[WIP] Nert's Dev Thread - Current: such nuke, wow

[Sage]

Having consequences is a good idea, yes - you just need to be careful about the what and how. Your example with the boiloff causing vapor plumes is pretty good - not realistic, but quite suitable for a game (especially a lighthearted one). I was arguing against blind realism for realism's sake, not against implementing real concepts in a believable way

The aero thing can probably be argued, I found that especially planes got more intuitive and controllable. I also think that "my plane/rocket must be aerodynamic" is much more on the forefront of player's minds than "my plane/rocket needs to reject excess heat". But perception plays a big role in these things, and I suspect this perception would differ based on previous exposure to FAR...

Sorry I misunderstood your post then I'm a great fan of borrowing from RL what we need without making it just for its sake too. I guess it comes down to "believability" in the end.

Also I was referring to FAR, in fact I'm already playing with nuFAR installed. In stock I can't get my hands on the stability derivatives, that, while is it arguable that presenting them as hard numbers (actually the green/red is wonderful) and with mathematic description only could be a bit unfriendly, they are a must to build a plane, and once you got in a mindset that certain ones affect certain maneuvers they are pretty straightforward and fun to optimize.

Another thing that comes to mind about having something modeled against RL physics but with concession to it are radiators and engines that glow with their temperatures. It looks badass, and the first lifter engines overheat put the attention of the player on the fact that heat exists in the game, without hard consequences since the stage is jettisoned early. What is missing now is the temp readouts on parts right-click menu, to further cement this idea while in space too and to give a feedback before everything is in the red zone. Presenting the first radiators and insulators with the nuke engine or shortly before while giving hints in their description on how heat flows could be a great way to ease the player into thinking about heat management.

[FreeThinker]

How is heat removed for new NFT reactors?

For the KSPI VISTA Fusion Propulsion system, I create a combination of exisitng KSPI heat management and KSP Heating. Because the Vista Fusion engine produces the same amount of fusion, no matter the throttle, I set the heat Engines heatProduction at amount of recieved radiator (10000 MW) and divide by trottle to make the amount of heat generated constant. I Would then set the dissapation factor at 4 x PartMass x RadiatorsPPerformance. The result is a initially very fast heating fusion engine which will explode unless you have enough radiators or stop the fusion process.

Edited May 6, 2015 by FreeThinker

[Psycho_zs]

IMHO, VAB info for radiators should also show estimated heat flow at nominal temp. But since reactors have different nominal temp, then maybe show three data points: 700K, 900K, Max temp. or something like that.

[Nertea]

I don't think cryogenic boiloff is unintuitive, actually. I think it makes for poor gameplay in vanilla KSP. There's already a really huge disadvantage to LH2 in that it's very space-inefficient. Boiloff is a totally, completely messy problem, I'll explain at length if anyone wants, but in summary, RealFuels! I never intended to provide a realistic simulation. I intended to provide a framework that significantly sacrifices realism, because realism doesn't work without other components being realistic. I'm totally open to someone doing a NFT-RO config, but I won't be doing it. I already get enough complaints about "breaking" the LV-N and the stock ion.

@riocrokite: Reactors now can't be repaired when below 10% core integrity, and continue to take core damage when offline. Core damage increases fuel use and heat generation rapidly too.

[riocrokite]

@riocrokite: Reactors now can't be repaired when below 10% core integrity, and continue to take core damage when offline. Core damage increases fuel use and heat generation rapidly too.

Awesome \o/ erm... I think we have intergalactic meltdown, Jeb, do you copy?

[Fraz86]

IMHO, VAB info for radiators should also show estimated heat flow at nominal temp. But since reactors have different nominal temp, then maybe show three data points: 700K, 900K, Max temp. or something like that.

Expecting users to sift through different heat dissipation rates for different temperatures in different reactors is overly complex, I'm afraid. I think the reactors should be tuned to all share the same nominal temp. That way, all radiators can specify "Heat dissipation provided at nominal reactor temp," which can be intuitively matched against a "Heat dissipation required at nominal reactor temp" for the reactors.

That said, I'm still not convinced that the nominal temperature concept is a good gameplay mechanic in the first place. On the one hand, it does offer an incentive to keep one's spacecraft cooled to a reasonable temperature. This is good, in principle. On the other hand, it means the nuclear reactor is now the most heat-sensitive part of the spacecraft, which is completely counter-intuitive, unrealistic, and not believable.

Intuitively, I would assume that a reactor would be quite hot, and that I should insulate things like crew capsules and fuel tanks to protect them from the heat of the reactor. Instead, the opposite will be true if this mechanic is implemented. Placing insulators to protect a crew capsule provides no benefit (because the Kerbals don't mind being roasted alive), and would in fact be disadvantageous because the insulator would prevent the reactor from utilizing those poor Kerbals as the convenient radiators that they are.

Basically, if a gameplay mechanic is implemented to encourage keeping a reactor cooled to a reasonable temperature, we need similar mechanics for other parts that should also be heat-sensitive. Otherwise, you're incentivizing players to facilitate the propagation of a reactor's heat throughout the entirety of the spacecraft, which is contrary to intuition. However, introducing consequences for over-heating other parts would be a sizable task (possibly out-of-scope for this mod), and may ultimately result in a gameplay experience that is frustrating and confusing (for reason's outlined by Streetwind). Therefore, perhaps it would be best for NFE to largely extricate itself from this dilemma by making it impossible to effectively use one's spacecraft as a giant radiator, which could be accomplished through Streetwind's proposal (reactor conductivity near zero, thus requiring the "active cooling").

Edited May 6, 2015 by Fraz86

[riocrokite]

Expecting users to sift through different heat dissipation rates for different temperatures in different reactors is overly complex, I'm afraid. I think the reactors should be tuned to all share the same nominal temp. That way, all radiators can specify "Heat dissipation provided at nominal reactor temp," which can be intuitively matched against a "Heat dissipation required at nominal reactor temp" for the reactors.

That said, I'm still not convinced that the nominal temperature concept is a good gameplay mechanic in the first place. On the one hand, it does offer an incentive to keep one's spacecraft cooled to a reasonable temperature. This is good, in principle. On the other hand, it means the nuclear reactor is now the most heat-sensitive part of the spacecraft, which is completely counter-intuitive, unrealistic, and not believable.

Intuitively, I would assume that a reactor would be quite hot, and that I should insulate things like crew capsules and fuel tanks to protect them from the heat of the reactor. Instead, the opposite will be true if this mechanic is implemented. Placing insulators to protect a crew capsule provides no benefit (because the Kerbals don't mind being roasted alive), and would in fact be disadvantageous because the insulator would prevent the reactor from utilizing those poor Kerbals as the convenient radiators that they are.

Basically, if a gameplay mechanic is implemented to encourage keeping a reactor cooled to a reasonable temperature, we need similar mechanics for other parts that should also be heat-sensitive. Otherwise, you're incentivizing players to facilitate the propagation of a reactor's heat throughout the entirety of the spacecraft, which is contrary to intuition. However, introducing consequences for over-heating other parts would be a sizable task (possibly out-of-scope for this mod), and may ultimately result in a gameplay experience that is frustrating and confusing (for reason's outlined by Streetwind). Therefore, perhaps it would be best for NFE to largely extricate itself from this dilemma by making it impossible to effectively use one's spacecraft as a giant radiator, which could be accomplished through Streetwind's proposal (reactor conductivity near zero, thus requiring the "active cooling").

yah, it all boils down to the problem of wrong configuration for stock tanks and other parts that aren't and can't be heat sinks nor sustain high temperatures. So I expect sooner or later that Squad will revamp that with introduction of proper radiators. So for now building complicated system to work with stock will be always more or less flaved. the solution with radiators working exclusively with reactor might be good now but it's not future-proof concept that can be easily tweaked when things change in stock. (also glowing heat pipes \o/ are awesome).

[Fraz86]

yah, it all boils down to the problem of wrong configuration for stock tanks and other parts that aren't and can't be heat sinks nor sustain high temperatures. So I expect sooner or later that Squad will revamp that with introduction of proper radiators. So for now building complicated system to work with stock will be always more or less flaved. the solution with radiators working exclusively with reactor might be good now but it's not future-proof concept that can be easily tweaked when things change in stock. (also glowing heat pipes \o/ are awesome).

I wouldn't be so sure that Squad will ever significantly revamp heat management. They created the current heat system primarily to provide a reasonable model for re-entry heating. It sufficiently accomplishes that purpose (or, rather, it will once they fix the problems they created with changes to the aero model in 1.01/1.02).

Beyond this limited scope, it would be very difficult to implement comprehensive heat management mechanics that make for fun gameplay (see Streetwind's posts for some of the reasons why). I strongly doubt that Squad will ever dramatically revise the current heat mechanics.

[Streetwind]

Intuitively, I would assume that a reactor would be quite hot, and that I should insulate things like crew capsules and fuel tanks to protect them from the heat of the reactor. (...)

Not necessarily... reactor cores are hot, reactors themselves not so much

These things tend to be massively shielded, for two reasons. First, radiation. Second, thermal efficiency. Every bit of heat loss from the reactor vessel itself is heat you cannot use to generate the temperature differential required for power production. Thus, the ideal reactor is hot down in the core, but completely benign and cool on the outer skin, and exchanges absolutely no heat whatsoever with its surroundings. A lot of money and engineering is thrown at making things behave this way.

Heat is then routed (in the form of coolant fluid or gas) from the core into a heat engine that transforms the energy into a different format (usually kinetic, via a brayton cycle turbine). In order for the heat engine to work, there must be a lower temperature "sink" that heat can flow towards. Those are the radiators. The larger and better quality the radiators are, and the higher the reactor's core temperature, the larger the temperature differential between the core and the radiators will be; and the larger the differential, the better the heat engine will run. Finally, the coolant is routed from the radiators back into the core to be re-heated.

That's why I suggested in my earlier post to make the reactor a strongly thermally insulated part. Or alternatively, decouple the heat of the reactor core from the heat of the vessel itself, using a dedicated standalone heat simulation like it was in past versions. That would fairly well present the difference between the thermally insulated inner core (handled by the dedicated plugin) and the reactor vessel as a part of the spacecraft structure as a whole (handled by the stock system).

However I get the impression Nertea likes the heat system, and has future plans... And personally, as long as it plays nicely in the end, I won't be too concerned of the exact details.

[KwirkyJ]

Not necessarily... reactor cores are hot, reactors themselves not so much

These things tend to be massively shielded, for two reasons. First, radiation. Second, thermal efficiency. Every bit of heat loss from the reactor vessel itself is heat you cannot use to generate the temperature differential required for power production. Thus, the ideal reactor is hot down in the core, but completely benign and cool on the outer skin, and exchanges absolutely no heat whatsoever with its surroundings. A lot of money and engineering is thrown at making things behave this way.

Heat is then routed (in the form of coolant fluid or gas) from the core into a heat engine that transforms the energy into a different format (usually kinetic, via a brayton cycle turbine). In order for the heat engine to work, there must be a lower temperature "sink" that heat can flow towards. Those are the radiators. The larger and better quality the radiators are, and the higher the reactor's core temperature, the larger the temperature differential between the core and the radiators will be; and the larger the differential, the better the heat engine will run. Finally, the coolant is routed from the radiators back into the core to be re-heated.

That's why I suggested in my earlier post to make the reactor a strongly thermally insulated part. Or alternatively, decouple the heat of the reactor core from the heat of the vessel itself, using a dedicated standalone heat simulation like it was in past versions. That would fairly well present the difference between the thermally insulated inner core (handled by the dedicated plugin) and the reactor vessel as a part of the spacecraft structure as a whole (handled by the stock system).

However I get the impression Nertea likes the heat system, and has future plans... And personally, as long as it plays nicely in the end, I won't be too concerned of the exact details.

It is actually this very thinking -- that the heat-generating reactor should be separated from the electricity-generation component -- that I created a Seebeck Generator mod. It may go against the way Nertea wishes to implement things, but this mechanic does exist.

[Nertea]

New version, X.4.8. I think we are getting there. This feels decent.

• Reactors now can't be repaired when below 10% core integrity
  
• Core damage continues if reactor is off
  
• Core damage increases reactor heat production (+200% at 0% core) and fuel burn rate (chances are all fuel will be DU when at 0%)
  
• New implementation of radiator heat system based on suggestions from Streetwind, toggle it on or off in the VAB
  
• When on, radiators will become low conductivity high emissivity objects that will take heat out of the attached part and add it to themselves to be radiated
  
• Decreased reactor conductivity slightly
  

[billkerbinsky]

Heat is then routed (in the form of coolant fluid or gas) from the core into a heat engine that transforms the energy into a different format (usually kinetic, via a brayton cycle turbine). In order for the heat engine to work, there must be a lower temperature "sink" that heat can flow towards. Those are the radiators. The larger and better quality the radiators are, and the higher the reactor's core temperature, the larger the temperature differential between the core and the radiators will be; and the larger the differential, the better the heat engine will run. Finally, the coolant is routed from the radiators back into the core to be re-heated.

So KSP gives you an intuitive understanding of orbital mechanics; while NFE gives you an intuitive understanding of thermodynamics and reactor physics? :-)

seriously, I like this model..

[Fraz86]

New version, X.4.8.

The link doesn't seem to be working for me.

[Psycho_zs]

File is deleted

[quote name='Nertea;1913378

• New implementation of radiator heat system based on suggestions from Streetwind' date=' toggle it on or off in the VAB
  [*'] When on, radiators will become low conductivity high emissivity objects that will take heat out of the attached part and add it to themselves to be radiated
  

[Captain Sierra]

-snip of awesome stuff-

So those radiators working off the stock heat mechanics or are you keeping it an isolated system, only converting to stock heat when your system reaches capacity?

[Nertea]

Oops, here is corrected link. You can toggle implementations for testing only. Will choose one eventually.

https://www.dropbox.com/s/ilr7qr8z4agmbi5/NearFutureElectricalX_4_8.zip?dl=0

[Psycho_zs]

Hm, I see heat created by radiators, some of it conducted back to the reactor and radiated away by reactor!

- - - Updated - - -

And they suck heat from parts that already cooler.

[Fraz86]

Not necessarily... reactor cores are hot, reactors themselves not so much

Fair enough, and thank you for the thorough explanation, but doesn't the above statement assume that the reactor an appropriate array of radiators installed? Without those radiators (or if the player is choosing to use his/her entire spacecraft as a radiator), then I would imagine the reactor would get a bit warm, no? This is really the scenario that I was speaking to. It does seem intuitive that - with proper heat dissipation through dedicated radiators - I wouldn't need to I should insulate crew capsules and fuel tanks from the heat of the reactor. I only meant that this insulation would be intuitively necessary if one was using the structure of the vessel to radiate the reactor's heat, which is basically how it currently functions. Thanks again for the detailed information; it really is interesting to learn how these things work in the real world!

Edit:

This is an interesting consequence of the "Streetwind" radiators (compare the radiator temperature vs reactor temperature):

Edited May 7, 2015 by Fraz86

[Fraz86]

After toying with them for a while, I do like the ease of use of the Streetwind radiators, though their ability to cool things to near absolute zero feels a bit silly. Perhaps ambient temperature would be a reasonable lower limit? Or make it such that the "active cooling" function of radiators can only remove the positive internal temperature flux of the part they're attached to, but cannot actually induce a negative flux.

With either type of radiator, I noticed some odd behaviors with high time warps (I believe it was x1000 or greater), such as dramatic instantaneous temperature changes (e.g., 750K -> 300K) even though nothing else changed.

Also, now that we're using nominal temps, is it necessary to keep reactor and radiator maxTemps so low? It feels a bit counter-intuitive. Especially radiators; I would have assumed they would have higher temperature tolerances than most parts. As it is now, reactors and radiators are quite likely to explode during re-entry.

Lastly, it would be nice if the right click display for reactors provided information regarding nominal and critical temps. A "Current Heat Output" field would also be nice, corresponding to the radiator's "Current Heat Input."

Edited May 7, 2015 by Fraz86

[Streetwind]

Hm, I see heat created by radiators, some of it conducted back to the reactor and radiated away by reactor!

That's perfectly logical. The radiators are hot, after all, and the reactor outer structure on which they are mounted is not. Of course it would leak a little, if there's no insulation. Still, with the radiators being so good at radiating, the vast majority of the heat should get shunted into space... in the heat-sucking configuration, they should not have as high a conductivity as they do when they must rely on passive conductivity to work.

Fair enough, and thank you for the thorough explanation, but doesn't the above statement assume that the reactor an appropriate array of radiators installed? Without those radiators (or if the player is choosing to use his/her entire spacecraft as a radiator), then I would imagine the reactor would get a bit warm, no? This is really the scenario that I was speaking to. It does seem intuitive that - with proper heat dissipation through dedicated radiators - I wouldn't need to I should insulate crew capsules and fuel tanks from the heat of the reactor. I only meant that this insulation would be intuitively necessary if one was using the structure of the vessel to radiate the reactor's heat, which is basically how it currently functions. Thanks again for the detailed information; it really is interesting to learn how these things work in the real world!

Well, technically a RL reactor without any heat sink attached would eventually get hot, too, yes. But not in the way you think.

The insulation is so massive that by the time the outside shell gets significantly heated, the reactor on the inside has long since liquified from crazy overheating. There's no reactor left - no fuel rods, no control rods, no coolant ducts, no structural elements and so on. Just a shapeless mass of runaway-radioactive liquid metal (called "corium") that then burns a hole through the bottom of the pressure vessel and escapes. This is why reactor accidents are called "meltdowns" - you can take the word 100% literal. It simply melts down. For fun and awe, try googling "elephant's foot". That's what they dubbed the molten remains of the Chernobyl reactor core. They managed to take a photo of it with a remote-controlled robot hiding behind a corridor corner and using a mirror to get a view on it... anything trying to get a direct view, even the robot, would not have survived. It is still ruled unapproachable to this day. Scaaary stuff!

(Bonus: exploding reactors. This happens if an overheating core, or liquid corium, comes into direct contact with water coolant. For starters, there's a powerful steam explosion; but the intense energy produced by an out of control reactor core can also be enough to actually split water into H2 and O2. Which then recombines in an oxyhydrogen detonation that's even more devastating and will generally wreck the whole building. However, contrary to popular belief, reactors do not, and in fact cannot, achieve a pure nuclear explosion event like a fission bomb.)

Now, a reactor in space... since there's no gravity, the corium would remain in place inside the pressure vessel and eventually heat up the whole reactor to the point of structural failure. In that scenario it would very much cook the rest of the spacecraft along with it. Still, at that point your reactor core is long gone.

Not sure what your screenshot means. The reactor is offline?

I'd love to test together with you guys, but Nertea has this habit of posting his test builds shortly after I need to sleep. *fistshakes*

Which means that I generally don't get to play with them until ~18 hours after the rest of you

- - - Updated - - -

(...) Or make it such that the "active cooling" function of radiators can only remove the positive internal temperature flux of the part they're attached to, but cannot actually induce a negative flux.

That was actually the intention I had behind the suggestion, yes.

With either type of radiator, I noticed some odd behaviors with high time warps (I believe it was x1000 or greater), such as dramatic instantaneous temperature changes (e.g., 750K -> 300K) even though nothing else changed.

Stock behavior, happens with stock heat sources too. Timewarp x1000 and greater simply skips calculating things like heat entirely.

[Honeybadga]

Do you think we'll be able to upgrade our career saves from X 4.8 to stable without many bumps? Are the parts assigned to their proper tech nodes yet? I don't mind if the heat management part is still subject to change, just asking because I wanna start using the nice batteries and maybe capacitors?

[Psycho_zs]

OK, to summarize everything...

Reactor is presented to stock heat mechanics as an insulated shell, it has a heated core 'inside' governed by own mechanics. Radiators draw heat from core. If there aren't enough radiator capacity, heat overflows to reactor shell.

If that is the case, then instead of radiators that have low conductivity and magically suck heat like refrigerators, let them be normal efficient radiators with 0.95 conductivity and 0.95 emissivity with the only trick - when attached to the reactor they would act as if they are attached directly to the core. Reactor's own low conductivity would prevent too much heat transfer from radiators to it and the rest of the ship. Reactor shell could have normal emissivity, no difficulties here. And radiators would still be usable as an organic part of stock heat mechanics alongside heat insulators and conductors.

[Fraz86]

Well, technically a RL reactor without any heat sink attached would eventually get hot, too, yes. But not in the way you think.

The insulation is so massive that by the time the outside shell gets significantly heated, the reactor on the inside has long since liquified from crazy overheating. There's no reactor left - no fuel rods, no control rods, no coolant ducts, no structural elements and so on. Just a shapeless mass of runaway-radioactive liquid metal (called "corium") that then burns a hole through the bottom of the pressure vessel and escapes. This is why reactor accidents are called "meltdowns" - you can take the word 100% literal. It simply melts down. For fun and awe, try googling "elephant's foot". That's what they dubbed the molten remains of the Chernobyl reactor core. They managed to take a photo of it with a remote-controlled robot hiding behind a corridor corner and using a mirror to get a view on it... anything trying to get a direct view, even the robot, would not have survived. It is still ruled unapproachable to this day. Scaaary stuff!

(Bonus: exploding reactors. This happens if an overheating core, or liquid corium, comes into direct contact with water coolant. For starters, there's a powerful steam explosion; but the intense energy produced by an out of control reactor core can also be enough to actually split water into H2 and O2. Which then recombines in an oxyhydrogen detonation that's even more devastating and will generally wreck the whole building. However, contrary to popular belief, reactors do not, and in fact cannot, achieve a pure nuclear explosion event like a fission bomb.)

Now, a reactor in space... since there's no gravity, the corium would remain in place inside the pressure vessel and eventually heat up the whole reactor to the point of structural failure. In that scenario it would very much cook the rest of the spacecraft along with it. Still, at that point your reactor core is long gone.

Very interesting! What if the heat sink piping of the reactor was intentionally connected to the structure of the spacecraft? That is, could the reactor be engineered to use the spacecraft itself to radiate some of its heat? In the context of space flight, in which you don't want to bring a single kilogram more than necessary of dedicated radiators, is such a thing at all plausible? I'm asking mainly because I'm curious if the current behavior - in which a non-trivial portion of reactor heat is radiated through the spacecraft - can be rationalized.

Not sure what your screenshot means. The reactor is offline?

Yes, it's an offline MX-1 reactor sitting on the launchpad with four "Streetwind-mode" GR-1 radiators attached and fully deployed. The screenshot illustrates that this setup reaches a steady state with the radiators hovering around 422K and the reactor stable at 4K. These findings seemed a bit extreme .

[Streetwind]

Ah yes, I see what you mean. That's basically what Fraz86 said, the radiators steal all heat they can find. My original suggestion was that they only steal positive internal flux, but maybe that's not easily possible to implement...

Re: spacecraft as radiators. IRL, that would be a big no-no. You already have issues with spacecraft overheating due to solar thermal flux; the Apollo capsule and service module for example were polished to a mirror finish to minimize that effect, but they still needed a bit of dedicated radiator surface. The ISS has entire banks of radiators just to cool itself (especially the solar panels, which would melt otherwise). Compared to RL spacecraft, KSP spacecraft are really really good at radiating. Also, the differences between facing the sun and being in the shadow are extreme. You can have the sun-facing part of your spacecraft heat up to over a hundred degrees while the shadowed side goes down to -250 or more. This causes major stresses in the material. The aforementioned Apollo module was put into a slow rotation with respect to the sun in order to evenly distribute solar heating and prevent any area from getting too hot or too cold. They called it the "barbecue roll" (well, unofficially, anyway).

Also, internal temperature tolerances. Electronics probably don't do well under more than a a few hundred degrees at the very most; humans don't do well even under a hundred degrees. IRL spacecraft and rovers invest a lot of effort into temperature control. Active cooling systems and climate control; heaters, as well. China lost its Yutu rover on the Moon because lunar dust got into mechanical actuators and made it unable to fold up for the long lunar night - thus it was not able to effectively keep itself heated on battery power, and it woke up beyond repair.

KSP spacecraft make great radiators not only because they radiate really well, but also because you can produce an insane temperature differential between the ship and cold space. 1200 degrees crew capsule and liquid hydrogen tank? No problem! IRL the crew would be dead and the tank would have exploded... both would have happened long before reaching 1200 degrees, in fact. And if you can only do a small temperature differential, it's essentially worthless because there won't be much radiating happening.

[Streetwind]

NFP news:

I just passed Nertea a first draft for new engine stats. Tiers 3 and 4 got nerfed across the board, and some numbers changed around on pretty much all engines. You will no longer be able obtain TWRs greater than 2.0 Kerbin-relative with any electric engine. This was done in order to keep the nerfed LV-N relevant in at least a select few scenarios.

The engines also have a heat output now, and it's set on the high end for what I consider reasonable. Whenever Nertea gets around to pushing a new test build, please test especially with an eye towards vessel heating during long burns. The good news is - though I call it high, it should still be a far cry from the LV-N