Docking
Is it impossible?
No.
It's necessary
(If you want to progress...)
When docking, the main thing that you need to bear in mind is what is known as
orbital speed (how fast you're going around in that circle). Everything in different orbit sizes is moving at a different speed.
That also goes for the speeds at Apoapsis and Periapsis. Just cos you're at the same height orbitally, if the other side of the orbit is different, then your speeds will still be different.
Where as everything in the same orbit is moving at the exact same speed.
So, Imagine we're like this. one section that we're controlling at a slightly lower orbit than than where we want to dock.
Press on the destination section...
And press
Set As Target.
And the screen should look roughly like this. Notice, there's no transfer window, just a direct line (The
closest approach line) from you to the closest you'll get to that object in this particular orbit cycle you're on. See how it's roughly diagonal as well? That's bad.
To alter that, you need to time warp so your craft orbits around the Earth along with your target. Now, because they're moving at different speeds, one will catch up to the other. What will happen before that is the closest approach line will line up straight and stop moving. How long that takes depends on the difference in orbit sizes. If they're 150 odd Km apart, then the speed difference is huge and one will catch the other a lot quicker. If the orbits are very close together (like, 15-20km) then the orbital speed difference is a lot less and it can take a while to get them to line up properly.
Anyway, eventually this will happen...
At the bottom left corner of the orbit, there is a very short line. That is the closest approach line from earlier, but as close as the orbits allow, and it will be static as you orbit.
If you zoom in there, it'll look like this...
Now, for a tiny bit more orbiting. What needs to happen now is keep going around until the orbit
before you actually catch up to the target section.
Then, once in that rotation and at the exact opposite side of the orbit to the Closest Approach line, burn prograde
slowly until the orbits meet.
The Closest Approach line will move again. Don't worry about that, let it move until the orbits meet and overlap slightly. The Approach line will then jump to either one of the overlap points and become very small.
Zoom in...
And your closest approach is now in metres rather than km.
Throttle down even more and burn very gently prograde and watch that number shrink...
To distance a few hundred metres or so. Less than 500m is good, between 100-200m is better. Too far and you may miss completely. Too close, and if you burn to0 late for slow down you could risk just crashing straight into your target.
If the number starts getting bigger, then you're burning in the wrong direction. Switch to retrograde and try again.
The earlier you get this sorted, the less Dv it costs.
Then, once you've got that nice and close, now time for more orbiting. It never goes straight in that first time, so don't panic if it misses by miles that first rotation.
On the second rotation, they will get very close and start roughly flying close. Press on your craft and select
Follow to make this part easier.
Zoom right in so you can see both craft and sack the time warp if you're still doing it.
It should look roughly like this.
Now, we're close, but we're facing in the wrong direction for the speed matching burn. Rotate the craft so that the incoming object is approaching from the tail end.
Now, when it comes in relative to you, you can burn away, thus slowing your approach down.
Keep zooming in as they get closer and closer. Then, switch to normal view and zoom out so you can just about see your craft as a dot. Eventually, a second dot will appear moving in.
Hard to spot? Zoom in a little bit more as it approaches. It will pass 177m away from you so you can afford not to worry yet
Like this. Once you're pretty close, but before it passes, you burn hard away from it to equalise your closing speeds.
Remember to bear in mind how much speed you need to catch up when doing this. I've come from pretty close with a light rocket armed with a pokey engine so a very short stab of throttle was enough to sort it.
If however you're coming up from 31km to 150km direct and you've only got 4 Ions decelerating your 1500t 3rd stage, then you're gonna be in for a shocker as it screams past you laughing.
What you're actually doing is making your orbit exactly the same as his, at the same place as he is, so you fall around the Earth at the same speed but are static relative to each other.
Also, ignore the direction arrow and the speed gauge. They are relative to the body you are orbiting, not the target you've selected. All of this is done by dead reckoning and judgement.
Now, to make contact. This is pretty easy with RCS, as you just press an arrow and the craft moves in that direction. I've gone full hard core (cos I forgot to fit it with RCS...) and am docking old school with main engine inputs.
With a wee bit of arsing about, you get your docking ports as close as possible. They're 'magnetic' and will not only lock as they pass but have a slight attraction to each other as well so will pull you in if you are close enough.
And docked. You can now transfer fuel an whatever you wish to do with both of them. They are now one ship for all intents and purposes until you separate them.