UNLIMITED POWER (Reactor Thread (also radiators))

I tweaked the reactor a bit like you suggested and got temps up to 2300 K but at a generating loss approaching 200 MW. Mass and cost increased quite a bit, but the radiator area decrease and delta-v gain were pretty significant as your calculator indicated.



I settled on 2200 K so I could squeeze  a bit more power out of my reactor while still getting the benefit  of hotter radiators.



A further modification with additional tweaking with an outlet  temp of 2000 K generates almost the same amount of power as my initial design and is nearly as efficient as well!

IIRC Amimai and apo-chan did some experiments about a year ago; for warships with armored or redundant radiators, 2500k-2600k is preferable. For civillian ships with paper thin zero redundancy radiators, 2400k was optimal.

By covering the surface area of your hull with radiators you give up the advantages that the current panel radiators have.

In terms of warships you would now take damage to both your radiators and your hull at the same time instead of damage being separated to one or the other in most cases.

Radiator area is now limited by the surface area of your ship. You also get effectively half the radiator area per radiator surface area due to one side facing your hull. At the temps most warship radiators run at( 2000K- 2500K) you would need to insulate the hull facing side of the radiator to prevent heat damage of the hull materials. If you didn't you would suffer vaporization of volatiles( carbons and polymers) softening or outright melting of a fair number of metals, astronomical amounts of additional cooling for the crew compartment and cryogenic fuels, and many more bad effects.

You are also unable to orient the ship in such a way to minimize your heat signature.

You now have to build your radiators individually tailored to each ship or hull type which could greatly increase cost.

Mounting weaponry would be significantly more difficult as you will need to design your radiators with weapons cutouts instead of just plopping them down anywhere there's room. Depending on how tall the radiators are, they may also restrict your field of fire. Additional modification of armament will also be limited. You are no longer able to just whack a hole in your ship and stick a new turret or missile hatch through it. Instead, you will have to remove existing weapons to add new ones.

It would also make docking more difficult because you are blasting heat in all directions instead of just one plane.

The only real reason I see that type of radiator as applicable is when low profile is absolutely critical.

It would probably work better in civilian applications where they run at lower temps and power demands would be much lower.

In terms of the expression, a fine line usually denotes an unclear distinction. §ԾᴗԾ§

After that, an update came that introduced prismatic reactor cores (i.e. higher melting temp limits). That changed optimal points, and now paper-thin radiators also prefer to sit around 2500 K.

This is the reason I stopped providing separate reactor series for 2400 K and for 2500 K; there is no longer a need for the distinction.

I've been messing about with really hot reactors, and thought the results might be worth sharing.

I ended up aiming for a thermocouple outlet temperature of 3100K, since I found that higher temperatures made it very difficult to generate any worthwhile amount of electricity. Even at that temperature, the efficiencies are laughably low (1.4-1.8%).

Firstly, this is a moderately lightweight design which I intended to be used to test whether large fleets of relatively cheap drones with low-power lasers would be effective (answer: not really, but they do look very cool).



After that, I scaled the design up to make something in appproximately the same ballpark as the stock 13.5MW reactor. It's nowhere near as efficient as some of the reactors in this thread, but it appears to quarter the required radiator area compared with the stock version, and makes the radiators easy to hide behind a hull bulge with the new concave armour.



After that I scaled up again into the GW range. At this point the size of the thermocouple becomes truly ridiculous (and it was already pretty bad in the smaller models), and the thermal output begins to exceed that of some countries.



Lastly, I tried to raise the radiator temperature as high as I could while still being able to generate some amount of electricity. I managed a respectable 3290K, although the resultant design is not in any sense practical.



Overall, the trade-offs in material choice and thermocouple size seem to make these designs fairly impractical. In particular, as people had already pointed out earlier in the thread, the low efficiency counteracts much of the savings in radiator mass. However, they are somewhat useful for designing ships where the radiators are totally protected from incoming fire from the front.