Detecting Weapons' Fire

[swordtart]

Might depend on how leaky the fusion reactor is.

You could coast and manoeuvre the spacecraft on batteries.

That is true. You couldn't use the m-drive though (that has its own signature), but definitely you could run ships systems without using the plant.

What about chemical power plants. These need not be burning hydrocarbons, you could have fuel cells for example burning hydrogen and oxygen and producing water as a by product (that you could then use as fuel for a fusion plant). It is hard to see what emissions could be detectable from such a plant since it generates power electrochemically.

 

[Condottiere]

Concealed manoeuvre drives are contained within ship bulkheads but must be within three metres of the accelerating surface of the ship. Concealed manoeuvre drives add 25% to the tonnage and cost of the drive. The additional tonnage comprises a system that contains and exhausts thruster plate ionisation out of specially designed ports, reducing their detectability to almost nil. Concealed manoeuvre drives cut performance in half (round down), so a ship with Thrust 2 is reduced to 1 and so on. These drives are designed to operate within confinement, so simply removing the outer bulkhead does not add to their performance.


Apparently, heat is your enemy.

 

[Sigtrygg]

Two words - waste heat.

 

[swordtart]

Concealed manoeuvre drives are contained within ship bulkheads but must be within three metres of the accelerating surface of the ship. Concealed manoeuvre drives add 25% to the tonnage and cost of the drive. The additional tonnage comprises a system that contains and exhausts thruster plate ionisation out of specially designed ports, reducing their detectability to almost nil. Concealed manoeuvre drives cut performance in half (round down), so a ship with Thrust 2 is reduced to 1 and so on. These drives are designed to operate within confinement, so simply removing the outer bulkhead does not add to their performance.


Apparently, heat is your enemy.

Do these actually prevent the M-Drive emissions from being detected? As a ship using its m-Drive proves DM+1 to detection per Thrust then being able to move would be a real benefit.

A Thrust 1 concealed drive is already 100% larger than a non-concealed drive (as you need a Thrust 2 drive to get thrust 1). Do you add a further 25%. If it still gives DM+1 to detection you might as well have bought a non-concealed T1 drive.

 

[Condottiere]

Depends on the measurable value of almost nil.

 

[swordtart]

Depends on the measurable value of almost nil.

To be honest when I read Concealed M-Drive I thought it meant the drives themselves were visually concealed (i.e. you could have a really fast ship but make it look like a sluggard). It never seemed worth the effort and so I never read the description in any depth.

It makes far more sense as a component and might well be worth it if conceals the emissions (but the name is wrong for that - Stealth M-Drive would have been more appropriate). Even if that wasn't intended that this is how I am going to read it.

You would probably couple it with regular M-Drives for routine manoeuvres and I'd be looking at a Concealed M-Drive with T1/2 for station keeping and creeping about to reduce the cost and tonnage overhead to a minimum. That would be a very efficient combination for the majority of occasions where Stealth was important. As most stealthing options are Tonnage dependent I can see it being more prevalent in small craft. Something for all those surplus ships boats to have been doing while in service

I think the size of the ship should also be providing some modifier to detection (but couldn't find anything in the rules about that). I cannot think of a single emission source that would not be smaller on a smaller ship (since the amount of weapon fire appears to be irrelevant to the detection DM). The smaller the source the less likely detection. I'd say 1000 DTon is the baseline with a DM-1 for each quartering* of that and DM+1 for each quadrupling. Less than 250 DTon would be -1, less than 63 Dton would be -2 a tiny 3 Dton or less pod would be -4. Conversely a 4000 Dton ship would be +1, 16 kDton +2 etc.

The ability to pursue at speed whilst stealthed is going to become burdensome very quickly, especially given the somewhat marginal benefits of even the most advanced stealth.

Sensors are a bit too good for playable cat and mouse games and much easier to optimise than any countermeasure. Whilst the DM of low grade sensors are poor, Military grade sensors are comparatively cheap and not dependent on the size of the ship. Most sensor ranges are way beyond weapon ranges and closing the distance takes so many rounds that even low chances of detection success can be clubbed to death eventually. We don't have any rules for sensor spoofing and the like. The idea of hiding behind things is hinted at but not really explored. I'd like to see where the orientation of the target was considered as if you ducted emissions in a particular direction you could use the ship itself to mask them to a degree or at least reduce the cross sectional area of the source. These are all things the anyone with ELINT experience could add into their own game, but it would be nice if there were some simple rules in place for the non-specialists.

I'll have to have a dig around JTAS and older editions to see if there is anything to build a rule set on.

* As volume doubles cross sectional area quadruples.

 

[Condottiere]

Stealthification seems somewhat suspect subject in space skirmish.

So, you tend to have to figure it out on your own, whether it sounds plausible.

 

[swordtart]

I think the key aspect is that initial detection requires an active sensor sweep. The logic seems to be that until your RADAR etc has provided a baseline of objects, your more sensitive sensors have no idea where to point. That seems sensible - you scan a torch around the dark room and when you have found a "thing" you might investigate it more closely with your pencil beam high brightness light.

However unless you yourself are running stealthy there is no real incentive not to do an active sensor sweep after you have jumped in. Your jump flash will give you away to any waiting ship and they can go full stealth as they know you are there.

However beyond that initial jump period sensors are very much "here be dragons - possibly". After jump flash someone will need active sensors to find you and at that point any stealth becomes a bit moot. You are both blundering about with your torches flashing in all directions building up a picture as you go.

I used to have a shareware DOS computer game that was all about ships moving through space with limited sensor range (I wish I could remeber the name but it was back in AOL days so that computer is definitely geography). My memory is that it was a lot of fun. Having revisited a number of shareware games and found them less appealing my memory may be playing tricks on me

Might have to break out the old coding skills and make my own

 

[Sigtrygg]

There is still the need for a magic heat sink to make stealth possible, or worse a dedicated heat sink system that takes up a huge amount of your ship.

 

[MasterGwydion]

I think the key aspect is that initial detection requires an active sensor sweep. The logic seems to be that until your RADAR etc has provided a baseline of objects, your more sensitive sensors have no idea where to point. That seems sensible - you scan a torch around the dark room and when you have found a "thing" you might investigate it more closely with your pencil beam high brightness light.

Why would initial detection require active sensors? Have you never played any submarine games? Initial detection is always passive, not active if you don't want to be detected. I personally think that Anti-Radiation weapons should get their bonus when a ship is using active sensors, not just when performing EW actions.

However unless you yourself are running stealthy there is no real incentive not to do an active sensor sweep after you have jumped in. Your jump flash will give you away to any waiting ship and they can go full stealth as they know you are there.

Why would you not have Stealth Jump on that ship? Then no jump flash as long as you don't jump in real close.

However beyond that initial jump period sensors are very much "here be dragons - possibly". After jump flash someone will need active sensors to find you and at that point any stealth becomes a bit moot. You are both blundering about with your torches flashing in all directions building up a picture as you go.

I used to have a shareware DOS computer game that was all about ships moving through space with limited sensor range (I wish I could remeber the name but it was back in AOL days so that computer is definitely geography). My memory is that it was a lot of fun. Having revisited a number of shareware games and found them less appealing my memory may be playing tricks on me

Might have to break out the old coding skills and make my own

There is still the need for a magic heat sink to make stealth possible, or worse a dedicated heat sink system that takes up a huge amount of your ship.

All ships in Traveller have a magic heat sink. That is just how Traveller works. Just like having a magic FTL drive. I don't get why people have an issue with it.

 

[Sigtrygg]

Where is this magic heat sink in the ship construction rules? Where is it detailed?

 

[MasterGwydion]

Where is this magic heat sink in the ship construction rules? Where is it detailed?

Stealth exists in Traveller. Stealth in space can not exist without a magic heat sink. Therefore, magic heat sinks exist in Traveller. It is included inside other things like so many components in Traveller. Could be part of the power plant or it could be in the hull. Could be anywhere. That is how Traveller works in general.

 

[swordtart]

Why would initial detection require active sensors?

Because HG2022 p77 says you do.
"Note that attempting to locate a ship with this level of accuracy requires the use of active sensors."

Have you never played any submarine games? Initial detection is always passive, not active if you don't want to be detected. I personally think that Anti-Radiation weapons should get their bonus when a ship is using active sensors, not just when performing EW actions.

I was talking from the perception of a non-stealth ship arriving and spotting a lurking stealth ship.

Why would you not have Stealth Jump on that ship? Then no jump flash as long as you don't jump in real close.

What does Jump Flash consist of? If it is thermal you can detect it at longer range than EM. Either way you are talking 10,000 - 25,000 km which isn't "real close" (and depending on your sensors you might have a default longer range anyway). Some chance of detection is not the same as no-chance of detection. In the former you can improve the chance of detection with sensor upgrade and higher skill levels. In the latter it just can't happen.

All ships in Traveller have a magic heat sink. That is just how Traveller works. Just like having a magic FTL drive. I don't get why people have an issue with it.

I am still not convinced there is so much heat generated that it cannot be managed, especially in the relatively short time you are transiting. It is not like you are trying to shed heat into a warmer environment. Space is cold.

 

[Sigtrygg]

Because HG2022 p77 says you do.
"Note that attempting to locate a ship with this level of accuracy requires the use of active sensors."

The accuracy is needed for weapon fire, detecting something can be done out to vast distances using passive sensors - every EM telescope is a passive sensor, here in the real world we can observe x rays and gamma rays, UV, visible, microwave, IR, radio from vast distances

Space is cold.

And ships are hot, so they stand out in the thermal, to paraphrase "without space magic there is no stealth in space"

 

[MasterGwydion]

Because HG2022 p77 says you do.
"Note that attempting to locate a ship with this level of accuracy requires the use of active sensors."

This seems to be written by someone who doesn't know the difference between locating and identifying. They are two extremely different things.

It also seems to be written by a person who doesn't know that human eyes are passive sensors. What is their logic? That humans can't shoot people with guns unless the gun as a laser sight or some other active sensor? It is moronic.
The more of this section I read the more I realize whoever wrote it has no idea how any sensors work. How does turning on active sensors only give the enemy a +2 chance to "Initial Detection". If a submarine uses an active ping every single sonar station within miles will know where that sub is at. That is way different than a +2 bonus to your roll. According the chart I can have a -6 Stealth Coating and it entirely negates having an active transponder. Seriously? Needs a rewrite, badly.

I was talking from the perception of a non-stealth ship arriving and spotting a lurking stealth ship.

You won't spot a lurking stealth ship unless they want you to, unless they are a useless low-tech stealth ship vs. a high-TL ship with good sensors.

What does Jump Flash consist of? If it is thermal you can detect it at longer range than EM. Either way you are talking 10,000 - 25,000 km which isn't "real close" (and depending on your sensors you might have a default longer range anyway). Some chance of detection is not the same as no-chance of detection. In the former you can improve the chance of detection with sensor upgrade and higher skill levels. In the latter it just can't happen.

It is gravitic and EM, but the EM is states as only being detectable to the same range as the gravitic flash. So, the range of detection for the gravitic flash is what you need to know.

 

[swordtart]

This seems to be written by someone who doesn't know the difference between locating and identifying. They are two extremely different things.
View attachment 6600
It also seems to be written by a person who doesn't know that human eyes are passive sensors. What is their logic? That humans can't shoot people with guns unless the gun as a laser sight or some other active sensor? It is moronic.
The more of this section I read the more I realize whoever wrote it has no idea how any sensors work. How does turning on active sensors only give the enemy a +2 chance to "Initial Detection". If a submarine uses an active ping every single sonar station within miles will know where that sub is at. That is way different than a +2 bonus to your roll. According the chart I can have a -6 Stealth Coating and it entirely negates having an active transponder. Seriously? Needs a rewrite, badly.

I didn't say it was right

View attachment 6601

You won't spot a lurking stealth ship unless they want you to, unless they are a useless low-tech stealth ship vs. a high-TL ship with good sensors.

My feeling is that you should be able to spot a buffered asteroid ship in an asteroid field, but that doesn't figure on the table at all.

It is only an average check. Even -6 (costing 1MCr/DTon just moves it to Formidable). But that doesn't include any sensor operator skill you only need a skill level of 2 (from skill + stat bonus) so it could easily move into the possible. If the stealth ship literally sits there with all life support off and does absolutely nothing but watch you will ALMOST certainly miss it. But to get even that you need the most tricked out ship you can get. It seems a bit poor that the very best stealth ship could be spotted by any random surplus scout ship with a merely competent sensor op.

As I put forward a small fleet of stealth shups boats could effectively monitor a system and with stealth drives could even move about. Big stealth is probably more expensive than it is worth.

It is gravitic and EM, but the EM is states as only being detectable to the same range as the gravitic flash. So, the range of detection for the gravitic flash is what you need to know.
View attachment 6602

What sensor detects gravitic flash?

 

[MasterGwydion]

What sensor detects gravitic flash?

Good question. The only one I know of has an automatic detection range of a parsec, but is still limited to speed of light, so you'd automatically detect a jump flash one parsec away, but you wouldn't know about it for over 3 years.

Maybe a densitometer?

 

[swordtart]

The accuracy is needed for weapon fire, detecting something can be done out to vast distances using passive sensors - every EM telescope is a passive sensor, here in the real world we can observe x rays and gamma rays, UV, visible, microwave, IR, radio from vast distances.

We are however talking about Traveller rules (which should be based on reality but that is not guaranteed). Generally the things we see in space in the real world are not the size of spaceships but vasty larger and often vastly more energetic.

And ships are hot, so they stand out in the thermal, to paraphrase "without space magic there is no stealth in space"

But they are only emitting IR radiation since there is no conduction or convection. I can block IR radiation with fairly mundane materials. They will be reflected back at me or off to the side, but critically they can be reflected away from a particular receiver. If I wish to block my signature to the main world I just need to put the reflector in front of me. If it is a short distance from the ship or has a vacuum between the "hot" ship and the reflector then it needn't pickup any significant heat from convection or conduction.

I cannot block IR in every direction, but I could collimate it and push it out in a beam (possibly quite a divergent beam) in the direction where detection is least likely (say behind me).

I could also have a cooling jacket around the whole ship with a heat pump to bring the exterior of the ship down close to background levels. I would need to sink that heat, but there is nothing thermodynamically prohibited. If my fuel source is liquid hydrogen then I have a ready thermal sink.

It isn't perfect, but it doesn't have to be.

 

[Terry Mixon]

To be honest when I read Concealed M-Drive I thought it meant the drives themselves were visually concealed (i.e. you could have a really fast ship but make it look like a sluggard). It never seemed worth the effort and so I never read the description in any depth.

It makes far more sense as a component and might well be worth it if conceals the emissions (but the name is wrong for that - Stealth M-Drive would have been more appropriate). Even if that wasn't intended that this is how I am going to read it.

You would probably couple it with regular M-Drives for routine manoeuvres and I'd be looking at a Concealed M-Drive with T1/2 for station keeping and creeping about to reduce the cost and tonnage overhead to a minimum. That would be a very efficient combination for the majority of occasions where Stealth was important. As most stealthing options are Tonnage dependent I can see it being more prevalent in small craft. Something for all those surplus ships boats to have been doing while in service

I think the size of the ship should also be providing some modifier to detection (but couldn't find anything in the rules about that). I cannot think of a single emission source that would not be smaller on a smaller ship (since the amount of weapon fire appears to be irrelevant to the detection DM). The smaller the source the less likely detection. I'd say 1000 DTon is the baseline with a DM-1 for each quartering* of that and DM+1 for each quadrupling. Less than 250 DTon would be -1, less than 63 Dton would be -2 a tiny 3 Dton or less pod would be -4. Conversely a 4000 Dton ship would be +1, 16 kDton +2 etc.

The ability to pursue at speed whilst stealthed is going to become burdensome very quickly, especially given the somewhat marginal benefits of even the most advanced stealth.

Sensors are a bit too good for playable cat and mouse games and much easier to optimise than any countermeasure. Whilst the DM of low grade sensors are poor, Military grade sensors are comparatively cheap and not dependent on the size of the ship. Most sensor ranges are way beyond weapon ranges and closing the distance takes so many rounds that even low chances of detection success can be clubbed to death eventually. We don't have any rules for sensor spoofing and the like. The idea of hiding behind things is hinted at but not really explored. I'd like to see where the orientation of the target was considered as if you ducted emissions in a particular direction you could use the ship itself to mask them to a degree or at least reduce the cross sectional area of the source. These are all things the anyone with ELINT experience could add into their own game, but it would be nice if there were some simple rules in place for the non-specialists.

I'll have to have a dig around JTAS and older editions to see if there is anything to build a rule set on.

* As volume doubles cross sectional area quadruples.

Here is the variable emissions maneuver drive from The Riverland. It's the only stealth maneuver drive I know of.

 

[swordtart]

That is changing the characteristics of emissions rather than reducing them. That might be good for pretending to be another type of ship but by definition that means you have been detected.