Developer Insights #21 - Rockets' Red Glare

[Periple]

I hope there will be mods that add this kind of realism to KSP2 eventually! FAR-like aerodynamics, n-body physics, realistic life support, and more physically accurate thermals would change the feel of the game a quite a lot and would be an interesting new challenge. I think it could even ben done so that only the currently controlled craft gets the full simulation with everything else falling back on the cruder standard approximations!

[RocketRockington]

12 hours ago, Periple said:

The OP describes the system and also why they made this simplification: there are very few gameplay situations where the more accurate simulation would make a noticeable difference, as in most situations the fluxes from the environment are much higher than conductivity between parts, while the simplification is much less expensive and allows them to simulate thermals on craft that aren't in the physics bubble as well as craft with very large part counts. It also makes it easier to design/balance parts as you'll have one fewer parameter to tune since you won't need to worry about how good thermal conductors or insulators they are.

 

Unfortunately for the OP, the parts that are most interesting are when internal conduction isn't fast enough to keep up.  EG: Columbia disaster.  Didn't happen because the whole shuttle got too hot - it's because a piece of its skin lost its heat shield and that part got too hot.

Throwing away skin vs internal temperature modelling means that every part acts like a giant heat sink, if thermal masses are set at all realistically - which they probably won't be, because it's only 'reality-inspired'.

Edited July 24, 2023 by RocketRockington

[Mushylog]

This was a long but great reading! Very informative. It's very interesting to see how deep the mechanisms of the game are, or can be, or will be! It all makes sense and I'm very excited to see what you come up with in the future. KSP2 is a great game, I am most excited to see the new planets, but any of the roadmap goals hype me up too. Re-entry heating is going to spice it up real nice!!

ps: a few typos in this post confused me a little, but I got the gist of it! And the examples were very practical and useful. Great drawings too haha (the flame/candle with the inverted red/yellow!! )

[000PainKiller000]

Will there be seasons on planets with axial tilt? That would make a lot of fun when planning a colony to consider. 

Edited July 24, 2023 by 000PainKiller000

[Jokari]

Thanks for all the information. It's interesting and even enlightening to read about internal structure of the game.

But I can't help but notice that everything said in this post seems "theoretic". You are laying down your vision about heat management and make no promise about a release timeline. Fair, fine, and prudent. Love it. But it means that you are just walking from the drawing board to start coding all that stuff?

Don't you have a little something to show in-game about heat management please?

[Bombaatu]

@Nertea - "Consider a Spherical Cow". Nice reference to "Astrophysics for People in a Hurry" 

[JPR]

The heat model in KSP2 seems to be worse than KSP1, as the developers have chosen to move away from KSP1's detailed simulation approach in favor of a deterministic model.  KSP1 with RSS (Real Solar System), RP1 (Realistic Progression 1) and RO (Realism Overhaul) installed is a much better game than KSP2. The foundation for KSP2 should have been built upon the KSP1 experiences with RSS +RO + Principia. Flying realistic rockets in the real world with real engines. They could have also kept the parts count down with procedural tanks.  Difficulty could be scaled N-Body Physics (Higher Difficulty) vs 2-Body Physics (Lower Difficulty) the same for complexity of live support.

[Vanamonde]

A number of posts not about the game's heat system have been moved to The Grand Discussion thread. 

[FleshJeb]

On 7/21/2023 at 9:45 AM, Intercept Games said:

We don’t have a lot of user stories that benefit from simulating conduction between parts,

100% disagree. Learning how to manage heat flows through a craft is incredibly interesting, and leads to needing to use both conductive and insulative parts in the right places.

This single-stage, heatshieldless Jool diver is the most personally rewarding project I undertook in KSP 1, and there are no exploits involved:

[mcdjfp]

A bit more aggressive than my fuel saving aerobraking returning from the Mun/Minmus using my passenger shuttle.

 

Edit: Even being less aggressive I still take care to not overheat the wrong parts.

Edited July 24, 2023 by mcdjfp
Further explanation

[The Aziz]

20 minutes ago, FleshJeb said:

100% disagree. Learning how to manage heat flows through a craft is incredibly interesting, and leads to needing to use both conductive and insulative parts in the right places.

This single-stage, heatshieldless Jool diver is the most personally rewarding project I undertook in KSP 1, and there are no exploits involved:

Same energy

[mcwaffles2003]

I love that we will be getting in depth thermal systems and even more so that there is a focus on them running in the background. Admittedly I'm imagining 1 million ways to break this system to test it's limits when it comes out but if something like this can be performant Ill be stunned regardless. 

Personally, though I enjoy the over complication of things like this, I understand it will probably start out really basic or simple. I just hope that over time the mechanics grow to a fair bit of nuance and I wouldn't be sad to see mods take it from there so long as the base mechanics are sound for that kind of modding to take place.

Can't wait to see where this all ends up in a couple years

LET EM COOK!

[shdwlrd]

Thanks Nertea for the in depth explanation of how thermals will work.

[Guest]

10 hours ago, FleshJeb said:

100% disagree. Learning how to manage heat flows through a craft is incredibly interesting, and leads to needing to use both conductive and insulative parts in the right places.

This single-stage, heatshieldless Jool diver is the most personally rewarding project I undertook in KSP 1, and there are no exploits involved:

The fact that you had to dive into Jool's atmosphere to make heat conduction between parts relevant kinda proves the point...

 

On 7/24/2023 at 8:15 AM, RocketRockington said:

Unfortunately for the OP, the parts that are most interesting are when internal conduction isn't fast enough to keep up.  EG: Columbia disaster.  Didn't happen because the whole shuttle got too hot - it's because a piece of its skin lost its heat shield and that part got too hot.

Except there's no such a thing as a spaceplane heat tile in KSP, and generally used method for heat control during reentry, other than just being gentler with the profile, for spaceplanes is to just spin it as fast as possible to roast it evenly on both sides.

Internal conduction between parts never* resulted in interesting gameplay in KSP1.

Simplifying the never used simulation mechanics will allow to reduce the margin for error given that it can be expected from the player to understand how the simpler system works, thus making heat-related failure modes more common and easily achievable, increasing the overall challenge of the game.

 

At some point in simulation complexity you stop adding gameplay challenges and turn it into tedium or into making the player feel like it's just a random system.

 

_{*:ok except for Jool diving.}

[mcwaffles2003]

On 7/21/2023 at 10:14 PM, PDCWolf said:

The writeup explaining the system is excellent, however the nature of the system and some stuff left out are clear problems:

• You're trying to tell me this is more complex, yet all you talk about is how it is more simple. Telling me how the sequel improves over the original is a main selling point, and whilst you tell me there's more elements, at the same time those elements are handled in a simplified way, in what's certainly a regression.
• Another thing that it fails to address, that seems to be too easy a conclusion for readers to come to: how is the heat system not entirely solved by just "add n radiators or heatshields"? Specially now that radiators are procedural parts.
• Your "shadow of a mountain in a sun-grazing planet" colony example is probably the worst one, since it clearly ignores atmosphere dynamics (hot stuff makes air hot, should saturate radiator output).
• When. Yes, it becomes more important and more glaring of an issue with each passing day. Re-entry heating was promised as a release feature in the media event, then as a coming soon 143 days ago.

 

• The individual system itself will be simpler while applied universally in the background to everything making the whole more complex
• Adding radiators and heatshields increases mass and EC usage though, this argument could be similarly applied to asking how anything is hard when you can just add more fuel tanks
• I believe it was implied that this was on a planet with no atmosphere since a tidally locked planet is inherently close to its host star whose stellar wind would rid it of any atmosphere
• no argument

[RocketRockington]

2 minutes ago, Master39 said:

Internal conduction between parts never* resulted in interesting gameplay in KSP1.

I was hoping for the bones of KSP1 to be improved by KSP2, not discarded for more gamified, dumbed down systems.   And fwiw I've played RP1 games where heat and internal conduction did matter, using a retuned version of KSP1's heat mechanics (realheat mod) + some extras for boiloff and such.  Both for high-mach planes and space planes, where parts had proper occlusion from airflow due to FAR and not the same silly  occlusion system ported from KSP1 that's now in KSP2, another starling display of not improving anything 

Very interesting stuff, very relevant to space.  Could still use better UI.

 

[kdaviper]

3 hours ago, RocketRockington said:

I was hoping for the bones of KSP1 to be improved by KSP2, not discarded for more gamified, dumbed down systems.   And fwiw I've played RP1 games where heat and internal conduction did matter, using a retuned version of KSP1's heat mechanics (realheat mod) + some extras for boiloff and such.  Both for high-mach planes and space planes, where parts had proper occlusion from airflow due to FAR and not the same silly  occlusion system ported from KSP1 that's now in KSP2, another starling display of not improving anything 

Very interesting stuff, very relevant to space.  Could still use better UI.

 

Let us not confuse anecdotes with actual statistical relevance.

[PDCWolf]

4 hours ago, mcwaffles2003 said:

• The individual system itself will be simpler while applied universally in the background to everything making the whole more complex
• Adding radiators and heatshields increases mass and EC usage though, this argument could be similarly applied to asking how anything is hard when you can just add more fuel tanks
• I believe it was implied that this was on a planet with no atmosphere since a tidally locked planet is inherently close to its host star whose stellar wind would rid it of any atmosphere
• no argument

•It doesn't make the whole more complex. Applying the old heating to everything would have, since that's indeed a complex system. As it stand right now, and nertea makes it sound, once you counteract the total expected heat flux, that vessel doesn't need any more attention (which in fact means the calculations keep going for no reason).

•Fighting Mass and EC has no penalty, just literally build a bigger rocket and pack more batteries, there's no cost to it.

•That's even worse, as the heated surface of the planet has enough thermal mass (obviously) to keep a shaded spot almost as hot as the rest. Radiation might be very limited, but since we have "le total flux" joke, parts touching the ground will heat up the whole spacecraft. The fun part? this entire problem is solved with "more radiators". That's probably the biggest problem with the system, we have 100.000+ possible "user stories" but all stories have the same ending: More radiators/Add a heatshield.

[mcwaffles2003]

37 minutes ago, PDCWolf said:

•It doesn't make the whole more complex. Applying the old heating to everything would have, since that's indeed a complex system. As it stand right now, and nertea makes it sound, once you counteract the total expected heat flux, that vessel doesn't need any more attention (which in fact means the calculations keep going for no reason).

•Fighting Mass and EC has no penalty, just literally build a bigger rocket and pack more batteries, there's no cost to it.

•That's even worse, as the heated surface of the planet has enough thermal mass (obviously) to keep a shaded spot almost as hot as the rest. Radiation might be very limited, but since we have "le total flux" joke, parts touching the ground will heat up the whole spacecraft. The fun part? this entire problem is solved with "more radiators". That's probably the biggest problem with the system, we have 100.000+ possible "user stories" but all stories have the same ending: More radiators/Add a heatshield.

• You're assume no conditions ever change for any ship, which is a bold assumption. 
• Wow, amazing, youve beaten every KSP ever with that strategy
• The surface on the dark side of tidally locked planets isnt hot, this is why eyeball planets are believed to exist

[mcdjfp]

5 hours ago, Master39 said:

The fact that you had to dive into Jool's atmosphere to make heat conduction between parts relevant kinda proves the point...

He may have been Jool diving, but I regularly consider the placement of parts (and more than just occlusion) when designing my Mun/Minmus shuttles and tankers. I use aerobraking to save fuel on the leg to Kerbin. The deeper I can go without breaking stuff, the fewer passes I will need.

 

My issue is the removal of a design constraint. Now only occluding low temperature parts will be necessary. And now that I think about it more, that might not even be necessary. If it is a simple have more cooling than the craft is receiving heating, then why not mount that temperature sensitive part where it will be exposed to reentry? I just need enough cooling somewhere on the vessel that it won't heat up.

[Periple]

8 minutes ago, mcdjfp said:

My issue is the removal of a design constraint. Now only occluding low temperature parts will be necessary. And now that I think about it more, that might not even be necessary. If it is a simple have more cooling than the craft is receiving heating, then why not mount that temperature sensitive part where it will be exposed to reentry? I just need enough cooling somewhere on the vessel that it won't heat up.

How are you going to make the radiators survive the aerodynamic loads of atmospheric entry?

FWIW I’ve made one (1) Eve craft where adding a couple of those curved radiators made it survivable. It was just on the limit without them. They only cool the part they’re attached to, which was a very tight design constraint.

The design of this craft would not have been affected much by the simplified thermodynamics, assuming that the radiators are subject to the same constraint (only the part they’re attached to of cooled).

Of course if you can just cover a craft with them and call it a day then that’s disappointing!

Edited July 25, 2023 by Periple

[cocoscacao]

Rereading the original post, I didn't quite understand one thing. If you're in a decently thick and warm atmo, will radiators lose some efficiency, because they are also receiving some heat from it? 

[PDCWolf]

2 hours ago, mcwaffles2003 said:

• You're assume no conditions ever change for any ship, which is a bold assumption. 
• Wow, amazing, youve beaten every KSP ever with that strategy
• The surface on the dark side of tidally locked planets isnt hot, this is why eyeball planets are believed to exist

• I'm assuming you do due diligence and get your data before departing, thus you know the max temperature where you're going, and the capabilities of your ship. Further on, I'll ask, what's stopping me from EVA-Welding or docking more radiators?
• KSP1 has a cost system that, with the right settings, is actually pretty challenge.
• The original example only cites the shade of a mountain, it's assumed that if a mountain is casting shade... there's the sun illuminating it.

[Pthigrivi]

19 minutes ago, PDCWolf said:

• KSP1 has a cost system that, with the right settings, is actually pretty challenge.

This isn't going away though. Currency is just being replaced with resources, which may in fact be more challenging.

[PDCWolf]

38 minutes ago, Pthigrivi said:

This isn't going away though. Currency is just being replaced with resources, which may in fact be more challenging.

From AMA1 and 2, resources seems to be a system based on establishing X colony on a world with resource Y and a shipping lane to wherever you want to make use of it to build part Z. How hard it is to build and expand colonies remains to be seen (though AMA2 suggests it's only interacting with a menu).