Dedicated Radiator Panel parts

[Laie]

Spool-up/down mechanic might be interesting, but would be quite hard to predict the exact burn time because of that. Maybe we would even need to use RCS to correct issues caused by that, not sure if many players would like it...

Somehow I think it would be more agreeable than the current overheating thing. If the spooling logic was similar to Jets (as it probably would be), you could still get your burn right to perhaps 1-2m/s. The remainder is entirely doable with RCS.

I don't think this would be a problem with interplanetary craft. Landers, however, would require a lot more skill (or a Mechjeb update, whatever comes first).

But... sorry if I'm pestering anyone, but isn't this about radiators? And my own post about why I think they're solving a problem we shouldn't have in the first place is now buried deep in the thread.

[Brotoro]

Brotoro, where do you get that stuff? Are there links you could share?

I was looking at some graphs that I had saved as images on my iPad for reference (because the original document is a long PDF that takes a while to download, so it's not handy to quickly look up stuff).

The information comes from the NERVA Detail Specification, Performance/Design and Qualification Requirements document.

Lots of fiddly bits and requirements. The nice diagrams and graphs are in the last half of the document.

Oh...and the engine operating temperatures are specified degrees Rankine (the absolute temperature scale that uses Fahrenheit-sized degrees). Ah, the bad old days.

- - - Updated - - -

But... sorry if I'm pestering anyone, but isn't this about radiators? And my own post about why I think they're solving a problem we shouldn't have in the first place is now buried deep in the thread.

And I apologize for the tangent. But I love KSP because it gives us the opportunity to teach people about rocketry, so I'm sad that Squad is getting this particular aspect of rocketry wrong, and making the nuclear engine have crazy overheating. So I like to take the opportunity to correct people's misconceptions about how a solid-core NTR operates. Maybe Squad will even take notice.

So...yes, radiators would be interesting. Temperature control is a very important aspect of spaceflight. But having to add radiator parts to solve a problem that shouldn't exist in the first place annoys me.

(And these details about NTRs gets put in just to explain WHY it annoys me, and it's not just because of rage at a change in the program).

Edited May 7, 2015 by Brotoro

[Kuu Lightwing]

Well, they are getting better - at least now it doesn't use oxidizer

Sorry for derailing, Laie. Now, time to bring that post back:

Coming late to the party... Yesterday, I spent an hour watching how heat flows around my vessel and... well.

Within a three minutes after igniting the Nerva, the whole vessel was insanely hot, even the most remote parts were over 1000K. IIRC, at that temperature the paint should come off, the metal should be glowing red, and the fuel in the tanks should long be gone. Shouldn't the whole thing radiate like mad? I'm expecting hundreds if not thousands of Watt/squaremeter. Likewise, I didn't calculate how much heat per thrust a LV-N gives you, but I expect it to be preposterous.

In a nutshell: I don't think we need a heatsink, we need much reduced heat generation or much better radiation or something. Or maybe even a whole new heat system. The current one seems credible as long as we're talking about re-entry heat (which probably is superficial); but a hot engine boiling the vessel through and through until batteries pop at the far end, well, that's not even wrong. ©

I don't know how 60kN of thrust translate into Joule or Watt, but I wonder if there isn't more energy going into the vessel than out of it.

When I saw DasValdes playing with drills and ISRU on the stream, I instantly started to feel that heating your entire spacecraft to 700K is just wrong... ISRU stuff no longer heats up that much, but with NERVA point is still the same. I doubt astronauts would be very happy sitting in a can that's red-hot... So, yeah, that doesn't really feel very realistic. I don't even know how to fix that without scrapping the entire heat model they were working on quite hard (I guess)...

[Jappards]

I agree we need some sort of cooling system, but I think we should have both active and passive cooling:

Radiators: these don't require any kind of electricity, but are slow.

Thermoelectric coolers: These require electricity, but are a lot faster.

[Laie]

When I saw DasValdes playing with drills and ISRU on the stream, I instantly started to feel that heating your entire spacecraft to 700K is just wrong... ISRU stuff no longer heats up that much, but with NERVA point is still the same. I doubt astronauts would be very happy sitting in a can that's red-hot... So, yeah, that doesn't really feel very realistic. I don't even know how to fix that without scrapping the entire heat model they were working on quite hard (I guess)...

Thanks for backtracking. As said before, that heat system isn't bad when it comes to re-entry heat. The problem is that they're using the very same system for overheating parts, where it's just ridiculous. I'd suggest to limit heat to reentry for the time being, and keep heat-generating parts (as well as heatsinks) off the table until a better heat model can be devised.

[Red Iron Crown]

I agree we need some sort of cooling system, but I think we should have both active and passive cooling:

Radiators: these don't require any kind of electricity, but are slow.

Thermoelectric coolers: These require electricity, but are a lot faster.

Where would the heat removed from the thermoelectric cooler go? Most cooling systems on Earth don't remove heat so much as move it somewhere else, on a spacecraft in space there is nowhere else to move it; it's radiate it away or keep it. (The only exception would be total loss cooling, in which the heat is moved into something and that something is jettisoned. Useful for engines but not much else.)

Thanks for backtracking. As said before, that heat system isn't bad when it comes to re-entry heat. The problem is that they're using the very same system for overheating parts, where it's just ridiculous. I'd suggest to limit heat to reentry for the time being, and keep heat-generating parts (as well as heatsinks) off the table until a better heat model can be devised.

I think the heat model is fine (and quite realistic in the way heat moves around and is gained/lost), it's just that rocket engines produce too much. Real rockets shed heat with their propellant.

Edited May 7, 2015 by Red Iron Crown

[Laie]

Where would the heat removed from the thermoelectric cooler go? Most cooling systems on Earth don't remove heat so much as move it somewhere else, on a spacecraft in space there is nowhere else to move it; it's radiate it away or keep it. (The only exception would be total loss cooling, in which the heat is moved into something and that something is jettisoned. Useful for engines but not much else.)

The point is that a cooling system could heat up the radiator, rather than wait for heat to crawl into it on it's own. You get a cool vessel on one end, and a hot radiator at the other.

I think the heat model is fine (and quite realistic in the way heat moves around and is gained/lost), it's just that rocket engines produce too much. Real rockets shed heat with their propellant.

(repeating previous post)

The current model looks good and seems credible in the context of re-entry heat, where one naturally assumes that it's surface temperature. 1200...1500...1700K on re-entry? No problem with that. I'm sometimes annoyed at how the heat quickly spreads throughout the vessel, reaching every nook and cranny even on the leeward side, but still, it's not bad.

However, in the context of parts running hot and dumping their heat into the vessel, this breaks down. Completely. If it says "this tank has 1200K" I assume that this is not only the surface, but the whole tank and it's contents.

Maybe it would help if parts had a surface and a core temperature. Maybe it would help if conductivity was lower, allowing you to have sections of your vessel that won't run hot (though others would, of course, grow even hotter). I don't know, and perhaps this is not the thread for it. But I do know that the current system is fundamentally flawed, and papering it over with a radiator part would only make it worse.

[Brotoro]

Where would the heat removed from the thermoelectric cooler go? Most cooling systems on Earth don't remove heat so much as move it somewhere else, on a spacecraft in space there is nowhere else to move it; it's radiate it away or keep it. (The only exception would be total loss cooling, in which the heat is moved into something and that something is jettisoned. Useful for engines but not much else.)

The Apollo Lunar Module's electronics were cooled by evaporating a water-glycol mixture.

And, yes, other than that, an active cooling system is going to need a radiator, ultimately (unless we are talking about a heat pump system that's meant to move heat quickly to other parts of he ship...which effectively become the radiators).

I think the heat model is fine (and quite realistic in the way heat moves around and is gained/lost), it's just that rocket engines produce too much. Real rockets shed heat with their propellant.

Agree. The engines are dumping too much heat into the ships.

[Laie]

Agree. The engines are dumping too much heat into the ships.

But if they dump any less, where's the point? You have to reach a temperature where at least some parts are at risk of exploding... and these temperatures are designed for (superficial) reentry heat. If the engine doesn't produce enough heat to endanger any parts, you can as well leave it out entirely. Which is what I'm suggesting.

Edited May 7, 2015 by Laie

[Sky_walker]

Would be good if heat management would be... you know... a thing. So you would need to have thermal radiators or your bigger space stations, ships, etc.

NASA on ISS radiators