Starwaster

[1.8.1] Deadly Reentry v7.7.4 The Maat Edition, Nov 6th, 2019

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I decided to test out your beta (6.5.2), so here's some feedback. :) I tried it with the 64k mod, with FAR. On Normal settings, a return from Minmus (around 8 km/s) caused my heatshield to overheat and explode within seconds after touching the upper atmosphere, even with an extremely shallow atmosphere-skimming trajectory. Easy setting was even worse.

Haven't tried much else yet, but I'll post again if I find anything significant.

Sorry, some of the settings were screwy on that last release. It'll be fixed on the next one (which I'm still plugging away on and have made some progress)

In the settings menu (while in Flight Mode), click 'Enable Debug Menu'. I'm guessing here for 64k but it shouldn't be TOO far off from RSS settings:

Set the first 4 options to 1

Set Multiplier to 2.41 - 8.3 (mainly to offset the excessively fast heat dissipation that stock KSP has)

the ablation metric probably also needs adjusting (thinking 10x its current value) and can only be altered by editing the config files (EasySettings.cfg, DefaultSettings.cfg and HardSettings.cfg)

Only do that last bit if it seems like the shield is lasting too long.

whats "lead ballast" on the inflatable heatshied?

It's to make the shield nose heavy if it flips uncontrollably.

But if you're using the latest beta, you SHOULD find it a lot less flippy. I made some extensive changes to the inflatable's configs. If using stock / SDF drag then its values are more precisely calibrated than they've ever been before and if using FAR then it removes any last vestiges of stock drag (i.e. the animation2value module that modifies drag when inflated) (just realized that I need to make that change for NEAR as well)

NEAR users click here for updated inflatable shield config

Edited by Starwaster

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Hello..

Not sure if this is a bug or something expected: I've launched the forward (crew) component with the inflatable heat shield separate from the propulsion section and docked them in space.

The problem is that the parts on the propulsion section don't seem to be protected. Even at a shallow pass through Kerbin's atmosphere several parts are being burned off.

5XIe6ual.png

gYslqz3l.png

Assembled craft in the VAB

AW7KGF0l.png

Just the propulsion unit with an inflated heat shield. Everything should be safe behind.

The parts on the Cupola and the 8 canisters attached on the propulsion module are part of the mod BTSM.

Thanks for any advice..

cd\

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Hello..

Not sure if this is a bug or something expected: I've launched the forward (crew) component with the inflatable heat shield separate from the propulsion section and docked them in space.

The problem is that the parts on the propulsion section don't seem to be protected. Even at a shallow pass through Kerbin's atmosphere several parts are being burned off.

http://i.imgur.com/5XIe6ual.png

http://i.imgur.com/gYslqz3l.png

Assembled craft in the VAB

http://i.imgur.com/AW7KGF0l.png

Just the propulsion unit with an inflated heat shield. Everything should be safe behind.

The parts on the Cupola and the 8 canisters attached on the propulsion module are part of the mod BTSM.

Thanks for any advice..

cd\

Maximum shielding distance is 10 meters to any part (whether it is attached to the craft you want shielded or not, meaning you are still shielded by jettisoned pieces until they drift more than 10 meters away)

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Sorry, some of the settings were screwy on that last release. It'll be fixed on the next one (which I'm still plugging away on and have made some progress)

In the settings menu (while in Flight Mode), click 'Enable Debug Menu'. I'm guessing here for 64k but it shouldn't be TOO far off from RSS settings:

Set the first 4 options to 1

Set Multiplier to 2.41 - 8.3 (mainly to offset the excessively fast heat dissipation that stock KSP has)

the ablation metric probably also needs adjusting (thinking 10x its current value) and can only be altered by editing the config files (EasySettings.cfg, DefaultSettings.cfg and HardSettings.cfg)

Only do that last bit if it seems like the shield is lasting too long.

At the time I was able to get away with adjusting the density exponent to 0.9, which kept the explosions to only the expected bits, though the shield only ablated 1 of its 250 points.

I'll test with those settings in the future. Just figured I'd report my findings as any good beta tester should. :)

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Maximum shielding distance is 10 meters to any part (whether it is attached to the craft you want shielded or not, meaning you are still shielded by jettisoned pieces until they drift more than 10 meters away)

Thanks. 11.3m from tip of heatshield to docking port.

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At the time I was able to get away with adjusting the density exponent to 0.9, which kept the explosions to only the expected bits, though the shield only ablated 1 of its 250 points.

I'll test with those settings in the future. Just figured I'd report my findings as any good beta tester should. :)

And I'd give you a cookie if I had any.

Ahhhh, who am I fooling. I'm a mean greedy old man and I'd probably eat them all if I had any.

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@DeathEngineering Your craft does look a bit too tall for that shield. They have these 7 meter shield from chaka monkey that provide more coverage. Beware with those you must give them lead or youll flip

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Hey all,

I've been tinkering around in 10x Kerbol and I have been finding my space craft are burning up at 116km up even from a near circular orbit (v~=6,800m/s). This includes heat shielded parts like the Mk I pod.

Are there any adjustments that I should make to avoid this happening?

Thanks,

Zap

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Hey all,

I've been tinkering around in 10x Kerbol and I have been finding my space craft are burning up at 116km up even from a near circular orbit (v~=6,800m/s). This includes heat shielded parts like the Mk I pod.

Are there any adjustments that I should make to avoid this happening?

Thanks,

Zap

Sounds like your DRE settings are too aggressive. What version are you running?

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Starwaster - I have had the same issue as jab136 (While visual heating effects are fine, the ablative shielding doesn't get hot enough to ablate). I tried your updated hard settings config, but reentry still isn't deadly =).

I'm playing stock Kerbin with FAR and your newest beta release.

Any suggestions?

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Starwaster - I have had the same issue as jab136 (While visual heating effects are fine, the ablative shielding doesn't get hot enough to ablate). I tried your updated hard settings config, but reentry still isn't deadly =).

I'm playing stock Kerbin with FAR and your newest beta release.

Any suggestions?

Heat multiplier on hard should be 20 (just like on normal). The beta release still has it set at 1.

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Heat multiplier on hard should be 20 (just like on normal). The beta release still has it set at 1.

Thanks

EDIT: I changed the HeatMultiplier to 20 in the .cfg. Now my issue is reversed - no visual effects, but lots of heat-shield ablatement.

Edited by hjrrockies

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If you're referencing the Kerbal deaths on the landing breakup of one of his spaceplanes, if definitely looked lethal--at least to me. Keep in mind that that was a massive craft, and what might look and a hard nose wheel bump could have been a pretty lethal 15-25m drop.

I know this is entirely off-topic by now ( :P) , but yes, it makes more sense now. Could it really be a 25m drop? I surely can't tell myself, I always had a problem with sizes and scaling.

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Starwaster - it might be helpful to have some kind of tutorial/explanation of how to do a safe reentry using this mod. I see a lot of posts saying they come in very shallow approaches and are still burning up. I had the same misconception about reentry, thinking that shallow reentry = safe reentry (until I googled it). Using DRE (and in real life), if reentry is too shallow you will run out of ablative shielding and burn up. If reentry is too steep, G forces will kill the crew*. So the trick is to have your approach in the window between running out of shielding (too shallow) and G force death (too steep). From LKO (~75k Ap), the lower your Pe is the safer it is because your reentry speed is not enough for a G force death*. After a certain Ap height/reentry speed, G force death becomes possible and you have to find the safe window. And the window gets smaller the faster your reentry is, until at a certain speed there is no possible angle where your crew will survive.

EDIT: Probably also worth mentioning that heavier craft will need shallower approaches to reach safe parachute speeds, which is why the wider shields have more shielding.

*Depending on your drag. This is assuming your craft has enough drag to reach safe parachute speeds.

Edited by TCFirebird

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I changed the HeatMultiplier to 20 in the .cfg. Now my issue is reversed - no visual effects, but lots of heat-shield ablatement.

Visual effects are calculated separately than heat effects. Visual effects don't start until air density reaches 0.65 (you can change this in the config), but heat/ablation will start almost immediately upon entering the atmosphere. If you're running out of ablation shielding, try a steeper approach (see above).

Edited by TCFirebird
visual effects correction

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Thanks

EDIT: I changed the HeatMultiplier to 20 in the .cfg. Now my issue is reversed - no visual effects, but lots of heat-shield ablatement.

First things first: Don't edit anything in any .cfg (exception, custom.cfg is safe to edit, but don't do it anyway because....) all of those settings can be altered in-game. When you are in flight mode, click the DRE icon (looks like a little space capsule)

Second, in the beta, heatMultiplier is set to 1 because of a new heating model in the beta. As an alternative, I suggest changing densityExponent. Change it to a lower number. The lower you set it, the higher the altitude that you experience heating.

Third, when you change densityExponent, also change FX Density Exp (FX Density Exponent) to match. As a personal preference, I like setting it to Density Exponent +0.05. That will giver you wispier softer flames when the heating starts to be noticeable but still turn into really ferocious flames when heating gets serious.

Other things that control when you see flames is Begin At / Full At (under F/X Transition). Those are the velocities where flames start and where they max out. (modified by density)

In other news, I'm making progress on the next update. It'll have an extra setting button to enable the new heating model with proper settings without messing up the original three difficulty settings.

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Starwaster - it might be helpful to have some kind of tutorial/explanation of how to do a safe reentry using this mod. I see a lot of posts saying they come in very shallow approaches and are still burning up. I had the same misconception about reentry, thinking that shallow reentry = safe reentry (until I googled it). Using DRE (and in real life), if reentry is too shallow you will run out of ablative shielding and burn up. If reentry is too steep, G forces will kill the crew*. So the trick is to have your approach in the window between running out of shielding (too shallow) and G force death (too steep). From LKO (~75k Ap), the lower your Pe is the safer it is because your reentry speed is not enough for a G force death*. After a certain Ap height/reentry speed, G force death becomes possible and you have to find the safe window. And the window gets smaller the faster your reentry is, until at a certain speed there is no possible angle where your crew will survive.

EDIT: Probably also worth mentioning that heavier craft will need shallower approaches to reach safe parachute speeds, which is why the wider shields have more shielding.

*Depending on your drag. This is assuming your craft has enough drag to reach safe parachute speeds.

People have a sense of the angles that are used for Earth reentry and expect the optimum angle for Kerbin to be similar. It sounds like at stock-Kerbin-scale speeds, the optimum approach is a lot steeper than it is for Earth, so you may have to unlearn some of the information you know that's correct for Earth.

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People have a sense of the angles that are used for Earth reentry and expect the optimum angle for Kerbin to be similar. It sounds like at stock-Kerbin-scale speeds, the optimum approach is a lot steeper than it is for Earth, so you may have to unlearn some of the information you know that's correct for Earth.

In general, that is true. You can get away with steeper reentries over Kerbin than you would over Earth IRL. I think in part that is because Kerbin has had to be made more dangerous than it would be IRL. It's a very small planet with a very thin atmospheric envelope. (thin as in only 69 km from atmospheric edge to ground ASL. Not thin as in low pressure). It's only 2-3 minutes to landing, or at least until you reach a safe velocity.

Another reason Kerbin reentries are not deadly is because the reentry velocity is much lower than Earth, and as has been said constantly over and over, reentry temperatures are linked to velocity.

There's also a third reason that isn't much talked about, at least not except in broad terms about the unrealistic heating model that KSP uses. More specifically, crafts / parts are constantly trying to shed heat through dissipation. Unlike conductivity, dissipation does take into account external temperatures such that a part can't shed heat to an environment with a hotter temperature. But we have no way of communicating that to the base code. DRE might think that the environment outside is a toasty 2000 degrees but KSP thinks it's only -20 degrees C and so the part will shed heat. I've tried experimenting with reducing the dissipation values so that parts don't shed heat and the results were catastrophic because DRE was written around a system where parts are constantly trying to shed heat. So turning down dissipation results in rockets that explode during launch much more frequently than they ever did before. Not good.

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I got a fresh beta release to make sure I had the right files and I didn't change them at all. Coming from LKO, temperatures don't get hot enough to start ablation (< 650C), on both hard and normal. Out-of-the-box hard settings are actually cooler than normal settings because of the "Use alternate density" option. If I uncheck that for hard, temperatures are about the same as normal.

People have a sense of the angles that are used for Earth reentry and expect the optimum angle for Kerbin to be similar. It sounds like at stock-Kerbin-scale speeds, the optimum approach is a lot steeper than it is for Earth, so you may have to unlearn some of the information you know that's correct for Earth.

Coming from low Kerbin orbit (<80km), the only way to get a steep approach is to reduce your orbital speed, so the steeper your approach is the slower you're going and therefore less heat/Gs. There isn't enough time for gravity acceleration. I believe this would apply for Earth also, but the delta V requirements would be much higher (impractical). Coming from the Mun/Moon on the other hand, you have to balance between too steep and too shallow.

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I got a fresh beta release to make sure I had the right files and I didn't change them at all. Coming from LKO, temperatures don't get hot enough to start ablation (< 650C), on both hard and normal. Out-of-the-box hard settings are actually cooler than normal settings because of the "Use alternate density" option. If I uncheck that for hard, temperatures are about the same as normal.

Coming from low Kerbin orbit (<80km), the only way to get a steep approach is to reduce your orbital speed, so the steeper your approach is the slower you're going and therefore less heat/Gs. There isn't enough time for gravity acceleration. I believe this would apply for Earth also, but the delta V requirements would be much higher (impractical). Coming from the Mun/Moon on the other hand, you have to balance between too steep and too shallow.

Try reducing Density Exponent even further, like to 0.5

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More specifically, crafts / parts are constantly trying to shed heat through dissipation. Unlike conductivity, dissipation does take into account external temperatures such that a part can't shed heat to an environment with a hotter temperature. But we have no way of communicating that to the base code. DRE might think that the environment outside is a toasty 2000 degrees but KSP thinks it's only -20 degrees C and so the part will shed heat. I've tried experimenting with reducing the dissipation values so that parts don't shed heat and the results were catastrophic because DRE was written around a system where parts are constantly trying to shed heat. So turning down dissipation results in rockets that explode during launch much more frequently than they ever did before. Not good.

Hopefully stock reentry heating means this will change in 1.0. I doubt it will be all that realistic though so DRE will still have it's place in my modlist.

This brings up a thought though. Does this mean that small items attached on the shielded side of a heat-shield act as heat-sinks like they do for engine heating?

Edward

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Hopefully stock reentry heating means this will change in 1.0. I doubt it will be all that realistic though so DRE will still have it's place in my modlist.

This brings up a thought though. Does this mean that small items attached on the shielded side of a heat-shield act as heat-sinks like they do for engine heating?

Edward

They SHOULD change it in 1.0; honestly it's the first thing that should change or they're going to have trouble balancing the system. Not sure how much realism will ever enter into it though since as Nathan has pointed out, a realistic Kerbin reentry isn't nearly as deadly as one over Earth. That said though, the stock system dissipates a LOT of heat even for a default DRE Kerbin reentry. I put in code to measure incoming 'heat', and found that with the new experimental code, the shield had taken in enough to heat it by 90,000 Celsius.

Re: Attachments on shields: The short answer is yes, but the degree to which that happens depends on whether or not the shield's heatConductivity has been changed. A lot of the shields that the mod comes with (and a few 3rd party shields like SDHI are modified by DRE) to have a value of 0.01 so they're only transferring about 1% of what they take in. That can prove to be a double edged sword though since it means that shields can take in heat from external, non-reentry sources that can destroy them. That mostly seems to be an issue with parts like the Mk1 pod, which will either have that property tweaked or restored to default next update.

As far as DRE's future, post-KSP 1.0, I think it's likely to stick around, unless KSP's new reentry system mind bogglingly exceeds all possible expectations of it causing everyone to say 'holy crap, this is what we've always wanted!', or at least be extensible enough that either DRE becomes unnecessary or paves the way for a total re-write of DRE revolving around the new update. I imagine though that there will be a delay before there is even an update since I'd either have to bypass the new system or find a way to work within it.

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Back again with more beta feedback. Re-entry from a moderate 700 km orbit with the low end of your suggested settings (1, 1, 1, 1, 2.41) caused a Mk.I pod to explode fairly high in the atmosphere, with only 2 points of its shield ablated. Reducing the multiplier to 1 let it get through with a fairly reasonable-looking heating level, but still only 4 points of the 250 ablated off.

It feels like the shields just aren't ablating enough to provide useful protection or something.

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Back again with more beta feedback. Re-entry from a moderate 700 km orbit with the low end of your suggested settings (1, 1, 1, 1, 2.41) caused a Mk.I pod to explode fairly high in the atmosphere, with only 2 points of its shield ablated. Reducing the multiplier to 1 let it get through with a fairly reasonable-looking heating level, but still only 4 points of the 250 ablated off.

It feels like the shields just aren't ablating enough to provide useful protection or something.

Sounds like a problem with the ablation metric setting which isn't exposed in the mod's debug menu yet. Working on that in the next update.

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