DJK

So.. since at the moment command pods manage heat more efficiently than heat shields (they hit lower peak temperatures & it takes longer for them to heat up to said temperatures) and since there are some people around that want a more challenging re-entry & a real purpose for heat shields, but never fiddled with the physics values, i figured this might help. After tweaking some stuff.. i managed to make re-entry a bit more of a challenge. Following the settings below, a single command pod (without heat shield) will be able to re-enter from LKO using a proper re-entry trajectory - but just barely. Do it wrong and your kerbals will be pretty much toasted. Heat shields work roughly as in default 1.0.2 - meaning that a LKO re-entry will use up ~1/3 of the ablator. Doing a Mun re-entry will use up ~2/3 of the ablator - again, this depends on your re-entry trajectory. With the following settings, my SSTO tests did not burn up during ascent or re-entry. They do heat up pretty good though, but that is to be expected since there is no dedicated heat shielding for space planes. I should also mention that parts with low maximum temperature will be glowing red hot (and possibly explode) during ascent if you go too fast in the lower atmosphere. No problem if you follow a proper gravity turn with a sensible speed to altitude ratio. Disclaimer: Everything i did was by my own initiative & to suit my own liking & designs. All tests were done using 120% re-entry setting & generic ship designs - nothing fancy. These settings might not work for you, but at least give you some insight of how to tweak re-entry thermal effects. I take no responsibility of whatever happens during tweaking and/or using these settings. Now, what i did was the following: 1. Set re-entry thermal effects in the options to 120% 2. In the "Physics.cfg" file, located in the main "...\Kerbal Space Program" directory, i changed the "convectionVelocityExponent" value from 3 to 3.35 - Note that this number is extremely sensitive. This basically means that the more speed you have during atmospheric re-entry, the more heat is transferred to the ship by convection. 3. At this point the default heat shields are extremely useless, so i had to balance them out. To do so, i changed the "hsp" value of the ablator resource definition from 100 to 1000. The resource file is located in "...\Kerbal Space Program\GameData\Squad\Resources" directory and it is named "ResourcesGeneric.cfg" Aaaand thats about it. Feel free to expand or correct anything if needed. And ff you do decide to apply these changes, make sure you backup the files and quicksave before doing any changes. Let me know how it works for you if you've tried. Cheers, DJK

I believe this is the intended behavior for 1.0.2 - and the most realistic one, in my opinion. Even though i never had any issues with pods slamming into the ground during proper re-entries, i understand your point. Note that you can change the deployment altitude in the VAB/SPH by right clicking on the chute, or by setting the "deployAltitude" value in the part .cfg file to whatever you deem to be necessary.

No problem. Let me know if you can reach a sensible configuration regarding re-entry.. if you decide to fiddle with the settings. EDIT: I've tweaked some settings here & there and came up with a more challenging re-entry - at least for my taste. Please see: http://forum.kerbalspaceprogram.com/threads/118775-Tweaks-for-a-challenging-re-entry-effect

There must be wrong with your ascent profile / speed.. because i'm using 120% re-entry heating and with an 80-100 convection factor set by debug (for testing purposes atm, default with 120% thermal setting the convection factor is 40) and i still don't have any issues with overheating during launch. Fins start overheating sometimes, but nothing explodes. Note that i don't use mechjeb. The gravity turn is initiated by pilot below 1000 m altitude, and after that the rocket continues its turn by its own.

re-entry heating is currently a joke.. you don't even need heat shields to re-enter kerbin.. more so with the 1.0.2 update.. the pod itself (without a heat shield) heats slower & peaks at a lower temperature than the heat shield. Thats with 120% re-entry heating. I did however managed to reach a resonable re-entry effect previously in 1.0, but 1.0.2 made sure to change that EDIT: You might want to check this for tweaking the thermal effects: http://forum.kerbalspaceprogram.com/threads/117930-Guide-New-temperature-rules-for-parts-in-1-0-%281-0-1-updates%29

ok, just tested the and it does indeed work.Same for: Probably gonna mess around with the values and see if i can come up with a "fix".

Thats basically because some parts have more thermal mass than others.. in my tests for example, the mk1-2 pod has enough thermal mass to keep the shield nearly below ablation temperature. Also, that heatConductivity line on the mainsail might be useful, but i'm under the impression that there are more variables that needs tweaking (to which there is no access thermalMassModifier in the parts .cfg file).. like thermal mass calculation. Because lowering conductivity yields no heat transfer between parts with very low thermal mass, while working ok for higher thermal mass parts. In any case, thats a good find, ty for sharing.

I have not fiddled with those two options yet.. but i'm assuming its something related to the sun's radiation and / or light levels (for solar panels)? Just a wild guess.. But i did fiddle with conductivity flux & others.. there is no point in trying.. at least for me, tweaking them fixes something but makes something else worse.

I've heard alot of people complaining about blowing up.. but truthfully.. i re-entered with both mk1-2 and mk1 coming from mun with 25k Pe @ kerbin.. perfectly safe, with or without shields. 100x20 again, perfectly safe.. sub-orbital perfectly safe. If i put heat shields on mk1-2 and do an 100x20 re-entry it ablates nothing.. 0.. or maybe 1 unit at max. I also did a fresh install of the game when 1.0 came out and currently have no mods, except engineer, hyper edit (to make the tests easier) and visuals. Nothing to interfere with the aero/thermal system. The only way i could heat up the mk1-2 pod + heat shield was coming down from Mun at a 90 deg. angle relative to kerbin's surface.. basically falling out of the sky.. and even then nothing blew up.. the pod just smashed into the ground at 1800 m/s. Heat shield did heat up to 2000 deg. and ablated roughly 50% though.

Indeed conductivity is at fault here.. or so i've concluded while playing around with the new thermal options in debug menu. Or better yet, the way conductivity is handled. Lowering the conductivity flux worked fine for mk1-2 pod + heat shield (high thermal mass). The shield heated up and ablated properly.. but at the same time, with the same conductivity value, the mk1 pod + heat shield (low thermal mass) wasn't working properly anymore. The heat shield was indeed heating & ablating, as in previous tests, but there was absolutely no heat transfer from the shield to the pod. Apart from that, i am assuming that conductivity flux regulates all heat transfers, so it is pointless to tweak it.. that would render the Nerv engine, mining drill & space planes pretty much useless. At this point i'm pretty baffled of what is going on with re-entry heating.. but i'm sure that its not properly balanced.. specially for a maxed out difficulty setting. I actually want to have stuff blow up during re-entry rather than doing ridiculous re-entries with no heat shields and no worries.. that kinda defeats the purpose of having a thermal re-entry effect I hope Squad takes notice of this and at least tries to fix it somehow.. EDIT: Also, heat shields ablate from the sun while in space.. which to my knowledge is impossible (i might be totally wrong though) and when they reach 0 ablator they stop transfering heat to the other parts, if said parts are shielded from the sun by the actual heat shield.

The problem i see is not with the shields.. I understand that they need a certain temperature & air flow to start ablating, so to speak. The problem is that the Mk1-2 pod is extremely heat resistant, due to its high thermal mass, making heat shields useless in your day-to-day kerbal re-entries. Also note that every test i did was with the re-entry heating slider set to maximum - 120% The 2.5m heat shield does not ablate because the pod soaks up all the heat.. acting like a huge heatsink. Thats not necessarily a bad thing for some people.. but for those that lean towards a more.. "real" gameplay, its not fun at all. And from my understanding, that is why there is a slider, to adjust the re-entry heat difficulty to suit your gameplay, but that is quite underwhelming at the moment due to the fact that some parts aren't quite balanced (personal opinion). I'm not expecting this to be a 100% accurate representation of what happens in real life, but then again, not too far either, specially when we have difficulty options.

Oook.. just did a re-entry coming from Mun with 25km Pe. Mk1-2 pod + chute. No heat shield. 120% re-entry heating. Was perfectly fine. Peak temperature @ 1700 deg.

The solar panels and batteries explode because their maximum temperature is 1200 deg. Can do so even if they are completely shielded by the heat shield, due to heat transfer between parts. Your best bet is to use the service bays, like others suggested or use a different re-entry trajectory.

Indeed. But at 120% re-entry heating, the mk1 & airplane was heating up as expected (can do a mk1 pod sub-orbital re-entry without heat shield, but very close to the limit - seems resonable), while the mk1-2 setup i tested was child's play even without a heat shield. And while i expected to be easy to re-enter from a sub-orbital trajectory, Mk1-2 @ 1300 deg without a heat shield is nowhere near a dangerous re-entry. I'm going to try that as well, but i'm affraid that with some easy "aerobraking" that would turn out the same.. My point was exactly that some parts might need a balance pass regarding re-entry heating for maximum difficulty settings.

Ok, so, seeing that the default setting for re-entry heating is quite forgiving for someone with a decent amount of hours into this game, i decided to set the slider for re-entry heating to 120% and see how it works. I took a basic rocket with a mk1 pod with chute & decoupler to a sub-orbital trajectory with Ap @ 100km. Note that my usual sub-orbital trajectory has the Pe around 25km in atmosphere, so that the circularization burn takes < 100 m/s dV. Now, i did this flight only to see the re-entry heating so i did not circularize. On my way down, all fine & dandy, the shield ablated roughly 50% of the ablative coating. Next, i took the same rocket - but this time without a heat shield. Roughly the same trajectory.. give or take. To my surprise i could re-enter even without the heat shield. Given the fact that it was just a sub-orbital flight, thats fine for me, since the temperature values were extremely close to the point where things blow up. 3rd rocket.. same design, but with 2.5 parts. Mk1-2 pod, chute & heat shield. Same trajectory.. In this case, the max temperature on the parts reached ~600 deg, which translates to about 300 deg. celsius.. which seems extremely low for a re-entry. Even a sub-orbital one. On top of that, the heat shield ablated just 1.5 of its ablative coating. 12 units out of 800. That feels a bit underwhelming in terms of re-entry danger. Even feels a bit like cheating. EDIT #1: Just did another test run with the Mk1-2 pod + chute but without heat shield. Pod temperature peaked @ 1300 deg. - seems extremely effective :-/ EDIT #2: Re-entry coming from Mun with 25km Pe. Mk1-2 pod + chute. No heat shield. 120% re-entry heating. Was perfectly fine. Peak temperature @ 1700 deg. Definitely some part tweaking is order in my opinion. 5th run was with an airplane, which started blowing up @ 600-700 m/s - but i admit, i wasn't trying too much either. Also, i understand it is normal since the aircraft stays in atmosphere for a longer time. Given those test runs, it appears that some parts kinda need a balance pass regarding re-entry heating and how they handle it. It seems that heat transfer and thermal mass has a strong effect on how much parts heat up during re-entry (and i'm referring to the 2.5m parts). Anyone else noticed these behaviours or is it just me imagining / doing something wrong? Cheers, DJK

Or you could just turn off SAS and trim the plane manually (which BTW, works as in rl - without a FBW augmentation system). Note that IF you designed a proper plane, IT WILL be inherently stable during flight without SAS, unless you're going for an unstable design like some of the rl fighter jets use - which obviously isn't the design to be looking for when going to space, but a nice one to pull 20 G turns for fun in the atmosphere

Sorry about the screw-up, post is fixed, let me know if you can view the image https://www.dropbox.com/s/ayomiv2uaxq3wj3/reentry.png?dl=0

For anyone that has issues with reentry.. maybe this pic will help you understand.. the capsule wants to do the following: https://www.dropbox.com/s/ayomiv2uaxq3wj3/reentry.png?dl=0 Just like Apollo did.. now, ofc if you are piling up stuff on top, that MAY not going to work very well. Apart from that, i admit, the shield having no mass does make it a bit awkward. But the capsule itself (same as in that picture) is extremely stable during reentry in that position.

Mk1 pod + heat shield was perfectly stable for me once it hit the higher air densities. Required a bit of input during the first 15km, but after that it was as stable as it gets. Even tried to purposely flip it over and couldn't.

Time to show the website some F5s

399 to 402 in one refresh.. THE HYPE!

We did, yes.

Have some moar hype..