Launching from Kerbin and using it for gravity assist! :O

[JiWint]

I've heard of Juno a while ago,and it used earth as gravity assist.

And that's an incredible idea! But I just wonder,what orbit do I need to have kerbin for gravity assist after launching from it?

[Highlad]

Usually you will perform an assist with another plantet first (say eve) then swing back round for a Kerbin assist.

I think Scott Manley did something like this...

Edited December 27, 2013 by Highlad

[JiWint]

Usually you will perform an assist with another plantet first (say eve) then swing back round for a Kerbin assist.

I think Scott Manley did something like this...

-snap-

well,it's easy to do grav assist with eve and then kerbin,but my question was how to use kerbin for first gravity assist.

and if I would want to do everything with mods,I had planted all the flags on all the planets :|

[Deathsoul097]

You would have to be in a Kerbolar (Solar) orbit intersecting Kerbin's orbit, as you cant gain a gravity assist using the body you are in an orbit around.

[-ELF-]

Summarizing everything:

1) You cannot use Kerbin for gravity assist without leaving its SOI.

2) You can go to another planet, get gravity assist from it, get back to Kerbin and get the assist from it too.

P.S.

Juno was launched in some specific way:

- At launch it left Earth SOI

- It went behind the orbit of Mars

- It headed back and got the assist from Earth 2 years after launch

- Now it is heading for Jupiter

- Still another 2 years to go...

here is a picture:

[JiWint]

Well,I know how gravity assist works ._.

but I need the angles,or orbit altitude to get an actual intersect

[Superfluous J]

You want your orbit to be an exact fraction (or multiple) of Kerbin's orbit. Find out what Kerbin's year is on the Wiki, and make your orbit around Sun equal to 1/2 that, or 2x that. Then you'll go around the Sun once and Kerbin will go around twice (or vice versa) and you'll meet. Tweak your orbit once you're coming in like you would any other orbit. Note: You can do any fraction, like 3/2 or 2/3 or even 5/9 but you'll have to orbit that many times to get it to work. 1/2 and 2/1 are the easiest to to if you're just testing it to see the logic.

Finding your orbit's period is up to you, but here's a hint: all of the markings on your orbit tell you how much time it will take to get to them, including Maneuver nodes, which you can conveniently place anywhere on the orbit.

[SSSPutnik]

You don't need your orbit to be a multiple AFAIK?http://en.m.wikipedia.org/wiki/Gravity_assist

[Skorpychan]

I've managed to get a boost from Kerbin when coming back from the Mun. Ended up with an escape orbit despite a 20k periapsis. So, maybe a mun-kerbin approach. Or even just use the Mun; it can give a huge amount of delta-v with the right orbit.

[-ELF-]

SSSPutnik

Yes, to have gravity assist from any other body, you do not need multiples, but to take it from the planet you just left, it is the easiest way.