enemy to keep away from you enough so that they can't
use their direct energy weapons. Greater range also means
longer flight time for missiles, giving you a better chance
of detecting, tracking and destroying them before they get
you. Regardless of armour, a single nuke can really ruin your
day.

> Then, of course, there's the truly massive `spinal mount' Gauss
> accelerated crowbar, but I don't think its a realistic weapon to use
> against other cap ships unless they're nearly dead in the water.
> They're mother-evil against ground-based targets, though.

If the enemy controls orbit, then don't *ever* fight an open ground
battle, unless you're absolutely positive all enemy weapon platforms
will be over the horizon.

> >	5.  How would one target a enemy ship in space (realistically
that is)?
> 
> Very carefully.  Depends on your technology level.  At the very
> highest, you use gravitic warping detectors to locate areas of mass
> that are moving incident to you.  At lower levels, you'd probably use
> a combination of radiation detection (most visible when the drives are
> running) and checking out who's firing at you.

A ship with a human crew will have at least part of the ship at
around 300K, against a background of about 4K. That's ignoring
heat from reactors, drives (they don't cool to background temperature
as soon as they're switched off) etc.

> A ship painted black, that accelerated way out in the area outside
> your solar system, with most everything powered low, could fall down
> the gravity well of your sun, right by your listening posts and you'd
> probably never see them.

The problem with this is, either you're willing to wait months or
years to get to the target, or you have to start your 'fall' at
extremely high velocity - which means flashing past the target
at several thousand kps.

This isn't as bad as it seems though, because you just launch a
big volley of missiles before you close, which will hopefully
close to within killing range of the enemy before they can react
(or even detect them). In a matter of seconds, you could destroy
the enemy fleet.

You then spend the next six months decelerating, and coming back
to the target world to actually capture it :)

>  Putting off no radiation.

That would be putting off relatively little radiation.

> They could be just a big rock, for all you know.

If attack a world, this is of course what you'd use. A world can't
dodge, and follows a totaly predictable orbit. Launching the rock
two years ago isn't implausible.

>  If they released a flight of
> fighters that are coasting into your system on a different trajectory
> to do a recon of some of your sites, the only way you'll see them is
> when they do some course correction on their high-speed fly-by.  You
> may or may not have some interception forces that can get into their
> maneuver sphere and envelop theirs with yours.  If not, they'll likely

As soon as they make a burn though, you know where they are, and
where they're going. Even if they go dark, and are undetectable,
you still have a very good idea where they are over the next few
seconds, minutes, hours or even days or weeks (depending on how
good your computers are).

On top of that, they *will* be detectable. If you know where to
look, it is very easy to detect something in space. If the enemy
isn't expecting you, creeping up on them undetected may well be
an option.

> burn like mo'fos and rendezvous with their dark carrier once they
> outmaneuver you.

Good. The enemy wants you to do this, because you've just told him
where the carrier is. One dead carrier. Want you want to use are
disposable weapon drones which you leave to die. The carrier only
reveals itself if the battle is won. If not, it follows its
trajectory out away into space.

> >	6.  There would happen to be a "Theoretical Space Combat FAQ"
somewhere
> > on the net?  If there isn't there should be.
> 
> The tactical guide with Prefect is about the only one I've ever seen,
> and it includes cool little diagrams, etc.  :)

The "Aliens Technical Manual" has some good discusion on space
combat (somewhat strange, since space combat never occurs in
any of the films...). It brings up the good point that battles
will generally be fought around planets. There's no point
defending empty space, since it's not useful, so it makes more
sense to concentrate your forces at some strategic points.

Also, try rec.arts.sf.science - this subject crops up quite
often there, and there's lots of physicists etc who know
what they're talking about (excellent source of info for
power outputs of lasers, delta-vees of engines etc).

> 
> Geez, this turned into a regular dissertation ...
> 
> 
> 

-- 
Be seeing you,
Sam.