How Do You Deal with Inerplanetary Aerocapturing in 1.0.4?

[technicalfool]

Has anyone noticed the gigantor XL solar array's not withstanding aerobreaking/ aerocapture very well, or maybe I should say not withstanding aerobreaking/ aerocapture at all.

They aren't supposed to, and never have done. Any solar panels should be packed away before moving in an atmosphere, let alone aerobraking through it.

The non-retractable 1x6 and 2x3 panels (the ones that don't come with the protective box) shouldn't be used if you ever expect to aerobrake or re-enter with them intact.

[BDelacroix]

I haven't tried it in 1.04. I did in 1.0 and had no issues on Duna.

Has it changed that drastically?

As for the gigantor solar panel. THey do burn off with very little aero scuffing. While folded up. This much I know has changed recently. They are at 50% heat as soon as I hit the atmosphere. I wonder if they now intend we tuck them inside a cargo bay or something.

[FlowerChild]

1.0.4 introduced a whole new heat system which, from what I can tell of its inner workings, is considerably more rational and "realistic" than what we had in 1.0.2. So far, so good. But a set of equations is just a machine, mechanically crunching inputs into outputs. Thus, the results are only as good as the inputs. So the heat system must answer 2 questions. First, is the heat system a valid model for KSP and, second, what are the best inputs for it? When you reply to this thread, please try to answer both questions.

I spend a fair amount of time playing around with the heat system in my mod, so I think I am slowly developing a fairly good understanding of how both the 1.02 and 1.04 models function.

I think you're absolutely right in that it's difficult to balance for all planets simultaneously, which is why I personally favor the solution of having different heatshields for different purposes. So, a 1.25m heatshield might only be good for reentering small vessels (mass plays a big role in reentry survivability as it essentially determines how long you have to be able to handle it, since a heavier vehicle will decelerate less rapidly, but still sustain the same amount of heat per second at any given velocity and altitude) from LKO, a 2.5m might be good for a Munar return, and a 3.75 might be good for aerobraking at Jool.

I think the biggest problem the system is having right now is that all heatshields are trying to work for all purposes. Especially in career mode, having them be suitable for different things helps emphasize progression, and even in sandbox, it would introduce an additional vehicle design consideration in terms of the mass of shield you'd need for different things.

Of course, basing this on only 3 shield types becomes a bit of an issue, but I think if the number of shields were fleshed out more this could be a viable method of balancing heat in stock as well.

I haven't tried it in 1.04. I did in 1.0 and had no issues on Duna.

Duna has an extremely thin atmosphere, and thus is unlikely to ever be particularly deadly.

1.0.4 introduced a whole new heat system which, from what I can tell of its inner workings, is considerably more rational and "realistic" than what we had in 1.0.2. So far, so good.

Oh, on this point, I will disagree: I've spent a fair amount of time tweaking the 1.04 heat system now, and in comparison to that in 1.02, think that if anything it's just made thing much harder to understand what's going on from a player point of view, and also made it MUCH more difficult to balance as you're working with a greater number of variables that can have rather ambiguous interactions with each other. I really don't think it's added any perceptible depth or flexibility to the system either and am entirely uncertain why it was changed in the way it was.

Edited June 29, 2015 by FlowerChild

[Caelib]

I voted "Other" because I believe aerocaptures to be unrealistic and unnecessary when you can do a gravity brake

[Gaarst]

Voted other: I usually don't bother putting heat shields, I just hit the atmosphere and brake with drag. Trial and error for different altitudes if it does not work the first time

I don't do aerocaptures that often though, so it is not that of a problem for me.

[Sasquatch_Punter]

I still do it, but I'm smarter about it than I was. No more 2km/s vertical speed reentries on Kerbin. Honestly, I'm pretty happy about that.

It makes deorbiting stations a lot more fun, too.

[klesh]

I slap on a heatshield and find that only ~25% of it is needed. And then I shrug and wonder why they bothered adding re-entry heating.

[Frank_G]

I use the stock heatshields, attach docking ports to them and assemble larger constructs in orbit. I have just tested it for a Jool mission. Works very nice.

[Geschosskopf]

Has it changed that drastically?

In a word, "yes".

Between 1.0.2 and 1.0.4, we got a totally new heat system. The new system seems to be fundamentally more rational than the old but of course is quite new and in need of serious tweaking. Because one of the things the new heat system did was increase the amount of reentry heat for the same slider setting by a factor of about 4x (probably somewhere between 4-5x). Regardless of the underlying model, that is a dramatic change that has far-reaching consequences.

BTW, has anybody else noted how the maxTemp of many parts has been raised to 2400 in 1.0.4? I haven't seen anybody mention that. I do recall back in the early days of 1.0 that Squad said they'd lowered maxTemps to 2000 "for realism". I guess the retreat from that position is Squad recognizing that 1.0.4 makes too much heat so they did this in partial compensation. Still, a 20% increase in maxTemp compared to a 400-500% increase in heat leaves a lot to be desired and indicates the need for tweaking the 1.0.4 heat model.

[Mischief]

I admit, I'm confused where the current model is too hot. It takes a pretty insane reentry for heating to be deadly. Do you not want to use heat shields or radiators? Where are you finding that the new heat scale is high?

[Geschosskopf]

I use the stock heatshields, attach docking ports to them and assemble larger constructs in orbit. I have just tested it for a Jool mission. Works very nice

Remembering that the whole purpose of aerocapturing is just to save some fuel, how much did you end up saving afer deducting the costs of launching, docking, and carrying this structure to Jool? If I read the dV maps aright, the most aerocapture at Jool can save you is less than 2000m/s, rather less than the cost of launching something from Kerbin.

That's why I don't build big shields. To me, they're like using a $100K rocket to do a contract that only pays $50K. It's actually cheaper and MUCH easier just to use the "MOAR fuel" option and simply avoid touching atmospheres at interplanetary speeds. As Regex said, the KSP system is so small that the dV costs of going anywhere in it are not much of a deterrent, at least to anybody with a little experience. Not that I'm advocating rescaling KSP---that's what Orbiter is for. I'm just saying that the reward for interplanetary aerocapture is not big enough to justify extreme efforts to do it in the face of a hyperactive heat system.

[Dr Farnsworth]

They aren't supposed to, and never have done. Any solar panels should be packed away before moving in an atmosphere, let alone aerobraking through it.

The non-retractable 1x6 and 2x3 panels (the ones that don't come with the protective box) shouldn't be used if you ever expect to aerobrake or re-enter with them intact.

I have the gigantors retracted and they still explode like nuclear popcorn almost immediately upon entering the atmosphere.

[Blaster]

I admit, I'm confused where the current model is too hot. It takes a pretty insane reentry for heating to be deadly. Do you not want to use heat shields or radiators? Where are you finding that the new heat scale is high?

The answer, gentlemen, is to use more A.I.R.B.R.A.K.E.S. on your vehicle.

[Geschosskopf]

The answer, gentlemen, is to use more A.I.R.B.R.A.K.E.S. on your vehicle.

Are you sure this still works?

It certainly worked in 1.0.2. Enough airbrakes and your ship wouldn't make flames at all. But in 1.0.4, they reduced drag besides changing the heat model, so I've seen a different result. In my testing, I see no difference in heat at all between using airbrakes and not, at least at Jool. All the brakes do is lower your post-aero Ap. In theory, this could reduce heat by letting you use a higher Pe. Problem is, though, that at Jool you normally don't need (or want) to go deeper than about 190km, which is only 5% into the atmosphere. With such a shallow penetration, there's no significant difference in heat between 190km and 195km.

But maybe Jool is a special case. Does this work in 1.0.4 at Eve, Laythe, or returning to Kerbin?

[FlowerChild]

Remembering that the whole purpose of aerocapturing is just to save some fuel, how much did you end up saving afer deducting the costs of launching, docking, and carrying this structure to Jool? If I read the dV maps aright, the most aerocapture at Jool can save you is less than 2000m/s, rather less than the cost of launching something from Kerbin.

I find this to be an interesting point, but is the weight in fuel to ditch 2000 m/s really less than that of a heatshield for your average vessel? Like, the wiki lists the mass of the largest 3.75m heatshield to be 2.8 tons, while a T-400 fuel tank is at 2.2 tons. As a rough guestimate, let's consider those roughly equal (or throw in another T-100 tank on top to even things out more), and I really can't think of many vessels that would be big enough to warrant a 3.75m heatshield, yet wouldn't weigh enough that they could produce 2000 m/s deltaV off a T-400.

The way I'm looking at things, you'd have to transport that mass to Jool either way to make use of it, so it essentially all comes down to what is heavier: the fuel required for an equivalent burn or the shield for the aerobrake.

Edited June 30, 2015 by FlowerChild

[Korizan]

I have been building heat shields into my ships even before they where required.

1.0.4 Really didn't change very much for me, some small adjustments to PE but other then that, it was business as usual.

You don't really need to go nuts with the heat shields there is NO requirement to burn off all your speed on the first pass.

Aerobraking is all about capture, which is done on the first pass.

However it doesn't mean you won't have to make 1 or 2 more passes to burn off the rest of the speed, there is nothing wrong with this type of trajectory.

So I choose OTHER, stock parts but nothing extreme as it really isn't needed with the right trajectory and some patience.

[regex]

Aerobraking is all about capture

Aerocapture is all about capture, you aerobrake on subsequent passes.

However it doesn't mean you won't have to make 1 or 2 more passes to burn off the rest of the speed, there is nothing wrong with this type of trajectory.

This is very much true. Perhaps this new KSP just requires more careful approaches to space travel.

[Oxytropis]

I still aerobrake. just not as boldly now, The changes brought about another obstacle to overcome, another way to flirt with disaster. Losing is fun

[Mischief]

in the face of a hyperactive heat system.

Here's the thing though - where have you run into that? Other than a 90 degree orbital return from 400k after playing around with a huge pile of boosters under a return capsule with no heat shield I've had absolutely no issue with heating on any aerobreak anywhere.

Where are you aerobreaking and how that you're having issues with heat? Is it a desire to not have to use heat shields or radiators at all? Sincerely, I'm curious if I'm missing something or doing something wrong.

So to clarify my 'other' answer up above -

I use 100% heat, I travel interplanetary and aerobreak any time I can (Duna, Eve, Jool, Laythe) and don't have any big issues or use big heat shields or such. I just hit relatively high in the atmo and expect to use aerobreaking to spin down on 2 or 3 orbits - save on Duna, where it's too thin and you're just using it to save a bit of your deceleration burn fuel.

You put your stuff in sheltered bays on any aerobreaking designed ship or otherwise account in design for the need to shelter fragile parts for such an event but it's not a huge deal that I've run into.

Can you give me an example of when this has come up?

MOAR FUEL doesn't work on its own - you need MOAR ENGINE and MOAR BOOSTERS to lift it, which in turn requires MOAR FUEL.

[Geschosskopf]

The way I'm looking at things, you'd have to transport that mass to Jool either way to make use of it, so it essentially all comes down to what is heavier: the fuel required for an equivalent burn or the shield for the aerobrake.

But it's not just carrying the thing to Jool. You also have to get it off the ground. If you do as the original guy said and build it in orbit, then that's 1 or more extra launches worth of fuel, plus the fuel for rendezvous and docking. If you're in career mode, there's also the money for all that. And whether or not you worry about money, it takes more of your time, but the value you put on that and what you most enjoy doing with it is of course a matter of personal taste.

[FlowerChild]

But it's not just carrying the thing to Jool. You also have to get it off the ground. If you do as the original guy said and build it in orbit, then that's 1 or more extra launches worth of fuel, plus the fuel for rendezvous and docking. If you're in career mode, there's also the money for all that. And whether or not you worry about money, it takes more of your time, but the value you put on that and what you most enjoy doing with it is of course a matter of personal taste.

Yeah, I agree the multiple shields/orbital assembly would be an extreme investment that's probably not worth it in terms of the time you'd have to spend as a player. I was just wondering if there was something I was missing with regards to the efficiency of a single shield (which you could always encase in a fairing for the trip up) vs. the fuel required for an equivalent maneuver at destination.

I've also been fooling around with "folding" designs as of late due to the new aero which might present another alternative to full orbital assembly in cases where you require more than one shield. Stuff like this:

Which I've been using with my mod due to the low-tech solar panels in it being a real pain to use. It's a lot less time consuming to perform a few docking maneuvers to rearrange parts in a single vessel than to perform multiple intercepts with multiple vessels.

MOAR FUEL doesn't work on its own - you need MOAR ENGINE and MOAR BOOSTERS to lift it, which in turn requires MOAR FUEL.

You'd also need that to lift the shield as well too though, which is why I think it largely comes down to which winds up weighing more (for a single shield design anyways).

Edited June 30, 2015 by FlowerChild

[Geschosskopf]

Where are you aerobreaking and how that you're having issues with heat? Is it a desire to not have to use heat shields or radiators at all? Sincerely, I'm curious if I'm missing something or doing something wrong.

See the 1st post. There's a link in there to some tests I did. It's sort of deliberately a worst-case scenario, but it's useful for measurements.

Rockets, I agree, don't have that much of a problem. Fairings, heatshields, etc. But heat hates airplanes, even after their parts got a maxTemp bump.

[Aragosnat]

Depends on the craft and how comfortable I am doing atmosphere skimming with said craft. But, I try not to just to avoid having stuff rip off.

[Evanitis]

I find it difficult to get gravity assists. Usually they happen totally random to me.

Moons and planets are pretty predictable.

Other than that, the know-how is well documented.

[Mischief]

See the 1st post. There's a link in there to some tests I did. It's sort of deliberately a worst-case scenario, but it's useful for measurements.

Rockets, I agree, don't have that much of a problem. Fairings, heatshields, etc. But heat hates airplanes, even after their parts got a maxTemp bump.

So aerobreaking an aircraft at 5 or 6k m/s should be an issue. If you like to be able to do that that's cool, adjust it how you want to suit. I just would say the heating model isn't overdone, it's actually pretty gentle already. Just depends on the game experience you want.

I kinda like having heat be relevant but the cool thing about ksp is you can make it suit the play you want.