How much did they change heat? (6 months)

[MrOsterman]

So I've been away for about 6 months.  With summer break I came back to restart a career mode on Normal Difficulty.  I'm really struggling with reentry now for some reason.  

Here's what I sent on a trip around the mun:  going from top to bottom:

1. MK1 Parachute
2. 2 round batteries
3. MK1 Command Capsule
4. Science Jr.
5. Inline Reaction Wheel (the MK1 sized one)
6. Bay with additional Science
7. Heat Shield.

I've tried two different reentry profiles:

1) Straight return from the mun set to a Per of 22k - Burned up on reentry.

2)  Return from mun setting a decelerating orbit so that my AP for the orbit was 100k, Per was 36 - Burned up on Re-entry

I had a feeling that the direct "figure 8" of out to the moon and back was going to be problematic for speed (that's a long fall back to Kerbin to hit the atmosphere).  I even tried burning as much "spare fuel" as I could at about 70k of altitude just to break.  My last effort on reentry I was only going 2k m/s when I hit the atmosphere and sure enough, burned up and exploded.

And this isn't even counting the multiple times I made some small misstep on the re-entry pathway, leaned the ship too much to one side or the other, and BOOM that was that.

Did they radically change things or something because I don't remember getting back to Kerbin being THIS difficult.  I'm not even sure i can stomach more complicated missions if at the end of it I can't get anyone home....

 

[ElWanderer]

If you hit F3 to bring up the log, which part is exploding first?

Are the doors of the science junior open? Duringthe v1.1 pre-release, I remember a lot of people reporting that the science junior doors would stick out beyond the protection of the heat shield and overheat. I'm not sure of the status of that now.

Are you able to maintain a heat shield first orientation? That set-up sounds like it may want to flip and fly capsule first once in the atmosphere.

Lastly, if the atmosphere seems to act really weirdly, it may be that your physics.cfg file is out of whack and needs regenerating (Steam validate local files? Delete and let the game recreate on start-up?)

[MrOsterman]

I'll look again with another effort (and some tweaks because having a pilot die on re-entry is starting to just burn me out too much.

What I do know without testing again and looking for it is that my parachute burns up while it's stowed so part of me is wondering if the ship I'm bring in is just too tall for re-entry as it is and I'm seeing the effects of ~wrap around~ heat and fire.

I'm also coming in butt first the entire way.  But it does seem really really sensitive to the slightest twitch and boom. I don't ever remember re-entry being this ~tense~.  I know it's supposed to be and all but.....

 

[kBob]

If I'm out of propellant to retro burn I usually try for a Pe in the low 30's.  But the Mk1 is just not the greatest for heat.  Try putting a service bay as the bottom most part that's returning with maybe a heat shield with about 2/3 of the ablator removed (especially if you aren't planning on having much propellant on the reentry): those service bays are really tough (and open the doors before reentry to get the drag).  Also I usually, if I'm low on propellant, do my retro burn starting around 100km since I find it's better to ditch the extra weight sooner (but you don't want to do it too soon and screw up your re-entry trajectory).  And yes I swear each time I restart a career the heat simulation has been made worse, but I think maybe part of it is just getting spoiled by MkII and higher parts: it makes it seem harder when you go back those early parts .

[Aegolius13]

I've noticed something similar when trying to land or aerobrake with less than ideal craft.  If I can hold retrograde, the bottom of the stack (e.g. engines and fuel tank) get hot but hang in there.  But if the thing tips over, everything blows up almost instantly.  Not just the fragile science instruments and solar panels, but even the Mk 1 capsule, which is supposed to have good heat tolerance.  

No clue why.  I would expect the ship to heat up more after doing more of a pancake, but not that much quicker.

 

[bewing]

If you set your Pe to 61km, you can do as many aerobraking passes as you need to before reentry. (Yes, I know that every second of gameplay time is precious to some people -- but physics and engineering have their limits.)

Squad keeps a small reentry window for direct landings from the Mun, but that is at a Pe of 30km to 35km, and it only applies to a MK1 command pod + parachute + heatshield.

It's not heating that changed -- the MK1 parts have had their drags reduced by 25%. So you don't slow down, and you hit the nasty parts of the atmosphere going 200 m/s faster.

Add some aerodynamics! Two pairs of tailfins at the top of the craft (set to opposite Deploy modes) will turn a reentry nightmare into a cakewalk. But then you need a shallow reentry to allow the aerodynamics time to do its work.

[MrOsterman]

36 minutes ago, bewing said:

It's not heating that changed -- the MK1 parts have had their drags reduced by 25%. So you don't slow down, and you hit the nasty parts of the atmosphere going 200 m/s faster.

 

Okay now THAT makes a little more sense to what I'm seeing.  I was starting to wonder what was up but it makes sense that they sleekified the MK1 parts which would make them slow less and thus create a tighter re-entry window.

Of course that also means I need to rethink some of my planned science missions until I get bigger command pods or to be a little less optimisitic in what I plan to take with me.

[Violent Jeb]

that command pod combined with the science jr is a huge amount of mass, low heat tolerance, and very low drag. 

Result, you come flying in wayy too hot.

Edit: squad did change the atmosphere, and reduced the drag on the mk1 parts quite a bit.

What I would suggest is to have your kerbal get out in orbit (or suborbit), take the data from the science jr, and everything from the science bay, then jettison both of these along with your empty tank and engine

You will save probably 40-60% of your total mass. Now the heat shield+command pod combo should be able to come in with almost any angle with 3km/s velocity, and you can open your chutes once you're subsonic.

Almost always, its the science jr overheating and causing catastrophic failure between the rest of the craft.

Edited June 27, 2016 by Violent Jeb