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How to use Tylo to get an assist into Jool orbit?


Mad Rocket Scientist
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Hello!  I'm trying to get a gravity assist to get into Jool orbit.  I've never done this before, and I'd be happy to hear any tips! 

Here's what it looks like:
7D50p8F.png

These are my primary questions:

  1. How can I see whether I will be in orbit after I've exited Tylo's SOI, before I've entered it?
  2. How can I figure out where I need to enter Tylo's SOI, and at what angle, to be captured into orbit?

I can easily provide more info if it's needed.

Thanks a lot!

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If you change that setting I mentioned, you should be able to see the resulting orbit.  The trajectory shown in the OP does not look like it will result in a good capture.  As I indicated, I try for a trajectory that just touches the circle of Tylo's orbit in one place and then adjust my trajectory in and out a bit using the maneuver node handles until I have an encounter and then adjust that until I have a good capture.  I like to do this about halfway between Kerbin and Jool.

This is five Tylo gravity captures - one for each of the original ships in my KRRAKC Jool flotilla.  All but the middle one are pretty much encountering Tylo just at the tangent to its orbit.  And the middle one, which cuts across a bit, results in the most eccentric capture.  It is definitely a bit fiddly.  But very satisfying to get.

edit: Actually, the fourth one cuts across quite sharply as well.  Anyway - once you can see the resulting orbit line - red in this case - you can adjust it until you have a good capture.

 

Hope this helps.

Happy landings!

Edited by Starhawk
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Put a maneuver node at Tylos PE and it should show the exit.

Your going to want to turn the other way.  They way you are going now would increase velocity.  You are going to add tylo velocity and you want to subtract it and change your angle

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2 hours ago, Mad Rocket Scientist said:
  1. How can I see whether I will be in orbit after I've exited Tylo's SOI, before I've entered it?

There is a setting in the settings.cfg file called CONIC_PATCH_LIMIT.  I think the default setting is three which is nowhere near enough at Jool.  Try changing the value to 5.  That seems to work well for me.  This will allow you to see future trajectories through several SOI changes.

Where are you?  The farther away you are, the less expensive the course correction.  I try to set up my Jool trajectory so that it's just tangential to Tylo's orbit and then I adjust using a combo of prograde/retrograde and radial/anti-radial until I have the Tylo encounter and further adjust the same way until the resultant Jool orbit is something I can live with.  Using the mouse scroll wheel for fine adjustments to the maneuver nodes makes all the difference for me.

Happy landings!

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33 minutes ago, Nich said:

Put a maneuver node at Tylos PE and it should show the exit.

Your going to want to turn the other way.  They way you are going now would increase velocity.  You are going to add tylo velocity and you want to subtract it and change your angle

Thanks! 

 

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I've never tried approaching Tylo after going around Jool. It strikes me that it would be hard to get it to work well (really difficult to get the right angle).

This is my standard Tylo assist:

Spoiler

EJ8rHJo.png

This time I'm heading for Pol. Got a very lucky alignment.

The 231 m/s burn is because I left it horribly late to get a Jool encounter, so the interplanetary transfer was abysmal. The two other nodes are 6.8 m/s correction to hit Pol, and 511 m/s capture burn at Pol (but I hope to do significantly better - it's simply too jittery to plan).

Oh and Tylo Periapsis is about 300 km here. Anything in the 200-400 km range gets you well and truly captured in the Jool system.

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15 minutes ago, Starhawk said:

There is a setting in the settings.cfg file called CONIC_PATCH_LIMIT.  I think the default setting is three which is nowhere near enough at Jool.  Try changingthe value to 5.  That seems to work well for me.  This will allow you to see future trajectories through several SOI changes.

Very useful setting, thanks!

15 minutes ago, Starhawk said:

Where are you?  The farther away you are, the less expensive the course correction.  I try to set up my Jool trajectory so that it's just tangential to Tylo's orbit and then I adjust using a combo of prograde/retrograde and radial/anti-radial until I have the Tylo encounter and further adjust the same way until the resultant Jool orbit is something I can live with.  Using the mouse scroll wheel for fine adjustments to the maneuver nodes makes all the difference for me.

Happy landings!

I've completed the burn, it only was about 20 m/s.  I'll do another course correction inside Jool SOI too.

 

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7 minutes ago, Mad Rocket Scientist said:

Very useful setting, thanks!

I've completed the burn, it only was about 20 m/s.  I'll do another course correction inside Jool SOI too.

Did you get a good capture around Jool?

Happy landings!

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To get the maximum braking affect you need to encounter Tylo moving close to parallel to it and leave it perpendicular.

i.e. if you are approaching Jool from its 6 o'clock you want to aim to encounter Tylo (or another moon) at about 3 or 9 o'clock.

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On 3/16/2016 at 6:10 PM, tomf said:

To get the maximum braking affect you need to encounter Tylo moving close to parallel to it and leave it perpendicular.

i.e. if you are approaching Jool from its 6 o'clock you want to aim to encounter Tylo (or another moon) at about 3 or 9 o'clock.

adding my two sense to this: also try to aim as close to the surface of Tylo as possible, the lower you are, the stronger the gravity and better the braking.
one time I had a vessel actually break a solar panel off by scraping it along the surface as I slingshot around it.

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Op, your original picture shows you actually getting a gravity assist to leave jool's SOI(ie, leave it faster with more velocity), if I interpret it correctly.

You'd want to pass on the other side of Tylo to get it to assist you in staying in Jools SOI.

If your orbit bends in towards direction tylo is moving, then your velocity will be higher leaving Tylo's SOI vs when you entered it. If it bends away from the direction tylo is moving, then your velocity is reduced by tylo... if I understand it correctly.

Anyway... Laythe also works nicely, and you can even set up a laythe gravity capture that involves passing through the upper part of Laythe's atmosphere, so that you can do some aerobraking too to get a less eccentric capture... obviously adjust the depth that you go into laythe's atmosphere according to your craft's capabilities.

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On 4/5/2016 at 5:53 AM, KerikBalm said:

Op, your original picture shows you actually getting a gravity assist to leave jool's SOI(ie, leave it faster with more velocity), if I interpret it correctly.

You'd want to pass on the other side of Tylo to get it to assist you in staying in Jools SOI.

If your orbit bends in towards direction tylo is moving, then your velocity will be higher leaving Tylo's SOI vs when you entered it. If it bends away from the direction tylo is moving, then your velocity is reduced by tylo... if I understand it correctly.

Anyway... Laythe also works nicely, and you can even set up a laythe gravity capture that involves passing through the upper part of Laythe's atmosphere, so that you can do some aerobraking too to get a less eccentric capture... obviously adjust the depth that you go into laythe's atmosphere according to your craft's capabilities.

Yes, I had it wrong when I took that screenshot.  I've changed it since then, so it's going the other way.  Thanks, though!

 

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