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Re-entry on Eve impossible due to overheating

Makki

By Makki
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Makki

Makki

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Posted (edited)
Edit: So I wrote this thread, but I couldn't submit it because I wasn't logged on. Then I logged on and rewrote the entire thing only to find that people had replied to it before I even submitted it.. what is going on?

Edit 2: Nevermind the mods figured it out. Thanks.

Edit 3: Title is misleading. I've come to realize that it's not "impossible" to land on Eve. I just had to lower my periapsis upon decent which would give my ship a smaller velocity going through the atmosphere. I should also have placed my heatshields on the opposite side of my ship to prevent it from flipping as it did.

Hey guys I've been trying to land and return from Eve now since May this year. I've tried a few designs but none of them worked. The biggest issue with my missions to Eve were not the ascent, but rather the descent to Eve's surface simply due to overheating. I've had to give up (or at least stall) my mission now since I figured it's just not possible to get a suitable lander to the surface without it literally exploding. (atleast in the current update)

Note: I play with Re-entry heating at 100%

Note: I play stock KSP (no mods)

Note: How do I spoiler-tag images?

Here's an example which occured today. Keep in mind if any of you guys have suggestions or solutions as to why my craft overheats you are more than welcome to educate me.

Here's my lander. I copied it from another thread I found somewhere in the forums. It's said to be able to ascent from Eve, but I haven't tried yet.
[spoiler=Click to view][IMG]http://i.imgur.com/BeP01Cn.png[/IMG][/spoiler]

The lander in the picture weighs 138 tonnes with landing gear, parachutes and heatshields.

It also has some airbrakes for better braking through the atmosphere:
[spoiler=Click to view][IMG]http://i.imgur.com/4WnwPfF.png[/IMG][/spoiler]

Here is the transfer stage I used to get from Kerbin to Eve. Total weight in orbit 967 tonnes:

[spoiler=Click to view][IMG]http://i.imgur.com/lsuxGW8.png[/IMG][/spoiler]

The transfer stage has a total delta-v of 4632 m/s . More than enough from Kerbin to Eve and get a circular orbit.
The mission went fine so far and I managed to get a good orbit around Eve. I lowered my apoapsis to 95 km and lowered my periapsis to 60 km.
Thus began my descent.

Here's a picture at an altitude of 74 km:
[spoiler=Click to view][IMG]http://i.imgur.com/9oYPzHB.png[/IMG][/spoiler]

My ship is already burning hot and it has also tilted a little bit to the side, but I tried preventing that by using SAS to keep my ship pointing away from the heat, without success.

Here's a picture of the ship at an altitude of 71.4 km
[spoiler=Click to view][IMG]http://i.imgur.com/UYSS2Kb.png[/IMG][/spoiler]

At this point my Airbrakes have somehow exploded due to overheating even though their job was to prevent it...
Also why doesn't my heatshields work. Like seriously...
And notice to the left how my 4 main engines are overheating? They are placed directly behind the heatshields... there should be no way for them to overheat this way?!?! Geez I'm getting frustrated just writing this now.

[spoiler=Click to view][IMG]http://i.imgur.com/zY2nCTC.png[/IMG][/spoiler]

And then the inevitable happened. My ship didn't even get below 70 km. I just don't know what I'm doing wrong. I though Squad fixed this with their recent "Thermal Improvement" update.

And yes I know I could just reduce the heating upon re-entry but I consider that cheating.. Might aswell remove it entirely then.

Seriously though, this has been the most frustrating problem since I started this mission. KSP is such a fun game, but this needs to be fixed. Otherwise I don't think I'll be playing for much longer. Edited by Makki
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Project Pluto

Project Pluto

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I only land small probes, so I don't know if my solution will apply to a much larger craft. I've been encasing my Eve landers in a fairing with heat-shields below. Once through the worst of the atmosphere, jettison fairing, jettison heat-shield, deploy chutes when safe, land softly!

Edit: Doubt you'll get a stock fairing over your lander. May need to redesign or grab a mod.
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Xyphos

Xyphos

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using I-Beams in a hexagon, build a massive heatshield from the 3.5m shields, set your aerobreaking manuver to 85km and adjust your AOA for a longer breaking time. usually, I'll areobreak clear halfway around EVE before re-ascending for the insertion burn.
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HyperbolicKerbonaut

HyperbolicKerbonaut

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I'm no expert on Eve missions, but from the looks of it, the problem is that your vessel is pointed away from the retrograde marker, meaning that anything above the shields is subject to the atmospheric heating. This might explain why your engines are heating, since if your vessel if tilted far enough the engines won't be protected by the heat shields.

But I gather you know that and want to know how to fix it.

I think you have two options, one easy, the other hard:

EASY: You can add more ASAS modules. This will help keep your craft stabilized during descent. Just make sure you have enough battery capacity to maintain stability.

HARD: Your craft is apparently unstable in atmosphere. You need to redesign. I'm not sure what exactly you need to do. It might be a mass distribution problem. It might also be that you need to add some wings to the lower portion for stability. I'm also curious whether the tilting problem happens before or after you activate the airbrakes. I seem to remember having an issue with airbrakes flipping my craft because I had them positioned too low. If you look at how the Space-X rocket handles re-entry, it has the airbrakes way at the top of the craft ([img]http://rack.2.mshcdn.com/media/ZgkyMDE1LzAxLzI5LzIxL3NwY3g5ODcwZGZkLjhjNTBjLmpwZwpwCXRodW1iCTEyMDB4OTYwMD4/12b8c401/0da/spcx9870dfd.jpg[/img], but yours are in the middle. I wouldn't activate the airbrakes until my speed was sub 2000. They're designed to slow airplanes, not interplanetary vessels; it makes sense that they're blowing up early.

I would run a few tests on Kerbin to see what the problem is.

Hope that helps. Edited by HyperbolicKerbonaut
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Foxster

Foxster

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Posted
Yea, Squad really messed the heating with 1.0.5.

It was supposed to fix that aerobraking didn't work at places like Eve and Jool. Instead it made things worse in that you can't land even from orbital speeds now.

Too busy testing little jet engines I guess.
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Makki

Makki

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Wow I just realized my posts won't be visible until a moderater has approved it (why though?). To the mods out there; Just ignore my last few posts and just keep my original post if that makes sense.
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Pecan

Pecan

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Posted
[quote name='HyperbolicKerbonaut']...If you look at how the Space-X rocket handles re-entry, it has the airbrakes way at the top of the craft...[/QUOTE]

Pah, space-X, what have they landed lately? [URL="https://xkcd.com/1244/"]Obligatory XKCD[/URL]
(Come on Elon, I've got a bet on and can't wait to collect)
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KerikBalm

KerikBalm

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Foxster... stop saying you can't land from orbital speeds now.
Since 1.05 I've done a descent on jool down to kraken depths.
I also did a deorbit and reorbit from eve (though I used HE to get to eve orbit)

Deorbiting on eve is fine if you have heat shields:

[img]http://i.imgur.com/3kuz31t.png[/img]

[img]http://i.imgur.com/nOcCmSv.png[/img]

[img]http://i.imgur.com/QKxChH8.png[/img]

[img]http://i.imgur.com/RDcxLHS.png[/img]


Unlike in 1.02.. we actually have situations where the heat shields are needed.
The heat shields have a purpose now, use them.
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HyperbolicKerbonaut

HyperbolicKerbonaut

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Posted
[quote name='Pecan']Pah, space-X, what have they landed lately? [URL="https://xkcd.com/1244/"]Obligatory XKCD[/URL]
(Come on Elon, I've got a bet on and can't wait to collect)[/QUOTE]
I've never seen that, that's hilarious!

[COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]

[quote name='KerikBalm']Foxster... stop saying you can't land from orbital speeds now.
[/QUOTE]

The problem is the OP is using heat shields. How is your craft different from his? From what I can see, yours is more stout and has more airbrakes. Is that accurate, or is something else at play?
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Deadpangod3

Deadpangod3

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Posted
[quote name='HyperbolicKerbonaut']I've never seen that, that's hilarious!

[COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]



The problem is the OP is using heat shields. How is your craft different from his? From what I can see, yours is more stout and has more airbrakes. Is that accurate, or is something else at play?[/QUOTE]

OP is rotating his ship so its not behind the heatshields, i believe that is the cause.
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Xyphos

Xyphos

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Posted
[quote name='Foxster']Yea, Squad really messed the heating with 1.0.5.

It was supposed to fix that aerobraking didn't work at places like Eve and Jool. Instead it made things worse in that you can't land even from orbital speeds now. [/QUOTE]

shouldn't that be an atmospheric density issue and not a heat issue?
and if aerobraking wasn't allowed, how are we supposed to land on these planets? it's nearly impractical for stock parts to have 8000+ dV on an upper braking stage plus lander and return vehicle.
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Foxster

Foxster

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Posted
[quote name='KerikBalm']Foxster... stop saying you can't land from orbital speeds now.
[/QUOTE]Oh, don't spoil my fun, I enjoy moaning about KSP being just slightly less than perfect! (:wink:)

Here's my 50t Eve lander and re-orbiter just posted in Spacecraft Exchange: [URL]http://forum.kerbalspaceprogram.com/threads/139830-The-Eve-OH-1-0-5-Eve-lander-and-orbiter?p=2300929#post2300929[/URL]
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brianorca

brianorca

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Posted
[quote name='HyperbolicKerbonaut']I've never seen that, that's hilarious!

[COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]



The problem is the OP is using heat shields. How is your craft different from his? From what I can see, yours is more stout and has more airbrakes. Is that accurate, or is something else at play?[/QUOTE]
The OP ship is aerodynamicly unstable when flying backwards. It needs more drag at the top, which is backwards from our normal launch aerodynamics. You also need a way to shift that drag to the rear again for your ascent.
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problemecium

problemecium

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Come to think of it, SQUAD DID say they were changing the aerodynamics to make it easier to aerocapture around Eve and Jool... in light of which I expect yet another atmosphere adjustment in the near future to nerf the excess heating at high altitudes. I can handle it, but when my airbrakes are all blowing up even when undeployed, and every other part is coming within a few single degrees of exploding, it feels a little mean xD
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AeroGav

AeroGav

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[URL=http://s1144.photobucket.com/user/narostel/media/LVN%20Mod%201%20test/2015-11-15_00001_zpsvuzhgp6a.jpg.html][IMG]http://i1144.photobucket.com/albums/o492/narostel/LVN%20Mod%201%20test/2015-11-15_00001_zpsvuzhgp6a.jpg[/IMG][/URL]

Have to say I'm in agreement with OP - the heating on Eve is now too strong. I circularised at 93-95 AP - Periapse then did a burn down to 88km. Round and round and round we went, nothing happenning. Then at 77KM all hell breaks loose. Ship blows up less than 10 seconds after the heat bars appear. My best attempt was by burning radial at 82km till , at 2800m/s, i no longer had the thrust:weight ratio in my 3 LV-N to resist Eve's gravity. I shut two and three off and kept the left going full bore to put me in a flat spin. That delayed blowup to 72km. Eventually I hit Alt F12 and ticked the "ignore overheat" box. The atmosphere thickens so dramatically between 80 and 70km. At 71km it is thick enough for me to stop my descent with only 10 degrees AoA (was doing 2950m/sec at the time).

This plane has no problems with Kerbin , it can also re-enter and land on Duna. It has lots of wing area (stall speed under 30m/s on Kerbin) and normally is able to skim the top of the atmosphere and avoid the worst of the heating.

But on Eve it's nowhere close to surviving. I can't see a few radiators in cargo bays making a difference, anyone planning to add more , needs to consider the small matter of acheiving orbit again ! And ablators aren't available for aircraft , unfortunately.
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Tourist

Tourist

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I have noticed a bit of an issue getting a plane to deorbit on Eve. Ultimately though, Squad can't win.

It initially creates the soup-o-sphere that makes it easy to get rockets into space, and the spaceplane builders complain the aerodynamics is borked. They tweak the aerodynamics to make spaceplanes fly more realistically, and the rocket builders complain that the game is unplayable and you can't aerobrake on Jool anymore. Squad tweaks again in compromise and the spaceplane builders complain the soup-o-sphere is back and the rocket builders still complain the of flipping rockets and you still can't aerobrake around Jool. It tweaks again to bring back peoples beloved Jool Aerobraking, and people complain its too deadly to de-orbit to Eve. Not to mention the constant tug of war between, more deadly re-entry please vs HELP re-entry is too deadly crowds.

I would not want to be in their shoes. Its lucky they don't pay too much attention to the forums, otherwise they'd be tearing there hair out, screaming "what do these people want!!!"

My answer to this is to take a philosophical approach. A change which makes something more difficult that was easier before is just a design challenge to overcome. When you couldn't aerobrake around Jool anymore, the challenge was to design a craft with enough delta-V to slowdown. I landed a plane on Eve immediately after the change.... it meant I had to burn retrograde to slow down and subsequently lost control of the plane because I needed the fuel to balance the plane. This just means I need to overcome this problem. My plan (untested) involves a deorbit/slowdow stage, ablators, and a parachute on the back to flip it around the right way. Edited by Tourist
post-editing, making word work gooder.
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