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Old 08-27-2015, 12:52 PM   #61
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by Anthony View Post
How is a -10 modifier making stealth impossible?
Because the rules using sensors to detect it can be construed, as in post #12 in this thread, to make it not actually very stealthy at all. You'll note I posted after that. But whatever.
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Old 08-27-2015, 12:56 PM   #62
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by safisher View Post
Because the rules using sensors to detect it can be construed, as in post #12 in this thread, to make it not actually very stealthy at all.
Those rules are just a function of space being really empty. Terrestrial stealth technology, on a surface that's perfectly flat, has no cover, and is almost completely featureless, also does not work very well.
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Old 08-27-2015, 12:58 PM   #63
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by Ulzgoroth View Post
I find it hilarious that you're trying to make it other people's fault that they took your strenuous assertions about how it's silly to say stealth in space is impossible to be assertions about reality, not superscience.
I did put "realistic" in quotes. But this is what is really funny Ulzgoroth, because this is what you said:
Quote:
It's not the heat of the reactionless engine. It's the heat of the power plant that allows you to run the reactionless engine.
To which Anthony responded, to a comment about reactionless engines no less:
"Assuming your heat sinks are magical, you can suppress your IR output by quite a lot. The problem is that any realistic heat sink will fail in a very short time scale if used to keep your hull cool."
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Old 08-27-2015, 01:26 PM   #64
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by Ulzgoroth View Post
While I don't see any rules about how that interacts with detection, it would be reasonable to suggest that reactors have reduced heat signature when radiators are shut down. (Rockets probably shouldn't, because of hot exhaust, but that doesn't matter if you're using reactionless.)
This won't affect reaction drives, although reactionless likely would be affected, but I'd probably have closing the main radiators reduce IR signature to +3 (equivalent to auxiliary power) or by -2, whichever gives a lower modifier (and with a lower limit of 0, of course). Rather than the ship having 30 minutes to shut down heat generating components, I'd scale the time to what the vessel's IR signature should be. I suspect the 30 minute estimate would be appropriate for a fission reactor, which is +6, so I'd set that as the base. Every +1 to signature would be -1 step on the SSR table to the time the vessel can operate without the main radiators, every -1 would be +1 SSR. So, a vessel running off a fuel cell would be at +2 to detect (normally +4) and would operate for 70 minutes (probably round it to an even hour) with the main radiators closed or destroyed, while one with a cosmic power plant would be at +3 to detect (normally +12) and would operate for all of 3 minutes.

While on this tangent, I'd say that reaction drives with internal reactors (that is, all the ones that require main radiators) are probably at around -1 to detect with the main radiators closed. They last as long as a reactor with an IR signature 2 steps lower - that is, an NTR would be detected at +5 (normally +6) and would operate for 70 minutes (or an hour) with the main radiators closed.

Last edited by Varyon; 08-27-2015 at 01:40 PM.
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Old 08-27-2015, 02:19 PM   #65
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by safisher View Post
I did put "realistic" in quotes. But this is what is really funny Ulzgoroth, because this is what you said:


To which Anthony responded, to a comment about reactionless engines no less:
"Assuming your heat sinks are magical, you can suppress your IR output by quite a lot. The problem is that any realistic heat sink will fail in a very short time scale if used to keep your hull cool."
I don't know what point you are trying to make, here. Neither of those posts (#17 and 18) are part of the argument about realistic stealth in space that you kicked off in post #19.
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Old 08-28-2015, 04:25 AM   #66
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by warellis View Post
If one has reactionless engines, a refrigerated hull, & some form of heat sinks, how much easier is it to have some type of "stealth" in space?
I think Stealth Hull is supposed to represent things like a refrigerated hull. It'd have to, wouldn't it? Having a low radar profile is nice, but not useful if people aren't using active sensors (and by default, active sensors aren't very useful, especially at the ranges we're talking about). You're trying to avoid detection by passive (EM) sensors.

Of course, when you mention "heat sinks" that makes me think of reactors more powerful than the fuel cells that are your default form of power generation for a typical stealth hull (due to the limitation it has on a maximum IR signature). How would people feel about a heat sink reducing the IR signature of a ship?
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Old 08-28-2015, 08:40 AM   #67
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by Mailanka View Post
Of course, when you mention "heat sinks" that makes me think of reactors more powerful than the fuel cells that are your default form of power generation for a typical stealth hull (due to the limitation it has on a maximum IR signature). How would people feel about a heat sink reducing the IR signature of a ship?
A heat sink doesn't store heat, it dumps it. That is, with reactors, the heat sink (main radiator array) is the source of the ship's IR signature. Shutting down the heat sinks should lower your IR signature, and I posted a system for this upthread.

Spaceships doesn't currently have a system for dumping the heat that is built up while the main radiators are closed (presumably, it's meant to be something like "once you open the radiators again, all built up heat is gone," but that doesn't seem realistic). I'd have the radiators be able to handle dumping more heat than the systems normally generate, allowing them to shed built-up heat while the system is still in operation. If a system was filled to capacity, it would take 30 minutes to dump it in this way. If the system is shut down, the radiators can dump heat in half the time. While dumping heat, the vessel is at +2 to IR or a total of +6, whichever is higher (if the systems are shut down, it's at +6 total to detect if dumping at a normal rate, +8 total if dumping at twice normal).

So, let's say we've got a ship with a fusion reactor (+7 IR). If we want to drop this to +3 by closing off the main radiators, it will last for 20 minutes, +20 minutes per full tank of coolant. If the ship has 4 tanks full of coolant, it can stay in stealth mode for up to 100 minutes. At the end of this time, the ship shuts down its reactor and starts dumping heat as fast as possible. It will take 50 minutes to fully flush the system, and it will be at +8 IR during this time. If it instead opted to flush the system while the reactor was active, it would take 100 minutes and leave the vessel at +9 IR.

As for the sort of "heat sink" you're talking about (and that I originally started posting about, before looking it up and finding out a heat sink isn't what I thought it was), a tank of coolant will serve best there. I'd love a more in-depth system for those, but we don't have one currently. The coolant should last an amount of time based on the IR signature of the system(s) being cooled, as well as number of systems. As a first concept, I'd be tempted to say that coolant should be able to cool a single +6 IR system for an hour. Every +1 to IR signature would be -1 SSR to time, every -1 would be +1. Dumping heat would probably follow the above, although with the coolant normally taking an hour to fill it should take an hour to dump (or 30 minutes if dumping it while nothing else is active). For multiple systems, use the average time and divide by the number of systems. For example, take a vessel with 2 fusion reactors, a fuel cell, and a fusion torch. The reactors are each +7 IR (0.7 hours each), the fuel cell is +4 IR (2 hours), and the fusion torch has an internal footprint of +8 IR (0.5 hours). The average is about 1 hour, so divided by 4 systems that works out to 15 minutes per tank of coolant. Superscience coolant should last longer (potentially a lot longer - a cosmic power plant would fill a tank of normal coolant in all of 6 minutes).
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Old 08-28-2015, 08:52 AM   #68
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by Varyon View Post
A heat sink doesn't store heat, it dumps it. That is, with reactors, the heat sink (main radiator array) is the source of the ship's IR signature. Shutting down the heat sinks should lower your IR signature, and I posted a system for this upthread.

Spaceships doesn't currently have a system for dumping the heat that is built up while the main radiators are closed (presumably, it's meant to be something like "once you open the radiators again, all built up heat is gone," but that doesn't seem realistic). I'd have the radiators be able to handle dumping more heat than the systems normally generate, allowing them to shed built-up heat while the system is still in operation. If a system was filled to capacity, it would take 30 minutes to dump it in this way. If the system is shut down, the radiators can dump heat in half the time. While dumping heat, the vessel is at +2 to IR or a total of +6, whichever is higher (if the systems are shut down, it's at +6 total to detect if dumping at a normal rate, +8 total if dumping at twice normal).

So, let's say we've got a ship with a fusion reactor (+7 IR). If we want to drop this to +3 by closing off the main radiators, it will last for 20 minutes, +20 minutes per full tank of coolant. If the ship has 4 tanks full of coolant, it can stay in stealth mode for up to 100 minutes. At the end of this time, the ship shuts down its reactor and starts dumping heat as fast as possible. It will take 50 minutes to fully flush the system, and it will be at +8 IR during this time. If it instead opted to flush the system while the reactor was active, it would take 100 minutes and leave the vessel at +9 IR.

As for the sort of "heat sink" you're talking about (and that I originally started posting about, before looking it up and finding out a heat sink isn't what I thought it was), a tank of coolant will serve best there. I'd love a more in-depth system for those, but we don't have one currently. The coolant should last an amount of time based on the IR signature of the system(s) being cooled, as well as number of systems. As a first concept, I'd be tempted to say that coolant should be able to cool a single +6 IR system for an hour. Every +1 to IR signature would be -1 SSR to time, every -1 would be +1. Dumping heat would probably follow the above, although with the coolant normally taking an hour to fill it should take an hour to dump (or 30 minutes if dumping it while nothing else is active). For multiple systems, use the average time and divide by the number of systems. For example, take a vessel with 2 fusion reactors, a fuel cell, and a fusion torch. The reactors are each +7 IR (0.7 hours each), the fuel cell is +4 IR (2 hours), and the fusion torch has an internal footprint of +8 IR (0.5 hours). The average is about 1 hour, so divided by 4 systems that works out to 15 minutes per tank of coolant. Superscience coolant should last longer (potentially a lot longer - a cosmic power plant would fill a tank of normal coolant in all of 6 minutes).
Right, yes, I should clarify. I'm thinking of a system that doesn't use radiators, because it's a ridiculous super science space opera, so the question becomes "How do I justify having a powerful reactor without the IR signature?" So far I'd been using fuel cells, but this discussion of coolant tanks (good catch) made me wonder.

So, you argue that the IR signature comes from the radiators, which makes sense. The rules discussing retracting your radiators seems to be discussing them from the perspective of avoiding damage. If I read you correctly, though, it would also lower your IR signature, because the reason we have radiators is that ships don't radiate IR energy well enough on their own.

Thus, for a spooky, super-science, radiator-less ship, the ship radiates heat well enough without an exposed radiator, but you make the case that it could, instead, choose to dump its heat into a coolant system, reducing the IR signature to, say, +3 for 30 minutes, after which the system starts to overheat

(Super science can, of course, mean anything, but if the only assumption we make is "no exposed radiators" does this pass the smell test?)
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Old 08-28-2015, 09:07 AM   #69
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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So, you argue that the IR signature comes from the radiators, which makes sense. The rules discussing retracting your radiators seems to be discussing them from the perspective of avoiding damage. If I read you correctly, though, it would also lower your IR signature, because the reason we have radiators is that ships don't radiate IR energy well enough on their own.

Thus, for a spooky, super-science, radiator-less ship, the ship radiates heat well enough without an exposed radiator, but you make the case that it could, instead, choose to dump its heat into a coolant system, reducing the IR signature to, say, +3 for 30 minutes, after which the system starts to overheat
Sounds about right. Note you shouldn't need a coolant system for the first 30 minutes - if your ship can dump heat without radiators, but can also opt to stop dumping heat (which should be standard for stealth hulls), you can just follow the main radiator array rules, but without having a radiator that can be targeted at all. In that case, the only addition would be that doing so drops the IR signature. Once it stops being stealthy, it can dump the heat into space - which you could handle as I mentioned, just ignore (yep, radiating again, heat reset, continue on), or have it momentarily "flash" in IR by dumping all that heat at once.
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Old 08-28-2015, 09:16 AM   #70
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Default Re: [Spaceships] Heat Signature, Cloaking Device, and Stealth Hull

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Originally Posted by Varyon View Post
Sounds about right. Note you shouldn't need a coolant system for the first 30 minutes - if your ship can dump heat without radiators, but can also opt to stop dumping heat (which should be standard for stealth hulls), you can just follow the main radiator array rules, but without having a radiator that can be targeted at all. In that case, the only addition would be that doing so drops the IR signature. Once it stops being stealthy, it can dump the heat into space - which you could handle as I mentioned, just ignore (yep, radiating again, heat reset, continue on), or have it momentarily "flash" in IR by dumping all that heat at once.
Any thoughts on how one would dump all that IR at once?
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