Aerobraking at Jool, how to do

[Farex]

Greetings,

last night I was doing a Joolmission, first time since 1.0 to be honest.

And whenever I entered the atmosphere of jool, my craft got ripped apart, literally. Put the periapsis at 199.xxx and after a few seconds it just goes BOOM.

Yes, heatshields were used.

I knew that Eve is really harsh now but does this make the Joolsystem not aerobrakable anymore?

Edited September 28, 2015 by Farex

[SpaceplaneAddict]

Yea, I heard somewhere that Jool is not impossible to aerocapture at. It would be better if you tried to intercept Laythe and aerocapture there. You'll have an easier time, and a better orbit. I think.

[Red Iron Crown]

It's more difficult than Eve because the craft is carrying much more velocity.

Better to use a Tylo slingshot for capture, no worries about overheating and you can fine tune it to get close to your eventual target.

[Streetwind]

The atmospheres of some of the other planets were not quite as well tuned for the new aerodynamics and heat simulation in 1.0 as Kerbin was, especially since these systems changed dramatically several times over the four patches that followed. Right now, Jool's atmosphere (among others) produces way too much heat way too early, resulting in parts exploding from skin temperature spikes - even heat shields cannot ablate fast enough to mitigate the high influx of thermal energy into a skin with nearly no thermal mass to receive it with.

This is being looked at for 1.1, but until then, you're better off finding ways to brake out of interplanetary transfers than aerobraking, as Red Iron Crown suggested.

[cantab]

Use the heatproof cheat or do a gravitational capture. To set up a gravitational capture place a manoeuvre on your way to Jool, and trade prograde/retrograde and radial/antiradial which lets you adjust your time of arrival at Jool while keeping your Jool periapsis the same. Cross the orbit of Tylo or Laythe when they're in the right place and there's your encounter for a potential capture. I always advise Precise Node for any gravity assist work.

[xebx]

Laythe aerobraking is the way to go, your velocity is lower (not the 9000 m/s). Gravitational capture is nice too, a mix of it and you can save lot of deltaV (in the end that's what happen when you aerobrake at laythe)

[OhioBob]

Aerocapture at Jool is theoretically possible but very tricky. I've done it successfully, but you need a properly designed craft and you have to hit the correct periapsis altitude within a couple hundred meters. Being off just a little bit and you'll explode. The spacecraft needs a low ballistic coefficient, i.e. low mass per unit area of heat shield. I think it's virtually impossible to aerocapture a large massive vehicle, but it can be done with a small probe equipped with an oversized heat shield, such as a 2.5m shield on a small 1.25m probe. Finding the correct periapsis altitude will likely require experimentation, which means it will take a save and several reloads until you get it right. For the one time I did it successfully, the conditions were: spacecraft mass at entry = 2915 kg, heat shield size = 2.5m, entry velocity = 9783 m/s, and periapsis altitude = 196,200 m ±200 m. It's probably easier just to use a different method as described above by others.

[Farex]

@cantab

No cheating

@Topic

Well then, off we go to get a flyby with tylo and laythe. Never done it this complicated since 0.22 - always exciting new stuff in KSP, yay!

This means no lazyass direct aerocapture by jool like in the good old times. hmmmmm.

[Guest]

Good info in this thread. Jool aerocapture is something I'd been wanting to experiment in 1.04. So far, everything I've tried has failed with explosiveness. Setting up the gravity assists I personally find to be tedious and boring sometimes unless I'm just in the mood to experiment with them. Most of the time for most of my missions I'd just rather use Jool for my brake to get me into position for the target moon. I like the idea of making Jool similar to Jupiter as far as how the aero-heating model should work, but the way things are now from what little I've read about Jupiter, it seems that Jool aero-capture is way to difficult and the atmospheric model needs to be tweaked. That being said, I personally wouldn't consider it cheating or lazy if I have to adjust difficulty settings to offset a broken or flawed game mechanic.

[JedTech]

It's a good thing they made it harder to aerobreak at other planets. People were spending way too much time away from Kerbin.

[Kryxal]

I still say aerobreaking at Jool is really easy, it's aeroBRAKING that's difficult...

[Farex]

Oh well excuse me for this typo. Fixed it.

[xebx]

And about Gravity assist for brake/capture or accelerate :

[Farex]

Thank you all for your tips, used tylo flyby, then val and a small burn around jool. Worked.