How to land at Eve???

[Kerbals_of_Steel]

My first career save has given me a series of Eve contracts, trying to knock them out and make my first interplanetary landing. Since Eve is vaguely Venus, I decided to make a vaguely Russian probe: 

 

Eve entry is a hell of a thing. A 60-65km approach captures into orbit, but I run out of ablator and nearly cook everything on the second pass. 50-55km simply cooks it on the first pass. I've mostly landed them (except for my first, 45km attempt, which was like belly flopping into wet concrete...) but they have been zero-margin results. I'd like to figure out how to put a little more insurance into the mission before launching for "real".

 

I really like how this thing looks, and at 50K kerbucks for an interplanetary mission, it's very career friendly, but how do people land on Eve without bouncing ALL the heatbars off the redline?

HALP!!!

Edited February 22, 2021 by Kerbals_of_Steel

[18Watt]

I avoid Eve’s atmosphere at all costs, so take my suggestions with a grain of salt.

One suggestion is use rocket engines to slow down at Eve, instead of relying on aero braking to cover 100% of your DV needs.  

Another suggestion which works for me on Kerbin and Laythe (but may not apply at Eve..)- A steeper entry profile often actually reduces overheating problems- if your ship can handle the g-loads.  The idea is to spend less time at high altitudes, where you generate a lot of heat from friction, but not much drag.  A steep entry takes you to the soupy air quicker, so you decelerate quicker, before your ship has time to heat up.

Or maybe bring two or three heat shields?  However many it takes.

[The Aziz]

You're making a landing approach at lightspeed  interplanetary speeds? I'd never do that on Eve, the atmo is just hell indeed. Bring one more stage (and maybe give a little more oopmh to the lifter if needed), since the payload is relatively small, it shouldn't be a problem, and capture into orbit using engines, not aerobraking (or at least partially)

Edited February 22, 2021 by The Aziz

[Guest]

Eve is a zero-margin kind of place. Congrats on succeeding at full aerocapture/aerobrake, that’s not easy at all.

If you really do want to increase your margins, the easiest way is to burn off a few hundred m/s by burning retrograde. Another option is to redesign your craft to be less dense — either a bigger heat shield or less stuff behind it.

[magnemoe]

Very good looking probe  

And you can aerobrake into orbit but I prefer to use a bit of dV to get into an highly elliptical orbit where you can lower Ap with multiple aerobrake burn until you get into low orbit followed by landing. 
Using an larger heatshield helps even an inflatable one 

[Snark]

Moving to Gameplay Questions.

12 hours ago, Kerbals_of_Steel said:

I really like how this thing looks, and at 50K kerbucks for an interplanetary mission, it's very career friendly, but how do people land on Eve without bouncing ALL the heatbars off the redline?

Actually, I find that Eve is just about the easiest place in the system to land on-- if it's an uncrewed, one-way trip.  (Actually taking off from the surface and returning to orbit, on the other hand, is extremely challenging-- but that's another story.) 

By "easy", what I mean is,

• requires very little dV to get to from Kerbin, in interplanetary terms
• requires no dV on arrival, due to aerobraking
• as long as you're appropriately heat-shielded, reentry is no problem at all
• the atmosphere is so think that just a small amount of parachute capacity will land you gently and reliably

That said-- if you haven't done it before, there are a few gotchas that you could easily run afoul of, so it's totally understandable if you're running into problems.  A few thoughts:

12 hours ago, Kerbals_of_Steel said:

A 60-65km approach captures into orbit, but I run out of ablator and nearly cook everything on the second pass.

Yeah, don't do that.  Multi-pass aerobraking is almost always counter-productive.  You'll do better going in a single pass.

11 hours ago, 18Watt said:

Another suggestion which works for me on Kerbin and Laythe (but may not apply at Eve..)- A steeper entry profile often actually reduces overheating problems- if your ship can handle the g-loads.  The idea is to spend less time at high altitudes, where you generate a lot of heat from friction, but not much drag.  A steep entry takes you to the soupy air quicker, so you decelerate quicker, before your ship has time to heat up.

^ This.  Exactly this. 

There is a common (and very understandable) misconception about re-entry heating that a lot of newer KSP players run into.  It typically goes something like this:

• I need to do reentry.
• Eeep!  That's really scary-- it's gonna be super hot and I'm worried I'll explode!
• Okay, so, just to be on the safe side, let's eeeeeeease slowly into it.  I'll set a really high Ap so I can aerobrake very gently at high altitude where it's not so scary.
• ....hey!  why did I run out of ablator, get baked, and explode anyway?

That's an entirely reasonable way to think-- unfortunately, it happens to be wrong.    The counter-intuitive truth is,

You get much less re-entry heating if you dive deep into the atmosphere and brake hard, than if you try to "skim the top".

Here's why.  When you aerobrake, there are two things that happen:

1. You start heating up.
2. Drag slows you down.

Both of these things happen, and both of these effects get stronger (by a lot) as you go deeper into the atmosphere.  Where people go astray is that they think that the two effects are "tied together" and get stronger at the same rate with altitude.  They don't.  Heating becomes strong while still very high in the atmosphere, but drag doesn't become significant until you get much deeper down.

Therefore, if you try to "skim the top" by doing multiple passes at high altitude, what happens is that you heat up by a lot, but you hardly affect your speed at all.  You end up taking a lot more heat-per-amount-of-slowing.  It's gradual, sure-- you're getting slow-baked rather than blowtorched.  But it'll bake you nonetheless and leave you in a bad place.

Also:  KSP's heating model has the concept of a "skin" temperature and a "core" temperature.  Each part is rated for a max skin temp and a max core temp, and typically they can stand a significantly hotter skin temp than core temp.  If you reenter quickly, then the part's hot skin doesn't have much time to conduct to the core, so it's the (significantly higher) skin temp that limits your toughness.  But if you do reentry slowly, then the hot skin has plenty of time to conduct heat to the tender core, so you can end up exploding when the core overheats.  In short:  parts are tougher against intense, brief heating than they are against slow-baking.

By plowing right into the soup, you don't have as much time to build up heat, and you quickly get down to the very draggy part of the atmosphere that will slow you down quickly, and that will make the heat load less.

That said:  Don't overdo it.  If you dive too steeply, then the speed of heating can increase so quickly that the ablator can't boil off fast enough to deal with it.  There's a happy medium.

Basically, you want to aim your approach so that your Pe is as high as you can make it while still guaranteeing that you'll brake and go down in one pass.

Exactly how high that is will somewhat depend on the design of your ship, but in general I've found that the "right" aerobraking altitude for Kerbin is around 30 km, and for Eve is around 55-59 km or so.

12 hours ago, Kerbals_of_Steel said:

50-55km simply cooks it on the first pass.

I'd suggest around 58ish km for your Pe.

As to why it cooks on the first pass-- that shouldn't happen, that sounds like a ship design issue.

I don't recognize that part that you have attached directly behind the heat shield.  What is its temperature tolerance?

Reason I ask:

Heat shields do a great job of shielding your craft from re-entry heat.  They have a very high heat tolerance, they've got ablator, and they have a fairly low thermal conductivity.

However, even with all of that, the heat shield does get very hot during reentry, and any part that is directly touching the heat shield needs to be able to handle a reasonable amount of temperature.  For example, some parts have a lower temperature tolerance, like 1200K -- putting such a part in direct contact with the heat shield would likely cause it to blow up, with catastrophic consequences.  On the other hand, a part that can handle over 2000 K would likely be fine.

In short, the temperature tolerance of the part that's directly attached to the heat shield, matters.  Most parts should be fine, but some are not.  Is there a chance you may have a low-tolerance part there?  What happens if you insert another part (such as a Z4K battery, or even just another heat shield with ablator removed to save weight) in between the heqt shield and that part?

Two other questions that may be useful in diagnosing what's going on:

• When you do reentry at a Pe of 55 km and you blow up, what does the F3 dialog say?  That can be quite informative at understanding exactly what goes wrong.
• Try turning on the F11 temperature overlay while reentering.  Does it show anything unexpected?  (e.g. a part getting anomalously hot that you wouldn't have expected, or something)

12 hours ago, Kerbals_of_Steel said:

(except for my first, 45km attempt, which was like belly flopping into wet concrete...)

Yeah, Eve's atmospheric braking profile is a little... odd.  I've noticed that it seems to have a "wall" at around 45 km where the drag abruptly gets incredibly high.  Dunno why.

I usually aim for a braking Pe in the upper 50's, which mostly takes care of the really hot part of reentry.  Then when the craft gets down to 45 it decelerates really hard, but that's less of an issue.

[Snark]

Oh, one other question, @Kerbals_of_Steel.  In that one pic of reentry where the navball is visible, it looks as though you're not pointed perfectly straight .  Is there a reason for that?  You want your craft to be pointed perfectly to ensure that all the parts are safely sheltered inside the "shadow" of the heat shield. It looks like you have all the SAS modes available, so I'd strongly suggest that you set your SAS to "hold " in order to ensure you're kept oriented properly. 

I'd also suggest that you switch the navball to "surface" mode rather than "orbit", because the atmosphere is moving at zero surface speed, so holding to "surface " is the entry attiude you want.

 

If the reason you're not is because you can't-- for example, if your craft isn't quite aerodynamically stable for some reason, so it "wants" to wander away from a orientation and you don't have enough control authority to force it to the correct orientation-- then that could be another concern worth addressing.

 

[king of nowhere]

37 minutes ago, Snark said:

Yeah, don't do that.  Multi-pass aerobraking is almost always counter-productive.  You'll do better going in a single pass.

 

There is a common (and very understandable) misconception about re-entry heating that a lot of newer KSP players run into.  It typically goes something like this:

• I need to do reentry.
• Eeep!  That's really scary-- it's gonna be super hot and I'm worried I'll explode!
• Okay, so, just to be on the safe side, let's eeeeeeease slowly into it.  I'll set a really high Ap so I can aerobrake very gently at high altitude where it's not so scary.
• ....hey!  why did I run out of ablator, get baked, and explode anyway?

That's an entirely reasonable way to think-- unfortunately, it happens to be wrong.    The counter-intuitive truth is,

You get much less re-entry heating if you dive deep into the atmosphere and brake hard, than if you try to "skim the top".

 

strange, as those are directly opposite to my long experience at this game...

though, upon considering it, i finally realized why my experience is different: i do not use ablators. not much for a conscious design choice, but i tend to build everything reusable, and ablator is not reusable. i can't make a reusable eve ssto, but i still drop stuff that's meant to launch to orbit again, and that's big enough to require the inflatable heat shield, which has no ablator.

if you have no ablator, then the gentle aerobrake is better. the lower part of the atmosphere is always worse, and any amount of slowing you can get before that is welcome.

if you have ablator, then the lower atmosphere is still worse, but at least you'll have ablator to protect you. if you try for a gentle aerobrake, you will run out of ablator and then you'll be exposed in the lower atmosphere. and the braking in the high atmosphere will still be minimal. same goes for multi-pass aerobraking.

you can land on eve without ablator. but you need to be gentle to make it work; first capture into an elliptic orbit, then gradually lose speed. make the final reentry from a low circular orbit. be ready to see red bars all over your vehicle. in my case i used rocket burn for capture, and then i gradually burned some speed at every orbit, something like 20-40 m/s at every pass over several days.

[Snark]

1 hour ago, king of nowhere said:

if you have no ablator, then the gentle aerobrake is better.

Depends a lot on the craft and the circumstances-- and also depends on what you mean by "gentle". 

A craft without ablator won't be able to take as much direct punishment as one that does.  However, it's still the case that people have run into trouble by trying to take it too "gently" with very high-altitude passes and ended up cooking themselves, where a deeper trajectory would have been fine-- even without ablator.

It's also worth noting that heat shields do a pretty good job (much better than other parts) at heat shielding, even when they don't have any ablator on them.  Their temperature tolerance is a thousand degrees or more higher than just about anything else, and they have very low thermal conductivity.  (Yes, they do better with ablator... but even a ship with an ablatorless shield will be a lot tougher at reentry than a craft with no shield at all.)  So it's not just about ablator, per se.

[king of nowhere]

3 minutes ago, Snark said:

Depends a lot on the craft and the circumstances-- and also depends on what you mean by "gentle". 

A craft without ablator won't be able to take as much direct punishment as one that does.  However, it's still the case that people have run into trouble by trying to take it too "gently" with very high-altitude passes and ended up cooking themselves, where a deeper trajectory would have been fine-- even without ablator.

i've never seen it happen, but I have seen something that can be mistaken for the same: a ship brakes too much in high atmosphere, then its trajectory changes to a steep descent, going too fast too low and burns. while another ship stays in the middle atmosphere long enough to slow down more before going low. but it's never "prolonged exposure to high atmosphere aerobraking" that does damage; it's a secondary consequence of that, namely, you fall down too fast

Quote

It's also worth noting that heat shields do a pretty good job (much better than other parts) at heat shielding, even when they don't have any ablator on them.  Their temperature tolerance is a thousand degrees or more higher than just about anything else, and they have very low thermal conductivity.  (Yes, they do better with ablator... but even a ship with an ablatorless shield will be a lot tougher at reentry than a craft with no shield at all.)  So it's not just about ablator, per se.

thermal shields are ridiculously sturdy. at least, they are for someone regularly used to not using them. i recently made a reentry at 9 km/s, got hit by 37 g deceleration, was fine. and i didn't even use half of my ablator for it. using ablator should be overkill for most manuevers.

but some ships are not fully covered by those shields. maybe they have some bits spreading out, and that's the part that breaks. or maybe they are aerodinamically unstable, and too much drag will make them flip. or maybe they have sensitive parts attached to the shield. or maybe the ship is very big and the shield small... there are a lot of reasons an aerobraking can go wrong, without them being the fault of the shield or the ablator themselves

[Guest]

My experience is kind of between @king of nowhere's and @Snark's. I fly a lot of planes, especially to Eve, and other than having a holy terror of attempting aerocapture with them, I do think two passes to bring down the Ap before doing final re-entry does work better with them. But if it has a heat shield and it's built to withstand the "belly flop into concrete" you get at 45k then yeah single-pass is the way to go.

(But I usually end up burning a bunch of fuel retrograde in any case. I always design my transfer stages with a bit of extra,  even if the craft is designed primarily for aerobraking, and it makes a big difference with Eve.)

[VoidSquid]

14 hours ago, Kerbals_of_Steel said:

A 60-65km approach captures into orbit, but I run out of ablator and nearly cook everything on the second pass

Hope I understand you correctly, you're directly diving in Eve's atmo, not from a orbit of say 100x100 km? From the latter, I never had issues to land any probes with heat shields, lowing the Pe to some 70k.

[Spricigo]

59 minutes ago, king of nowhere said:

strange, as those are directly opposite to my long experience at this game...

I'm guessing there, but if early on you stumbled into a method that "just works" the concessions you make for this method to work just seems natural for you. Developing a different procedure latter seems harder and if you really don't need it...

 

Anyways, there is many ways to cook a Eve probe. Myself, I'm found on pancake shaped vessels that can "belly flop into concrete" 

[Snark]

6 minutes ago, king of nowhere said:

thermal shields are ridiculously sturdy. at least, they are for someone regularly used to not using them. i recently made a reentry at 9 km/s, got hit by 37 g deceleration, was fine. and i didn't even use half of my ablator for it. using ablator should be overkill for most manuevers.

  I've actually never seen any circumstance where I need even close to a full load of ablator-- they seem to come with way more than they need.  Regardless of ship and regardless of planet, I generally always reduce my ablator in the VAB to 10% or 20% in order to save mass.

About the only time that I ever leave a full load of ablator on is if I have an awkwardly designed ship whose CoM is a bit farther behind the shield than I'd like, so I have concerns about aerodynamic stability-- so I may leave on the extra ablator as "ballast" to move the CoM closer to it and make it more stable.  More mass equals lost dV, of course, so I generally don't do this if I can avoid it; it's a technique I generally use only in extremis when there's something awkward about the craft design that I can't manage to work out some other way.

9 minutes ago, king of nowhere said:

but some ships are not fully covered by those shields. maybe they have some bits spreading out, and that's the part that breaks. or maybe they are aerodinamically unstable, and too much drag will make them flip. or maybe they have sensitive parts attached to the shield. or maybe the ship is very big and the shield small...

All of those can be problems, yes, but my answer to that essentially boils down to "Well then don't". 

A properly heat-shielded ship is incredibly tough against reentry.  However, this means that you shouldn't have any bits that stick out.  And it must be aerodynamically stable.  And it shouldn't have anything melty directly attached to the heat shield.  And you shouldn't have a big fat ship that's wider than the shield is.

If you can't design to ensure those things, then it's not really "heat shielded".  My answer to that would be, either ensure those things and go with a heat shield, or else (if it's impractical for some reason) then ditch the shield and come up with some other strategy for reentry.

[VoidSquid]

3 hours ago, Spricigo said:

there is many ways to cook a Eve probe

Well said and true. If possible and reasonable/required, I usually try to get as much energy out of the system as I can, i.e. entering the atmo from a low Eve orbit, instead of slamming in directly say from an interplanetary transfer.

Edited February 22, 2021 by VoidSquid

[Kerbals_of_Steel]

1 hour ago, Snark said:

  Snip.

The part in question is a Soyuz cargo fairing from Universal Storage and was chosen specifically because of a fairly good heat rating. Your talk about transferred heat has given me an inkling as to the root cause, and I will check it out next time I play.

Thank you, everyone for the advice so far!!!

[Dr. Kerbal]

I have only landed on Eve 3 times. 2 were landers like Hugyens. However on was a rover mission.

[king of nowhere]

3 hours ago, Spricigo said:

I'm guessing there, but if early on you stumbled into a method that "just works" the concessions you make for this method to work just seems natural for you. Developing a different procedure latter seems harder and if you really don't need it...

 

Anyways, there is many ways to cook a Eve probe. Myself, I'm found on pancake shaped vessels that can "belly flop into concrete" 

it's not that have found something that works. i have to jump through hoops all the times. it's just that i launch ships too complex to just strap a heat shield on the bottom and call it a day. i've never sent to eve anything that was not meant to come back, and that means a hundred tons launcher at least.

3 hours ago, Snark said:

All of those can be problems, yes, but my answer to that essentially boils down to "Well then don't". 

A properly heat-shielded ship is incredibly tough against reentry.  However, this means that you shouldn't have any bits that stick out.  And it must be aerodynamically stable.  And it shouldn't have anything melty directly attached to the heat shield.  And you shouldn't have a big fat ship that's wider than the shield is.

If you can't design to ensure those things, then it's not really "heat shielded".  My answer to that would be, either ensure those things and go with a heat shield, or else (if it's impractical for some reason) then ditch the shield and come up with some other strategy for reentry.

yes, i agree. i was trying to figure out why some heat shields fail when they shouldn't. i mean, i am trying to understand whence the advice "don't go for a gentle aerobraking, go for a more decise one" comes; for it is my experience that if you are not using a thermal shield with ablator, then the whole point is just wrong; and if you are using a heat shield properly, then you should never have a reentry problem, whatever you're trying to do, period. so I am suggesting it may be more of a case of improperly designed ship rather than a reentry profile

[Vanamonde]

That is a fancy probe, @Kerbals_of_Steel.   Have you tried a pass much higher, such as 80kms? Save the game and try multiple altitudes. 

Meanwhile, if you want to continue to use your existing design with a minimum of alterations, remember that each heat shield can be ejected separately without the need for a decoupler or stack separator. This means that on your existing design you could stack them and kick them off one by one as their ablator runs out. 

[Spricigo]

4 hours ago, king of nowhere said:

so I am suggesting it may be more of a case of improperly designed ship rather than a reentry profile

Personally, I don't see those as separated issue. The "correct" flight profile will be the one the vessel is designed to follow.

In my experience, the kind of craft the Op is using tend to work with the flight profile Snark is suggesting. Big landers intended to return from the surface not quite so.

[Snark]

19 minutes ago, Spricigo said:

In my experience, the kind of craft the Op is using tend to work with the flight profile Snark is suggesting. Big landers intended to return from the surface not quite so.

Actually, I tend to use that type of craft  with that type of profile even for big return-crew-from-the-surface landers.

The big inflatable heat shield is a godsend-- can easily fit an ascent-capable lander in a 10m footprint. It doesn't have ablator, though, so I usually use a bit of retro-thrust to slow somewhat from interplanetary speeds before hitting atmosphere.

The main challenge is keeping it aerodynamically stable.  I typically arrange it so that the big heat shield is on the bottom of the craft during entry (i.e. I'm facing during entry).  To maintain aero stability, I attach a disposable "weathervane" to the top of the craft-- tall and lightweight, festooned with airbrakes at the top end.  Those airbrakes serve the same function as the feathers on a badminton birdie, and do a great job of stabilizing the craft during descent.  The whole assembly is jettisoned as soon as it's through the hot part of entry.

(Airbrakes are very melty and can only take 1200 K, so they're not suited for hot reentry... except that the 10m heat shield is big enough that all the airbrakes fit inside its occlusion shadow, so they're not subject to heating and can simply do their job of producing loads of drag.)

[king of nowhere]

1 hour ago, Snark said:

The main challenge is keeping it aerodynamically stable.  I typically arrange it so that the big heat shield is on the bottom of the craft during entry (i.e. I'm facing during entry).  To maintain aero stability, I attach a disposable "weathervane" to the top of the craft-- tall and lightweight, festooned with airbrakes at the top end.  Those airbrakes serve the same function as the feathers on a badminton birdie, and do a great job of stabilizing the craft during descent.  The whole assembly is jettisoned as soon as it's through the hot part of entry.

(Airbrakes are very melty and can only take 1200 K, so they're not suited for hot reentry... except that the 10m heat shield is big enough that all the airbrakes fit inside its occlusion shadow, so they're not subject to heating and can simply do their job of producing loads of drag.)

the previous times i did it, i used a similar arrangement, but i used four big-S delta wings. those caused problems, though, because they tended to flip the rocket during launch. launching from kerbin was very hard. i didn't use airbrakes because i figured, with their low thermal resistance, they'd break. knowing they don't may save some troubles on future eve landers. I also include inflatable shields on the front, they help somewhat with aerodinamic stability by creating a drag in what will be the back of the ship, but without a "weathervane" they would just cause the ship to turn laterally instead. they are also pretty good parachutes, helping reduce speed.

 

descent profile was to use rocket brake for eve orbital capture (some 400 m/s) and gradual aerobrake to circularize to low orbit (some 1300 m/s). I used a 75 km periapsis, closer than 70 would have killed me. i only went below 70 in the final orbit, and even then, doing that too fast would have killed me. which is why i always object when i read the common advice "go deeper in the atmosphere, you'll get less heating", hell no, it only works on very specific kinds of crafts.

part of the problem, both for engineering and trajectory, was to leave an engine exposed. i needed some extra course corrections after the shields were deployed, so I needed an engine free to fire. so I had 4 shields at the bottom, and there was a small hole in them through which a mammoth could fire. Thinking of it, i could have probably added a terrier or poodle on the front for those manuevers, and jettison it before reentry. i could have aerobraked harder without that hole in the shields. the kill zone was at 50 km altitude, i needed to slow down a lot before reaching that low.

I describe the mission in greater detail in the kerbalism grand tour mission report linked in my signature, parts 3 and 5.2

Edited February 23, 2021 by king of nowhere

[Kerbals_of_Steel]

Firstly, would like to thank everyone for the suggestions, because each one I tried (that didn't require a fundamental redesign) worked.

@18Watt & @Vanamonde 's stacked heat shields? Worked.

@Brikoleur 's oversized heatshield? Ugly, but works.

@VoidSquid & @magnemoe retro plan? Same.

The grand prize goes to @Snark, though, for finding the root of the problem, which was in fact the root. (Also, order of operations, very important...)

Techno-babble in spoiler:

Spoiler

I present this on the off chance that some future spacefarer finds this useful. Hello from the past fellow spacefarer.

The main cause was a bit of sloppiness and inexperience on my part, and a weird edge case regarding the Universal Storage (highly recommended, excellent mod) parts I used for most of the probe. Universal Storage parts come in three basic categories, a center spine that is placed first, often under the command pod, various gizmos gadgets and greebles placed second via node attach,  and a fairing that snaps on last. Visual:

 

Since the probe I built didn't really have a traditional base part, I started with the fairing and snapped a center core into it, then built out from there. This was done basically for ease of construction, but it had an unintended consequence.  The assembled probe, note the 2900K heat rating for the fairing:

The probe with the center core removed. Most of the fairings are simple hollow shells, but this one includes nifty little dividing walls between the segments. (See the problem???)

Yup, all that yummy, melty sciencey deliciousness was inadvertently attached directly to a part with over twice the heat rating. Those parts with node attach were placed properly, but anything that surface attached had a 50/50 shot of being rooted on the correct part.  I then, in ignorance and with the best of intentions, proceeded to slow-roast the whole thing by specifically choosing to fly a slightly off camber AoA, resulting in enough lift that the probe hovered in that high atmosphere thermal murder zone. The fairing and it's 2900K heat rating were hot but ok. The delicate scientific instruments with a 1200K rating were well done.

The correctly assembled core and fairing:

Note how everything is attached to the central core now, adding at least one degree further of separation between the heat of reentry outside and the melty guts inside. (Two additional degrees of separation for the Gravioli and accelerometer since they are attached to the cubic strut that is attached to the center core.) But what about those cardboard boxes full of science in the other bay??? Well, those come from one of RoverDudes USI mods, and it turns out he has an, ummmm, optimistic opinion upon the thermal properties of a shoebox:

 

 

The end result is a probe that is visually identical to the first edition, but much more resilient. Combined with a somewhat altered flight profile ( Last minute retroburn to kill velocity and lighten the load by ~0.5 tons of fuel, more aggressive aerobraking, strict attention to attitude ), I've managed to get it to the surface with no more than routine amounts of heating. Or, maybe I'm just getting dulled to the terror of slamming into Eve's atmosphere at speeds somewhere between ludicrous and plaid, IDK...

Anyhow, I'm now confident enough to yeet this thing into space in career mode, and thanks to all for the advice, if I haven't used it yet, I suspect I will be soon.

 

KoS

[Spricigo]

3 hours ago, Snark said:

Actually, I tend to use that type of craft  with that type of profile even for big return-crew-from-the-surface landers.

Well, I play with extraplanetary launchpad. Which means  my lander are considerable smaller since they almost never include the return vehicle. And thus I didn't get a lot of practice with bigger landers. (made a few to know I can and that is it). 

I realize that there is something  I'm not getting right when scaling up, but beat me if can figure out what it actually is. (also, is not like I'm having trouble to bring  the extra fuel for a propulsive capture)

 

[Kerbals_of_Steel]

For anyone interested, I put up a slightly simplified version on KerbalX:

https://kerbalx.com/Mobryan71/Eve-Probe

Basically just took off some of the extra science that required non-critical mods. Still requires both DLC's and Universal Storage 2.