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.