Invisibility in Space

[rust]

Read some US pilot accounts of the Gulf War, many times visual ID was needed before firing due to IFF problems...

Right, and there was that British fighter downed by friendly fire ...

Another very simple idea the players once used was based on the fact
that a starship can cruise (without acceleration) in any orientation. To
the sensors, a small ship cruising towards an enemy with the broadside
towards the enemy ship look almost exactly like a much bigger ship
cruising with the narrow bow first - the 200 dton merchant looks like a
1,000 dton ship, with five times the number of hardpoints ...

 

[Solomani666]

btw, the F-117 is not invisible to radar from all aspects. A lot depends on where the sensor is looking from. I'm certain that the F-117 is really bright from a couple of narrow angles, but that goes back to the point I made above;

I was referring to the "Hopeless Diamond" not the f117

if you're hard to see from this direction, you're easy to see from another direction.

That is a fallacious statement. Sometimes things are hard to detect from every angle.

You can't be invisible, but you can make it harder for that guy over there to see you.

That is a fallacious statement. Sometimes things are invisible.

.

 

[Ishmael]

Even if "blurry" you are targeted.

No, even if "blurry", you're hit.

Hmm, with a 1 meter TL 7 scope you could see the Space Shuttles maneuver thrusters from Earth if it was at the Asteroid belts. So, a ship with a fusion generator will end up being able to be seen from ~Pluto from Earth. VERY easy with TL 12 passive sensor tech.

You can search the entire 41,000 square degree sphere, with TL 7 cheap retail equipment in ~4 hours. So, 5 X 5 in ~8 seconds. Now, if you are talking about high tech equipment optimized for the task, well, you see where that goes.

Only if you think that a cheap, ground based, TL7 SLR camera is superior to ship based sensors at TL 12.

Actually, the equip is cheap. The scan rates have already been posted. With hi-tech, CHEAP equip, you can scan the entire sphere and still use for collision avoidance. Yes, the IR sensors CAN and are small and still handle the needed wavelengths. Sorry, your arguments aren't backed up by current day science, much less high TL 7 that are in dev.

If the answer is no, then Yay!... perfect knowledge of possible combatants in space and perfect targeting.. no more dice rolling!

You need to reread the CRB as you obviously missed parts of the text

geez...make up your mind
or at least read the question fully.
Can sensors be spoofed or not?
if yes, then the CRB is good
if no, then why bother rolling dice?... even if your blurry, you're hit.

 

[Ishmael]

I was referring to the "Hopeless Diamond" not the f117

That is a fallacious statement. Sometimes things are hard to detect from every angle.

That is a fallacious statement. Sometimes things are invisible.

The Hopeless Diamond was the precursor to the F117
A mockup had a radar return strength of 1/1000th that of the Lockheed D21 drone mockup.

as far as the other statements, please provide references to support your assertions.

 

[locarno24]

If the answer is no, then Yay!... perfect knowledge of possible combatants in space and perfect targeting.. no more dice rolling!

Not necessarily; even if your sensors give you a 'perfect' target picture, you've still got the problem of your target capable of 3G+ a light second away*.

That means that no matter how precise your 'fix', if the target is manouvring evasively at 3G your aim is out of date by about fifteen metres by the time your shots arrive. Step up to something like a viper light interceptor and you're talking nearly a forty metre potential target zone.





* Far from a worst case scenario for traveller ship combat.

 

[DFW]

geez...make up your mind
or at least read the question fully.
Can sensors be spoofed or not?
if yes, then the CRB is good
if no, then why bother rolling dice?... even if your blurry, you're hit.

I never changed my mind (pls reference post where I have)

Because you can detect, why wouldn't you roll dice for attacks?

Pls reread CRB as it appears that you have a DEEP misunderstanding of combat rules.

 

[Ishmael]

Not necessarily; even if your sensors give you a 'perfect' target picture, you've still got the problem of your target capable of 3G+ a light second away*.

That means that no matter how precise your 'fix', if the target is manouvring evasively at 3G your aim is out of date by about fifteen metres by the time your shots arrive. Step up to something like a viper light interceptor and you're talking nearly a forty metre potential target zone.

Its not quite that bad.
You're data is one second out of date, yes... and the 3G ship can be a maximum of 15 meters from the predicted location, and that only if the ship's evasion is constrained to the plane 'normal' to the laser beam; the beam only needs to intersect the ship which makes the targeting solution a 2-d problem. The area of potential locations can be pruned a good bit by the fact that the ship will most likely NOT be doing an unconstrained 2D random walk which allows for some fancy maths to narrow the prediction quite a bit. The ship will most likely be heading somewhere instead of being willing to just skitter about, thus the random walk will be constrained a fair bit.
AND the direction of the vector will be constrain by the ship's agility unless the thrust direction is completely independent of the ship's facing. Otherwise spinning the ship takes time. Probably more than 1 sec. Apply some bayesian maths to all this and it looks about as close to a perfect target for this example as you might get.

If you're using realistic thrusters, fuel usage will prevent much evasion... save your g-turns for evading missiles. So your example is only valid for reactionless drive universes. If the thrust direction is independent of facing, then you've just described the Skylark of Valeron, pretty much.

If passive sensors are good enough to target, then the target won't be evading unless the captain is freekin' paranoid. Then the first shot will hit..perfect target. And it will continue to be a perfect target until the captain decides to do something ( or have the computer program set all the time to automatically evade with no hesitation whenever it thinks an attack is occurring ).

Now for a rant...
Sandcasters used to 'block' lasers or missiles??? WTF? a handful of cubic meters of sand, when dispersed ( dropping its density by insane amounts) in space can affect a missile or laser beam? Ridiculous!

It'd be better to treat sandcasters as chaff and flare dispensers to break target locks and defend the ship by some preventing the ship from getting hit or even targetted, in the first place.

rant off.

 

[Ishmael]

I never changed my mind (pls reference post where I have)

Because you can detect, why wouldn't you roll dice for attacks?

Pls reread CRB as it appears that you have a DEEP misunderstanding of combat rules.

posting number 10

True. However "You can't hit me" stealth is different to "You can't see me" stealth -

No, even if "blurry", you're hit.

you've opined that there is no difference between detecting and targeting as far as countermeasures are concerned. 'Blurry' referes to the effects of stealth and ECM.
You said a hit is certain
Why roll dice if the outcome is certain?, Yet you ask why not roll dice for attacks while knowing that rolling dice exists as a check for success/failure using a set of probabilities; success is not certain.
You can't have it both ways..pls make up your mind.

 

[locarno24]

You're data is one second out of date, yes...

Two seconds - takes a second for the laser shot to arrive where you aimed once you fire. Equally, that's assuming no delay in targeting solutions and weapons traverse.

Note that I'm not saying hitting is impossible; as you noted assuming a complete 'potential target sphere' is unrealistic. However it's easily enough to make targeting a challenge, hence the -1 to -3 (depending on your pilot's skill and how your GM sees the Evade software and dodge reactions as stacking), which is enough to make targeting something to work at.

If passive sensors are good enough to target, then the target won't be evading unless the captain is freekin' paranoid.

True. But then there is no defence, in any logical universe, for "shot in the back of the head by someone you didn't think was a threat". Evasion only matters if we're talking about an onging fight - or at least someone that the enemy has a fair chance of thinking 'is a threat'

If you were shooting at a stationary (or ballistic) target that wasn't attempting to jam, evade, or whatever, then I probably wouldn't make you roll to hit for the first shot unless you were using something that gave away your intention (powering up and traversing something as big and noticable as a bay weapon or lining up a spinal mount is pretty noticable, even if someone isn't explicitely watching your every move.)

Sandcasters used to 'block' lasers or missiles??? WTF? a handful of cubic meters of sand, when dispersed ( dropping its density by insane amounts) in space can affect a missile or laser beam? Ridiculous!

It'd be better to treat sandcasters as chaff and flare dispensers to break target locks and defend the ship by some preventing the ship from getting hit or even targetted, in the first place.

Anti-missile is fair enough. Any missile that's fired from the edge of short range (1250 Km) and is capable of 10g acceleration (standard, non-long range missile) is going to be doing in excess of 11 km/s when it arrives. Collision with even a few grains of sand can be pretty terminal at that point, especially given the fact that the leading edge will be where the seeker heads are.

Anti-laser...yes, there have been enough questions about that in the past. One of the most important ones being how in the name of gods ancient and terrible you "react" to laser fire, which by definition you can't see coming until it arrives, and aren't aware of if it missed you.

I pretty much tend to ignore sandcasters. Lasers are feeble enough as it is, without adding a device that makes them utterly useless. The only time I use them is with pebble rounds to model heavy-calibre autocannons.

 

[BFalcon]

Anti-laser...yes, there have been enough questions about that in the past. One of the most important ones being how in the name of gods ancient and terrible you "react" to laser fire, which by definition you can't see coming until it arrives, and aren't aware of if it missed you.

True, but I've always interpreted that as anticipation through reading the EM bloom of the lasers as they build power just before they fire and escaping light before the main charge - maybe they fire a "targetting pulse" of lower-energy laser light too, either as a side effect or a deliberate attempt to allow the more accurate aiming of the weapon...

 

[rust]

... maybe they fire a "targetting pulse" of lower-energy laser light too, either as a side effect or a deliberate attempt to allow the more accurate aiming of the weapon...

This would make sense in situations where the distance between both
ships is very small or both ships are immobile relative to each other,
but it would not make sense at the usual ranges and speeds of Travel-
ler space sombat - the target is no longer where the "targetting pulse"
hit it when the actual laser attack takes place. The only result would be
to warn the intended target that something bad may happen soon.

 

[BFalcon]

... maybe they fire a "targetting pulse" of lower-energy laser light too, either as a side effect or a deliberate attempt to allow the more accurate aiming of the weapon...

This would make sense in situations where the distance between both
ships is very small or both ships are immobile relative to each other,
but it would not make sense at the usual ranges and speeds of Travel-
ler space sombat - the target is no longer where the "targetting pulse"
hit it when the actual laser attack takes place. The only result would be
to warn the intended target that something bad may happen soon.

Not at all - the scatter of the laser and the analysis of the return would help to determine the vector of the target with better accuracy, including roll...

 

[DFW]

you've opined that there is no difference between detecting and targeting as far as countermeasures are concerned. 'Blurry' referes to the effects of stealth and ECM.
You said a hit is certain

That's a short hand. "able to be hit", targetable. Sorry for the confusion.

ECM doesn't "blur" a target. It screws with a sensor in such a way as to render the target unseen by the sensor or appear to be elsewhere (closer, farther). Sometimes it just overwhelms the sensors completely.

I do think that Sand is a bit ridiculous. Once fired from a maneuvering ship (over the course of seconds) it is left far behind. It might work for a tail chase situation.