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

[arkie87]

Very shallow reentries mean lower peak heating rates but but spread out for a much longer time. As you say, you cook slowly. G Force is also lower for a shallow reentry.

Steep reentries mean higher peak heating rate but for a shorter period of time. It also means higher G Forces.

So is it possible to burn up upon re-entry at 65 km at orbital speeds?

[Svm420]

I have yet to narrow down the Pfairing issue.

Otherwise I have a question. I had Roverdude's sounding rocket mod installed and made a rocket with a small payload to go on a nice high sub orbital trajectory. I had the main payload truss enclosed by his small side fairings nose cose chute on top and a tweakscaled stock heatshield on the bottom. Basically fully enclosed. I had watched the parts inside the fairing on the truss for heat. They for the most part did not gain any heat, but the exterior temp, inside the fairings mind you, was the same as the extTemp outside the fairing. Is that normal? I did have 1 occasion where a stock battery was heating up at 15km up on re entry till around 5km. It stopped heating after decoupling the heatshield and began to cool. No other parts of similar mass and closer to the shield heated in anyway, so I do not think it was conduction from the shield as that had a low temp overall as well. I was unable to check the part directly to see what factors lead to the skintemp increasing. I will try to get more concrete findings later. This was latest version you posted the dropbox link to.

[xXIndestructibleEVAXx]

Starwaster, any idea why my ships aren't burning up?

[arkie87]

Starwaster, any idea why my ships aren't burning up?

Not sure if making fun or serious

[Nansuchao]

Be careful that there are mods that interferes with the behavior of Deedly Reentry. I see many people that are unhappy cause their ships don't burn, others (like me) who needed to delete the mod and reinstall everything cause we had our payload burned for overheating while standing on the Runway or the Launchpad.

Probably there are other mod that interfere or an instability in KSP that cause this...

[xXIndestructibleEVAXx]

arkie87, I am serious. I posted 2 pages ago, he asked me a question, I answered, then he never replied back.

[Starwaster]

So is it possible to burn up upon re-entry at 65 km at orbital speeds?

I have. If I don't put a shield on something and deorbit, it burns up.

I have yet to narrow down the Pfairing issue.

Otherwise I have a question. I had Roverdude's sounding rocket mod installed and made a rocket with a small payload to go on a nice high sub orbital trajectory. I had the main payload truss enclosed by his small side fairings nose cose chute on top and a tweakscaled stock heatshield on the bottom. Basically fully enclosed. I had watched the parts inside the fairing on the truss for heat. They for the most part did not gain any heat, but the exterior temp, inside the fairings mind you, was the same as the extTemp outside the fairing. Is that normal?

If they're on the launchpad pretty much everything is going to be the same temperature. As before: The effect of fairings depends on if they set ShieldedFromAirstream = true. If they do then the part is skipped for convection heating. Other heating still applies.

I did have 1 occasion where a stock battery was heating up at 15km up on re entry till around 5km. It stopped heating after decoupling the heatshield and began to cool. No other parts of similar mass and closer to the shield heated in anyway, so I do not think it was conduction from the shield as that had a low temp overall as well. I was unable to check the part directly to see what factors lead to the skintemp increasing. I will try to get more concrete findings later. This was latest version you posted the dropbox link to.

Was heating, decoupled, stopped heating. Sounds like conduction to me. But this isn't something that boils down to theory or hypotheses. It either is or isn't, there's no Schrodinger's Cat at work, enable thermal display debugging and check the part's action menu.

arkie87, I am serious. I posted 2 pages ago, he asked me a question, I answered, then he never replied back.

Because I don't have an answer yet. You're not burning up on a craft that I pretty much duplicated along with its reentry profile but was unable to duplicate your experience. My craft exploded and everyone died. Your only change to difficulty settings was to make it 120% heating but you're still not burning up. I don't know why yet. Works for me on 100%

Maybe another mod is interfering. Reinstall fresh KSP leaving all settings alone (except graphical if you want; default resolution is fugly) with only DRE and its dependencies and try to repro again. Use Hyperedit if you want.

[arkie87]

arkie87, I am serious. I posted 2 pages ago, he asked me a question, I answered, then he never replied back.

Sorry. Wasnt sure. Some people on the forums like to be rude like that. Glad to know that wasnt your intention.

I guess i should have scrolled back and seen your post...

[xXIndestructibleEVAXx]

Okay, I just did another test (before I saw your response) with an orbit of 145x125, then I burned down to 141x20, and came in with only a mk 1-2 pod and a chute. The highest skin temp got was 480, and the gees peaked at just over 3. Still no exploding.

I'll download fresh KSP and try it out, like you said, and slowly reinstall my mods until I find the one that is causing it to not work.

[arkie87]

Starwaster: I tested new dll and cfg and it appears to rid sub-sonic heating. Out of curiosity, what was the problem?

[Starwaster]

Starwaster: I tested new dll and cfg and it appears to rid sub-sonic heating. Out of curiosity, what was the problem?

To reiterate, Kerbin does not naturally have particularly lethal levels of heating. This is a result of its very small radius which has the following impact:

1. Low initial orbital velocity at reentry interface.
   
2. Less time spent aerobraking.
   

Introducing the concept of skin (and therefore using only a portion of the part's total mass when calculating temperature increase) goes a long way to making things more dangerous but we still have to do several things to compensate for Kerbin's small size:

1. Increase the rate of heating (Convection Factor 40. And Radiation Factor 40 to compensate because re-radiating absorbed heat is an important part of thermal management during reentry)
   
2. ConvectionDensityExponent of 0.5 (I think that's what it's at now) has the effect of shifting the zone in which major heating occurs to the upper atmosphere so that it starts sooner.
   
3. A multiplier to aeroheating when calculating shockwave temperature and therefore flux. (was at 3.65)
   

#3 is the cause of subsonic heating because it applies across the board basically more than tripling your velocity when calculating heat. So I made a separate multiplier which ONLY kicks in at supersonic speeds. Currently it cannot be modified because it is hard coded. Next update will expose it to players who want to change it.

I'm working on that update but have been very busy the past couple of days so I haven't been able to put as much time into it. NathanKell has spent some time on some bugs and other coding for this update as well. I may put a preliminary dev version up

[Minwaabi]

I just got my game to be stable and I did my first reentry. Apo of 80km to a peri of 17km. Flames (graphics) started around 65km which I thought was odd, but seems to be a new feature of DRE (correct?). However, I don't think my craft heated up at all. At the very least my shield did not loose any ablation at all. The only mod I have installed that seems like it could/should affect DRE's heating is FAR. Has anyone else seen or heard of this problem or know of a solution?

[Starwaster]

I just got my game to be stable and I did my first reentry. Apo of 80km to a peri of 17km. Flames (graphics) started around 65km which I thought was odd, but seems to be a new feature of DRE (correct?). However, I don't think my craft heated up at all. At the very least my shield did not loose any ablation at all. The only mod I have installed that seems like it could/should affect DRE's heating is FAR. Has anyone else seen or heard of this problem or know of a solution?

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

[arkie87]

To reiterate, Kerbin does not naturally have particularly lethal levels of heating. This is a result of its very small radius which has the following impact:

1. Low initial orbital velocity at reentry interface.
   
2. Less time spent aerobraking.
   

Introducing the concept of skin (and therefore using only a portion of the part's total mass when calculating temperature increase) goes a long way to making things more dangerous but we still have to do several things to compensate for Kerbin's small size:

1. Increase the rate of heating (Convection Factor 40. And Radiation Factor 40 to compensate because re-radiating absorbed heat is an important part of thermal management during reentry)
   
2. ConvectionDensityExponent of 0.5 (I think that's what it's at now) has the effect of shifting the zone in which major heating occurs to the upper atmosphere so that it starts sooner.
   
3. A multiplier to aeroheating when calculating shockwave temperature and therefore flux. (was at 3.65)
   

#3 is the cause of subsonic heating because it applies across the board basically more than tripling your velocity when calculating heat. So I made a separate multiplier which ONLY kicks in at supersonic speeds. Currently it cannot be modified because it is hard coded. Next update will expose it to players who want to change it.

I'm working on that update but have been very busy the past couple of days so I haven't been able to put as much time into it. NathanKell has spent some time on some bugs and other coding for this update as well. I may put a preliminary dev version up

That answered my question as well as future questions i wanted to ask. You saved yourself some time

- - - Updated - - -

Starwaster,

Is it your official opinion that DRE's purpose (as opposed to stock game, which now includes reentry) should:

(a) simulate a "hot" 8 km/s 6000 km radius re-entry (earth)

or

( simulate, as accurately as possible, a 2 km/s 600 km radius re-entry?

If the answer is (, then perhaps re-entry heating shouldnt be that difficult unless interplanetary velocities are present?

[Starwaster]

That answered my question as well as future questions i wanted to ask. You saved yourself some time

- - - Updated - - -

Starwaster,

Is it your official opinion that DRE's purpose (as opposed to stock game, which now includes reentry) should:

(a) simulate a "hot" 8 km/s 6000 km radius re-entry (earth)

or

( simulate, as accurately as possible, a 2 km/s 600 km radius re-entry?

If the answer is (, then perhaps re-entry heating shouldnt be that difficult unless interplanetary velocities are present?

I would say closer to A than to B.

If you want B, that's easy. Set Convective / Radiation factors to 1. Set the mach heating multiplier to 1 (which you can't until next update because it's hard coded)

That should be reasonably accurate except maybe making skin thinner than it is because right now it's something like 10% of the vehicle mass which isn't very thin or realistic but most of the time it works.

And then it wouldn't be deadly.

Now, to elaborate on the deadly part, one problem that this mod has always had is perception. Even when everything works right you'll always have two camps who either find it too hard or not hard enough.

Really, the goal of this mod is that if you do everything right, you win. You get down without killing your Kerbals. If you messed something up because you built a craft that didn't have adequate protection or because a bad reentry profile was chosen then you have a punishing grueling reentry and worse case scenario, Kerbals die, ship dies, etc.

That's something I fear will always stick with this mod no matter what, even after DRE 7's code base is stable and right. It makes it hard to isolate real issues from perceptual issues but what can you do.

[Ser]

Starwaster, may be just some GUI switch between "Realistic Kerbin" and "Earth-like" model would be useful?

And btw, can crew still be killed by over-G? I had reentry with 2.5m shield facing downwards and... forgot to deploy parachutes. Hit the ground at above 100m/s, the crew pod didn't explode and the crew survived.

And one more question: do parts explode when the skin temp is exceeded or when the core temp is?

Edited May 22, 2015 by Ser

[Starwaster]

Starwaster, may be just some GUI switch between "Realistic Kerbin" and "Earth-like" model would be useful?

And btw, can crew still be killed by over-G? I had reentry with 2.5m shield facing downwards and... forgot to deploy parachutes. Hit the ground at above 100m/s, the crew pod didn't explode and the crew survived.

Consider yourself very lucky. This time.

And one more question: do parts explode when the skin temp is exceeded or when the core temp is?

When either one is exceeded. (I intend to change that for skin. When it approaches its maxTemp it will take damage like previous versions of DRE did. The more damage it takes, the more heat it lets through to the interior. That's one reason why I want less conduction between skin and part temperature. When part temperature reaches certain levels, bad things can happen, such as crew death, fuel tank explosion, etc)

[arkie87]

When either one is exceeded. (I intend to change that for skin. When it approaches its maxTemp it will take damage like previous versions of DRE did. The more damage it takes, the more heat it lets through to the interior. That's one reason why I want less conduction between skin and part temperature. When part temperature reaches certain levels, bad things can happen, such as crew death, fuel tank explosion, etc)

That is a pretty damn awesome idea...

- - - Updated - - -

I would say closer to A than to B.

If you want B, that's easy. Set Convective / Radiation factors to 1. Set the mach heating multiplier to 1 (which you can't until next update because it's hard coded)

That should be reasonably accurate except maybe making skin thinner than it is because right now it's something like 10% of the vehicle mass which isn't very thin or realistic but most of the time it works.

And then it wouldn't be deadly.

Now, to elaborate on the deadly part, one problem that this mod has always had is perception. Even when everything works right you'll always have two camps who either find it too hard or not hard enough.

Really, the goal of this mod is that if you do everything right, you win. You get down without killing your Kerbals. If you messed something up because you built a craft that didn't have adequate protection or because a bad reentry profile was chosen then you have a punishing grueling reentry and worse case scenario, Kerbals die, ship dies, etc.

That's something I fear will always stick with this mod no matter what, even after DRE 7's code base is stable and right. It makes it hard to isolate real issues from perceptual issues but what can you do.

I see. I guess that explains the reaction towards nuclearping.

Since stock KSP now includes heating, it makes sense to make DRE harder/closer to Earth's re-entry, though i do agree-- you will always have an issue with players perceived issues rather than real ones. Perhaps make it clear in the OP that this mod is now mostly intended to be harder than stock rather than more realistic than stock?

Also, a question regarding re-entry profiles: basically, it seems that ideal re-entry profiles are steep enough to slow down quickly and safely (~5 g). The issue with being too shallow is that you end up heating up without really slowing down. My question is: is this realistic? Shouldnt heating be proportional to drag force? Power = Force*Velocity, after all? Would it be more consistent / avoid this problem if heating was applied as part.drag_force*part.velocity always (regardless of which aerodynamics model was used-- stock or nuFAR)?

[Ser]

The issue with being too shallow is that you end up heating up without really slowing down.

I think there's a little inconsistency between FAR drag and DRE heat. But can't you even accelerate through the atmosphere under influence of gravity and get heated? The question is only which force is greater.

EDIT: and yes, it's crystal clear where that inconsistency come from: FAR uses actual atmospheric parameters while DRE pushes them to get higher temperatures. As a result we get much heat with low drag.

EDIT2: one can tell his own stories on why that happens, for example that the Kerbin's atmosphere is already highly ionized for some reason and that makes reentries as hot as on Earth even in low drag conditions.

Edited May 22, 2015 by Ser

[Starwaster]

Also, a question regarding re-entry profiles: basically, it seems that ideal re-entry profiles are steep enough to slow down quickly and safely (~5 g). The issue with being too shallow is that you end up heating up without really slowing down. My question is: is this realistic? Shouldnt heating be proportional to drag force? Power = Force*Velocity, after all? Would it be more consistent / avoid this problem if heating was applied as part.drag_force*part.velocity always (regardless of which aerodynamics model was used-- stock or nuFAR)?

Not really no..... peak heating typically occurs before drag force peaks. In fact, high drag vehicles take less heat than low drag ones because the shockwave detaches from the craft whereas low drag, pointier vehicles are in direct contact with the shockwave.

[arkie87]

Not really no..... peak heating typically occurs before drag force peaks. In fact, high drag vehicles take less heat than low drag ones because the shockwave detaches from the craft whereas low drag, pointier vehicles are in direct contact with the shockwave.

Is shock wave detachment simulated by DRE? Which variable accounts for this? Exposed area?

Peak heating can occur before peak drag with F*V formulation since velocity could be.higher, no?

If this approach could be made to work, it would be more consistent between aerodynamics models.

[linuxgurugamer]

I have an odd problem. I first thought it was FAR, but deleting DRE solved it:

I built a rocket using the stock fairings. When I launch it, the fairing don't seem to block the aerodynamic stuff. Parts inside the fairing explode due to heating, a satellite was knocked off the decoupler and destroyed, etc.

I replaced the stock fairing with the conic fairing from Keramzit Engineering (I think it is the Procedural Fairing mod), and the rocket was fine.

This happened on two different rockets.

I just downloaded the updated FAR (0.15.2), and I see the same thing. I also have the latest DRE installed (7.0.3)

I verified that ModularFlightIntegrator is installed, version 1.0.0

I have a lot of mods installed, so before I post a complete report, I'll make a new install with the minimal mods I need to reproduce this. I just need to know if you need this info or if you already have it.

If you only need a craft file, let me know.

This isn't a game killer since Procedural Fairings works well.

I looked at the list of issues and solved issues, didn't see anything like this.

Thanks in advance

LGG

[Starwaster]

Is shock wave detachment simulated by DRE? Which variable accounts for this? Exposed area?

Peak heating can occur before peak drag with F*V formulation since velocity could be.higher, no?

If this approach could be made to work, it would be more consistent between aerodynamics models.

No, it's not currently simulated. I've experimented with a model that sort of did but I didn't pursue it. It used the exposed area to try to find the radius of the nose . (nose in this instance meaning the radius of whatever part is facing into the shockwave)

Currently though peak heating already occurs before peak drag because it's peak drag that arrests the increase in heating.

[linuxgurugamer]

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:

@PART[KW2mSRBNoseCone]
{
    @maxTemp = 1523.15    emissiveConstant = 0.9
    {
        name = ModuleAeroReentry
        skinThicknessFactor = 0.1
        skinHeatConductivity = 0.012        skinMaxTemp = 2000
    }    
}
@PART[KW1mNoseCone]
{
    @maxTemp = 1523.15    emissiveConstant = 0.9
    MODULE
    {
        name = ModuleAeroReentry
        skinThicknessFactor = 0.1
        skinHeatConductivity = 0.012        skinMaxTemp = 2000
    }    
}

should be:

@PART[KW2mSRBNoseCone]{
    @maxTemp = 1523.15
    emissiveConstant = 0.6
    {
        name = ModuleAeroReentry
        skinThicknessFactor = 0.1
        skinHeatConductivity = 0.012
        skinMaxTemp = 2000
    }    
}
@PART[KW1mNoseCone]
{
    @maxTemp = 1523.15
    emissiveConstant = 0.6
    {
        name = ModuleAeroReentry
        skinThicknessFactor = 0.1
        skinHeatConductivity = 0.012
        skinMaxTemp = 2000
    }    
}

[01010101lzy]

I have a problem which may let me uninstall DRE...

When launching a rocket, the reentry fire starts at 20km and then lasts all the way to the top of the atmosphere, and overheated three of my four RCS thrusters on the rocket. Turning up the radiation factor just doesn't help.

KSP v1.0.2 with DRE v7.0.3 and MFI v1.0.0. FAR has just been uninstalled.