Heatshields are broken for me

[Clockwork13]

Maybe I'm just overreacting, but I'm pretty convinced that heatshields for me are broken. I feel like when I'm landing at my last stage, the ship acts as if my heatshield weren't there. I'm aiming perfectly retrograde, nothing on the side of my capsule, and a heatshield below it. Somehow my capsule ends up blowing up every time before I can reach the surface. I tried once using a whole stage of my ship as a heatshield, but then it flips over.

EDIT: didn't realize this was wrong subforum. Someone please move it

Edited September 23, 2015 by Clockwork13

[mrclucks]

How steep are you trying to reenter? For kerbin 35k periapsis is low enough from about the mun, a 40k or so periapsis from minmus will slow you down enough and then you can change your periapsis down to 35k to get down.

I always check my center of mass for my return vehicle so most of the mass is at the bottom/heat shield side. You can also put fins on the opposite side of of your heat shield so aerodynamics help you not burn up

[The_Rocketeer]

The thing is, re-entry now has a 'sweet spot'.

Come in too shallow and you spend too long at too high a temperature and burn off all your ablator, which = boom.

(Note: I've never done this myself, there was a thread about it happening in RSS, but the principles are the same).

Come in too steep and you generate so much friction it overwhelms the ablator, which = boom.

You have to enter the atmosphere so that you slow down and descend just right to reach the lower atmosphere (below 20km) slow enough to not explode from heating (guestimate ~1700m/s depending on drag). You definitely want to be under ~1200m/s by the time you get to 10km or you'll just pop like a popcorn kernel.

[Foxster]

I must be doing something wrong then because I have never used a heatshield and every craft gets down OK.

[The_Rocketeer]

I must be doing something wrong then because I have never used a heatshield and every craft gets down OK.

Well, heatshields aren't strictly necessary for Kerbin, but it does depend a lot on your re-entry angle/apoapsis altitute/re-entry velocity. There is an upper limit (on all/any of these) that's doable without either 'skipping' back into space or exploding due to overheating. Having a heat shield slightly increases that limit, but that's not an excuse for dropping vertically from Minmus' orbit.

[Cairol]

I use them always because I like the realism factor, and it also makes the re-entry more forgiving overall.

Difficulty is, to not overload them thermally.

[mikegarrison]

I use them always because I like the realism factor, and it also makes the re-entry more forgiving overall.

Difficulty is, to not overload them thermally.

Yeah, the heatshields have an annoying tendency to get hot and blow up, taking the rest of your ship with them. As if getting hot wasn't the whole intended purpose of the heat shield?!

[Slam_Jones]

Personally, I've avoided a lot of the stress of dealing with it by setting re-entry heat to 0%.

It's not really a game mechanic I enjoy.

[wumpus]

Odd, I've never experienced this (presumably from trying to keep the acceleration meter at sane levels in previous versions).

My claim is that airbrakes are overpowered. Try placing some airbrakes on your capsule and seeing if you still have the problem (seriously, I expect that just using a perigee of ~30,000m will work better. Possibly with some higher passes if you are using aerocapture from a different planet).

[SpeedDaemon]

Also remember that with the post-1.0 aero model, you can use the re-entry vehicle as a lifting body to correct somewhat for too-steep or too-shallow re-entries by pitching in the direction you want to go.

[xebx]

I use heatshields mainly for Eve entry, Kerbin is ok with 40km Pe.

The Eve-Kerbin return module (7 kerbals + science service bay) i'm using have an heatshield but with 100 ablator only, and it's nearly useless because the interplanetary booster have enough fuel to slow down to safe velocity.

If you experience capsule explosion with different entry angles and decent velocities, try setting aero heating production to 99%, i have the feeling it reduces the weird/fast thermal skin effect that happens sometimes.

Oh and fully fuelled / heavy ship will generate more heat, better burning the fuel to slow down than exploding.

Edited September 23, 2015 by xebx

[MarvinKitFox]

Yeah, the heatshields have an annoying tendency to get hot and blow up, taking the rest of your ship with them. As if getting hot wasn't the whole intended purpose of the heat shield?!

Actually, the *whole purpose* of the heat shield is to stay cool, by dumping most of the re-entry heat into the bit of the heatshield that ablates off.

Obviously this process has a certain maximum rate, and if you force heat in faster than the surface can slough it off, you are making a bomb.

[Clockwork13]

Thanks for the info. After atleast 20 tries, I successfully came up with the idea sacrificing my second to last stage with magnetometer booms that were attached to my ship to slow down my descent enough where i was able to decouple my pod and not get blown up.

- - - Updated - - -

And it was going well until the game crashed. RIP jeb

[The_Rocketeer]

And it was going well until the game crashed. RIP jeb

Sad.

But it doesn't seem like this should be necessary. Can you upload some pictures of what's happening to your re-entry craft? That might explain a lot.

[xebx]

Maybe it's due to mod interaction ?

[Thegamer211]

I got non heatshielded crafts from mun orbit with pretty steep re-entries. (does the engine count as an heatshield?)

You should check the debug thing to see if theres some error.

What mods do you use?

[sal_vager]

You might be suffering from a bug Clockwork13, it's possible for KSP to load with the wrong values for physics, normally the Physics.cfg and the game will match up so if the Physics.cfg is deleted it is reset using the values in the code.

But they aren't correct, so you mustn't delete Physics.cfg with KSP 1.0.4, if you did then you can get the file from here.

Also, KSP will use the incorrect internal values if it can't find the Physics.cfg, this can happen if you made a shortcut to the KSP.exe on your desktop, KSP will look on your desktop for Physics.cfg, not find it and your heatshields will be broken.

So try that file, and try starting KSP by using the KSP.exe directly.

Edited September 25, 2015 by sal_vager

[legoclone09]

Sal, you forgot a bracket in your post.

[sal_vager]

Sal, you forgot a bracket in your post.

Fixenated!