Reentry Heating (For Science!)

[ArmchairGravy]

I will say the heat system is a better implementation than I expected. It didn't kill my FPS. It's pushed up my aerobraking by 15km so aerobraking is not nearly as effective now. Stuff under a nose cone is getting heated and destroyed when launching to orbit. The heat system needs tweaked, not binned, which is a pleasant surprise.

[Kerbart]

  On 12/22/2023 at 3:10 AM, ArmchairGravy said:

I will say the heat system is a better implementation than I expected. It didn't kill my FPS. It's pushed up my aerobraking by 15km so aerobraking is not nearly as effective now. Stuff under a nose cone is getting heated and destroyed when launching to orbit. The heat system needs tweaked, not binned, which is a pleasant surprise.

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This brings back memories from KSP1 when the 0.23 souposphere was replaced with an atmosphere in 0.95. Most of the complaints about "the game being broken" came from players who, up until then, were flying with a complete disregard for atmospheric conditions. Granted, pancake-style were a practical necessity, but yanking the rocket from straight up to 45° in one second at 10km during ascent, or re-entry at 90° doing 3500 m/s were not.

Most of the players now do have some experience so I suspect that the percentage of "well what did you think what would happen during re-entry like that" complaints will be lower and legit complaints about how re-entry heating is faulty will be more prevalent, but it's still going to happen.

My only fear is that back then, Squad figured out how to balance things with like 5 patches in rapid succession. With the current release cycles it might take a year before it's tweaked to perfection.

[RaccoonTOF]

It doesn't help that parts which SHOULD be shielded, are not being shielded - especially an issue are lander (or other "space-rated-only" parts) that are behind fairings/payload bays/etc.  Re-entry heating on your mun excursion isn't really an issue, when the lander blows up in the fairings during ASCENT...

 

[tstein]

Something I noticed is hat  atmosphere density scaling does not feel right  in the heating department. At 68 km atmosphere should be very faint, but a 2500ms vessel already starts to burn very fast.  I think the main gripe  people are facing is related to that, the heating scaling up with atmosphere height needs some tuning.

[RaccoonTOF]

Even at 1500m/s, at 55k or so on ascent, the stock lander capsule will explode, behind fairings or not.  I'm sadly back to just making single-ship launch/travel/lander/return systems again, rather than attempting to duplicate Apollo-style landers in KSP2 for now.

(EDIT: And I don't even want to get started on the issues facing independent DUNA lander systems currently...)

Edited December 22, 2023 by RaccoonTOF

[Dakitess]

How do you reach orbit at all if parts are exploding at such low speed during ascent ? Only specific parts ? It might be something related to the max temp resistance the parts were given ?

[tstein]

  On 12/22/2023 at 12:41 PM, Dakitess said:

How do you reach orbit at all if parts are exploding at such low speed during ascent ? Only specific parts ? It might be something related to the max temp resistance the parts were given ?

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N never made my rocket climb so fast for starters, so I had no problem during ascent.  But aerocapture is simply impossible now, even a subtle one that would demand  a dozen  pass by  is impossible.

[JoeSchmuckatelli]

  On 12/21/2023 at 6:55 PM, Scarecrow71 said:

typical Mun return with an aerobrake capture.  From Mun orbit to a return with a Pe of ~45km, aerobraking until my Ap was low enough to just land.  I started with the heat setting at 100%.  I'll state that this is a typical return trajectory from Mun in KSP1, and this works without anything bad happening

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Did you have a heat shield? 

... 

I'll toss in my $0.02 - KSP was likely too forgiving.  I remember just dropping straight into the atmosphere from Mun and Minmus pretty much every time.  I might make a mid course once in a while but mostly it was get an escape and Intercept, lower pe to below 40k, warp and wait. 

Splash, recover, Science! 

Not entirely sure I want that level of forgiveness / notionality in 2

[tstein]

  On 12/22/2023 at 1:45 PM, JoeSchmuckatelli said:

Did you have a heat shield? 

... 

I'll toss in my $0.02 - KSP was likely too forgiving.  I remember just dropping straight into the atmosphere from Mun and Minmus pretty much every time.  I might make a mid course once in a while but mostly it was get an escape and Intercept, lower pe to below 40k, warp and wait. 

Splash, recover, Science! 

Not entirely sure I want that level of forgiveness / notionality in 2

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That is not so much the problem. problem is  at 70 km  zero heat at 69 km I am toasting

[Scarecrow71]

  On 12/22/2023 at 1:45 PM, JoeSchmuckatelli said:

Did you have a heat shield? 

... 

I'll toss in my $0.02 - KSP was likely too forgiving.  I remember just dropping straight into the atmosphere from Mun and Minmus pretty much every time.  I might make a mid course once in a while but mostly it was get an escape and Intercept, lower pe to below 40k, warp and wait. 

Splash, recover, Science! 

Not entirely sure I want that level of forgiveness / notionality in 2

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I did, in fact, have a heat shield that was supposed to protect my Mun lander upon re-entry to Kerbin.  And yet it overheated and blew up before any other parts on the lander (including the unprotected radial Science Jr.).  No matter the speed, angle, or depth of descent, the capsule overheated and blew up.  That's not just harder than KSP1; that's completely unforgiving.

The heat system is broken.  I had to turn it down to 20% to survive the same re-entry method I use in KSP1.  Even aerobraking is hit-or-miss with overheating.

[shdwlrd]

  On 12/22/2023 at 3:38 PM, Scarecrow71 said:

I did, in fact, have a heat shield that was supposed to protect my Mun lander upon re-entry to Kerbin

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Was it the inflatable heat shield? That one is bugged. There is no heat tolerance to it. 

[The Aziz]

  On 12/21/2023 at 6:55 PM, Scarecrow71 said:

So I was playing this morning, and I ended up testing a typical Mun return with an aerobrake capture.  From Mun orbit to a return with a Pe of ~45km, aerobraking until my Ap was low enough to just land.  I started with the heat setting at 100%.  I'll state that this is a typical return trajectory from Mun in KSP1, and this works without anything bad happening.  The results:

1. 100% heat:  Capsule exploded
2. 90% heat:  Capsule exploded
3. 80% heat:  Capsule exploded
4. 70% heat:  Capsule exploded
5. 60% heat:  Capsule exploded...but started to take longer than it did before
6. 50% heat:  Capsule exploded
7. 40% heat:  Capsule exploded
8. 30% heat:  Capsule nearly exploded, but it survived
9. 20% heat:  Capsule survived

The heating system is way overpowered and needs to be tweaked by the devs. 

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With Mk1 capsule? With ablative shield? If that so, you definitely encountered a bug. Cuz my return trips had no problem surviving behind the standard heatshield, even coming hot from the Mun. SAS to surface retrograde and watched the spectacle.

[stephensmat]

It's not just on re-entry. I burned up several parts on launch. Be careful of your launch speeds, folks.

[Scarecrow71]

  On 12/22/2023 at 7:56 PM, shdwlrd said:

Was it the inflatable heat shield? That one is bugged. There is no heat tolerance to it. 

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Standard heat shield.

  On 12/22/2023 at 8:21 PM, The Aziz said:

With Mk1 capsule? With ablative shield? If that so, you definitely encountered a bug. Cuz my return trips had no problem surviving behind the standard heatshield, even coming hot from the Mun. SAS to surface retrograde and watched the spectacle.

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Tin can lander.  Coming in retrograde, with heat shield, fuel tank, and engine still attached.  Tin can overheated and exploded before the fuel tank.  Before the engine.  Before I could decouple and a tally try to use the heat shield.  It simply blew up.  Every time until I got down to 20%.

[The Aziz]

The tin can never had much heat resistance even in KSP1. That's not very different here. And it's a bit wider than the shield so the fragile outer shell is exposed to plasma anyway.

Every single part has heat resistance values in their descriptions, can't blame the devs here.

[Vl3d]

  On 12/23/2023 at 1:10 AM, The Aziz said:

The tin can never had much heat resistance even in KSP1. That's not very different here. And it's a bit wider than the shield so the fragile outer shell is exposed to plasma anyway.

Every single part has heat resistance values in their descriptions, can't blame the devs here.

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You have to be specific. Lander cans have 750 K max temp, command pods have 850 K. All should explode on any orbital aero-braking reentry.

Edited December 23, 2023 by Vl3d

[The Aziz]

Unprotected, they will. Because, once again, the lander can is not fully hidden behind 1.25m shield.

[Scarecrow71]

  On 12/23/2023 at 1:45 AM, The Aziz said:

Unprotected, they will. Because, once again, the lander can is not fully hidden behind 1.25m shield.

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So why does it not blow up in KSP1?  I have never had this happen in KSP1.

And why does it overheat when things below it and connected to it don't?

[Shinzo]

  Reveal hidden contents

I just returned from the Mun without fuel to slow down I had to rely soley on heat shield and i'm glad to report it works ^^'

[The Aziz]

  On 12/23/2023 at 3:58 AM, Scarecrow71 said:

So why does it not blow up in KSP1?  I have never had this happen in KSP1.

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Well I have. And I never fiddled with heat settings, ever.

Quote from the wiki

  Quote

The main downside to the Mk1 Lander Can is its large, non-aerodynamic shape, making it unsuited for atmospheric use. Because it isn't cylindrical like other 1.25m parts, it produces a lot of drag. In addition, this shape means that it can't be protected by a Heat Shield (1.25m), since the exposed sides won't fit behind the heat shield.

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[Superfluous J]

  On 12/23/2023 at 12:33 AM, Scarecrow71 said:

Tin can lander

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Good.

Tin can lander should need extraordinary shielding to re-enter from Mun. Or LKO. It's a TIN CAN.

There's a reason the Lunar Module was left at the Moon.

  On 12/23/2023 at 3:58 AM, Scarecrow71 said:

So why does it not blow up in KSP1?

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Because KSP1 was more forgiving. And I thought it was wrong back then.

 

From the IG team themselves:

  On 12/22/2023 at 10:20 PM, Intercept Games said:

Upper atmospheres heat up and destroys parts far too quickly (new)
We don't consider this really a bug, the heat system just needs some tuning once we can take some time to gather feedback. As we said in the v0.2.0.0 patch notes, do not expect parity between KSP1 and KSP2 in this area!

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Edited December 23, 2023 by Superfluous J

[Kerbart]

  On 12/23/2023 at 12:42 PM, Superfluous J said:

Good.

Tin can lander should need extraordinary shielding to re-enter from Mun. Or LKO. It's a TIN CAN.

There's a reason the Lunar Module was left at the Moon.

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The Tin Can is what's called the "Mk I Capsule" in KSP1. You're thinking of the "Lander Can," or as it's called in KSP2, the Explorer. What Scarecrow is encountering is a bug.

[Scarecrow71]

@The Aziz

Huh.  I never read that in the wiki, but it makes perfect sense that this then should happen with the lander can.  If it is wider than the heat shield that is supposed to protect it, then yes, the sides should melt off upon re-entry.

My big issue here is that it's happening really high up in the atmosphere, and it's happening before anything else overheats.  There is also very little warning that it's happening; you look at the craft, it's fine, you look away, it's exploded.

Going to have to retest the heat settings with every capsule now, I guess.  I mean, I never had this happen in KSP1...but as has been pointed out, we shouldn't expect the same stuff to happen in KSP2 that happened in KSP1.  Although, I'd argue that this does in fact need to be tweaked so you aren't turning into plasma at 60km as that will have a negative impact on new players.

[Kerbart]

  On 12/23/2023 at 2:22 PM, Scarecrow71 said:

  I mean, I never had this happen in KSP1...but as has been pointed out, we shouldn't expect the same stuff to happen in KSP2 that happened in KSP1.  Although, I'd argue that this does in fact need to be tweaked so you aren't turning into plasma at 60km as that will have a negative impact on new players.

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If you're talking about the lander can... that one is OP in KSP1. Ironically the description in KSP1 lists not for atmospheric use (assuming it's similar to the LM it has 1mm thick aluminium walls, after all). But it does fine in the game. The KSP2 one doesn't have it in the description but behaves more realistically during atmospheric reentry. Curious.

[Mutex]

I get the vague impression the heating calculation isn't taking the altitude / atmospheric density into account. I dipped a probe into Eve's atmosphere and at 85km it was already toast. The very upper part of the atmosphere I'd expect to cause negligible heating because the air is so thin.