ArmchairGravy's Guide to Docking with Pictures and Fairly Small Words

[ArmchairGravy]

I was like you, once. Hated docking. Tried to dock, and failed miserably. Tried again, failed even worse. However, I slowly, painfully learned the secrets that not only make docking possible, but actually fairly easy once you've done it a few times. Here I share these secrets with you, the person who wants to learn how to dock without needing PTSD treatment afterward.

I will break "docking" in two parts: rendezvous and the final docking sequence. Rendezvous is 90% of docking. I use no special mods, and don't even use docking mode.

Prerequisites (Stuff you have to know before even thinking about trying to dock)

1. Know your translation keys. Default mapping is i=forward, k=back, h=up, n=down, j=left, l=right. If you are not sure, go into Settings-->Controls and make sure you know what your translation keys are!

2. You must be able to get a reasonably circular equatorial orbit. 1 or 2 km difference between apoapsis and periapsis is reasonable. If you can't do this, practice making circular orbits until you can. You want as "flat" (non-inclined) of an orbit as you can manage as well.

3. You must be able to "burp" your engines. Those quick 1/2 second burns will be needed in the latter part of a rendezvous as you drop your speed from 1m/s to .5m/s.

4. Patience! Rendezvous and docking takes time and is easy to mess up. Get yourself mentally prepared for a bit of an ordeal.

OK, let's get to it!

First, if you don't have a flag planted on Kerbin somewhere, run someone out into the field by the launchpad and plant one. Switching to this will allow you to speed time up faster than the 50x limit of Low Kerbin Orbit (LKO), which is where we'll be operating.

Now, head into the VAB and build a craft that's easy to dock. Like so:

Things to note: You are looking at the back of the vessel and facing forward. Put a light on this side so you can tell when you are facing forward. Put lights on the sides to light up the docking ring so you know where it is.

RCS Placement:

Turn on angle snap (the hexagon at the bottom left) and two-symmetry for your RCS placement. Place thruster blocks and linear thrusters at the top and bottom of the craft. This gives you control of up/down, forward/back, and left/right:

Once you have your docking craft ready to go, launch that puppy! I already have a space station in an 80km orbit to dock with. If you don't you'll need to launch two docking craft. Place the first one you launch into the 80km orbit. When you launch the second one, check to see where the first one is. If the first craft is ahead of the second craft, place the second craft into a 75km orbit. If the first craft is behind the second craft, place the second craft into an 85km orbit. Remember: Things in lower orbits will catch up to things in higher orbits! Also, you want the orbits of the two craft to be fairly close to each other. 5-10km is optimal. Here's my docking craft in its 75km orbit catching up to my station:

Now is when that flag you planted comes in handy. Switch to it and speed up time until the two craft are almost on top of each other:

Switch back to your docking craft and set your target vehicle as target. Speed time up until the target craft is direcly above/below the docking craft.

Exit map view.

You should see the target craft roughly 5k away, and are now ready to commence rendezvous. Quick-save here!

Let's get terminology nailed down:

Your navball has three modes--Orbit, Surface, and Target. When you get close to a targeted vehicle, it will automatically switch to Target mode. If you click on the navball mode box (where your speed is), you will cycle between these three modes. Since you are now in Target mode, you will have two pink markers added to your navball. The pink circle is the Target Prograde Marker, and the pink Y is the Target Retrograde Marker. Your speed in target mode does not indicate if you are moving toward or away from your target. The relationship between your Prograde/Retrograde Markers and the Target Prograde/Retrograde Markers show you if you are moving toward or away!

Let's see how this works. We want to move toward our target craft. Find the Target Prograde Marker. Point your craft off to the side of the Target Prograde Marker opposite where your Prograde Marker currently is. Burn your engines and you will pull your Prograde Marker toward the Target Prograde Marker.

Keep burning and adjusting your course until you've pulled your Prograde Marker onto the Target Prograde Marker:

You are now heading directly toward your target! Look at your speed, and the distance to the target craft. You want your speed to be roughly 1/100th the distance to the target. If it's 5km (5,000m) away, you want your speed to be 50m/s. If it's 2,000m away, you want to be going 20m/s.

Once you're heading toward your target at your initial closing speed, flip your craft 180 so you are looking at the Target Retrograde Marker. As you close, your Retrograde Marker will drift off the Target Retrograde Marker. PUSH your Retrograde Marker back onto the Target Retrograde Marker by burning your engine. This will slow you down. You only need to correct course and speed every so often. If I start out at 50m/s closing speed at 5km, I'll burn at 2.5km, 1.2km, 700m, 300m, and 100m at which point I'm going 1m/s.

A big issue during this process is overburning. You end up going 1m/s while still 1km out. Worse, you burn so much you start moving away:

Don't freak! Simply flip 180 until you're looking at the Target Prograde Marker, and PULL your Prograde Marker back onto it and you get back to a good closing speed:

Remember, if you see your Prograde Marker around the Target Retrograde Marker (or your Retrograde Marker around the Target Prograde Marker) you are moving AWAY from your target!

OK, let's finish this rendezvous.

Here I am 160m out moving at 1.3m/s. This is a great place to quicksave!

Once you get this close, turn on your RCS and use it to finish the rendezvous. Quit watching your navball and just pay attention to how fast you are going and how close you are. Use RCS to apply the final brake.

Congrats! Your rendezvous is complete, and you're 90% docked!

Use your bracket keys [ or ] to switch over to your target vehicle. Take a look at where its docking port is. Does it look like this?

If so, you will drive yourself nuts trying to dock with it! Docking ports pointing east/west will move as the craft rotates around its orbit. Don't try to dock with a port that's facing east or west! Instead, slew your target craft around so your target docking port is pointed south. A docking port facing north/south will not move if it's fairly near the center of mass. To keep things as simple as possible, point your target port south!

Now switch back to your docking craft. Point its docking port north, and square off so you are looking at its back and facing forward. (Remember that light we put on it back in the VAB? This is why!) Click on the target port and set it as target.

You are now ready to commence docking procedures!

Press i to move toward the target port. You don't need more than .4m/s of speed.

Now, is your target port above or below you? Use the h or n key to raise or lower your docking port so that there's a bit of a gap between your docking port and the target docking port. Once you have that gap, brake using the opposite thrust. In this case I'm above it, so I used n to create the gap, and h to brake.

Now use the j and l keys to adjust left/right. Keep the target port centered as you approach.

USE GENTLE TAPS ON THE RCS KEYS! Mashing keys at this point will spell doom. Don't mash, tap! You should be closing in. Rotate your view around every so often to keep an eye on the separation. When you get to 10m, press k to lower your speed down to .1-.2m/s.

When the ports line up and are close enough to each other, the docking magnets kick in. Don't freak out if the ship suddenly surges on you. It's supposed to happen! Hey, look, you've docked!

To sum up:

--Good orbits lead to good rendezvous

--Good rendezvous leads to simpler docking

--Point the target docking port south, and the port on the docking craft north

--Work one axis (forward/back, up/down, left/right) when docking so you know what the ship is doing

OK, that's it for my rendezvous and docking tutorial. Let me know if it was useful or gibberish!

Edited March 5, 2014 by ArmchairGravy

[Dispatcher]

Nice work. Docking hasn't appealed much to me, but your tutorial has motivated me to make a serious try at some point. Previously, I'd simply ruled it out. Thanks!

[Javster]

I usually have an "abort key". Not the action group, just a key (usually k) which I press to get clear of the station if something goes wrong.

[Phylan]

I've read/watched a lot of these because I've been having a hell of a time trying to dock, and this is by far the most thorough and easiest to understand that I've read. That 1/100th tip for target velocity is clutch. Thank you!

[Jank]

Good tutorial. Makes the navball rendezvous method easy to understand. Wish I had seen this before I learned the hard way.

But then for docking you switch to eyeballing it... that's still doing it the hard way.

Might be beneficial to keep with the navball approach and illustrate docking with the navball and the docking port target/control method.

[ArmchairGravy]

Good tutorial. Makes the navball rendezvous method easy to understand. Wish I had seen this before I learned the hard way.

But then for docking you switch to eyeballing it... that's still doing it the hard way.

Might be beneficial to keep with the navball approach and illustrate docking with the navball and the docking port target/control method.

I have tried those approaches, but then I'm chasing around the target on the navball and getting frustrated with that. This way I know exactly the relationship between the two ports, what axis needs adjusting, and don't have to mess with docking mode or changing to chase camera. Even large ships are easy to dock precisely as long as I am squared off and pointing north.

[Jank]

Oh ok, I found the target-navball approach to be actually much less frustrating, which is why I suggested it. Never used docking mode, I just orient my craft the way I want it docked and then strafe around with RCS, very little chasing, although I do use chase cam. Back when I eyeballed it, I found myself constantly panning my camera around to see which axis was misaligned, and one always was, it seemed.

At any rate, it is good to have multiple methods on the forums. To each his own.