> At 1:29 PM 10/28/96, Mike Miserendino wrote:> Oerjan Ohlson wrote:
Detecting a target by active (radar) means that you have the range by default.
You measure how long it takes for each radar pulse to return, radar propagates
at the speed of light so the math is simple. Passive systems are less certain,
but fire control will probably have to use active sensors for energy weapons.
See the Traveller games (Fire, Fusion and Steel; Brilliant Lances, Battle
Rider) for more on this.
> >Well... your Weapons Officer should devote his entire attention to
There's some rules in More Thrust about exactly this.
> Some actions to watch for:
The above list of warning signs points immediately to some tactics. Most
notably, withdraw lightly damaged ships from close action. This forms a
reserve in plain sight. It's a deception tactic, but Honor Harrington used
even more unlikely tactics to try and gain an edge.
> Mike Miserendino
Date sent: 29-OCT-1996 09:26:02
> Detecting a target by active (radar) means that you have the range by
But if you are using Radar, you are lit up like a Christmas tree for all
around to see. I'd say passive sensors are more likely as you wouldn't have to
give away your own position. Think of it like Subs. Contrary to Hollywood,
they don't go about 'pinging' all the time. They run silent, using passive
listening devices. I would imagine our ships would do the same.
I once read a book, can't remember which one, but one of those 'Aliens have
visited Earth. Honest Guv.' ones that discussed the possibility of spotting an
incoming alien vessel. Independance Day got it right. We wouldn't be able to
spot even a Gargantuan vessel until it was inside the moons orbit. The chances
of any Astronomer looking at the right spot in space are just too small, even
with Radio Telescopes et al. Over the ranges depicted in Full Thrust, our much
smaller ships would be much harder to spot, hence the lack of accurate
positional data.
Date sent: 29-OCT-1996 10:02:48
> Did we discuss active weapon sensors here, or was it somewhere else?
Hmm..
> anyway, the point is radar/laser active sensors just don't work in
I've seen this kind of argument before. If this were true, an aircraft could
never hit another aircraft with guns, but they can. Why? because you aim where
you plot the target to be rather than where it was. And fire multiple rounds
in that area in case it maneuvers. Just because the speed of your weapons has
increased does not mean that you can't plot offset.
The same thing applies in space. With computerised targeting solutions,
a ship with a relative 'speed' of 10kms-1 is as easy to hit as a
stationary
target. Now if it were accelerating at 10kms-2, it would still be an
easy target. It would have to be accelerating by random amounts between
+- 10kms-2 before the figures quoted are accurate. (And I'd like to see
the
crew survive a 10kms-2 acceleration.(about 1000G)).
On [Tue, 29 Oct 1996 09:37:05 +0100] Adam Delafield
> <A.Delafield@bolton.ac.uk> wrote:
> >Detecting a target by active (radar) means that you have the range
Passive
> >systems are less certain, but fire control will probably have to
Contrary to
> Hollywood, they don't go about 'pinging' all the time. They run
Did we discuss active weapon sensors here, or was it somewhere else?
Hmm..
anyway, the point is radar/laser active sensors just don't work in space
combat. Why? Follow this through..
Say you are in one ship, and you have a radar tansceiver, and you have it
pointed at the other ship. Say the other ship is doing reasonable
deep space speed oooh, 10KM/S (which, to use a quote, is just peanuts
to space). Say it's.01 light seconds away. You bounce an emitted pulse off it
and it takes.01 of a second to get back to you. In that.01 of a second, the
vehicle you were locked on to has moved 100 meters. In actual terms, you would
be lucky to get that close and you would be lucky if in combat conditions a
vehicle was moving that slowly, but say you take that reading and fire your
xhundred gigawatt laser at it. In the time it takes the beam to reach it's
target, it's moved (aproximately) ANOTHER
100 meters too - so now if you aimed at the middle of it it would have
to be at least 400M wide or you've missed it.
This is a of course a simple case - if it's moving directly away or
towards you it isn't a problem. Nevertheless a ship with significant G
maneuvering capability will be bloody hard to hit using active sensor locks.
Much better to track it over time and try to predict it's location
when your beam arrives - 'lead fire' as it were. And you can do that
just as easily with passive sensors as active.. Then of course you have
problems with beam smearing at space level velocities, but that's another
point. There is an article in an old Challenge (GDW) magazine, written about
the time they were developing Brilliant Lances, about the unfeasibility
of beam weapons in space combat - basically you need a super accurate
estimate of the targets velocity, coupled with a superaccurate ability to
track your laser with the targets movement before you can even THINK of
putting enough joules in one place to burn through anything..
The main thing about it is that it makes space combat a lot like submarine
combat - if the enemy can see you and you can't see him you are in deep
deep trouble, because he can plot a firing solution without you being able to
'spoil' it.
Doesn't stop it being huge fun to give someone a multiple A battery broadside
at 3" of course..
TTFN
JOn
Date sent: 29-OCT-1996 11:07:00
> Say for a ship that's approximately
Erm..
To move 100m in 0.2sec is a velocity of 500ms-1. Your acceleration has
to be
much greater than that. (You have to accelerate to 1000ms-1, assuming
linear acceleration (The area under your velocity v time graph gives distance)
in 0.2,
which is 5000ms-2.) Well, you get the idea.
> but I doubt it's anywhere near 1000G.
It's only about 500G. 8-)
A 9g maneuver (still pretty steep) would give you about 5 meters (18 feet?) in
0.2 seconds.
> I've always considered this an interesting subject actually. There are
Have you seen that new gizmo from America that can track a bullet in flight
back to it's source and return fire? Don't see why you can't do that with
energy weapons. Track the enemy by his shooting at you.
On [Tue, 29 Oct 1996 10:13:07 +0100] Adam Delafield
> <A.Delafield@bolton.ac.uk> wrote:
> I've seen this kind of argument before. If this were true, an
because
> you aim where you plot the target to be rather than where it was.
And
> fire multiple rounds in that area in case it maneuvers. Just
Firing guns by eye is a lot different than firing a laser over 1000's of
KM of course but the reasoning is correct - and I did mention it. You
can hit your target *IF* you can accurately predict where it is going to
be so you can make sure your projectile/pulse can intercept it.
Therefore the problem is not actually detecting the other craft, but detecting
it's velocity etc accurately enough to hit it a VERY large distance..
> The same thing applies in space. With computerised targeting
The point is that the calculations and the measurements have to be accurate
to the point of stupidity - in fact to the point where Heizenburg's
Uncertainty principle gets involved. By how much of degree of arc does your
laser pointing system have to be out for you to miss a ship sized target many
kilometers away? Your example is valid if and only if the
object is unable to change it's KM/S*S sufficiently in the time, but it
doesn't need to be anywhere near the figure you are quoting - all it
needs to do is change it enough so that no bit of it is in the place it would
have been, if you see what I mean. Say for a ship that's approximately a 200m
sphere, it would have to change it's acceleration enough to be 100m from it's
predicted point in the period between the targetting
pulse arriving and the energy beam - in that case it's moved 100m
differently in.2 of a second. It's a hard G move (and I can't work out exactly
how hard now as I have the flu and that sort of thing is VERY complicated) but
I doubt it's anywhere near 1000G. All it would have to do is slightly alter
it's course so that in.2 seconds it's 100m to the left, right up or down (or
any two combined) of it's previous course position. That means that the best
way to do hit it is not to give it that.2 of a second,
and the best way to do that is passive targetting - it won't know it's
being shot at until the beam arrives..
I've always considered this an interesting subject actually. There are
lots of possibilities apart from hard movement - quick blooming
aerosols, anti-
battery fire (well if you're going to shout 'here I am' it serves you
right..)
TTFN
Jon
On [Tue, 29 Oct 1996 11:33:09 +0100] Adam Delafield
> <A.Delafield@bolton.ac.uk> wrote:
> Erm..
Grin, I haven't got my maths head on right now but your figures look right. I
did say though that.2 of a second was actually a pretty generous estimate of
the interval. How far is.1 of a light second anyway? Is it a 'reasonable'
distance to expect Full Thrust combat to take place in? As I remember ( and
right now it would not suprise me in the LEAST if I was wrong, as I am having
some trouble remembering my own name I have
such a headache ) C is roughly 3X10^8 M/S isn't it? or 3X10^5
KM/S. Therefore .1 light second is 3X10^4 or 30,000 KM. Something in the
order of planetary diameter. Hmm.. bit close for my liking..
> >I've always considered this an interesting subject actually. There
My first thought about those was 'I'm sure it'll make you very happy after you
are dead', given they apparently didn't make any effort to stop the bullet
hitting you. Now is it possible that a ship could launch some
sort of solid object to intercept the beam before it hit the ship - some
sort of anti-energy beam missile.. It wouldn't have to get that far away
from the ship as long as it could absorb enough energy. I hope they have
good computers in the (whatever)th century :-). I always thought it was
somewhat odd that scifi authors could quite willingly accept that there are
computers that fast around in their 'time' but not that they could be equipped
with AI pilots who wouldn't care less what G they were subjected
to..
TTFN
Jon
> JOn wrote:
Hmm..
> anyway, the point is radar/laser active sensors just don't work in
:
> second, the vehicle you were locked on to has moved 100 meters. In
:
> point. There is an article in an old Challenge (GDW) magazine, written
The incredible accuracy needed to create a target solution would most likely
be calculated by computerized fire control systems. The capability of the fire
control system would be the chief limiting factor of any directed energy
weapon system. It is not impossible to generate a target solution, even using
today's technology for such a weapon. It is just difficult to reach the full
capability of the directed energy weapon.
Many articles have been written regarding the pros/cons of space borne
sensors in combat. Radar and laser type systems still seem likely to prevail
for years to come as the main type of sensors available for such weapon
systems to operate.
> The main thing about it is that it makes space combat a lot like
Yes, space combat does share quite a bit with submarine combat. I always liked
the expression found in Traveller:2300, "It's like hide and seek with
bazookas."
> Adam Delafield writes:
@:)
@:) [ about high-g manouvers and shooting things in space with lasers ]
Probably all these calculations are not completely impossible, at least if
we're not talking about relativistic speeds. Your next problem would be
getting a beam that can actually get to the target. Right now that is so far
beyond our capabilities that it's not even funny. Railguns work ok, though.
But not as good as the BMSO people say they do.
I think if the people in FT have enough technology to shoot at things that are
hundreds, thousands or maybe even millions of kilometers away, they probably
have the technology to hit them.
Oh and as for radar lighting one's self up for everyone to see, some of you
might be interested to read an article in the November (?) issue of Scientific
American about detectors that don't interact with the detected object. Well,
they do, but to a tunable and arbitrarily
small extent. It might be completely possible to make an _extremely_
low emissions radar system at some time in the future.
The discussion went:
> The main thing about it is that it makes space combat a lot like
Where the best/only pratical weapon is a guided missile (torpedo), beam
weapons (deck guns) can only be used close up and personal. This is the logic
in the Honor Harrington Universe as well.
Tim
> Recently Jon wrote:
> I hope they have
Joe Haldeman actually referred to the problem you describe in "Forever
War".
His warship/troop transport would enter a target system with the crew
and
marines sedated in jelled "anti-acceleration capsules". The ship's
onboard AI would then fight the battle without worry for how many Gs were
being pulled at what time, subject to the structural limits of the spacecraft.
No
reaction time problems, hesitation, or second thoughts. If the computer
awakened you then you'd won the battle. If not, you never knew it.
The excellent "Aliens" Tech Manual by Lee Brimmicombe-Wood describes
similar
procedures for the Conestoga-class (Sulacco) warships. They sometimes
have a human bridge crew during battle, however.
The comment made uptopic about "realistic" space combat being a lot like
submarine warfare is right on. Theoretical detection ranges could be huge, IF
you knew which way to look. For that reason "stealth" would be an important
part of ship design and tactics. It would also tend to shrink
down the size of the battle. Big, multi-class battle fleets would
probably
be easier to detect than single multi-purpose ships. Using active
sensors would just finalize the enemy's firing solution for him so that's out.
Add to all this the problem of energy weapon beam divergence over distance and
you get tactics and weapons as indicated in the "Aliens" book: Missiles
(puncturing or submunition, rather than blast warheads, stealthy,
multi-sensor), railguns (possibly with terminally guided projectiles),
and
point-defense lasers. Most of the scientist types I talk to tell me
that the concept of particle accelerators as weapons over long distances is
still a bit premature. This scenario also lends itself well to the "combat
drone" idea discussed on this list earlier this year and featured in the
computer game "Mission: Critical".
I'd like to see some ideas for using the FT rules to simulate this type of
"realistic" space combat. Yes, it probably isn't quite as romantic as massive
space fleets blasting away at one another but could still be fun in a
different way. Detection and development of firing solutions would be as
important as the firing itself. This could be handled by treating the sensors
as "batteries" in their own right. One would have to "hit" the target for a
certain number of "detection points" in order to get a firing solution for
their weapons. Stealth ("shielding") would be based on target thrust, aspect
(facing relative to firer), and active sensor or weapons use.
Yes, it could get complicated but: a. only a few ships per side would be
involved, and b. I know that there are some *very* clever individuals out
there among us who can come up with elegant solutions to complex problems.
Have at it then.
Adam Delafield writes,
> But if you are using Radar, you are lit up like a Christmas tree for
But whatever PSB you use for spaceship propulsion is likely to be a good deal
"noisier" than a submarine propellor, right? A ship using nuclear pulse
propulsion or fusion ramjets or whatever would also be lit up anytime it uses
thrust. Even when it wasn't actively using thrust, as long as the engines are
"warm" they would probably still send out quite a signature. (Unless your
ships use solar sails or something.) I always figured that was primarily how
spaceships detected one another, not visually but by detecting drive emissions
and other "energy signatures."
Scott Field
> joachim wrote:
What's BMSO?
> I think if the people in FT have enough technology to shoot at
Ditto.
> Oh and as for radar lighting one's self up for everyone to see, some
As well as extremely low emission radar detectors.;) New technology has a very
short lifespan as cutting edge.
> Mike Miserendino writes:
@:) What's BMSO?
I think I meant BMDO. Let's see, that would be the Ballistic Missile Defense
Organization. I may have gotten even that wrong. Anyway they're SDI reborn.
And still doing cool, if probably somewhat
impractical, stuff, like anti-missile missiles and railguns and the
like. I don't know if they're still doing X-ray lasers or anything
sattelite-borne. I think they're supposed to be completely
ground-based these days.
> Rob Pruden wrote:
I too like the detail you mentioned, but FT excels as simple game of space
combat. You could add additional rules for firing, but I think it might slow
the game down a bit much if you had to roll for sensor locks in addition to
weapon fire. Rolling dies for weapon fire in FT at present in some ways
simulates this already. A roll indicating a miss might be interpretted as
losing a fire control lock.
Of course, if you did this with small ship engagements it might be fun, but
typical FT battles are fleet engagements.
Based on the type of detail you would like to see, you might want to check out
Brilliant Lances which covers about everything you mentioned and then some. It
is highly detailed and provides a realistic approach to space combat.
> Daryl wrote:
I would think any ship designed to carry crew would not be designed to take
maneuvers that would greatly harm the crew. Vehicles today are designed to go
a fair distance beyond(and then some) the limits of an average passenger. If
your crew could only take a max of say, 10 G's without being totally
incapacitated, it is highly unlikely some engineer is going to mount a 40 G
acceleration capable drive in said ship. That is unless the ship is designed
for remote or automated guidance or the engineer is really bad with numbers.
> joachim wrote:
Cool. More research material for wargaming!;)
Date sent: 30-OCT-1996 08:57:32
> I would think any ship designed to carry crew would not be designed to
The EF-2000 is (I've heard) going to be able to perform evasive and
simple aggressive combat maneuvers without the pilot.
Date sent: 30-OCT-1996 16:40:43
> I'm not sure what's survivable (by survivable I mean being able to
> Humans have withstood as much as 45 Gs for fractions of a second
IIRC, it's more like 6G. Anything more than that requires special training, in
the form of breathing exercises, and special equipment helps too.
You'll notice that fighter pilot's don't talk much when pulling G, and their
breathing goes all funny. If they were to breath regularly, they'd be out like
a light.
> Daryl writes:
> I'm not sure what's survivable (by survivable I mean being able to
Humans have withstood as much as 45 Gs for fractions of a second (Apollo, I
think), but obviously not for more than that. The "record" AFAIK for sustained
acceleration without blacking out is 17 Gs for 4 minutes. Of course, that's
the equivilent of the Olympic Record: for us mere mortals, I think 10 Gs is
probably a good assumption. Of course, people aren't going to
be walking around fixing engines and such during 10 Gs. ;-)
My source for the above is "The Starflight Handbook" I mentioned awhile back,
but it doesn't cite who/where/whens for the "records."
Date sent: 30-OCT-1996 17:28:02
> Adam Delafield wrote:
> Cool. It would really be neat to see one fly combat-capable without a
Not quite. Only the pilot's finger on the trigger can make it go 'weapon's
free'. So until he wakes up, it tries not to get shot, and attempts to get in
an advantageous position while it waits for him to wake up.
Again, it's just a roomer at present.
> Adam Delafield wrote:
Cool. It would really be neat to see one fly combat-capable without a
pilot!
> Adam Delafield wrote:
I realize the aircraft still requires a pilot. I was refering to future flight
where there might be vehicles capable of self guidance.