Realism Overhaul Re-Entry Question

[ThomJ]

Hi everyone,

I've been having some issues trying to re-enter earth's atmosphere in RO. I have a small orbital science craft that i've been trying to return to earth from LEO (about 200km). I've tried setting my perigee to anywhere between 80km to 40km. The issue is that the probe (and everything directly behind the heat shield) is heating up and exploding, in some cases, even before the shield starts ablating. My first thought is that the shield heats up and the heat is transferred to whatever is touching it, so I've experimented with putting different things between the probe and the shield but I still get the same result. The probe heats up and explodes, due to it's much lower heat tolerance. I'm not an engineer or anything but it would seem to me that a heat shield is supposed to, you know, shield things from heat? I'm I missing something? 

[Human Person]

Just now, ThomJ said:

I've experimented with putting different things between the probe and the shield

Hmm, that usually does the trick. The only other explanation I could think of is that your heat shield is too small and doesn't cover the parts completely. Do you have screenshots?

[ThomJ]

Yes! This is first configuration I tried, with nothing between the shield and the probe. 

This is the second, with a procedural thrust plate (I chose this because of it's high max temp)

And the third config, A second heat shield, albeit without the ablative material. 

And here's an image of it just prior to it's fiery demise 

[Laie]

All I can say.... check F3 after the explosion, to see what blows up first. Might give you some insight.

There's been issues with parts being considered to be wider than the heatshield even though looking at the vessel one wouldn't guess. If that's your problem, you need a wider shield.

[michal.don]

I had the same issue in my RO games. In the end I solved it by putting larger heatshields on my probes. Not very efficient, but solved the problem. Maybe cargo bays could help too.

[Starwaster]

It's natural that you would have problems with trying to protect a payload like that with such a small shield. Your parts are still exposed to convection heating and they will explode. 

The shield should be about twice the diameter in order for those parts to survive.

[ThomJ]

Hey guys, I have an update to this issue, I'm starting to think more and more that it's a glitch. I just tried a modified payload (shield at the front, thrust plate behind it, monoprop tank behind that and then the probe). The shield was bigger, 1.5m, and this time the shield was the first part to overheat and explode and it did so without ablating any material what-so-ever. The thrust plate behind barely started overheating before the shield exploded. Isn't the ablation material supposed to take heat away until it runs out?

On 2/15/2018 at 1:52 PM, Starwaster said:

It's natural that you would have problems with trying to protect a payload like that with such a small shield. Your parts are still exposed to convection heating and they will explode. 

The shield should be about twice the diameter in order for those parts to survive.

Thanks for the info! At least now I understand why things overheat when using too small of a heat shield, but that still doesn't explain why the shield would overheat before ablating...or does it?

Edited February 21, 2018 by ThomJ

[Starwaster]

6 hours ago, ThomJ said:

Hey guys, I have an update to this issue, I'm starting to think more and more that it's a glitch. I just tried a modified payload (shield at the front, thrust plate behind it, monoprop tank behind that and then the probe). The shield was bigger, 1.5m, and this time the shield was the first part to overheat and explode and it did so without ablating any material what-so-ever. The thrust plate behind barely started overheating before the shield exploded. Isn't the ablation material supposed to take heat away until it runs out?

Thanks for the info! At least now I understand why things overheat when using too small of a heat shield, but that still doesn't explain why the shield would overheat before ablating...or does it?

Without seeing the thermal debug data I'm just guessing, but it might be getting getting heat conducted into it from behind. The shield code reads the skin temperature and removes heat from the skin.

additionally, looking at the 1.5m shield on the RO repository, its internal max temp is lower than the skin max temp, so it would (theoretically) be receiving heat into a section it can't shed it from AND which has a lower tolerance. (maxTemp = 1500, skinMaxTemp = 2600).

(Debug Menu ->Physics->Thermal->Display Thermal Data in Action Menus)

The problem with that theory though is that the part conducting INTO the shield would probably have to have a much higher temperature tolerance than the shield, which seems a little bizarre given that it's Realism Overhaul AND Deadly Reentry so the temperature tolerances should be somewhat balanced.

Except... you don't really have Deadly Reentry installed, do you? The shields themselves are Deadly Reentry parts but I don't see the DR icon on your toolbar anywhere so no temperature rebalancing.

[ThomJ]

8 hours ago, Starwaster said:

Except... you don't really have Deadly Reentry installed, do you? The shields themselves are Deadly Reentry parts but I don't see the DR icon on your toolbar anywhere so no temperature rebalancing.

Hmm..very strange. I checked the GameData folder and found DRE in there. I deleted it and reinstalled it anyways and it seems to work as intended! The shield is taking the punishment and ablating like it should, now I just have to work on getting my trajectory right! Thanks again!