laythe aerobraking

[MilanFIN]

So I got my first succesful trip to Jool system with my strange setup. However I am for some some reason on polar orbit around Jool.

So my ship is on low fuel (250 liquid) and I would be able to get a Laythe encounter somehow, but not to waste fuel I'd like to try aerobraking as hard as possible to gain an low orbit.

[mellojoe]

First off: F5 and F9. Quicksave and Restore. Before you try anything crazy, hit F5 to save your gamestate. Then, when you go attempt an aerobrake, if it doesn't work, you can simply F9 and restore to that quicksave. I pretend this was a simulation run.

Secondly: Yes, it is entirely possible to aero-brake around Laythe. I'm going by memory, so please quicksave before you try it, but I think you want to aerobrake somewhere around 16km. I think 20km was too high, and maybe 15km was too low. The atmosphere starts around 44km, but is super thin. Don't forget you can even do multiple loops around as long as your PE stays in the atmosephere. And finally, you will need to do a burn at AP to bring your PE up out of the atmosphere. Getting it right though requires only enough fuel to raise your PE out of atmosphere, which isn't too too much.

[Dkmdlb]

For future reference, if you do a correction burn as soon as you get into the Jool SOI, you can make large inclination changes (including going from polar to equatorial) for not very much fuel - sometimes as little as a few dozen m/s delta v.

[Decent Weasel]

Secondly: Yes, it is entirely possible to aero-brake around Laythe. I'm going by memory, so please quicksave before you try it, but I think you want to aerobrake somewhere around 16km. I think 20km was too high, and maybe 15km was too low. The atmosphere starts around 44km, but is super thin. Don't forget you can even do multiple loops around as long as your PE stays in the atmosephere. And finally, you will need to do a burn at AP to bring your PE up out of the atmosphere. Getting it right though requires only enough fuel to raise your PE out of atmosphere, which isn't too too much.

Agreed. My braking occurs between 17.5 and 18.5 kilometers, but I'm coming straight out of a Hohmann from Kerbal, not Jool orbit, so I may be moving faster relative to Laythe, and you may want to opt for my upper bound so as not to shed too much velocity. And of course, double-check intercept after entering Laythe's SOI, as periapsis can shift by as much as fifteen kilometers when you switch over.

[MilanFIN]

thx for answers, at least I learned that I need to add more fuel to my ship next round

EDIT: btw how do I change this to answered?

[Technical Ben]

With enough quick save scumming (reloading abuse ), you can even do this:

That's what you get though for saving after you hit the aerobreaking and miss your destination. So save before, not after. Unless you also have a craft able to act as an emergency "boost".

[MrPopcup]

if your going to Land on laythe aero-brake @ 15km and under ( I know, not your case, but just for info ).

and if your going to orbit, Aero-brake @ 16 Km~ 18km. ( above you won't even make that decrease in speed. )

But all of it really depends on your speed, you may reach laythe and have low velocity so you aero-brake at higher altitudes than normal. the opposite is true..

[Specialist290]

EDIT: btw how do I change this to answered?

Edit your first post and select "Go Advanced." That should take you to a screen where you can change the tag to "Answered" from "Unanswered."

[Kulebron]

http://alterbaron.github.io/ksp_aerocalc/

Calculate the required aerobraking and go 150 metres higher, because your ship's drag is slightly more than 0.2.

The best maneuver is actually intercept laythe itself on the sun side of Jool. It rotates quickly, so tiny adjustments some 100 days before encounter let you get into its SOI and aerobrake right at Laythe. This aerobraking will be slower and less violent and risky than braking on Jool. And you don't need more fuel to get to Laythe.

If you use node editor plugin or MechJeb, you can even enter Laythe at an inclination aligned with islands, to ease landing on the ground.

Edited September 27, 2013 by Kulebron