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No ablator but im ok... why?


Solar71
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Hey guys.

Quick question about ablator.

So Im reentering Kerbin atmosphere at about 2,300 m/s.

Mk1 + 200 ablator heat shield.

Im playing with reentry heat at a 3.0 multiplier, for more challenge.

So I tried reentry 3-4 different ways without a heat shield and blew up every time... That's a good thing.

So now I MUST use a heat shield.

Ok so Im reentering and the temperature is going up on my heat shield...

Ablator starts going away... 199/200

As I get lower, the temp goes WAY UP!!! ablator at 93/200

Little bit lower (about 19,000m) and now ablator is at 0/200

But my heat shield does not blow up... and actually starts cooling off even though external temp says 6,500 kelvin.

So where is all the heat going?

My MK1 stayed at about 406 kelvin.

No ablator left, so what Is acting as the heat sink?

Sorry if this is a silly question, I just want to understand the mechanics. If ablator is completely gone, then where is all that heat going?

Thanks :)

Edited by Solar71
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The heat is probably being carried away by convection. Can't more than guess without trying it myself or seeing screenshots.

There is a point in any reentry where you simply have slowed down enough that you're no longer heating up. Maybe you just happened to randomly hit things exactly so that at the moment you run out of ablator, you've slowed down juuuust enough for things to be okay?

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If you had lost all ablator by 25km then you likely would have been toast. Craft lose heat from radiation and in atmosphere also from convection. You can watch the process yourself by right-clicking a part, after you turn on the thermal details in the action menu using Alt-F12 -> physics -> temperature -> action menu.

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If you had lost all ablator by 25km then you likely would have been toast. Craft lose heat from radiation and in atmosphere also from convection. You can watch the process yourself by right-clicking a part, after you turn on the thermal details in the action menu using Alt-F12 -> physics -> temperature -> action menu.

I see what you're saying. ok so basically its working correctly?

After ablator is gone the ship should still be able to stay cool and the heat shield should get cool and cooler without ablator?

As long as the ablator hits zero below 25k but not above it?

Ok thanks, I didn't know this.

Much appreciated. :)

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Well 25km was just a guess as it generally depends on your speed and heat characteristics. After it loses all ablator the heatshield is just another part, but by that point you were going slow enough that a normal part with that thermal mass and heat tolerance would survive just fine. Basically, you were lucky... this time. However, if you can find ways to increase your drag, you don't even really need a heatshield at all for Kerbin re-entry from something like Mun or Minmus.

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I recently re-entered the atmosphere with no heat shields going 6.3km/s. All I lost were a couple solar panels.

It was terrifying, but very anti-climactic. I have decided it is completely unnecessary - at least at Kerbin - to EVER use a heat shield.

Here's hoping 1.0.3 will reintroduce that need.

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I recently re-entered the atmosphere with no heat shields going 6.3km/s. All I lost were a couple solar panels.

It was terrifying, but very anti-climactic. I have decided it is completely unnecessary - at least at Kerbin - to EVER use a heat shield.

Here's hoping 1.0.3 will reintroduce that need.

That would be very nice.

TBH I personally "feel" like KSP is just fudging heat all together.

When my ablator was at 0/200, It was still showing me that the external temperature was about 6,500 kelvin, "THATS HOT"

I understand what cybersol is saying, but it just doesn't "feel" right.

Lets say I have a heat shield with 200 ablator, then after getting really hot the ablator eventually goes to zero.

Ok so now, there is only what left? A supporting structure for the ablator? what's under the ablator? I would guess some sort of metallic

support, but possible ceramic?

Either way that material would get hot as well...

It honestly seems to me, that the ablator is just something to "trick" KSP players into thinking heat is real.

Honestly, it "feels" like smoke and mirrors to me.

But of course I could be completely wrong. I would love it, if a Squad Dev person would chime in with something.

- - - Updated - - -

One more thing. Im going to turn up the reentry heat multiplier to 10.0 and see if something happens to my heat shield after ablator is gone. Just as an experiment...

This should let me know if heat is even real in ksp. haha

lol wish me luck.

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I hear say that stock Jool atmosphere is pretty burning and I know first hand that Eve's one can and will overheat and burn your ship if you are not careful enough.

Kerbin is not the harsher place where that stuff might be used and they should be tested in the harsher possible situations before being so questioned.

Podless Kerbals surviving orbit reentry and landing on their own are pretty fun though.

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I have a feeling that your PE is waaayy too low. For lko a PE of 50 should be plenty to deorbit you, while coming back from the mun I aim for 35 km and I aim for 30 for minmus. For interplanetary I have always aimed for 10km.

For any reentry from the kerbin system lose a tiny bit of ablator, while any interplanetary rentry I lose most of my ablator but that's most likely because of my steep decent path and me going 2-4 km/s faster than kerbin reentry

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