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

[Lexif]

Good going keeping this mod alive! I have three suggestions for heat shields:

1) Have the inflatable heat shield have a 'deflate' option.

I don't think an inflatable heat shield should be able to magically repackage itsself, if that's what you mean.

[NWM]

Tanks for this awesome mod, I just wish to share 2 idea of mine.

1 - heat spoilers - to protect vulnerable parts - like radial chutes

2 - "repair everyting" option in case landed on KSC - sometimes extremelly fatihuing to check a 200+ pars SSTO after each landing - and, more anoying when clears up at the next reentry: something had been missed at previous checking...

[balu0]

Same here

The mod works, but there are no flames

When I set the FX Transition as low as 5 ms to begin and 50 to full, I got a little flame, but not much.

I use FAR, btw.

Edited November 17, 2013 by balu0

[Olsson]

Since the heatshield parts for me are locked, "Part model requires an entry purchase in R&D." I'm not sure what to do. What research do I need to do to unlock the heatshields? Does the deadly re-entry script thing still run even if I don't have a heatshield? Does the standard 1 man black pod have an in-built heatshield? I can still do a re-entry with a science lab underneath my pod and it doesn't get blown up, so I'm guessing I don't need a heatshield?

[AndersW]

I am trying to install this mod, but I am having problems with "ModuleManager.dll" I already have one of those from Ferram and I can't have both at the same time. Can someone tell what needs to be done, or what I am doing wrong.

[AndersW]

I just had the same problem. I fixed it by going to R&D and researching the parts themselves from the very first slot that you start with.

I think this problem popped up because I started this career before I installed the mod, so the parts were not auto-researched for me.

[FlowerChild]

Nathan, I've been running into some very strange results where ablation seems to occur at a much greater rate when a vessel is low in the atmosphere after it is actually out of any danger from reentry. With one particular set of parameters I'm working on in tweaking a part, this is generating very strange results where no matter how strong I make the heat shield, it winds up burning up on reentry anyways.

NM on my point here. Turns out it was some weirdness in how MM was handling my changes that was causing them not to register for the part in question. Scanning through the debug log this morning I was able to correct the issue.

I'm still finding it rather odd how shields burn off more rapidly in the lower atmosphere than in the upper when they are being subjected to far less heat, but it's not directly related to the problem I was having. My apologies for any confusion there.

[Sacred Aardvark]

I am trying to install this mod, but I am having problems with "ModuleManager.dll" I already have one of those from Ferram and I can't have both at the same time. Can someone tell what needs to be done, or what I am doing wrong.

You only need one, and usually want the one with the newer date, several mods use the same dll in gamedata

[edit] apparently I'm out of date, see NathanKells response below.

Edited November 18, 2013 by Sacred Aardvark

[NathanKell]

FlowerChild: It uses exponential density in both cases. I looked for a good chunk of this morning for references on ablative loss rate on reentry and came up empty; I'm pretty sure ialdabaoth got the science right but, without references, I can't double-check.

The main point is, though, the shockwave temperature may be very high in the upper atmosphere (i.e. how fast are you pushing air molecules out of your way, due to your velocity, and thus heating htem) but the transferrence of the shockwave temperature to your craft is very low, since there are very few air molecules to push. Your major heating--and thus your major ablative shielding loss--should be a bit lower.

One thing we might check is turn on GUI fields for the various component steps in the equations (like is done for shockwave itself), and see whether TemperatureDelta is really out of whack with ablation. Ideally both should peak at the same time and stay roughly in proportion, if I understand the science correctly.

AndersW: You always want the latest ModuleManager. sarbian released MM 1.5; that's the only one you should have, and you should grab it, put it in GameData, and then clear out any module managers not named ModuleManager1.5.dll (like the one from this mod and from FAR).

Sokar408: It will correct parts with ridiculous max temperatures (i.e. most parts that don't have DRE-compatible configs). It will not, however, detect heat shields; you have to add the resources and module yourself (or bug me and I'll do it for the next DREC). Note that it does make the stock and B9 fuselages into non-ablative heat shields...

Anybody makes a ballute, I'll support it; I don't have the time to make parts myself now I'm sorry to say.

Agarax: I've considered making plug-nozzle aerospikes into heat shields, per Phil Bono's ideas. I wants me my Ithacus/ROMBUS!

metaphor: It's meant to track shockwave temperature, which in Earth's atmosphere is basically (velocity magnitude) in Kelvin. Weird but true.

Since DREC doesn't actually check part size, surface-area-based measurements aren't useful.

NWM: 1. You put something in front of a radial chute, it'll block the heat.

2. Hmm, neat idea. But you really should recover and relaunch; most of that can't be done as field repair anyway.

In other news, I'll have the revised heat shield stats for DREC v4

[FlowerChild]

FlowerChild: It uses exponential density in both cases. I looked for a good chunk of this morning for references on ablative loss rate on reentry and came up empty; I'm pretty sure ialdabaoth got the science right but, without references, I can't double-check.

Hehe...I went on a similar online fact finding mission last night as well and turned up diddly. I'm not convinced on the science though, as even just the shockwave value itself representing max tempterature that you can attain regardless of pressure (because the temperature delta between you part temperature and the shockwave "temperature" zero out the delta at a fixed point) seems off to me. I'm all for simplifications for the sake of performance and to save development time, but something seems rather fishy to me here.

The main point is, though, the shockwave temperature may be very high in the upper atmosphere (i.e. how fast are you pushing air molecules out of your way, due to your velocity, and thus heating htem) but the transferrence of the shockwave temperature to your craft is very low, since there are very few air molecules to push. Your major heating--and thus your major ablative shielding loss--should be a bit lower.

One thing we might check is turn on GUI fields for the various component steps in the equations (like is done for shockwave itself), and see whether TemperatureDelta is really out of whack with ablation. Ideally both should peak at the same time and stay roughly in proportion, if I understand the science correctly.

Yeah, I agree with you there, and I guess that's what I'm not really seeing. If you take a close look at your ablation values as you descend on reentry, you'll notice that most of the ablation seems to occur in one big lump at low altitude, beyond the point at which your craft seems to be in any real danger. That part always struck me as odd, which is why when I ran into my tweaking difficulties (since resolved), it was one of the things I began to suspect might be causing it.

It's generally around the point where I say "phew! I made it!" that the heat shield starts really burning off

Also, one other bit I'm finding a bit odd is how temperatureExponent is used differently in the two bits of code I quoted previously. In the first bit, it's applied to the delta value between shockwave and part temperature, meaning it will affect the rate of heat accumulation, whereas in the ablation equation, it's being applied straight to the shockwave value, which seems to relate more the max attainable temp.

[NathanKell]

I'm going to enable those values for debug mode, and we'll see. I think (or hope) that the _reason_ you think you're out of danger is precisely _because_ the shield finally starts ablating at high speed.

Regarding shockwave: this is because DRE doesn't actually check Cd, reference area, or mass times that to yield ballistic coefficient. So rather than use W/m^2 heating, it just uses temperature.

That said, I note that wiki indicates that reentry velocity = peak temperature in K, which does not occur when the velocity is at its highest (IIRC). So...argh. I think you're right after all.

[Zander]

I'm going to enable those values for debug mode, and we'll see. I think (or hope) that the _reason_ you think you're out of danger is precisely _because_ the shield finally starts ablating at high speed.

Regarding shockwave: this is because DRE doesn't actually check Cd, reference area, or mass times that to yield ballistic coefficient. So rather than use W/m^2 heating, it just uses temperature.

That said, I note that wiki indicates that reentry velocity = peak temperature in K, which does not occur when the velocity is at its highest (IIRC). So...argh. I think you're right after all.

If we are going to that level of technical realism do you think we could also get a proper blackening of the textures on the craft to make reentered capsules look burned. They look brand new after landing.

[ferram4]

Taking a quick look through an aerodynamics textbook of mine, I found some stuff that might be useful:

q_w = ÃÂ_{∞}^N * V_{∞}^M * C

where:

q_w = heat flux (W/cm²)

ÃÂ_{∞} = atmospheric density (kg / m³)

V_{∞} = freestream velocity (m / s)

M, N, C are constants that vary with the flow geometry.

For a stagnation point (nose of a plane, wing leading edge, heat shield):

M = 3

N = 0.5

C = 1.83 * 10^-8 * R^-0.5 * (1 - h_w / h_o)

where:

R = nose radius or equivalent (m)

h_w = mass specific enthalpy of the wall (m² / s²)

h_o = mass specific total enthalpy of the flow (m² / s²)

R can be specified for any part

h_w can be taken from the part temperature, but using atmospheric heat transfer properties:

h_w = c_p * T_w

h_o is simply a function of the flow velocity and gas properties:

h_o = c_p * T_{∞} + V² / 2

where:

c_p = specific heat at constant pressure (J / (kg * K))

T_{∞} = freestream atmospheric temperature (K)

T_w = wall temperature (K)

The exponential density is definitely wrong based on this; it should be based on a square root density. It may just be a gameplay-based decision to be honest.

I pulled this from Fundamentals of Aerodynamics, 5th edition, John D. Anderson Jr., McGraw-Hill, 2011. In the section that I pulled the above data from Anderson references:

Tauber, M. E., and Meneses, G. P., "Aerothermodynamics of Transatmospheric Vehicles," AIAA Paper 86-1257, June 1986.

Supposedly the above reference also has data for non-stagnation point configurations as well, but I haven't tried to track it down yet.

[biasuz]

I'm sorry is this question seams like a dull problem on my end.

But I've installed this mod several times and I keep missing the 2.5m heat shield.

My Command Pod Mk1-2 keeps blowing up without this part.

Is this part present in the pack or is my install corrupt?

Thanks for your time.

[Playful1510]

For some reason, when I launch, before the scene even finishes loading, parts explode from overheating, but this doesn't happen every time, even on the same ship design... Any ideas whats going on?

[Lexif]

For some reason, when I launch, before the scene even finishes loading, parts explode from overheating, but this doesn't happen every time, even on the same ship design... Any ideas whats going on?

Do you use Remote Tech 2 by any chance? I recently started using it and that's when I first got those explosions, too. I didn't get around to reproducing it. I remember this bug from earlier versions, wasn't RT involved there, too?

[NathanKell]

Hah, thanks ferram! I was going to pm you about this tonight because I figured you'd know, and...you post before I even ask. Thanks so much!

biasuz: it should appear near the top of the Structural tab. Did you install this after starting a career save? You have to go back and unlock it (or it might not have unlocked yet).

Playful1510: known issue. Working on it. I'm very sorry, but for now, revert to VAB and try again.

[Playful1510]

Lexif: Yes, actually!

NathanKell: Ok! Just wanted to let you know if you didn't already know!

[stevron]

Two of my Kerbal's who were sitting on the launch pad waiting for the mission to Duna to launch whilst I was doing corrections for another vessel both died from random parts exploding when I switched back :(

[Frederf]

I've personally set the ablative resource to 1/3rd mass per unit. The default Mark1-2 pod is 4t with 1t on shield constituting 20% of its mass. The Apollo CM for contrast had only 7% of its mass as shield.

[NathanKell]

Eh? Everything I've seen says the Apollo CM had 848kg of shielding. Plus the structural backing, presumably.

And note that the Mk1-2 pod, when you add parachutes and batteries and a docking port and RCS, is just about even with the Apollo CM minus its shield. (Remember, the Apollo CM total mass of ~5.8t was with lots of extras you have to add on to the 4 ton pod).

[FlowerChild]

q_w = ÃÂ_{∞}^N * V_{∞}^M * C

Lol...thanks dude. I couldn't help crack a smile seeing the above from the guy who made FAR

I'm going to enable those values for debug mode, and we'll see. I think (or hope) that the _reason_ you think you're out of danger is precisely _because_ the shield finally starts ablating at high speed.

You may be right here man, and it may also be related to the fiery doom effects subsiding as well, giving the impression the worst of it is over.

It "feels" off, but it's hard to pinpoint exactly what's leading to that.

EDIT: Oh, one more thing Nathan (I'm heading to bed so I'll dig into Ferram's equations tomorrow when I'm not half asleep), one pertinent piece of information that I observed is that these rapid periods of ablation seem to be accompanied by a rapid decrease in part temperature, which is kind of the opposite of what I would expect. Intuitively, I'd expect the most intense ablation to occur when heat is building up and burning away the shield, rather than it acting to actually cool the part down at the end of reentry.

Again, I could be wrong about how ablation actually works there, and I will take a closer look at the math behind it when I'm a little more sentient

Edited November 18, 2013 by FlowerChild

[Starwaster]

Lol...thanks dude. I couldn't help crack a smile seeing the above from the guy who made FAR

You may be right here man, and it may also be related to the fiery doom effects subsiding as well, giving the impression the worst of it is over.

It "feels" off, but it's hard to pinpoint exactly what's leading to that.

EDIT: Oh, one more thing Nathan (I'm heading to bed so I'll dig into Ferram's equations tomorrow when I'm not half asleep), one pertinent peace of information that I observed is that these rapid periods of ablation seem to be accompanied by a rapid decrease in part temperature, which is kind of the opposite of what I would expect. Intuitively, I'd expect the most intense ablation to occur when heat is building up and burning away the shield, rather than it acting to actually cool the part down at the end of reentry.

Again, I could be wrong about how ablation actually works there, and I will take a closer look at the math behind it when I'm a little more sentient

You're probably right, it probably should not actually cool the part.

Instead, when applying heat to the part there should be a maximum temperature that the part should not exceed so long as it has ablative material left on the shield.

(the same principle should probably apply when/if MFSC gets its own temperature handling system in that tank temperature should not exceed the lowest boiling temperature present on the tank)(assuming passive cooling schemes such as using the LH2 tank to provide cooling for the LOX tank)

[hawkwing]

Fantastic. Now my space planes explode. Not during reentry, but 500m from the KSC runway, long after I'd expect a plugin called deadly reentry to be trying to kill me. Anyone have an explanation for it? I'm not using FAR, by the way. It doesn't seem to be happening every time, either, but occasionally when I approach landing the temperature on my wingtips seems to drop to -20c or so and they'll explode. Vanilla wings.

[tygoo7]

How would I make this mod work with deadly reentry without blowing up?