Overheated engines broken?

[milosh]

I fail to see the logic in the overheating mechanics of engines. I mean I can somehow live with the fact that they get overheated (though in real life any designer of an engine that overheats before it makes even LK(E)O would lose his job pretty soon) but what I don't understand, why don't they cool down if not used in a 150KM orbit? One would suspect that out of athmosphere it is pretty chilly outside and heat would dissipate quite quickly but no, I was warping through time in the space center for 7d and when I switched back to my rocket, the engine was still overheated exactly the same as 7d before.

Anyway I think this hole overheating mechanic is broken, the engine should begin to cool down the instant it gets shut down, especially when there's no air worth speaking of to cause friction on it. This really got on my nerves yesterday so I eventually decided to disable failure to temperature completely in the debug menu. I then managed to get into the desired 10'000km orbit I needed for a mission and discovered that they finally cooled down, so there seems to be a height where they recover from overheating, does anyone know what this height is?

Edited October 7, 2015 by milosh

[FancyMouse]

a couple of points:

1. Space is cold doesn't mean heat would dissipate quickly. It's actually really slowly at the engine temperature, because the only way you dissipate heat in space is radiation, and it isn't effective at all at just hundreds of degrees. So your whole point is broken in that respect.

2. KSP doesn't track inactive vessel heat, the same way as electricity. This you can blame KSP.

- - - Updated - - -

add:

3. if you time warp up to a certain speed, KSP decides to just compute the equilibrium temperature and assign it to vessel calling it done, instead of calculating it by each time step. That's probably what you're seeing in high orbit.

[Alshain]

Heat dissipation still behaves the same way in space as it does in the atmosphere, except there is no moving air and wind. Air can absorb heat and carry it away in wind, vacuum can not and heat dissipated doesn't move away quickly.

The engine does cool down as soon as it is shut off but if the heat is concentrated in a thick mass it can't dissipate quickly. That's why the radiators are long, thin, and flat. The more surface area, the faster they can radiate because there is more surround space for them to radiate to.

One other thing, the sun is hot. The O-Zone (whats left of it) and the rest of the atmosphere protect us here by diffusing the rays of sun... in orbit, nothing protects you.

The International Space Station has radiators that look much like those in KSP and it doesn't use engines for anything more than slight corrections. Just sitting there in the sun makes it hot (also it has heat generating equipment which KSP doesn't fully emulate beyond the RTG either, your space station won't generate heat from its equipment). If anything the heat system is broken because it is too forgiving (though because it is a game, it should stay that way).

Edited October 7, 2015 by Alshain

[Mastikator]

Vacuum is the best insulator there is since there is nothing to transfer the heat into. That's what vacuum is, nothing. It takes a very long time for things to cool down in space, much longer than on Earth where it is significantly warmer.

[KerikBalm]

a couple of points:

1. Space is cold doesn't mean heat would dissipate quickly. It's actually really slowly at the engine temperature, because the only way you dissipate heat in space is radiation, and it isn't effective at all at just hundreds of degrees. So your whole point is broken in that respect.

2. KSP doesn't track inactive vessel heat, the same way as electricity. This you can blame KSP.

This, except space isn't even cold... a vacuum has no temperature.

Do a temperature scan and read the text in space sometime... KSP is educational in more ways than one

I wish it would also keep track of the last time the vessel was active, and just like with time warp, if its >X hours, it will calculate equilibrium temperature and assign that when you switch back to it.

[FancyMouse]

except space isn't even cold... a vacuum has no temperature.

ummm I always thought "space is cold" refers to the temperature of cosmic background radiation, no?

[milosh]

Actually you are right, I just read this morning in a sci-fi book about the problems of getting rid of heat in space lol. Guess I'm just not used yet to the new additions. Is there a way to cool the engines with radiators? Just to try it out I've slapped some large radiators at the fuel tank and hoped this will help (which it didn't), other radiators that would fit onto an engine (rocket, not jet) I couldn't find.

[nekogod]

ummm I always thought "space is cold" refers to the temperature of cosmic background radiation, no?

Radiation doesn't have a temperature exactly it kind of is temperature.

Temperature is a function of differences in thermal energy, generally something with less thermal energy feels cold, something with more feels hot, however the speed of energy transfer affects the temperature as well a book at 10C will feel a lot warmer than a steel block at 10C because the steel will more readily accept the energy from your hand. Energy always flows from the high energy to low energy system until an equilibriam is formed.

As far as I know there are 4 main ways to do this, conduction, diffusion, convection and radiation.

The atoms of any object above absolute zero (about -273C) vibrate, the hotter they are the faster and more vigorously they vribrate when you touch something your atoms bump into the atoms of the object and will either recieve or impart energy. This is conduction and is one of the fastest ways of heat transfer especially when the temperature difference is large. NOT applicable in a vacuum

Diffusion generally applies to liquids and gases only, if I pour hot water in a bucket of cold water, some energetic atoms will pass on energy but some will also diffuse evenly into the water carrying their energy with them. NOT applicable to solids (ie people, engines w/e) or in a vacuum.

Convection is similar think of something like a warm front of air being forced up over a cold front the energy/atoms all move in bulk. NOT applicable to solids or in a vacuum.

Which just leaves us with radiation. As charged particles (which make up most of everything) vibrate they emit electromagnetic radiation and it is this which carries away thermal energy in a vacuum, it's a very slow drawn out process. As an example a person exposed to the vacuum of space will die within a couple of minutes but will stay warm for something up to around 18 hours.

[Mastikator]

Which just leaves us with radiation. As charged particles (which make up most of everything) vibrate they emit electromagnetic radiation and it is this which carries away thermal energy in a vacuum, it's a very slow drawn out process. As an example a person exposed to the vacuum of space will die within a couple of minutes but will stay warm for something up to around 18 hours.

As a point of comparison, the dark side of the moon gets as cold as -173 Celsius. That's pretty cold. The south pole gets as cold as -73 Celsius. That's a 100 degrees warmer, yet it takes only like 15 minutes for a human body to completely freeze in that location. The same body would remain warm if risen a mere 300km into space. Space is the ultimate insulator

[Red Iron Crown]

Actually you are right, I just read this morning in a sci-fi book about the problems of getting rid of heat in space lol. Guess I'm just not used yet to the new additions. Is there a way to cool the engines with radiators? Just to try it out I've slapped some large radiators at the fuel tank and hoped this will help (which it didn't), other radiators that would fit onto an engine (rocket, not jet) I couldn't find.

Try using the folding radiators. The fixed ones draw heat from the part to which they are attached, and most engines do not permit direct attachment. The folding ones draw heat from the hottest part so they should start cooling the engine as soon as they are extended.

[Retread]

Assuming the same lighting conditions, a human body would freeze faster on the surface of the moon ONLY if it was actually in significant contact with the surface of the moon, because then conduction is also taking place. If not, it is in a vacuum whether it is 300mm or 300km from the surface.

[MarvinKitFox]

Assuming the same lighting conditions, a human body would freeze faster on the surface of the moon ONLY if it was actually in significant contact with the surface of the moon, because then conduction is also taking place. If not, it is in a vacuum whether it is 300mm or 300km from the surface.

Closer to the moon would be *less* cold, as even the coldest darkest side of the moon is still much hotter than deep space background, and is thus radiating (some) heat towards you.

Earth itself is positively toasty, in LEO you are typically 60-80 degrees K warmer than in a very high orbit, simply because of this nice ~290K radiator filling almost half of the sky.

[NathanKell]

I wish it would also keep track of the last time the vessel was active, and just like with time warp, if its >X hours, it will calculate equilibrium temperature and assign that when you switch back to it.

I believe that was mentioned in the dev notes some weeks ago when I was talking about the thermo overhaul in 1.0.5.

[milosh]

Try using the folding radiators. The fixed ones draw heat from the part to which they are attached, and most engines do not permit direct attachment. The folding ones draw heat from the hottest part so they should start cooling the engine as soon as they are extended.

Thank you, I will try this

So only one mistery remains: what to do to prevent overheating rocket engines in the first place? I've build a lifter with a Sailor attached to an orange tank and no matter how little I throttle up so I barely increase in speed during ascend, TWR just slightly over 1, it will always begin to overheat around 70km and be useless around 120km. I tried the same with two LV30 (the 1.25m ones with fixed gimbal), they begin overheating around 80km and get useless (read: 100% overheated) around 140km orbit. How is one supposed to make long trips with such engines that can barely take 5 minutes of burning time, what am I doing wrong?

[KerikBalm]

I believe that was mentioned in the dev notes some weeks ago when I was talking about the thermo overhaul in 1.0.5.

Cool, last week I switched to a vessel I launched back in 1.02 (a nuclear tug and payload), it was still glowing from the 1.02 LV-N heat... my whole Duna flotilla was glowing... I had to go to each one, time warp, then go to the next.... it wouldn't have been good to have switched to them when it was aerobrake time, to find out htey were already cooking (some of the duna intercepts were at quite high relative velocity, dipping quite low into duna's atmosphere).

I'm glad to know I won't have to deal with that any more

Milosh- do you have pics of your craft, or a craft file? I've not encountered problems with mailsails (I assume that's what you mean.. or the skipper?) of LV-T30s.

Are you using any mods?

Edited October 7, 2015 by KerikBalm

[cantab]

Based on what I've observed KSP's "thermal" system is a fundamentally flawed mess. I have zero respect for it and no qualms about enabling the heatproof cheat, not when with that cheat on vessels routinely reach temperatures high enough to start a new freaking Big Bang.

[Goomblah]

Aside from Kraken issues (which generally result in mission failure with or without ignore max temp) I have never had any significant issues with KSP's heating system. The only engines which ever get toasty for me are the Twin-Boar and NERVs. Under what circumstances are you getting these crazy heating issues? (Saying this to both milosh and cantab)

[Kobymaru]

The International Space Station has radiators that look much like those in KSP and it doesn't use engines for anything more than slight corrections. Just sitting there in the sun makes it hot (also it has heat generating equipment which KSP doesn't fully emulate beyond the RTG either, your space station won't generate heat from its equipment). If anything the heat system is broken because it is too forgiving (though because it is a game, it should stay that way).

https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fspaceflight.nasa.gov%2Fgallery%2Fimages%2Fstation%2Fcrew-14%2Fhires%2Fiss014e13293.jpg&f=1

Neat pic! Are those "active" radiators, so is there cooling fluid flowing through there?

This, except space isn't even cold... a vacuum has no temperature.

Well in the statistical thermodynamic definition of temperature, you're right - vacuum does not have particles and therefor temperature.

However, if you put something in vacuum, it will eventually become 4 Kelvin because it's in equilibrium with the cosmic backroung radiation. If we stretch the definition a bit (fully knowing that it's not technically correct), we could say "vacuum has a temperature of 4 Kelvin". In our solar system, it's a lot higher because of the sun.

I believe that was mentioned in the dev notes some weeks ago when I was talking about the thermo overhaul in 1.0.5.

Does somebody have a link for this? I follow devnotes pretty closely, but I seem to have missed that :/

So only one mistery remains: what to do to prevent overheating rocket engines in the first place? I've build a lifter with a Sailor attached to an orange tank and no matter how little I throttle up so I barely increase in speed during ascend, TWR just slightly over 1, it will always begin to overheat around 70km and be useless around 120km. I tried the same with two LV30 (the 1.25m ones with fixed gimbal), they begin overheating around 80km and get useless (read: 100% overheated) around 140km orbit. How is one supposed to make long trips with such engines that can barely take 5 minutes of burning time, what am I doing wrong?

Are you sure it's the engine that causes overheating, and not the atmosphere? If so, building a streamlined rocket helps, and you should keep it pointed mostly prograde (in surface mode!) way up until about 50km.

If you are sure it's the engines, you can only build massive heatsinks to hold enough heat until you get out of the atmosphere, then deploy massive Radiators to get rid of heat.

Also, is it possible that your Physics.cfg is broken? Try repairing your install (if you got KSP through steam) or reinstalling it?

[KerikBalm]

Well in the statistical thermodynamic definition of temperature, you're right - vacuum does not have particles and therefor temperature.

However, if you put something in vacuum, it will eventually become 4 Kelvin because it's in equilibrium with the cosmic backroung radiation. If we stretch the definition a bit (fully knowing that it's not technically correct), we could say "vacuum has a temperature of 4 Kelvin". In our solar system, it's a lot higher because of the sun.

Yes, it is a lot higher because of the sun - even so, calling space cold makes people think that you were freeze really fast in space... because most people think about heat transfer as it occurs on Earth where we have convection going on.

Being in "contact" with space does not cool you down, like being in contact with a cold object will cool you down.

The object cools itself down through blackbody radiation... very slowly in most cases, and the sun is there warming you up, just like on Earth.

-Sure, your not always in the sun, but the cooling rate is pretty low, so its fine

[Seajay]

Lots of cool science stuff here about thermal mechanics.

However, I have never had a problem with this in game. Clusters of solid boosters overheat, anything moving fast through the atmosphere overheats. NERVs get warm (for me they fill up about half their temperature bar after 10 minutes but the hotter they get the faster they lose heat so they settle at an equilibrium there). Nothing out of atmosphere ever actually comes close to exploding. I'd say there is either something odd about your ships (lots of engines clipped together? Big engine attached to a small tank attached to an insulating component? ) or your install or possibly something odd about mine. What are other people's experiences?

Edited October 8, 2015 by Seajay

[milosh]

Sorry I just get back from work and couldn't answer earlier. First off, I don't know why but when I did a flight just yet to take some screenshots the problem wasn't so severe. The engines still got overheated a bit but I managed to get into 150K orbit without it exploding. I then increased AP to well over 1000k and the overheating was completely gone. I thought maybe they released 1.05 but it's still 1.04 so I don't know what I've done differently this time - demo effect anyone? Anyways, as you see in the following screenshot I fly the most basic rocket to achieve a high orbit of 10'000k for my sattelite (needed for a mission). I usually set ascend guidance->show navball to reach 150k orbit and go from there to the desired orbit, flying manually.

The four "boosters" (onion routing to main booster) begin overheating at 30K already - which I can somewhat understand given how close they are together:

The two remaining engines start overheating at 70K:

And are this hot at 200K:

As I said, this flight was much better, when I started this thread my main engine did explode around 130K so I'm guessing that ascend plays a role. Usually I begin my gravity turn around 3-5KM when I've reached ~150m/s and then follow the marker on the navball. The rocket is very stable, no wobbling or anything, it could just use some more RCS when in orbit.

Note also that I've toyed around with the debug menu and in the end didn't know what the original settings were. So I've deleted my physics.cfg to get the default values back and never touched it again. Did I screw up something by doing so or is there any error in my rocket design or how I fly? In any way thank you so much for investing your time in this thread and trying to solve my problem

Edited October 8, 2015 by milosh

[moogoob]

I wonder if this has anything to do with the thermal config of the dual adapter the LV-T 30s/45s are attached to? It looks like it's not passing heat through to the fuel tank. I never get thermal warnings on ascent with either of those two engines, but I never attach more than one to a fuel tank at a time.

[milosh]

It was far worse whan I had only a single Skipper engine attached, those two LV-T30s are an improvement

[edit]: changed "Sailor" to Skipper, dunno why I though it's called sailor lol

Edited October 8, 2015 by milosh

[Seajay]

Here's what I got when I pointed a capsule + orange tank + skipper straight up and left it at full throttle for 50 minutes (with infinite fuel hack)

To get the thermal data Alt+F12 -> Physics -> Thermal -> Display thermal data in action menus.