[1.12.*] Deadly Reentry v7.9.0 The Barbie Edition, Aug 5th, 2021

[smunisto]

First, lower the TWR on your rockets.

Second, post a link to your output_log.

Third, do you have fairings?

Fourth - craft file with fully stock install, fully stock craft reproducing the same problem 100% of the time.

[Minwaabi]

What craft and what shield? And which version of FAR, the very latest? (Ferri I think it's called?)

I apologize. That's a stupid mistake on my part I should have caught. I guess ckan and avc have spoiled me into not checking for updates more manually. Everything works fine now. Thanks.

Also. Wow. Um ... that was a little hotter than I expected. I've played with DRE for a while and rarely (if ever) have used more than half my ablation on reentry. I came through reentry with 0.9 ablation units left on the 1.25 m 100 point Mk-1 pod's bobcat heat shield. That was certainly more exciting than usual.

This leads me to three questions: What is the appropriate reentry profile from LKO? Will a transkerbin injection from the Mun or Minmus even work? How can you add more than one shield's worth of ablation safely (and should you try to do this)? I mean you can always add more shields, but should you try to eject them before they explode, or just let them explode and hope they don't break something/flip the pod?

[steve_v]

* ~20KM pe works for me.

* I've been re-entering direct from Mun return, a mk.1 pod uses all its ablator & gets pretty hot. But it's survivable... and my re-entry profile probably isn't ideal.

[smunisto]

On a side note, I still seem to be having some convection heating problems...or at least that's what I think it is. Using DRE 7.0.3 with Starwaster's updated DLL and .cfg.

A good thing to report was that parts within PF no longer almost spontaneously explode with the updated DLLs and Procedural Fairings.

However I still keep getting cheese-made parts explode in a relatively normal ascent. For example the stock micro-landing struts get destroyed due to heating before I even finish setting the apo during ascent.

I don't understand, even if convective(heat transmitted from one part to another, right?) heating with DRE is supposed to be realistic with the part skin system, I don't get how burning the first stage engine for 2 mins can overheat a part that is on the topmost of the rocket. Realistically there is some heat shielding between stages, right? Isn't it the same in KSP with decouplers? Shouldn't they at least limit any heat going through them by some percentage?

I don't really understand the technical data related to heating in 1.0, I remember someone explained it somewhere(maybe Starwaster, but I can't seem to find it), but here's a few screens and an output log.

Output_log

https://bg3.biz/cloud/index.php/s/E0SujuioB46VDjl

https://bg3.biz/cloud/index.php/s/6UpCo4UU7prooXr

https://bg3.biz/cloud/index.php/s/xKrzIq5QapC3BFI

[Starwaster]

Just an FYI, 7.0.3 still has the error in the KWRocketry cfg file (following is only a short part of the file) I see that the emissiveConstant is different between the two below, I'm not sure which is right:

The second one looks like you got it from the repository files. That one is more recent than the one in 7.0.3 and you should use it.

I'm not sure that's a factor in your other issue or not; it causes parse errors that prevents the rest of the KWR config from being processed but past that I don't know.

Re: your other issue, Are you using ModularFlightIntegrator from CKAN? If so try using one from either FAR or DRE. (and if that's it then CKAN still has a bad version.... wth)

I apologize. That's a stupid mistake on my part I should have caught. I guess ckan and avc have spoiled me into not checking for updates more manually. Everything works fine now. Thanks.

Also. Wow. Um ... that was a little hotter than I expected. I've played with DRE for a while and rarely (if ever) have used more than half my ablation on reentry. I came through reentry with 0.9 ablation units left on the 1.25 m 100 point Mk-1 pod's bobcat heat shield. That was certainly more exciting than usual.

This leads me to three questions: What is the appropriate reentry profile from LKO? Will a transkerbin injection from the Mun or Minmus even work? How can you add more than one shield's worth of ablation safely (and should you try to do this)? I mean you can always add more shields, but should you try to eject them before they explode, or just let them explode and hope they don't break something/flip the pod?

I do 20km pe. Any higher and you run the risk of going to the hot place.

Stacking shields is something that I've found to be dangerous. The bottom most one tends to get too hot and conducts enough heat into the second one that it starts undergoing pyrolysis and burning up valuable heat shield before you actually need it.

[Minwaabi]

Thanks. Just tried another reentry. And I noticed that this time, I lost some ablator on my fairly reasonable ascent. Should it loose ablator when it is not exposed to the air? (And various parts of the rocket were getting very hot). Any idea of what values might make that a little more forgiving? I know there is a convection factor, a radiation factor, and a ConvectionDensityExponent, but what does changes to those values do? (Particularly ConvectionDensityExponent). Does a CDE of .4 make heating start lower or higher than 60km?

[Psycho_zs]

With I've tested DRE version 7.0.3 with NFE and the following code:

@PART
[*]:HAS[@MODULE[ModuleGenericRadiator]]:FINAL {
    @MODULE[ModuleAeroReentry]{
        @skinHeatConductivity = 1
        @skinThicknessFactor = 0.9
        @skinMaxTemp = 1900
    }
    @maxTemp=1900
}

Skin and internal temperature now level pretty good, that is fixed.

But radiators are still blow up somewhere around 700 and skinThicknessFactor does not seem affecting skin thermal mass ratio at all.

(edited @maxTemp, nothing changed)

Edited May 22, 2015 by Psycho_zs

[Starwaster]

Thanks. Just tried another reentry. And I noticed that this time, I lost some ablator on my fairly reasonable ascent. Should it loose ablator when it is not exposed to the air? (And various parts of the rocket were getting very hot). Any idea of what values might make that a little more forgiving? I know there is a convection factor, a radiation factor, and a ConvectionDensityExponent, but what does changes to those values do? (Particularly ConvectionDensityExponent). Does a CDE of .4 make heating start lower or higher than 60km?

Ablative shields lose material anytime their temperature is over their configured threshold. Which for all stock & DRE shields is set at 400 or 500. (it was 500 before but I lowered it to 400 and I think that's what it is for 7.0.3 but it's probably going to bump back up to 500)

ConvectionFactor and the others are multiplicative. The amount of convective flux is multiplied by ConvectionFactor and is set to 40. In theory that does mean 40 times the heat but because everything is based on a temperature delta it really just means that you reach some equilibrium temperature 40x faster. Unless you explode first.

ConvectionDensityExponent: part of the convection flux equation multiplies by density^ConvectionDensityExponent. That means you get much more flux in the upper atmosphere. The effect diminishes until its non existent as density reaches unity.

So the simple answer is that CDE of 0.4 makes heating start higher in the atmosphere

With I've tested DRE version 7.0.3 with NFE and the following code:

@PART
[*]:HAS[@MODULE[ModuleGenericRadiator]]:FINAL {
    @MODULE[ModuleAeroReentry]{
        @skinHeatConductivity = 1
        @skinThicknessFactor = 0.9
        @skinMaxTemp = 1900
    }
    @maxTemp=1900
}

Skin and internal temperature now level pretty good, that is fixed.

But radiators are still blow up somewhere around 700 and skinThicknessFactor does not seem affecting skin thermal mass ratio at all.

(edited @maxTemp, nothing changed)

Let me see your ModuleManager.ConfigCache so I can see what the part's end result is. (you might want to take a look at it yourself if you haven't already)

Uhm... instead of skinThicknessFactor, use skinThermalMassModifier. Give it a value of 10. That's not really the right way around this but it should do the job. I think the right way around this is a property in there that bypasses the system for parts that basically are low mass and already exposed in their entirety to the airflow.

[linuxgurugamer]

The second one looks like you got it from the repository files. That one is more recent than the one in 7.0.3 and you should use it.

I'm not sure that's a factor in your other issue or not; it causes parse errors that prevents the rest of the KWR config from being processed but past that I don't know.

Re: your other issue, Are you using ModularFlightIntegrator from CKAN? If so try using one from either FAR or DRE. (and if that's it then CKAN still has a bad version.... wth)

I am using the second file, was just letting you know since a previous post said it was fixed in 7.0.3

Re the ModularFlightIntegrator, i thought I had replaced it with the one from FAR, but I'll try again.

Thanks

LGG

- - - Updated - - -

I am using the second file, was just letting you know since a previous post said it was fixed in 7.0.3

Re the ModularFlightIntegrator, i thought I had replaced it with the one from FAR, but I'll try again.

Thanks

LGG

I just tried it again using the ModularFlightIntegrator I copied from the DRE 7.0.3 file.

No go, it still happened.

LGG

- - - Updated - - -

I am using the second file, was just letting you know since a previous post said it was fixed in 7.0.3

Re the ModularFlightIntegrator, i thought I had replaced it with the one from FAR, but I'll try again.

Thanks

LGG

- - - Updated - - -

I just tried it again using the ModularFlightIntegrator I copied from the DRE 7.0.3 file.

No go, it still happened.

LGG

Just did the same using the ModularFlightIntegrator from the FAR 0.15.2 file

No change, the fairing still doesn't seem to work when FAR is installed.

I'm not going to be around all weekend, so if you need something from me for debugging, send me a PM and I'll see it Monday evening.

LGG

[Starwaster]

Just did the same using the ModularFlightIntegrator from the FAR 0.15.2 file

No change, the fairing still doesn't seem to work when FAR is installed.

I'm not going to be around all weekend, so if you need something from me for debugging, send me a PM and I'll see it Monday evening.

LGG

Sounds to me like FAR doesn't like the stock fairings.... I have a feeling that the actual 'shell' isn't visible to FAR. Have you checked to see if it generates voxels in the VAB?

Also check the FAR thread to see what they say about it.

[Gryphon]

The travails of folks ascending too fast has inspired me to write

The MET +59 Seconds Song

[dlrk]

Anyone got recommended settings for use with SKY rescale?

[Svm420]

Is this normal? The part massively cools down if I open the cargo bay in flight at mach 1.

[NathanKell]

arkie87: KSP itself simulates detached shockwaves (a 0.5 multiplier to convective heating behind the shockwave). This is why reentering spaceplanes belly-first is survivable and nose-first isn't.

Starwaster: Actually, a 1.0 multiplier to convection is a bit lower than real. I've been trying to get real numbers for RO...

[Psycho_zs]

Here is a part of MM config cache regarding one of the radiators:

UrlConfig
{
name = radiator-universal-1
type = PART
parentUrl = HeatControl/Parts/Radiators/radiator-universal-1/radiator-universal-1
url = HeatControl/Parts/Radiators/radiator-universal-1/radiator-universal-1/radiator-universal-1
PART
{
name = radiator-universal-1
module = Part
author = ChrisAdderley
mesh = radiator-universal-1.mu
rescaleFactor = 1
TechRequired = heatManagementSystems
entryCost = 14000
node_attach = 0.0, -0.00, 0.00, -1.0, 0.0, 0.0
cost = 3500
category = Utility
subcategory = 0
title = XR-550 Standardized Heat Radiator
manufacturer = Kerb Kastra Inc.
description = Attach this deployable heat radiator to cool parts.
attachRules = 0,1,0,0,1
mass = 0.19
dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.2
angularDrag = 1
crashTolerance = 4
maxTemp = 1900
thermalMassModifier = 1.0
emissiveConstant = 1.0
heatConductivity = 0.001
bulkheadProfiles = srf
MODULE
{
name = ModuleGenericRadiator
animationName = Radiator_Extend
sunTracking = true
raycastTransformName = LinkRotator
pivotName = LinkRotator
isBreakable = true
HeatAnimation = RadiatorMediumUniversal_Heat
HeatTransformName = MediumUniversalRadiator
Emissive = 0.7
EmissiveExtended = 1.0
Area = 1.17
AreaExtended = 4.31
Radiation = 150
RadiationExtended = 1100
}
MODULE
{
name = BBModule
}
MODULE
{
name = ModuleAeroReentry
skinHeatConductivity = 0.12
}
MODULE
{
name = GeometryPartModule
}
MODULE
{
name = FARAeroPartModule
}
MODULE
{
name = FARPartModule
}
}
}

[Starwaster]

Here is a part of MM config cache regarding one of the radiators:

UrlConfig
{
name = radiator-universal-1
type = PART
parentUrl = HeatControl/Parts/Radiators/radiator-universal-1/radiator-universal-1
url = HeatControl/Parts/Radiators/radiator-universal-1/radiator-universal-1/radiator-universal-1
PART
{
name = radiator-universal-1
module = Part
author = ChrisAdderley
mesh = radiator-universal-1.mu
rescaleFactor = 1
TechRequired = heatManagementSystems
entryCost = 14000
node_attach = 0.0, -0.00, 0.00, -1.0, 0.0, 0.0
cost = 3500
category = Utility
subcategory = 0
title = XR-550 Standardized Heat Radiator
manufacturer = Kerb Kastra Inc.
description = Attach this deployable heat radiator to cool parts.
attachRules = 0,1,0,0,1
mass = 0.19
dragModelType = default
maximum_drag = 0.2
minimum_drag = 0.2
angularDrag = 1
crashTolerance = 4
maxTemp = 1900
thermalMassModifier = 1.0
emissiveConstant = 1.0
heatConductivity = 0.001
bulkheadProfiles = srf
MODULE
{
name = ModuleGenericRadiator
animationName = Radiator_Extend
sunTracking = true
raycastTransformName = LinkRotator
pivotName = LinkRotator
isBreakable = true
HeatAnimation = RadiatorMediumUniversal_Heat
HeatTransformName = MediumUniversalRadiator
Emissive = 0.7
EmissiveExtended = 1.0
Area = 1.17
AreaExtended = 4.31
Radiation = 150
RadiationExtended = 1100
}
MODULE
{
name = BBModule
}
MODULE
{
name = ModuleAeroReentry
skinHeatConductivity = 0.12
}
MODULE
{
name = GeometryPartModule
}
MODULE
{
name = FARAeroPartModule
}
MODULE
{
name = FARPartModule
}
}
}

Oh crap I'm getting senile. Of course your config wasn't going to work... you're using operators that modify existing fields instead of adding them. So if they don't exist they can't be modified. Though the skinHeatConductivity probably should have been changed. Try using this instead. It'll insert the needed module before DRE tries to add it. (note that in the next update, DRE will not add the base module via configs so you will need it this way when that updae goes through)

@PART
[*]:HAS[@MODULE[ModuleGenericRadiator]]:FOR[DeadlyReentry] 
{
    MODULE
	{
		name = ModuleAeroReentry
		skinHeatConductivity = 1
		skinThicknessFactor = 0.9
		skinMaxTemp = 1900
    }
	@maxTemp=1900
}

[linuxgurugamer]

Sounds to me like FAR doesn't like the stock fairings.... I have a feeling that the actual 'shell' isn't visible to FAR. Have you checked to see if it generates voxels in the VAB?

Also check the FAR thread to see what they say about it.

Well, if I delete FAR, it still happens, but if I delete DRE, it doesn't. In other words, I delete DRE, and it works properly. but if I delete FAR and leave DRE, it doesn't work.

[arkie87]

arkie87: KSP itself simulates detached shockwaves (a 0.5 multiplier to convective heating behind the shockwave). This is why reentering spaceplanes belly-first is survivable and nose-first isn't.

Starwaster: Actually, a 1.0 multiplier to convection is a bit lower than real. I've been trying to get real numbers for RO...

I guess belly first results in detached shockwave and nose first is oblique shock wave? Makes sense.

Does KSP calculate oblique shockwaves i.e. using oblique shockwave angle formula to see if parts are protected or not?

If so, i think that explains the results obtained in this thread: http://forum.kerbalspaceprogram.com/threads/117511-Serious-Bug-in-Convective-Aerodynamic-Heating

Does DRE simulate detached shockwaves, given it does its own convective heating calculations?

- - - Updated - - -

Stacking shields is something that I've found to be dangerous. The bottom most one tends to get too hot and conducts enough heat into the second one that it starts undergoing pyrolysis and burning up valuable heat shield before you actually need it.

How does the bottom one get too hot? You mentioned that pyrolysis is 400 or 500 degrees, so shouldnt the first one (with convective flux) ablate enough mass to keep temperature equal to 400 or 500 degrees until all ablator is gone? If thats the case, the first heat shield wont heat up hot enough to cause the second heat shield to ablate (since it will be maintained at pyrolysis temperature)? Or is the peak ablator rate limited, such that the first ablator can heat up above its pyrolysis temperature?

alternatively, you can just reduce thermal conductivity of heat shield part in order to prevent heat conduction from part to part and allow stacking of heat shields.

Edited May 22, 2015 by arkie87

[Starwaster]

Well, if I delete FAR, it still happens, but if I delete DRE, it doesn't. In other words, I delete DRE, and it works properly. but if I delete FAR and leave DRE, it doesn't work.

I can't reproduce that, sorry. I made a rocket with stock fairing, put some stuff in it and and hyper edited it to an orbit at an altitude of 60km. Everything inside was shielded. The only issue I saw with it was that the payload STAYED shielded after jettisoning the fairing. (which is a stock problem unrelated to your reported issue AFAIK)

How does the bottom one get too hot? You mentioned that pyrolysis is 400 or 500 degrees, so shouldnt the first one (with convective flux) ablate enough mass to keep temperature equal to 400 or 500 degrees until all ablator is gone? If thats the case, the first heat shield wont heat up hot enough to cause the second heat shield to ablate (since it will be maintained at pyrolysis temperature)? Or is the peak ablator rate limited, such that the first ablator can heat up above its pyrolysis temperature?

alternatively, you can just reduce thermal conductivity of heat shield part in order to prevent heat conduction from part to part and allow stacking of heat shields.

It still can (not necessarily DOES... YMMV) get hot enough that it cooks the other shield which can ablate away before it can be used

[arkie87]

It still can (not necessarily DOES... YMMV) get hot enough that it cooks the other shield which can ablate away before it can be used

Shouldnt the ablating heat flux be enough to limit temperature to pyrolysis temperature (i suppose numerically this isnt possible since temperature is calculated explicitly)? Or should temperature be reset to equal pyrolysis temperature?

[Svm420]

My jet engines are exploding at 750-800K temp 6-700K skinTemp aprox mach 1.15 10km alt. Here are logs and mm cache. Also did you see my post on pg424 about the barometer inside a cargobay?

Edited May 22, 2015 by Svm420

[Starwaster]

Shouldnt the ablating heat flux be enough to limit temperature to pyrolysis temperature (i suppose numerically this isnt possible since temperature is calculated explicitly)? Or should temperature be reset to equal pyrolysis temperature?

No, IRL, for something like AVCOAT 5026 (what Apollo used), pyrolysis starts at something like 400 but the surface of the shield can reach 2700 Celsius.

I forget what temperature pyrolysis actually peaked at... just totally guestimating here... something like 800. It was a range of a few hundred. Surface still gets much hotter than that

[Starwaster]

My jet engines are exploding at 750-800K temp 6-700K skinTemp aprox mach 1.15 10km alt. Here are logs and mm cache. Also did you see my post on pg424 about the barometer inside a cargobay?

I'l look into the jet engines. Admittedly I don't 'plane' a lot... I did try a few jets and they worked ok. Not sure I saw the barometer issue. Which cargobay was it? one of the stock ones or someone else's and is FAR installed? (which I guess I'll find out when I look at the logs but...)

[Svm420]

I'l look into the jet engines. Admittedly I don't 'plane' a lot... I did try a few jets and they worked ok. Not sure I saw the barometer issue. Which cargobay was it? one of the stock ones or someone else's and is FAR installed? (which I guess I'll find out when I look at the logs but...)

It was the stock service bay with vens stock revamp. Stock barometer aswell. Yes to FAR. My barometer issue

[Motokid600]

Having an issue on Linux x64. Completely stock, fresh install. Cant attach any heatshields to anything it seems. With some work with the mouse i can get the parts to flash green, but its difficult.

Player.log

KSP.log