What is the CEP of traveller beam weapons?

[Dragoner]

Agreed, but that's a different discussion of sensors, jammers, decoys, and deception. Hop on over to the BITS site and look at their mayday and how they treat the sensors jammers and such.

Though in regular CT and HG combat, that would be a good abstract reason for the variable to hit numbers as it is not covered anywhere else. I've seen some of the Mayday stuff according to the rules. I don't think there is any visual LOS going on, really the ranges are kind of abstract as well, even today, aircraft often fight far beyond visual with missiles.

 

[HG_B]

Agree, the 6 g ship gets nailed 100% of the time at short range, but concider if you will the point defense task of shooting down a laser head missile that is evading at 30 g's and is a .2m diameter target at 2 hexes.

I would consider it if such existed in the Trav rules I have. But, point defense would be kilometers and I'd use Sandcasters to shotgun the almost impacting missile.

 

[HG_B]

One should take into account that ships would have active and passive systems to avoid weapons targeting. Aircraft have it now, it's largely unexplored in Traveller, but to assume it isn't there would be illogical. Ships aren't firing at a visual target, they are firing by their sensor readings beyond visual range. Firepower would assume that enough shots would hit to be effective, thus there would be a calculated hit to miss ratio.

In space you have IR sig that can't be masked. There's no invisibility in space. I mean IF, you want to really examine the physics of the matter. Do you?

 

[Dragoner]

In space you have IR sig that can't be masked. There's no invisibility in space. I mean IF, you want to really examine the physics of the matter. Do you?

Depends, you can't have an IR permeable hull if human life is supposed to exist inside it, nor is space one even temp (which is why the hull can't be permeable. This is also not including decoys, flares etc. as physical countermeasures to weapons lock, something which is done now.

You could have a signature of the light of the engine, and IR, but which travels faster? It still is sensor dependent.

 

[aramis]

I forgot one item- my formula gave diameter of the possible movement, not radius.

Agree, the 6 g ship gets nailed 100% of the time at short range, but concider if you will the point defense task of shooting down a laser head missile that is evading at 30 g's and is a .2m diameter target at 2 hexes.

Time delay between the sense data and beam arrival is .4 seconds +fire control delay + turret movement delay. I'll take a guess and call it .41 seconds.
300m/s *.41s/2 = 61 meters. That's a 122 meter diameter of target probability. Looks like you need to fill the skys with beams and try to get lucky.

300m/s * (.41^2)=50.43m diameter deflecton

You simplified wrong. it's: DiameterCEP=Accel*(((Dist in LS for sensor)+(Time to target in seconds)+(time to aim))^2)

Filling in your terms 300*((.2+.2+.01)^2)=300*(.41^2)=300*.1681=50.43

Note that 0.1LS range is ridiculously long for real lasers' focal ranges, and too short for agility to matter much. 0.01s Tta is too short save for a given pulse of and ongoing track & fire. 0.1s for a small weapon already bearing to narrow in, much better.

But remember also: misiles don't have 100% freedom within the potential error in position, either. So the whole sphere of potential position (which presents as a circular cross section) is much reduced for missiles, especially chem or HEPlaR propelled ones, due to off-axis thrust limits not reflected well in game, and the limits of seeking programs.

 

[HG_B]

Depends, you can't have an IR permeable hull if human life is supposed to exist inside it, nor is space one even temp (which is why the hull can't be permeable. This is also not including decoys, flares etc. as physical countermeasures to weapons lock, something which is done now.

You could have a signature of the light of the engine, and IR, but which travels faster? It still is sensor dependent.

No, it doesn't depend. Flares, etc won't work in space with a constantly accelerating target, for reasons that are too obvious to type.

Missiles are either reaction based (HUGE IR sig from exhaust) or maybe grav. In the latter case you have to dump the heat from the PP or quickly liquefy your missile. Either way the IR sig is SO much higher than the surrounding space that it's like like having a bonfire on an open plain at night. There is no way to physically break the passive IR lock unless you destroy the ships sensors.

 

[Dragoner]

No, it doesn't depend. Flares, etc won't work in space with a constantly accelerating target, for reasons that are too obvious to type.

Missiles are either reaction based (HUGE IR sig from exhaust) or maybe grav. In the latter case you have to dump the heat from the PP or quickly liquefy your missile. Either way the IR sig is SO much higher than the surrounding space that it's like like having a bonfire on an open plain at night. There is no way to physically break the passive IR lock unless you destroy the ships sensors.

Unless in 3500 years better ecm is developed, which would only be logical to think there would (this is true for the physical decoys/counter measures as well). As far as temp goes, space isn't one even temp, it could be really hot in a nebula. Sensors would only read where something had been, not where it is because of the relativistic distortion of a moving object.

Thus the abstract nature of the HG combat, making it more complex affects playability in a negative manner.

 

[warwizard]

Thank you Aramis, in this debate I'm first going for agreement about the quality of the problem. We both agree on the quality that the to hit problem is a fundemental issue of physics, and we both agree that there will be some CEP when dealing with physical systems. Worrying about the quanative analysis comes when concidering specific engagement tasks, and developing an excell spreadsheet to automate the calculations and give the overall %chance to miss all shots.

I was using the distance formula 1/2a times t rather than the velocity formula a times t squared.

 

[Enoki]

There's another factor at play here: Duration. That is, how long does the beam actually fire for. If a single "pulse" from a beam weapon has a duration of a second the operator / gunner or fire controls could "pull" or sweep the beam across a target drawing what is essentially an arc segiment that grows in size as the distance from the firer grows. Such an arrangement would make up for some of the inaccuracy at greater ranges although it would also mean less time on a specific point on a target.

 

[HG_B]

Unless in 3500 years better ecm is developed, which would only be logical to think there would (this is true for the physical decoys/counter measures as well). As far as temp goes, space isn't one even temp, it could be really hot in a nebula. Sensors would only read where something had been, not where it is because of the relativistic distortion of a moving object.

Thus the abstract nature of the HG combat, making it more complex affects playability in a negative manner.

You aren't flying around in a really hot nebula. Please study up on temp of space in inner solar system vs. temp of possible targets.

ECM is great but even today doesn't get around physics (the heat IS there radiating). And, do you understand the problems of decoys and constantly accelerating item you are trying to mimic?

IR sensors have the lag of light speed. ~300,000km/sec. The objects aren't moving at close to lightspeed so not sure what you are talking about vis-a-vis Trav missiles & relativity. Pls elaborate.

 

[warwizard]

No, it doesn't depend. Flares, etc won't work in space with a constantly accelerating target, for reasons that are too obvious to type.

Missiles are either reaction based (HUGE IR sig from exhaust) or maybe grav. In the latter case you have to dump the heat from the PP or quickly liquefy your missile. Either way the IR sig is SO much higher than the surrounding space that it's like like having a bonfire on an open plain at night. There is no way to physically break the passive IR lock unless you destroy the ships sensors.

How about using configuration 8 ice asteroid for the hull of a missile/small drone, and keep the thing chilled to 4 degrees K prior to launch, the HEPLAR will use the fuel vaporized off the inner surface for it's reaction mass, and the thermal inertia of the hull should do for the time of flight of the missile. Like using the chill can of the chamelon suits. IR can be masked for short times.

A mean thought: put a TL 16 tractor beam on a missile, that is inside the missile, (point defense model in this case) score a hit with the tractor and watch as the point defense missile and the target pull 1000 g's towards each other. (Acceleration goes infinite (up to limit of power available) as distance goes to 0.)

 

[Dragoner]

You aren't flying around in a really hot nebula. Please study up on temp of space in inner solar system vs. temp of possible targets.

ECM is great but even today doesn't get around physics (the heat IS there radiating). And, do you understand the problems of decoys and constantly accelerating item you are trying to mimic?

IR sensors have the lag of light speed. ~300,000km/sec. The objects aren't moving at close to lightspeed so not sure what you are talking about vis-a-vis Trav missiles & relativity. Pls elaborate.

Battles take place inside Gas Giants, Nebulae, etc. ad infinitum, thus the ambient temp could be anything. Relativistic effects occur at relatively low speeds, after FTL it is anyone's guess, no physics cover that afaik. As far as infrared radiation, how fast does it move? How quickly would it be dispersed? Can it be masked? All of these questions are not answered in the rules and are relatively unknown as far as battles in outer space are concerned. Traveller starships are magic carpets as far as our technological understanding goes, which actually does make sense in itself.

 

[Dragoner]

How about using configuration 8 ice asteroid for the hull of a missile/small drone, and keep the thing chilled to 4 degrees K prior to launch, the HEPLAR will use the fuel vaporized off the inner surface for it's reaction mass, and the thermal inertia of the hull should do for the time of flight of the missile. Like using the chill can of the chamelon suits. IR can be masked for short times.

A mean thought: put a TL 16 tractor beam on a missile, that is inside the missile, (point defense model in this case) score a hit with the tractor and watch as the point defense missile and the target pull 1000 g's towards each other. (Acceleration goes infinite (up to limit of power available) as distance goes to 0.)

There could also be inflatable decoys with a flare telltale to resemble a ship/missile, only on contact would it be discovered.

 

[sabredog]

There's another factor at play here: Duration. That is, how long does the beam actually fire for. If a single "pulse" from a beam weapon has a duration of a second the operator / gunner or fire controls could "pull" or sweep the beam across a target drawing what is essentially an arc segiment that grows in size as the distance from the firer grows. Such an arrangement would make up for some of the inaccuracy at greater ranges although it would also mean less time on a specific point on a target.

I believe that given the length of the combat round is so long that there are probably several shots and the one you are actually rolling for is the one that hits. Which could be part of the reason for randomness in where the shots go unless you are running a Select program in LLB2 combat.

And that also would account for the long range inaccuracy, but probably it's more a function of some leftover wargame thing from Imperium since the rules for that and HG combat are so alike: line up your ships, simultaneous combat, missiles at long range, check for initiative, move to short, beams now get to shoot, missiles are at negative. And its been that way for all the Traveller games and wargames based on it since...

So the whole missiles are long range and beams inaccurate at long - which seems counter intuitive because you'd think missiles at shorter ranges would be less likely to hit or get shot down, while beam weapons at long range would be able to better track their targets and sty on it because differences in dodging would be less effective - but it's the only reason I can think of.

There are, after all a lot of little odd anachronisms like that all over CT (and maybe left over in later versions) because of when the game was made and the primarily wargamer designers who made it. I believe Aramis has pointed this out several times in other areas as probably a reason for other odd eccentricities?

Anyway, that's always been my theory - in '77 lasers weren't that great nor were PAW type devices (I dunno if the bomb-pimped jobs were out yet)...but missiles were getting better and better and drones were being foreseen as the weapon of the future along with longer ranged and smarter cruise missiles.

 

[sabredog]

There could also be inflatable decoys with a flare telltale to resemble a ship/missile, only on contact would it be discovered.

And electronic decoy's, "chase me" decoy drones, heck....by TL-15 I'm sure some sooper-dooper sensors will be around, but there is also always going to be the guys in the labcoats in the room across the hall laboring to make sooper-dooper spoofers to counter and jam them.

Balance people..we just want some reasonable balance of the same battle between protection v. detection that has gone on forever. For example: there are meson screens, and meson sensors are pretty standard for detecting the power plant emissions....so what about a meson shielding screen based on the anti-weapon meson screen for at least that? Then add decoy drones for other things like heat emissions, and so on.

Think combinations of ECM instead of some catch-all/do-all thing and it'll make more sense. And it doesn't have to be perfect -just adds another table to the list of tables various weapons and/or sensors have to get past to hit or detect something, that's all. Give the guys with Electronics and Commo something to do.

 

[Dragoner]

And electronic decoy's, "chase me" decoy drones, heck....by TL-15 I'm sure some sooper-dooper sensors will be around, but there is also always going to be the guys in the labcoats in the room across the hall laboring to make sooper-dooper spoofers to counter and jam them.

Balance people..we just want some reasonable balance of the same battle between protection v. detection that has gone on forever. For example: there are meson screens, and meson sensors are pretty standard for detecting the power plant emissions....so what about a meson shielding screen based on the anti-weapon meson screen for at least that? Then add decoy drones for other things like heat emissions, and so on.

Think combinations of ECM instead of some catch-all/do-all thing and it'll make more sense. And it doesn't have to be perfect -just adds another table to the list of tables various weapons and/or sensors have to get past to hit or detect something, that's all. Give the guys with Electronics and Commo something to do.

I have always assumed that is what the commo guys are doing. IMO, adding another table means a huge amount of playtesting, which is something I've done in designing games, otherwise the complaining never ends.

 

[fusor]

In space you have IR sig that can't be masked. There's no invisibility in space.

Yes, things emit IR (and some things emit a lot of IR, especially fusion reactors) and other radiation, but they can still be "invisible" in the sense that they can be below the resolution of the sensor to pick up by the time that energy reaches them. You still have the inverse square law to deal with (the source is radiating spherically in all directions), and at interplanetary distances the energy from a heat source may well be very hard (if not impossible) to detect.

And "visibility" also depends very much on knowing what direction to look in. Ships do not have full sky-360-steradian sensors. A ship could be "invisible" simply because the ship attempting to detect it doesn't know to look in that direction.

 

[Xerxeskingofking]

As far as infrared radiation, how fast does it move? How quickly would it be dispersed? Can it be masked?

IR radiation is a form of EM energy, and so moves at the speed of light. what you are seeing is incandescent black body radiation, which in turn is a function of the objects temperature.

How about using configuration 8 ice asteroid for the hull of a missile/small drone, and keep the thing chilled to 4 degrees K prior to launch, the HEPLAR will use the fuel vaporized off the inner surface for it's reaction mass, and the thermal inertia of the hull should do for the time of flight of the missile. Like using the chill can of the chamelon suits. IR can be masked for short times.

that would hide the objects heat signiture, mostly, but you'd still have the high temprature fusion exhaust form the HEPLAR that would show up on the scanners (or at least you would if i understand how a HEPLAR drive works). also, a moving object work show up via doppler shift, or any of a dozen other methods of dection (LIDAR, Desomiter, radition form the fusion drive, etc).

I'm not saying it can't be done, but that thiers a lot more vairables than just IR radiation to mask

 

[aramis]

I was using the distance formula 1/2a times t rather than the velocity formula a times t squared.

You've got those backwards.
distance is D=½AT²
Velocity is V=AT.

Note that diameter of possible error is Ed=AT² as it's twice the distance from the no thrust applied point.

 

[fusor]

To illustrate my point - let's say you have an SDB or Patrol Cruiser, which according to TNE (which gives power plant output in watts) has a power plant of 800-900 MW. So let's round that up to 1000 MW, which is a billion watts.

Assuming that all of that power is radiated as radiation, how much energy would be received per square meter at a distance of 1 AU? We're looking for the flux density here, essentially.

The flux density at 1 AU is equal to the power/surface area of a sphere 1 AU in radius. That's 1,000,000,000 W/2.83e23 m², which is 0.00000000000000354 W/m² (3.54e-15 W/m²). Obviously at greater distances the density is far less.

And that's if ALL of that power was emitted as IR radiation - if only a fraction of it is (and IR is only a fraction of the spectrum) then that would be less. By comparison the flux density of the sun (aka the solar constant) is about 1300 W/m² at 1 AU.

Do you think that a 1GW power plant would be detectable at 1 AU by a shipboard IR sensor? Even if you supercool the sensor, the ship carrying it would be emitting way more IR radiation than that puny signal and would swamp it completely. At the very least you'd need to have the IR sensor far from the ship (e.g. on a boom, or as a separate super-cooled probe), and that wouldn't be able to scan the whole sky easily.