Insane DeltaV burns (3-4km/s) to Match planes with Joolian Moons

[LapraLapso]

Hello. So I usually use MechJeb2 to do my manuevers as I'm still learning, and I also play in Sandbox, but I always hate going to Jool because of the INSANE DeltaV required to match planes (change inclination) with a moon such as Laythe or Pol. I really hate it. When I go into Jool, circularize, and set a moon as a target, and check my Ascending or Descending nodes, it'll ALWAYS say any number above 150°. my orbits are almost the same inclination wise to the moons but it uses so much Dv to do a hohmann transfer to them. Please dont hate on me for being dumb. I've only been playing for 54 hours.

[Vanamonde]

I'm not sure what you're describing, but it sounds like you might be coming around the wrong side of Jool and facing head-on collisions with the moons.  You want to approach a little to the right of the planet rather than the left. 

[MaxxQ]

12 minutes ago, Vanamonde said:

I'm not sure what you're describing, but it sounds like you might be coming around the wrong side of Jool and facing head-on collisions with the moons.  You want to approach a little to the right of the planet rather than the left. 

Yeah... first thing I thought (when I saw the title of the thread) was that he was on a retrograde orbit relative to the moons.

Edit: @LapraLapso... If you're using MJ, I can't understand how you're ending up in retrograde orbits, if that's what's actually happening.  Are you using MJ to get to Jool to begin with?  If so, then once you're outside of Kerbin's SOI, you should try fine tuning your approach.  There's an option for this in the MJ maneuver planner.  Set the desired distance to something a bit farther out than where you end up intending to be once your Jool orbit is circularized (i.e.- If you intend a 600km orbit, best fine tune to 1000km, as it's not entirely accurate).  This will only cost you a very few m/s DV, and once you reach a Jool encounter, you can adjust for your final Jool orbit.

If you look down on Jool in map view from directly overhead, your ship should be orbiting counterclockwise, the same direction the moons are orbiting.

Edited September 3, 2017 by MaxxQ

[LapraLapso]

Hmm. I think that could be it! I'll try it out guys! Will let you know if it still doesnt work

Edited September 3, 2017 by LapraLapso

[invision]

i dont bother with inclination with jools moons, just get any part of your orbit line to touch the moons orbit line and time warp until you encounter it.

 

[Gargamel]

15 minutes ago, MaxxQ said:

 

Edit: @LapraLapso... If you're using MJ, I can't understand how you're ending up in retrograde orbits, if that's what's actually happening.  Are you using MJ to get to Jool to begin with?  If so, then once you're outside of Kerbin's SOI, you should try fine tuning your approach.  There's an option for this in the MJ maneuver planner.  Set the desired distance to something a bit farther out than where you end up intending to be once your Jool orbit is circularized (i.e.- If you intend a 600km orbit, best fine tune to 1000km, as it's not entirely accurate).  This will only cost you a very few m/s DV, and once you reach a Jool encounter, you can adjust for your final Jool orbit.

If you look down on Jool in map view from directly overhead, your ship should be orbiting counterclockwise, the same direction the moons are orbiting.

MJ doesn't set your orbit per se, you still have to tell it what orbit to take.   So if you just tell it to plan an encounter, and after entering the SOI, you just blindly circularize, you can easily end up in a variety of orbits.  I usually have to set my inclination, or at least be aware of it, right after entering the SOI.   Entering a retrograde orbit is very easy to do with MJ, but it's also very easy to fix. 

[LapraLapso]

I'll try it out guys, will let you know what happens. @MaxxQ

[StrandedonEarth]

The best time to change inclination, or reverse a retrograde orbit, is as far away from the primary as you can get, when your vessel is moving slowest. The lower you are, the faster you move, so hitting Laythe retrograde is a very fast encounter indeed

[LapraLapso]

Well it turns out it did work! Thank you guys for solving a problem I thought I could never solve haha!

[Vanamonde]

Yay! 

Also, moved to Gameplay questions. 

[MaxxQ]

51 minutes ago, LapraLapso said:

Well it turns out it did work! Thank you guys for solving a problem I thought I could never solve haha!

Glad I could be of some help.