How can I fix a crooked oblong orbit to match a spherical orbit?

[Hootenanny]

Alright, here's the breakdown of the situation my friends:

Items: two-module space station, third-module/rocket.

1. I'm trying to dock a third module to my space station. So far I'm 0/3. 2 attempts are floating in orbit with no fuel, my last attempt is a in long kind of narrow oval orbit with fuel enough for 2, maybe 3 maneuvers.

2. My two-part space station is in a oval-like orbit as well. I've got one maneuver's worth of fuel left in it. Right now it's Ap is about 102km and it's Per is 240km.

3. My two-part space station was my very first and only dock. I'm starting to realize it was just dumb luck and it took me like an hour of playing with the maneuvers controls to finally get it to .2km. The two orbits couldn't of been more different from each other and now I'm really surprised I did it at all.

4. I've never successfully turned a crooked oval orbit into a spherical one match the plane of what I'm trying to rendezvous with. I keep tinkering and tinkering and I'm getting nowhere. it's start to drive me nuts.

All tutorials I look at involve getting into a similar orbit to the object you want to meet immediately after launch. I've only found help for the best of situations. I need help for the worst of situations. Again, I don't know how I even did this the first time, I thought I understood what I was doing but the more I try the more confused I feel. I need HELP!

[ElWanderer]

The easiest way to make an orbit circular is to burn prograde at apoapsis (bringing the periapsis up until it's equal) or retrograde at periapsis (pushing the apoapsis down). Circularising elsewhere in the orbit would mean adding a radial in or radial out component to the burn, usually means lots of fiddling with the manoeuvre node. From the sounds of it, you may benefit from practising that, so you have more of a feel of how burns change orbits. Rendezvous will not be easy without that knowledge, unless you are prepared to spend more delta-v to work with perfectly circular orbits only.

For rendezvous, I would always try to match inclination first. Then get the orbits to intersect. Then plot a node at one of the intersects (you usually end up with two) and see how the closest approach markers change. The aim is to get a phasing orbit, whereby the difference in orbital periods is equal to the difference in arrival times at the intersect. As it is usually put: if you are ahead of the target you want a larger orbit so that you go slower and the target catches up. If you are behind the target, you want a smaller orbit (though avoid dipping into the atmosphere) so that your orbit is quicker and you catch up.

[RocketPropelledGiraffe]

Welcome Hootenanny,

it seems you have your work cut out for you. Learning to dock and rendez-vous is never easy, and your situation is certainly not ideal.

First a question for you:
Do you know what to do to get matching orbits in theory and you are having trouble doing the actual burns correctly?
Or do you need some help to learn the basic ideas of rendez-vous in space?

For now, I'll assume the latter. :)
To get your two objects to matching orbits, you have to adjust the inclination, periaps and apoaps, and the relative argument of periaps to match.

Inclination is the relative angle between the planes of both orbits - they intersect along one common line. If you set your target space station as target in map mode the line will be displayed, along with two markers "ascending node" and "descending node". It will also tell you the relative angle. You can match the angles by doing a normal or antinormal burn in one of these nodes. You have to do the maneuver in those points, otherwise you will never get matched inclination.

Periaps and apoaps are the points closest and furthest to the parent body in orbit. You can adjust your periapsis by burning prograde or retrograde at apoapsis, and you can similarly change your apoapsis when burning at periaps.

Argument of periapsis (AoP) is the position of the periapsis points of your ship and your target relative to each other. For example, if you imagine the target orbit as (stretched) clock face with the periapsis at 12 and the periapsis of your spaceship at 3, then the relative AoP is -90°. To match the AoP you want to burn radial or antiradial at the intersection of both orbits.
If you are in a circular orbit, this value is meaningless because periaps and apoaps are the same. That's why it is easier to dock in circular orbits.

If this is new information for you, then I would advice to turn on infinite fuel and do some tests, until you get a feeling for the effects that the indicated maneuvers have on your orbit. These are the basics, and doing as described is usually not the most efficient way, but it will get you there and help to understand what the maneuvers do.

You can combine several burns into one, there are tricks to make inclination changes cheaper, and so on. Anyway, you should worry about efficiency as a second step.