PSA: Eve (re)entry is impossible - CONFIRMED.

[Xyphos]

(Re)Entry of Eve's atmosphere is now impossible due to the recent changes in v1.0.5
Credit goes to Makki for pointing this out, but I'm just providing evidence to back up his claims.


[video=youtube_share;uU3hPkNbeCc]http://youtu.be/uU3hPkNbeCc[/video]

[Gaarst]

The fact you cannot reenter with this ship does not mean that Eve reentry is impossible.
The fact you could reenter with [I]any[/I] ship would mean that Eve reentry is [I]not[/I] impossible, on the other side.
Just a logic detail leading to a hasty conclusion.

Give me (or anyone else) time to set up a reentring craft for Eve, and you'll be proven wrong. Edited November 18, 2015 by Gaarst

[legoclone09]

What about a 3.75m heatshield, probe core, and batteries?

[Xyphos]

[quote name='Gaarst']Give me (or anyone else) time to set up a reentring craft for Eve, and you'll be proven wrong.[/QUOTE]

Please, by all means, do so.
I'd like to laugh at my own folly.

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[quote name='legoclone09']What about a 3.75m heatshield, probe core, and batteries?[/QUOTE]
Hadn't tried it, but I expect more drag and more heat and faster burn up

[surge]

[QUOTE]reentry[/QUOTE]... so you've been in eve's atmosphere, possibly started from it's ground and returned?

[ferram4]

Your test was fundamentally flawed, and even with stock aerodynamics and stock heating that very vehicle is capable of surviving reentry and smacking into Eve's surface. Starting from a 100 km orbit, dropping periapsis to 7 km (expending 100 m/s of dV retrograde), your vehicle ends up like this:

[IMG]http://i.imgur.com/WkYtoc8.png[/IMG]

Your reentry periapsis was simply too high and didn't bleed off enough speed. The problem is your procedure, not Eve. I'll also note that since I left the RCS off besides for initial orientation, I likely had more mass than you during the entire reentry, so I should have had more heating. Edited November 18, 2015 by ferram4

[cyberpawn]

hmm? try reentry with 0 pe

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[quote name='ferram4']Your test was fundamentally flawed, and even with stock aerodynamics and stock heating that very vehicle is capable of surviving reentry and smacking into Eve's surface. Starting from a 100 km orbit, dropping periapsis to 7 km (expending 100 m/s of dV retrograde), your vehicle ends up like this:

[URL]http://i.imgur.com/WkYtoc8.png[/URL]

Your reentry periapsis was simply too high and didn't bleed off enough speed. The problem is your procedure, not Eve. I'll also note that since I left the RCS off besides for initial orientation, I likely had more mass than you during the entire reentry, so I should have had more heating.[/QUOTE]

well said xD

[GoSlash27]

Xyphos,
Try it with a decoupler between the first and second ablator. It's exploding immediately when the material is gone and taking out the rest of the ship.
Best,
-Slashy

[Gaarst]

Kudos to Ferram for a simple yet efficient demonstration.
Still, if no one has done it then, I will try direct aerocapture from a Kerbin-Eve transfer orbit, with a functional payload (rover, probe or capsule), tomorrow to show that even this is possible.

[r4pt0r]

Is it possible to edit the "PSA" part out of the thread title

[ZooNamedGames]

I have a suggestion to improve the "Eve Atmosphere Challenge". Try to aim for 60km Peri, then make multiple layers of heatsheilds. I suggest using the 5m which leads to a 2.5m hestsheild and if still needed, decouples to a 1.25m heatsheild.

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[quote name='r4pt0r']Is it possible to edit the "PSA" part out of the thread title[/QUOTE]

Yes, for the Jeb, yes please.

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[quote name='Gaarst']Kudos to Ferram for a simple yet efficient demonstration.
Still, if no one has done it then, I will try direct aerocapture from a Kerbin-Eve transfer orbit, with a functional payload (rover, probe or capsule), tomorrow to show that even this is possible.[/QUOTE]

Its about as impossible as a happy wheels impossible level.

[problemecium]

"impossible"

I understand the troubles it's been providing, but hey, this is KSP. It CAN be done. Perhaps with lots and lots of retro-rockets.

[ZooNamedGames]

[quote name='parameciumkid']"impossible"

I understand the troubles it's been providing, but hey, this is KSP. It CAN be done. Perhaps with lots and lots of retro-rockets.[/QUOTE]

Not even that is needed.

[Tourist]

[quote name='parameciumkid']"impossible"

I understand the troubles it's been providing, but hey, this is KSP. It CAN be done. Perhaps with lots and lots of retro-rockets.[/QUOTE]

Exactly, its now an engineering problem. I managed to de-orbit a spaceplane onto Eve yesterday... just had to slow it down during descent by burning retrograde. No ablator needed.

My understanding is that Eve and Tylo are [B]supposed [/B]to be late career challenges. Now, Eve at least, is living up to that destiny.

[Pixel Kola]

Am I just crazy or doesn't time-warp exaggerate heating effects similar to how time-warp exaggerates air-intake?? That could be your flaw. Otherwise, you need to get into thicker atmo sooner.

[Endersmens]

Yeah guys, lower peripasis makes Eve entry very much possible. This thread needs to be edited, because it's utterly untrue and claims to be "confirmed."

'Tis a bit misleading. :)

[federicoaa]

For reentry, either too high or too low PE will result in your craft exploding, you need to find a good altitude, that's all.

[Pthigrivi]

How many of these aero qq threads are we going to see?

Ive done it. Lots of people have done it. Its not impossible, its not even that hard. You're coming in too steep.

[stupid_chris]

[quote name='Xyphos']Hadn't tried it, but I expect more drag and more heat and faster burn up[/QUOTE]

Problem is shock heating is not caused by drag. Heat caused by friction with the air is a few orders of magnitudes lower than shock heating. I don't think you're fully understanding what you did wrong, but it's very possible if done properly.

More drag would be a *great* thing, it'd slow you down faster and cause you to get to speeds that stop shock heating.

[ferram4]

[quote name='Pthigrivi']How many of these aero qq threads are we going to see?

Ive done it. Lots of people have done it. Its not impossible, its not even that hard. You're coming in too steep.[/QUOTE]

Except he's not. He's coming in too shallow. My post on the first page was taking his vehicle and coming in steeper, which allowed it to survive. This kind of statement is what leads to people like OP taking a ridiculously shallow trajectory like he showed, blowing up, and then declaring that reentry is impossible. The fact is, it's not.

[Starwaster]

Yeah, too shallow by far.

And not only is Eve easily survivable from Eve orbit, it's pretty easy on a Kerbin->Eve transfer.

You've got to try HARD to mess up an Eve reentry.

[cyberpawn]

Re-entry is possible.. Return to kerbin is impossible.. -Me lol

[Streetwind]

It's the same thing I keep preaching... scooting up to the very edge of the atmosphere and then timidly lowering yourself in is [I]not[/I] the most gentle and cool way of reentry. That process simply results in spending the maximum amount of time with a low vertical velocity in the high reaches of the atmosphere that are too whispy to slow you down yet perfectly capable of cooking your ship (see: real life Mars EDL problem), before dropping you like a rock with ever-increasing vertical speed into the lower reaches where you ship gets torn apart by losing altitude much more quickly than speed.

If your apoapsis before reentry is higher, you can blitz through the useless upper reaches with a high vertical velocity, before leveling off at your chosen periapsis in a regime of the atmosphere that provides useful amopunts of drag to slow you without generating overwhelming amounts of heat. Your g-forces are also going to be much more uniform and tolerable. Similarly, if you must start with a low apoapsis, then at least drop your periapsis low to accelerate your initial descent and try to get some body lift going in the lower reaches. Edited November 18, 2015 by Streetwind

[KerikBalm]

[url]http://forum.kerbalspaceprogram.com/threads/139815-Re-entry-on-Eve-impossible-due-to-overheating?p=2300792&viewfull=1#post2300792[/url]


Confirmed, Reentry on Eve is possible. Returning to orbit from eve with the same craft is also possible.

almost the saem picture set, this time showing the resulting orbit after returning to orbit:
[url]http://forum.kerbalspaceprogram.com/threads/139099-Any-luck-lifting-from-Eve-since-1-0-5?p=2296526&viewfull=1#post2296526[/url]

No shenanigans of part clipping or inverted nose cones or any of that were used.

[Kobymaru]

[quote name='ferram4']Starting from a 100 km orbit, dropping periapsis to 7 km (expending 100 m/s of dV retrograde), your vehicle ends up like this:

[URL]http://i.imgur.com/WkYtoc8.png[/URL]

Your reentry periapsis was simply too high and didn't bleed off enough speed. The problem is your procedure, not Eve. I'll also note that since I left the RCS off besides for initial orientation, I likely had more mass than you during the entire reentry, so I should have had more heating.[/QUOTE]

[quote name='ferram4']Except he's not. He's coming in too shallow. My post on the first page was taking his vehicle and coming in steeper, which allowed it to survive. This kind of statement is what leads to people like OP taking a ridiculously shallow trajectory like he showed, blowing up, and then declaring that reentry is impossible. The fact is, it's not.[/QUOTE]
Ok, so I've heard this a few times now, and I totally believe you. But I still don't understand it. Can you explain it to me again?
Also, please explain it like I'm 5 years old.


[quote name='Streetwind']It's the same thing I keep preaching... scooting up to the very edge of the atmosphere and then timidly lowering yourself in is [I]not[/I] the most gentle and cool way of reentry. That process simply results in spending the maximum amount of time with a low vertical velocity in the high reaches of the atmosphere that are too whispy to slow you down yet perfectly capable of cooking your ship

If your apoapsis before reentry is higher, you can blitz through the useless upper reaches with a high vertical velocity, before leveling off at your chosen periapsis in a regime of the atmosphere that provides useful amopunts of drag to slow you without generating overwhelming amounts of heat. Your g-forces are also going to be much more uniform and tolerable. Similarly, if you must start with a low apoapsis, then at least drop your periapsis low to accelerate your initial descent and try to get some body lift going in the lower reaches.[/QUOTE]
Perhaps this is a question that requires a math-explanation, but I'm gonna try it qualitatively.

It's not like any of the KSP atmospheres is layered, so I assume it's completely uniform with the pressure following an exponential function, correct?
Now what is it that makes the higher regions "too whispy to slow you down yet perfectly capable of cooking your ship" and why does it not apply to the lower layers?

In my head, the total amount of energy should be the same. So when you spend more time in higher layers, you brake the same amount, but spread out over a longer period of time. This gives the ship more time to radiate the heat and should lead to safer reentry.
As mentioned by people, this is wrong. But why???

How can I bleed off more speed in the lower atmosphere with less heating?


ps.: Suggestion to our Eve heroes: what if you turn the explanations and suggestions and the math into a sticky posts? There are way too many people complaining that Eve reentry is too hard, and instead of proving them wrong over and over, we should just have one sticky.