How to dock large space station sections

[Marklar1138]

I managed to get the main module of my first space station in orbit around kerbal. I then created a large arm to hold several solar panels. The problem is the while using SAS to align and approach I use forward thrust to vector into alignment. But then I have to rotate the section around to be able to retro burn to slow the closing speed. The time it takes to rotate the section to burn prograde or retrograde is making it almost impossible to align and set a proper speed to close on it.
Is there something I am missing? How do you get space station pieces up and docked to a station? I also noticed with the auto-controller (instead of a pod) some of the markers in the ball are absent.

[Vanamonde]

The problem you are describing is not clear to me. I would suggest either reducing the closing speed before you start reorienting, or putting more thrusters on the craft to reorient more quickly once you are there. Other than that, it seems like just a matter of practice. 

[adsii1970]

I use a probe core on a disposable and detachable section of the part I am adding to the station. I also have a crazy amount of monopropellant and a lot of RCS thrusters to cover every possible direction one could ever need to nudge a station. I really do not have any screen shots of me assembling a station in orbit because I never think to take any at the time. But on the disposable and detachable section of the module, I have the larger monopropellant rockets to handle larger nudges as needed.

The disposable and detachable section also has a third stage rocket engine mounted on it facing away from the large docking ring and two smaller rocket engines on "pods" to the side that are on the ring side to act as braking rockets to keep me from moving the part too fast. Oh, and I use the action group keys a lot. Did I stress a lot enough? The first few stations I put together like this were sheer disasters. I had parts floating in a ring of debris all around Kerbin!

[king of nowhere]

17 hours ago, Marklar1138 said:

I managed to get the main module of my first space station in orbit around kerbal. I then created a large arm to hold several solar panels. The problem is the while using SAS to align and approach I use forward thrust to vector into alignment. But then I have to rotate the section around to be able to retro burn to slow the closing speed. The time it takes to rotate the section to burn prograde or retrograde is making it almost impossible to align and set a proper speed to close on it.
Is there something I am missing? How do you get space station pieces up and docked to a station? I also noticed with the auto-controller (instead of a pod) some of the markers in the ball are absent.

this is exactly the kind of problem for which an rcs would help. but, assuming you don't want to use an rcs, it's still not so difficult.

First, from some distance (say, 100 meters) burn toward the docking port. then immediately turn around. Stop your station part at a few meters from the station. the closer, the better; you want to make drifting negligible. make your speed 0.0 meters.

at this point, you turn the arm around again, carefully align the docking ports, and then you push. slowly. 0.2 m/s, 0.3 at most.

[Maria Sirona]

The relative speed has to be lower than 2 m/s

[DeadJohn]

On 5/16/2022 at 2:04 PM, Marklar1138 said:

...I use forward thrust to vector into alignment. But then I have to rotate the section around to be able to retro burn to slow the closing speed. The time it takes to rotate the section to burn prograde or retrograde is making it almost impossible to align and set a proper speed to close on it.
Is there something I am missing?...

Use RCS thrusters, not main engines, when you are close to docking. It's possible to dock with just an engine but it takes a lot of practice.

 

On 5/17/2022 at 7:27 AM, king of nowhere said:

How do you get space station pieces up and docked to a station?

Sometimes I put RCS thrusters and a reaction wheel on my upper stage, use that to handle the docking, then disconnect and deorbit the upper stage. Other times I'll keep an "RCS tugboat" docked to the station to grab and manipulate incoming pieces when they get near my station.

An example of docking when I have good RCS on both station parts: I launch the 1st station part and make sure that it has a reaction wheel or balanced RCS thrusters, a pilot or probe able to use SAS target-hold, and docking ports. Launch the 2nd part, maneuver to an intercept, get to around 100 meters, use the engine or RCS to bring #2 to a stop relative to #1.

Make sure that #1's target is #2, and #2's target is #1. Right click the relevant docking port on #1 and #2 to "control from here". Use target-hold SAS mode to keep those ports aimed at each other. Then use RCS from either #1 or #2 to dock.

If you are in SAS target-hold mode then press "]" to change ships, the ship that you just left will remember target-hold. You can therefore have both docking ports on 2 different station pieces stay aimed at each other with target-hold as you gently maneuver closer with RCS. That for me is the key to easy-mode docking. If you press "]" yet again to go back to the first ship its SAS will default to position hold and you'll need to turn on target-hold again.

Remember to click the navball if needed to toggle between its orbital mode and relative/docking mode.

Docking can be overwhelming for new players. Practice in sandbox mode. Build a relatively simple docking practice satellite, cheat 2 of them to an orbital rendezvous using alt-f12, then dock, undock, redock, etc.

On 5/16/2022 at 2:04 PM, Marklar1138 said:

I also noticed with the auto-controller (instead of a pod) some of the markers in the ball are absent.

Early probe cores can have limited SAS modes. The HECS2 higher up in the tech tree has every SAS mode, plus a strong reaction wheel and big battery. Right click a probe core in VAB to see its available SAS modes.