Re-entering Kerbin steeply at 3300m/s. Is it possible?

[iiLuJ]

Hello,

I'm currently stuck on an autosave after a trip to Minimus where i'm re-entering Kerbin quite steeply at 3300m/s and I am just unable to do it... I have a heat shield ant it seems to hold up, but my mistery goo and electrical batteries always explode ruining everything. I would like to ask is it even possible to re-enter.

This the picture of the craft. Speed, altitude and the craft itself is visible in the picture below :

https://prnt.sc/S2aat8NN3VnI

[James Kerman]

Welcome to the forum @iiLuJ, your question has been moved from KSP discussion to here, a great place to ask gameplay questions.

It looks like you are essentially de-orbiting straight down so one thing you could try is spinning the vessel on the way down by pressing and holding either 'q' or 'e' when you see the heat effects on your mystery goo and batteries. It also looks like you have an inexperienced pilot on board without the ability to hold retrograde () so you need to try to keep that marker in the centre of the navball.

Edited April 26, 2022 by James Kerman
spelling

[Admiral Fluffy]

You could also collect the science from the Goo, and get it in the command pod.

Welcome to the forums @iiLuJ!

[king of nowhere]

can you survive at 3300, in general? sure, my record is close to 10 km/s.

Can you survive with that ship? Surely, it's got a thermal shield.

Can yo survive with that shield and a steep reentry? Hard to say. Probably you can save the pilot.

But the goo and batteries? forget about them. you could forget about them in a normal reentry too. goo and batteries are exposed on the outside. the goo has high thermal vulnerability, it explodes before other stuff. that one cannot survive unless shielded. the batteries have average thermal ratings, but in that position, exposed to full airflow during a brutal reentry? not a chance.

Just be glad you can save the pilot. losing a couple parts during reentry is only a minor cost anyway. and next time, learn to make better reentry trajectories. if you want to save delicate parts, set a periapsis at 55 km and aerobrake gradually over many passages

[Snark]

1 hour ago, iiLuJ said:

I'm currently stuck on an autosave after a trip to Minimus where i'm re-entering Kerbin quite steeply at 3300m/s and I am just unable to do it... I have a heat shield ant it seems to hold up, but my mistery goo and electrical batteries always explode ruining everything. I would like to ask is it even possible to re-enter.

In general, yes, it's possible, for a ship that's designed in a way that can take it.

That ship, however, is probably doomed. 

Problems here:

1. Unprotected parts.  The mystery goo and Z-400 batteries are sticking off the side of the ship and are not behind the heat shield.  It's not going to protect them, they're going to be exposed to the oncoming airstream, and they'll quickly be toast.
2. Vulnerable part in direct contact with heat shield:  I'm not sure what that part is right behind the heat shield, but I'm guessing it may be a Science Jr. materials bay, perhaps reskinned from some mod?  If so, then there's a good chance it may be a goner, too (though not a foregone conclusion).  That part has a max temp of only 1200 K, and a heat shield during reentry can get substantially hotter than that.  It miiiiight be OK on a fast steep reentry (ironically enough), if the heat shield doesn't have time to raise its internal temperature up too high.  But it'll be dicey.
3. Aerodynamically unstable.  It looks to me as though your CoM (center of mass) is probably way too high, i.e. up by that heavy dense pod, and not down by the heat shield.  (Because you've got that big, fluffy, low-mass part under the pod).  This means that, aerodynamically speaking, that ship is really going to want to flip around and point nose-first, which would cause you problems even if the above-listed ones weren't an issue.  The only thing you have available to stop you from flipping is your SAS... and even if you had the hold functionality available (which it looks like you don't), you're going to be pulling so many gees on that steep reentry that probably nothing can stop it from flipping.

So, yeah, unfortunately you're probably toast.     About the only way I could see that you could pull this one out of the hole would be if you've got an engineer aboard there who can go EVA, disassemblethe ship, discard all the extraneous science gear, re-attach the heat shield directly to the pod, and then re-enter that way.  That, I expect, would work fine.

For future reference, ways to avoid this sort of problem happening again:

• Keep everything behind the heat shield.  Any part that sticks out from behind it, like the mystery goo and Z-400 batteries here, is gonna have problems.  For example, in this case, if you wanted to keep those parts safe, you could have mounted them up on the sloping sides of the command pod, where the command pod's wide bottom end would keep them safely in its lee.
• Don't attach anything with a low melting point directly to a heat shield.  For example, a materials bay is only 1200 K, which is really low.  You can mitigate this by attaching some part with a decent temperature tolerance (for example, a Z-1000 battery) between the heat shield and the melty part.
• Make sure that your CoM is close to the heat shield so that it will be aerodynamically stable during reentry.  Don't put big, lightweight parts where they'd need to be in the front of the ship (i.e. at the heat shield end) during reentry.

By far the simplest, sturdiest, toughest design for reentry is a conical command pod (like the Mk1, Mk1-2, or similar) that has a heat shield attached directly to the pod.  That's an incredibly tough design, is rock-solid stable during reentry, and can handle very fast, steep entries with no problem.

I'm sorry I couldn't be the bearer of better news, here.

 

[Vanamonde]

If you have the Kerbal collect the science into the pod and pre-activate the chutes before you lose the batteries, it might not matter if those othre parts explode. 

[Snark]

34 minutes ago, Vanamonde said:

If you have the Kerbal collect the science into the pod and pre-activate the chutes before you lose the batteries, it might not matter if those othre parts explode. 

+1 to this advice, in general (and absolutely, try this to see if it helps!)

In the current case, though, the (probable) aerodynamic instability, and/or that materials bay (if that's what it is) exploding so that the heat shield is no longer attached to the pod, seems to me likely to spell doom.

[Vanamonde]

2 hours ago, Snark said:

+1 to this advice, in general (and absolutely, try this to see if it helps!)

In the current case, though, the (probable) aerodynamic instability, and/or that materials bay (if that's what it is) exploding so that the heat shield is no longer attached to the pod, seems to me likely to spell doom.

I have had situations where an intervening part went kablooey and wind resistance pushed the heat shield against the remaining portion of the craft so that it served its purpose anyway, finally falling off after the chutes opened.

[DeadJohn]

As others have said, parts of that craft, maybe all of it, will overheat during your steep reentry.

If you absolutely need to save 100% of the ship, options are to use the alt-f12 cheat menu to turn off heat damage, or use a mod to teleport the ship to the ground. "Cheating" is okay if it makes the game more fun for you.

[dci]

If there is problem with lack of EC after heat destroys batteries, you can try transfer EC to command pod before reentry, there is 50 EC capacity. This should be enough to keep it retrograde during descent. And, ofc, move experiment results into command pod to protect them. You should be okay, ship looks survivable.

[Ande]

 I just got into the habit of using an experiment storage on the nose of the craft clipped down so it's just peaking out the top. Then I place the parachutes on its side and a jnr docking port on top. (Altho obviously this could be the simple cone parachute if you wanted).

When I do science missions I can just then run all experiments and then select the experiment storage and say "collect all"... The storage being at the top keeps all that sweet science is then safe and sound.

 I just got into the habit of using an experiment storage on the nose of the craft clipped down so it's just peaking out the top. Then I place the parachutes on its side and a jnr docking port on top. (Altho obviously this could be the simple cone parachute if you wanted).

When I do science missions I can just then run all experiments and then select the experiment storage and say "collect all"... The storage being at the top keeps all that sweet science is then safe and sound.