1.0.3 Heating oversight

[basic.syntax]

How long did you run it?

Most of it. Screenshot was taken with about 10% of burn time remaining. Additionally, I don't see SRB nozzle glow. That could be a sign of something. I restarted KSP, into a new sandbox game, loaded the test rig, and no change. The only mod atm, is KAC.

[regex]

Most of it. Screenshot was taken with about 10% of burn time remaining.

I was using infinite fuel to prove the point.

[basic.syntax]

I was using infinite fuel to prove the point.

ok, I see it now - happy for a repro. But that shows up another interesting tidbit... 10 seconds with infinite fuel on, makes the part hotter than with it off. SRB Thrust curve / profile?

[regex]

ok, I see it now - happy for a repro. But that shows up another interesting tidbit... 10 seconds with infinite fuel on, makes the part hotter than with it off. SRB Thrust curve / profile?

No, it was going for much longer, probably two to three minutes. That is how ridiculously heat tolerant KSP's parts are.

[basic.syntax]

No, it was going for much longer, probably two to three minutes. That is how ridiculously heat tolerant KSP's parts are.

I understand that... and agree, especially in regards to fuel tanks. I think they ought to be a lot more delicate than structural parts. The 'tidbit' I was observing, was that 10 seconds of infinite fuel creates more heat, than 10 seconds of normal SRB operation (no infinite fuel cheat). A thrust curve must be in play, applied over the burn duration. (I notice the part starts cooling toward the end of a normal burn.)

I replaced the Stayputnik with an Oscar-B tank... on normal SRB operation the skin temperature spiked in just a few seconds to 1100, but by half the burn time that drops rapidly. By the end of the burn, it's just below 600. Retrying with infinite fuel enabled, the Oscar-B simply does not want to explode in the amount of time I'm willing to sit there (that's about a minute) while watching the skin temp hold around 1200, and the internal temp rise at a rate of about 5 degrees per second. OK, I let it run while writing this - the SRB explodes first, lol.

[Ruedii]

I suspect that the issue is that part heat tolerance is based on core heat not affected at all by surface heat. Parts should have separate heat tolerances for surface heat and core heat.

[Starwaster]

I suspect that the issue is that part heat tolerance is based on core heat not affected at all by surface heat. Parts should have separate heat tolerances for surface heat and core heat.

They do.

Or they can.

It's just a matter of configuration.

The capability to set maxTemp separately for part (inner) and skin is in there.

Temperature is tracked separately for both sections as well. It will conduct between interior and exterior as well as from interior to interior between separate parts, or between skin/skin of separate parts.

Edit: Also, although you guys are looking at this as a bug, it's really more case of not being able to please everyone. What one person sees as missing behavior, another would describe as unwanted behavior. Just saying...

Edited June 23, 2015 by Starwaster

[cephalo]

It's a shame that they worked so hard to separate heating into different categories, and then forgot to put any in-game consequence to it.

[RidingTheFlow]

Well, there will be always simplifications.

E.g. cluster of working nuclear engines should act like a "mini-sun", actually heating up *everything in sight* purely by radiation - even without exhaust touching them. Now, however, parts only do emit radiation, they never *receive* heat radiation from other parts (like engines).

[benjee10]

Personally just glad reentry is at least kinda dangerous again now.

Edited June 23, 2015 by Red Iron Crown

[Red Iron Crown]

I removed a number of off-topic posts, please restrict the discussion in this thread to the game and not controversial real life disasters.

[Secuas]

You are 'melting' a plate and nothing overheats. I dock and the whole ship melts.

[regex]

I suspect that the issue is that part heat tolerance is based on core heat not affected at all by surface heat.

Core heat is very much affected by surface heat, that's how I got the probe core up to 1600K.

[PB666]

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

Yes but pointing a sepratron at a fuel tank at an oblique angle 2 meters away would blow the tank up in 1 second, that was a little extreme, IMHO.

- - - Updated - - -

To the topic of the OP.

My complaint is that in the VAB right click on the parts, it does not give a relative efficacy of heat dissipation for the parts, Just part strength and looks like a solar panel tracking value (usefullness?)

[Nich]

I would bet that squid is convecting heat away at the skin temp vs air temp while adding heat via skin temp vs exhaust temp. as the part starts to near exhaust temp it dumps more heat to the surrounding air and absorbs less heat from the exhaust.

I would love to see this test in space.

[Hazelnut]

Aww, that seems a shame. I had a 5 minute giggle last night when I tried something and realised that with 1.0.2 heat had consequences.

My Duna Express main tug stage (mk3 cockpit w/tank, 2 outriggers each with LVN) was actually going to struggle to land the small base (2xmk2 crew + sci module) and the rover that were attached to it all the way from Kerbin since it had a TWR of <1 for Duna atmo with them. (yep, forgot to check)

I had a lander designed for Duna with 4 sparks and parachutes. Since I had carried it from Kerbin on the nose of the tug craft I figured why not use its engines and parachutes and hope that they helped more than the weight hindered. The crew module started glowing and after a short space of time explody time, cueing my fits of giggles!! Love those experiences.

FWIW I did land by burning the LVNs 95%+ all the way down from 20km, burning off enough fuel and weight while keeping falling to manageable levels. Was epic. Loved the smoke effects as I neared the surface.

[Jon144]

I would bet that squid is convecting heat away at the skin temp vs air temp while adding heat via skin temp vs exhaust temp. as the part starts to near exhaust temp it dumps more heat to the surrounding air and absorbs less heat from the exhaust.

I would love to see this test in space.

It really shouldn't be that way. As seen the exhaust trail of the engines used project even beyond the structural plates. The heat shouldn't be so far dissipated just a few feet away from the source. The atmosphere should not be cooling the exhaust down so quickly.

The real problem here is how easy heat from engines operating is so much greater than the actual exhaust directly hitting an object. It is implying that all of the heat from the engine pretty much stays within the engine.... which is entirely nonsensical. If you stood underneath a rocket engine in the real world you would be blasted to smithereens. In KSP though it is just a cold gentle shower.

And this was not fixed in 1.0.4

Anyone else trying this test should compare the temperature of the engine compared to the temperature of the object it's exhaust is firing on. It is hilarious. The engine is actually hotter than something it's exhaust is directly blasting.

Edited June 23, 2015 by Jon144

[regex]

It really shouldn't be that way. As seen the exhaust trail of the engines used project even beyond the structural plates. The heat shouldn't be so far dissipated just a few feet away from the source. The atmosphere should not be cooling the exhaust down so quickly.

IRL, the Rocketdyne F-1 had an exhaust temperature around 1700K according to a quick mock-up in RPA. Probably more like 1750K. The RS-25 (SSME) has a nozzle exit temperature of around 1250K (again, from a quick mock-up in RPA). Rocket exhaust, by the time it leaves the nozzle, isn't nearly as hot as it is in the chamber. The further it gets from the nozzle exit, the more the heat can radiate into the atmosphere. If anything, KSP is doing pretty well there.

The real problem here is how easy heat from engines operating is so much greater than the actual exhaust directly hitting an object. It is implying that all of the heat from the engine pretty much stays within the engine.... which is entirely nonsensical.

The heat doesn't stay with the engine, it gets carried away with the exhaust. It's just diffused by the time it leaves the nozzle.

If you stood underneath a rocket engine in the real world you would be blasted to smithereens.

A human being isn't made of heat-tolerant material.

E: The real problem here isn't exhaust temperatures, it's the fact that everything in KSP is made out of a fantastically heat tolerant material.

Edited June 23, 2015 by regex

[Jon144]

IRL, the Rocketdyne F-1 had an exhaust temperature around 1700K according to a quick mock-up in RPA. Probably more like 1750K. The RS-25 (SSME) has a nozzle exit temperature of around 1250K. Rocket exhaust, by the time it leaves the nozzle, isn't nearly as hot as it is in the chamber. The further it gets from the nozzle exit, the more the heat can radiate into the atmosphere. If anything, KSP is doing pretty well there.

That is the thing though. The dissipation into the atmosphere seems very reasonable but I would expect the temperature of the exhaust and the chamber to be pretty much equal at that close of a distance. But it isn't.

But this of course really is not the problem. It is the super-heat tolerant magic alloys.

[Wheffle]

They mine the super element that Kerbin's super-dense core is made out of and smelt it on the alters of the Kraken while they burn their LF+O offerings. A mysterious ancient process that alters the very config file of the alloy.

[Geschosskopf]

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

Yeah, I used to do that intentionally on "fireworks" rockets. Put a few dozen Seps firing into the side of an orange tank. The tank would explode instantly so the Seps were still burning, and they'd go flipping off in all directions like a shower of sparks (which ultimately all hit the ground in a big circle, also exploding). It was my favorite type of fireworks. I'll miss it (sniff).

BUT OTOH, this does make some sense. There are a number of realworld demonstrations you can do at home to show why NOT allowing intense heat on the skin to blow up tanks is actually realistic.

#1. Plastic Drink Bottle

Get a plastic bottle of your favorite beverage and drink 1/2 of it. Now hold the flame of a match or cigarette lighter to the side of the bottle. First put the flame up near the top where there's no liquid inside. Almost instantly, it will melt a hole through the bottle. Now move the flame down to where there's still liquid. Nothing happens.

#2. Wooden Block

Get a section of 4x4 about 1 foot long. Light an acetylene torch, pull the O2 trigger, and hold the flame against the center of 1 side of the block. It will burn a hole into the wood. Now move the torch away from the wood and the wood does not continue to burn.

In both cases, this is the result of specific heat of the solid (or liquid) mass absorbing the heat. In the case of the bottle, the heat was able to pass through the skin and be absorbed without noticeable effect by the liquid, thereby preventing the plastic from reaching its melting point. In the case of the wood, the heat from the area impacted by the flame dispersed into the rest of the block, so that nothing remained at or above its ignition temperature and thus combustion stopped.

[NecroBones]

IRL, the Rocketdyne F-1 had an exhaust temperature around 1700K according to a quick mock-up in RPA. Probably more like 1750K. The RS-25 (SSME) has a nozzle exit temperature of around 1250K (again, from a quick mock-up in RPA). Rocket exhaust, by the time it leaves the nozzle, isn't nearly as hot as it is in the chamber. The further it gets from the nozzle exit, the more the heat can radiate into the atmosphere. If anything, KSP is doing pretty well there.

That is the thing though. The dissipation into the atmosphere seems very reasonable but I would expect the temperature of the exhaust and the chamber to be pretty much equal at that close of a distance. But it isn't.

Lets not forget also that as the gas expands, it cools due to the lower pressure. The heat doesn't have to dissipate anywhere for this effect to occur. It will always be cooler as it exits than it was in the chamber.

[regex]

Lets not forget also that as the gas expands, it cools due to the lower pressure. The heat doesn't have to dissipate anywhere for this effect to occur. It will always be cooler as it exits than it was in the chamber.

I omitted that, thanks for the correction.

[Nich]

yes it is the gas law pV = NRT. and the pressure at the exit of a properly designed engine is the same as the surrounding atmosphere otherwise you get over expansion/under expansion which reduce your ISP. This is directly correlated to your ISP if your nozzle is designed right. I know jet engines run at 50-60 atmospheres but I think an engine like the poodle with 345 ISP would be closer to 150 atmospheres. All I can remember is it is the stagnation pressure of the exit velocity.

[Bomoo]

Agreed. This is an idiotic change, like so many others in the last few updates.