[WIP] Nert's Dev Thread - Current: various updates

[Nertea]

Okay, I adore the heatpipe texture and model

Getting some weeeird effects though. Took a MX-4 with 6 conformal radiators to space. One there, and the reactor offline, they would happily cool the reactor down all the way to 4 K, which is equal to ambient. The fact that I sandwiched it between double insulators made the radiator's job that much easier.

https://dl.dropboxusercontent.com/u/44754370/screenshot51.png

But then - you'd think that at 4 K, the heat transfer would stop, right? Because the reactor is clearly not getting any heat input aside from the conductive backflow from the radiators, as you can see in the image. But no, the radiators keep heating up at full speed. They're at about 600 K now, even though they were barely over 400 K when the reactor reached 4 K! It seems like there's an infinite reservoir of heat to draw from a part that sits at minimum temperature. Inside the atmosphere, when the radiators keep the reactor at ambient, this does not happen.

I watched for a while and the radiators went all the way to 1048 K, at which point the rad flux + cond flux outgoing was equal the internal flux incoming.

With the reactor running at 100%, the radiators went up to 1065 K, a mere 17 K more. The reactor itself rose from 4 K to 390.7 K - nowhere near a critical temperature. Note, again, that this was double-insulated from the rest of the ship, which worked exceedingly well. The rest of the ship did not contribute anything whatsoever towards cooling the reactor.

Don't have more time than this to test today, I'm afraid. More tomorrow.

Mmm, I suspect what's going on is 100% transfer at 4.000001 K and then no transfer, then transfer at the next frame... etc. Will have to work around that.

Wow Nertea, you're like the superhuman blend of hard work and talent.

Sorry if it might sound indiscreet, but how are things holding up on the financial end? I see you have a Donate button, but there's been little discussion of it.

Donations are always welcome, but not necessary .

Nertea,

It may be helpful to include a ModuleManager file that adds nuclear reactors and decaying RTGs to the list of modules recognized as power sources for contracts. I believe this should work:

@Contracts
{
	@MODULE_DEFINITIONS
	{
		Power = ModuleRadioisotopeGenerator
		Power = FissionReactor
	}
}

Great idea, implemented.

I think tank switchability is better left to Cryo Engines. Without them there is little use for it, and you already bundle IFS with that mod.

So is the generator separate from the core now in terms of warmup then?

You probably know, but the description for the small universal is incomplete.

Heat pipe looks exactly how I thought it would!

The Tau is a nice addition, is that what you would recommend for use in atmosphere?

I'll try and test more, still getting used to the new system. I find myself wishing for a 3m conformal.

Edit: is the heatpipe meant to shunt to a part with radiators attached, or the rads themselves? Also it's kinda hard to use vertically along a stack. With fuel lines you could always stick a cubestrut or something in there to let it reach further, but with heat the part either insulates the engine/reactor from the pipe or explodes due to overheat.

True enough maybe I'll leave that out. There is no "core" per se. The Tau is for use in atmo, yes, eventually there will probably be stack radiators and stuff. Re stacking, you should be able to use a cubestrut, which has a highish temp tolerance. The pipe will draw from that, but a pipe (unlike a fuel line) has a fixed capacity per line, so you might need more than one. I plan on providing heatsink parts that have handy protrusions for pipe attachments, but they won't be in the release, no time for models.

[Streetwind]

Mmm, I suspect what's going on is 100% transfer at 4.000001 K and then no transfer, then transfer at the next frame... etc. Will have to work around that.

I don't believe that's what's going on. I know what behavior you speak of, I've seen it happen with heatpipes when testing on the launchpad. As soon as ambient temp is exceeded it transfers a single large burst and then waits for several frames for the temperature to come back up over ambient. The result is a very visible, high frequency flickering in the internal flux and part temperature readouts on both parent and target parts.

But when doing that test in space, there was no flickering at all. Also, the only source of heat flowing into the reactor at the time was the conductive backflow from the hot radiators. Since the radiators are constantly removing heat from the system, the end result should be that the radiators cool down over time. But I saw the opposite: they kept heating up, at full speed, as if they had an infinite amount of heat to draw from.

[Psycho_zs]

I've tested new Deadly Reentry, it breaks things, especially radiators (wraps them into skin). I've asked how to properly exclude things from this, will repost here.

[Streetwind]

That's unfortunate

Nertea: just had an idea. The easiest way to solve the unlimited heat at 4 K issue would probably be to simply not let the radiators cool down the ship all the way to 4 K (I mean seriously, that's just silly regardless of how you look at it). Just give 'em a value, like 200 K, below which no heat transfer happens no matter what. Shouldn't be more than a single IF/ELSE statement, right? </amateur>

EDIT: and I just re-read your suggested implementation post, and noticed you stated that radiators are supposed to throttle if their temperature gets much higher than that of the parent part. There was clearly no throttling going on in my test. This could be either because the throttling is not working, or because the radiators are actually believeing they're attached to something infinitely hotter than themselves if the parent part is at 4 K.

I can probably test this with relative ease once I get home...

Edited May 13, 2015 by Streetwind

[Starwaster]

Regarding Deadly Reentry:

That's going to be problematic in the next update because the modules will be added programatically.

If I'm understanding the problem correctly you're getting unwanted heat buildup?

One suggestion would be to set skinHeatConductivity in the ModuleAeroReentry to 1 - that will allow an unimpeded flow to the surface.

Another possibility is that we figure out some method of exemption. If the radiator has a module that's unique to it, I could use that to exempt it from having anything added to it by DRE

[Psycho_zs]

I tried this:

@PART
[*]:HAS[@MODULE[ModuleGenericRadiator]]:FINAL {
    !MODULE[ModuleAeroReentry]
}

But it didn't do anything. Looks like DRE taps into physics via ModualrFlightIntegrator.

By the way, ModualrFlightIntegrator might have some potential worth investigating for NFT and it's reactors.

[Streetwind]

Another possibility is that we figure out some method of exemption. If the radiator has a module that's unique to it, I could use that to exempt it from having anything added to it by DRE

Could you support a simple blacklist? Like, Deadly Reentry comes with a blacklist file, and any part entered into it would be excluded?

Or alternatively, a dummy module that people can add to their part configs (using ModuleManager even if necessary) that will make DR recognize the part as requiring to be excluded?

Those solutions would cover all bases that might potentially pop up, not just Near Future.

By the way, ModualrFlightIntegrator might have some potential worth investigating for NFT and it's reactors.

Could you describe in what way?

[Nertea]

That's unfortunate

Nertea: just had an idea. The easiest way to solve the unlimited heat at 4 K issue would probably be to simply not let the radiators cool down the ship all the way to 4 K (I mean seriously, that's just silly regardless of how you look at it). Just give 'em a value, like 200 K, below which no heat transfer happens no matter what. Shouldn't be more than a single IF/ELSE statement, right? </amateur>

EDIT: and I just re-read your suggested implementation post, and noticed you stated that radiators are supposed to throttle if their temperature gets much higher than that of the parent part. There was clearly no throttling going on in my test. This could be either because the throttling is not working, or because the radiators are actually believeing they're attached to something infinitely hotter than themselves if the parent part is at 4 K.

I can probably test this with relative ease once I get home...

Don't worry about it, I fixed i

Regarding Deadly Reentry:

That's going to be problematic in the next update because the modules will be added programatically.

If I'm understanding the problem correctly you're getting unwanted heat buildup?

One suggestion would be to set skinHeatConductivity in the ModuleAeroReentry to 1 - that will allow an unimpeded flow to the surface.

Another possibility is that we figure out some method of exemption. If the radiator has a module that's unique to it, I could use that to exempt it from having anything added to it by DRE

All radiators have ModuleGenericRadiator.

[Psycho_zs]

Could you describe in what way?

Judging from description, it allows tapping into heat model without conflict between mods.

[Nertea]

Minor bugfixes:

X.4.11

• Finished textures for 1.25 and 2.5 m insulators
  
• DDS texture for heat pipe
  
• Added Fission Reactors and RTGs to the contract power sources database
  
• CTT patch for HeatControl parts
  
• Fixed cut off description for XR-500 radiator
  
• Fixed infinicool bug
  

Left to do for me is texture the 3.75m insulator and model/texture the 0.625m one. Hopefully by then we'll have the balance worked out.

[Starwaster]

I tried this:

@PART
[*]:HAS[@MODULE[ModuleGenericRadiator]]:FINAL {
    !MODULE[ModuleAeroReentry]
}

But it didn't do anything. Looks like DRE taps into physics via ModualrFlightIntegrator.

By the way, ModualrFlightIntegrator might have some potential worth investigating for NFT and it's reactors.

You didn't close it with a pair of {}

@PART
[*]:HAS[@MODULE[ModuleGenericRadiator]]:FINAL
{
	!MODULE[ModuleAeroReentry]{}
}

It's on you guys now to make sure that can still burn up

[kiwiak]

I've tested new Deadly Reentry, it breaks things, especially radiators (wraps them into skin). I've asked how to properly exclude things from this, will repost here.

I tried it today too, seems like we have same issue, radiators keep heating by themselves until they explode. (i played pre 4.11 though)

[DerekL1963]

Did some testing of NFEX_4_10 with various configurations of LV-N's and the monster LV-NB (from KSPX) last night. Seems to be a reasonable balance, the radiators are heavy enough to give a noticeable performance hit (accounted for easily enough by either attention to your design or MOAR BOOSTERS!!), but perform well enough that you don't need to spam them in mass quanta to keep temperatures within a decent range for any normal burn length.

[Streetwind]

Okay, testing comments time!

Left to do for me is texture the 3.75m insulator and model/texture the 0.625m one. Hopefully by then we'll have the balance worked out.

What about the heat exchanger part, the one that conducts really well? It's still a 2.5m placeholder.

Radiators should display their heat transfer capabilities in the VAB, instead of (or in addition to) the estimated total cooling capacity. I'm not even sure that figure is necessary anymore.

On/off button for radiators, like the heatpipe has one?

Thermal mass of parts intentionally skewed? 880 on KP-XL PIT (1.1 t) vs. 98 on mx-4 reactor (2.3 t) seems a bit odd.

After spending a long time at 100% reactor and engine load, with my radiators nice and heated up, I reverted to the VAB. Made a change (removed the insulators), and launched again. Upon arriving on the launchpad, all six radiators immediately exploded "due to overheating", and the remaining parts of my vessel had large amounts of heat in them.

Reverting to VAB again and launching again --> no problem at all.

I have since not been able to reproduce this at all. Anyone ever seen that kind of thing?

How the heck does KSP calculate conductive flux?! o___o

Consider this ship: small nose cone, mk1 command pod, erg-20 argon tank, mx-4 reactor / 6x GR-4 radiator, KP-XL PIT

Putting this into orbit and turning the reactor on to 100% will result in ~30 kW per radiator worth of heat backflow into the reactor when the radiators are up to ~1060 K where they stabilize. As the ship slowly heats up, this drops down to ~25, where everything stabilizes: the radiators draw 1350 kW, 150 kW of which leaks back and 1200 kW is radiated away, while the reactor produces 1200 kW.

Now take the exact same vessel, and additionally put two pairs of ab-1 heat insulators on the ends of the reactor (double insulated for the win, I figured). And what happens? The backflow from each radiator is barely 3 kW - just one tenth of what it was in the other configuration! Despite the same temperature differential between the radiators and the reactor. Why the heck does it matter what parts are attached to the reactor? It should only be calculated between the radiators and the reactor!

This is messed up, and it's probably a stock issue.

Edited May 13, 2015 by Streetwind

[ExavierMacbeth]

After spending a long time at 100% reactor and engine load, with my radiators nice and heated up, I reverted to the VAB. Made a change (removed the insulators), and launched again. Upon arriving on the launchpad, all six radiators immediately exploded "due to overheating", and the remaining parts of my vessel had large amounts of heat in them.

Reverting to VAB again and launching again --> no problem at all.

I have since not been able to reproduce this at all. Anyone ever seen that kind of thing?

Probobly the side effect of a stock bug. I've reverted rockets (and planes) back to launch/VAB where i was doing burnup mach speeds and had them spawn on the pad still hanging onto the mach speed/heat values (and burn effects) for a few seconds after physics stabilized. Depending on how hot things where before I hit revert this generally caused something to explode lol. Pretty hit and miss when it happens but maybe thats what you saw

[Nertea]

Did some testing of NFEX_4_10 with various configurations of LV-N's and the monster LV-NB (from KSPX) last night. Seems to be a reasonable balance, the radiators are heavy enough to give a noticeable performance hit (accounted for easily enough by either attention to your design or MOAR BOOSTERS!!), but perform well enough that you don't need to spam them in mass quanta to keep temperatures within a decent range for any normal burn length.

That sounds pretty good, actually. Yay!

Okay, testing comments time!

What about the heat exchanger part, the one that conducts really well? It's still a 2.5m placeholder.

Placeholder will be removed, it will take me at least another week to get enough time to make several heat exchangers. So, not for first new version.

Radiators should display their heat transfer capabilities in the VAB, instead of (or in addition to) the estimated total cooling capacity. I'm not even sure that figure is necessary anymore.

Ah yeah I should change it back.

On/off button for radiators, like the heatpipe has one?

I figured that toggle/retract was good enough, but I can do that.

Thermal mass of parts intentionally skewed? 880 on KP-XL PIT (1.1 t) vs. 98 on mx-4 reactor (2.3 t) seems a bit odd.

Thermal mass of reactors is cut down intentionally to make heatup times faster.

After spending a long time at 100% reactor and engine load, with my radiators nice and heated up, I reverted to the VAB. Made a change (removed the insulators), and launched again. Upon arriving on the launchpad, all six radiators immediately exploded "due to overheating", and the remaining parts of my vessel had large amounts of heat in them.

Reverting to VAB again and launching again --> no problem at all.

I have since not been able to reproduce this at all. Anyone ever seen that kind of thing?

How the heck does KSP calculate conductive flux?! o___o

Consider this ship: small nose cone, mk1 command pod, erg-20 argon tank, mx-4 reactor / 6x GR-4 radiator, KP-XL PIT

Putting this into orbit and turning the reactor on to 100% will result in ~30 kW per radiator worth of heat backflow into the reactor when the radiators are up to ~1060 K where they stabilize. As the ship slowly heats up, this drops down to ~25, where everything stabilizes: the radiators draw 1350 kW, 150 kW of which leaks back and 1200 kW is radiated away, while the reactor produces 1200 kW.

Now take the exact same vessel, and additionally put two pairs of ab-1 heat insulators on the ends of the reactor (double insulated for the win, I figured). And what happens? The backflow from each radiator is barely 3 kW - just one tenth of what it was in the other configuration! Despite the same temperature differential between the radiators and the reactor. Why the heck does it matter what parts are attached to the reactor? It should only be calculated between the radiators and the reactor!

This is messed up, and it's probably a stock issue.

These both seem like things I can't really work on

[Starbuckminsterfullerton]

Just a quick note because maybe you already noticed, but 1.25m Argon tank No. 3 is missing a description. The new NFP tank set looks great by the way, even though I already said so about the dev renders.

[DerekL1963]

Actually, I like seeing the total cooling capacity - it gives a nice easy number to compare radiators and make a quasi-intelligent selection.

[Fraz86]

I love the heat pipes, but unfortunately they are very exploitable. See the picture below:

The reactor temperature of this vessel stabilized at 306K.

Basically, a single heat pipe provides the same "active cooling" capability as a GR-1 radiator, but at 1/10 the mass. Of course the heat pipe can't actually dissipate the heat itself, but combine a heat pipe with a do-it-yourself radiator (e.g., a small shielded wing), and it will be just as effective as an actual radiator at a fraction the mass & cost. Here are the numbers comparing the GR-1 vs the DIY radiator pictured above.

[table=width: 600]

[tr]

[td][/td]

[td]Effective Heat Rejection[/td]

[td]Total Mass[/td]

[td]Total Cost[/td]

[/tr]

[tr]

[td]GR-1 Conformal Heat Radiator[/td]

[td]1250[/td]

[td]0.5[/td]

[td]10000[/td]

[/tr]

[tr]

[td]DIY Radiator (Heat Pipe + Cubic Octagonal Strut x5 + Structural Wing Type D)[/td]

[td]1250[/td]

[td]0.08[/td]

[td]380[/td]

[/tr]

[/table]

As you can see, it's completely unbalanced. Unfortunately, I'm not sure what solution to propose, though I think it's fair to say that heat pipes need some kind of additional limitations/disadvantages. Perhaps heat pipes should merely create high conductivity between the two attached parts, with no "active cooling" capability?

Edited May 14, 2015 by Fraz86

[Nertea]

Just a quick note because maybe you already noticed, but 1.25m Argon tank No. 3 is missing a description. The new NFP tank set looks great by the way, even though I already said so about the dev renders.

Nah I hadn't caught that. Thanks!

Actually, I like seeing the total cooling capacity - it gives a nice easy number to compare radiators and make a quasi-intelligent selection.

It's still there, it's just not estimated anymore.

I love the heat pipes, but unfortunately they are very exploitable. See the picture below:

http://i.imgur.com/grgWPzi.jpg

The reactor temperature of this vessel stabilized at 306K.

Basically, a single heat pipe provides the same "active cooling" capability as a GR-1 radiator, but at 1/10 the mass. Of course the heat pipe can't actually dissipate the heat itself, but combine a heat pipe with a do-it-yourself radiator (e.g., a small shielded wing), and it will be just as effective as an actual radiator at a fraction the mass & cost. Here are the numbers comparing the GR-1 vs the DIY radiator pictured above.

[table=width: 600]

[tr]

[td][/td]

[td]Effective Heat Rejection[/td]

[td]Total Mass[/td]

[td]Total Cost[/td]

[/tr]

[tr]

[td]GR-1 Conformal Heat Radiator[/td]

[td]1250[/td]

[td]0.5[/td]

[td]10000[/td]

[/tr]

[tr]

[td]DIY Radiator (Heat Pipe + Cubic Octagonal Strut x5 + Structural Wing Type D)[/td]

[td]1250[/td]

[td]0.08[/td]

[td]380[/td]

[/tr]

[/table]

As you can see, it's completely unbalanced. Unfortunately, I'm not sure what solution to propose, though I think it's fair to say that heat pipes need some kind of additional limitations/disadvantages. Perhaps heat pipes should merely create high conductivity between the two attached parts, with no "active cooling" capability?

Problematic. I can't just make it conduct between things, it would probably be quite involved to hack into the heat graph like that. What I can do is increase the price considerably (because I think I didn't change it from the fuel pipe), increase the mass a touch too. Another solution could be to give pumping heat a power cost, so that would make complex heat pipe setups more costly.

Other than that I'm not sure what to do there!

[Fraz86]

Problematic. I can't just make it conduct between things, it would probably be quite involved to hack into the heat graph like that. What I can do is increase the price considerably (because I think I didn't change it from the fuel pipe), increase the mass a touch too. Another solution could be to give pumping heat a power cost, so that would make complex heat pipe setups more costly.

Other than that I'm not sure what to do there!

Would it be possible to make heat pipes incapable of transferring heat when the receiving part is hotter than the source part? If so, I think that would work well. It would provide an excellent incentive to attach actual radiators to the receiving part to keep its temperature low, so that heat can continue to be removed from the source part.

[Nertea]

Yeah that's possible and seems like a good idea. I'll try that and we can see how it works.

[ExavierMacbeth]

There is a problem with your test. Try it in orbit

Kerbins atmosphere is pretty good with dissipating heat. One of the problems ppl where having (still are to a lesser extent) is that they test their Nervas on the ground and don't realize that once its in orbit the heat buildup is much much faster.

[Fraz86]

There is a problem with your test. Try it in orbit

Kerbins atmosphere is pretty good with dissipating heat. One of the problems ppl where having (still are to a lesser extent) is that they test their Nervas on the ground and don't realize that once its in orbit the heat buildup is much much faster.

Here you go:

Reactor temperature stabilized at 280K, even lower than it was in the atmosphere. The structural wings did get warmer (1556K in space vs 1427K in atmosphere), but still well below their 2000K maxTemp.

[helaeon]

The real problem is the wing's thermal tolerance is too high... 2000K radiators are a carbon metamaterial magic (that is possible and does exist) and would be used on a reactor like the SAFE400. You'd heat those radiators up so far that they'd emit IR energy like crazy and be very efficient even at a small size. And yes, you'd use heat pipes to get to them, then the coolant would go back into the radiator to heat up the coolant again, and repeat. This is how electricity is generated, it's an ideal engine cycle (Brayton Turbine in the case of the SAFE400).

Interesting thing is when you heat a radiator up that far they don't need to be that big either, the hotter the radiator's temperature, the more kWt it loses to space. (the increase is to the 4th power)

The reason the ISS needs such big radiators is they aren't very hot.

In this case, even on the ground, most of your heat loss is through radiation not convection or conduction. Actually being on the ground means that you're radiating at a grey body, so it's not as efficient. In this case facing out into black space, yep... this is working as it should from what I can tell. Those two radiators facing the sun shouldn't be radiating as much, but those two perpendicular to it would be very effective.

On the radiators for the NTRs: I haven't been watching this thread super close, but the NTRs should be losing all of their bulidup heat through the propellant while running. It's when they're not running that something must be done to cool the reactor (which could be done by turning down the fission reaction, which means you would have to spin it up again before you could use the engine again). Probably using it as a generator to turn those watts of thermal energy to electrical energy, then you'd radiate your heat energy off into space. Basically using it like a giant RTG, large radiators should not be needed. I've yet to fiddle with the stock NTR... but from prior use and other engines it sounds like it's backwards. It generates a lot of heat while running and is cool when it's idle. The heat is what makes it work and have its high ISP!

Edited May 14, 2015 by helaeon