"Realistic" Spaceship Combat
John P. Raynor
combat between spaceships might look like? By "realistic" I mean:
<A> respecting the laws of physics as they are currently understood
<B> depending solely upon technologies which already exist, or which can
be clearly extrapolated from existing technologies (fusion reactors,
for instance, would be acceptable, but force fields and reactionless
drives would not).
Any suggestions, including material which has nothing to do with gaming,
would be gratefully accepted.
- J. Raynor
Jim Walters
: Can anyone suggest good sources of information regarding what "realistic"
It depends on the technology you will be using. Are you going to be using
fairly advanced technologies like Bussard ramjet type spacecraft? (It's a
relatively fast STL ship which collects interstellar hydrogen with a
magnetic field, and then burns it in a fusion reactor. We are at least a
century away from actually building one, but I think it is theoretically
possible.) If you are, you might want to look at the Larry Niven novel
"Protector". About 3/4 of the way through the story there are some
simulations of battles between Bussard ramjets, and then an actual battle.
There are some interesting tactics that he mentions, although they are
rather specific to the ramjets.
If you are looking at technologies closer to what we have today, then you
are more or less limited to guided missles for longer ranges, with
railguns and directed energy weapons possible for shorter ranges.
In either case, you will need to find some source on celestial mechanics.
Some of the effects are non-intuitive. For example, if you are orbiting a
planet and speed up, it will take you longer to get to the other side of
the planet than if you stayed the same speed you are now. Unfortunately,
all the sources on celestial mechanics I can think of are fairly
technical. Does anybody know of a popular treatment of the subject?
If you go for the high tech option, you might also need a basic reference
on special relativity. Fortunately, there are scads of non-technical
books available.
--
Jim Walters jwal...@clark.net
"My race is pacifist and does not believe in war.
We kill only out of personal spite." Brain Guy - MST3K
Tim
: Can anyone suggest good sources of information regarding what "realistic"
: combat between spaceships might look like? By "realistic" I mean:
I'd say they'd be fairly sterile and passionless. Assuming large radius
weapons, good targetting and decent propulsion systems, the PCs would be
out of the loop, and assuming decent battle computers, so would the
players.
From a role-playing point of view, the PCs would be informed that their
ship was damaged, and / or the opposing ships were damaged and retreated,
or destroyed. No dogfighting.
Think the bland passages recounting starship combat in "The Forever War".
tim
John Rudd (yes, that's really my email address)
> <B> depending solely upon technologies which already exist, or which can
> be clearly extrapolated from existing technologies (fusion reactors,
> for instance, would be acceptable, but force fields and reactionless
> drives would not).
Actually, a reactionless drive may be closer to reality than you'd think.
Here's URL for information on a some experiments that have been going on
with respect to Woodward/Mach's principle:
http://www.inetarena.com/~noetic/pls/woodward.html
--
John "kzin" Rudd kz...@domain.org http://www.domain.org/users/kzin
Truth decays into beauty, while beauty soon becomes merely charm. Charm
ends up as strangeness, and even that doesn't last. (Physics of Quarks)
-----===== Kein Mitleid Fu:r MicroSoft (www.kmfms.com) ======-----
John Rudd (yes, that's really my email address)
>
> I don't know what system, if any, I would use as a
> starting point. It's something I would be interested to look
> into.
The old Ringworld RPG had a lot of interesting stuff in "The Ringworld RPG
Companion" book. Things like acceleration charts showing relative movement
distances, over time, at various G's of thrust, etc.
If only Chaosium would put it back in print :-}
(No, I wont sell my copy)
bdy...@network.boxmail.com
Space battles in the comic book Albedo are like this. Ships spend a lot
of time lining up for an approach at each other, they release a swarm of
self-controlled combat vehicles, and plow through each other's clouds.
The classican boredom and terror version of combat. I'm not sure how
shaceship combat is handled in the RPG, but I imagine it's essentially
rolling dice to see how many weapons get through and what damage they do.
The ships have ion drives of some kind, fusion power, and no artificial
gravity tech, so it's not too unrealistic.
From an roleplaying point of view, combine a slow sub battle with jousting
or a game of chicken.
--
Brian Dysart | The RNG giveth, and the RNG taketh away.
bdy...@network.boxmail.com | "...and eight for the fruit bat."
www.rahul.net/bdysart/ | <*> Code Code block: C---
John Kim
John P. Raynor <jra...@pantheon.yale.edu> wrote:
>Can anyone suggest good sources of information regarding what
>"realistic" combat between spaceships might look like? By
>"realistic" I mean:
>
>
> can be clearly extrapolated from existing technologies (fusion
> reactors, for instance, would be acceptable, but force fields
> and reactionless drives would not).
>
>gaming, would be gratefully accepted.
Well, I had a discussion about this some time ago. Here
is a summary of some of the ideas I had:
-------------------------------------------------------------------
This is an outline of what a "realistic" space combat system
might be like. This assumes a fairly high level of technology
(i.e. enough that interplanetary flight is routine, say) and ships
and hardware which are designed for combat.
I assume that missles and unmanned drones can consistently
generate 10g or more acceleration. Manned ships are of course
limited to 5g or less. Actually interplanetary or interstellar
craft will be very large and dominated by fuel tanks. Smaller
military vessels with comparatively short range would be the
front line of fighting.
A major point, noted in _Traveller 2300_, is that combat
is very long-ranged, and an important part of the problem is
*finding* the enemy. A couple of general comments here:
1) Combat ships are liable to have a stable of decoys (which simulate
the ship's IR and radar profile) and drones (remote sensor
and weapons platforms). Manned fighters are unlikely since
humans can't survive massive G-force accelerations.
2) Weapons targetting and sensing is done by computers: i.e. your
"to-hit" chance shouldn't be a simple skill roll, since it is
not a question of lining the enemy up in your gunsights.
3) If opponent's are approaching each other, "combat" is slow as
they face off at massive distances (i.e. 100,000 kilometers)
just after detecting enemy presence. At this point, it is a
fairly slow chess match of distinguishing the enemy from his
drones and decoys.
4) The drones will engage with missles, lasers, and perhaps particle
beams. The beam weapons will primarily be defensive (i.e. anti-
missle defense), for revealing decoys, or for setting up a target
for destruction by missles.
5) Anti-missle defense might be good enough that heavy ship-mounted
beam weapons or rail-gun missle launchers are critical to taking
out the enemy. In this case, though, everything should generally
resolve after just one "pass".
6) If combat does unexpectedly erupt at short range (i.e. say if
face-to-face negotiations go awry), then the results will be
swift and terrible.
The question of using nuclear weapons is important. However,
even if strictly nuclear weapons are disallowed, one can come close
to a tactical nuclear strike with advanced chemical missles.
-*-*-*-*-*-*-
As for how to run such a thing. I would probably have a
2-dimensional map (simplification, of course, but probably a
neccessary one) where I lay out the "blips" that appear on the
PC's sensors and they lay out their drones and/or decoy(s).
They have some time at this point to choose an approach,
negotiate with the enemy, etc. Note that communication can be
achieved without revealing your position if you relay through a
remote drone using laser communication, say.
You need to give players some benchmarks in Newtonian
acceleration, and play aids which relate acceleration (in g's)
to distance and time. You probably want to use some generic
unit like "klicks" where a "klick" is 1000 km or 10,000 km.
Weapons obviously need ratings in range and damage.
-*-*-*-*-*-*-
John Kim
Jim Walters <jwal...@shell.clark.net> wrote:
>It depends on the technology you will be using. Are you going to be
>using fairly advanced technologies like Bussard ramjet type spacecraft?
>(It's a relatively fast STL ship which collects interstellar hydrogen
>with a magnetic field, and then burns it in a fusion reactor. We are
>at least a century away from actually building one, but I think it is
>theoretically possible.)
Actually, I think this one has already been ruled out. Given
the scarcity of interstellar hydrogen, I believe it can be shown that
the amount of energy is takes to collect the hydrogen is *less* than the
energy that could possibly be gained by fusing it.
I haven't done the calculation, myself, although I suppose I
could. The mean interstellar abundance of hydrogen is about
0.05 protons per cm^-3. The energy gained by fusing protons
is at most about 5 MeV per nucleon, I think. Now the hydrogen
has to be collected before the ship passes (although for a slow
ship the energy limit will be from the hydrogen temperature, which
I can't find right now).
It's actually been suggested that the ramjet might be extremely
useful for interstellar travel as a *brake*, so that the spaceship
doesn't need to bring reaction mass to slow itself down upon reaching
its destination.
Ilkka Mannisto
> The question of using nuclear weapons is important. However,
> even if strictly nuclear weapons are disallowed, one can come close
> to a tactical nuclear strike with advanced chemical missles.
Why would the nukes be disallowed in the first place? Radiation really
isn't a problem in space, because no civilians will suffer from it, and
the ships probably will have some kind of protection against it.
Timothy J. Miller
> Why would the nukes be disallowed in the first place? Radiation really
> isn't a problem in space, because no civilians will suffer from it, and
> the ships probably will have some kind of protection against it.
Give the lack of overpressure blast effects, nuclear warheads
would need to be in virtual contact to have any of the destructive
effects we visualize these types of weapons as having. You'd be
better served by discarding the warhead, using the capacity for
reaction mass, and going for a kinetic energy kill.
Nuclear weapons might prove useful if enhanced to produce more
ionizing radiation, which would play havoc with the target's
electronics. Of course, we're reasonably close to optically-based
computers, which would effectively negate that type of attack.
You might suppose that the radiation effects be used to kill
the crew; but the lag time between detonation and when the exposed
crew becomes too sick to remain in fighting shape is long enough that
they might kill *you* first.
In short, you don't need to disallow them; in space combat
they're just not all that useful.
William Clifford
Raynor) wrote:
>Can anyone suggest good sources of information regarding what "realistic"
>combat between spaceships might look like? By "realistic" I mean:
>
><A> respecting the laws of physics as they are currently understood
>
><B> depending solely upon technologies which already exist, or which can
> be clearly extrapolated from existing technologies (fusion reactors,
> for instance, would be acceptable, but force fields and reactionless
> drives would not).
>
>Any suggestions, including material which has nothing to do with gaming,
>would be gratefully accepted.
This has come up in rec.arts.sf.science a lot to the point where a lot
of the regulars are sick of talking about it. Do a search in deja.com
for the relevant discussions. There are a lot of problems for someone
who wants to pursue a policy of aggression in space but they are
interesting ones. I've put some of the posts from those discussions on
my webpage at <www.ionline.com/wobh/paq/paqtoc>.
The chief of which is that your ability to see and know intimate
details about the enemy is much greater than the practical weapons
range. You can't hide. Space ships are delicate but hot glowing
things. They'll show up in infared a long way off.
You can't well disguise yourself either. An effective decoy will have
but putting out as much energy as real ship in all kinds of
wavelengths that it might as well just be a real ship.
Space opera force fields are basically unphysical so the best defense
is just to not get hit.
Observation, anticipation, and preparation, are the principle
strategies. Because you can see what the enemy is up to pretty much at
all times you might as well keep a close eye on him.
Actual effective weapons range is something like 100,000 km. You can
hit them from further than that of course but they can see you trying
and can prepare appropriately. Because of this I imagine fleets of
kamikazi drones rather than human occupied warships.
Space is big. Mars won't be going to war against Earth anytime soon
and not at all with current technology or anything I can see being
extrapolated with current tech.
Space tech is expensive. With all the money and work required to get
up there a space fareing societies most vulnerable spot is economic
not physical. Economic warefare is quite as brutal as a military
campaign in my opinion. I don't know how your players will feel about
playing monopoly in space but I personally think it would be pretty
fun. Economic, technological, and resource self-sufficiency for space
stations would be the first requirement for a hot war in space that
will not rely on material support from Earth for it's trump card. I
suspect that this is a long way off.
--
|William Clifford |"Baggins? We don't need no steeking |
|wo...@yahoo.com | Baggins." |
|lame webpage at: | --Thorin Oakenshield |
|http://www.ionline.com/wobh | _Treasure Under the Lonely Mountain_ |
John Rudd
>
> I don't know what system, if any, I would use as a
> starting point. It's something I would be interested to look
> into.
I had another idea for a way to model a semi-realistic hard-sf space
combat system.
It's somewhat abstract, though (but still involves some degree of player
decision making and stuff). It's based on the "Fencing" rules from
Castle Falkenstein.
Each ship has a detection/prediction rating ... this may be based upon
the ships computer, a telepath-navigator, a mentat (human computer),
etc. But, essentially, each ship has a rating of how well they detect
and predict the presence and actions of the opponent. Also, this system
only works for 1 on 1 confrontations ... so you either have to only use
this for dueling ships, or when faced with fleets, you have to model
each fleet as 1 conglomerate entity with 1 total rating for each fleet.
Each ship or fleet also has an attack rating (number of missiles it can
launch in a single volley, or whatever) and a defense rating (number of
missiles it can intercept from a single volley, etc).
You have 2 units of time: the turn and the round. Each turn consists of
a series of rounds, depending upon the d/p rating of the ships in the
combat. In a given round, each ship picks 2 actions from 3
possabilities: attack, defend, nothing. Your d/p rating specifies how
many attack and/or defend actions you can take per turn. The turn is
over when both sides have used all of their attack and defend actions.
(note: it is useful to do your best to keep your opponent from knowing
how many attack/defend actions you get).
So, you could have a sequence like this: Lets say ship A has a d/p
rating that
gives it 4 attack/defend actions per turn, and ship B has a d/p rating
that gives it 5 attack/defend actions.
round1: A (attack, defend) B (defend, defend)
round2: A (defend, nothing) B (attack, defend)
round3: A (nothing, nothing) B (defend, nothing) (B is now out of
attack/defend's)
round4: A (attack, nothing) B (nothing, nothing) (B can't do anything
else)
There is no round5, because A and B have both used all of their
attack/defend actions.
Resolving:
If one side makes an attack that is not defended, then the attacker's
attack rating is compared to the defender's defense rating, and damage
is applied. How exactly that works can be filled in for each game.. if
you're only talking about missiles, then you really only have 1 rating:
missile launch rate (and perhaps missile quality), and each round you
will also have to decide (in advance) how much of your rating to use for
your attacks and how much for your defenses. So then you'll compare
them to see how many, if any, missiles get through your counter measures
to do damage.. then you compare the damage potential of the missile(s)
to the hull and armor rating of the taget ship, and apply hull/armor
damage.
You can also add in "defensive only" systems, like sand casters and
rapid fire close range lasers (range refering to tracking systems, as
opposed to beam range) and things like that. These would boost your
defensive rating, but not be available for your attack rating.
If a defense is played, then it automatically is used to counter one
attack if one is played against it (in other words, order doesn't matter
... if A does "defend, attack" and B does "attack, defend", order
doesn't matter, so they both cancel eachother).
Castle Falkenstein actually has some fancy things like a "attack attack
vs attack attack results in locked blades" and "attack attack vs anthing
else results in some special event" kind of rules, but they probably
don't apply as easily to ship to ship combat. Especially not if a
single undefended attack where your attack rating is better than their
defense rating is likely to kill the ship anyway, then it's just a
matter of the GM's descriptive narative :-)
--
John "kzin" Rudd jr...@cygnus.com http://www.cygnus.com/~jrudd
Tim
>The players will actually play the computers. But that doesn't
>mean they have to act like mindless robots or whatever; they actually do
>whatever they want, with all the sneakery and strategy that makes RPG's
>fun
Well, it does give the players a sense of control over their destiny,
but at a distancing that I myself would feel odd regarding. It's like
playing a squad-level tactical game, then having the players randomly
determine if their characters (either singly or collectively) were
in a unit that was destroyed.
For me, I'd rather my rp'ing be done 'first person'. Moreover, I'm
not sure I can accurately represent a battle computer - my tactical
aptitude sucks rocks.
tim
Ross M Stites
>Can anyone suggest good sources of information regarding what "realistic"
>combat between spaceships might look like? By "realistic" I mean:
><A> respecting the laws of physics as they are currently understood
I remember the old Spacemaster (spinoff of Rolemaster) combat rules being
very good here.
><B> depending solely upon technologies which already exist, or which can
> be clearly extrapolated from existing technologies (fusion reactors,
> for instance, would be acceptable, but force fields and reactionless
> drives would not).
I'm not sure about that angle.
Ross
John P. Raynor
The inverse-square law is such a huge disadvantage. I can see using
energy weapons to dazzle, cook, or even vaporize incoming missles
(particularly "smart" missles, which might be able to evade projectiles),
but I think that G.D.W.'s "Traveller" rules hit the nail soundly on the
head when they said that one very effective way to destroy a target is to
deliver a substantial dose of kinetic energy with a bullet. Ordinary
missles and railguns firing hybrid "missle-bullets" (with a limited
ability to make course corrections) both seem pretty attractive.
- J. Raynor
George W. Harris
thusly:
= Actually, I think this one has already been ruled out. Given
=the scarcity of interstellar hydrogen, I believe it can be shown that
=the amount of energy is takes to collect the hydrogen is *less* than the
=energy that could possibly be gained by fusing it.
I think you might have meant 'more'.
--
When Ramanujan was my age, he had been dead for five years. -after Tom Lehrer
George W. Harris For actual email address, replace each 'u' with an 'i'
Eric Stevenson
If you've got enough energy or good enough focusing to get a decent
range, energy weapons have some nice advantages. The beams move at or
near the speed of light, cutting down on dodging time. They are
correspondingly hard to detect before they reach the target. The beam can
only be detected by those in its path, so no one else knows where it came
from. The beams are largely unaffected by gravity.
Another possibility is a slow kill. A high energy particle beam could
deliver enough ionizing radiation to kill over a few hours even without
being able to do much physical damage. This might be effective over very
long distances, since fairly low energy densities are needed to kill
humans. Shielding is pretty heavy, especially for extremely high energy
particles.
Kevin J. Chase
<rach...@ms35.hinet.net> wrote:
>
> I'm trying to develop a semi-realistic SF RPG, and I do include
> ship-to-ship combat in it. I agree that playing out a realistic
> high-speed confrontation would be extremely boring for the PC's, or at
> least for anyone playing a human. However, I'm toying with an idea that
> (if a combat ever comes up in a game) will let the players actually take
> a hand in starship combat.
>
[snip!]
>
> So... The players will actually play the computers. But that doesn't
> mean they have to act like mindless robots or whatever; they actually do
> whatever they want, with all the sneakery and strategy that makes RPG's
> human-like timescale, but rather computer control systems. It might
> just be an excuse, but I think it's a rather good one.
Wow. I _like_ it! In fact, I think I'm stealing it.
The ``sit back and let the machine handle the fight'' vision of space
combat always felt ... well, boring. And most likely to be accurate,
too.
It just didn't seem like combat without the romance of leading your
squadron of battlecruisers into the enemy line ... at least, not
combat worth role-playing. I probably feel the same way a 13th
century knight would about combat today. ``No more cavalry charges?
<*sniff*> What's the _point_ then?'' The romance might still be
gone, but at least there's something for the players to do this way.
--
perl -we 'for($i=$p=$s=1;$s!=$s+1/$p;print"f($i)=",$s+=1/($p*=$i++),"\n"){};'
Kevin J. Chase <k...@njcc.com> ``Do not suspect that I am not human.''
Colin Smith
>Can anyone suggest good sources of information regarding what "realistic"
>combat between spaceships might look like? By "realistic" I mean:
>
><A> respecting the laws of physics as they are currently understood
>
> be clearly extrapolated from existing technologies (fusion reactors,
> for instance, would be acceptable, but force fields and reactionless
> drives would not).
>
>would be gratefully accepted.
Not too sure, but I suspect that mass canon would be highly effective.
Accelerate a few thousand steel ballbearings up to 20,000mph and watch
them tear the target to pieces. Very difficult to counter.
--
|Colin Smith: Colin...@yelm.freeserve.co.uk | Windows 2000: |
|Windows 2000 is a REALLY dumb name for an OS!!! | The Zeppelin of |
|Linux is a MUCH better name for an OS! :-) | operating systems.|
John Rudd (yes, that's really my email address)
>
> Come to think of it...are there *any* good reasons to use energy weapons?
> energy weapons to dazzle, cook, or even vaporize incoming missles
> (particularly "smart" missles, which might be able to evade projectiles),
> but I think that G.D.W.'s "Traveller" rules hit the nail soundly on the
> head when they said that one very effective way to destroy a target is to
> deliver a substantial dose of kinetic energy with a bullet. Ordinary
> missles and railguns firing hybrid "missle-bullets" (with a limited
> ability to make course corrections) both seem pretty attractive.
>
> - J. Raynor
There's always the Traveler:2300 "one-shot" idea.. an energy weapon that
serves as the warhead for a missile. It's sort of an analog to the modern
shaped charge weapon which explodes some small distance away from teh
target and hits the target with the stream of molten metal from the shaped
warhead.
You do the same sort of thing with a low range high energy laser that is
built cheaply enough to be disposable, and put it on teh front a missile..
the missle only has to get close enough to provide the laser with a solid
chance to hit, then the laser fires.
--
John "kzin" Rudd kz...@domain.org http://www.domain.org/users/kzin
John Rudd (yes, that's really my email address)
>
> Accelerate a few thousand steel ballbearings up to 20,000mph and watch
> them tear the target to pieces. Very difficult to counter.
>
Only if you don't see them coming soon enough to generate enough delta-v to
make sure you don't pass through the cloud of bearings. The bearings
aren't going to change course, afterall. It's just an artificial
navigation hazard, really. If you find out about it soon enough to go
around it, you go around it.
Luke Campbell
> Ilkka Mannisto <iman...@cc.hut.fi> writes:
>
> > Why would the nukes be disallowed in the first place? Radiation really
> > isn't a problem in space, because no civilians will suffer from it, and
> > the ships probably will have some kind of protection against it.
>
> Give the lack of overpressure blast effects, nuclear warheads
> would need to be in virtual contact to have any of the destructive
> effects we visualize these types of weapons as having. You'd be
> better served by discarding the warhead, using the capacity for
> reaction mass, and going for a kinetic energy kill.
The heat radiation from nukes could cause problems at moderate ranges. Even if
it cannot melt through the ship's armor, the thermal effects could take out
surface equipment (antennae, turrets, sensors, and so on). If the thermal
effects are intense enough to vaporize the surface of the armor, you can get
explosive vaporization effects which could blow the hull apart. If I recall
correctly, the 10 to 20 kiloton bombs the U.S. was throwing around at the end of
WW II had a fireball somewhere between 50 and 100 meters across. This means that
even after radiation transport through the air is taken into account, the blast
photons packed enough energy to ionize the air at that distance. Without the air
absorbing all your x rays, you will have a much briefer, more intense thermal
pulse.
You could also use the nuke to pump a battery of x ray lasers. Another
possibility would be to try a sort of nuclear shaped charge explosive, that
directed much of its radiation and possibly vaporized debris in a narrow cone. I
once heard, somewhere, that the U.S. developed such a weapon, but have not heard
anything more about it since.
Luke
Luke Campbell
> I assume that missles and unmanned drones can consistently
> generate 10g or more acceleration. Manned ships are of course
> limited to 5g or less. Actually interplanetary or interstellar
> craft will be very large and dominated by fuel tanks. Smaller
> military vessels with comparatively short range would be the
> front line of fighting.
Using realistic thruster technology, I would think that long term
accelerations would be much lower than that, on the order of 0.01 g (for
fusion or nuclear-electric propulsion) or less (for ion drives or solar
sails). Short term accelerations could be very high (chemical rockets,
or by dumping reaction mass into the exhaust of your fusion drive), but
very wasteful of reaction mass, resulting in a lower overall change in
velocity before your reaction mass ran out. If you use too much
reaction mass in combat, you will never have enough to get home.
> A major point, noted in _Traveller 2300_, is that combat
> is very long-ranged, and an important part of the problem is
> *finding* the enemy.
True, but sensor technology determines whether the combat is over a
distance of light minutes or is confined to close orbit about a planet.
These two extremes result in very different types of combat. In the
former, combat is mostly a matter of launching self guided missiles and
waiting days or months (depending on thruster tech) for the missiles to
get close enough to the other ship, or for the enemies missiles to get
close enough to you. The latter results in a relatively fast paced
scenario where you manuever into favorable orbits, while throwing
kinetic energy kill vehicles or maybe nukes (from a gun, or self
propelled missiles) into the path of your target and targeting energy
weapons on your opponent (a 10 meter synthetic aperture focal array
could focus a visible violet laser beam into a 25 cm spot at
approximately one earth radius, a 10 cm aperature x-ray telescope could
focus an x ray laser with a photon energy of 12.5 keV into a half a
milimeter spot at aproximately one earth radius, both these could cause
damage to an enemy spacecraft with a high enough output, obviously, the
x-ray laser would need a shorter dwell time than the violet laser).
> A couple of general comments here:
>
> 1) Combat ships are liable to have a stable of decoys (which simulate
> the ship's IR and radar profile) and drones (remote sensor
> and weapons platforms). Manned fighters are unlikely since
> humans can't survive massive G-force accelerations.
Also, unmanned drones do not have to worry about whether they have
enough reaction mass to get back, they can use it all up in a mad dash
toward their target.
> 3) If opponent's are approaching each other, "combat" is slow as
> they face off at massive distances (i.e. 100,000 kilometers)
> just after detecting enemy presence. At this point, it is a
> fairly slow chess match of distinguishing the enemy from his
> drones and decoys.
Assuming, as I said, that they detect each other at around 100,000 km.
A spacecraft with a chemical rocket in operation should be fairly easy
to detect, it radiates lots of IR. A spacecraft with a solar sail would
stick out like a sore thumb. A spacecraft not under acceleration, or
powered by an ion or fusion drive would be much more difficult to find.
You could use a powerful radar or ladar to sweep for distant enemies,
but then you would be immediately identified by the signals your radar
or ladar was giving off, negating any possibility of sneaking up on or
past your adversary. You could, of course, put this in a drone, so at
least they wouldn't target you immediately, but as soon as they are
detected, they would probably start using active sensors, too, and you
would be found out.
Also, keep in mind that 100,000 km is only 1/3 of a light second, and a
125 keV x ray laser with a 10 cm aperature would have a spot size of
around 1 mm at this distance, allowing effective beam weapon targeting
and attacks.
Luke
Rachel Kronick
I'm trying to develop a semi-realistic SF RPG, and I do include
ship-to-ship combat in it. I agree that playing out a realistic
high-speed confrontation would be extremely boring for the PC's, or at
least for anyone playing a human. However, I'm toying with an idea that
(if a combat ever comes up in a game) will let the players actually take
a hand in starship combat.
It goes like this. To handle ship-to-ship combat, computer systems are
going to have to be amazingly fast and nimble, almost approaching full
creativity (I won't get into the artificial intelligence tangent here).
In fact, I think some creativity will be necessary to keep combat from
going automatically to the side with the biggest guns. And computers
themselves will probably be extremely efficient by that point (whatever
point ship-to-ship space combat takes place at). The computers will be
very sophisticated, and at least near-human in their capabilities.
So... The players will actually play the computers. But that doesn't
mean they have to act like mindless robots or whatever; they actually do
whatever they want, with all the sneakery and strategy that makes RPG's
fun, just keeping in mind that they are not portraying humans on a
human-like timescale, but rather computer control systems. It might
just be an excuse, but I think it's a rather good one. The
player-characters still end up with near-instant battle damage, but at
least the players feel like they are taking control of their own
destinies (which is a very big part of RPG's, in my opinion).
Anyway, just my idea...
-- Rachel Kronick
<http://www.geocities.com/jiawen6>
Tim wrote:
>
> >John P. Raynor <jra...@pantheon.yale.edu> wrote:
> : Can anyone suggest good sources of information regarding what "realistic"
> : combat between spaceships might look like? By "realistic" I mean:
>
> I'd say they'd be fairly sterile and passionless. Assuming large radius
> weapons, good targetting and decent propulsion systems, the PCs would be
> out of the loop, and assuming decent battle computers, so would the
> players.
>
> From a role-playing point of view, the PCs would be informed that their
> ship was damaged, and / or the opposing ships were damaged and retreated,
> or destroyed. No dogfighting.
>
> Think the bland passages recounting starship combat in "The Forever War".
>
> tim
Henry Penninkilampi
> >Can anyone suggest good sources of information regarding what "realistic"
> >combat between spaceships might look like? By "realistic" I mean:
> >
> ><A> respecting the laws of physics as they are currently understood
> >
> ><B> depending solely upon technologies which already exist, or which can
> > be clearly extrapolated from existing technologies (fusion reactors,
> > for instance, would be acceptable, but force fields and reactionless
> > drives would not).
> >
> >Any suggestions, including material which has nothing to do with gaming,
> >would be gratefully accepted.
>
> This has come up in rec.arts.sf.science...
> I've put some of the posts from those discussions on
> my webpage at <www.ionline.com/wobh/paq/paqtoc>.
And that would be:
<http://www.ionline.com/wobh/paq/paqtoc.htm>
...for those that want to check it out.
IMHO a little bit of understanding about Physics goes a long way in this
sort of scenario.
Since sensor technology would be so advanced, early-detection and
assessment would be pivotal. Potential conflicts will be preluded with a
barrage of sensor 'battles' in an attempt to find a weakness and then
uncover the true nature of the enemy (think about jousting - light, fast,
and points awarded to a breach of defence, not for damage scored).
The side that wins the sensor battle would then either leave the
battlefield, or attack - if your sensors have bought you a tactical
advantage, there's no point hanging around and giving your opponent a
chance to even the score. Thus the side with superior sensor technology
would decide whether or not there would even *be* a battle in the first
case.
If the side with better sensor technology also fancies their chances at a
victory *in actual combat* then they would engage. What this means is
that battles would, in most instances, be initiated by the side with a
*clear* advantage. All other things asided, that would make the average
battle very one-sided. Protacted engagements are highly unlikely to
occur, and resupplying front-line combatants would not be an issue.
As far as role-playing opportunities go, I think there aren't going to be
a heck of a lot of them. Human operated Star Wars/BattleStar
Galactica/Babylon 5 fighters just don't stand a chance against
computer-targetted energy weapons, so scrap the fighter-jock angle.
The ships would launch *swarms* of semi- or highly-intelligent self-guided
and propelled weapon systems (call them drones if you will, but missiles
with a very small approach profile (ie needle-shaped) would be more
likely). The best way to overcome point-defense systems is to simply give
the enemy too many targets to shoot at.
Battle Computers, not humans, would select apprach vectors for all ships
and weapon systems in order to optimise what will probably be the first
and *only* 'pass' (think about engagements between old cannon-equipped
sailing vessels, and how the first broadside salvo could cripple the
enemy - just make the cannon orders of magnitude more accurate, and have
over half mounted at the *front* of the ships).
Traveller uses a term, 'spinal-mount', to describe the main weapon systems
for a warship usually mounted along the spine of the ship. It's the
*range* and potency of these weapons that will probably decide the
outcome. The first side that can use one of these weapons to initiate a
successful attack will probably win. What these weapons are is a
different issue, whether they are energy weapons or massive 'rail-guns' is
anyone's guess.
One of the important points to remember is that huge warships would have
such a massive amount of momentum that they *can't* turn quickly. That
means that 'evasion' is *NOT* a really viable option. Warships (like
missiles) will be designed with the smallest approach profile possible
(Star Destroyers from Star Wars are illustrative). Thus for a ship to try
end 'take evasive action' and veer off an intercept course will result in
them exposing a much bigger portion of their ship to attack by the enemy's
main weapon system(s).
Like someone else said: It's like a game of chicken. The point at which
the weaker side's sensors and battle computer reveal that they have a
minimal chance of survival against the opponent's main weapon system is
when they will flinch and veer off course, put the foot down and try to
get the hell outta there! If they manage to detect that while *outside*
the effective range of the enemy's main weapon system, then they live. If
not, then they get gutted and die.
Think about massive black needles cruising through the blackness of space,
which launch swarms of other nasty little black needles when confronted,
and I think you're on the right path. Think about a sensor duel and then
a single, all-out frontal assault, and I think you're on the right path.
If I'm not mistaken, there's a few species of fish that live kilometers
below the surface of the ocean which look like this, and hunt like this.
It's not surprising that nature can give us a few pointers.
Henry.
Tim
1) no directed energy weapons such as 'lasers'
2) no ftl for either vessels nor projectiles
3) long range scanners (could be modified by decoys, but unlikely)
you could 'model' it with a card game where players playing the
battle computers (as someone suggested in another post) push moves
into a pipeline. More rudimentary computers have a longer pipeline
(they can't react as quickly), while more advanced ones have shorter.
Think the old 'nuke war | escalation | proliferation' game by F.B.I --
you put a card into a stack, then turn one over. In that game,
the pipeline length is set to be 1 card, but you could make one
where the lengths were around 5 cards at first, diminishing as
the vessels close range.
tim
Henry Penninkilampi
Colin...@Yelm.freeserve.co.uk wrote:
> Not too sure, but I suspect that mass canon would be highly effective.
>
> Accelerate a few thousand steel ballbearings up to 20,000mph and watch
> them tear the target to pieces. Very difficult to counter.
Naturally, you meant a dense, non-magnetic composite alloy which couldn't
be nudged off-course by a magnetic deflector, and which isn't rendered
extremely brittle by the temperature.
Henry.
Henry Penninkilampi
(John P. Raynor) wrote:
> Come to think of it...are there *any* good reasons to use energy weapons?
> The inverse-square law is such a huge disadvantage. I can see using
> energy weapons to dazzle, cook, or even vaporize incoming missles
> (particularly "smart" missles, which might be able to evade projectiles),
> but I think that G.D.W.'s "Traveller" rules hit the nail soundly on the
> head when they said that one very effective way to destroy a target is to
> deliver a substantial dose of kinetic energy with a bullet. Ordinary
> missles and railguns firing hybrid "missle-bullets" (with a limited
> ability to make course corrections) both seem pretty attractive.
There's not much subtlety in throwing a brick through the window of the
command deck on a Super Star Destroyer.
Point being: Energy weapons mounted on turrets are capable of surgical
precision by comparison to a mass-driver - making energy weapons essential
for the *capture* of an enemy vessel.
How many *years* did it take to build? How many *hours* did it take to
cripple and steal?
Henry.
William Clifford
email address)" <us...@domain.org> wrote:
>Colin Smith wrote:
>>
>> Accelerate a few thousand steel ballbearings up to 20,000mph and watch
>> them tear the target to pieces. Very difficult to counter.
>>
>
>Only if you don't see them coming soon enough to generate enough delta-v to
>make sure you don't pass through the cloud of bearings. The bearings
>aren't going to change course, afterall. It's just an artificial
>navigation hazard, really. If you find out about it soon enough to go
>around it, you go around it.
What you could use these for is to force the target to move into the
region where the guided missiles are. Carry a *lot* of buckshot with
you when you do this.
William Clifford
Penninkilampi) wrote:
>In article <38117ae9...@news.ionline.com>, wo...@yahoo.com wrote:
>> This has come up in rec.arts.sf.science...
>> I've put some of the posts from those discussions on
>> my webpage at <www.ionline.com/wobh/paq/paqtoc>.
>
>And that would be:
>
><http://www.ionline.com/wobh/paq/paqtoc.htm>
>
>...for those that want to check it out.
Doh! Sorry. I will fix that to be the index page. Then you won't be
able to miss it.
("Please type out 500 times 'I will always use copy and paste'...")
Scott Barrie
Penninkilampi) wrote:
>
>One of the important points to remember is that huge warships would have
>such a massive amount of momentum that they *can't* turn quickly. That
>means that 'evasion' is *NOT* a really viable option. Warships (like
>missiles) will be designed with the smallest approach profile possible
>(Star Destroyers from Star Wars are illustrative). Thus for a ship to try
>end 'take evasive action' and veer off an intercept course will result in
>them exposing a much bigger portion of their ship to attack by the enemy's
>main weapon system(s).
Can't they? Let's try to quantify that with some math.
Assume that two vessels spy each other at the same time, with one
meeting the other sidelong, like a "T" intersection. The first decides
to shoot, the other to evade.
How long does it take for the target to get out of the way?
Let's again assume that the target is 100m long, and can accelerate at
50 m/s/s (five "g"s) (how fast can you accelerate a human safely?),
and does so in a straight line forward. The additional displacement
caused by this unexpected acceleration is equal to (1/2)*a*t^2, or 25
t^2 (this doesn't count the entirely predictable displacement caused
by the ship's velocity at the time of the initial encounter). To
further displace itself by it's own length (100m) would take 2
seconds. Therefore if the encounter began with the ships at least 2
light seconds apart (600 000 km), then the target has a chance of
evasion. Closer than that the attacker will always hit the target
(assuming speed of light weapons, of course. Otherwise, dodging gets
even more likely).
Once you've dodged the first attack, further dodging becomes easier
because the image of your dodging takes time to reach the attacker,
during which time you're dodging further, effectively doubling your
time difference. The target could also choose to rotate a bit and
accelerate in a slightly different direction, but I imagine that the
critical distance would be of the same magnitude (varying on the
ship's dimensions and rotational acceleration).
So depending on the range of the weapons and sensors, evasion may or
may not be possible. Larger ships would have a larger critical
distance than smaller ships, but evasive action could still be called
for by large ships at times.
Similarly, if two vessels approach head on, then a vessel that could
accelerate sideways while maintaining the same facing could dodge an
incoming barrage (at a far enough distance). That would be a strange
sort of design, but it may be worthwhile if you're expecting this sort
of activity. Assuming a cylinder type shape, it would have a smaller
distance to move to dodge, plus the choice of two dimensions.
The key to winning extreme long range combat is the ability to
accelerate perpendicularly to your line of sight to your opponent.
That's my two cents, anyway.
Scott B. Barrie Physics Grad Student
ICQ: 31902206 Try the free Quest RPG
http://trollsden.physics.uwo.ca/quest.htm
John Rudd (yes, that's really my email address)
>
> Once you've dodged the first attack, further dodging becomes easier
> because the image of your dodging takes time to reach the attacker,
> during which time you're dodging further, effectively doubling your
> time difference. The target could also choose to rotate a bit and
> accelerate in a slightly different direction, but I imagine that the
> critical distance would be of the same magnitude (varying on the
> ship's dimensions and rotational acceleration).
>
I agree with what you said except for one thing...
You'd really _have_ to dodge in a different direction. If you just try to
dodge by speeding up (a straight line), you'd be making a predictable
course. It's not difficult to track an accellerating target with a
computer. It just takes a couple extra computing cycles to figure out how
much to lead the target by.
If you're dodging in a straight line, they'll know right where to shoot,
and you'll be right where they shoot. If you want to dodge, you'll have to
do things to not be where your velocity and accelleration vector right now
say where you'll be in 10 seconds.
PJS
Tim wrote in message <7uo6bv$eci$1...@nntp8.atl.mindspring.net>...
>>John P. Raynor <jra...@pantheon.yale.edu> wrote:
>: Can anyone suggest good sources of information regarding what "realistic"
>: combat between spaceships might look like? By "realistic" I mean:
>
>weapons, good targetting and decent propulsion systems, the PCs would be
>out of the loop, and assuming decent battle computers, so would the
>players.
>
>From a role-playing point of view, the PCs would be informed that their
>ship was damaged, and / or the opposing ships were damaged and retreated,
>or destroyed. No dogfighting.
>
>Think the bland passages recounting starship combat in "The Forever War".
A few years ago there was a computer game "Mantis" which featured realistic
space combat . . . and it was incredibly dull.
---
Puritanism - the haunting fear that someone, somewhere
may be happy.
- H.L. Mencken
PJS
>Timothy J. Miller <timothy...@afiwc01.af.mil> wrote:
>: Give the lack of overpressure blast effects, nuclear warheads
>: would need to be in virtual contact to have any of the destructive
>: effects we visualize these types of weapons as having. You'd be
>: better served by discarding the warhead, using the capacity for
>: reaction mass, and going for a kinetic energy kill.
>
>would provide more enrgy than an equivalent mass of chemical rocket fuel.
-------------
...and wouldn't the electro-magnetic pulse from the blast do some damage to
electronics?
Colin Smith
>In article <slrn811pp...@Orlanth.homenetwork>,
>Colin...@Yelm.freeserve.co.uk wrote:
>
>> Not too sure, but I suspect that mass canon would be highly effective.
>>
>> them tear the target to pieces. Very difficult to counter.
>
>be nudged off-course by a magnetic deflector, and which isn't rendered
>extremely brittle by the temperature.
Naturally. Depleted Uranium?
Colin Smith
>On Fri, 22 Oct 1999 18:37:15 -0700, "John Rudd (yes, that's really my
>email address)" <us...@domain.org> wrote:
>
>>Colin Smith wrote:
>>>
>>> them tear the target to pieces. Very difficult to counter.
>>>
>>
>>make sure you don't pass through the cloud of bearings. The bearings
>>aren't going to change course, afterall. It's just an artificial
>>navigation hazard, really. If you find out about it soon enough to go
>>around it, you go around it.
>
>What you could use these for is to force the target to move into the
>region where the guided missiles are. Carry a *lot* of buckshot with
>you when you do this.
People shoot guided missiles down with canons right now.
Bullets/ballbearings are cheaper.
--
|Colin Smith: Colin...@yelm.freeserve.co.uk | Windows 2000: |
|The Archeus FRPG system: | The Zeppelin of |
|http://www.yelm.freeserve.co.uk/archeus/ | operating systems.|
Scott Barrie
email address)" <us...@domain.org> wrote:
>Scott Barrie wrote:
>>
>> Once you've dodged the first attack, further dodging becomes easier
>> because the image of your dodging takes time to reach the attacker,
>> during which time you're dodging further, effectively doubling your
>> time difference. The target could also choose to rotate a bit and
>> accelerate in a slightly different direction, but I imagine that the
>> critical distance would be of the same magnitude (varying on the
>> ship's dimensions and rotational acceleration).
>>
>
>I agree with what you said except for one thing...
>
>You'd really _have_ to dodge in a different direction. If you just try to
>dodge by speeding up (a straight line), you'd be making a predictable
>course. It's not difficult to track an accellerating target with a
>computer. It just takes a couple extra computing cycles to figure out how
>much to lead the target by.
>
>If you're dodging in a straight line, they'll know right where to shoot,
>and you'll be right where they shoot. If you want to dodge, you'll have to
>do things to not be where your velocity and accelleration vector right now
>say where you'll be in 10 seconds.
But you can also choose not to accelerate, in which case if they
assume that you will accelerate, they'll miss.
Hence when you're beyond a critical range, you have a chance to dodge,
not a certainty of dodging.
Luke Campbell
> In article <dwMP3.742$pp1....@dfw-read.news.verio.net>, Jim Walters
> <jwal...@shell.clark.net> writes:
>
> >In either case, you will need to find some source on celestial mechanics.
> >Some of the effects are non-intuitive. For example, if you are orbiting a
> >planet and speed up, it will take you longer to get to the other side of
> >the planet than if you stayed the same speed you are now.
>
> Explain that one to me. I can see it being true in some circumstances, but not
> all.
If you spped up, it increases your orbital energy. With increased orbital
energy, you go into a higher orbit, which takes longer to get back where it
started. (Note that this higher energy orbit might be highly eliptical, with the
low part near where you changed your velocity. It is still a slower orbit).
Luke
Luke Campbell
> ...and wouldn't the electro-magnetic pulse from the blast do some damage to
> electronics?
The EMP effect is caused by gamma rays from the blast knocking electrons off
air molecules. The free electrons gyrate around the earth's magnetic field
lines, producing a powerful pulse of microwaves with electric fields high
enough to fry transistors and other electronic components. In space, there is
no air to knock the electrons off of.
The ionizing radiation (gamma rays, mostly) from the pulse can still fry
electronics, but I do not know the relative effectiveness of the two methods.
Luke
Luke Campbell
> Come to think of it...are there *any* good reasons to use energy weapons?
> The inverse-square law is such a huge disadvantage. I can see using
> energy weapons to dazzle, cook, or even vaporize incoming missles
> (particularly "smart" missles, which might be able to evade projectiles),
> but I think that G.D.W.'s "Traveller" rules hit the nail soundly on the
> head when they said that one very effective way to destroy a target is to
> deliver a substantial dose of kinetic energy with a bullet. Ordinary
> missles and railguns firing hybrid "missle-bullets" (with a limited
> ability to make course corrections) both seem pretty attractive.
>
> - J. Raynor
With x-ray lasers and particle beams, the focusing technology, in principle,
can be good enough to deliver a very intense beam at long ranges. As an
example, consider a laser that emits 12.5 keV photons (1 angstrom
wavelength), with a 1 meter focusing array. The divergence angle will then
be on the order of 10^-10 radians. (1.22 * 10^-10 radians for the central
difraction spot). At a distance of 100,000 kilometers, the x-rays can be
focused into about a 12 cm spot. (I think I over-estimated this in a
previous post by two orders of magnitude.) Given a sufficient beam energy,
this could cause significant damage. The beam could be rapidly focused and
targeted with precision. The main limitation is the speed of light delay.
At 100,000 km, that is 1/3 of a second for information to get from your
target to you, and 1/3 of a second for the beam to get from you to your
target. If your adversary can maneuver significantly in 2/3 of a second,
and you cannot predict his movement, your beam could still miss. Of course,
the high acceleration manuevers needed for this sort of thing would be very
wasteful of reaction mass, so your opponent might well use up so much
reaction mass that he can no longer reach his objective, and you win.
Scott Barrie
Penninkilampi) wrote:
>In article <WZoROAiplBI=hcoCAKbl...@4ax.com>, Scott Barrie
><sba...@julian.uwo.ca> wrote:
>
>> >One of the important points to remember is that huge warships would have
>> >such a massive amount of momentum that they *can't* turn quickly. That
>> >means that 'evasion' is *NOT* a really viable option.
>...
>> Can't they? Let's try to quantify that with some math.
>>
>> Assume that two vessels spy each other at the same time, with one
>> meeting the other sidelong, like a "T" intersection. The first decides
>> to shoot, the other to evade.
>>
>> How long does it take for the target to get out of the way?
>>
>> Let's again assume that the target is 100m long, and can accelerate at
>> 50 m/s/s (five "g"s) (how fast can you accelerate a human safely?),
>> and does so in a straight line forward. The additional displacement
>> caused by this unexpected acceleration is equal to (1/2)*a*t^2, or 25
>> t^2 (this doesn't count the entirely predictable displacement caused
>> by the ship's velocity at the time of the initial encounter). To
>> further displace itself by it's own length (100m) would take 2
>> seconds. Therefore if the encounter began with the ships at least 2
>> light seconds apart (600 000 km), then the target has a chance of
>> evasion. Closer than that the attacker will always hit the target
>> (assuming speed of light weapons, of course. Otherwise, dodging gets
>> even more likely).
>
>...and you've just made the classic mistake of assuming that the
>'attacker' doesn't have a competent battle computer that factors in the
>slightest deviation off-course and then *compensates* for it.
>
>"Any thing you can do, I can do.."
How can they compensate for it? If the craft doesn't accelerate, it's
at position X. If it does, it's at position X+100. So where do you
aim? It becomes a guessing game. Computers can't predict the future,
nor can they alter a shot already fired.
>Question: With speed-of-light weapons, how can you even *attempt* to
>evade an attack that you have *NO WAY* of detecting before it actually
>hits? You DON'T. That just leaves you with one option: To *continually*
>engage in 'random' evasive maneuvers which effect the largest
>displacements in your profile.
There exists a point in time when you spy the enemy. Start dodging and
shooting then, assuming that they have spotted you as well. If they
didn't, you should get an early hit. If they spied you first, then
their attack is probably on it's way. If you're closer than your
critical distance, don't bother with evasion, just shoot shoot shoot.
>> Once you've dodged the first attack, further dodging becomes easier
>
>No, it doesn't. Your evasive maneuvers have created their own momentum
>(along the plane perpendicular to approach) which then must be *countered*
>in order to produce another *effective* evasive shift in your profile.
No, it does not. You are perfectly capable of accelerating in any
direction without first countering any previous momentum changes.
>Going faster makes you *easier* to hit because your course is more
>predictable because you have more momentum which takes longer to negate.
What makes you think this? Do you play Space Master, by any chance?
They propose something like this to simplify their space combat rules.
Anyway, once the attacker spies that the target has changed velocity,
they can now again predict where the target would be with no
acceleration. The target can therefore be up to a distance
(1/2)a(2t)^2 away from that point (where t is the time it takes light
to travel from attacker to target), in whatever direction "a" is in.
But the attacker doesn't know what direction (if any) the target
chose/will choose to accelerate in during that time 2t. The plume of
exhaust the attacker sees at the time could change anytime after the
shot is fired.
Acceleration is the key to being unpredictable. Velocity and momentum
have nothing to do with it.
>Furthermore: It makes it *trivial* for the enemy to establish a
>weapons-lock on your ship with even primitive targetting systems like
>infra-red. No point in having fancy ECM if a massive thrust plume
>effectively points out your ship against the blackness of space.
And the time between when they see the plume and when their attack can
hit where you will therefore be is now twice the time it takes light
to traverse the distance. I'm considering extreme distances here,
where the speed of light is a factor.
>> Similarly, if two vessels approach head on, then a vessel that could
>> accelerate sideways while maintaining the same facing could dodge an
>> incoming barrage (at a far enough distance). That would be a strange
>> sort of design, but it may be worthwhile if you're expecting this sort
>> of activity. Assuming a cylinder type shape, it would have a smaller
>> distance to move to dodge, plus the choice of two dimensions.
>
>A sphere with six drive thrusters along the axes (and a number of
>mini-thrusters for orientation) would probably rate as one of the more
>*effective* designs for evasive purposes. The problem is that a sphere is
>also one of the easiest shapes to hit, and one of the hardest shapes to
>armour. That makes you hard to hit, but when you do get hit, you die.
>
>This relationship is what you would espect: That the ability to avoid an
>attack is inversely proportional to the ability to survive it.
>
>A needle shape, on the other hand, has the majority of it's hull at an
>angle of around 80 degrees from the perpendicular which means that, for
>the same incident area, an energy weapon will strike on over *SIX* times
>more armour. This means that (for the most part) energy weapons are six
>times *less* effective against a needle than a sphere.
<many excellent engineering points snipped>
Try a needle shape that can vent it's reaction mass sideways, and at
different positions along it's length. It could then accelerate to
dodge, while keeping it's business end pointed towards the enemy. I'll
leave the precise design of such a ship as a project for future
generations. <g> We are talking science fiction, and I have confidence
in the ingenuity of man. An engine doesn't have to be laid out in the
same direction as it will generate thrust, nor does a ship need
separate engines for each possible direction.
I believe that such a craft would have an advantage over a simpler,
more heavily armed opponent at extreme ranges. At close range it's
toast, of course. At either range, it'll burn up more fuel. The
question is at what point is survivability worth the extra fuel?
Depends on the setting, I suppose (expense of ships (including crew
and cargo) vs expense of fuel, plus sensor range and weapon range).
John Rudd (yes, that's really my email address)
>
> On Sat, 23 Oct 1999 07:50:03 -0700, "John Rudd (yes, that's really my
> email address)" <us...@domain.org> wrote:
>
> >Scott Barrie wrote:
> >>
> >> during which time you're dodging further, effectively doubling your
> >> time difference. The target could also choose to rotate a bit and
> >> accelerate in a slightly different direction, but I imagine that the
> >> critical distance would be of the same magnitude (varying on the
> >> ship's dimensions and rotational acceleration).
> >>
> >
> >I agree with what you said except for one thing...
> >
> >You'd really _have_ to dodge in a different direction. If you just try to
> >dodge by speeding up (a straight line), you'd be making a predictable
> >course. It's not difficult to track an accellerating target with a
> >computer. It just takes a couple extra computing cycles to figure out how
> >much to lead the target by.
> >
> >If you're dodging in a straight line, they'll know right where to shoot,
> >and you'll be right where they shoot. If you want to dodge, you'll have to
> >do things to not be where your velocity and accelleration vector right now
> >say where you'll be in 10 seconds.
>
> But you can also choose not to accelerate, in which case if they
> assume that you will accelerate, they'll miss.
>
> Hence when you're beyond a critical range, you have a chance to dodge,
> not a certainty of dodging.
>
In which case you send a cloud of pebbles that has a shotgun like spread
that matches the width of their ship, and covers everywhere along their
velocity venctor that matches what you think they may be based upon their
maximum accel and decel. If they aren't moving across their velocity
vector, but merely varying accelleration and decelleration along their
current direction of movement, it's just a matter of observing and guessing
their maximum thrust ability.
If it's something predictable, like you're fighting a war against a race
with a standard fleet of warships (sort of like how we currently
manufacture ships in "classes" that all have the same general performance
range), then you're likely to have built up a library of observed thrust
characteristics of your opponents ships. Thus, you know in advance,
without prolonged observation of thrust, what the spread of your pebble
cloud needs to be as soon as you've identified their ship.
Henry Penninkilampi
> >One of the important points to remember is that huge warships would have
> >such a massive amount of momentum that they *can't* turn quickly. That
> >means that 'evasion' is *NOT* a really viable option.
...
> Can't they? Let's try to quantify that with some math.
>
> Assume that two vessels spy each other at the same time, with one
> meeting the other sidelong, like a "T" intersection. The first decides
> to shoot, the other to evade.
>
> How long does it take for the target to get out of the way?
>
> Let's again assume that the target is 100m long, and can accelerate at
> 50 m/s/s (five "g"s) (how fast can you accelerate a human safely?),
> and does so in a straight line forward. The additional displacement
> caused by this unexpected acceleration is equal to (1/2)*a*t^2, or 25
> t^2 (this doesn't count the entirely predictable displacement caused
> by the ship's velocity at the time of the initial encounter). To
> further displace itself by it's own length (100m) would take 2
> seconds. Therefore if the encounter began with the ships at least 2
> light seconds apart (600 000 km), then the target has a chance of
> evasion. Closer than that the attacker will always hit the target
> (assuming speed of light weapons, of course. Otherwise, dodging gets
> even more likely).
...and you've just made the classic mistake of assuming that the
'attacker' doesn't have a competent battle computer that factors in the
slightest deviation off-course and then *compensates* for it.
"Any thing you can do, I can do.."
Question: With speed-of-light weapons, how can you even *attempt* to
evade an attack that you have *NO WAY* of detecting before it actually
hits? You DON'T. That just leaves you with one option: To *continually*
engage in 'random' evasive maneuvers which effect the largest
displacements in your profile.
Furthermore: All this maneuvering will chew up an *amazing* amount of fuel.
> Once you've dodged the first attack, further dodging becomes easier
No, it doesn't. Your evasive maneuvers have created their own momentum
(along the plane perpendicular to approach) which then must be *countered*
in order to produce another *effective* evasive shift in your profile.
Going faster makes you *easier* to hit because your course is more
predictable because you have more momentum which takes longer to negate.
Furthermore: It makes it *trivial* for the enemy to establish a
weapons-lock on your ship with even primitive targetting systems like
infra-red. No point in having fancy ECM if a massive thrust plume
effectively points out your ship against the blackness of space.
> Similarly, if two vessels approach head on, then a vessel that could
> accelerate sideways while maintaining the same facing could dodge an
> incoming barrage (at a far enough distance). That would be a strange
> sort of design, but it may be worthwhile if you're expecting this sort
> of activity. Assuming a cylinder type shape, it would have a smaller
> distance to move to dodge, plus the choice of two dimensions.
A sphere with six drive thrusters along the axes (and a number of
mini-thrusters for orientation) would probably rate as one of the more
*effective* designs for evasive purposes. The problem is that a sphere is
also one of the easiest shapes to hit, and one of the hardest shapes to
armour. That makes you hard to hit, but when you do get hit, you die.
This relationship is what you would espect: That the ability to avoid an
attack is inversely proportional to the ability to survive it.
A needle shape, on the other hand, has the majority of it's hull at an
angle of around 80 degrees from the perpendicular which means that, for
the same incident area, an energy weapon will strike on over *SIX* times
more armour. This means that (for the most part) energy weapons are six
times *less* effective against a needle than a sphere.
Another problem with effective evasive maneuvers is that the thrust that
needs to be applied is perpendicular to the (normal) structural integrity
axis of the craft. Strap a jet engine on the wingtip of a Boeing, point
it towards the cabin, fire it, and see how many seconds it takes the plane
to disintergrate and crash. Now, I know that it's common sense to
strengthen the craft to withstand the forces of evasive maneuvers, but...
When you consider the amount of extra structural reinforcement that you
will need, the additional thrusters that you will need, the massive
amounts of fuel that you will need, the larger profile that you will be
presenting, and the decreased effectiveness of armour, it just makes far,
far, FAR more sense to just leave the engines at the back, present as
small a profile to the enemy as possible, stack on as much armour as
possible, and then rely on those extra 10 Super-Fugly Guns mounted up
front (instead of bigger fuel tanks) to pound the crap out of the other
guys and win the day.
> The key to winning extreme long range combat is the ability to
> accelerate perpendicularly to your line of sight to your opponent.
Correction: The key to *avoiding being hit* at extreme long range is the
ability to accelerate perpendicularly to your line of sight to your
opponent. The key to *winning* combat is the ability to get close enough,
fast enough, and with enough guns, to be able to deliver an assault from
which the enemy has no hope of recovery.
Making your craft an agile, floating fuel-tank with thrusters on all sides
makes it a *probe* not a *warship*.
Henry.
Henry Penninkilampi
Colin...@Yelm.freeserve.co.uk wrote:
> >> Accelerate a few thousand steel ballbearings up to 20,000mph and watch
> >> them tear the target to pieces. Very difficult to counter.
> >
> >Naturally, you meant a dense, non-magnetic composite alloy which couldn't
> >be nudged off-course by a magnetic deflector, and which isn't rendered
> >extremely brittle by the temperature.
>
> Naturally. Depleted Uranium?
Or an ice-hockey puck.
There's a man-portable 'gauss rifle'-type weapon developed by the US
military years ago which chews up something awfully like an ice-hockey
puck into small slivers in a rotating chamber and accelerates the shavings
down the barrel. Made an absolute mess of a 1' thick (concrete?) wall
that they fired it at in the demo. The puck was around 85% plastic!
Remember that kinetic energy is proportional to mass, but it's also
proportional to speed *squared*, so it is far, far more important to have
*fast* projectiles than heavy ones.
(Hmmm... Missile cruisers named after Canadian ice-hockey teams... I can
see it now! ;)
I saw a program a few years ago (a British documentary on the US SDI
Initiative) which outlined a number of neat weapon systems under
consideration. One was pressurised thermal chamber into which you fed a
combination of materials (solids, liquids and gasses) which, under the
right temperature and pressure conditions created a molten liquid which
was magnetic, but which (when it cools and solidifies) loses it's magnetic
properties.
The theory: Mix a vat of the liquid, bleed it into an accelerator as a
magnetic stream, and then shoot it at a target at some absurd speed. Once
it exits the accelerator it hits space, forms into
droplets/shrapnel/whatever as it cools, and then loses it's magnetic
properties. Enough to rain on anyone's parade! :)
The systems main advantage (apart from the obvious) was, IIRC, that it had
far less moving parts than a conventional rail-gun-type apparatus with a
solid shot feed mechanism, and as a result was far less likely to have
something 'jam'.
(Just thought I'd mention that one for those of you that had fun playing
with hoses and sprinklers when you were kids, but who don't realise how
lethal a weapon they become when you put them in space.)
Henry.
Justin Bacon
<jwal...@shell.clark.net> writes:
>In either case, you will need to find some source on celestial mechanics.
>Some of the effects are non-intuitive. For example, if you are orbiting a
>planet and speed up, it will take you longer to get to the other side of
>the planet than if you stayed the same speed you are now.
Explain that one to me. I can see it being true in some circumstances, but not
all.
Justin Bacon
tr...@prairie.lakes.com
Scott Barrie
On Sat, 23 Oct 1999 21:06:11 -0700, "John Rudd" <us...@domain.org>
wrote:
>Scott Barrie wrote:
>> >> during which time you're dodging further, effectively doubling your
>> >> time difference. The target could also choose to rotate a bit and
>> >> accelerate in a slightly different direction, but I imagine that the
>> >> critical distance would be of the same magnitude (varying on the
>> >> ship's dimensions and rotational acceleration).
>> >
>> >I agree with what you said except for one thing...
>> >
>> >You'd really _have_ to dodge in a different direction. If you just try to
>> >dodge by speeding up (a straight line), you'd be making a predictable
>> >course. It's not difficult to track an accellerating target with a
>> >computer. It just takes a couple extra computing cycles to figure out how
>> >much to lead the target by.
>>
>> assume that you will accelerate, they'll miss.
>>
>> Hence when you're beyond a critical range, you have a chance to dodge,
>> not a certainty of dodging.
>
>In which case you send a cloud of pebbles that has a shotgun like spread
>that matches the width of their ship, and covers everywhere along their
>velocity venctor that matches what you think they may be based upon their
>maximum accel and decel. If they aren't moving across their velocity
>vector, but merely varying accelleration and decelleration along their
>current direction of movement, it's just a matter of observing and guessing
>their maximum thrust ability.
Yes, that would work. I was postulating a laser-like weapon, used at
extreme distances. Buckshot would naturally move at somewhat slower
than c.
I certainly agree that changing directions is a good idea. However, I
think my two dimensional approximation is sufficient to form an idea
of what is required to dodge a suspected light speed attack.
>If it's something predictable, like you're fighting a war against a race
>with a standard fleet of warships (sort of like how we currently
>manufacture ships in "classes" that all have the same general performance
>range), then you're likely to have built up a library of observed thrust
>characteristics of your opponents ships. Thus, you know in advance,
>without prolonged observation of thrust, what the spread of your pebble
>cloud needs to be as soon as you've identified their ship.
No argument here.
Thomas Bagwell
RPG, I recommend checking out the tabletop game 'Slag!' by BTRC. It's a
very simple, inexpensive ($8 US, less if you download the PDF version)
system that uses diceless resolution in a way that makes sense. You can
design any type of ship, and a wide range of common SF types of weapons
are included. Play is very quick. I use it in conjunction with CORPS
for my SF campaign. (For necessary roleplaying detail, I designed the
ships using BTRC's _Vehicle Design System_, and can use CORPS rules for
combat if I need a lot more detail.)
Tom B.
Nikolaj Lemche
> Yes, that would work. I was postulating a laser-like weapon, used at
> extreme distances. Buckshot would naturally move at somewhat slower
> than c.
But you could also use a detonation laser with scores or even hundreds of
rods.
Nikolaj Lemche
------------------------------------------------
E-mail: nik...@mail1.stofanet.dk
Homepage: http://members.xoom.com/Kuranov/
Psychohist
...and you've just made the classic mistake of assuming that the
'attacker' doesn't have a competent battle computer that factors in the
slightest deviation off-course and then *compensates* for it.
No, Scott is right. No matter how sophisticated the attacker's computer, it is
still subject to speed of light lag; it can't know about what the defender is
doing until the photons emitted by the defender get to the attacker.
Warren
Psychohist
What you could use these for is to force the target to move into the
region where the guided missiles are. Carry a *lot* of buckshot with
you when you do this.
I'm also not completely convinced of the effectiveness of ball bearing in the
first place.
The idea behind them is to pack enough kinetic energy into them that they
essentially generate a small explosion when they hit the ship, which is enough
to tear a sizable hole in the hull.
That works - for the outer hull. But an inner hull a few feet deeper will be
harder to affect, since the 'blast' from the initial impact attenuates rapidly,
especially if the two hulls are separated by vacuum.
Now, if the ball bearing are going at near light speed, rather than a mere
20,000 mph, a second hull may not help much. But how do you get them up to
near light speed in the first place?
Warren
Frank J. Perricone
address)" <us...@domain.org> wrote:
> If it's something predictable, like you're fighting a war against a race
> with a standard fleet of warships (sort of like how we currently
> manufacture ships in "classes" that all have the same general performance
> range), then you're likely to have built up a library of observed thrust
> characteristics of your opponents ships. Thus, you know in advance,
> without prolonged observation of thrust, what the spread of your pebble
> cloud needs to be as soon as you've identified their ship.
And then your computers are trying to match their ship's signature to
determine both its capabilities and its computer's most likely strategies,
and their computer is trying to guess what your computer is going to
predict for its strategies and do something different -- or fool it into
thinking it's going to use a different strategy than it is. If high-speed
communication exists, both computers might be linked to third parties that
are selling up-to-the-second analyses of what strategies other computers
are using to accomplish both offense and defense in these battles. And of
course there might be still more computers trying to break past the
security systems around all these communications; after all, if you can get
into the computer system of that other ship, you could find out what it's
going to do, or feed it false information. (And of course they might want
to make you think you successfully broke in and feed you false information.
And so on...)
--
* Frank J. Perricone * hawt...@sover.net * http://www.sover.net/~hawthorn
Prism: http://www.sover.net/~hawthorn/Prism/
Just because we aren't all the same doesn't mean we have nothing in common
Just because we have something in common doesn't mean we're all the same
Torben AEgidius Mogensen
This all depends on the nature of the two powers that fight. If they
are from different planetary systems, they will have accelerated their
ships up to a significant fraction of C just to reach each other. This
means that anything you shoot out will have massive kinetic energy
relative to the enemy even if you only add a little to it when you
shoot it (just enough to target it).
If you really want to go to war against some other race, you wouldn't
do combat in space, you would just accelerate a mass to very high
velocity and crash it into their home planet. You can do that by using
a solar sail to pull it out of your own system (and add extra push to
this sail with particle guns). If you have a ball of dense,
nonreflecting material that won't emit significant radiation when hit
by solar wind at the speed it will be approaching the target system,
it will be very hard to detect. A 1m diameter ball of lead or iron
travelling at 0.01 C will do a lot of damage if it hits an Earth-like
planet.
Basically, what I'm saying is that you would do battle without ever
leaving your home planet and you would target the enemy home planet
directly.
Torben Mogensen (tor...@diku.dk)
Jim Walters
: Jim Walters <jwal...@shell.clark.net> wrote:
:>It depends on the technology you will be using. Are you going to be
:>using fairly advanced technologies like Bussard ramjet type spacecraft?
:>(It's a relatively fast STL ship which collects interstellar hydrogen
:>with a magnetic field, and then burns it in a fusion reactor. We are
:>at least a century away from actually building one, but I think it is
:>theoretically possible.)
: Actually, I think this one has already been ruled out. Given
: the scarcity of interstellar hydrogen, I believe it can be shown that
: the amount of energy is takes to collect the hydrogen is *less* than the
: energy that could possibly be gained by fusing it.
: I haven't done the calculation, myself, although I suppose I
: could. The mean interstellar abundance of hydrogen is about
: 0.05 protons per cm^-3. The energy gained by fusing protons
: is at most about 5 MeV per nucleon, I think. Now the hydrogen
: has to be collected before the ship passes (although for a slow
: ship the energy limit will be from the hydrogen temperature, which
: I can't find right now).
: It's actually been suggested that the ramjet might be extremely
: useful for interstellar travel as a *brake*, so that the spaceship
: doesn't need to bring reaction mass to slow itself down upon reaching
: its destination.
OK. The last I had heard (and it's been about 10 years since I paid much
attention to it) the drive was possible, but that drag would limit speed
to about 0.1 c.
--
Jim Walters jwal...@clark.net
"My race is pacifist and does not believe in war.
We kill only out of personal spite." Brain Guy - MST3K
Jim Walters
: In article <dwMP3.742$pp1....@dfw-read.news.verio.net>, Jim Walters
: <jwal...@shell.clark.net> writes:
It's Kepler's Third Law. It basically says that the square of your
orbital period is proportional to your mean distance from the object you
are orbiting.
As you increase your velocity, you go into a higher orbit. (The shape of
the new orbit depends upon where in the orbit you fired your motor.) The
higher your orbit, the longer it takes to make a full orbit. For example,
when a GOES weather satellite is launched, the rocket places it in a
highly elliptical orbit with a period of between 12 and 13 hours. The
highest point in the orbit is close to where they want it, but the lowest
point in the orbit is far too close to the earth. There is then a series
of maneuvers to bring the satellite where they want it. The satellites
main thruster is fired at the highest point in the orbit to increase the
satellite's velocity. This has the effect of raising the lowest point in
the orbit to the desired altitude. When everthing is done, the satellite
is in a high orbit with a period of 24 hours.
Jim Walters
: It's Kepler's Third Law. It basically says that the square of your
: orbital period is proportional to your mean distance from the object you
: are orbiting.
Oops. I meant to say the cube of your mean distance.
Marc Lombart
Justin Bacon wrote in message
<19991023203439...@ngol03.aol.com>...
>In article <dwMP3.742$pp1....@dfw-read.news.verio.net>, Jim Walters
><jwal...@shell.clark.net> writes:
>
>>In either case, you will need to find some source on celestial mechanics.
>>Some of the effects are non-intuitive. For example, if you are orbiting a
>>planet and speed up, it will take you longer to get to the other side of
>>the planet than if you stayed the same speed you are now.
>
>Explain that one to me. I can see it being true in some circumstances, but
not
>all.
'tis true, but badly stated. It is not that you increase your velocity,
but that you accelerate. This acceleration, or DeltaV [DeltaV vs
acceleration, because the time it takes you to change the velocity is
irrelevant] cause you to go into a higher orbit. Thereby increasing the time
it takes to circle the planet, look at the Moon versus a Geostationary
satelite, vs a low Earth orbit satelite.
Marc
Jim Davies
Penninkilampi) wrote:
>Question: With speed-of-light weapons, how can you even *attempt* to
>evade an attack that you have *NO WAY* of detecting before it actually
>hits? You DON'T. That just leaves you with one option: To *continually*
>engage in 'random' evasive maneuvers which effect the largest
>displacements in your profile.
>
>Furthermore: All this maneuvering will chew up an *amazing* amount of fuel.
What you want is two (or more) heavy objects on the ends of long bits
of elastic. Chuck them out of the ship so that the whole ensemble
starts to oscillate chaotically (that's why you have 2 lumps - it's a
3-body problem) around its centre of mass. You don't actually use any
fuel to dodge except for the initial energy to get them moving. Alter
the tension on the elastic now and again to confuse the enemy
targeting system.
Jim Davies
------------------------------------------
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PJS
Luke Campbell wrote in message <381261B6...@u.washington.edu>...
Wouldn't the surface of the ship and the air inside it provide enough stuff
to ionise?
John Rudd (yes, that's really my email address)
>
> Henry Penninkilampi posts, in part:
>
> 'attacker' doesn't have a competent battle computer that factors in the
> slightest deviation off-course and then *compensates* for it.
>
> still subject to speed of light lag; it can't know about what the defender is
> doing until the photons emitted by the defender get to the attacker.
>
> Warren
No, but it can project a light cone* (a cone of possible movement points
that the target can reach in the next N seconds (where N seconds is how
long it will take your weapon to reach them, given the distance to the
target) out from the defender's current position, momentum, and maximum
(observed or known) thrust) for the defender's ship.
How you use that light cone depends on what kinds of weapons you have.
High rate of fire lasers or lots of "one shot" missiles: pepper the
highest probability parts of the light cone with volleys from your lasers,
and if you have enough volleys available, you start spreading your shots
out to the lower probability areas as well.
Pebble casters or "shotgun" missiles: create a spread of pebbles to
saturate the light cone as much as you can with high velocity matter.
Part of the problem with this thought exercise is that most of the people
I've seen posting are all from a country which takes the "precision
munitions" philosophy of warfare ... we engineer devices like the Phalanx
CIWS and Goalkeeper (UK version) to put bullets _right_at_the_target_,
which requires a LOT of near-instantaenous information and computation.
The alternative, as seen by several of the Soveit design anti-aircraft
systems, is "throw up a wall of lead, and watch what happens when they fly
through it", which requires far less computation and not-as-instantaneous
information. Both methods work, assuming each gets enough information and
computational ability.
In Space, the problem goes to huge extremes because it's impossible to get
anything near "instantaneous information" unless you're at a trivially
short distance (which, for modern warfare, you pretty much are at trivially
short distances, for comparison to sub-light space warfare). You have to
start thinking much more in the "wall of lead" mindest, because it's
prohibitively difficult to try to build weapons under the "precision
munitions" mindset.
More likely than not, trying to figure out how to place a single well-aimed
shot is going to be so difficult that it's just not worth it. SO, the only
practical way to make up for the fact that the defender can move to almost
anyplace within his light cone is to fill his light cone with weaponry.
The problem becomes one of having plentiful, cheap, but lethal weapons
(pebbles that move fast enough to be devastating to anything they hit, yet
that have a lifetime so that they don't injure unintended targets if they
miss the primary target, straight fire missiles with shotgun or oneshot
warheads that will self destruct after a certain period of time, beam
weapons that can keep a reasonable power at a reasonable range, but
dissipate at further ranges, etc), and having just enough information about
the target to compute reasonable light cones.
(* light cone actually referes to the possible places an object can get to
if its moving at the speed of light, given time. It's a cone when you
compare position on one axis vs time .... but in 3 space, it's more like a
bubble, but the bubble is stretched according to the targets momentum and
thrust capabilities. You would actually end up with something more like a
tear drop shape...
time
|
| \ /
| \ /
| \ / <--- "movement" cone
| \ /
| \ /
| * <--- initial position
|
+---------------- distance
If the slope of the lines correspond to the speed of light, then that's a
light cone... Given real engineering design principles, you can recognize
that the cone will always be more narrow (often MUCH more narrow) than the
light cone ... it's actual width will depend on the accelleration
characteristics of the target.)
John Rudd (yes, that's really my email address)
>
> William Clifford posts, in part:
>
> What you could use these for is to force the target to move into the
> region where the guided missiles are. Carry a *lot* of buckshot with
> you when you do this.
>
> I'm also not completely convinced of the effectiveness of ball bearing in the
> first place.
>
> The idea behind them is to pack enough kinetic energy into them that they
> essentially generate a small explosion when they hit the ship, which is enough
> to tear a sizable hole in the hull.
>
> That works - for the outer hull. But an inner hull a few feet deeper will be
> harder to affect, since the 'blast' from the initial impact attenuates rapidly,
> especially if the two hulls are separated by vacuum.
The distance between the outer hull and inner hull isn't likely to matter
too much for purposes of attenuation. What matters is how thick the cloud
is ... if it's a 1 particle thin wall that moves across the target, then
only the outer hull will get struck.. but if it's a cloud with actual
thickness, then you'll get continuous sandstorm-like impacts which will
erode the layers of hull as they hit, with more erosion happening for
thicker clouds (for thickness here, I'm not refering to density of the
cloud, but depth between teh leading and trailing edges of the cloud).
Also, vacuume is probably not the best insulator. Instead,
compartmentalize the inner-to-outer hull region, and fill it with light but
opaque gases. That way, when their compartments are breached, the gas will
vent out of the breach, either interfering with the laser that breached
them (hopefully dissipating the laser so it doesn't continue further in to
the hull), or the outward momentum of the gas will slow the incoming
pebbles... it's sort of a 'reactive armor' concept.
>
> Now, if the ball bearing are going at near light speed, rather than a mere
> 20,000 mph, a second hull may not help much. But how do you get them up to
> near light speed in the first place?
>
Depends on how big the balls are. Just how much kinetic energy does a
dense cloud of alpha particles moving at .75c have? It's not too hard to
impart a high velocity on to an alpha particle.. though, it does require a
lot of particle accellerators to create a cloud of them.
John Rudd (yes, that's really my email address)
>
> If you really want to go to war against some other race, you wouldn't
> do combat in space, you would just accelerate a mass to very high
> velocity and crash it into their home planet.
That works for xenophobic wars of genocide, or defending against a
colonizing invasion where you have no desire to colonize them. On the
other hand, if you're fighting a war of expansion, you don't want to turn
your future colony into a nuclear winter zone, or lifeless rock.
Instead, you'll probably throw platforms at them, where each platform has
MIRVs on it.. and you can target the MIRVs on targets of opportunity as
htey pass through their system. Drop the MIRVs on any ships or satalites
in orbit of their planet (when they're at the point of their orbit that
doesn't have the planet behind them, so that the MIRV's momentum takes it
past the planet instead of down onto the planet, after it hits the target),
any space stations, etc.
Once you clean their system of noticible space vehicles, you send your
planetary assault ships in to start the space marine phase of the battle.
You'll also need to keep around a few ships to clean up any of their space
ships you missed. (actually, you'll probably want to do a LOT of mopping
up and selective orbital bombardment of planet side space ports before you
move to the planetary assult phase ... you really don't want to worry about
a lone straggler taking out one of your main space marine transports).
Bob
Ok, excuse my ignorance of the actual physics of a nuke...
Isn't there some general "blast force" generated by a nuclear device? I
mean, besides the heat, radiation/ionization, and EMP pulse, doesn't the
nuke generate some kinetic energy, even in a vacuum? How big is the
actual fireball? Would there even be a fireball per se, in the absence of
an atmosphere?
What I am trying to get at is, that even in the vacuum of space, a large
enough of a nuke could cause some serious damage, as long as it was
relatively close (say within a couple thousand meters). Am I way off
course, here?
My second point, more importantly, is that I think you probably don't want
a ship-based combat system with too much realism, as the required math
would probably interfere with game enjoyment. Rather, you want a system
that simulates the realism, without getting buried in it. I don't really
know what a good compromise would be...
-Just a side note... Don't we already have the tech to generate and
contain *very* small quantities of antimatter? Three or four
anti-particles, at least? If we extrapolate out 50-100 years, I would
think that an anti-matter "bullet" (a few thousand anti-protons, in a
small containment system that ejects them on impact) would make an
excellent vacuum-based weapons system. I know that this smacks of Trek's
"photon torpedos", but it could happen! You might not even need a
containment system, but rather could use some kind of particle
(anti-particle) beam, although you might have to use some kind of laser
carrier to "pre-ionize" the anti-matter path...
But, then again, like I said before, I don't have the physics for all of
this!
Just my $.02!
-Bob
Estne rosa ab quis nomine iustus ut dulcis?
Bob McCann
rmc...@mesastate.edu
John Rudd (yes, that's really my email address)
>
> Ok, excuse my ignorance of the actual physics of a nuke...
>
> Isn't there some general "blast force" generated by a nuclear device? I
> mean, besides the heat, radiation/ionization, and EMP pulse, doesn't the
> nuke generate some kinetic energy, even in a vacuum? How big is the
> actual fireball? Would there even be a fireball per se, in the absence of
> an atmosphere?
>
> What I am trying to get at is, that even in the vacuum of space, a large
> enough of a nuke could cause some serious damage, as long as it was
> relatively close (say within a couple thousand meters). Am I way off
> course, here?
The 'shockwave' of a nuclear blast comes from a compression wave through
the air. No air, no shockwave. That's where the _kinetic_ part of the
nuclear explosion energy comes from. There's also a huge release of
electromagnetic radiation (in several parts of the spectrum, including
IR/heat, and the parts that bear the EMP, which I think are in the radio or
microwave range but I'm not sure), ionizing radiation, neutrons, and gamma
radiation.
I would suspect that the neutrons, if you could shape their explosion (and
there ARE ways to shape a nuclear explosion) would be the most useful part
of a nuclear space blast. So, you may want to concentrate on a neutron
bomb type device, with a shaped warhead ... so you're effectively building
a "one shot" missile that has a neutron particle beam instead of a high
energy laser.
>
> My second point, more importantly, is that I think you probably don't want
> a ship-based combat system with too much realism, as the required math
> would probably interfere with game enjoyment. Rather, you want a system
> that simulates the realism, without getting buried in it. I don't really
> know what a good compromise would be...
I agree.. you want an accurate but abstract model of the process, not a
detailed mathematical model of the process. But you also want to model it
at a level that makes it fun. That's 3 axes: accuracy, abstraction, fun.
It's not easy to optimize for 2 variables, much less 3.
>
> -Just a side note... Don't we already have the tech to generate and
> contain *very* small quantities of antimatter? Three or four
> anti-particles, at least? If we extrapolate out 50-100 years, I would
> think that an anti-matter "bullet" (a few thousand anti-protons, in a
> small containment system that ejects them on impact) would make an
> excellent vacuum-based weapons system. I know that this smacks of Trek's
> "photon torpedos", but it could happen! You might not even need a
> containment system, but rather could use some kind of particle
> (anti-particle) beam, although you might have to use some kind of laser
> carrier to "pre-ionize" the anti-matter path...
>
You're basically talking about an anti-matter particle beam (easier to
generate a stream of generic anti-matter particles than to try to form them
into a specific hunk of matter). Not unreasonable. Probably would require
a lot of energy, but then so would a 'photon torpedoe' or 'phaser'.
Scott Barrie
Davies) wrote:
>What you want is two (or more) heavy objects on the ends of long bits
>of elastic. Chuck them out of the ship so that the whole ensemble
>starts to oscillate chaotically (that's why you have 2 lumps - it's a
>3-body problem) around its centre of mass. You don't actually use any
>fuel to dodge except for the initial energy to get them moving. Alter
>the tension on the elastic now and again to confuse the enemy
>targeting system.
Cool! I'm using this in some form the next time I run a sci-fi game.
Sidhain
Scott Barrie <sba...@julian.uwo.ca> wrote in message
news:0qITOBEDDZ0ROJ...@4ax.com...
Aye in my Hard Sci Fi game we called em "wobblies":
Robin Lim
Colin Smith <co...@Yelm.freeserve.co.uk> wrote in message
news:slrn811pp...@Orlanth.homenetwork...
> On 21 Oct 1999 21:09:31 GMT, John P. Raynor <jra...@pantheon.yale.edu>
wrote:
> Not too sure, but I suspect that mass canon would be highly effective.
>
> Accelerate a few thousand steel ballbearings up to 20,000mph and watch
> them tear the target to pieces. Very difficult to counter.
At speeds like that, dumping a bucket of water out the back can be deadly.
c.f. Startide Rising, by David Brin.
My perverse mind envisions captains giving orders to "flush the organic
waste tanks!" Talk about crap bombs.
Rob
Henry Penninkilampi
j...@moose.powernet.co.uk.hat wrote:
> >Question: With speed-of-light weapons, how can you even *attempt* to
> >evade an attack that you have *NO WAY* of detecting before it actually
> >hits? You DON'T. That just leaves you with one option: To *continually*
> >engage in 'random' evasive maneuvers which effect the largest
> >displacements in your profile.
> >
> >Furthermore: All this maneuvering will chew up an *amazing* amount of fuel.
>
> What you want is two (or more) heavy objects on the ends of long bits
> of elastic. Chuck them out of the ship so that the whole ensemble
> starts to oscillate chaotically (that's why you have 2 lumps - it's a
> 3-body problem) around its centre of mass. You don't actually use any
> fuel to dodge except for the initial energy to get them moving. Alter
> the tension on the elastic now and again to confuse the enemy
> targeting system.
This sounds pretty cool for a non-hard-science campaign, but what about:
1) In order to create a 'stable' oscillation, all of the three bodies need
to have the same mass, correct? Unless the ship is going to carry around
2x it's own mass in dead weight, where is this extra mass going to come
from? No problems with station-based craft, but the rest will be cruising
space for long periods at a time and (more than) tripling their propulsion
requirements to carry this extra weight is not likely to happen.
2) If the masses are significantly smaller, then insufficient amounts of
energy will exist in the system to displace the ship enough to classify as
an 'effective' evasion.
3) If you increase the velocity of the smaller bodies to compensate, then
how significant are the risks of collision between the ship and one or
more of the other masses in the event that an explosion occurs nearby
(missile with proximity-charge-type-thing), with enough force to bumb one
of the massess off-course - just a little bit.
4) I imagine it is a quite delicate task to get a stable (non-colliding)
3-body system going. Unless I'm mistaken, wouldn't this imply that the
two masses must have thrusters (probably remotely controlled from the
ship) to fire intermittently to make vector adjustments? IIRC, the motion
of a single body in a 3-body system (ie. the ship) is insufficient in
order to keep the whole thing in balance.
5) Is it possible to create a stable, 'chaotic' 3-body system in only a
single plane? I've seen very predictable ones, but not very chaotic
ones. If not, then a lot of the motion of the bodies will occur in a
direction which is of little defensive benefit, correct? (Assuming
chaotic motion in the plane perpendicular to approach is the ideal.)
6) If the motion is truly chaotic (as it would need to be in order to make
the tactic effective) won't that make it very difficult for the
'oscillating' ship to engage in any effective weapons fire whatsover with
directed weapons? Effective directed fire requires a stable firing
platform, or at least a firing platform where you have precise control
over changes in velocity (which can be fed into the battle computer
*before* they happen in order to allow it to compensate).
7) Do all bodies in the system exhibit equally chaotic motion? If not,
couldn't the tactic be invalidated simply by firing upon the single body
that demostrated the least chaotic motion?
8) Point-defense systems are usually mounted on ships to protect them from
missiles. Putting aside the 'unstable firing platform' issue for the
moment, wouldn't this method of defense require the placement of
point-defense systems on the other two masses to protect them from
incoming missiles also?
9) Roughly how long would the elastic cables need to be? Would the length
(and size) of the cables be sufficient to make them detectable to
targetting and tracking systems, and thus make them an equally valid
target? I'm assuming that the nature of 'elastic' cables prohibits them
from being armoured, and makes then succeptible damage from radiation
and/or fragmentation (typical of a missile explosion nearby).
10) Won't the biological crew get really, really sick?
That's all I can think of from the top of my head.
It's a neat idea, and it's definitely going down on 'the list', but I have
serious doubts about it's vability in "Realistic" Spaceship Combat.
Henry.
James Nicoll
>the air. No air, no shockwave. That's where the _kinetic_ part of the
>nuclear explosion energy comes from. There's also a huge release of
>electromagnetic radiation (in several parts of the spectrum, including
>IR/heat, and the parts that bear the EMP, which I think are in the radio or
>microwave range but I'm not sure), ionizing radiation, neutrons, and gamma
>radiation.
In vacuum, the EM is mostly gamma rays. No air to step it down by
absorption and reemission, you see. It doesn't take much energy to kill
cells with hard radiation so the maximum theoretical kill zone is pretty
big, thousands of km for unprotected people and a 1 MT nuke. Shielding
isn't an absolute savior either: if the shielding cuts the dose by 10,000,
the inverse square law says you can make it up by detonating 100x as close.
One plan for deflecting asteroids is to detonate a nuke nearby
evaporating the surface and pushign the rock with the vaporised gasses.
I imagine that'd be annoying with spacecraft as well, since there is AFAIK
no such thing as a gamma ray mirror.
--
"You know, it's getting more and more like _Blade Runner_ down
here."
A customer commenting on downtown Kitchener
Henry Penninkilampi
>>>> One of the important points to remember is that huge warships would have
>>>> such a massive amount of momentum that they *can't* turn quickly. That
>>>> means that 'evasion' is *NOT* a really viable option.
It was not until Scott Barrie <sba...@julian.uwo.ca> wrote:
> Acceleration is the key to being unpredictable. Velocity and momentum
> have nothing to do with it.
...that I realised I had stuffed up. Scott is correct. Sorry I wasted
everyone's time. I should have written "huge warships would have such a
massive amount of *inertia* that they...". Momentum was the wrong word
and lead to a dubious line of reasoning.
Nonetheless... ;)
Everyone here probably knows that a = f / m and that more massive ships
use more fuel to accelerate. The relationship appears linear, which may
lead one to believe that a huge ship can be just as 'agile' as a small
ship - just add more fuel and bigger engines.
I don't think this is the case, however, and my logic follows the same
reasoning that insects only get so big: Structural strength (ability to
withstand the stresses of acceleration (ie. evasion)) is based on
cross-sectional area and increases according to the squared rule. Volume
(as a result of an increase in mass) increases according to the cubed
rule. Thus a larger (more massive) ship requires a *disproportionately*
larger amount of mass devoted to structural integrity. This means there
are diminishing returns to be gained by making larger and larger ships
equally as agile as smaller ships. Diminishing returns mean that larger,
agile warships carry less and less weapons.
Now, unless I've stuffed up again, this is a *valid* reason why huge
warships can't be as evasive as small warships, and why a massive and
nimble ship would be little more than a (very strong) floating fuel-tank.
Anyone care to comment?
Henry.
Scott Barrie
Penninkilampi) wrote:
>In article <38122c6d...@news.powernet.co.uk>,
>j...@moose.powernet.co.uk.hat wrote:
>> What you want is two (or more) heavy objects on the ends of long bits
>> of elastic. Chuck them out of the ship so that the whole ensemble
>> starts to oscillate chaotically (that's why you have 2 lumps - it's a
>> 3-body problem) around its centre of mass. You don't actually use any
>> fuel to dodge except for the initial energy to get them moving. Alter
>> the tension on the elastic now and again to confuse the enemy
>> targeting system.
>
>This sounds pretty cool for a non-hard-science campaign, but what about:
I'll comment on what I can, and skip what I can't.
>1) In order to create a 'stable' oscillation, all of the three bodies need
>to have the same mass, correct? Unless the ship is going to carry around
>2x it's own mass in dead weight, where is this extra mass going to come
>from? No problems with station-based craft, but the rest will be cruising
>space for long periods at a time and (more than) tripling their propulsion
>requirements to carry this extra weight is not likely to happen.
I don't believe they have to be exactly the same mass. I'd put guns
and whatnot in each portion. Why waste the mass?
>2) If the masses are significantly smaller, then insufficient amounts of
>energy will exist in the system to displace the ship enough to classify as
>an 'effective' evasion.
True. You'd want you vital systems in the smallest section.
>3) If you increase the velocity of the smaller bodies to compensate, then
>how significant are the risks of collision between the ship and one or
>more of the other masses in the event that an explosion occurs nearby
>(missile with proximity-charge-type-thing), with enough force to bumb one
>of the massess off-course - just a little bit.
Hmmmm... if one of the end masses gets knocked towards the center,
then the central mass is only going be pulled by the far mass,
essentially pulling the center out of the way?
In other words, I don't know. Can someone who's studied the problem
answer this?
>4) I imagine it is a quite delicate task to get a stable (non-colliding)
>3-body system going. Unless I'm mistaken, wouldn't this imply that the
>two masses must have thrusters (probably remotely controlled from the
>ship) to fire intermittently to make vector adjustments? IIRC, the motion
>of a single body in a 3-body system (ie. the ship) is insufficient in
>order to keep the whole thing in balance.
No, you could make a pretty self regulating system.
>5) Is it possible to create a stable, 'chaotic' 3-body system in only a
>single plane? I've seen very predictable ones, but not very chaotic
>ones. If not, then a lot of the motion of the bodies will occur in a
>direction which is of little defensive benefit, correct? (Assuming
>chaotic motion in the plane perpendicular to approach is the ideal.)
True, I suspect.
>6) If the motion is truly chaotic (as it would need to be in order to make
>the tactic effective) won't that make it very difficult for the
>'oscillating' ship to engage in any effective weapons fire whatsover with
>directed weapons? Effective directed fire requires a stable firing
>platform, or at least a firing platform where you have precise control
>over changes in velocity (which can be fed into the battle computer
>*before* they happen in order to allow it to compensate).
Well, the computer only needs to know it's current velocity. It should
be fast enough to be effective with just this. Second, since you know
the current tension in the elastic, so you can predict your own motion
for at least a short period into the future.
>8) Point-defense systems are usually mounted on ships to protect them from
>missiles. Putting aside the 'unstable firing platform' issue for the
>moment, wouldn't this method of defense require the placement of
>point-defense systems on the other two masses to protect them from
>incoming missiles also?
Yep, unless the whole ensemble could be covered in the range of a
single point defense system.
>9) Roughly how long would the elastic cables need to be? Would the length
>(and size) of the cables be sufficient to make them detectable to
>targetting and tracking systems, and thus make them an equally valid
>target? I'm assuming that the nature of 'elastic' cables prohibits them
>from being armoured, and makes then succeptible damage from radiation
>and/or fragmentation (typical of a missile explosion nearby).
Beats me. I think a couple of hundred meters would be cool. The cables
would move as unpredictably as the rest, and they'd have a pretty
small cross section, so while cutting the cord would be possible, I
don't think it would be trivial.
>10) Won't the biological crew get really, really sick?
Oh, hell yeah. Place your recruitment stations near roller coasters.
You'd have to work out the system's maximum acceleration too, so you
don't kill the crew.
Again, any comments from someone who's studied the system?
simonh...@my-deja.com
This hardly sounds like it will make a stable platform for a
weapons system or sensors. How do you manoeuver this mess? How
do you engineer your attitude controll systems for orientation,
tracking and target acquisition?
> >2) If the masses are significantly smaller, then insufficient
amounts of
> >energy will exist in the system to displace the ship enough to
classify as
> >an 'effective' evasion.
>
> True. You'd want you vital systems in the smallest section.
How do you mprevent collisions between the elements of the system?
> >3) If you increase the velocity of the smaller bodies to compensate,
then
> >how significant are the risks of collision between the ship and one
or
> >more of the other masses in the event that an explosion occurs nearby
> >(missile with proximity-charge-type-thing), with enough force to
bumb one
> >of the massess off-course - just a little bit.
>
> Hmmmm... if one of the end masses gets knocked towards the center,
> then the central mass is only going be pulled by the far mass,
> essentially pulling the center out of the way?
How big a mass are vwe talking about here. What are the tensile
strengths and elasticities of the elastic elements? Compare and contrast
with the forces exterted by tactical nuclear ordinances.
> In other words, I don't know. Can someone who's studied the problem
> answer this?
>
> >4) I imagine it is a quite delicate task to get a stable (non-
colliding)
> >3-body system going. Unless I'm mistaken, wouldn't this imply that
the
> >two masses must have thrusters (probably remotely controlled from the
> >ship) to fire intermittently to make vector adjustments? IIRC, the
motion
> >of a single body in a 3-body system (ie. the ship) is insufficient in
> >order to keep the whole thing in balance.
>
> No, you could make a pretty self regulating system.
Which would make it behave within predictable limits. How near a miss
can the craft survive? Will the parts of the ship be moving fast enough
on their elastic tethers to evade self-guided munitions?
> >5) Is it possible to create a stable, 'chaotic' 3-body system in
only a
> >single plane? I've seen very predictable ones, but not very chaotic
> >ones. If not, then a lot of the motion of the bodies will occur in a
> >direction which is of little defensive benefit, correct? (Assuming
> >chaotic motion in the plane perpendicular to approach is the ideal.)
>
> True, I suspect.
>
> >6) If the motion is truly chaotic (as it would need to be in order
to make
> >the tactic effective) won't that make it very difficult for the
> >'oscillating' ship to engage in any effective weapons fire whatsover
with
> >directed weapons? Effective directed fire requires a stable firing
> >platform, or at least a firing platform where you have precise
control
> >over changes in velocity (which can be fed into the battle computer
> >*before* they happen in order to allow it to compensate).
>
> Well, the computer only needs to know it's current velocity. It should
> be fast enough to be effective with just this. Second, since you know
> the current tension in the elastic, so you can predict your own motion
> for at least a short period into the future.
Thats assuming that physical orientation of the weapon itself isn't
required, only accurate targeting data, from randomly moving sensors.
Bad idea.
> >8) Point-defense systems are usually mounted on ships to protect
them from
> >missiles. Putting aside the 'unstable firing platform' issue for the
> >moment, wouldn't this method of defense require the placement of
> >point-defense systems on the other two masses to protect them from
> >incoming missiles also?
>
> Yep, unless the whole ensemble could be covered in the range of a
> single point defense system.
>
> >9) Roughly how long would the elastic cables need to be? Would the
length
> >(and size) of the cables be sufficient to make them detectable to
> >targetting and tracking systems, and thus make them an equally valid
> >target? I'm assuming that the nature of 'elastic' cables prohibits
them
> >from being armoured, and makes then succeptible damage from radiation
> >and/or fragmentation (typical of a missile explosion nearby).
What happens if the elastic cables are snapped by a hit, or near miss?
Also, these masses would have to have their own power, propulsion
systems, armjour, weapons, targeting systems, etc, etc. Effectively
they're seperate ships. Personaly I doubt you could set up man elastic
system capable of significantly manoeuvering several masses in the order
of a hundred tons or more, but even if you could, you'd be better off
manoeuvering the sections away from each other, reducing the chances
of a one-shot kill from a proximity weapon on the lot, or secondary
damage and loss of controll of two of the sections due to a hit on
one of the others.
Utterly impractical.
Simon Hibbs
Sent via Deja.com http://www.deja.com/
Before you buy.
Timothy J. Miller
> Wouldn't the surface of the ship and the air inside it provide enough stuff
> to ionise?
EMP requires ions moving in a magnetic field. Planet-side,
the magnetosphere provides the field and the air provides the ions.
In deep interplanetary space, the device can provide the ions but
you're lacking a field. I lack the physics to calculate the EMP from
a one-megaton burst in the solar magnetosphere at 1 AU. Anyone? Or
should we segue over to r.a.sf.science?
Timothy J. Miller
> A kinetic kill does require contact, doesn't it? The nuclear warhead
> would provide more enrgy than an equivalent mass of chemical rocket fuel.
A 1 megaton nuclear blast is equivalent to a 1 kg object
moving at 64K km/s, or roughly .2 c. How heavy was your warhead
again?
But this is an oversimplification; the nuke won't deliver its
total potential on-target per our previous assumptions. So let's
assume a surface detonation (the nuke goes off immediately prior to
actual impact)-- about 50% of the energy is then deposited on-target
(assuming the ship is large in comparison to the blast radius, another
simplification but hey, that's what physics is). In this case, my 1
kg projectile need only be going ~.15 c to be equivalent.
Now we'll look at a realistic proximity detonation, where 25%
of the blast energy is deposited on-target; now my slug need only be
travelling .1 c to remain equivalent.
Now, while a nuke need only be nearby and a slug has to
impact, I can throw FAR FAR MORE slugs than you can throw nukes...
Tim
>I (td...@netcom.com) wrote:
>>I'd say they'd be fairly sterile and passionless.
>>Think the bland passages recounting starship combat in "The Forever War".
>A few years ago there was a computer game "Mantis" which featured realistic
>space combat . . . and it was incredibly dull.
Never said it wouldn't be. Just said it would be realistic. On a tangent,
thinking hacking vs. cyberfiction computer intrusion. Most of the hacking
I've heard of isn't a reflex-based challenge, it's probing for weakness
(boring and dreary), writing something to exploit that weakness (more
tedium, especially if you test your software instead of just slapping it
together) and then waiting for the opportunity to use it. OTOH, cy-fi
comptuer intrusion is portrayed to be more hands-on, more here-n-now.
tim
Doug Berry
Elvis who passed this on:
>Never said it wouldn't be. Just said it would be realistic. On a tangent,
>thinking hacking vs. cyberfiction computer intrusion. Most of the hacking
>I've heard of isn't a reflex-based challenge, it's probing for weakness
>(boring and dreary), writing something to exploit that weakness (more
>tedium, especially if you test your software instead of just slapping it
>together) and then waiting for the opportunity to use it. OTOH, cy-fi
>comptuer intrusion is portrayed to be more hands-on, more here-n-now.
Read "Takedown" by Tsutomu Shimomura and John Markoff for a good
example or real life computer hacking.
Tsutoma often takes extended weekends and long drives while
pursuing Mitnick, for the simple reason there's nothing he could
do until the computers finish a run, or Mitnick struck again.
This is why I've always kept the hacker types as NPCs. Slightly
crazed, permanently on-line otaku whose motives you're never
quite sure of.. they *like* screening thousands of email headers
for the IP address you're looking for...
--
Douglas E. Berry grid...@mindspring.com
http://gridlore.home.mindspring.com/
"We are GURPS. You will be assimilated. We will add
your distinctive setting and background to our own. |
Resistance is futile."
Eric Stevenson
: Luke Campbell wrote in message <381261B6...@u.washington.edu>...
: >The EMP effect is caused by gamma rays from the blast knocking electrons
: off air molecules. The free electrons gyrate around the earth's
: Wouldn't the surface of the ship and the air inside it provide enough stuff
: to ionise?
If you're ionizing the enemy ship, I don't think you need to worry about
the EMP.
Eric Stevenson
: Eric Stevenson <es...@umr.edu> writes:
: > A kinetic kill does require contact, doesn't it? The nuclear warhead
: > would provide more enrgy than an equivalent mass of chemical rocket fuel.
: Now we'll look at a realistic proximity detonation, where 25%
: of the blast energy is deposited on-target; now my slug need only be
: travelling .1 c to remain equivalent.
'Only?' What are you using to propel the slug to 0.1 c?
: Now, while a nuke need only be nearby and a slug has to
: impact, I can throw FAR FAR MORE slugs than you can throw nukes...
Okay, you win. Your ship is obviously much bigger than mine, since it
carries FAR FAR MORE stored energy, in chemical form, as opposed to my
compact nuclear weapons. Naturally, your battleship will defeat my
corvette.
I was simply commenting on the statement that replacing a nuclear warhead
with rocket fuel was a good idea. Nuclear devices massing less than 100
kg can have a yield of kilotons, making them far more efficient than
chemicals.
As far as actual combat utility goes, I don't know enough to state
whether many small slugs or a few nuclear missiles would be superior.
I'd guess that the slugs would be better at close range, while
the nukes would be better at long range. Slugs are cheaper, but at longer
ranges, it gets harder to hit, since you don't know where the target will
be when the slugs get there. The more guidance you put on the slugs, the
fewer of them you can send. At some point, you might as well put a
warhead on them.
Eric Tolle
(delete)
> Now we'll look at a realistic proximity detonation, where 25%
> of the blast energy is deposited on-target; now my slug need only be
> travelling .1 c to remain equivalent.
>
> Now, while a nuke need only be nearby and a slug has to
> impact, I can throw FAR FAR MORE slugs than you can throw nukes...
Show me the accelerator that can accelerate 1 kilogram slugs to
.1 c and I'll buy that slugs are more efficient a weapon system.
The real problem with using HV slugs to deliver equivalent energy
levels is that anything the slug does has to be done to it first-
IE the launcher has to deliver energies in the range of a megaton
nuclear device. This is not a trivial problem-in fact it has a host
of problems that make it an unlikely weapon without massive infusions
of" magic" tech.
For any fairly realistic space combat scenario, a nuclear tipped
missile is going to be more effective then a relativistic slug
launcher. And this is leaving aside the fact that a relativistic
slug _still_ has to hit. As a contrast, the figures I've seen in
rasf.science for the kill range of a 1-megaton nuke in space are in
the tens to the hundreds of kilometers.
--
Eric Tolle sch...@silcom.com
Information does not want to be free. Information wants to be
folded, spindled, mutilated, and used to make funky children's
party hats.
Eric Stevenson
: anything near "instantaneous information" unless you're at a trivially
: short distance (which, for modern warfare, you pretty much are at trivially
: short distances, for comparison to sub-light space warfare). You have to
: start thinking much more in the "wall of lead" mindest, because it's
: prohibitively difficult to try to build weapons under the "precision
: munitions" mindset.
I'd think that at longer ranges, you need to get back into single shot
systems (in the form of guided weapons), since the light cone just gets way
too big to fill. Or maybe not, if the defenders can bring down these
weapons too easily.
: The problem becomes one of having plentiful, cheap, but lethal weapons
: (pebbles that move fast enough to be devastating to anything they hit, yet
: that have a lifetime so that they don't injure unintended targets if they
: miss the primary target
An interesting idea. I would have thought that space is too big to worry
about where high velocity pebbles will go, especially if they have solar
escape velocity. Adding in fuzes to destroy them makes them more
expensive and only increases the number of pebbles. I guess the
projectiles could be made of some material that vaporizes in the sun's
light, but these materials will be harder to store and fire.
Eric Tolle
>
> Come to think of it...are there *any* good reasons to use energy weapons?
> The inverse-square law is such a huge disadvantage. I can see using
The inverse-square law really doesn't directly apply to lasers.
Lasers do undergo diffusion of the beam, but the angle of the
diffusion (and hence the effective range) is based on the wavelength
and the size of the focusing lens.
Give me a high-frequency laser and the right sized focusing system,
(and the power as well) and I could have a pretty decent weapons
system for any range you specify. Of course after a certain point
the size of the system gets to be rather impractical.
Wasn't it "Holy War" that had lasers with planet-sized lenses?
Eric Stevenson
: 6) If the motion is truly chaotic (as it would need to be in order to make
: the tactic effective) won't that make it very difficult for the
: 'oscillating' ship to engage in any effective weapons fire whatsover with
: directed weapons? Effective directed fire requires a stable firing
: platform, or at least a firing platform where you have precise control
: over changes in velocity (which can be fed into the battle computer
: *before* they happen in order to allow it to compensate).
Seems likely. Guided weapons would probably be required.
: 7) Do all bodies in the system exhibit equally chaotic motion? If not,
: couldn't the tactic be invalidated simply by firing upon the single body
: that demostrated the least chaotic motion?
I would think that the point of the system is to make the bodies hard to
hit because they are unpredictable, not simply put a couple of decoys out.
The system would have to be fairly large, since if the bodies are close
together, they can simply be shotgunned. Rapid motion is not necessary in
this case, just unpredictable motion. The various bodies are on a few
miles of wire, moving around randomly in a volume of a few cubic miles.
It might be effective against long range attacks by unguided weapons and
beams.
Maybe you don't even have to set up the oscillations. Just kick out a
mass or two on cables and randomly jerk the cables to change your
velocity. If you survive the fight, you can reel in your reaction mass,
an advantage over rockets.
Eric Stevenson
: Isn't there some general "blast force" generated by a nuclear device? I
: mean, besides the heat, radiation/ionization, and EMP pulse, doesn't the
: nuke generate some kinetic energy, even in a vacuum? How big is the
: actual fireball? Would there even be a fireball per se, in the absence of
: an atmosphere?
Sure. The weapon itself will become a cloud of plasma. It has pretty much
an unlimited radius, since there's nothing to stop it expanding. Its
effectiveness will drop as it gets bigger, though. I'd think the damage
from the gamma rays and neutrons from the weapon would represent the
lion's share of the damage.
: What I am trying to get at is, that even in the vacuum of space, a large
: enough of a nuke could cause some serious damage, as long as it was
: relatively close (say within a couple thousand meters). Am I way off
: course, here?
That sounds reasonable, depending on the size of the nuke.
: -Just a side note... Don't we already have the tech to generate and
: contain *very* small quantities of antimatter? Three or four
: anti-particles, at least?
That's more or less in the neighborhood. A few particles.
If we extrapolate out 50-100 years, I would
: think that an anti-matter "bullet" (a few thousand anti-protons, in a
: small containment system that ejects them on impact) would make an
: excellent vacuum-based weapons system.
Depends. Antimatter gives you the most energy per gram, so it's a great
for spaceships, which need to save on weight. It would be better than
anything else in a warhead, or as a pellet or particle beam.
It's great stuff, *if* you can get it. Currently, you'd be better off
just throwing the energy at the guy in the first place, instead of
wasting 99.9etc percent of it making antiprotons in a particle
accelerator. Whatever kind of power plant you have powering your
particle accelerator, it would be better to make bombs with the reactor
fuel.
Eric Stevenson
: In vacuum, the EM is mostly gamma rays. No air to step it down by
: absorption and reemission, you see. It doesn't take much energy to kill
: cells with hard radiation so the maximum theoretical kill zone is pretty
: big, thousands of km for unprotected people and a 1 MT nuke. Shielding
: isn't an absolute savior either: if the shielding cuts the dose by 10,000,
: the inverse square law says you can make it up by detonating 100x as close.
Getting that much shielding is going to be pretty heavy, too. I seem to
recall that a tenth thickness of lead is about half a centimeter for
gamma rays (varies with energy, of course, but hey, it's in the
ballpark). So to cut the dose by 10,000 takes a couple centimeters of
lead. Not so bad, until you consider how many square centimeters you'll
need to cover your ship. Of course, if you've got the engine power and
fuel to tote around some armor, radiation won't be a big worry.
Bertil Jonell
>Getting that much shielding is going to be pretty heavy, too. I seem to
>recall that a tenth thickness of lead is about half a centimeter for
>gamma rays (varies with energy, of course, but hey, it's in the
>ballpark).
You'll need pretty heavy shielding to survive long periods in the
inner system (solar flares) or to go anywhere around gas giants.
-bertil-
--
"It can be shown that for any nutty theory, beyond-the-fringe political view or
strange religion there exists a proponent on the Net. The proof is left as an
exercise for your kill-file."
Bertil Jonell
>just throwing the energy at the guy in the first place, instead of
>wasting 99.9etc percent of it making antiprotons in a particle
>accelerator. Whatever kind of power plant you have powering your
>particle accelerator, it would be better to make bombs with the reactor
>fuel.
But you don't have to make the anti-matter in the ship. You can
make it using fusion power on a planet, or using solar power in orbit
(possibly close to the sun) (Cf. Hamiltons 'The Naked God', or Vinges
'Marooned in Realtime') and transport it to where it is needed.
Antimatter isn't an energy *source*, its an extremely energy-dense
*battery*.
Luke Campbell
> John P. Raynor wrote:
> >
> > Come to think of it...are there *any* good reasons to use energy weapons?
> > The inverse-square law is such a huge disadvantage. I can see using
>
> The inverse-square law really doesn't directly apply to lasers.
> Lasers do undergo diffusion of the beam, but the angle of the
> diffusion (and hence the effective range) is based on the wavelength
> and the size of the focusing lens.
Well, if I am twice as far away, the diffraction limited spot that your laser
can focus on my ship will be twice as wide. It will thus have four times the
area, and one quarter the energy density. This is still an inverse square
law.
> Give me a high-frequency laser and the right sized focusing system,
> (and the power as well) and I could have a pretty decent weapons
> system for any range you specify. Of course after a certain point
> the size of the system gets to be rather impractical.
This is true, especialy if you start using synthetic apertures or phased
arrays (several widely dispersed focal arrays that emit their radiation in
phase with each other. This gives an effective aperture of the approximate
diameter of the separation between the elements in your synthetic aperture.
Extending the phase linked focal arrays for an x-ray laser out on 100 meter
booms will give you useable ranges.
On the other hand, keep in mind it will be next to impossible to focus light
with an energy per photon much higher than the K absorption edge in plutonium
(and even this will require having a mirror made out of plutonium). This
essentially limits long range lasers to energies near or below 120 KeV.
One could always use particle beams - the relative wavelength here is the
de-broglie wavelength, which (for most particle beam weapons envisioned, on
the order of a GeV or more) will be quite a bit smaller than x rays, and thus
longer range. The problem with particle beams is that charged particles will
repel each other, so the beam will blow itself apart long before it gets near
the target. To correct for this, you need to use a beam of neutral atoms.
Since you cannot accelerate neutral atoms, you need to accelerate ions (or
individual protons) and then neutralize the beam by sending it through a foil
or gas filled chamber so some of the ions recombine with electrons. This,
unfortunately, heats the beam so that it has a wider focus than the
aforementioned x ray lasers. It might be possible to use laser cooling
methods to cool and focus the gas before it exits the weapon, but this will
take powerful lasers to accomplish much in the short time that these
relativistic ions will be in the weapon. It will probably also be very
difficult to design a synthetic aperture system for a particle beam.
Luke
Luke Campbell
> 1) In order to create a 'stable' oscillation, all of the three bodies need
> to have the same mass, correct? Unless the ship is going to carry around
> 2x it's own mass in dead weight, where is this extra mass going to come
> from? No problems with station-based craft, but the rest will be cruising
> space for long periods at a time and (more than) tripling their propulsion
> requirements to carry this extra weight is not likely to happen.
First, they only need comperable masses, not the same mass.
Second, this allows us to solve two problems at once. The long term comfort and
health of the crew requires artificial gravity, which will probably be provided
with a spin habitat. A simple, low mass spin habitat is to put the crew module
and life support out on one end of a tether, a couterweight (perhaps the power
generator, landing craft, weapons, etc) out on the other end of the tether, and
the drives and reaction mass (or at least enough reaction mass to survive the
battle, unless your elastic cables are also fuel pipelines) at the center of
gravity of the other two. When not in combat, spin the crew habitat and the
couterweight to generate gravity. When in combat, move the drive section off the
center of gravity, connect the crew section and the couterweight with a third
elastic cable, and set the whole thing jiggling.
Luke
Luke Campbell
> Getting that much shielding is going to be pretty heavy, too. I seem to
> recall that a tenth thickness of lead is about half a centimeter for
> gamma rays (varies with energy, of course, but hey, it's in the
> ballpark). So to cut the dose by 10,000 takes a couple centimeters of
> lead. Not so bad, until you consider how many square centimeters you'll
> need to cover your ship. Of course, if you've got the engine power and
> fuel to tote around some armor, radiation won't be a big worry.
I just calculated this, actually. About one and a quarter centimeters of lead
will cut the intensity of gamma rays by a factor of 1/2.71828... (ie, e^-1). Go
tohttp://physics.nist.gov/PhysRefData/XrayMassCoef/cover.html
for details about x ray mass attenuation coefficients in amny different
materials.
Luke
Luke Campbell
> -Just a side note... Don't we already have the tech to generate and
> contain *very* small quantities of antimatter? Three or four
> anti-particles, at least? If we extrapolate out 50-100 years, I would
> think that an anti-matter "bullet" (a few thousand anti-protons, in a
> small containment system that ejects them on impact) would make an
> excellent vacuum-based weapons system. I know that this smacks of Trek's
> "photon torpedos", but it could happen! You might not even need a
> containment system, but rather could use some kind of particle
> (anti-particle) beam, although you might have to use some kind of laser
> carrier to "pre-ionize" the anti-matter path...
If you want a particle beam, and you want relativistic particles so that your
beam travels at close to the speed of light, there will be as much or more
(probably lots more) energy in the kinetic energy of the beam than in the
rest mass of the particles. This means that the energy generated by the
collision of the particles (whether matter or antimatter) with the ship will
be about as much or more (probably lots more) than the energy liberated by
the annihilations of the antiparticles. To get highly penetrating radiation
effects and highly focusable beams, you want the energy per particle to be as
high as possible, which means that the difference between matter and
antimatter beams will be negligible, except that with antimatter beams, you
have to store or generate the antimatter to use.
As far as warheads go, though, antimatter cannot be beat. A 1 gram
antimatter pellet will pack the punch of a 20 kiloton or so nuke.
Luke
Luke Campbell
> Depends on how big the balls are. Just how much kinetic energy does a
> dense cloud of alpha particles moving at .75c have? It's not too hard to
> impart a high velocity on to an alpha particle.. though, it does require a
> lot of particle accellerators to create a cloud of them.
Alpha particles, being all positively charged, will repel each other. The cloud
would blow itself to bits long before it ever got to the target.
Luke
Jim Walters
: 'tis true, but badly stated. It is not that you increase your velocity,
: but that you accelerate. This acceleration, or DeltaV [DeltaV vs
: acceleration, because the time it takes you to change the velocity is
: irrelevant] cause you to go into a higher orbit.
I'm sorry, but I think my statement was far clearer than this.
You aren't changing your velocity, you are doing an acceleration which is
a delta v (delta v stands for a change in velocity), because the time you
take to change your velocity is irrelevant? Even if I ignore the sloppy
use of units, this all boils down to "you are changing your velocity".
--
Jim Walters jwal...@clark.net
"My race is pacifist and does not believe in war.
We kill only out of personal spite." Brain Guy - MST3K
John Rudd (yes, that's really my email address)
>
> John Rudd (yes, that's really my email address) <us...@domain.org> wrote:
> : In Space, the problem goes to huge extremes because it's impossible to get
> : anything near "instantaneous information" unless you're at a trivially
> : short distance (which, for modern warfare, you pretty much are at trivially
> : short distances, for comparison to sub-light space warfare). You have to
> : start thinking much more in the "wall of lead" mindest, because it's
> : prohibitively difficult to try to build weapons under the "precision
> : munitions" mindset.
>
> I'd think that at longer ranges, you need to get back into single shot
> systems (in the form of guided weapons), since the light cone just gets way
> too big to fill. Or maybe not, if the defenders can bring down these
> weapons too easily.
Depends. It especially depends on the type of guided weapon. A guided
weapon that is just a one-shot weapon, like a missle with a laser or
buckshot warhead, is just a way to reduce the range between your cannon and
target. But your cannon is still disposible, so you have to consider how
precise you want that cannon to be... the more accurage vs saturating it
is, the more expensive it will be.
If you fly a volley of buckshot missles at a target, they may be able to
get close enough to lower the light cone to a small enough envelope that
you can fill it with the buckshot from a few missiles.
>
> : The problem becomes one of having plentiful, cheap, but lethal weapons
> : (pebbles that move fast enough to be devastating to anything they hit, yet
> : that have a lifetime so that they don't injure unintended targets if they
> : miss the primary target
>
> An interesting idea. I would have thought that space is too big to worry
> about where high velocity pebbles will go, especially if they have solar
> escape velocity. Adding in fuzes to destroy them makes them more
> expensive and only increases the number of pebbles. I guess the
> projectiles could be made of some material that vaporizes in the sun's
> light, but these materials will be harder to store and fire.
Yes and no. Space is big, so if you're in deep space, you get a smaller
and smaller probability that the stray buckshot or laser beam will hit
anything of consequence, but it is still non-zero. To quote the nautical
rules "Any time two ships leave port anywhere in teh world, while the other
is still out on the seas, there is a non-zero chance they will collide"
.... it's better to be safe than sorry that a pebble you fire today wont
rip apart your grandson's hyperdrive.
And if the pebble is big enough, you don't want the pebble you fire today
to wipe out civilization on a small continent on the colony your
great-great-great grandson is convelesing on.
Start throwing away chunks of matter in space, and eventually they may very
well run in to something ... or, something may run in to them, if you're in
a major space-shipping lane at the time, or close to a star system (or,
worse yet, in a star system). The probability may be vanishingly small at
first, but it'll be out there _for_ever_. That's a lot of time to build up
your poisson distribution of the time between events, no matter how low the
probability of the individual event is.
--
John "kzin" Rudd kz...@domain.org http://www.domain.org/users/kzin
Truth decays into beauty, while beauty soon becomes merely charm. Charm
ends up as strangeness, and even that doesn't last. (Physics of Quarks)
-----===== Kein Mitleid Fu:r MicroSoft (www.kmfms.com) ======-----
Jim Davies
>Getting that much shielding is going to be pretty heavy, too. I seem to
>recall that a tenth thickness of lead is about half a centimeter for
>gamma rays (varies with energy, of course, but hey, it's in the
>ballpark). So to cut the dose by 10,000 takes a couple centimeters of
>lead. Not so bad, until you consider how many square centimeters you'll
>need to cover your ship. Of course, if you've got the engine power and
>fuel to tote around some armor, radiation won't be a big worry.
But you don't need to cover the whole ship, just the crew quarters
(and only those that need to be manned in combat) and any electronics.
The fuel tanks (a huge part of the ship) won't suffer much from a bit
of gamma.
Jim Davies
------------------------------------------
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Frank T. Sronce
>
> Start throwing away chunks of matter in space, and eventually they may very
> well run in to something ... or, something may run in to them, if you're in
> a major space-shipping lane at the time, or close to a star system (or,
> worse yet, in a star system). The probability may be vanishingly small at
> first, but it'll be out there _for_ever_. That's a lot of time to build up
> your poisson distribution of the time between events, no matter how low the
> probability of the individual event is.
>
> --
> John "kzin" Rudd kz...@domain.org http://www.domain.org/users/kzin
Yeah, there was a cute sci-fi novel about a future where Littering in
Space was a capital crime, because the scattered, unrecorded junk from
previous generations of space travellers had killed a lot of people.
They even had a special police force of sorts whose job was to
investigate possible space-dumpings and track down exactly what the
material was and where it was heading so that it could be dealt with, or
at least logged in the computers as a _known_ hazard.
Kiz
Eric Stevenson
: Eric Stevenson wrote:
: > An interesting idea. I would have thought that space is too big to worry
: > about where high velocity pebbles will go, especially if they have solar
: > escape velocity. Adding in fuzes to destroy them makes them more
: Start throwing away chunks of matter in space, and eventually they may very
: well run in to something ... or, something may run in to them, if you're in
: a major space-shipping lane at the time, or close to a star system (or,
: worse yet, in a star system). The probability may be vanishingly small at
: first, but it'll be out there _for_ever_. That's a lot of time to build up
Yeah, but space is 'full' of high velocity pebbles already. I don't think
a few space wars are going to affect this much. Besides, how far sighted
are today's militaries? We already see that they are pretty careless with
mines, and for that matter bombs.
Eric Stevenson
: But you don't have to make the anti-matter in the ship. You can
: (possibly close to the sun) (Cf. Hamiltons 'The Naked God', or Vinges
: 'Marooned in Realtime') and transport it to where it is needed.
: Antimatter isn't an energy *source*, its an extremely energy-dense
: *battery*.
Of course, but there is going to be some limit on how inefficient the
conversion of energy into antimatter is before it becomes wasteful to
make it. Currently, it takes huge amounts of energy to make trivial
amounts of antimatter, so we don't bother using antimatter to power
spacecraft, or anything else. The savings in weight on the spacecraft
would not be worth the cost of the fuel.
John P. Raynor
Distribution:
Eric Tolle (sch...@silcom.com) wrote:
: Show me the accelerator that can accelerate 1 kilogram slugs to
: .1 c and I'll buy that slugs are more efficient a weapon system.
Isn't there another problem with hurling slugs at 0.1c?
Recoil. If a slug is fired in one direction, the spaceship which
fires it will go in the other direction (a rocket engine could,
after all, be regarded as a way of firing countless tiny fast-moving
slugs). Here's a physics problem: if a spaceship with a mass of
10,000,000 kilograms fires a 1 kilogram slug "north" at 0.1c, how
fast will the ship be going "south?"
- J. Raynor
John Kim
John P. Raynor <jra...@pantheon.yale.edu> wrote:
>Isn't there another problem with hurling slugs at 0.1c?
>Recoil. If a slug is fired in one direction, the spaceship which
>fires it will go in the other direction (a rocket engine could,
>after all, be regarded as a way of firing countless tiny fast-moving
>slugs). Here's a physics problem: if a spaceship with a mass of
>10,000,000 kilograms fires a 1 kilogram slug "north" at 0.1c, how
>fast will the ship be going "south?"
The answer is 0.1c * (1 / 10,000,000) = 3 meters/second
This is just simple Newtonian conservation of momentum.
At 0.1c, the relativistic effects are negligible (a 0.5%
correction).
A potentially more significant problem, though, is that this
jump to 3 m/s occurs over a very short time span. Let's assume that
the slug is accelerated over 200 meters (the length of the ship).
Assuming constant acceleration, the slug is shot out in (10^-10)
seconds. This means that the ship undergoes a "jerk" of
3*10^9 gees to get to its 3 m/s recoil velocity.
S Cordner
> > Wouldn't the surface of the ship and the air inside it provide enough stuff
> > to ionise?
> EMP requires ions moving in a magnetic field. Planet-side,
> the magnetosphere provides the field and the air provides the ions.
> In deep interplanetary space, the device can provide the ions but
> you're lacking a field. I lack the physics to calculate the EMP from
> a one-megaton burst in the solar magnetosphere at 1 AU. Anyone? Or
> should we segue over to r.a.sf.science?
S Cordner
> with an energy per photon much higher than the K absorption edge in plutonium
> (and even this will require having a mirror made out of plutonium). This
> essentially limits long range lasers to energies near or below 120 KeV.
Couldn't you design a large fresnel lens capable of focusing an
essentially unlimited amount of energy into a single area of effect?