mike wightman
SOC-14 10K
Then how do you explain where the heat goes other than magic box?
T4 Only: Some people say no stealth in space, a discussion.
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mike wightman
SOC-14 10K
How do you deal with waste heat if you don't have huge radiators or do you just ignore it?
mike wightman
SOC-14 10K
So what space magic is used in your game to get rid of waste heat?
Let's assume the pirate ship Xhosa, is landed on an asteroid and is deep within a crevase that does not have a direct line of sight to space. Chilled passive IR sensor drones have been cold soaked then drifted to the surface, and a ship has been detected. The Xhosa has 100 times the thermal radiators than needed for it's installed power plant, and a S/W program that when given a specific direction to avoid radiating it's waste heat towards, routs the heat to the radiators that are on the far side of the ship from the designated direction. In addition it's hull is built like a dewar flask, the inner hull has only one area of contact with the outer hull and that is at the location where it's HEPLAR drive is located, inner hull facing the outer hull is military ultra black and the outer hull facing the inner hull is mirrored so as much of the black body radiation the inner hull emits is bounced back and reabsorbed by the inner hull. now the Xhosa using compressed gas station keeping thrusters drifts away from the asteroid, and once far enough away so that it's ion exhaust will not hit any objects till 2-3 days have passed, moves at .001g to reach a good interception point for it's prey.
OK so this ship has a few things going for it on the IR countermeasures to reduce it's I/R signature: The excess radiators cause it's power output to be treated as 1% of it's normal output -2 to power signature. The cold gas maneuvering thrusters, and tiny ion drive can be used without much of a signature, perhaps only a +.5. And lastly the HEPLAR drive, does not use grav fields, so does not light up the grav sensors, and it's insulated hull also reduces the hull signature by -2 in all except the aft arc. So it's outer hull is NOT 273 degrees K, perhaps only 100 degrees K, which radiates a LOT less blackbody radiation and at a much lower peak frequency, so the lazy sensor tech or poorly written s/w sensor automation program is only scanning for IR signatures much closer to 273 K is unlikley to alert on a 100 K target that is just likley a rock that has been warmed by the sun.
Stealth in space is not needed 360 degrees in a spherical manner, just towards one selected direction. (Knowing the location of system sensor platforms, helps the ship trying to not be detected.)
OK so this ship has a few things going for it on the IR countermeasures to reduce it's I/R signature: The excess radiators cause it's power output to be treated as 1% of it's normal output -2 to power signature. The cold gas maneuvering thrusters, and tiny ion drive can be used without much of a signature, perhaps only a +.5. And lastly the HEPLAR drive, does not use grav fields, so does not light up the grav sensors, and it's insulated hull also reduces the hull signature by -2 in all except the aft arc. So it's outer hull is NOT 273 degrees K, perhaps only 100 degrees K, which radiates a LOT less blackbody radiation and at a much lower peak frequency, so the lazy sensor tech or poorly written s/w sensor automation program is only scanning for IR signatures much closer to 273 K is unlikley to alert on a 100 K target that is just likley a rock that has been warmed by the sun.
Stealth in space is not needed 360 degrees in a spherical manner, just towards one selected direction. (Knowing the location of system sensor platforms, helps the ship trying to not be detected.)
An excellent question. It so happens I hope/expect to be starting a campaign in a couple of weeks. Though I think we are mostly Mongoose I think I will use the CT ranges for starship detection.
The issue of waste heat will likely not come up so I don't expect to have an answer ready. (It is especially true, I think, if you are pointing to a rule as written. Referees rarely need to defend those). Should someone press the detection rules are unrealistic due to waste heat, I will require their player find a smart person in the universe to walk them through the solution as their character is not sure how it all works.
If they seek out a smart person in-universe to explain it then I will come back here for ideas from members like you. I am fully prepared to be told "I told you so", but I don't expect the issue to come up.
If you are using the gravitic based M-Drive in your universe, go with gravitic transfer/ gravitational radiation explanation I mentioned up thread if it comes up. It leverages already existing tech in the universe in a believable way and solves a lot of problems.
This is all well and good if the ship is lying like a spider in a web at an asteroid where it knows a miner might be showing up, so they can ambush them when they arrive. The problem is that, again, still, space is BIG, and that ship will not be able maneuver any reasonable distance at all efficiently toward a target. It'll simply take far to long to be effective.
If you want to sit and wait in the dark, then, sure, maybe, but, man, it better be worth the wait to go to all that trouble just to rob a scrappy asteroid miner.
I don’t think so. You end up with IR streaming out from the ship. Rapid dissipation, that’s nice, but it’s a continuous outpouring of the stuff in a nice big cloud that moves with the ship, doing all sorts of unnatural accel/decel. Reduces the range of detection no doubt, but doesn’t make for stealth.
mike wightman
SOC-14 10K
Umm, no.
The idea is to transfer the energy off the ship as "gravitics radiation due to coupling with the gravitics field the ship's gravitics are coupled with, not as EM radiation of any frequency.
Basically your gravitic systems are your heat sink.
The idea is to transfer the energy off the ship as "gravitics radiation due to coupling with the gravitics field the ship's gravitics are coupled with, not as EM radiation of any frequency.
Basically your gravitic systems are your heat sink.
Enoki
SOC-14 1K
That tiny amount of heat is dissipated into the mass, tons, of the ship. In many ship designs much of the area between the livable portion of the ship and the hull is taken up with fuel tanks. These would have to be some sort of dewar (thermos bottle) so they'd be terrific insulation between the interior of the ship and exterior. Given you have hundreds of tons of ship (mass) the tiny amount of energy coming off a relative handful of vac suits would take forever to even make a tiny difference in outside hull temperature.
Then, it's highly unlikely that any IR sensor at ranges of hundreds of thousands to millions of kilometers could find what amounts to a microscopic speck in the background of space and sense a small rise in temperature from it.
Spinward Flow
SOC-14 1K
{ intensely skeptical look }
Really?
What makes you think that?
Here, I'll even help you.
This ought to be deck plans that most people on these forums will be familiar with.
See those regions marked in grey labeled "fuel" on those deck plans?
Notice how the fuel tankage wraps AROUND the inhabited spaces?
Let's say those fuel spaces need to be loaded with liquid hydrogen (L-H2), which just so happens to need to be chilled to 20ºK.
Let's also say that the habitable spaces need to be warmed up to "room temperature" which we'll call 295ºK.
Trick question. 
Q: What internal space temperature is MOST of the outer hull area in contact with?
A: In this deck plan, most of the outer hull is in contact with the L-H2 (@ 20ºK or less) fuel tanks (outboard), with a very limited area (dorsal and ventral) that is in contact with habitable spaces (@ 295ºK).
Ever heard of a thermos bottle?
Thermal insulation?
What about a heat pump?
As for the question of "what do you do with the waste heat?" ... the short answer is that you (reject) it overboard, dumping it outside the craft.
Now, at TL=7-8, the "best" space technology for doing that is simple radiation, which is "horribly inefficient" and operates as a (more or less) passive system. Presumably at higher tech levels {insert space magic warnings here} it becomes possible to engineer an ACTIVE system capable of dumping waste heat overboard at higher rates than are possible with passive black body radiators. Presumably such engineering would be "built in" to the power plant allocation of tonnage installed aboard space craft, enabling the power plant to "reject waste heat" at a rate necessary to achieve thermal equilibrium in cold (fuel tankage), warm (inhabited volumes) and hot (fusion reactor, HEPlaR maneuvering) regions of the craft's interior.
In other words, a craft with a 295ºK interior inhabited space is NOT NECESSARILY ipso facto going to have a uniform surface temperature of 295ºK at all points of its outer hull, radiating black body heat @ 295ºK in all directions.
For example, a craft with a 295ºK interior that surrounds that interior volume with L-H2 (@ 20ºK or less) fuel tanks as a "buffer" against collisions/incoming damage ... you're going to wind up with a "thermos bottle" type of arrangement ... where most of the outer hull is "touching" a 20ºK (or less) interior space, not a 295ºK interior space. In other words, most of the outer hull will default to being "not all that warm" and will probably be well insulated from the interior fuel tanks. There will probably be a "warm/hot" spot on the hull somewhere (usually the drive bay bulkhead(s)) ... but such features can be angled away from known sensor positions, reducing their signature by means of obscuration (using the craft's hull orientation, relative to the sensor).
Again, I refer everyone reading this thread to my earlier assertion.
If you think that "within sensor radius" means "automatic detection, regardless of context or situation" then you are doing the functional equivalent to believing that simply being TOUCHED by a weapon (any weapon) means either INSTANT DEATH or NO EFFECT as the only two possible outcomes (and No Effect is only allowed for heroes, not for minions).
"LIGHTSAYBAH!"
Enoki
SOC-14 1K
Or, if you want to put waste heat to good use like a military ship might, you collect it into a dewar (thermos) bottle or the like, and fire that overboard periodically. It could even be used as a decoy when necessary. You collect the heat, storing it. Fire it overboard. When it reaches a certain distance from your ship, it releases the heat, and you get a big IR signature that is on nothing. Think of it as a variant of a flare to decoy a missile.
Using something like a 3D printer system means you make containers as you need them, so the system is relatively compact too.
Using something like a 3D printer system means you make containers as you need them, so the system is relatively compact too.
mike wightman
SOC-14 10K
And when the vacc suit runs out of power?
mike wightman
SOC-14 10K
Yes, you can shunt waste heat to a heat sink and then eject the heat sink. Note there has to be something in that Dewar vessel to store the heat.
Trouble is you generate more waste heat doing that, and you now have to remove it. What happens when you run out of Dewar vessels? You pint more, which generates yet more waste heat.
Everything you do on the ship that transfers energy/does work, will contribute to waste heat generation.
In a closed system you will eventually overheat electronics and bake the crew.
So you have to get rid of the heat.
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mike wightman
SOC-14 10K
How do you maintain the liquid hydrogen as a liquid if it is absorbing heat from the power plant, the electronics, every machine and person on the ship?
Why you cool it of course.
Which generates more waste heat.
I don't understand the difficulty here.
A ship is a closed system. In order to remove waste heat you have to radiate it or dump it into a heat sink, and when the heat sink is full you either dump the heat sink, radiate the excess heat, or melt the ship (ok not melt, but you get the idea.).
Enoki
SOC-14 1K
Change the batteries...? According to the rules, they work for 6 to 8 hours. Obviously, if you knew you would be in one longer, you'd have spare oxygen, batteries, etc., handy for swapping out along with suits that could be used that way. You are on a ship and likely sedentary given it's powered down, so you have plenty of time to spare to make those swaps and the things necessary would be right there to do it.
Or, you buy suits that are capable of plugging into the ship and running off the ship's batteries and oxygen supply giving you unlimited time in one for all intents.
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Enoki
SOC-14 1K
Or, you pre-heat the L-Hyd as it is consumed using a heat exchanger to recover some of the waste heat generated like every large power plant on the planet does today. You can also consume some of that waste heat to perform work (power) secondary and tertiary systems knowing it is going to be present. That is, you convert main plant waste heat into other useful energy outputs rather than simply dump it overboard.
The other caveat is "as long as the tanks are full". Drain off fuel, you lose insulation layer.
6-8 hours is "nothing" in space terms. That just gives you time to think deep thoughts on destiny and other philosophical musings.
Also, your ship needs to cool down within those 6-8 hours to begin with to achieve ambient temperature, and that does not happen instantly either. In fact, its particularly difficult in space as you don't have anything handy like water or an atmosphere to carry the heat away.
Then there is the part where you are dumping the heat and making a lovely IR bloom following the ship.
Chill canisters cost and are a consumable.
I assume outrageous cost with stealthing for exotic engineering and costs so something like these solutions would be in play IMTU, but are highly limited and not often encountered.
Chill canisters cost and are a consumable.
I assume outrageous cost with stealthing for exotic engineering and costs so something like these solutions would be in play IMTU, but are highly limited and not often encountered.
mike wightman
SOC-14 10K
So you generate more heat...
it all adds up, and you can only run on batteries for so long.
