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Jon144

1.0.3 Heating oversight

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If this is really a bug I am happy that I reported it so early.

Jet exhaust no longer produces noticable heat. Parts now can withstand ridiculous temperatures. Seperatrons in particular. This does not make sense to me as heat from engine exhaust was just added and existed in seperatron exhaust for far longer. Is this just an oversight because using seperatron exhaust made for some very interesting systems.

Using seperatron exhaust you could make fused cluster bombs by destroying a core unit by burning... releasing several projectiles originally attached to that central part. You could also use seperatron exhaust as a stock weapon for fun.

Was this intended or is this a bug that will be fixed? I like my seperatron heat. I was making a fireworks system using them but now that is off the table.

GcLAqpv.jpg

The above is an example of how exhaust heating does not work in 1.0.3

LxyjsUU.jpg

You would think a mainsail would be able to do the job right? No...

o68L3jh.jpg

You cant really do anything more than this... and it only heats the poor panel to a fraction...

z4xwGmQ.jpg

All of this is especially ridiculous since simply going supersonic can heat many parts far more than several thousand degree rocket engines.

Edited by Jon144
Added example picture

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I believe that this is intentional.

Correct me if I'm wrong (I'm still stuck procrastinating here at work), but surface heating and part heating are now separate. From the changelog:

Thermal:

* 1.0.3 features a revised thermal mechanic to better balance heating/cooling between pods and spaceplanes.

* Parts now have separate internal temperature and skin temperatures.

* Skin temperature is the temperature used for radiation and convection, as well as engine exhaust damage.

* Part internal temperature is increased by modules that generate heat and is used for part-part conduction.

* Part internal and skin temperature also conduct between each other.

Hope that helps.

Edited by DanJourney
I am not good with computers.

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You are correct, and the changelog explicitly notes that heat from exhaust is applied to skin temperature. :)

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That is interesting. I did a test with about x18 packed seperatrons firing at a single structural panel and there was no heat damage. I just expected that so much exhaust should cause some level of heat if just going supersonic can burn some parts off.

In all my tests engines at full thrust do not cause any heat to the object that they are firing on.

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yes, um... it "made sense" to me, that pointing a sepratron... specifically into fuel tanks, would cause them to explode in previous versions. It does not seem right for this to not happen... I am used to that behavior ;)

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blasting several thousand degree rocket exhaust into something and not doing any damage to it is a bit counterintuitive, not to mention removes the semi-often used and extremely kerbal technique of "blowtorch" staging.

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Maybe try enabling the debug options to see what the actual skin and core temps are when you do that sort of thing. Then point a mainsail at the part.

This is really a non-issue for seperatrons, they should be able to separate a stage without exploding other parts. Also, just because you could do something in a previous version doesn't mean you should be able to do it now; if 1.0.x has taught you anything it should be that.

E: Something else to remember is that KSP's parts have grossly inflated maximum temperatures and will not fail as expected IRL. This is because realism is not a priority in KSP.

Edited by regex

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Maybe try enabling the debug options to see what the actual skin and core temps are when you do that sort of thing. Then point a mainsail at the part.

This is really a non-issue for seperatrons, they should be able to separate a stage without exploding other parts. Also, just because you could do something in a previous version doesn't mean you should be able to do it now; if 1.0.x has taught you anything it should be that.

The thing is I can't find any options of the sort in the debug menu. And yes... a small number of separatrons used to separate stages of parts shouldn't cause much heat. But I am pretty sure such a large number should. And this doesn't just pertain to separatrons. This is a bug across all engines.

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Here is a composite before/after, with debug heating values displayed. Jon144: Alt-F12, across the top click Physics button, and in the row of buttons below that: click Thermal, and then check the box marked "Display Thermal Data in Action Menus."

I expect they are correct values, math is math. I am prepared to live with ez-mode sepratrons, but they might be worthy of special casing.

Edit: to clarify, fuel tanks are more delicate than structural parts, might be worthy of special casing. I don't mean to suggest rocket exhaust needs to be "hotter."

Edited by basic.syntax
Added emphasis on fuel tanks

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Here is a composite before/after, with debug heating values displayed. Jon144: Alt-F12, across the top click Physics button, and in the row of buttons below that: click Thermal, and then check the box marked "Display Thermal Data in Action Menus."

I expect they are correct values, math is math. I am prepared to live with ez-mode sepratrons, but they might be worthy of special casing.

So disappointing though... I found so many innovative uses for exhaust heat. Now all rockets are cold.

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Here is the option to enable:

JPis7o8.png

One thing to remember is that a part will attempt to offload its heat onto surrounding parts. I attached the plate to a small cubic strut, which has a very low thermal mass, to avoid the issue of heat spreading. Then I used industrial-grade engine exhaust to heat it up. Here is a picture of the heat right before the engine exploded:

wiuihdG.png

Notice that this structural panel is putting up with over 1000K. That's higher than the melting point of aluminum, and half the melting point of steel. The part config says it has a max temp of 2000K, which is higher than the melting point of titanium. Personally, I should think it would fail far earlier from heat stress.

I then tried with a part that I knew would overheat faster:

wWrY0qd.png

This is a probe core handling 1600K. Seriously, 1600K. That's pretty close to the melting point of wrought iron. A probe core.

The problem isn't really the heating, it's that parts can tolerate a ridiculous amount of heat.

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Here is the option to enable:

http://i.imgur.com/JPis7o8.png

One thing to remember is that a part will attempt to offload its heat onto surrounding parts. I attached the plate to a small cubic strut, which has a very low thermal mass, to avoid the issue of heat spreading. Then I used industrial-grade engine exhaust to heat it up. Here is a picture of the heat right before the engine exploded:

http://i.imgur.com/wiuihdG.png

Notice that this structural panel is putting up with over 1000K. That's higher than the melting point of aluminum, and half the melting point of steel. The part config says it has a max temp of 2000K, which is higher than the melting point of titanium. Personally, I should think it would fail far earlier from heat stress.

I then tried with a part that I knew would overheat faster:

http://i.imgur.com/wWrY0qd.png

This is a probe core handling 1600K. Seriously, 1600K. That's pretty close to the melting point of wrought iron. A probe core.

The problem isn't really the heating, it's that parts can tolerate a ridiculous amount of heat.

Thanks for the help there... Can't believe I missed that.

And that is.... Ridiculous. Are these parts made of tantalum?

In other news I found reentry heating now starts at the very start of the atmosphere. And that is nearly just as ridiculous as this.

Pjbd1Ni.jpg And it is spinning around unstable without SAS...
Edited by Jon144

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http://i.imgur.com/Pjbd1Ni.jpg And it is spinning around unstable without SAS...
vOv

On Earth, small objects not designed for reentry break up at around 70~80km, which is 20km lower than the Kármán line. If we assume that Kerbin's "Kármán line" is 70km, then 45km for atmospheric heating is not strange at all.

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vOv

On Earth, small objects not designed for reentry break up at around 70~80km, which is 20km lower than the Kármán line. If we assume that Kerbin's "Kármán line" is 70km, then 45km for atmospheric heating is not strange at all.

Ah yes I really mis-spoke there. I was really meaning to comment on the level of reentry FX. But I really forgot about how easy those are to fool someone on how much heat there actually is.

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I really hope that Squad fixes this and doesn't just leave us to suffer without engine exhaust heat until the next big release.

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I really hope that Squad fixes this and doesn't just leave us to suffer without engine exhaust heat until the next big release.
Clearly engine exhaust heat works.

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I really hope that Squad fixes this and doesn't just leave us to suffer without engine exhaust heat until the next big release.

It is the ridiculous heat tolerance of parts that needs to be fixed. I guess the ridiculous heat resistant alloys the space program uses is why things are so expensive in KSP.

But then that brings into question how friction can cause so much more heat... Jet fuel must be a large percentage of the atmosphere.

Edited by Jon144

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Clearly engine exhaust heat works.

Thanks for the snarky comment. With engine exhaust heat being ineffective against parts, we may as well not even have it.

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Thanks for the snarky comment.
Always happy to help in that department.
With engine exhaust heat being ineffective against parts, we may as well not even have it.
It's not the engine exhaust heat that's the problem. It could probably stand to come up a bit, but part temps in KSP are the real problem.

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SSME chamber temp: ~3400K (that's the chamber, way hotter than the exhaust a few meters downrange)

Shock temperature on low orbit reentry: ~7000K

Turns out engines just aren't that hot.

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Here's another thing: try this in space where convective cooling is far less of an issue. All these atmospheric tests are letting air wick away the heat from the target faster.

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Isn't the engines exhaust even causing additional convection, eventually even cooling the "object to be heated"? Or is that just the FX implying that?

As for the heat capacities, I'm now somewhat missing an intermediate state between "nothing happens" and "fireworks".

Something as simple as structural weakening. Reducing part strength noticeably as the heat level approaches max temperature, followed by hard function fail for all active functions (including live support....), and only finally explosion.

Getting structural parts to actually "blow up" doesn't even sound right to start with. You would need a huge plasma torch or alike to heat them far enough for that to happen. Breaking apart due to structural weakening and physical force applied sounds far more reasonable.

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regex, I tried a similar setup to yours, but see less than half the heating.

I removed the plate and a launch clamp (not visible) below the Stayputnik in the next test, and heat was slightly lower.

LxVYJHY.jpg

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regex, I tried a similar setup to yours, but see less than half the heating.

I removed the plate and a launch clamp (not visible) below the Stayputnik in the next test, and heat was slightly lower.

How long did you run it?

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Is something conducting the heat away from the part being melted? How about try and direct engine exhaust on a free-standing part held in a crucible?

Or just use one of Jeb's mom's cooking pots :D

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