mike wightman
SOC-14 10K
You are in a closed system. Anything that does work generates more heat. And the whole point of waste heat is that you can't use it...
T4 Only: Some people say no stealth in space, a discussion.
- Thread starter warwizard
- Start date
OK to the people worried about waste heat, Remember Voyager I and II well these craft have dissimular metal electrtrial system powered by a hunk of radioactive material, there to generate electricity you have two different metals in contact in a hot area wired to the same two metals in contact in a cold area (radiator anyone?) current flows due the differences in temperature in the two areas, one heated by the power plant, the other is radiating that heat. As the heat is transmitted by electrical wiring, it is trivial to have a passive system that connects the 273 K living areas to the radiators mounted on the hull, and to switch to a different radiator or cycle through 100 different radiators to distribute the energy. The current generated is a function of the total area of metals in contact, the voltage is driven by the difference in temperature. As Enoki said this system can generate power to operate other loads, in exactly the way the voyagers do.
mike wightman
SOC-14 10K
The key thing is that there is a temperature gradient and that you are radiating to space.- thermoelectric generation is at best 8% efficient. So you can use it to converts a very small amount of heat to electricity if you have a temperature gradient which means you need something colder than your ship since it is a closed system. So you are back to radiating it to space.
By the way as you use that electricity you generate yet more waste heat...
By the way as you use that electricity you generate yet more waste heat...
The radiating to space can be directional, in fact it is perfered to be directed on the "cold" side of the craft, that is the side away from the sun so there is a greater difference from the hot area to the cold area, There are loads that cannot easilly be neglected on a traveller spaceship that has Liquid Hydrogen, liquid oxyged and liquid water systems that need to maintain their respective temperatures. If you shut down all power sourses and try to eliminate all radiation of heat you will start outgassing H2, O2 excetera, which is yet another signature indicating the presence of a ship, I just assume these thermoelectric systems are allways on and are essential to take the heat from the engineering spaces and dump it overboard. Shutting down the fusion (+?) drives will stop the generation of heat yet the radiators are still on as the hot parts are still transferring the heat to colder parts, and this heat must still be removed or have the cold parts damaged by getting too hot. Flipping the power plant to off is a process that needs several hours to safely accomplish without damaging some of the delicate components. Sitting in your vacc suits and shivering is days away,as it takes that long to bring the drives to room temperature, and the thermoelectric generators/radiators are needed to keep your fuel cold and a few KW can be diverted to life support to maintain the crew in thier vacc suits. In fact a ship with no power generation will eventually end up in thermal equilibrum with it's surroundings if that is hot or cold is related to the system and the ship's position in the system. in a solar system with a functioning star will have a hot side and a cold side (if in view of the star), and the thermoelectric generators will still generate a few KW to keep the crew alive.
Just occurred to me: if you have a nominally-infinite gravitic heat sink, you also have something that could supply nominally infinite energy (not necessarily quickly,, though) using a thermocouple or Stirling Engine.
Enoki
SOC-14 1K
Well, another way to avoid heat would be to convert it to matter. That is, you take energy and create matter from it. Let's assume at some higher tech level that you can take energy like photons and turn it into electrons like some high-tech solar panel would. If you could make protons and neutrons, you turn light into gold or something along those lines. That is, it's almost alchemy but follows the rules of physics.
That takes care of the heat produced.
That takes care of the heat produced.
Condottiere
SOC-14 5K
With enough gravity, you could turn the heat into gold.
mike wightman
SOC-14 10K
It supplies the excess energy to move the ship at the accelerations in the rules as written or to generate an artificial gravity field.
In CT 1EP is 250MW, 250 MW is nowhere near enough energy to move a 1000 metric ton ship at an acceleration of 1g.
So my latest thinking is this.
Traveller has several magic technologies, the trick is to keep them consistent and use them to explain stuff.
TL8 Fusion power
TL8->9 Gravitics - give us null grave modules, lifters, artificial gravity, acceleration compensation and the maneuver drive.
Research into gravitics lead Terrans to invent...
TL9 Jump drive - FTL
TL11->12 Damper and "meson" technology - manipulation of nuclear forces including the strong and the weak.
Gravitics - gravitics is a catch all term for the various technologies that make use of the gravitic coupling interaction.
Gravitic technologies use input energy to couple with a gravity source - this could be a gravity well or even the gravitational wave background. The gravitics can use the gradiant that results from this coupling to generate artificial gravity etc, and even accelerate the ship using energy borrowed from the coupled gravity source (the source loses, the ship gains). Using gravitic technology does produce gravitational waves, but they are very difficult to detect.
A side benefit of gravitics is that waste heat from the ship may be disposed of by radiating it as gravitc waves, with each gravitic based technology being capable of dealing with progressively larger amounts of waste heat. Grav plates radiate the least, m-drive the most.
mike wightman
SOC-14 10K
Waste heat is called waste heat because you can't use it. If it is useful it is not waste.
Solar panels to not turn photons into electrons.
Yes, just because one can see something, it is not logical that someone does see something; no detection system is perfect. This is hard science.
Spinward Flow
SOC-14 1K
So ... the trick is to turn "waste heat" into something "useful" so you don't have to waste it?
Just because WE can't figure it out, doesn't mean that engineers at a higher tech level can't figure it out.
I mean, laser refrigeration WORKS at TL=7.
Rearrange the engineering for it and you can use a refrigeration laser as a heat pump to "dump waste heat" overboard in a specific direction (presumably aft, but details can vary) at high temperatures rather than trying to radiate heat away in all directions using black body radiation (remarkably inefficient). This would then allow you to "aim" your waste heat dumping along specific vectors that shouldn't intercept anyone (or anything) nearby while maneuvering at some distance away from planetary bodies. In congested space, for safety reasons the refrigeration laser would need to be powered down/switched off, obliging traffic to either "maneuver on the clock" and/or maneuver at reduced power (to limit the buildup of waste heat that cannot be rejected overboard safety until clear of the traffic congestion).
An argument could be made that HEPlaR maneuvering systems, while in use, are actually a "heat rejection/dump" of fusion reaction byproducts (namely, 4He, electricity and heat) such that "dumping" the output of those fusion reaction byproducts through the HEPlaR exhaust systems functions as a "net coolant" to the overall starship contained system. Once you view the HEPlaR systems as a "net cooling system" for rejecting heat overboard, all kinds of things become possible for pumping otherwise "waste" heat into that exhaust stream and just dumping it overboard through the HEPlaR maneuver drive ... even at "low thrust" levels ... because the HEPlaR systems can use convection AND conduction to reject "unwanted" heat into the helium exhaust, creating a net cooling cycle via heat pump engineering.
I was watching one of Isaac Arthur's videos earlier on and he touched on stealth and mentioned "Nicoll's Law" so I did a search and came across this (very long) page on the Atomic Rockets site discussing detection and stealth:
projectrho.com
It took me a few hours to read through (it would have taken even longer if I hadn't skimmed some parts). Lots of food for thought in there, but it boils down to:
1) There is no true stealth in space
2) The only way to avoid detection is to have something bigger between you and all possible sensors
3) Or something much hotter behind you
4) Pretend you are something other than you are (transponder spoofing, adjust emissions signature to match apparent vessel type)
Detection - Atomic Rockets
It took me a few hours to read through (it would have taken even longer if I hadn't skimmed some parts). Lots of food for thought in there, but it boils down to:
1) There is no true stealth in space
2) The only way to avoid detection is to have something bigger between you and all possible sensors
3) Or something much hotter behind you
4) Pretend you are something other than you are (transponder spoofing, adjust emissions signature to match apparent vessel type)
Spinward Flow
SOC-14 1K
Invisibility: NO
Camouflage/Spoofing: DEFINITELY POSSIBLE
mike wightman
SOC-14 10K
That is subterfuge in space not stealth in space
Marcatlas
SOC-12
None of that gets rid of the IR signature
Marcatlas
SOC-12
"Directional radiation is hampered because it is not possible to shrink the radiation cone to an angle smaller than about 60 degrees. Attempts to build a system that has a smaller angle than this tend to grow in size very rapidly, as the radiator itself absorbs most of the heat, which must then be re-radiated."
Marcatlas
SOC-12
Yes, when the laws of thermodynamics don't exist much more because possible
Marcatlas
SOC-12
Right. If you are standing on a hill overlooking a pitch dark plain at night and someone 5 miles away is carrying a torch, it is illogical to assume that you won't see it.
What if he is walking away and his body is between you and the torch?
What if the plain extends in 360 degrees around you and he is EAST of your hill and you are looking NW?
The point being made that you so quickly rejected is that DETECTION is not 100% perfect or automatic.
