TCIS's Guide To Docking

[Chel]

Want to build a space station in orbit around a planet or moon, but you've resorted to building it in one go because you don't understand docking? Wanted to assemble a ground base on a planet or moon's surface? Want to dock two ships together, to transfer crew, fuel, or just to have some fun? Then this guide is for you!

What You Will Need

A controllable vessel (I say 'controllable' as you can also dock probes as well as Kerbal-controlled spacecraft).

A docking port (Can be any of the three sizes, but I will be using the standard 1.25m docking port. the 2.5m docking port is better for large vessels, and the 0.625m docking port is suited for small probes).

RCS thrusters and Monopropellant (used for docking with your target).

Knowledge of orbital rendezvous

Knowledge of velocity (i.e. speed)

A spacecraft (duh!)

Part 1: Building

If you, like most people use docking ports for, want to build a space station, you would simply launch the station 'core' (the main bit of the station, with everything docked around it), get it into orbit, and then leave it there. However, what about adding other things to it? This requires building a separate craft, getting it into orbit as well, and trying to catch up with the station. That seems difficult, but it's actually easy. For me, I've simply built a 'Crew Module/ Escape Pod' as my thing to dock in space. It's a cupola module, a Monopropellant tank, some RCS thrusters, some Sepatrons (used for the 'Escape Pod' bit. They should be enough to deorbit me and send me back to Kerbin), and of course, a docking port. That's only my example, but you can build whatever you want to add. Also, don't forget to add a launch vehicle, the thing that gets it up into space!

Example Of A Launch Vehicle

Part 2: Getting Into Orbit, And Rendezvousing

So you've built what you want to add to your station. You've put it on a rocket that'll hopefully get it into orbit. You're ready to launch. Here are a few tips: Firstly, wait until your target in orbit is near the KSC, as you don't want to get into orbit and have it halfway around the planet, do you? Secondly, wait until daylight! It is MUCH easier to dock in daylight then in the dark, as you can actually see what you're docking to!. With those things sorted, time to launch!

Once your rocket has taken off, simply get it into orbit, roughly at the same altitude as your target. However, DO NOT REMOVE THE MODULE FROM THE ROCKET ONCE ACHIEVING ORBIT! I say this, as you might get into orbit, but you probably won't be able to catch up with the station, having you just float around there forever. If you have any remaining fuel, wait until you and the target are on the same side of the planet (either both on the night-side or day-side, but day-side is preferable, as you can see your target easily). Set it as your target. On the 'Map' view, you will now see your target's orbit in green, instead of grey. There will also be a few nodes along the orbit path. There's one in particular: 'Closest Intersect'. This is where you and your target will be the closest to eachother, so you should set a manoeuvre node around that area, so you can make a burn to get really close. Once you've done the burn to intercept your target, then just timewarp around until you are nearing it. Then, once close to the target, stop timewarp. Now comes the actual docking.

Craft Preparing To Dock

Part 3: Velocity

Once you've closed the gap between your target, you will have to make your speed roughly the same as it. Otherwise, you could fly past the target, completely missing it, and having to do it all over again. Let's say that there are two ships, Ship A, and Ship B. Ship A is the one that you, Ship B, is trying to dock to. If Ship A is travelling at 2250m/s, and you, Ship B, are travelling at 2500m/s, then you are 250m/s faster, and will basically fly past Ship A. What you should do, is turn your craft around, so your engines are facing the way that you are going, and fire them. This is basically slowing down your craft in orbit. A 5m/s speed difference is ok, but you should probably have about 2m/s or even less. Once you are within 100m of your target, or in physical sight, you should prepare for docking. This is where RCS thrusters, patience, and a steady hand is important.

Part 4: Actually Docking

You've selected a docking port to attach to. Only now, you can separate your module from the rocket. Turn your ship around again, so that you're docking port is facing the other docking port. Then, at roughly 20m between you and your target, click the button below 'Staging'. This is called 'Docking Mode', and uses RCS thrusters for up/down, left/right, and backwards/forwards. The controls are as follows: LeftShift/LeftCtrl for forwards and backwards. A/D for left and right, W/S for up and down, and Q/E to roll left or right.

Lining Up To Dock...

Press 'Shift' to fire your RCS thrusters forward, but don't hold it down for long, unless you want to go forwards rapidly, and risk colliding with your target. As you approach the docking port, line your port up with the other one. Press 'Ctrl' if needed to fire your RCS thrusters the other way, to slow down, if need be, but you shouldn't really have to do this if you have been paying attention. Finally, at around 0.5m, the two docking ports should 'feel' eachother, and magnetically clamp. If they don't, then try again. Often the problem is that SAS is activated, so you should turn that off while the ports are connecting. Once they have connected, the camera will zoom out, and you've docked! To undock, right click the docking port that you attached to, and select 'Undock'.

...Docked!

Hope this long(ish) guide helped, TCIS.

 

Edited August 2, 2017 by The_Cat_In_Space