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


Starwaster

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asmi: Huh. Are you using KJR? As you might have seen from that thread I had an issue with my 4m Mk1-2 and a 4m shield. If not...I'll check. You _do_ know that you don't need a shield for the Mk1 pod, right? It has a built-in shield. It must look awful funny with an extra shield. Or did you need a thicker shield?

I've said 1.2 pod which is stock 3-seat pod. And yes I do have KJR.

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Sorry, I interpreted that as 1.2 meter pod, not the Mk1-2 pod. Sounds like the exact same issue I'm having then--the resize is probably immaterial. ferram said he's looking into it.

Have you tried without KJR? When I tried the 4m size version without KJR, it worked (even with my gigantic S-IC of ~560 tons).

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For a shield with only 848 units of ablative shielding I used these values and it deorbited fine (peak G around 7):

Is that in reference to any of the regular DR parts? The 1.25 and integrated Mk1 pod heat shield only have 250 units of ablative in contrast to the 848 you list above.

I could get into tweaking the number of shield units as well, but so far I've been restricting myself to the max dissipation to keep things simple.

Edited by FlowerChild
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For some reason, my re-entries in the Real Solar System mod + FAR are pretty much always + 20gs, and this is only from the sub-orbital flights i did to test the mod, @ around 4000 ms. This generally means death for all kerbals involved, and sometimes the parts also exploding. Ideas?

You'll be much better off with an actual orbital reentry. Suborbital flights reenter very steeply, and at 4km/s you're pretty much dead. An orbital reentry is much more shallow and allows you to stay high for longer, safely reducing your velocity. Remember, angle matters more than speed for reentry. Low angle = more total heating but lower rate, high angle = less total heating but higher rate. Here (according to your peak Gs) you are clearly exceeding the rate at which the heatshield can ablate. Therefore, you need to reenter at a shallower angle.

Keep your apoapsis as low as you can to decrease the angle (i.e. increase your hop's range via horizontal speed, not altitude). If that's not possible, consider making a burn before reentry, retro and rad+ (up) to slow you down and "drag" the apoapsis over to your position. Also try to use lift during the reentry to keep you high for longer and keep the vertical speed low.

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FlowerChild: It's the 4m Apollo heatshield I released here (a rescaled 2.5m one, so the stats should work on the 2.5m one too): http://forum.kerbalspaceprogram.com/threads/55145-0-22-WIP-Alpha-Real-Solar-System-v5-1-HOTFIX?p=769458&viewfull=1#post769458

848 because the Apollo heatshield massed 848kg and I was going for a 1:1 clone.

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Sorry, I interpreted that as 1.2 meter pod, not the Mk1-2 pod. Sounds like the exact same issue I'm having then--the resize is probably immaterial. ferram said he's looking into it.

Have you tried without KJR? When I tried the 4m size version without KJR, it worked (even with my gigantic S-IC of ~560 tons).

Just tried that without KJR - same thing. Looks like there is something wrong with the heatshield itself.

UPDATE:

adding this:

breakingForce = 630

breakingTorque = 630

fixed the problem.

Edited by asmi
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FlowerChild: It's the 4m Apollo heatshield I released here (a rescaled 2.5m one, so the stats should work on the 2.5m one too): http://forum.kerbalspaceprogram.com/threads/55145-0-22-WIP-Alpha-Real-Solar-System-v5-1-HOTFIX?p=769458&viewfull=1#post769458

848 because the Apollo heatshield massed 848kg and I was going for a 1:1 clone.

Ah, very cool! Sorry, was confused as to whether you were giving feedback on my 1.25m tweaks or talking about something different :)

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Hmmm mod doesn't seem to do do anything for me :( no parts burn up in the atmosphere at all unfort.

go to the deadly reentry continued thread get that one. plus if a mod isnt working its normaloy not installed right

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Here you go. Be aware that they must be installed in the KSP/Parts folder, NOT GameData.

Many thanks, have those..... was hoping that maybe for Christmas SantaNathan might put some new 'toys' in our stockings......... hint.... hint.... hint....

but thanks for thinking of that and posting. Have a great day.

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asmi: cool! Will verify when I get home, and add for next release (and check the other shields).

combat squirrel: try following FlowerChild's suggestion and increasing shockwave exponent. It turns out that Kerbin just isn't that deadly if you use real life heat values on a planet 1/3 the size of the Moon.

Holmes: go to GameData/DeadlyReentry and delete custom.cfg. Presto, default values return.

drtedastro: shouldn't be hard to add DREC-compliant attributes to those heatshields, just like DREC does for HOME. I trust that legacy parts still generate confignodes that MM can modify.

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You need to add the ablative shielding RESOURCE block, and the ModuleHeatShield MODULE block, from, say, the 2.5m heatshield. You might also want to adjust the part's mass, keeping in mind that every unit of ablative shielding you add, adds a mass of 0.001 tons (so wet mass for the 0.12t shield with 1000 units of AblativeShielding will be 1.12t).

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asmi: cool! Will verify when I get home, and add for next release (and check the other shields).

I'd also suggest you to decrease crashTolerance to something much lower as right now heatshield survives free fall from 500 meters :) I've set it to 10 here, and it seems to be good enough. The only question I've got - is there Linar-return-rated heatshield as looking at my reentry experience, that default heatshield won't survive Lunar free return reentry.

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I've managed to reenter several times, using FAR and DR, with my entire rocket remaining rocket, from a Munar mission. I set periapsis to about 33 km, and aerobrake on a pass. So far so good, you can aerobrake in earth's atmosphere without a heatshield if you choose a high enough altitude to do it from.

I do a couple of passes, which makes my trajectory suborbital, and then I'm able to reenter with the entire bottom stage of my rocket still attached.

There are some flames, but apparently stock fuel tanks don't burn up at at a mere 450 C. And, DR does not seem to model the high pressure shockwaves that would tear those thin walled tanks apart.

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@asmi with the mk1 pod I made it back with a periapsis of 60km like three times.

@BrickedKeyboard are you playing with RSS? because with such a low periapsis you should definitely explode when coming from the moon in RSS

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I'm not saying DRE isn't working - it is, I've burned up many times. I'm pointing out that with good navigation you don't need a heatshield, and this is unrealstic -> on earth, there is no way at all to avoid burning up unless you can shed your orbital velocity with engine burns.

RSS? what's that? 33km is a fairly high periapsis, the atmosphere is quite thin and there are only flames briefly. You also streak past that point very quickly, 33km is the lowest point of the aerobraking pass.

The point is, after you do several braking passes, your orbit becomes briefly circular and then your apoapsis drops below the periapsis and you are going to reeenter for sure now. DR does not think there is enough energy, coming in from a low circular orbit, to burn up.

I disagree, there almost certainly is, and I think that either the effects of reentry are being understated or the stock parts (goo tanks, stock engines, stock fuel tanks, etc) are too resilient.

Of course, another factor working in the other direction is that high mach aircraft can fly so fast they have flames around them. They just barely survive, heating up to 900+ C in the upper atmosphere. Much harsher and they will burn up as well -> it isn't possible to heat shield their parts, and the real SR-71 doesn't burn up.

Edited by BrickedKeyboard
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