Realictic space battles / ships
max
As I said earlier, I'm having trouble replying w/ my software..
So, let's start a new thread.
My questions on spaceship control in close combat:
With advances in thruster control, would it be possible to fly like an
airplane? Would a space pilot use a stick like an airplane, with a
throttle? It seems like there is a big chance of being disoriented in
space.
So, is there a practical way of controlling all 3 axes/directions
of motion? I bet that some VR hardware designer already answered that
question, but you're welcome to contribute.
Also, some SF spaceships look like they would rip apart from the
torques involved in any tight maneuvers. Just look at the TIE fighters
from SW. If I was building that thing, I would put a few support bars of
<??> between those flimsy solar panels.
Max N.
Erik Max Francis
max wrote:
> As I said earlier, I'm having trouble replying w/ my software..
> So, let's start a new thread.
Well, my news server was down for a few days, so this is the first I've
seen of it in any case.
> My questions on spaceship control in close combat:
> With advances in thruster control, would it be possible to fly like an
> airplane? Would a space pilot use a stick like an airplane, with a
> throttle?
In a "spacefighter," you'd have potentially 4 degrees of control:
pitch, roll, yaw, and thrust.
In an airplane, you have maybe 3.5 degrees, but they aren't independent
(after all, many manuevers will make you stall): pitch (that's up and
down on the stick), roll (that's left and right on the stick), and
thrust (that's the throttle). With planes you also have the rudder, of
course, which is yaw, but my understanding is that it's used for
last-minute fine-tuning and such, rather than normal maneuvering.
> It seems like there is a big chance of being disoriented in
> space.
I don't think this is really the issue. Anyone flying a fighter,
spacefighter or not, is going to have training. Certainly something as
disorientation is not going to be a big problem. Fighters fly in, so to
speak, a cylindrical coordinate system, whereas spacefighters would fly
in a spherical coordinate system (no up or down whatsoever), but that
doesn't change the fact that the game is fundamentally
three-dimensional.
> So, is there a practical way of controlling all 3
> axes/directions
> of motion? I bet that some VR hardware designer already answered that
> question, but you're welcome to contribute.
I believe this has already been addressed in the Apollo space program,
and it worked fine: For attitude control, you have a stick (though for
the space program, I don't know offhand what assignments they used for
which controls). Up and down on the stick is pitch, left and right on
the stick is roll, and _twisting_ the stick left and right is yaw.
> Also, some SF spaceships look like they would rip apart from
> the
> torques involved in any tight maneuvers. Just look at the TIE fighters
> from SW. If I was building that thing, I would put a few support bars
> of
> <??> between those flimsy solar panels.
This goes without saying. These effects are greatly exaggerated in
popular science fiction film and TV, because, quite frankly, they're
trying to draw a parallel between what they're talking about and
something you can relate to -- fighter combat. The problem is, it would
be quite different. With fighters, you roll and pull up and you go into
a tight turn, because of the air control surfaces -- not the case at all
in vacuum. And there's no "cruising speed" -- you can go as fast as you
like. Considering the likely size of battlegrounds, you're talking some
serious deltavees accumulated between approaching forces.
In vacuum, your attitude is controlled only by your thrusting (and only
active control will keep you from spinning wildly, but of course this
will be automated). Thrust is applied in the direction you're facing,
and since this is now unrelated to your velocity, you can easily perform
all sorts of bizarre side shot and fake retreat maneuvers that you'd
never be able to in an atmosphere.
After all, in an atmosphere, you have to keep moving in the proper
direction and attack angle to remain flying. In vacuum it makes no
difference.
--
Erik Max Francis, &tSftDotIotE / mailto:m...@alcyone.com
Alcyone Systems / http://www.alcyone.com/max/
San Jose, California, United States / icbm://+37.20.07/-121.53.38
\
"Life may be / the product of imperfections."
/ (Marclo Gleiser)
Nyrath the nearly wise
Thus spoke max <ma...@erols.com>:
> So, is there a practical way of controlling all 3 axes/directions
> of motion? I bet that some VR hardware designer already answered that
> question, but you're welcome to contribute.
> torques involved in any tight maneuvers. Just look at the TIE fighters
> from SW. If I was building that thing, I would put a few support bars of
> <??> between those flimsy solar panels.
There was some discussion of this a couple of years
ago on rec.arts.sf.babylon-5 in reference to a proposed
"Starfury simulator". IIRC they settled on something
similar to the Apollo controls, as Max mentioned in
his post.
The Starfurys in Babylon 5 are large X shaped craft,
so as to get the attitude jets far from the center
of gravity in order to maximize the torque.
Babylon 5 is unique among TV shows as their
spaceships operate under Newtonian mechanics
instead of the ridiculous "fighter jet dogfight"
metaphor that is common. A Starfury's nose
is *not* always pointed along its line of flight.
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Isaac Kuo
Oh boy, my favorite r.a.sf.science topic yet again...
In article <34A22C1C...@alcyone.com>,
Erik Max Francis <m...@alcyone.com> wrote:
>max wrote:
>> My questions on spaceship control in close combat:
>> With advances in thruster control, would it be possible to fly like an
>> airplane? Would a space pilot use a stick like an airplane, with a
>> throttle?
It's theoretically possible, to an extent, but it would be like
controlling an helicopter as if it were a car. It just doesn't
match the capabilities and limitations of the vehicle well.
To a certain extent, the controls appropriate for a military
spacecraft depend upon what space combat given the assumed
situation would be like. It determines what sort of maneuvers
are significant and useful.
For example, it's possible for long range weapons to dominate space
combat, while the spacecraft have relatively low delta-v capabilities
(e.g. 10,000km+ range lasers with 1000sec Isp solid core engines).
In such situations, maneuvering during combat would have little effect,
so the maneuvering controls would best be oriented toward non-combat
maneuvering, like docking. For docking, delicate control in all 6
axes is appropriate, suggesting the use of 2 triple axis joysticks.
>In a "spacefighter," you'd have potentially 4 degrees of control:
>pitch, roll, yaw, and thrust.
Naturally, this assumes that a much higher thrust level is available
along a particular "strengthenned" axis than in other directions.
However, it's not immediately obvious that roll is necessarily
significant. Pitch and yaw point that thrust axis in a desired
direction, but roll doesn't do this.
>This goes without saying. These effects are greatly exaggerated in
>popular science fiction film and TV, because, quite frankly, they're
>trying to draw a parallel between what they're talking about and
>something you can relate to -- fighter combat. The problem is, it would
>be quite different. With fighters, you roll and pull up and you go into
>a tight turn, because of the air control surfaces -- not the case at all
>in vacuum. And there's no "cruising speed" -- you can go as fast as you
>like. Considering the likely size of battlegrounds, you're talking some
>serious deltavees accumulated between approaching forces.
Of course, you have to consider the delta-v limits of rockets, so you
can't really go as fast as you like.
And the conclusion about serious relative velocities between
approaching forces is assuming too much. The nature of space
combat with the available technology will dictate what relative
velocities are typical.
With guided missiles, it's plausible that a high relative speed
interception will be suicidal for both opposing forces--unless
one side thrusts away, giving that side an advantage (it's
missiles effectively get a boost by the other side persuing
while the other side's missiles effectively have to climb up a
hill). In this sort of situation, both sides may thrust to
reduce interception speed as standard tactics. This isn't the
only plausible possibility, but it is one plausible possibility.
One thing that isn't plausible is the opposite effect--a situation
where the persuer has the advantage. This is what happens in
aerial combat because aerodynamics give forward pointing weaponry
an advantage. This is why traditional air combat often begins
with a head on pass--if one side turns away, it merely gives the
other side a free shot.
Space combat is more likely to be more analagous to naval combat.
If missiles with similar maneuver capabilities as the targets are
the norm, it will be analagous to naval torpedo combat. Torpedoes
can be fired in any direction, but they are more effective if fired
from ahead of the target.
If long range weapons are the norm, it will be analagous to naval
missile combat. The ranges and speeds of the weapons are such that
tactical maneuvers are almost irrelevant.
--
_____ Isaac Kuo k...@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
__|_)o(_|__
/___________\ "Mari-san... Yokatta...
\=\)-----(/=/ ...Yokatta go-buji de..." - Karigari Hiroshi
Isaac Kuo
In article <67tgvi$q...@clarknet.clark.net>,
Nyrath the nearly wise <nyr...@clark.net> wrote:
>
> Babylon 5 is unique among TV shows as their
> spaceships operate under Newtonian mechanics
> instead of the ridiculous "fighter jet dogfight"
> metaphor that is common. A Starfury's nose
> is *not* always pointed along its line of flight.
Actually, if you look at how the spaceships move, it's obvious
they are NOT using newtonian mechanics. Even the Starfuries
usually move as if they were airplanes, and non-airplane-like
movement is treated as a "special maneuver" which catches the
other side by surprise.
This contrasts with a show like Gundam, which is much sillier
but does regularly depict the retrograde tactics which would
be the norm given the technology assumed. I think it's simply
because the fighters in Gundam don't look anything at all like
airplanes that they feel no obligation to make them move like
airplanes.
Wayne Throop
:: Nyrath the nearly wise <nyr...@clark.net>
:: Babylon 5 is unique among TV shows as their spaceships operate under
:: Newtonian mechanics instead of the ridiculous "fighter jet dogfight"
:: metaphor that is common. A Starfury's nose is *not* always pointed
:: along its line of flight.
: k...@bit.csc.lsu.edu (Isaac Kuo)
: Actually, if you look at how the spaceships move, it's obvious they
: are NOT using newtonian mechanics. Even the Starfuries usually move
: as if they were airplanes, and non-airplane-like movement is treated
: as a "special maneuver" which catches the other side by surprise.
What Isaac says is true, but I still think Nyrath has a strong point:
IMHO Babylon 5 is unique among TV shows as they are the only one that
even vaguely *tries* to get the dynamics right. As near as I can figure
out (from exchanges on the B5 newsgroups, sometimes exchanges with the
folks in charge of special effects for B5), the problem is only that
it's almost unknown among the staff that accelerations belly-up as
they are most often portrayed are implausible. So far sunk-in is the
viscous-fluid paradigm to most everybody's thinking. Not that this is
surprising: everybody *is* immersed in a viscous fluid. Everything
*does* come to rest eventually unless something pushes it, and so on,
just as Aristotle said. Newton is *not* obvious from common experience.
: This contrasts with a show like Gundam, which is much sillier but does
: regularly depict the retrograde tactics which would be the norm given
: the technology assumed. I think it's simply because the fighters in
: Gundam don't look anything at all like airplanes that they feel no
: obligation to make them move like airplanes.
That may well be. For example, in the first season of B5, the
raider's ships had airfoils (and were atmosphere-worthy as well
as space-worthy; hybrid craft), and they acted as if those air-foils
were effective, even in the scenes clearly extra-atmosphere. The
starfuries in season one acted a bit less airfoily, and they were
quite a bit less airfoiliferous in appearance.
Nits can be picked of course, even with the best of scenes,
but the starfury drop sequences in Midnight on the Firing Line,
and the tumbling derelict spaceship in Soul Hunter were just
*stunningly* good, compared to anything else in TV SF, or even
compared to most movie SF.
The effect with the raider's ships may be due to an unconcious bias,
which is what I take Isaac to suggest, or may even be an explicit,
intentional (but mistaken) effect; that is, the hybrid craft can bank
simply because they are designed with airfoils (I-presume-unknowingly
overlooking the fact that airfoils have to have air to foil to
function).
Similar things apply to the behavior of the hybrid "thunderbolt"
class starfuries introduced in late season 2 and season 3.
In more recent seasons, it has been the also-very-streamlined-and-
aeroodynamic-looking white star ships that "swoop"
as if banking against a fluid.
Mind you, the white stars have also had impressive shots of newtonian
behaviors, upon occasion. But there are also frequent lapses into
"banking" and "swooping". Aristotalian intuitions are deeply
built into most folks habits of thinking, and are hard to shake.
--
Wayne Throop thr...@sheol.org http://sheol.org/throopw
Mike
max wrote:
>
> As I said earlier, I'm having trouble replying w/ my software..
> So, let's start a new thread.
>
> With advances in thruster control, would it be possible to fly like an
> airplane? Would a space pilot use a stick like an airplane, with a
> space.
>
You'd be practically guaranteed to forget which way is up. Fortunately,
there is no "up." :)
You might have some trouble keeping track of how far you've turned, but
a decent HUD should fix that.
> Also, some SF spaceships look like they would rip apart from the
> torques involved in any tight maneuvers. Just look at the TIE fighters
> from SW. If I was building that thing, I would put a few support bars of
> <??> between those flimsy solar panels.
>
Bear in mind that there's no wind resistance...
Still, the TIE is a horrible design. The engines are way too close
together and the solar panels probably wouldn't be too useful in deep
space (they make great targets, though :)
I'm still trying to figure out where you fit the engines in a TIE...
--
-Mike
Unofficial Master of the Twist
Ordained Minister of the Universal Light Church
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Joseph Askew
Erik Max Francis (m...@alcyone.com) wrote:
: > My questions on spaceship control in close combat:
: > With advances in thruster control, would it be possible to fly like an
: > airplane? Would a space pilot use a stick like an airplane, with a
: > throttle?
: In a "spacefighter," you'd have potentially 4 degrees of control:
: pitch, roll, yaw, and thrust.
: In an airplane, you have maybe 3.5 degrees, but they aren't independent
: (after all, many manuevers will make you stall): pitch (that's up and
: down on the stick), roll (that's left and right on the stick), and
: thrust (that's the throttle). With planes you also have the rudder, of
: course, which is yaw, but my understanding is that it's used for
: last-minute fine-tuning and such, rather than normal maneuvering.
I would think that space fighters would be a lot closer to air
fighters because of the limits on engines. You can't have a lot
of big engines pointing in all directions. The main direction
of thrust you want will be the "forward" pointing one and so I
would assume you have the biggest engine you can wrap a fighter
body around. So you could just have a fighter control stick with
extra thrust. It would be easier to turn and run than to have yet
another large engine pointing the other way. The other controls
would be for small rockets like Apollo had which just provide the
ability to alter direction but provide no real thrust.
: > It seems like there is a big chance of being disoriented in
: > space.
: I don't think this is really the issue. Anyone flying a fighter,
: spacefighter or not, is going to have training. Certainly something as
: disorientation is not going to be a big problem. Fighters fly in, so to
: speak, a cylindrical coordinate system, whereas spacefighters would fly
: in a spherical coordinate system (no up or down whatsoever), but that
: doesn't change the fact that the game is fundamentally
: three-dimensional.
Fundamentally three dimensional for whom? Fighters don't really
fight all that much in three dimensions. The Atmosphere isn't
that thick, they can't fly that high, the places they want to
bomb or land on tend to be on the ground and hence pretty two
dimensional. Sure you have flying in from the sun sort of tricks,
but they aren't anywhere as important as what happens in space.
A fighter pilot on Earth always knows where "up" is. A fighter
pilot in space will have trouble remembering here his fleet is.
Even fighter pilots on Earth forget where the ground in is combat
and as dog fights tend to go lower and lower and lower smack into
terra firma (which implies they aren't keeping a weather eye on
their thrid dimension at all).
: This goes without saying. These effects are greatly exaggerated in
: popular science fiction film and TV, because, quite frankly, they're
: trying to draw a parallel between what they're talking about and
: something you can relate to -- fighter combat. The problem is, it would
: be quite different. With fighters, you roll and pull up and you go into
: a tight turn, because of the air control surfaces -- not the case at all
: in vacuum. And there's no "cruising speed" -- you can go as fast as you
: like. Considering the likely size of battlegrounds, you're talking some
: serious deltavees accumulated between approaching forces.
Between approaching forces yes. Although to make things hard to detect
you are probably better off in many case trying to be sneaky by
reducing your doppler shift. Whether it is radar, IR or even visual.
If apparent movement against the background is a cheap and easy way
to find your enemy that enemy will probably want to keep it to a
minimum.
: In vacuum, your attitude is controlled only by your thrusting (and only
: active control will keep you from spinning wildly, but of course this
: will be automated). Thrust is applied in the direction you're facing,
: and since this is now unrelated to your velocity, you can easily perform
: all sorts of bizarre side shot and fake retreat maneuvers that you'd
: never be able to in an atmosphere.
Weapons would also have an easier time of finding you. The early
IR homing AA missiles needed an engine lock. The newer ones don't,
they can get a side shot because the IR detectors are much colder.
In space that won't be such a problem so you can fire in any
direction you like and hit your enemy at any point. So there will
be a lot more tricky "flying" and a hell of a problem keeping your
velocity relative to your friends, the enemy, their larger ships
et al in mind but I doubt it will be that different.
: After all, in an atmosphere, you have to keep moving in the proper
: direction and attack angle to remain flying. In vacuum it makes no
: difference.
Very true. It might be a mistake to provide such an obvious thing
to spot as an exhaust from a constantly working engine in space too.
Joseph
--
Apparently there is some sort of holiday to celebrate the
crucifixion of Santa or something. Whatever. Have a happy holiday!
Isaac Kuo
In article <8830...@sheol.org>, Wayne Throop <thr...@sheol.org> wrote:
>:: Nyrath the nearly wise <nyr...@clark.net>
>:: Babylon 5 is unique among TV shows as their spaceships operate under
>:: Newtonian mechanics instead of the ridiculous "fighter jet dogfight"
>:: metaphor that is common. A Starfury's nose is *not* always pointed
>:: along its line of flight.
>: k...@bit.csc.lsu.edu (Isaac Kuo)
>: Actually, if you look at how the spaceships move, it's obvious they
>: are NOT using newtonian mechanics. Even the Starfuries usually move
>: as if they were airplanes, and non-airplane-like movement is treated
>: as a "special maneuver" which catches the other side by surprise.
>What Isaac says is true, but I still think Nyrath has a strong point:
>IMHO Babylon 5 is unique among TV shows as they are the only one that
>even vaguely *tries* to get the dynamics right.
Unique among U.S. TV shows, perhaps. But it isn't much of an attempt.
>As near as I can figure
>out (from exchanges on the B5 newsgroups, sometimes exchanges with the
>folks in charge of special effects for B5), the problem is only that
>it's almost unknown among the staff that accelerations belly-up as
>they are most often portrayed are implausible.
No, the main problem is that the vehicles usually point in the
direction of motion, instead of the direction of acceleration.
Given the maneuvers depicted, the direction of acceleration is
almost always normal to the direction of motion.
The most serious and blatant faults occur whenever a ship approachs
B5 or another fixed point. Invariably, the ship points _toward_
the destination point. Realistically, in order to stop the ship
must thrust _away_ from the destination point. The only ships with
"reverse" thrusters are the Starfuries, and we never see them burn
those forward pointing thrusters to slow down.
Another problem is the maneuvers depicted, but this is a more
theoretical one. Retrograde maneuvers are never depicted, despite
the fact that they make infinitely more sense than "running away"
from a target with the weapons pointed directly away from the target.
>So far sunk-in is the
>viscous-fluid paradigm to most everybody's thinking. Not that this is
>surprising: everybody *is* immersed in a viscous fluid. Everything
>*does* come to rest eventually unless something pushes it, and so on,
>just as Aristotle said. Newton is *not* obvious from common experience.
It actually is pretty intuitive if you play a non-viscous version of
Space War (one which doesn't have a "drag" factor).
>: This contrasts with a show like Gundam, which is much sillier but does
>: regularly depict the retrograde tactics which would be the norm given
>: the technology assumed. I think it's simply because the fighters in
>: Gundam don't look anything at all like airplanes that they feel no
>: obligation to make them move like airplanes.
>That may well be. For example, in the first season of B5, the
>raider's ships had airfoils (and were atmosphere-worthy as well
>as space-worthy; hybrid craft), and they acted as if those air-foils
>were effective, even in the scenes clearly extra-atmosphere. The
>starfuries in season one acted a bit less airfoily, and they were
>quite a bit less airfoiliferous in appearance.
No, the starfuries definitely look vaguely airplane like. They've
got wings! Also, anything which is relatively flat and/or elongated
looks sort of airplane like.
Non-airplane like things are wingless vehicles which are relatively
tall (they look vaguely ship-like), simple geometrical objects (e.g.
the Borg cube), and humanoid shapes.
>Nits can be picked of course, even with the best of scenes,
>but the starfury drop sequences in Midnight on the Firing Line,
>and the tumbling derelict spaceship in Soul Hunter were just
>*stunningly* good, compared to anything else in TV SF, or even
>compared to most movie SF.
A few isolated incidents don't make up for continual errors,
nor does relative favorable comparison to other shows.
>The effect with the raider's ships may be due to an unconcious bias,
>which is what I take Isaac to suggest, or may even be an explicit,
>intentional (but mistaken) effect;
I think it's mainly that the people doing the SFX just don't
understand what motion in a vacuum is like.
>Mind you, the white stars have also had impressive shots of newtonian
>behaviors, upon occasion. But there are also frequent lapses into
>"banking" and "swooping". Aristotalian intuitions are deeply
>built into most folks habits of thinking, and are hard to shake.
Actually, the ideas of banking aren't intuitive either. They are
only intuitive because of experience with airplane flight. If one
were only experienced with ship or car motion, it would be intuitive
to bank vessels in the opposite direction!
ea...@neosoft.com
But only if you are dealing with surface ships. Submarines "bank" in
a manner similar to airplanes. They start the turn with a tilt
outwards like surface ships but after a second or so the side pressure
on the sail causes the sub to snap to a airplane like turn configuration
with the sail inside the radius of curvature. Interesting effect(!!!), and
the use of the seatbelts is highly recomended during a 45degree down angle.
Leonard Erickson
max <ma...@erols.com> writes:
> As I said earlier, I'm having trouble replying w/ my software..
> So, let's start a new thread.
>
> My questions on spaceship control in close combat:
> With advances in thruster control, would it be possible to fly like an
> airplane? Would a space pilot use a stick like an airplane, with a
> throttle? It seems like there is a big chance of being disoriented in
> space.
You *can't* fly a spaceship like an airplane, simply because the
dynamics involved are so different.
An airplane has a source of thrust, and then steers by interacting with
the air.
A spaceship has a source of thrust and uses thrusters to *change
orientation*. The trick is that if you are moving at velocity V in
direction X, You will cntinue to move that way *without* any power.
Your course will be modified somewhat if you are near a planet or star.
Your ship can be pointing in *any* direction.
To make a course change, you swing the ship around so the main drive
points in the correct direction (not the one most people would think!)
and fire the drive until you are moving on the new course.
The thing is, the only forces you experience, except for minor forces
as you turn the ship are all *straight back*. That is, "down" is
towards the tail of the ship. If you change orientation while the main
drive is going, the thrusters wiull only change this direction
*slightly*. (BTW, this means the spacecraft pilot can pull a *lot* more
Gs than an aircraft pilot)
Now as to that course change. Lets say you are going "north" at speed
X, and you want to be going east at speed X.
So you swing the ship so that the tail points *southwest*. And you fire
the main drive until you are going in the right direction at the right
speed. It's elementary vector addition, but it's *not* what most folks
would think of as the "right" way for objects to move.
So you can see that *all* the manuevers in Star Wars, Battlestar
Galactica, Star Trek, etc are *wrong*.
Things get even *more* counter-intuitive when you are making maneuvers
while in close orbit. Then you get weird things like slowing down takes
you farther out.
--
Leonard Erickson (aka Shadow)
sha...@krypton.rain.com <--preferred
leo...@qiclab.scn.rain.com <--last resort
Wayne Throop
:: Wayne Throop <thr...@sheol.org>
:: IMHO Babylon 5 is unique among TV shows as they are the only one that
:: even vaguely *tries* to get the dynamics right.
: k...@bit.csc.lsu.edu (Isaac Kuo)
: Unique among U.S. TV shows, perhaps. But it isn't much of an attempt.
It's a deeply flawed attempt, yes. Still an order of magnitude better
than any other US TV show known to me.
:: the problem is only that it's almost unknown among the staff that
:: accelerations belly-up as they are most often portrayed are
:: implausible.
: No, the main problem is that the vehicles usually point in the
: direction of motion, instead of the direction of acceleration.
Duh. That's what I said; "belly up" accelleration; the acceleration
points from the belly, "up"; acceleration points radially and the ships
nose points tangentially.
: It actually is pretty intuitive if you play a non-viscous version of
: Space War (one which doesn't have a "drag" factor).
OK. Now, how do you get the FX staff to play long enough to get
their intuitions rewired?
:: The starfuries in season one acted a bit less airfoily, and they were
:: quite a bit less airfoiliferous in appearance.
: No, the starfuries definitely look vaguely airplane like.
Read my lips. I didn't say they didn't look vaguely airplane-like.
I said they looked LESS airplane-like than the raider craft.
Even more specifically, my point was about the surface area that
looked like an airfoil.
: They've got wings!
They've got support struts, which are thicker in the direction
of greatests stress from the engines, as indeed they need to be.
: Also, anything which is relatively flat and/or elongated looks sort of
: airplane like.
The first season starfury pilot compartment is angular instead of streamlined,
broad and squat rather than long and pointy, and the pilot is spreadeagled
perpendicular to the line of sight/acceleration. This is not really all that
airplane-like.
The engines are long, and are shrouded rather than having their "guts"
hanging out; they are the most atmosphere-immersed-looking part of the
gadget. And even they have features obviously viable only in vacuum,
like the long vanes that stick into the exhaust stream.
In any event, to complain about anything that looks "relatively flat
and/or elongated" as being "airplane-like" and hence a bad portrayal
of a spacecraft wouldn't be reasonable, IMO.
: A few isolated incidents don't make up for continual errors,
The incidents aren't as isolated as this makes it seem, IMHO,
and they make it easier for me to grit my teeth past the frequent errors.
: Actually, the ideas of banking aren't intuitive either. They are only
: intuitive because of experience with airplane flight.
Well, DUH! That's what intuition IS: expectation based on experience.
Further, you don't need experience with aircraft to know you lean into a turn,
and accelerations are always from the belly of the craft and point "up";
that experience is nigh-universal, airplanes or no.
Erik Max Francis
Joseph Askew wrote:
> : In a "spacefighter," you'd have potentially 4 degrees of control:
> : pitch, roll, yaw, and thrust.
...
> I would think that space fighters would be a lot closer to air
> fighters because of the limits on engines. You can't have a lot
> of big engines pointing in all directions. The main direction
> of thrust you want will be the "forward" pointing one and so I
> would assume you have the biggest engine you can wrap a fighter
> body around. So you could just have a fighter control stick with
> extra thrust. It would be easier to turn and run than to have yet
> another large engine pointing the other way. The other controls
> would be for small rockets like Apollo had which just provide the
> ability to alter direction but provide no real thrust.
Uh, that's what I said. Pitch, roll, and yaw are all angular degrees of
freedom -- that is, they're attitude controls, not thrust controls.
Pitch, roll, yaw, and thrust.
If I were talking about _independent_ x-, y-, and z-axis translation
_and_ angular control, that's six degrees of freedom. I was only
talking about four, and only one of them involves translation.
> Fundamentally three dimensional for whom? Fighters don't really
> fight all that much in three dimensions.
Fundamentally three-dimensional in that if you are in a dogfight and
don't pay attention to up and down you get shot down.
> The Atmosphere isn't
> that thick, they can't fly that high, the places they want to
> bomb or land on tend to be on the ground and hence pretty two
> dimensional.
Airplane flight is sort of 2.5-dimensional, because the third dimension
isn't as significant as the others, true (this is what I was trying to
get at when I talked about it being in a cylindrical coordinate system
as opposed to a fully-spherical one).
However, it doesn't change the fact that in airplane flight the third
dimension is important.
> Between approaching forces yes. Although to make things hard to detect
> you are probably better off in many case trying to be sneaky by
> reducing your doppler shift. Whether it is radar, IR or even visual.
> If apparent movement against the background is a cheap and easy way
> to find your enemy that enemy will probably want to keep it to a
> minimum.
Well, there are obviously the stealth tactics that frequently get
discussed in this group. I was talking about spacefight combat in a
traditional sense (two forces spot each other, and send out fighters).
The tactics of maneuvering your ship into a position where you have
"higher ground" than the enemy is obviously a significant aspect, and
would be much more reminiscent of submarine warfare (where stealth is
everything) than anything like airplane or surface naval combat.
> Weapons would also have an easier time of finding you. The early
> IR homing AA missiles needed an engine lock. The newer ones don't,
> they can get a side shot because the IR detectors are much colder.
> In space that won't be such a problem so you can fire in any
> direction you like and hit your enemy at any point. So there will
> be a lot more tricky "flying" and a hell of a problem keeping your
> velocity relative to your friends, the enemy, their larger ships
> et al in mind but I doubt it will be that different.
Yes, we all know this. I'm talking spacefighter dogfighting tactics, as
opposed to strategic tactics.
Paul Dietz
The biggest problem I have with SF depictions of space
battles is not that the vehicles are airplane-like,
but that they have human pilots at all. They're talking about
unmanned aircraft for combat *today*; in the far future
when space combat could occur computers will be orders
of magnitude better.
Un-(human)-piloted spacecraft could be very much smaller
than human piloted vehicles, able to accelerate faster,
able to "hibernate" at low power consumption, be
less expensive, have much faster reaction times,
and be more expendable.
Paul
"Once, galactic empires might have seemed a
Post-Human domain. Now, sadly, even interplanetary
ones are."
-- V. Vinge, on the Singularity
Grosberg
Isaac Kuo wrote:
>
> The only ships with
> "reverse" thrusters are the Starfuries, and we never see them burn
> those forward pointing thrusters to slow down.
>
but somehow they manage to get to a complete stop in a matter of
seconds - an acceleration that no human body can withstand.
max
To : Paul Dietz <di...@interaccess.com>
Cc :
Attchmnt:
Subject : Re: Realictic space battles / ships
----- Message Text -----
On Fri, 26 Dec 1997, Paul Dietz wrote:
> Makism Nilov wrote: (that's Maksim)
> >
> > Yes, the human pilots may be hard to keep alive, but what kind of computers
> > would you need? AI? Expert systems? Yeah, I can see robot craft as sentries,
> > but attacking would be tough for cpu's. Even in a simplified battlefield
> > of interplanetary space, you would need to devise strategies. Perhaps AI
> > would be capable of this, but attackng ground targets would be a toughie.
>
> By the time these kind of fantastic spacecraft are available
> (if ever), computers will have far surpassed the human brain.
> At current rates of change we're 30 years or so from parity
> (some assumptions there). Are we going to have space fighters
> in 30 years? I don't think so.
Oh really? I doubt that computers will ever surpass the human brain. To do
so would be to.. go against nature's fundamental principles of natural intelligence.
You may consider your PC as thinking, but there is a big argument about whether it
is sentient. It is hard to figure out what "sentient" means when the "mind" is
fragmented, or when a sum of relatively unintelligent parts is viewed as intelligent.
One could say that plants are "conscious", while another may describe it as
phototropic. Of course, here the first person would have less of a background in
biology, but perhaps would be something of an imaginative psychologist. The second
person may be the opposite in character to speaker # 1. Personally, I think that
computer AI will stay as just that : *artifical* intelligence. Or perhaps quite demented
like HAL 9000 (2001 Space Odyssey). You wouldn't want a truly intelligent computer in a
powerful fighter , one that's able to go beyound its programming. What if you have a
major malfunction in 50 ships networked together (packet collision, anyone?:)
> Why is attacking ground targets a toughy? Organisms less
> complex than humans do it all the time. Because, can you imagine your comparatively little craft's vision
system trying to deal with finding targets? On the other hand, you could
use something like a radar system ripped off a cruise missile. No, that's
too simplistic..
1)cruise missiles fly very low - what if the craft needs to enter atmosphere?
2)would radar work in space? I would imagine that you would need
an IR vision system, because radar waves would have very little matter
from which to bounce off. Perhaps IR would not be enough and there will
be a need to interpret other sources of radiation.
Max N
Isaac Kuo
In article <34A43041...@alcyone.com>,
Erik Max Francis <m...@alcyone.com> wrote:
>Airplane flight is sort of 2.5-dimensional, because the third dimension
>isn't as significant as the others, true (this is what I was trying to
>get at when I talked about it being in a cylindrical coordinate system
>as opposed to a fully-spherical one).
>However, it doesn't change the fact that in airplane flight the third
>dimension is important.
In some senses, the third dimension is more significant than the other
two in aerial combat. In ACM, it's fundamentally different from the
other dimensions, and different aircraft can have different
"maneuverability" in the horizontal and vertical dimensions. Some
airplanes have superior climb capability, and some have superior
turning ability. A dogfight between a Phantom II and Mig-19 is a
typical example of superior power vs. superior turning ability. The
Phantom needs to use the third dimension and energy tactics in
order to compete.
In space, there isn't any special third dimension, and there isn't
any distinction between forward and lateral acceleration ability.
There also isn't a big distinction between "slow" and "fast", nor
a distinction between "in front of" and "behind" the enemy.
Tactical maneuvers in space combat would thus be less rich than
those in aerial combat.
Isaac Kuo
In article <8831...@sheol.org>, Wayne Throop <thr...@sheol.org> wrote:
>: k...@bit.csc.lsu.edu (Isaac Kuo)
>: Unique among U.S. TV shows, perhaps. But it isn't much of an attempt.
>:: the problem is only that it's almost unknown among the staff that
>:: accelerations belly-up as they are most often portrayed are
>:: implausible.
>: No, the main problem is that the vehicles usually point in the
>: direction of motion, instead of the direction of acceleration.
>Duh. That's what I said; "belly up" accelleration; the acceleration
>points from the belly, "up"; acceleration points radially and the ships
>nose points tangentially.
I didn't understand what you meant by "belly-up"--I thought you were
refering to something biological.
I still don't understand where you get this "belly-up" expression
from. "Up", I can understand, but the accelerating in the opposite
direction of the belly. It would be "belly-down", if anything ("up"
is the direction of acceleration, the belly of the craft is down).
Anyway, this term is confusing, and I'd use the term "dorsal
acceleration" instead.
Anyway, this term doesn't describe what is depicted in SciFi
(including B5). What is depicted is simply that a vessel will
tend to go "forward" when it turns. If a vessel pitches up, then
that would be depicting "belly-up" acceleration. However, most
SciFi, including B5, tends to depict sideways turns a lot more
than upward turns. Thus, the vessel will yaw (often with an
airplane-like banking motion), and the craft will in fact
accelerate sideways. Since the banking is almost never a full
90 degrees, the direction of acceleration is at an angle from
dorsal.
>: It actually is pretty intuitive if you play a non-viscous version of
>: Space War (one which doesn't have a "drag" factor).
>OK. Now, how do you get the FX staff to play long enough to get
>their intuitions rewired?
You don't need to. All you need is ONE FX staffer to get things
right, along with the writers (preferably). He then storyboards
the FX for everyone else.
[about Starfuries]
>: They've got wings!
>They've got support struts, which are thicker in the direction
>of greatests stress from the engines, as indeed they need to be.
They look like wings.
Anyway, support struts wouldn't need to be "solid". As is depicted
in many other B5 Earthforce vessels, a strutted structure would
save weight for equivalent strenth. Even better, the engines could
have been placed right next to the hull, resulting in even more
saved weight.
>: Also, anything which is relatively flat and/or elongated looks sort of
>: airplane like.
>The first season starfury pilot compartment is angular instead of streamlined,
>broad and squat rather than long and pointy, and the pilot is spreadeagled
>perpendicular to the line of sight/acceleration. This is not really all that
>airplane-like.
The overall appearance is still streamlined and airplane-like. For
comparison, Babylon 5 itself, the Minbari cruisers, and EA
destroyers don't look very airplane-like.
>In any event, to complain about anything that looks "relatively flat
>and/or elongated" as being "airplane-like" and hence a bad portrayal
>of a spacecraft wouldn't be reasonable, IMO.
No, I don't mind spacecraft looking vaguely airplane-like. I'm just
noting that it's one reason they are depicted such that they move
like airplanes.
>: Actually, the ideas of banking aren't intuitive either. They are only
>: intuitive because of experience with airplane flight.
>Well, DUH! That's what intuition IS: expectation based on experience.
>Further, you don't need experience with aircraft to know you lean into a turn,
>and accelerations are always from the belly of the craft and point "up";
>that experience is nigh-universal, airplanes or no.
If that were the case, then there wouldn't be any debate among personal
watercraft hobbyists between leaning into vs. leaning out of a turn.
Believe it or not, there are a lot of casual riders who merely turn the
steering bars and let the vehicle lean out according to its natural
tendency. I suppose the sensation makes it feel like one is "turning
more".
Anyway, automobiles and ships lean out of a turn, even if an experienced
driver will lean into the turn.
Isaac Kuo
In article <34A4C4...@erols.com>, max <ma...@erols.com> wrote:
>>>Yes, the human pilots may be hard to keep alive, but what kind of
>>>computers would you need? AI? Expert systems? Yeah, I can see robot
>>>craft as sentries, but attacking would be tough for cpu's. Even in
>>>a simplified battlefield of interplanetary space, you would need
>>>to devise strategies. Perhaps AI would be capable of this, but
>>>attackng ground targets would be a toughie.
I'd think a typical home computer from today would probably be
sufficient. The main problem is programming. Space combat has
a rather limited scope, with little "background clutter" and
simple mission goals, much like naval or air-air combat.
>>By the time these kind of fantastic spacecraft are available
>>(if ever), computers will have far surpassed the human brain.
>>At current rates of change we're 30 years or so from parity
>>(some assumptions there). Are we going to have space fighters
>>in 30 years? I don't think so.
Computers have already far surpassed the human brain in some
respects. In other respects, which are essentially
software-related, computers aren't on the level of a demented
turkey. What's more significant is that in some of those
respects, we aren't making any progress and we don't know when
we will make any progress.
>Oh really? I doubt that computers will ever surpass the human
>brain. To do so would be to.. go against nature's fundamental
>principles of natural intelligence.
What are those principles?
>You may consider your PC as thinking, but there is a big
>argument about whether it is sentient. It is hard to figure out
>what "sentient" means when the "mind" is fragmented, or when a
>sum of relatively unintelligent parts is viewed as intelligent.
Sentience is irrelevant, at least as far as space combat is
concerned. Figuring out and enacting strategy in space combat
is a problem to be solved, not a philisophical debate. For
example, no one would reasonably consider a Sidewinder missile's
built in computer to be intelligent or sentient. Nonetheless,
it's adequate for solving the problem it's assigned.
Indeed, you wouldn't want to put a sentient entity deserving
full human rights in harms way any more than you'd want to put
a human being in harms way (assuming such things could exist--IMO
they could).
>You wouldn't want a truly intelligent computer in a powerful fighter,
>one that's able to go beyound its programming.
Why not? We already put human beings in powerful fighters, exclusively!
Fighter pilots are definitely truly intelligent, and capable of going
beyond any "programming" (i.e. orders).
>What if you have a major malfunction in 50 ships networked
>together (packet collision, anyone?:)
Why would they be networked together any more than today's manned
equipment?
>>Why is attacking ground targets a toughy? Organisms less
>>complex than humans do it all the time.
>Because, can you imagine your comparatively little craft's vision
>system trying to deal with finding targets?
Yes. Computer vision is currently rather primitive, but we're making
progress. It's not inconceivable that we could have computer vision
good enough to field on the battlefield in acquisition systems within
a decade.
>On the other hand, you could
>use something like a radar system ripped off a cruise missile. No, that's
>too simplistic..
> 1)cruise missiles fly very low - what if the craft needs
>to enter atmosphere?
> 2)would radar work in space? I would imagine that you would need
>an IR vision system, because radar waves would have very little matter
>from which to bounce off. Perhaps IR would not be enough and there will
>be a need to interpret other sources of radiation.
Radar works just fine in space. The lack of matter from which to
bounce off of is a bonus--it reduces how much background clutter
there is to deal with.
Bill Dugan
On Fri, 26 Dec 1997 19:00:07 GMT, thr...@sheol.org (Wayne Throop)
wrote:
snip
>OK. Now, how do you get the FX staff to play long enough to get
>their intuitions rewired?
You don't. You give them a slightly modified version of that
non-viscous Space War to use for planning the ship motion.
Paul Dietz
max wrote:
> Oh really? I doubt that computers will ever surpass the human brain. To do
> so would be to.. go against nature's fundamental principles of natural intelligence.
"Nature's fundamental principles of natural intelligence?"
There were some things machines were not meant to do, eh?
The 30 year claim comes from estimating the amount of processing
going on in the brain (this is where the assumptions come
in -- it's not known for sure how much processing is occuring
at the subcellular level). There are about 10^14 synapses
in the brain, each firing at about 10 s^-1, for about 10^15
basic operations per second. If memory is stored in synapses,
say ten bits per synapse, this is also about 10^15 bits.
So, peta-op computers, peta-bit memories, and peta-bps
communications to connect them (but much of that is local;
long range communication in the brain is in the hundreds
of gigabps, over axons that are less numerous than synapses).
Today's supercomputers are in the tera-op range of computation,
and tens or hundreds of gigabits of RAM. Estimate that
computer attributes are improving by roughly a factor of
100 each decade. 10^15 bits of RAM might cost $400 M today,
but should be affordable in two or three decades.
AI has failed so far in part because the machines just aren't
powerful enough, by many orders of magnitude. But thinking
that this will remain true when computers do acquire, then
exceed, the raw processing power of the brain is, I think,
something of a head-in-the-sands attitude. Exponential
improvement means the time of parity will arrive much sooner
than you might think.
You can rightly point out that this machine will have to
be programmed. I look to the neuroscience community for
inspiration there. Knowledge of the function of the brain
is doubling every ten years. Most of what will be known
about the brain 30 years hence is unknown today.
NASA and various universities have a petaflop supercomputer
project, btw.
Paul
Paul Dietz
Isaac Kuo wrote:
> Computers have already far surpassed the human brain in some
> respects. In other respects, which are essentially
> software-related, computers aren't on the level of a demented
> turkey. What's more significant is that in some of those
> respects, we aren't making any progress and we don't know when
> we will make any progress.
I think we are making tremendous progress at reverse engineering
the brain. It's a big job, and is being done by neurobiologists,
not AI researchers, but progess is continual and accelerating.
This doesn't have much to do with good-old-fashioned-AI, but then
there's no reason why gofAI has to be THE approach to making
intelligent machines.
Paul
Charles Mark Bee
>
> >: It actually is pretty intuitive if you play a non-viscous version of
> >: Space War (one which doesn't have a "drag" factor).
>
> >their intuitions rewired?
>
> right, along with the writers (preferably). He then storyboards
> the FX for everyone else.
>
soap opera and snaps "what the hell is that thing? I want my spaceships
to move like they're threatening, you know, ZOOM, SWISH!! ..And where's
the damn wings? Nobody's going to be afraid of a tin can, dammit!"
Believe me, I do some design and FX for TV, and you never get to do
what you want.
Besides, space fighters are robotic, small, spherical, with one
thruster and a real fast gyro. They cost about like a sparrow missile
to build except for the sensory platform. So there! =-)
I think most attempts at greater complexity will rapidly fall prey to a
score of these little numbers... -CMB
Samuel
<Snip>
> > 2)would radar work in space? I would imagine that you would need
> >an IR vision system, because radar waves would have very little matter
> >from which to bounce off. Perhaps IR would not be enough and there will
> >be a need to interpret other sources of radiation.
>
> Radar works just fine in space. The lack of matter from which to
> bounce off of is a bonus--it reduces how much background clutter
> there is to deal with.
The main problem with radar in space is the large amount of area to
cover. In a hypothetical space battle the ships are spread across tens
of thousands (if not hundreds of thousands) of kilometers. This would
require a large amount of energy, much more than might be practical.
Even if it were practical the ship would stand out like a beacon; easy
pichins' for any reasonably stealthed ship.
In space warfare silence, invisibility and PASSIVE sensors would be the
rule...
Grosberg
Bill Dugan wrote:
>
> On Fri, 26 Dec 1997 19:00:07 GMT, thr...@sheol.org (Wayne Throop)
> wrote:
>
> snip
>
> >their intuitions rewired?
>
> non-viscous Space War to use for planning the ship motion.
How do FX people plan ship movement in, say, B5? As someone who uses
3d CGI I can say that it's not easy to create realistic space flight
unless you have some simulator that has newtonian mechanics programmed
into it, and could transfer the data to the 3d program.
With just the 3d program itself (B5 uses "lightwave"), it's easier to
assign the ship a path and then order it to bank according to that
path.
Wayne Throop
: k...@bit.csc.lsu.edu (Isaac Kuo)
: I still don't understand where you get this "belly-up" expression
: from. "Up", I can understand, but the accelerating in the opposite
: is the direction of acceleration, the belly of the craft is down).
Yes, now you point it out to me, the term I used is misleading at best.
I'll think up something else; "transverse acceleration" or somesuch.
My mental image was much like that for (say) "westerly" winds.
The wind doesn't blow *towards* the west, it comes *from* the west;
the acceleration comes from the "belly" (or what looks like
a ventral surface) "up". But again: I agree it's not a good term,
and I'll switch.
: Anyway, this term doesn't describe what is depicted in SciFi
: (including B5). What is depicted is simply that a vessel will tend to
: go "forward" when it turns. If a vessel pitches up, then that would
: be depicting "belly-up" acceleration.
I disagree. The problem is exactly as I've described it before in more
specific detail; Take a trajectory in what we'll assume is an inertial
camera view. Take a segment of that trajectory and approximate it by
the most similar segment of a circular trajectory. Now, that
approximated trajectory now has a "radius" and a "tangent" at the point
where the vessel is. The problem is, the acceleration depicted is
radial (even "centripetal"), but the orientation of the vessel (and its
engines and depicted reaction exhaust) is tangential. Big oops.
There is the additional problem of a "phantom acceleration" from
pointing upSCREEN. But that's usually a more minor problem,
at least when I single-step and look carefully at orientations.
Hence, little oops.
[about Starfuries]
::: They've got wings!
:: They've got support struts, which are thicker in the direction of
:: greatests stress from the engines, as indeed they need to be.
: They look like wings.
Well. Not to me.
: Anyway, support struts wouldn't need to be "solid".
But there are legitimately-arguable reasons for them to be,
and for the engines to be shrouded by solid covers.
For one simple example, if the strength/weight tradeoffs are already
made at the "foamed materials" level, rather than with macroscopic
cutouts. For even ablating under attack, for another.
: Even better, the engines could have been placed right next to the
: hull, resulting in even more saved weight.
Making a single-hit disabling shot easier, as well as
possibly compromising pilot exposure to whatevertheheck.
: The overall appearance is still streamlined and airplane-like.
Not to my eye.
: Anyway, automobiles and ships lean out of a turn, even if an
: experienced driver will lean into the turn.
Uh... I disagree on two points. Ship buoyancy should tend to point
them up the acceleration vector, just as helium balloons head towards
the *back* off the car when it brakes. And while cars "lean out of a
turn" people *in* the cars do not (in my observation). It's "obvious"
that the car's lean outwards is pathological, and the less it happens,
the better, while the boat,bike,runner,passenger,eurotrain,whatever's
lean inwards is stabilizing.
John Schilling
Samuel <davi...@pilot.msu.edu> writes:
><Snip>
Passive sensors, yes. Invisibility, not likely. The energies required
to move a spacecraft across astronomical distances are, well, astronomical,
and there is not much of a background to hide them in. Against an enemy
with even modest passive sensors, it is not possible for a spacecraft
to remain hidden unless it remains motionless and inactive - the last
time I worked the numbers, even minor tactical maneuvers would have to
be planned and executed over the course of a week or so, in order to
avoid detection.
One can imagine rare, contrived scenarios where 'stealth' spaceships
lurking in ambush might prove useful, but for the most part mobility
is likely to be more valuable. A static force, as any space fleet
attempting to remain invisible must be, can almost invariably be
defeated in detail by a mobile adversary capable of concentrating
its forces at will.
--
*John Schilling * "You can have Peace, *
*Member:AIAA,NRA,ACLU,SAS,LP * or you can have Freedom. *
*University of Southern California * Don't ever count on having both *
*Aerospace Engineering Department * at the same time." *
*schi...@spock.usc.edu * - Robert A. Heinlein *
*(213)-740-5311 or 747-2527 * Finger for PGP public key *
Wayne Throop
:: OK. Now, how do you get the FX staff to play long enough to get
:: their intuitions rewired?
: wkd...@ix.netcom.com (Bill Dugan)
: You don't. You give them a slightly modified version of that
: non-viscous Space War to use for planning the ship motion.
I doubt that would work. Without their intuitions at least
deprogrammed, if not REprogrammed, they'd simply reject the
motions it planned for them, as bing "wrong-looking".
In short, they wouldn't trust it or use it.
No, no, there's no other alternative. They need to be sent
to a Reeducation Center, where gentle positive reinforcement,
and concerned, sympathetic negative reinforcement (but only where
absolutely needed of course) would be used to reorient their thinking
to come in line with the Newtonian Norm.
For their own good, of course.
Paul Dietz
John Schilling wrote:
> Against an enemy
> with even modest passive sensors, it is not possible for a spacecraft
> to remain hidden unless it remains motionless and inactive - the last
> time I worked the numbers, even minor tactical maneuvers would have to
> be planned and executed over the course of a week or so, in order to
> avoid detection.
Remain motionless? You mean not accelerate.
It would be interesting to hear the assumptions that went
into you calculation.
Paul
John Schilling
Paul Dietz <di...@interaccess.com> writes:
>John Schilling wrote:
>> Against an enemy
>> with even modest passive sensors, it is not possible for a spacecraft
>> to remain hidden unless it remains motionless and inactive - the last
>> time I worked the numbers, even minor tactical maneuvers would have to
>> be planned and executed over the course of a week or so, in order to
>> avoid detection.
>Remain motionless? You mean not accelerate.
You pick your reference frame, I'll pick mine :-)
More generally, substitute "unable to respond to enemy actions or otherwise
exploit any advantage you might have gained by remaining hidden in the first
place". Unless your initial trajectory just happens to put you where you
need to be when you need to be there (unlikely, especially if the enemy
isn't playing the stealth game and thus is free to move as he sees fit),
you either try to fight from a decidedly sub-optimal position or you
blow your cover when you light up the engines.
"Decidedly sub-optimal position", most likely meaning either out of range
and watching helplessly as the enemy accomplishes his objective unhindered,
or smack in the path of an overwhelming enemy force that will squash you
like a bug even if surprise does give you the first shot.
>It would be interesting to hear the assumptions that went
>into you calculation.
I'll see if I can dig up the original post, but IIRC I assumed a baseline
"space cruiser" massing a thousand tons, equipped with a passive sensor
comparable to a two-meter astronomical telescope (note that two-meter
telescopes fit neatly into ten-ton spysats; plenty of room on a cruiser).
Propulsion was by a doubletalk drive capable of any performance desired
save that it had to comply with Newtonian physics, and that no more than
99% of the drive energy could be shielded or redirected from the enemy's
sensors. I considered both major and minor tactical maneuvers, with
"major" cosntituting a net change in position equal to the initial
engagement range and "minor" one percent of that.
That last assumption, incidentally, takes actual range out of the equation.
The farther away you are, the easier it is to hide any given emission of
energy, but the more energy it takes to move far enough to accomplish
anything. Everything cancels, except the time over which a maneuver
must be spread out in order to avoid detection. Which came out to months
for major and days for minor tactical maneuvers.
And playing with the assumptions, talking space fighters rather than
space cruisers, giving the stealth guys 99.9% efficient drives, whatever,
didn't actually change very much.
Erik Max Francis
Wayne Throop wrote:
> I disagree. The problem is exactly as I've described it before in
> more
> specific detail; Take a trajectory in what we'll assume is an inertial
> camera view. Take a segment of that trajectory and approximate it by
> the most similar segment of a circular trajectory. Now, that
> approximated trajectory now has a "radius" and a "tangent" at the
> point
> where the vessel is. The problem is, the acceleration depicted is
> radial (even "centripetal"), but the orientation of the vessel (and
> its
> engines and depicted reaction exhaust) is tangential.
This is a good point. In mathematical terms, the accelerating ship must
always be facing toward the principal unit normal vector*, except when
acceleration is parallel to velocity.
That is, _any_ maneuver (except straight-line acceleration/deceleration)
will cause the ship to _not_ face in the direction of motion.
.
* For a vector-valued curve, r(t), the unit tangent vector T is
(dr/dt)/|dr/dt|. The principle unit normal vector N, which always
points "into" turns, is (dT/dt)/|dT/dt|. Clearly, N is undefined when
dT/dt = 0, i.e., when the unit tangent vector is constant, which happens
when 1. the ship is not accelerating or 2. the ship is accelerating but
the acceleration is parallel to the velocity.
max
Paul Dietz wrote:
>
> max wrote:
>
> > Oh really? I doubt that computers will ever surpass the human brain. To do
> > so would be to.. go against nature's fundamental principles of natural intelligence.
>
> "Nature's fundamental principles of natural intelligence?"
> There were some things machines were not meant to do, eh?
>
> The 30 year claim comes from estimating the amount of processing
> going on in the brain (this is where the assumptions come
> in -- it's not known for sure how much processing is occuring
> at the subcellular level). There are about 10^14 synapses
> in the brain, each firing at about 10 s^-1, for about 10^15
> basic operations per second. If memory is stored in synapses,
> say ten bits per synapse, this is also about 10^15 bits.
>
> So, peta-op computers, peta-bit memories, and peta-bps
> communications to connect them (but much of that is local;
> long range communication in the brain is in the hundreds
> of gigabps, over axons that are less numerous than synapses).
> Today's supercomputers are in the tera-op range of computation,
> and tens or hundreds of gigabits of RAM. Estimate that
> computer attributes are improving by roughly a factor of
> 100 each decade. 10^15 bits of RAM might cost $400 M today,
component densities in IC's has slowed down due to physical limits on "wire" width?
Of course, IBM's answer to this is copper pathways, instead of aluminum.
So what I'm saying is that perhaps the IC industry is going to run into similar
roadblocks. Then there are limits to the size of a microchip, because of heat
dissipation and of course difficulty in manufacturing large chips. (dopant diffusion
problems?)
>
> AI has failed so far in part because the machines just aren't
> powerful enough, by many orders of magnitude. But thinking
> that this will remain true when computers do acquire, then
> exceed, the raw processing power of the brain is, I think,
> something of a head-in-the-sands attitude. OK you win. You know, Hal took up a good sized room in 2001 Space Odyssey.
This could mean that "small" AI spaceships won't be so small.
> Exponential improvement means the time of parity will arrive much sooner
> than you might think.
> You can rightly point out that this machine will have to
> be programmed. I look to the neuroscience community for
> inspiration there. Knowledge of the function of the brain
> is doubling every ten years. Most of what will be known
> about the brain 30 years hence is unknown today. You mean that neuroscience will somehow merge with programming? An interesting
possibility, but it will take a lot of talent, from the programmers. Is practical neuron
simulation software available today?
>
> NASA and various universities have a petaflop supercomputer
> project, btw.
Cool. Where can I find out more about this?
Max N.
Paul Dietz
max wrote:
> Good argument so far, but: isn't it true that the progress in increasing
> component densities in IC's has slowed down due to physical limits on "wire" width?
The problems with wires limit transmission of signals over
long distances on a chip. One way around this is to make computation
on the chip more local, say by exploiting parallelism. Fortunately,
neural computation appears to be very local and parallel.
> So what I'm saying is that perhaps the IC industry is going to run into similar
> roadblocks. Then there are limits to the size of a microchip, because of heat
> dissipation and of course difficulty in manufacturing large chips. (dopant diffusion
> problems?)
A problem is that historically people have said we're
about to run into a fundamental limit and Moore's law is going
to stop. Each time, the limit has been evaded. Engineers
are very creative, there's huge incentive to find workarounds,
and the design space is large.
> OK you win. You know, Hal took up a good sized room in 2001 Space Odyssey.
> This could mean that "small" AI spaceships won't be so small.
Or it could mean we just have to wait a generation or two
in technology, until the machine *is* small.
> You mean that neuroscience will somehow merge with programming?
> An interesting possibility, but it will take a lot of talent,
> from the programmers. Is practical neuron simulation software
> available today?
It's an active research area today (computational neuroscience).
Systems such as Neural Simulation Language (NSL), NEURON and GENESIS
are allowing the modeling of groups of biological neurons, or
individual neurons at greater level of detail. Detailed simulation
of individual neurons is probably overkill for an AI, but should be
useful for figuring out how biological systems work.
I expect the flow of information to programmers to be abstractions
of the algorithms (taking that word loosely) used in the brain.
There are many computational neuroscience sites on the web; go
searching/surfing to get a flavor of current work.
About petaflops computing: http://www.aero.hq.nasa.gov/hpcc/petaflops/
Some relevant links on the growth of computer power
vs. the power of the brain:
http://www.merkle.com/brainLimits.html
http://www.hedweb.com/nickb/superintelligence.htm
http://www.kurzweiltech.com/noframes/l1192.htm
http://kit.cat.nyu.edu/Articles/Jack/connect.html
http://www.charlesriver.com/books/bhchap6.html
(the estimates here can be an order of magnitude or two
above the one I gave; these estimates are necessarily rough
at this time.)
An interesting military research effort from DARPA is
described at
http://ito.darpa.mil/Summaries97/F309_0.html
This program's goal is to "demonstrate a computer system
that exhibits the emergent behavior associated with
human-like capabilities. These capabilities include sensor
fusion, mission planning, real time learning/generalization,
control, and innovation in novel battlefield situations.
The Artificial Nervous System [ANS] will provide artificial
pilots for multiple military platforms, each having multiple
functionality, in the early part of the twenty first century."
And let's not forget Vinge's Singularity paper:
http://www.nytimes.com/library/cyber/surf/1120surf-vinge.html
Paul
Matthew Debell
John Schilling (schi...@spock.usc.edu) wrote:
: I'll see if I can dig up the original post, but IIRC I assumed a baseline
: "space cruiser" massing a thousand tons, equipped with a passive sensor
: comparable to a two-meter astronomical telescope (note that two-meter
: telescopes fit neatly into ten-ton spysats; plenty of room on a cruiser).
Using the equivalent of a two-meter astronomical telescope to keep an
eye out for interlopers, what could one expect to see? How far away could
a ship of, say, a thousand tons be spotted? And how fast would you assume
you could scan a given arc of space for targets?
--
Matthew DeBell deb...@gusun.georgetown.edu
Bill Dugan
On Sat, 27 Dec 1997 22:38:16 +0200, Grosberg
<elra...@netvision.net.il> wrote:
snip
>How do FX people plan ship movement in, say, B5? As someone who uses
>3d CGI I can say that it's not easy to create realistic space flight
>unless you have some simulator that has newtonian mechanics programmed
>into it, and could transfer the data to the 3d program.
I don't know how B5 does it.
The data transfer from a simulator ought to be possible, if the 3d
program provides some way to import the flight path. I still suspect
that the simulator would end up being something like a space war game,
with things like weapons effects programmed in as well as Newtonian
motion.
Samuel
John Schilling wrote:
>
> Samuel <davi...@pilot.msu.edu> writes:
<Snip previous statements>
> > In space warfare silence, invisibility and PASSIVE sensors would be the
> >rule...
>
> Passive sensors, yes. Invisibility, not likely. The energies required
> to move a spacecraft across astronomical distances are, well, astronomical,
> and there is not much of a background to hide them in. Against an enemy
> with even modest passive sensors, it is not possible for a spacecraft
> to remain hidden unless it remains motionless and inactive - the last
> time I worked the numbers, even minor tactical maneuvers would have to
> be planned and executed over the course of a week or so, in order to
> avoid detection.
>
> One can imagine rare, contrived scenarios where 'stealth' spaceships
> lurking in ambush might prove useful, but for the most part mobility
> is likely to be more valuable. A static force, as any space fleet
> attempting to remain invisible must be, can almost invariably be
> defeated in detail by a mobile adversary capable of concentrating
> its forces at will.
>
I would say it depends on how you do it...
I imagine a main ship as command and control that would contain the
people directing the battle. This ship would remain silent, possibly
"drifting" in or using something like a magnetic sail (Question: could
this be detected? I'm not sure.)This ship would direct "robot" ships or
missiles which would do the actual fighting.
The main ship could stay well away from the major battle and conduct
the battle, but not too far; communication lag could be a real problem.
If the ship was detected it might be in a better position to defend
itself than if it were "in the fray", so to speak.
It's not perfect but it could give the people directing the battle a
fighting chance...
Larrison
schi...@spock.usc.edu (John Schilling) writes:
>Passive sensors, yes. Invisibility, not likely. The energies
>required to move a spacecraft across astronomical distances are,
>well, astronomical, and there is not much of a background to hide
>them in. Against an enemy with even modest passive sensors, it is
>not possible for a spacecraft to remain hidden unless it remains
>motionless and inactive - the last time I worked the numbers, even
>minor tactical maneuvers would have to be planned and executed over
>the course of a week or so, in order to avoid detection.
Hmm ... In general I agree with this, but you can certainly come
up with some interesting "what-if" scenarios. Against an enemy with
modest passive sensors (roughly today's capabilities, let us say), I
can come up with several ways to avoid active detection, most of
which are variants upon stealth techniques. Given a good initial
velocity, and some reasonable time scales (weeks), you can have a
spacecraft with high relative velocity -- but you can't accelerate or
maneuver it. That's good for reconnaissance or intelligence
gathering, but once you fire up the engines, you light up the
detectors as well. Particularly, if you light up that jippy-whamo
space drive and start accelerating at 1 G for several hours. (You've
got to dump that waste heat somewhere...)
There are some interesting variants, though. Given a large enough
initial mass, you can dump some heat from that drive into a thermal
battery, such as a phase change material (paraffin or ice come to
mind) to reduce your signature. But you are limited to your initial
mass. If you are close enough to a large body, you might do a
aerodynamic or gravitational slingshot -- but that's good for maybe a
few 1000's of meters/ sec at *best*. If you're in a planet with a
significant magnetic field, there are tethers, which might offer some
interesting ways to change momentum or pick up energy, or just use
the tether to get some momentum transfer for change in velocity. For
on-board propulsion systems, about the only one I can think of is to
use a mass driver (Isp ~ 1000 sec, from O'Neil's work) which I think
can be operated in a reduced signature mode.
>One can imagine rare, contrived scenarios where 'stealth' spaceships
>lurking in ambush might prove useful, but for the most part mobility
>is likely to be more valuable. A static force, as any space fleet
>attempting to remain invisible must be, can almost invariably be
>defeated in detail by a mobile adversary capable of concentrating
>its forces at will.
However, there are scenarios, which I can devise where using
"stealth" spaceships might be really useful. These include recon and
intelligence gathering, as before; covert insertion of forces (I'm
not talking about planetary surfaces, but just inserting them into
the opponent's vicinity before the balloon goes up); covert insertion
of mines or other area denial weapons (spreading random clouds of
non-metallic, non-reflective space junk might be useful); or the
insertion of specialized forces into a region of future conflict to
gain some type of operational advantage in a more generalized
conflict.
As you point out, a static force will almost invariably be
defeated in detail by a mobile adversary -- but I think the real
usefulness of a "stealthed" spacecraft would be to prepare the field
to give one mobile force an advantage over the other. Such as sowing
fields of mines/ space junk sufficient to reduce the maneuverability/
operational effectiveness of one force, when attacked by another.
--------------------------------------------------------------------
Wales Larrison Space Technology Investor
aRJay
In article <34ab34e9...@nntp.ix.netcom.com>, Bill Dugan
<wkd...@ix.netcom.com> wrote
>>their intuitions rewired?
>
>non-viscous Space War to use for planning the ship motion.
OK this is slightly off-topic but what is Space War and where would I
get it? (Oh yes and how much?)
--
aRJay
Bill Dugan
On Sun, 28 Dec 1997 09:04:53 +0000, aRJay <aR...@escore.demon.co.uk>
wrote:
>OK this is slightly off-topic but what is Space War and where would I
>get it? (Oh yes and how much?)
Space War was one of the original space combat simulation games. I
don't know of anyone who's selling it today.
Bill Dugan
On 27 Dec 1997 14:11:32 -0800, schi...@spock.usc.edu (John Schilling)
wrote:
>I'll see if I can dig up the original post, but IIRC I assumed a baseline
>"space cruiser" massing a thousand tons, equipped with a passive sensor
>comparable to a two-meter astronomical telescope (note that two-meter
>telescopes fit neatly into ten-ton spysats; plenty of room on a cruiser).
>Propulsion was by a doubletalk drive capable of any performance desired
>save that it had to comply with Newtonian physics, and that no more than
>99% of the drive energy could be shielded or redirected from the enemy's
>sensors. I considered both major and minor tactical maneuvers, with
>"major" cosntituting a net change in position equal to the initial
>engagement range and "minor" one percent of that.
Unless you already know approximately where to look, those sensors
would need a much wider field of view than current astronomical
telescopes. That might have some impact on their performance.
Anthony Buckland
schi...@spock.usc.edu (John Schilling) writes: > Paul Dietz <di...@interaccess.com> writes:
>
> >John Schilling wrote:
>
> >> with even modest passive sensors, it is not possible for a spacecraft
>
> More generally, substitute "unable to respond to enemy actions or otherwise
> exploit any advantage you might have gained by remaining hidden in the first
> place". Unless your initial trajectory just happens to put you where you
If you're in anything resembling the vicinity of the enemy, and are away from
objectives (such as someone's home planet or colony) known in advance to be
valuable, surely it's because you decided he was going to be there. How?
From your earlier knowledge of his position, acceleration and course. If
he has the same capabilities, he at that time knew the same things about
you. So unless jamming or something else permitted one of you an extended
period under power to alter acceleration and course without being detected,
each of you was able to predict, continuously, that the other would arrive
in the battle zone at a certain time, position and velocity. If one of
you screwed up, no meeting. So now you've arrived. If your detection
techniques were _really_ good, you have enough information to start laying
down a barrage as in WWII depth charge attacks. Otherwise, there's this
waiting game in which whoever takes first shot lights themselves up, again
very much like the destroyer-submarine lurking problem.
Dave O'Neill
Elite III has a nice combat system with a nice way of showing the effect
of gravity wells and acceleration and direction vectors... Of course it
means it's almost impossible to catch up with anyother ship without
autopilot...
Dave O'Neill
A little of subject as it's written SF, but Peter Hamilton uses
un-manned combat 'waps' for most of the conflict in his SF books...
simple semi-intelligent explosive ships...
I concur with those above... you don't need to be that clever to fight
in space, just accurate...
Dave O'Neill
Just in terms of what we are looking for from artificial intelligence
when it comes to space battles...
Well, I'd like clarification? We use a large number of fairly
intelligent un-manned weapons already and they get better every year...
missiles, torpedos and the new generation of UMCW the US are building.
Space makes it slightly easier surely, you waste tonnes on life support
plus you are severly limited on the accelerations you can impose on the
vehicle.
And also, just what is your pilot in the 'space fighter' doing... most
of the orbital mechanics with flying is way way beyond a pilot
anyway... build cheap flying bombs designed to take out enemy targets
asap...
The battles then come down to a matter of who has the most not the
brightest...
Erik Max Francis
Dave O'Neill wrote:
> Elite III has a nice combat system with a nice way of showing the
> effect
> of gravity wells and acceleration and direction vectors... Of course
> it
> means it's almost impossible to catch up with anyother ship without
> autopilot...
There's an Elite III?
Alastair Ward
In article <34A546FB...@interaccess.com>, Paul Dietz (di...@interaccess.com) writes:
>max wrote:
>
>> Oh really? I doubt that computers will ever surpass the human brain. To do
>> so would be to.. go against nature's fundamental principles of natural intelligence.
>AI has failed so far in part because the machines just aren't
>powerful enough, by many orders of magnitude. But thinking
>that this will remain true when computers do acquire, then
>exceed, the raw processing power of the brain is, I think,
>something of a head-in-the-sands attitude. Exponential
>improvement means the time of parity will arrive much sooner
>than you might think.
I would go along with that. There is quite powerful pressure to
develop machine recognition diagnosis in Medicine. For example
the microscope examination of cervical smears in the early diagnosis
of cervical cancer is an important screening technique which places a
great deal of strain on skilled human resources. And this is just one
example of many. As the likelihood of major wars receeds and dies
away I think there will be ever increasing emphasis on medical
applications of Science. Once really big money is made available I
would expect some real progress in these important peace time
applications involving AI. I see no reason to suppose that computers
will not surpass the human brain.
Al.
Al.
Kat
Er, WRONG. Surface ships and cars SHOULD be banking in the same
direction as planes do, if they could. The fact that cars CANNOT bank
causes them to move in the opposite direction, if they could bank,
this movement would be countered, this is WHY you bank. Take a look
at modern highways, where they could, they have the turns banked. Look
at race tracks, the turns are banked, in the SAME direction that a
plane would bank were it making the turn.
In <680luq$k0u$1...@its1.ocs.lsu.edu>, k...@bit.csc.lsu.edu (Isaac Kuo)
writes:
>Actually, the ideas of banking aren't intuitive either. They are
>only intuitive because of experience with airplane flight. If one
>were only experienced with ship or car motion, it would be intuitive
>to bank vessels in the opposite direction!
Leonard Erickson
max <ma...@erols.com> writes:
> Then there are limits to the size of a microchip, because of heat
> dissipation and of course difficulty in manufacturing large chips.
> (dopant diffusion problems?)
No, it's because even the *best* silicon wafer substrates have defects.
And the defects are "X defects per unit area". Therefore, the larger
the chip (actually the *die*), the more likely it is to include a
crystal defect (and thus not work). Thus, the bigger the chip, the
lower the yield (for a given defect density).
Since we *aren't* going to get *perfect* wafers any time soon, the
tradeoff is between size and yield.
Also, the bigger the chip, the fewer you get from a given sized wafer,
due to edge effects (the wafers are circular for various *good*
reasons)
--
Leonard Erickson (aka Shadow)
sha...@krypton.rain.com <--preferred
leo...@qiclab.scn.rain.com <--last resort
Leonard Erickson
Samuel <davi...@pilot.msu.edu> writes:
> John Schilling wrote:
>>
>> Samuel <davi...@pilot.msu.edu> writes:
>
> <Snip previous statements>
>
>> > In space warfare silence, invisibility and PASSIVE sensors would be the
>> >rule...
>>
>> Passive sensors, yes. Invisibility, not likely. The energies required
>> to move a spacecraft across astronomical distances are, well, astronomical,
>> and there is not much of a background to hide them in. Against an enemy
>> with even modest passive sensors, it is not possible for a spacecraft
>> to remain hidden unless it remains motionless and inactive - the last
>> time I worked the numbers, even minor tactical maneuvers would have to
>> be planned and executed over the course of a week or so, in order to
>> avoid detection.
>>
>> One can imagine rare, contrived scenarios where 'stealth' spaceships
>> lurking in ambush might prove useful, but for the most part mobility
>> is likely to be more valuable. A static force, as any space fleet
>> attempting to remain invisible must be, can almost invariably be
>> defeated in detail by a mobile adversary capable of concentrating
>> its forces at will.
>>
>
> I would say it depends on how you do it...
>
> I imagine a main ship as command and control that would contain the
> people directing the battle. This ship would remain silent, possibly
> "drifting" in or using something like a magnetic sail (Question: could
> this be detected? I'm not sure.)This ship would direct "robot" ships or
> missiles which would do the actual fighting.
Still a problem. The ship is at 300K as that's the temperature that
humans work at. And that means that the ship's hull will stabilize at
around 300K. Cosmic background is *3K*. And energy vs temp is a fourth
power law. Thus the ship will be 100^4 = 10^8 = *ten million* times
brighter than the sky.
And there's no easy way around this. Insulation does *not* reduce the
final temp of the hull, it just increases the time it takes to reach
it. And if you insulate, you are effectively *raising* the internal
temp, as the human bodies are providing 100 watts each of heats, as
well as all the electronics, etc. Remember, the *only* way to get rid
of heat is to *radiate* it, there's no air to conduct or convect it
away.
So you either have *huge* radiators (to reduce the temp by increasing
the area available for getting rid of the heat) or you have a hot (and
thus "bright") hull. The big radiators cut down on your IR signature
but *increase* your radar signature.
> The main ship could stay well away from the major battle and conduct
> the battle, but not too far; communication lag could be a real problem.
> If the ship was detected it might be in a better position to defend
> itself than if it were "in the fray", so to speak.
Communications *also* renders the ship visible. Radio transmissions
spread even with the best antenna. And even laser comm will spread a
*lot* over the distances involved.
Stealth in open space is not going to be workable except in *highly*
unusual situations.
Matthew Debell
Matthew Debell (deb...@gusun.georgetown.edu) wrote:
: John Schilling (schi...@spock.usc.edu) wrote:
: : I'll see if I can dig up the original post, but IIRC I assumed a baseline
: : "space cruiser" massing a thousand tons, equipped with a passive sensor
: : comparable to a two-meter astronomical telescope (note that two-meter
: : telescopes fit neatly into ten-ton spysats; plenty of room on a cruiser).
: Using the equivalent of a two-meter astronomical telescope to keep an
: eye out for interlopers, what could one expect to see? How far away could
: a ship of, say, a thousand tons be spotted? And how fast would you assume
: you could scan a given arc of space for targets?
A bit of reading reveals part of the answer to my own question. Apparently
the Hubble Space Telescope is a 2.4 meter apparatus that can resolve a
tenth of an arcsecond. If I figure correctly, that means it can create
images with a resolution of about a meter at distances of several
hundred kilometers. (These are very loose numbers; I didn't actually do
the math.) This is not very useful for long-range detection of targets.
So if my numbers are accurate within an order of magnitude, spying a ship
through the telescope is not going to be used as the means of detection.
(Also, as someone mentioned in another post, the field of view is very small,
so you need to have some idea of where to start looking. This makes the
problem even worse.)
It is much more likely that a telescope would detect ships by simply noticing
the light they emit or reflect, rather than resolving an image of them.
Since ships are small (relative to celestial bodies) and can be painted to
have a low albedo, they're probably not apt to reflect a lot of light.
However, if they run on something like a fusion drive and are fast, then
they'll glow like multi-gigawatt light bulbs. So the question becomes,
at what range could a two-meter telescope detect the light from a multi-
gigawatt visual radiation source? (Or, more generally, how faint an object
can one detect with a two meter telescope?)
--
Matthew DeBell deb...@gusun.georgetown.edu
Christian Weisgerber
In article <34A698...@virgin.net>, Dave O'Neill
<david.o'nei...@virgin.net> wrote:
> A little of subject as it's written SF, but Peter Hamilton uses
> un-manned combat 'waps' for most of the conflict in his SF books...
wasps
> simple semi-intelligent explosive ships...
At least in _The Reality Dysfunction_ (and sequels, I assume). I thought
the earlier novels were all Earth based... but then I haven't read them
yet.
Anyway, to elaborate a bit on the concept: combat wasps are robotic
interceptor drones that approach the target and then fragment into a
plethora of sub-munitions: unguided and self-guiding kinetic kill
devices; nuclear warheads, sometimes optimized for neutron output, EMP,
etc; nuclear-pumped x-ray and gamma lasers; sub-sub-munitions;
antimatter; etc. Probably every space combat weapon ever discussed in
this group.
Since combat wasps are unmanned they can effectively use any
acceleration the drive technology can provide. I seem to recall a figure
of 40g being mentioned in one battle scene. Both sides use combat wasps,
so in practice these nasties are mostly concerned with eliminating each
other. Altogether, I found the idea of combat wasps quite plausible.
Another nice weapon from the same book:
"Kinetic harpoons were the Confederation Navy's standard tactical
(non-radioactive) planetary surface assault weapon. A solid splinter
of toughened, heat-resistant composite, half a metre long, needle
sharp, guided by a cruciform tail, steered by a processor with a
preprogrammed flight vector. They carried no explosives, no energy
charge; they destroyed their target through speed alone."
You "drop" a charge of these from orbit--boom! In the example in the
book, a small ship unloads five thousand harpoons at an altitude of
1200km to obliterate an area of 21 km^2 in a single support strike for
the ground troops. Ouch.
--
Christian "naddy" Weisgerber na...@mips.rhein-neckar.de
See another pointless homepage at <URL:http://home.pages.de/~naddy/>.
Wayne Throop
: Erik Max Francis <m...@alcyone.com>
: In mathematical terms, the accelerating ship must always be facing
: toward the principal unit normal vector*, except when acceleration is
: parallel to velocity.
Actually I think that's not quite generally true: it's only true if the
ship has constant absolute-value-of-velocity on that trajectory. If the
course is curved, the ship can't point at the tangent vector as is
portrayed, but it can point between the tangent vector and the normal
vector; that means it's speeding up. Very small nit. Oh, and we're
presuming thrust is along the axis of portrayed exhaust
(or streamlining in a whitestar).
: That is, _any_ maneuver (except straight-line
: acceleration/deceleration) will cause the ship to _not_ face in the
: direction of motion.
Right, that's the key point.
Larry Caldwell
In article <6830gs$m7u$1...@its1.ocs.lsu.edu>,
k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
> Tactical maneuvers in space combat would thus be less rich than
> those in aerial combat.
Well ... certainly less close quarters dogfighting. The party with the
greater delta V will always have their preferred range and position in
a space battle, while the party with the superior ordnance will be able
to assure that the preferred range and position is somewhere else. :)
However, long term strategies, with diffuse kinetic weapons (birdshot),
foil, fog, lasers, missles, mines, flak, shaped charges and such should
add the variety back in. Just the fact that if you throw something it
keeps on going forever can be a tactical advantage if you can lead your
opponent into the killing zone.
If you can pick your battles in a particular time and place, you can
spend a week bracketing the whole battle zone except for a few
precalculated safe positions. When the time comes, you just play
wounded duck and cut the sucker to pieces.
-- Larry
Nyrath the nearly wise
Thus spoke Isaac Kuo <k...@bit.csc.lsu.edu>:
> [about Starfuries]
>>: They've got wings!
>>They've got support struts, which are thicker in the direction
>>of greatests stress from the engines, as indeed they need to be.
> They look like wings.
> Anyway, support struts wouldn't need to be "solid". As is depicted
> in many other B5 Earthforce vessels, a strutted structure would
> save weight for equivalent strenth. Even better, the engines could
> have been placed right next to the hull, resulting in even more
> saved weight.
Well, I was under the impression that B5 Starfuries
had the struts in an attempt to get the massive attitude
jets far from the ship's center of gravity in a bid
to increase their torque.
--
* A B S I T * I N V I D I A * V E R B O ** I D E M * S O N A N S *
+----------------------------------------------------------------------------+
| WINCHELL CHUNG http://www.clark.net/pub/nyrath/home.html |
| Nyrath the nearly wise nyr...@clark.net |
+---_---+---------------------[ SURREAL SAGE SEZ: ]--------------------------+
| /_\ | You take Zathras, Zathras die. You leave Zathras, Zathras die. |
| <(*)> | Either way, it is bad for Zathras. |
|/_/|\_\| |
| //|\\ | |
+///|\\\+--------------------------------------------------------------------+
John D. Gwinner
Al:
Alastair Ward <aw...@eildon.win-uk.net> wrote in article
<9...@eildon.win-uk.net>...
> As the likelihood of major wars receeds and dies
> away I think there will be ever increasing emphasis on medical
> applications of Science. Once really big money is made available I
> would expect some real progress in these important peace time
> applications involving AI. I see no reason to suppose that computers
> will not surpass the human brain.
I'm not sure why you link medical science to lessening of wars ... there
are many medical breakthroughs (reconstructive surgery which lead to
plastic surgery, for example) that have come out of war. Like most things,
unfortunately. (The US Economy got an incredible boost during WWII)
After having said that, I wouldn't mind a smaller Army and Air Force, and
more spending on a Space Navy!
But that's not what happens. Space research, specifically the budget for
NASA, typically competes with medical research (This conclusion from
watching a TV debate with some of the principals involved, but I can't
remember who); not DoD's budget.
== John ==
Isaac Kuo
In article <971228.213020...@krypton.rain.com>,
Leonard Erickson <sha...@krypton.rain.com> wrote:
>Samuel <davi...@pilot.msu.edu> writes:
>> I would say it depends on how you do it...
>> I imagine a main ship as command and control that would contain the
>> people directing the battle. This ship would remain silent, possibly
>> "drifting" in or using something like a magnetic sail (Question: could
>> this be detected? I'm not sure.)This ship would direct "robot" ships or
>> missiles which would do the actual fighting.
>Still a problem. The ship is at 300K as that's the temperature that
>humans work at. And that means that the ship's hull will stabilize at
>around 300K. Cosmic background is *3K*. And energy vs temp is a fourth
>power law. Thus the ship will be 100^4 = 10^8 = *ten million* times
>brighter than the sky.
No, the ship's outer hull need not be at around 300K, only the crew
compartment. The crew compartment needs to be insulated from the
outer hull, with just enough overall heat leakage (by passive design
and/or active pumping in one or both directions) at 300K to match
the heat generated by the humans (and displays).
>And there's no easy way around this. Insulation does *not* reduce the
>final temp of the hull, it just increases the time it takes to reach
>it. And if you insulate, you are effectively *raising* the internal
>temp, as the human bodies are providing 100 watts each of heats, as
>well as all the electronics, etc. Remember, the *only* way to get rid
>of heat is to *radiate* it, there's no air to conduct or convect it
>away.
100 watts per human is heat, not temperature. Radiate that amount
over a large enough outer hull surface area, and the equilibrium
temperature can be made arbitrarily close to 3K. Most of a
military spacecraft is going to be dominated by lots of equipment
that aren't in the crew compartment--especially the fuel tanks--so
it's already going to have a large outer hull surface area compared
to the number of humans. The crew compartment itself would most
likely be a small multi-person "coffin" surrounded by a couple
feet of radiation shielding (possibly emergency fuel tanks).
A potentially more serious problem is the heat absorbed from
sunlight (there's a _lot_ more of this than human generated heat in
our little neighborhood). Really, the best way to deal with the
heat from sunlight is to not absorb it in the first place. An
elongated shape with an angled mirror facing the sun (shading the
rest of the ship) will accomplish this, at the cost of being
extremely visible in a narrow cone in the direction the sunlight
is reflected.
Therefore, directed heat rejecters might as well reject heat in
the same direction as the reflected sunlight. The ship's already
going to be very visible in that direction.
BTW, the computers of a 3K design ship will almost certainly
be superconducting, and thus generate practically no heat at all.
>So you either have *huge* radiators (to reduce the temp by increasing
>the area available for getting rid of the heat) or you have a hot (and
>thus "bright") hull. The big radiators cut down on your IR signature
>but *increase* your radar signature.
The mirror needed to deflect sunlight is also a huge radar reflector.
This is a more inherent problem than dealing with heat generated
by humans.
>> The main ship could stay well away from the major battle and conduct
>> the battle, but not too far; communication lag could be a real problem.
>> If the ship was detected it might be in a better position to defend
>> itself than if it were "in the fray", so to speak.
>Communications *also* renders the ship visible. Radio transmissions
>spread even with the best antenna. And even laser comm will spread a
>*lot* over the distances involved.
Laser comm will spread a lot, but will still subtend a very small
angle. By using a small number of laser comm relays, practical
stealthy communications are quite plausible.
>Stealth in open space is not going to be workable except in *highly*
>unusual situations.
Stealth in open space would take advantage of the one most obvious
feature of open space--it's very big. No matter how sensitive one's
sensors are, space is so big it's still possible to be further away
than it's practical to scan reliably at (scanning requires applying
sensitive detectors over a larger volume). This is particularly
significant wrt sunlight--the sunlight problem gets minimal in the
outer solar system.
As long as one's weapon systems have a longer practical range than
the enemy's practical scanning range, then it's possible to employ
practical "stealth".
Anyway, in the near future, the relative insensitivity of our
sensors will ensure that the practical scanning range for stealthed
spacecraft will be pretty low. Such stealthed spacecraft would
be radar-stealthed and low albedo, but "shine" in infrared. In
the near future, ground based sensors will greatly outnumber
and outpower space based sensors--radar works through the
atmosphere while IR practically doesn't. The fact that these
ships would shine millions of times brighter than the background
in IR is not as relevant as the fact that they still don't shine
very brightly, so near future IR scanners will need to be relatively
close (compared to the distances of interplanetary space) to
scan for them.
--
_____ Isaac Kuo k...@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
__|_)o(_|__
/___________\ "Mari-san... Yokatta...
\=\)-----(/=/ ...Yokatta go-buji de..." - Karigari Hiroshi
Peter Kwangjun Suk
On Fri, 26 Dec 1997 11:24:38 PST, sha...@krypton.rain.com (Leonard
Erickson) wrote:
>You *can't* fly a spaceship like an airplane, simply because the
>dynamics involved are so different.
Actually, if you mounted an engine in the belly of the thing, pointing
"up" you could. You'd even have to pull a 90 degree bank to turn "to
the side." I could imagine that these things would be built for
hobbyists who want to "fly" around space for the thrill of it.
The old Atari 68000 PC had a game called "Elite" with space combat on
this model.
[snip]
>Things get even *more* counter-intuitive when you are making maneuvers
>while in close orbit. Then you get weird things like slowing down takes
>you farther out.
Don't you mean "farther in"?
--PKS
[s...@xpobox.com. remove the initial x to send me email]
Peter Kwangjun Suk
>>> with even modest passive sensors, it is not possible for a spacecraft
>>> to remain hidden unless it remains motionless and inactive - the last
>>> time I worked the numbers, even minor tactical maneuvers would have to
>>> be planned and executed over the course of a week or so, in order to
>>> avoid detection.
>More generally, substitute "unable to respond to enemy actions or otherwise
>exploit any advantage you might have gained by remaining hidden in the first
>place". Unless your initial trajectory just happens to put you where you
>need to be when you need to be there
Stealth in space combat would be a very useful offensive tool. There
seems to be an assumption in this group that it would be defensive in
nature. And come to think of it, I have never explicitly stated this
idea.
[snip]
>And playing with the assumptions, talking space fighters rather than
>space cruisers, giving the stealth guys 99.9% efficient drives, whatever,
>didn't actually change very much.
But something like the ability to restrict one's emissions to a 30-deg
cone, strategically oriented, might be very useful. One might take a
few weeks to execute a strategic manuver at a "fixed" target like a
planet or a space-station. Then one would blow one's cover at the
last moment, unloading a barrage of guided munitions targeted during
the stealthy approach, then power up the high-thrust low-efficiency
drives and run like hell.
It would be worth it to have such a capability, just to force your
enemy into sinking tons of resources into expensive detection systems.
Isaac Kuo
In article <VZ2p00O5...@teleport.com>,
>> Tactical maneuvers in space combat would thus be less rich than
>> those in aerial combat.
>Well ... certainly less close quarters dogfighting. The party with the
>greater delta V will always have their preferred range and position in
>a space battle, while the party with the superior ordnance will be able
>to assure that the preferred range and position is somewhere else. :)
On a tactical level, basically so. Of course, there's a question of
who has more delta-v to spare--an issue which is more complex than
in aerial combat, where you basically just need to make sure you
have more than "bingo" fuel (the amount needed to get back to base or
a tanker). With space maneuvering, "bingo" fuel is constantly
changing depending on your current relative velocity compared to a
friendly "carrier" or "tanker".
>However, long term strategies, with diffuse kinetic weapons (birdshot),
>foil, fog, lasers, missles, mines, flak, shaped charges and such should
>add the variety back in. Just the fact that if you throw something it
>keeps on going forever can be a tactical advantage if you can lead your
>opponent into the killing zone.
Yes indeed! The wild variety of possible weapons and countermeasures
make for complex interactions. The two most fascinating possible
weapons, IMO, are lasers and missiles. They are about as different
from each other as you can imagine, but it's quite plausible that
they'd be used in conjunction.
Lasers have very low time-to-target, and it's effective to concentrate
the laser fire of an entire fleet, but there are all sorts of
countermeasures possible. However, a single hit from the lightest of
physical munitions is enough to put a chink in a target's "laser
armor" enough to let the lasers finish that target off in seconds.
Missiles alone would be a slow way to attack multitudes of cheap
balloon decoys, and would also be relatively easier to intercept
(missiles with bee-bee sized "ship-killer" submunitions would
be easier to stop/dodge than missiles with flour-powder
"mirror-damager" submunitions).
Having two weapon systems work with each other like this suggests
many tactical puzzles. Most obvious is the question of fleet
design--should it be a mixed fleet of laser ships and missile
ships or a fleet of mixed armament ships? What ratios are ideal?
What tactics are appropriate for enemies with different ratios?
How do tactics change with scale (number/power of ships on either
side)? What are the best countermeasures against missile
attack--intercept with defensive missiles or defensive laser fire?
Then there are the issues in laser combat alone--if you can surround
the enemy, then you can spread laser fire to prevent the enemy
from using heat rejectors. This will effectively eliminate the
enemy's capability to sustain lasing (but the enemy can still
fire missiles). Even if neither side is surrounded and both
have effective "laser armor", lasing can still damage sensors.
There are also issues in missile combat alone--if a fleet's ships
are moving at the same velocity, a single enemy ship or missile
salvo can take all of them out simultaneously (even if they are
far apart from each other). However, in order to stay near enough
to each other to support each other in combat for an extended
period of time, they need to be moving at relatively the same velocity.
There's a trade off needed between high delta-v offensive missiles
and low delta-v defensive projectiles (probably nuclear tipped).
>If you can pick your battles in a particular time and place, you can
>spend a week bracketing the whole battle zone except for a few
>precalculated safe positions. When the time comes, you just play
>wounded duck and cut the sucker to pieces.
The lack of air resistance in space potentially allows quite massive
time-on-target attacks. For instance, a single tiny little "machine
gun" could fire an hour long burst of 6000 bullets, all timed to
intercept the target zone at once.
Peter Kwangjun Suk
On Sat, 27 Dec 1997 21:00:27 -0800, max <ma...@erols.com> wrote:
>This could mean that "small" AI spaceships won't be so small.
But in the context of space combat, you don't necessarily need
"genius" AI. Something that can be produced in large numbers that can
execute a simple but effective tactic would be enough. It wouldn't
matter that all the fighter pilots in a carrier battle group were
nobel laureates if you could launch enough guided missles at it.
(But it might make for a humorous little vignette.)
Peter Kwangjun Suk
>And there's no easy way around this. Insulation does *not* reduce the
>final temp of the hull, it just increases the time it takes to reach
>it. And if you insulate, you are effectively *raising* the internal
>temp, as the human bodies are providing 100 watts each of heats, as
>well as all the electronics, etc. Remember, the *only* way to get rid
>of heat is to *radiate* it, there's no air to conduct or convect it
>away.
>
>So you either have *huge* radiators (to reduce the temp by increasing
>the area available for getting rid of the heat) or you have a hot (and
>thus "bright") hull. The big radiators cut down on your IR signature
>but *increase* your radar signature.
Anti-radar stealth is well understood and *completely independent of
size*. We could build aircraft carrier size anti-radar "stealth"
ships right now, if naval brass could get used to the idea.
Peter Kwangjun Suk
On 29 Dec 1997 15:32:40 GMT, k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
>>Communications *also* renders the ship visible. Radio transmissions
>>spread even with the best antenna. And even laser comm will spread a
>>*lot* over the distances involved.
>
>Laser comm will spread a lot, but will still subtend a very small
>angle. By using a small number of laser comm relays, practical
>stealthy communications are quite plausible.
Also, you folks forget about time. Instead of continuous
communications with the mother ship, the autonomous semi-intelligent
submunitions could aim their highly sensitive comm receivers at the
mother ship at preset times. Passive detection can be made to be
highly sensitive. However, doing this simultaneously for broad swaths
of sky is quite another matter. So stealthed ships will have to be
"scanned" for. There will be no guarantee that you'll be looking at
the right place at the right time to see them.
In any case, the high precision and fast reaction times needed in this
sort of combat would make moment-by moment remote control of the
drones impractical. Humans and sophisticated AI would be in charge of
overall strategy, with faster, less versatile AI doing the close-in
dirty work.
This is somewhat reminiscent of naval combat in Nelson's time, when
admirals made contingency plans ahead of time, and signalled the fleet
as to which one to implement using flags.
Bill Dugan
On 29 Dec 1997 15:32:40 GMT, k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
snip
>A potentially more serious problem is the heat absorbed from
>sunlight (there's a _lot_ more of this than human generated heat in
>our little neighborhood). Really, the best way to deal with the
>heat from sunlight is to not absorb it in the first place. An
>elongated shape with an angled mirror facing the sun (shading the
>rest of the ship) will accomplish this, at the cost of being
>extremely visible in a narrow cone in the direction the sunlight
>is reflected.
Rather than trying to be totally undetectable, it might be easier to
pretend to be some random piece of debris. Cover your ship with a thin
layer of suitable material, and let it absorb and radiate like an
asteroid fragment.
Dave O'Neill
Erik Max Francis wrote:
> There's an Elite III?
>
Yep, similar to elite II but with Thargons added... :-)
Erik Max Francis
Leonard Erickson wrote:
> Still a problem. The ship is at 300K as that's the temperature that
> humans work at. And that means that the ship's hull will stabilize at
> around 300K. Cosmic background is *3K*. And energy vs temp is a fourth
> power law. Thus the ship will be 100^4 = 10^8 = *ten million* times
> brighter than the sky.
Well, these particular figures aren't very revealing, because just
because the inside temperature is 300 K doesn't mean the outside
temperature has to be the same. For instance, the Sun's photosphere is
at about 6000 K, but that doesn't mean that the surface of a solid Dyson
sphere has to be 6000 K!
The conservation law dictates that power in = power out, not that
temperature in = temperature out.
However, one point still holds, though: The hull's temperature, or at
least parts of it, must be much higher than the background temperature
(though interplanetary space is considerably warmer than the cosmic
background, but I don't have any figures in front of me), particularly
considering the heat must be dissipated by radiation, which is a lot
less efficient than other means.
> Communications *also* renders the ship visible. Radio transmissions
> spread even with the best antenna. And even laser comm will spread a
> *lot* over the distances involved.
But if the parties that might be listening in are not very close to the
intended recipient, it's really not a big problem.
Erik Max Francis
Dave O'Neill wrote:
Elite II was Frontier, right?
I'll have to go look for this now . . .
Wayne Throop
: Nyrath the nearly wise <nyr...@clark.net>
: Well, I was under the impression that B5 Starfuries had the struts in
: an attempt to get the massive attitude jets far from the ship's center
: of gravity in a bid to increase their torque.
That seems an implausible motive. First of all, it's also putting
the massive engine components away from the center of spin, making
it harder to spin, and increasing the stresses on the engines and
fuel feeds at fast spins. And second, even under modest auxiliary
thrust, the ship can (IIRC my botec correctly) spin fast enough to
completely, dangerously bugeye the human stuck on the nose of the thing.
Using the main engines as a source of spin torque is much overkill
(again, IIRC my botec correctly).
John Schilling
wkd...@ix.netcom.com (Bill Dugan) writes:
>On 27 Dec 1997 14:11:32 -0800, schi...@spock.usc.edu (John Schilling)
>wrote:
>>I'll see if I can dig up the original post, but IIRC I assumed a baseline
>>"space cruiser" massing a thousand tons, equipped with a passive sensor
>>comparable to a two-meter astronomical telescope (note that two-meter
>>telescopes fit neatly into ten-ton spysats; plenty of room on a cruiser).
>>Propulsion was by a doubletalk drive capable of any performance desired
>>save that it had to comply with Newtonian physics, and that no more than
>>99% of the drive energy could be shielded or redirected from the enemy's
>>sensors. I considered both major and minor tactical maneuvers, with
>>"major" cosntituting a net change in position equal to the initial
>>engagement range and "minor" one percent of that.
>Unless you already know approximately where to look, those sensors
>would need a much wider field of view than current astronomical
>telescopes. That might have some impact on their performance.
Well, it would take some design changes to be sure. Larger detector
arrays, less depth of focus, faster transit rate, for starters. None
of this is likely to limit the overall performance - astronomical
telescopes have very narrow fields of view because astronomers are
very rarely interested in looking at more than one thing at a time,
not for fundamental technical reasons. The added capability will
cost a bit more, is all.
Out of curiosity, does anyone here have any specifications on
actual telescopes built specifically for sky mapping or similar
applications requiring large-area searches?
--
*John Schilling * "You can have Peace, *
*Member:AIAA,NRA,ACLU,SAS,LP * or you can have Freedom. *
*University of Southern California * Don't ever count on having both *
*Aerospace Engineering Department * at the same time." *
*schi...@spock.usc.edu * - Robert A. Heinlein *
*(213)-740-5311 or 747-2527 * Finger for PGP public key *
John Schilling
Anthony Buckland <buck...@direct.ca> writes:
>schi...@spock.usc.edu (John Schilling) writes: > Paul Dietz <di...@interaccess.com> writes:
>>
>> >John Schilling wrote:
>>
>> >> Against an enemy
>> >> with even modest passive sensors, it is not possible for a spacecraft
>> >> to remain hidden unless it remains motionless and inactive...
>>
>> More generally, substitute "unable to respond to enemy actions or otherwise
>> exploit any advantage you might have gained by remaining hidden in the first
>> place". Unless your initial trajectory just happens to put you where you
>> need to be when you need to be there...
>
> If you're in anything resembling the vicinity of the enemy, and are away
> from objectives (such as someone's home planet or colony) known in advance
> to be valuable, surely it's because you decided he was going to be there.
He may not have concurred in this decision, and may decline to show up.
>How? From your earlier knowledge of his position, acceleration and course.
If he's accelerating, you don't *need* to fall back on any earlier knowledge.
You can watch him in real time, modulo a lightspeed delay. And he can see
you as soon as you accelerate yourself, which you will need to do in order
to make use of the knowledge you gained by watching him.
> If he has the same capabilities, he at that time knew the same things about
> you. So unless jamming or something else permitted one of you an extended
> period under power to alter acceleration and course without being detected,
> each of you was able to predict, continuously, that the other would arrive
> in the battle zone at a certain time, position and velocity. If one of
> you screwed up, no meeting.
"Screwed up"?
You have, in your own hypothetical scenario, sent your forces out to some
volume of space devoid of any valuable objectives, and you consider the
enemy's failure to arrive on your terms, "screwing up"?
If he headed for such a region in the first place, it was a feint. As
soon as you complete your intercept burn, he'll change course and head
for someplace valuable, along a completely different trajectory than
you expected. And you can watch helplessly as you lie in ambush at
the wrong place, or blow your cover, again, as you try to intercept.
> So now you've arrived. If your detection techniques were _really_ good,
> you have enough information to start laying down a barrage as in WWII
> depth charge attacks. Otherwise, there's this waiting game in which
> whoever takes first shot lights themselves up, again very much like the
> destroyer-submarine lurking problem.
Only if *both* parties decide to play that game. If *either* side decides
to fight a battle of maneuver, the other side has to either follow suit and
reveal itself, or be left out of the fight altogether. Which means any
effort they made to achieve stealth in the first place, whether in terms
of ship design or strategic or tactical deployment, is wasted at best and
actively counterproductive at worst. The winning strategy is to design
and deploy for a battle of maneuver.
Your WWII submarine analogy is rather appropriate. Do, however, consider
that submarines in WWII were useful primarily for reconaissance and for
attacks on unescorted merchant shipping. Useful auxiliary tasks to be
sure, and analogous roles may be found for stealthed space warships,
but against conventional (surface) naval forces, submarines were useless
except by blind luck, and the navies which sent their subs out to do
battle with enemy warships (notably the IJN), failed miserably.
Submarines did not become effective general-purpose warships until nuclear
power allowed them to maneuver at speeds comparable to surface vessels
while still remaining reasonably stealthy. Which is a bit easier to
manage when you've got 10^17 tons of water to hide in, and fairly
modest propulsion requirements.
Samuel
Leonard Erickson wrote:
>
>
> Still a problem. The ship is at 300K as that's the temperature that
> humans work at. And that means that the ship's hull will stabilize at
> around 300K. Cosmic background is *3K*. And energy vs temp is a fourth
> power law. Thus the ship will be 100^4 = 10^8 = *ten million* times
> brighter than the sky.
>
> And there's no easy way around this. Insulation does *not* reduce the
> final temp of the hull, it just increases the time it takes to reach
> it. And if you insulate, you are effectively *raising* the internal
> temp, as the human bodies are providing 100 watts each of heats, as
> well as all the electronics, etc. Remember, the *only* way to get rid
> of heat is to *radiate* it, there's no air to conduct or convect it
Good points here; I had forgotten the problems with heat...
>
> Communications *also* renders the ship visible. Radio transmissions
> spread even with the best antenna. And even laser comm will spread a
> *lot* over the distances involved.
>
Message lasers could be used rather than radios. There is some spread
but otherwise it could be effective.
Paul Dietz
Bill Dugan wrote:
> Rather than trying to be totally undetectable, it might be easier to
> pretend to be some random piece of debris. Cover your ship with a thin
> layer of suitable material, and let it absorb and radiate like an
> asteroid fragment.
And, let's not forget decoys. Very low mass objects can be
made to have substantial IR signatures (you'd need to counter
light pressure to avoid giving away your mass, but a small
cold gas thruster could do that for a while.) This begins
to look like the ballistic missile defense problem.
Active measures could discriminate among decoys (neutral beams,
for example) but that would give away the position of the
beam generators.
Paul
Paul Dietz
John Schilling wrote:
> Out of curiosity, does anyone here have any specifications on
> actual telescopes built specifically for sky mapping or similar
> applications requiring large-area searches?
These are typically Schmidt-type telescopes. Because they
have a spherical mirror, the image remains in focus over
large angles. Baker-Nunn cameras also have very
wide fields of view. The latter have speeds as low as F/0.6,
if I recall correctly.
You might try checking out the Amateur Sky Survey (TASS)
web page; they're using time delay integration CCDs behind
ordinary 35mm camera lenses.
Large field of view does increase the background noise
in each pixel, assuming a constant aperture and detector
size, because each pixel is covering a larger solid
angle. In space, the background comes from stars and the
zodiacal light (especially in the IR). Rapidly moving
targets may be harder to see, because their signal is
smeared over more pixels.
See the Spacewatch home page and the Minor Planets Center
home page for links.
Paul
Isaac Kuo
In article <6892bf$s84$1...@spock.usc.edu>,
John Schilling <schi...@spock.usc.edu> wrote:
>wkd...@ix.netcom.com (Bill Dugan) writes:
>>Unless you already know approximately where to look, those sensors
>>would need a much wider field of view than current astronomical
>>telescopes. That might have some impact on their performance.
>Well, it would take some design changes to be sure. Larger detector
>arrays, less depth of focus, faster transit rate, for starters. None
>of this is likely to limit the overall performance - astronomical
>telescopes have very narrow fields of view because astronomers are
>very rarely interested in looking at more than one thing at a time,
>not for fundamental technical reasons. The added capability will
>cost a bit more, is all.
With a spherical mirror, a relatively large field of view through
a single aperture is possible, but there's a limit to how much
bigger you can make the detector array before it negatively affects
performance--the array itself blocks the mirror. Beyond that you
need multiple telescopes to cover a wider angle.
Either way, the added capability will cost proportionately more
because most of the cost is the sensitive detector array. If
you want to increase the field of view while maintaining the
same sensitivity and resolution, you'll have to increase the
number of elements in that array proportionately. Sharing a
single mirror for a relatively wide field of view helps out
in keeping it relatively more compact and lighter, though.
Cost will be a significant issue, though, in a military setting
because each array is quite vulnerable to blinding. Because
the spherical mirror requires a lens or other element to correct
its focus--but this focus isn't perfect--a laser or nuclear
explosion could blind an entire array, and potentially damage a
wide enough swath to practically require replacing the entire array.
A military vessel would probably have many spare arrays which could
be swapped in automatically. The smaller the array being used, the
lower this cost in replacements will be.
(A fast transit rate won't increase scanning capability much beyond
a certain point, because a faster transit rate proportionately
reduces the sensitivity of the detectors.)
Isaac Kuo
In article <34A83F28...@interaccess.com>,
>> Rather than trying to be totally undetectable, it might be easier to
>> pretend to be some random piece of debris. Cover your ship with a thin
>> layer of suitable material, and let it absorb and radiate like an
>> asteroid fragment.
The problem is that there aren't that many random pieces of debris
around, and they'll probably all be charted. It's kind of like a
naval vessel trying to pretend to be a random island. Not very
convincing!
>And, let's not forget decoys. Very low mass objects can be
>made to have substantial IR signatures (you'd need to counter
>light pressure to avoid giving away your mass, but a small
>cold gas thruster could do that for a while.) This begins
>to look like the ballistic missile defense problem.
Considering BMD is an example of space combat, it's not surprising.
Anyway, the effects of light pressure are low enough that I don't
think they need be worried about much--and the most effective way
to deal with it if you absolutely had to is to put your stealthy
thrusters on the _real_ ships. You want to keep the decoys as
light and simple as possible.
>Active measures could discriminate among decoys (neutral beams,
>for example) but that would give away the position of the
>beam generators.
Leonard Erickson
deb...@gusun.georgetown.edu (Matthew Debell ) writes:
> It is much more likely that a telescope would detect ships by simply noticing
> the light they emit or reflect, rather than resolving an image of them.
> Since ships are small (relative to celestial bodies) and can be painted to
> have a low albedo, they're probably not apt to reflect a lot of light.
> However, if they run on something like a fusion drive and are fast, then
> they'll glow like multi-gigawatt light bulbs. So the question becomes,
> at what range could a two-meter telescope detect the light from a multi-
> gigawatt visual radiation source? (Or, more generally, how faint an object
> can one detect with a two meter telescope?)
Don't use visible light. Use IR.
Over on the Traveller (a space RPG) mailing list, we went thru this a
while back. An astronomer on the list figured that given *current*
tech, you could detect a 100 (or was it 200?) ton ship with a
multi-megawatt power plant at several AU.
And as I noted in another post, shutting down power doesn't help much.
One of the biggest problems in spacecraft design is getting them to
radiate *enough* heat to keep the internal temp suitable for humans.
Black paint *increases* the amount of sunlight absorbed and thus makes
the ship *brighter* in the IR!
--
Leonard Erickson (aka Shadow)
sha...@krypton.rain.com <--preferred
leo...@qiclab.scn.rain.com <--last resort
Leonard Erickson
na...@mips.rhein-neckar.de (Christian Weisgerber) writes:
> Another nice weapon from the same book:
>
> "Kinetic harpoons were the Confederation Navy's standard tactical
> (non-radioactive) planetary surface assault weapon. A solid splinter
> of toughened, heat-resistant composite, half a metre long, needle
> sharp, guided by a cruciform tail, steered by a processor with a
> preprogrammed flight vector. They carried no explosives, no energy
> charge; they destroyed their target through speed alone."
>
> You "drop" a charge of these from orbit--boom! In the example in the
> book, a small ship unloads five thousand harpoons at an altitude of
> 1200km to obliterate an area of 21 km^2 in a single support strike for
> the ground troops. Ouch.
The "cruciform tail" is neither needed nor desirable. At the sort of
hypersonic speeds these will be moving, you can steer with "tabs" that
are little more than "bumps" on the hull.
The hardest part of building such is coming up with a sensor that can
see thru the plasma sheath well enough to make sure that they are on
target.
Leonard Erickson
k...@bit.csc.lsu.edu (Isaac Kuo) writes:
> Stealth in open space would take advantage of the one most obvious
> feature of open space--it's very big. No matter how sensitive one's
> sensors are, space is so big it's still possible to be further away
> than it's practical to scan reliably at (scanning requires applying
> sensitive detectors over a larger volume). This is particularly
> significant wrt sunlight--the sunlight problem gets minimal in the
> outer solar system.
>
> As long as one's weapon systems have a longer practical range than
> the enemy's practical scanning range, then it's possible to employ
> practical "stealth".
>
> Anyway, in the near future, the relative insensitivity of our
> sensors will ensure that the practical scanning range for stealthed
> spacecraft will be pretty low. Such stealthed spacecraft would
> be radar-stealthed and low albedo, but "shine" in infrared. In
> the near future, ground based sensors will greatly outnumber
> and outpower space based sensors--radar works through the
> atmosphere while IR practically doesn't. The fact that these
> ships would shine millions of times brighter than the background
> in IR is not as relevant as the fact that they still don't shine
> very brightly, so near future IR scanners will need to be relatively
> close (compared to the distances of interplanetary space) to
> scan for them.
Except for the not so trivial detail that our sensors are *not*
"relatively insensitive". And if we have *combatant* vessels in space,
we *will* have sensors out there. On the ships, if nowhere else.
IRAS detected a *lot* of small bodies, at multi-AU distances. There's
every reason to believe that both ships and "sensor bouys" will have
*better* IR detection gear.
And it *is* a good idea to spread a bunch of sensor platfoerms around
the system. That way they'll have a better chance of picking up things.
And a *much* better chance of picking up "redirected" sunlight and IR
radiation. Use lasercomm links to base, and make the platforms
relatively stealthy, and the enemy can't be sure what part of the sky
is "safe" to aim those moirrors and radiators at.
If we can't afford to do this, then delta0v must still be severely
limited, in which case that tactics change a lot anyway. With limited
delta-V dodging attacks becomes less practical. For example, consider a
"fleet" in a transfer orbit from earth to Mars. "Dodging" ordinance
gives them a vector that'll miss Mars by quite a bit (except in the
final *hours* of approach). So they have to correct back to a vector
that'll get them to Mars (or wherever). They can only do this a limited
number of times and still have fuel to match orbit with their
destination.
So in limited delta-V combat, the idea someone mentioned of sowing
"minefields" of kinetic kill ordinance ("birdshot") is a possibility.
Orbital mechanics will severely limit the possible positiuons of the
enemy, so your targetting solution becomes easier, even given the
*long* flight times involved.
Leonard Erickson
s...@xpobox.com (Peter Kwangjun Suk) writes:
> On Sun, 28 Dec 1997 21:30:21 PST, sha...@krypton.rain.com (Leonard
> Erickson) wrote:
>
>>And there's no easy way around this. Insulation does *not* reduce the
>>final temp of the hull, it just increases the time it takes to reach
>>it. And if you insulate, you are effectively *raising* the internal
>>temp, as the human bodies are providing 100 watts each of heats, as
>>well as all the electronics, etc. Remember, the *only* way to get rid
>>of heat is to *radiate* it, there's no air to conduct or convect it
>>away.
>>
>>So you either have *huge* radiators (to reduce the temp by increasing
>>the area available for getting rid of the heat) or you have a hot (and
>>thus "bright") hull. The big radiators cut down on your IR signature
>>but *increase* your radar signature.
>
> Anti-radar stealth is well understood and *completely independent of
> size*. We could build aircraft carrier size anti-radar "stealth"
> ships right now, if naval brass could get used to the idea.
But are the stealthing measures conducive to radiating large amounts of
waste heat? Especially if you want to do so in *specific* directions?
Any ship that has a powerplant capable of jaunting all over the place
is going to have to get rid of truly *massive* amounts of waste heat.
Leonard Erickson
wkd...@ix.netcom.com (Bill Dugan) writes:
> On 29 Dec 1997 15:32:40 GMT, k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
>
> snip
>
>>A potentially more serious problem is the heat absorbed from
>>sunlight (there's a _lot_ more of this than human generated heat in
>>our little neighborhood). Really, the best way to deal with the
>>heat from sunlight is to not absorb it in the first place. An
>>elongated shape with an angled mirror facing the sun (shading the
>>rest of the ship) will accomplish this, at the cost of being
>>extremely visible in a narrow cone in the direction the sunlight
>>is reflected.
>
> Rather than trying to be totally undetectable, it might be easier to
> pretend to be some random piece of debris. Cover your ship with a thin
> layer of suitable material, and let it absorb and radiate like an
> asteroid fragment.
The trouble with this is that using *any* power (including normal human
metabolism) means that you have to radiate extra heat. A natural body
is radiating exactly as much energy as it is receiving. But you are
producing *extra* energy, and it has to be radiated as well.
The smaller your surface area, the bigger the problem. At 1 AU, natural
bodies are radiating (IIRC) 1kW/m^2. So to stay within 10% of this
you'd have to have 10,000 m^2 of surface for every megawatt of power
generated. To stay within 1% (more likely for "stealth") you'd need
100,000. And you'd need 1 m^2 to 10 m^2 per crew member for the heat
*they* produce.
That sort of thing adds up *rapidly*.
Johan Forsberg
Matthew Debell wrote:
>
> A bit of reading reveals part of the answer to my own question.
> Apparently the Hubble Space Telescope is a 2.4 meter apparatus
> that can resolve a tenth of an arcsecond. If I figure correctly,
> that means it can create images with a resolution of about a meter
> at distances of several hundred kilometers.
A quick calculation yields
100,000m * sin(2pi/(360*60*60*10) = 0.048m
about 5 cm.
A 10 m object (space fighter?) can be resolved at ~20 Mm.
--
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/ Small*<-Perth Make Your Very 4 rows em...@address.here witty some
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\ Picture / Follow The Instructions v Other Personal Info said here
Isaac Kuo
In article <971230.004520...@krypton.rain.com>,
Leonard Erickson <sha...@krypton.rain.com> wrote:
>Over on the Traveller (a space RPG) mailing list, we went thru this a
>while back. An astronomer on the list figured that given *current*
>tech, you could detect a 100 (or was it 200?) ton ship with a
>multi-megawatt power plant at several AU.
This was assuming you were looking in the right place, however, when
the multi-megawatt power plant was running.
Assuming the power plant was running continuously (why?), this
is really only appropriate for tracking purposes. For scanning,
you've got to consider how much time it takes to search through
all that space.
>And as I noted in another post, shutting down power doesn't help much.
>One of the biggest problems in spacecraft design is getting them to
>radiate *enough* heat to keep the internal temp suitable for humans.
Shutting down power does help a lot! If full power is a million watts,
and minimum power is a thousand watts, you've just reduced emissions
by about a thousand-fold.
>Black paint *increases* the amount of sunlight absorbed and thus makes
>the ship *brighter* in the IR!
While this is true, in the near future radar stealth is the way to
go, even if it uses black paint which absorbs sunlight. The majority
of sensors will be ground based, which are effectively blind to this
level of IR. Space based IR sensors will be limited, in comparison,
and will be vulnerable to blinding damage by (far away) lasers and/or
nuclear explosions.
Isaac Kuo
In article <971230.012212...@krypton.rain.com>,
Leonard Erickson <sha...@krypton.rain.com> wrote:
>wkd...@ix.netcom.com (Bill Dugan) writes:
>> Rather than trying to be totally undetectable, it might be easier to
>> pretend to be some random piece of debris. Cover your ship with a thin
>> layer of suitable material, and let it absorb and radiate like an
>> asteroid fragment.
>The trouble with this is that using *any* power (including normal human
>metabolism) means that you have to radiate extra heat. A natural body
>is radiating exactly as much energy as it is receiving. But you are
>producing *extra* energy, and it has to be radiated as well.
This isn't really the problem. The amount of heat generated by humans
is small compared to the amount of heat absorbed by sunlight, so
the extra amount of power emitted will be small.
Unless the enemy has very high resolution and high sensitivity
sensors all the way around the target, he will have to merely
guess how much sunlight it is absorbing (i.e. it's
size/shape/reflectivity/transmissivity) as well as guess how
much energy it's emitting (it emits different amounts in
different directions).
>The smaller your surface area, the bigger the problem. At 1 AU, natural
>bodies are radiating (IIRC) 1kW/m^2. So to stay within 10% of this
>you'd have to have 10,000 m^2 of surface for every megawatt of power
>generated. To stay within 1% (more likely for "stealth") you'd need
>100,000. And you'd need 1 m^2 to 10 m^2 per crew member for the heat
>*they* produce.
Why would the "stealth" ship be using megawatts of power? I can
think of only 3 military uses, all of which make stealthiness moot:
1. Propulsion (a maneuvering rock isn't very convincing, even if
the exhaust was somehow stealthy)
2. Radar
3. Energy weapons fire
Anyway, I could note that 10m^2 per crew member isn't very much.
This isn't a passenger liner, it's a military vessel.
Peter Kwangjun Suk
>Don't use visible light. Use IR.
>
>Over on the Traveller (a space RPG) mailing list, we went thru this a
>while back. An astronomer on the list figured that given *current*
>tech, you could detect a 100 (or was it 200?) ton ship with a
>multi-megawatt power plant at several AU.
>
>And as I noted in another post, shutting down power doesn't help much.
>One of the biggest problems in spacecraft design is getting them to
>radiate *enough* heat to keep the internal temp suitable for humans.
>
>Black paint *increases* the amount of sunlight absorbed and thus makes
>the ship *brighter* in the IR!
You still haven't answered a point brought up by Issac and myself.
Why couldn't one build a large, radar reflecting, light reflecting,
*refrigerated* stealth-baffle? The one pictured below is a simplistic
design for invisibly approaching a point defense positioned sunward.
|----- Radiator ------|--Ship-|Mirror|
/
/
------------=========<XXXXXXX>--/
/
/
More sophisticated stealth baffles could be built using huge long,
narrow parabolic shells, which are also refrigerated as well as light
and radar absorbing on the outside and extremely reflective on the
inside. The camouflaged ship and its radiator would be situated at
the focus of the narrow parabola. In this way, *all* spacecraft
emissions could be limited to a relatively narrow cone (perhaps
60-deg) pointed in a strategically chosen direction.
Given that your thesis of easy detection of ships at vast distances is
based on those ships emitting IR like crazy, such stealth techniques
would seem to be a useful offensive tool.
Peter Kwangjun Suk
>k...@bit.csc.lsu.edu (Isaac Kuo) writes:
>
>> Stealth in open space would take advantage of the one most obvious
>> feature of open space--it's very big.
[snip]
>
>Except for the not so trivial detail that our sensors are *not*
>"relatively insensitive". And if we have *combatant* vessels in space,
>we *will* have sensors out there. On the ships, if nowhere else.
>
>IRAS detected a *lot* of small bodies, at multi-AU distances. There's
>every reason to believe that both ships and "sensor bouys" will have
>*better* IR detection gear.
>
>And it *is* a good idea to spread a bunch of sensor platfoerms around
>the system. That way they'll have a better chance of picking up things.
>And a *much* better chance of picking up "redirected" sunlight and IR
>radiation. Use lasercomm links to base, and make the platforms
>relatively stealthy, and the enemy can't be sure what part of the sky
>is "safe" to aim those moirrors and radiators at.
Ah, but now your vision of space combat is beginning to look a lot
more like mine! The sensor platforms face exactly the same problems
at implementing stealth that an attacking craft would face. Except
that an enemy has the option of choosing his/her time to attack. One
problem that the sensor platforms face is that the "better" their
stealth (The more concentrated their IR redirected IR output is) the
brighter directional beacons they become as well. By cruising outside
the patrolled volume, an attacker stands a good chance of detecting a
platform. And considering Issac's point about the bigness of space,
the subversion of one platform may be all that's necessary to enable
the use of stealth to gain an advantage.
I suppose one could build IR sensor platforms to operate at extremely
low power levels and temperatures. Especially if they are far away
from the sun and don't have to worry about absorbed sunlight as much.
But having stealthy sensor platforms everywhere is part of what I mean
when I say "In future combat, stealth will be ubiquitous!"
>If we can't afford to do this, then delta0v must still be severely
>limited, in which case that tactics change a lot anyway. With limited
>delta-V dodging attacks becomes less practical. For example, consider a
>"fleet" in a transfer orbit from earth to Mars. "Dodging" ordinance
>gives them a vector that'll miss Mars by quite a bit (except in the
>final *hours* of approach). So they have to correct back to a vector
>that'll get them to Mars (or wherever). They can only do this a limited
>number of times and still have fuel to match orbit with their
>destination.
>
>So in limited delta-V combat, the idea someone mentioned of sowing
>"minefields" of kinetic kill ordinance ("birdshot") is a possibility.
>Orbital mechanics will severely limit the possible positiuons of the
>enemy, so your targetting solution becomes easier, even given the
>*long* flight times involved.
Which sounds a lot like WWII submarine combat. I agree that one will
still have ships that are designed for manuverability. But these will
have to watch out for the stealthy ships, which will provide
intelligence to the fast ships of its own fleet and occasionally take
down "targets of opportunity" in the form of enemy ships that
unwittingly get too close.
Isaac Kuo
In article <971230.010043...@krypton.rain.com>,
>> Anyway, in the near future, the relative insensitivity of our
>> sensors will ensure that the practical scanning range for stealthed
>> spacecraft will be pretty low. [...]
>Except for the not so trivial detail that our sensors are *not*
>"relatively insensitive". And if we have *combatant* vessels in space,
>we *will* have sensors out there. On the ships, if nowhere else.
Yes, but size and cost are limiting factors.
>IRAS detected a *lot* of small bodies, at multi-AU distances. There's
>every reason to believe that both ships and "sensor bouys" will have
>*better* IR detection gear.
Yes, but it takes time to scan at those distances. Unless IRAS
can detect _all_ the small bodies at 1AU within, say, a week, it
doesn't have a practical scanning range of 1AU.
Being able to track a target at 1AU is a good, plausible, capability,
but that doesn't imply that you can practically scan at that range!
>And it *is* a good idea to spread a bunch of sensor platfoerms around
>the system. That way they'll have a better chance of picking up things.
>And a *much* better chance of picking up "redirected" sunlight and IR
>radiation.
I agree with you here, but there's a big issue of cost. Because of
cost and blinding considerations, I would expect such sensor drones
to be primarily designed to detect the high energy emissions of
redirected sunlight. A small radar, ladar, and/or IR telescope
would be used to turn a sporadic detection of a bit of redirected
sunlight into a tracking solution.
However, using the radar or ladar to scan with has obvious stealth
problems, and a sensitive IR telescope with a wide area scan
capability would be much more expensive and be vulnerable to
damage from nuclear explosions.
>Use lasercomm links to base, and make the platforms
>relatively stealthy, and the enemy can't be sure what part of the sky
>is "safe" to aim those moirrors and radiators at.
This is true, but the enemy can also use that redirected sunlight
to try and detect anything within that cone. If a passive sensor
drone is detected and destroyed (e.g. with laser fire) before it
can determine range to target, then the enemy has only an estimate
of your position.
(A radar or ladar would determine range to target practically
instantly, but ECM and/or stealth is possible. Passive IR
triangulation with two slightly spaced apart sensor drones
is harder to counter, but it takes a significant amount of
time for sensitive IR sensors to slew into position.)
>If we can't afford to do this, then delta0v must still be severely
>limited, in which case that tactics change a lot anyway.
Well, I include near future ballistic missile defense as examples
of space combat, so I take it as a given that the tactics greatly
depend upon the technology involved.
In the near future, delta-v will almost certainly be severely
limited, with Isps for high thrust rockets being at most 1000secs.
>With limited
>delta-V dodging attacks becomes less practical. For example, consider a
>"fleet" in a transfer orbit from earth to Mars. "Dodging" ordinance
>gives them a vector that'll miss Mars by quite a bit (except in the
>final *hours* of approach).
Actually, this depends upon how much they need to maneuver in order to
dodge the ordinance. If the ordinance is unguided (huh?) then a
fraction of a second burn several minutes from impact to dodge and
another fraction of a second burn to bring one into a (new) transfer
orbit is sufficient. With thermal nuclear rockets, each ship could
to this thousands of times with fuel to spare.
If the ordinance is guided, then with most technology assumptions
the ordinance can outmaneuver the targets anyway. (With some
technology assumptions, guided missiles have lower Isp than the
targets, which lead to quite fascinating tactics, but they're
somewhat contrived assumptions.)
>So in limited delta-V combat, the idea someone mentioned of sowing
>"minefields" of kinetic kill ordinance ("birdshot") is a possibility.
>Orbital mechanics will severely limit the possible positiuons of the
>enemy, so your targetting solution becomes easier, even given the
>*long* flight times involved.
It's a possibility, but one which I think is less likely than
the idea of "slinging" such a "minefield" at the enemy. Even
with the limitations of orbital mechanics, it's impractical
to lay minefields all around a planet--you still would need to
have a good idea of where the enemy is in order to somewhat
predict his future position.
So assuming you are tracking the enemy, why wait around for him
to reach the target area? For the price of a few relatively
small "machine guns" (e.g. rapid fire railguns), you can sling
those little projectiles at him in a massive time-on-target
barrage which will hit him harder, faster, and sooner than if
you just lay it across his path.
It's plausible to have a compact railgun capable of 10km/sec
shots with 1000rpm on each warship. A fleet of 10 ships firing
continuously for a day could put up a wall of 14 million
projectiles, all timed to hit the target zone simultaneously.
Assuming the targets have a relative velocity of 20km/sec with
the firing platforms, the projectiles will hit with more than
twice the kinetic energy than if those projectiles were laid
in a "minefield". Importantly, these projectiles will hit
while the enemy is still far away from the fleet.
Peter Kwangjun Suk
On 30 Dec 1997 02:57:44 GMT, k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
>In article <34A83F28...@interaccess.com>,
>Paul Dietz <di...@interaccess.com> wrote:
>>Bill Dugan wrote:
>
>>> Rather than trying to be totally undetectable, it might be easier to
>>> pretend to be some random piece of debris. Cover your ship with a thin
>>> layer of suitable material, and let it absorb and radiate like an
>>> asteroid fragment.
>
>The problem is that there aren't that many random pieces of debris
>around, and they'll probably all be charted. It's kind of like a
>naval vessel trying to pretend to be a random island. Not very
>convincing!
What about small rocks? Surely not evey 1 meter rock in a sytem will
be charted. If you can change your radar and IR signature so that you
look like a 1 meter rock from certain directions, this is going to be
valuable.
In fact, it seems entirely resonable that a autonomous AI
reconnaisance drone could be quite good at looking like a 1 meter
rock.
Brian Davis
In an article, s...@xpobox.com wrote:
> On Tue, Leonard Erickson wrote:
>
> >And as I noted in another post, shutting down power doesn't help much.
> >One of the biggest problems in spacecraft design is getting them to
> >radiate *enough* heat to keep the internal temp suitable for humans.
>
> You still haven't answered a point brought up by Issac and myself.
> Why couldn't one build a large, radar reflecting, light reflecting,
> *refrigerated* stealth-baffle?
> ...
> Given that your thesis of easy detection of ships at vast distances is
> based on those ships emitting IR like crazy, such stealth techniques
> would seem to be a useful offensive tool.
Above and beyond this, there are at least two other ways to "stealth"
ships in the IR.
#1, store the excess heat, don't release it. Yes, you *can* do this,
but it will cost you energy, and you obviously can't do it forever - you
have to dump the waste heat *somewhere*, and due to "refridgerating" it,
you'll have even more to dump. Good only for the *very* short term.
#2, as you mention, direct your waste heat in a direction it's unlikely
to be seen. Your idea of a "refridgerated stealth-baffle" is a good idea,
but it can be taken a step further. Take your waste heat, concentrate it,
and dump it in a *very* limited direction. This idea was used in Brin's
book "Sundiver", using a refridgerator laser. Highly directional, so as
long as you don't point it where you think your enemy is, no problem. As a
bonus, if it could be redirected quickly it could serve as a weapon (a lot
of if's there, but a avenue worth exploring).
-Brian Davis
Bill Dugan
On Tue, 30 Dec 1997 15:26:25 GMT, s...@xpobox.com (Peter Kwangjun Suk)
wrote:
snip
>You still haven't answered a point brought up by Issac and myself.
>Why couldn't one build a large, radar reflecting, light reflecting,
>*refrigerated* stealth-baffle? The one pictured below is a simplistic
>design for invisibly approaching a point defense positioned sunward.
picture snipped
>More sophisticated stealth baffles could be built using huge long,
>narrow parabolic shells, which are also refrigerated as well as light
>and radar absorbing on the outside and extremely reflective on the
>inside. The camouflaged ship and its radiator would be situated at
>the focus of the narrow parabola. In this way, *all* spacecraft
>emissions could be limited to a relatively narrow cone (perhaps
>60-deg) pointed in a strategically chosen direction.
>
>Given that your thesis of easy detection of ships at vast distances is
>based on those ships emitting IR like crazy, such stealth techniques
>would seem to be a useful offensive tool.
What's to stop the defenders from scattering small stealthy IR
detecting platforms where the attackers would be likely to pass them?
Since such platforms wouldn't need to generate much power, they'd be
easier to conceal than ships.
Bill Dugan
On Tue, 30 Dec 1997 01:22:12 PST, sha...@krypton.rain.com (Leonard
Erickson) wrote:
>wkd...@ix.netcom.com (Bill Dugan) writes:
>
Older quotes snipped
>> Rather than trying to be totally undetectable, it might be easier to
>> pretend to be some random piece of debris. Cover your ship with a thin
>> layer of suitable material, and let it absorb and radiate like an
>> asteroid fragment.
>
>The trouble with this is that using *any* power (including normal human
>metabolism) means that you have to radiate extra heat. A natural body
>is radiating exactly as much energy as it is receiving. But you are
>producing *extra* energy, and it has to be radiated as well.
>
>The smaller your surface area, the bigger the problem. At 1 AU, natural
>bodies are radiating (IIRC) 1kW/m^2. So to stay within 10% of this
>you'd have to have 10,000 m^2 of surface for every megawatt of power
>generated. To stay within 1% (more likely for "stealth") you'd need
>100,000. And you'd need 1 m^2 to 10 m^2 per crew member for the heat
>*they* produce.
True. The sort of stealth tricks being discussed in this thread work
only while the stealthy ship is staying quiet and not generating much
power. While it is doing so, it's a lot easier to come close to
matching a 300K object than the 3K some have suggested.
Bill Dugan
On 30 Dec 1997 02:57:44 GMT, k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
>In article <34A83F28...@interaccess.com>,
>Paul Dietz <di...@interaccess.com> wrote:
>>Bill Dugan wrote:
>
>>> Rather than trying to be totally undetectable, it might be easier to
>>> pretend to be some random piece of debris. Cover your ship with a thin
>>> layer of suitable material, and let it absorb and radiate like an
>>> asteroid fragment.
>
>The problem is that there aren't that many random pieces of debris
>around, and they'll probably all be charted. It's kind of like a
>naval vessel trying to pretend to be a random island. Not very
>convincing!
The usefulness of this kind of trick would depend on location. By the
time we can build ships like those discussed here, we'll probably have
charted all the reasonably large objects that regularly pass near
Earth. OTOH, it's likely to be quite a bit longer before we've mapped
every ship-sized object in the main asteroid belt.
Peter Kwangjun Suk
On Tue, 30 Dec 1997 17:44:13 GMT, wkd...@ix.netcom.com (Bill Dugan)
wrote:
>On Tue, 30 Dec 1997 15:26:25 GMT, s...@xpobox.com (Peter Kwangjun Suk)
>wrote:
>
>snip
>>You still haven't answered a point brought up by Issac and myself.
>>Why couldn't one build a large, radar reflecting, light reflecting,
>>*refrigerated* stealth-baffle? The one pictured below is a simplistic
>>design for invisibly approaching a point defense positioned sunward.
[snip]
>>
>>Given that your thesis of easy detection of ships at vast distances is
>>based on those ships emitting IR like crazy, such stealth techniques
>>would seem to be a useful offensive tool.
>
>What's to stop the defenders from scattering small stealthy IR
>detecting platforms where the attackers would be likely to pass them?
>Since such platforms wouldn't need to generate much power, they'd be
>easier to conceal than ships.
I address this in another post. Nothing would prevent this. But
these will have to stay hidden for the long term. An attacker has the
option of taking his time and ferreting out the detecting platforms
ahead of time. And just that fact that a network of platforms would
have to be maintained is a testament to stealth.
Peter Kwangjun Suk
>In an article, s...@xpobox.com wrote:
>
>> On Tue, Leonard Erickson wrote:
>>
>> >And as I noted in another post, shutting down power doesn't help much.
>> >One of the biggest problems in spacecraft design is getting them to
>> >radiate *enough* heat to keep the internal temp suitable for humans.
>>
>> You still haven't answered a point brought up by Issac and myself.
>> Why couldn't one build a large, radar reflecting, light reflecting,
>> *refrigerated* stealth-baffle?
[snip]
> #2, as you mention, direct your waste heat in a direction it's unlikely
>to be seen. Your idea of a "refrigerated stealth-baffle" is a good idea,
>but it can be taken a step further. Take your waste heat, concentrate it,
>and dump it in a *very* limited direction. This idea was used in Brin's
>book "Sundiver", using a refridgerator laser. Highly directional, so as
>long as you don't point it where you think your enemy is, no problem. As a
>bonus, if it could be redirected quickly it could serve as a weapon (a lot
>of if's there, but a avenue worth exploring).
> -Brian Davis
This has been discussed at length here before. I think this violates
thermodynamics.
David Art
Peter Kwangjun Suk wrote in message <34a943e2...@news2.ibm.net>...
>On Tue, 30 Dec 1997 12:48:26 -0500, da...@miphys.physics.lsa.umich.edu
>(Brian Davis) wrote:
>
>>In an article, s...@xpobox.com wrote:
>>
>>> On Tue, Leonard Erickson wrote:
>>>
>>> >And as I noted in another post, shutting down power doesn't help much.
>>> >One of the biggest problems in spacecraft design is getting them to
>>> >radiate *enough* heat to keep the internal temp suitable for humans.
>>>
>>> You still haven't answered a point brought up by Issac and myself.
>>> Why couldn't one build a large, radar reflecting, light reflecting,
>>> *refrigerated* stealth-baffle?
>[snip]
>> #2, as you mention, direct your waste heat in a direction it's unlikely
>>to be seen. Your idea of a "refrigerated stealth-baffle" is a good idea,
>>but it can be taken a step further. Take your waste heat, concentrate it,
>>and dump it in a *very* limited direction. This idea was used in Brin's
>>book "Sundiver", using a refridgerator laser. Highly directional, so as
>>long as you don't point it where you think your enemy is, no problem. As a
>>bonus, if it could be redirected quickly it could serve as a weapon (a lot
>>of if's there, but a avenue worth exploring).
>
>This has been discussed at length here before. I think this violates
>thermodynamics.
What if you used a chemical or mechanical means to translate the heat into
1. chemical bonds in crystals or 2. spinning a large mass. ie a generator.
Dave
Doug Lampert
In article <34a9267b...@news2.ibm.net>,
Peter Kwangjun Suk <s...@xpobox.com> wrote:
>On 30 Dec 1997 02:57:44 GMT, k...@bit.csc.lsu.edu (Isaac Kuo) wrote:
>
>>In article <34A83F28...@interaccess.com>,
>>Paul Dietz <di...@interaccess.com> wrote:
>>>Bill Dugan wrote:
>>
>>>> Rather than trying to be totally undetectable, it might be easier to
>>>> pretend to be some random piece of debris. Cover your ship with a thin
>>>> layer of suitable material, and let it absorb and radiate like an
>>>> asteroid fragment.
>>
>>The problem is that there aren't that many random pieces of debris
>>around, and they'll probably all be charted. It's kind of like a
>>naval vessel trying to pretend to be a random island. Not very
>>convincing!
>
>be charted. If you can change your radar and IR signature so that you
>look like a 1 meter rock from certain directions, this is going to be
>valuable.
Why in the world do you assume a civilization capable of space warfare will
not have plotted the location of every 1 meter rock in the system, we plot
objects in earth orbit down to a much smaller size, there could not be much
more the 10^20 or so such rocks in any given system, tracking all orbital
motion of such rocks requires the 22nd century equivalent of a home computer,
at most. (Plus an automated observatory for updates.)
Giving each of my sensors an expected background map with the few trillion
most prominent objects in its field of view (+ their motions) for the next
week would seem a trivial problem. And is obviously worth doing.
A few centuries ago the idea that we would be able to give every warship a
map of every island in every ocean of the world would have seemed absurd.
In practice we now give them topographic maps accurate to meters of even
land locked areas in case they need to program a cruise missile.
A few centuries from now I have every confidence that if we are building
space warships they will carry 'maps' showing their battlefields with objects
down to square centimeters in cross section noted and plotted.
DougL
Doug Lampert
In article <davis-30129...@pm010-25.dialip.mich.net>,
Brian Davis <da...@miphys.physics.lsa.umich.edu> wrote:
> #1, store the excess heat, don't release it. Yes, you *can* do this,
>but it will cost you energy, and you obviously can't do it forever - you
>have to dump the waste heat *somewhere*, and due to "refridgerating" it,
>you'll have even more to dump. Good only for the *very* short term.
> #2, as you mention, direct your waste heat in a direction it's unlikely
>to be seen. Your idea of a "refridgerated stealth-baffle" is a good idea,
>but it can be taken a step further. Take your waste heat, concentrate it,
>and dump it in a *very* limited direction. This idea was used in Brin's
>book "Sundiver", using a refridgerator laser. Highly directional, so as
>long as you don't point it where you think your enemy is, no problem. As a
>bonus, if it could be redirected quickly it could serve as a weapon (a lot
>of if's there, but a avenue worth exploring).
> -Brian Davis
Problem for the day, calculate the total entropy carried by a laser beam,
discuss the relevance of this to Brin's use of a 'cooling laser'.
Hint for the student, a laser is effectively 100% usable energy,
waste heat is not. Brin used a perpetual motion machine to make that
ship work.
DougL
Peter Kwangjun Suk
On 30 Dec 1997 14:17:02 -0600, lam...@s10.math.uah.edu (Doug Lampert)
wrote:
>In article <34a9267b...@news2.ibm.net>,
>Peter Kwangjun Suk <s...@xpobox.com> wrote:
[snip]
>>>The problem is that there aren't that many random pieces of debris
>>>around, and they'll probably all be charted. It's kind of like a
>>>naval vessel trying to pretend to be a random island. Not very
>>>convincing!
>>
>>What about small rocks? Surely not evey 1 meter rock in a sytem will
>>be charted. If you can change your radar and IR signature so that you
>>look like a 1 meter rock from certain directions, this is going to be
>>valuable.
>
>Why in the world do you assume a civilization capable of space warfare will
>not have plotted the location of every 1 meter rock in the system, we plot
>objects in earth orbit down to a much smaller size, there could not be much
>more the 10^20 or so such rocks in any given system, tracking all orbital
>motion of such rocks requires the 22nd century equivalent of a home computer,
>at most. (Plus an automated observatory for updates.)
Ouch! Okay, I concede. And, considering the number of pieces of
military hardware that have enough MIPS to be considered
flying/floating supercomputers*, this seems plenty reasonable for even
20 years time.
>Giving each of my sensors an expected background map with the few trillion
>most prominent objects in its field of view (+ their motions) for the next
>week would seem a trivial problem. And is obviously worth doing.
But developing such maps is going to take time for any given volume of
space.
>A few centuries ago the idea that we would be able to give every warship a
>map of every island in every ocean of the world would have seemed absurd.
>In practice we now give them topographic maps accurate to meters of even
>land locked areas in case they need to program a cruise missile.
>
>A few centuries from now I have every confidence that if we are building
>space warships they will carry 'maps' showing their battlefields with objects
>down to square centimeters in cross section noted and plotted.
I wouldn't have any confidence about predicting what might be
happening in the 22nd century. The likelihood that our discussion
would have any relevance at that time seems as small as the chance of
predicting what's happening today in 1797.
But you're right about the information part. Bit by Moore's law.
--PKS
* - This is due in part to the military's profligate use of quite
powerful microcomputers in embedded applications.
Peter Kwangjun Suk
[Physics people abort now!]
On Tue, 30 Dec 1997 11:54:52 -0800, "David Art"
<davi...@sierra.campus.mci.net> wrote:
>
>Peter Kwangjun Suk wrote in message <34a943e2...@news2.ibm.net>...
>>On Tue, 30 Dec 1997 12:48:26 -0500, da...@miphys.physics.lsa.umich.edu
>>(Brian Davis) wrote:
[snip]
>>> #2, as you mention, direct your waste heat in a direction it's unlikely
>>>to be seen. Your idea of a "refrigerated stealth-baffle" is a good idea,
>>>but it can be taken a step further. Take your waste heat, concentrate it,
>>>and dump it in a *very* limited direction. This idea was used in Brin's
>>>book "Sundiver", using a refridgerator laser. [snip]
>>
>>This has been discussed at length here before. I think this violates
>>thermodynamics.
>
>What if you used a chemical or mechanical means to translate the heat into
>1. chemical bonds in crystals or 2. spinning a large mass. ie a generator.
>
>Dave
"Uh, like, is this a troll?" (Reference to another thread. ;-)
Same thing here. You're going from high entropy to low entropy. You
can do this so long as you're also doing more of the opposite. (i.e.
you give off some waste heat.)
If you could do this with perfect efficiency, you get perpetual
motion. If you don't have perfect efficiency, then you're going to
have some waste heat, so what's the point?
Three laws of thermodynamics for gamblers:
1) You can't win
2) You can't break even
3) You can't get out of the game
Do I have this right?
--PKS
(Paranoid note: are you guys making fun of me by repeating suggestions
I've made here in my clueless undergraduate days? I notice that Brian
is posting from a physics domain.)
(Not so paranoid note: why wouldn't the baffle idea work? Are you
guys implying that it wouldn't?)
(Truly paranoid note: you're 5th column aliens trying to convince us
that an important space-combat technique is not important, in
preparation for your invasion to steal our planet's water resources!
;-)
Peter Kwangjun Suk
>A few centuries from now I have every confidence that if we are building
>space warships they will carry 'maps' showing their battlefields with objects
>down to square centimeters in cross section noted and plotted.
>
>DougL
Then again, lightspeed delays are going to play havoc with this idea
in very densely populated systems. (Tens or hundreds of billions.)
You're going to have a heck of a lot of objects out there that can
manuver on their own power. Not only colonies, but ships, depots, and
all sorts of semi-autonomous robots. And because of lightspeed
delays, you won't know that's happening for hours. Additionally,
who's to say that the population of a such a system isn't
factionalized to a point where the different groups don't cooperate?
Good luck trying to keep track of all that.
Even limited stealth (The ability to pose as something with a much
smaller IR and radar signature) would make it possible for an
multi-megawatt interloper to pose as a harmless little civilian or a
neutral party.
--PKS
Erik Max Francis
Isaac Kuo wrote:
> Shutting down power does help a lot! If full power is a million
> watts,
> and minimum power is a thousand watts, you've just reduced emissions
> by about a thousand-fold.
Which means a 1000^(1/4) = 5.6 decrease in the hull temperature.
--
Erik Max Francis, &tSftDotIotE / mailto:m...@alcyone.com
Alcyone Systems / http://www.alcyone.com/max/
San Jose, California, United States / icbm://+37.20.07/-121.53.38
\
"Life may be / the product of imperfections."
/ (Marclo Gleiser)
Erik Max Francis
Johan Forsberg wrote:
> A quick calculation yields
>
> 100,000m * sin(2pi/(360*60*60*10) = 0.048m
>
> about 5 cm.
A somewhat more accurate relation would be
tan (theta/2) = r/(2 R),
where theta is the subtended angle, r is the size of the object, and R
is its distance, but for angles this small, it doesn't make much
difference.
> A 10 m object (space fighter?) can be resolved at ~20 Mm.
By comparison, the Earth's diameter is 12.7 Mm, and Neptune's diameter
is 44.4 Mm. Even in interplanetary space, 20 Mm ain't much. (The
Earth-Moon distance is 384 Mm; the Earth-Sun distance is 150 000 Mm.)
Now, that being said, spotting the enemy is more likely going to be
because of electromagnetic emissions, which will increase the range
greatly.