Correction Burn

[Rylant]

Hey All,

So I am progressing along fairly well in my second attempt at a career play through.  My first attempt I gave up after Duna as I found it really hard.  I have enjoyed the second play through and I have been to Duna and back and just going to go to Eve and hopefully land on Gilly.  I have found a few sites to be instrumental in planning Delta V and Launch windows.

So my question is.  I am able to play around and get an encounter with Eve.  I notoriously waste a ton of Delta V in going places in that I am just not good at being perfect with these things, but can usually make it work if I pack a few extra Delta V.  My latest return attempt to Eve / Gilly will be in a rocket with just over 8500 Delta V.

In my firsts attempt to get an encounter with Eve, I just happened to come in well where the correction for inclination with Gilly was pretty minor.  I then noticed that I happened to bring along a Pilot and 2 Engineers, instead of a Pilot, Engineer and a Scientist...  So, that was kind of stupid of me LOL.  

So I reverted the launch and Loaded up Jeb, Bob and Bill and launched again... I was able to get an encounter with Eve, but this one took a little longer and I had to fight with my Maneuver node a bit.  However, I am coming in at a really goofy inclination to Gilly which is going to be nasty to correct  if I wait until I reach Eve.

I have looked and most say to do a correction burn about halfway to the destination playing with the Normal / Anti Normal nodes to do a slight correction burn and it usually takes a relatively small amount of Delta V to correct this way.  My encounter with Eve is in around 80 days, so I wait until day 40 or so and try to play with the Nodes, but I can't seem to correct the inclination.  I can change it a couple of degrees, but nothing crazy.  I can also get my Apoapsis much closer to Eve, but can't seem to correct the inclination well.  I have looked online and have seen a few things, but nothing really specific.

If anybody has anything they could offer, I would love to hear your suggestions.  I am sure I am just doing something silly.

Thanks,

Rylant

[Guest]

It doesn’t have to be half way, in fact usually the further away you are the less dV you need to do your correction. If I’m going to Eve from Kerbin, I’ll usually do the transfer burn when I leave Kerbin’s SOI (sphere of influence). (I may need another closer to the target as well to fine tune).

As for changing the encounter path, sometimes the issue isn’t directly inclination. I usually plot a node then just change different handles noting the distance of the Pe next to the target planet / or trajectory. Sometimes you might need some Radial In with some Retrograde or prograde with some anti normal for example. Sometimes I mess it up and have to delete the node and start again. 

Once you get confident you can then do it without nodes using RCS (and H/N keys), again doing further away results in huge changes for a tiny amount of monopropellant use.

Once you go beyond confidence and into arrogance, you can then do things like aero brake in Eve’s atmosphere in such a way that it adjusts the trajectory to what you want. Or use a moon to do similar. As with everything  in the game it comes with skill & experience.

[king of nowhere]

as for going to Gilly, though, you do not need to have a good inclination, nor you need to match inclination with Gilly. The best way to reach Gilly is to park around Eve in a highly elliptic orbit, then from close to your apoapsis you aim for where Gilly will be, and you get there. your orbit is very slow at apoapsis, so you can generally make a burn with a large radial/normal component and get away with it, and it's cheaper than trying to match inclination. I can generally do it with a few hundred m/s, with an extra 400 m/s for capture.

Some examples here

the orbital nodes are really close to Eve, so i'd have to spend a fortune to change inclination. but a slight 120 m/s burn did the trick of setting me on intercept course.

ù

here it's even cheaper, just 66 m/s

this time i even saved the components of the burn, you can see it's a complex tridimensional one

And here is a return trip to rejoin the mothership, again it displays the burn components. I could have made it cheaper if i waited the next orbit, but i have a life support mod and i didn't have enough food to wait.

 

So, those trajectories are complicated, especially for someone who has problems with regular planetary transfers. How do you find them?

Set Gilly as a target once in Eve orbit. You will see the ascending/descending nodes. You do not want to make a manuever there, as they are generally very close to eve and require a very expensive burn. What you want is to intercept Gilly's orbit with one of them.

Plan your manuever node in some point high in your orbit. Doesn't matter exactly where, but it must be far from Eve. Then try to move one of your inclination nodes on top of Gilly's orbit. Try first with normal/antinormal component, you should get there. once you reahc your intercept, the game will provide a close approach marker for you.

Of course, you won't have a Gilly's intercept yet. You are merely crossing its orbit. But the close approach marker will let you know when Gilly will be there. So now you have to change your flight time to make sure you also pass in that spot at the same time as Gilly. A prograde burn will make for a higher Eve apoapsis and will make you lose time, if Gilly pass behind you. A retrograde will make you arrive there faster, if you need to catch up to Gilly instead. radial burns will change where you intercept Gilly's orbit. If you can't find a good solution because Gilly is too distant, try the next orbit.

During those manuevers, you will move around the planar nodes, and you will lose the close approach marker. Fear not! Just change your normal component until you put your planar node back where it must be, on top of Gilly's orbit, and the close approach will appear again.

[Rylant]

Thank you both. Super helpful. 
 

Rylant