Docking Tips

[X9Squared]

Hi all,

I'm quite a newbie to KSP, only been playing for a few months, so I'm deciding to do my first-ever docking between a fuel-tank thingy and a command module. Anybody have some tips that I should heed? I read the wiki article on orbital rendezvous, but it would be nice to have a few more opinions on what I should prioritize and what might go wrong.

Thanks everyone in advance,

X9

Edited August 11, 2015 by X9Squared

[Alshain]

You mentioned two different things docking and rendezvous though related are not the same task. (For example, NASA's first rendezvous was with Gemini 6 and 7, while it's first docking wasn't until Gemini 8). Rendezvous comes first, but have you tried yet? Is there anything specific you need help with?

One problem I see frequently with rendezvous is if you want to go toward the target, burn toward the target prograde (pink circle), if you want to halt relative motion burn to your retrograde in navball target mode (yellow X). Do not burn to the target retrograde (pink X).

Edited August 11, 2015 by Alshain

[X9Squared]

Thanks, I haven't tried either yet, looking for some tips for both.

[Geschosskopf]

Rendezvous depends on knowing how to do certain maneuvers, and it's really no different from going to Mun.

Actually docking is a LOT easier if you made sure to design the ship with balanced RCS thrusters so you get no unwanted rotations when translating laterally. I recommend the =http://forum.kerbalspaceprogram.com/threads/35996-1-0-2-RCS-Build-Aid-v0-7-2]RCS Build Aid mod for that. I also recommend Navy Fish's Docking Alignment Indicator, which REALLY helps getting everything lined up correctly.

[Alshain]

While I use DPAI, I don't recommend it for the first time, or even the second. You should try to learn the skill with stock first (though RCS Build aid is fine) and then use DPAI to take away the tedium of it. If you are using RCS Build Aid, remember to factor in what stage you will be on when docking, aligning RCS with your entire rocket won't work. Also remember to estimate how much fuel will be in your tanks when you go to dock. It's doubtful they will be full.

[X9Squared]

Thanks everyone! I'll check out those mods, though I'll try a docking manuever once without them, then try it with the mods. Wish me luck!

[Geschosskopf]

While I use DPAI, I don't recommend it for the first time, or even the second. You should try to learn the skill with stock first.

Disagree. It's way better to see what's going on, so you can really understand the process. Once you grok it, then you can do it blindfolded, but learning is best with illustrations

[Fearless Son]

You know that little velocity indicator above your navball? You can click that to cycle through what your velocity is relative toward. In the case of rendezvous and docking, once you have navigated a good intercept point (less than two kilometers is best) you can click that velocity indicator until it says "Target", which is your velocity relative to the target you are trying to rendezvous with. This also changes your prograde and retrograde vectors to be relative to the target as well. Once you are at or near the point of closest approach, you can burn toward your retrograde vector until the relative velocity is nearly zero. Then you should be drifting fairly close to your target, without need of major adjustments. Point your nose directly at the target, give it a little acceleration, and watch it approach. Take it slow here, there is no incentive to rush and every incentive not to; overshooting is bad, collision is worse. Point retrograde and kill the velocity when you feel you are close enough, usually about fifty meters.

Once floating next to your rendezvous target, right-click the docking port on your ship, select "Control from Here". That will make the the navball consider that the "front" of your ship. Right-click on the docking port you wish to connect with on the other object, and select "Set as Target". That will set that specific object on the other ship as your rendezvous target. Now your navball should be ready for an accurate docking. Activate your RCS, and use the translation keys while in normal staging mode to line yourself up (I prefer to avoid docking mode entirely but your experience may vary.) The translation keys are I, K, J, L for up, down, left, and right respectively, and H and N for forward and backward respectively. You want to get it so the target vector is right in the center of your navball, and your prograde vector is right in the center of the target vector. If the other ship supports this, switch to it instead, and have it rotate to face its docking port toward your ship, that will make this simpler. If not, you will have to translate your ship around the other to line your ports up. In either case, once the ports are pointing at one another and the velocity is zero, use the forward translation on your RCS to nudge yourself toward the target, then use the lateral translation keys to trim the prograde vector until it lines up with the target vector.

After that, the ships should coast together. You will know you did it right when the docking ports start pulling the ships together with magnetic forces. At the moment this starts, disable your SAS. The SAS will want to "correct" for the unexpected force, and that might overpower the magnets. You need to disable it to let them do their job. Once the ships "combine" and get treated as one ship instead of two, docking is complete. Congratulations.

Edited August 15, 2015 by Fearless Son

[Sharpy]

One more tip. When close to target ship and moving slowly, watch how pressing IJKL and H and N move the prograde vector around the navball. It's much easier to dock using primarily the navball and only supporting yourself with the main screen than trying to aim the actual port while ignoring or barely glancing at the navball.

[jarmund]

Short and simple:

1. Try to time your launch to an orbit slightly higher and in front of the target

2. If you're lucky, you can do your final approach from here

3. If you're not (most likely), your first priority should be to match planes with target: Burn normal (north, most likely) on the descending node, and antinormal (south, most likely) on the ascending node until your relative inclination is 0 or NaN.

4. Make sure you know how the navball works, when it comes to orbit mode vs target mode. When in target mode, try to keep your prograde and target vectors as close as you can, without too much relative velocity.

5. When close, in target mode, burn retrograde until your relative velocity is 0

6a: Eyeball it to dock

6b: Install docking port alignment indicator and dock like a pro

[Wemb]

... NASA's first rendezvous was with Gemini 6 and 7, while it's first docking wasn't until Gemini 8). Rendezvous comes first, but have you tried yet?

And their first attempt was with Gemini 4 - which they hopelessly balls up in exactly the same way most people do playing KSP. Orbital Rendevous is non-trivial - and until you've masteed it, don't even worry about docking.

But, as for docking? Obvious things are - ensure your craft have the same size docking ports, and they're both attached the right way around on the ships so they'll actually mate (it's easy to put them on back-to-front, and we've probably all at some point sent a ship up with the wrong sized port on).

Don't forget to put RCS thrusters on one of the vessels, and ensure that the other vessel isn't spinning when you're trying to dock.

Make sure everyone has sufficient power - but fold up any vulnerable solar arrays before you try.

Use a mod to give you a docking port alignment indicator - doing it with the Mk 1 eyeball is fairly insane,

And, most of, be gentle. Real gentle.

Good luck and godspeed!

Wemb

- - - Updated - - -

One more tip. When close to target ship and moving slowly, watch how pressing IJKL and H and N move the prograde vector around the navball. It's much easier to dock using primarily the navball and only supporting yourself with the main screen than trying to aim the actual port while ignoring or barely glancing at the navball.

Yup - what Sharpy says. Indeed - now when I dock, I'm mostly doing it from inide the cockpit using the prop MFD displays from RasterProp Monitor - this isn't to make it more difficult, but because a) there's a very useful docking camera in it, and it's a -lot- less distracting not being able to see what's going on.

When you're docking, what you -really- need to know is a) are you pointing in the right direction how fast are you going compared to the target c) what's changing and how fast is it changing.

If your instruments can answer these questions, then you're better off watcing them than looking out of the window.

Wemb

[Auriga_Nexus]

Couple of things I've done to help with docking. Firstly, if you have a control stick/joystick, you can set it up to be able to rotate and translate simultaneously without switching modes or using the IJKL keys. I have my Logitech 3D Pro set up so that stick movement controls my rotation axis and moving the hat switch controls my X (L/R) and Y (U/D) translation thrust. For forward/backward RCS thrust I have two buttons on either side of the hat switch that handle that.

Secondly, you can dock even without looking at the outside of your ship, if you know how to use the MFD's in the cockpit. Basically if you click on the buttons above and below the MFD screens in IVA view you can get different displays that will tell you about your ship, orbit, etc. First you want to be on the target select screen which is top row third from the left. You can use this to select your target docking port as well as your reference port. Then you click the button on the far right of the top row to pull up the docking indicator. There's an orange circle that indicates your rotational alignment, put that dead center and you should be facing the direction of the docking port. (If you see an orange arrow rotate in the arrow's direction until you see the circle). Once you've done that, use your X and Y translation to line yourself up. There are two green lines, a crosshair, and a prograde/retrograde indicator. The P/R indicator shows your translative velocity, the crosshair is your docking port, and the green lines are the target docking port. You want to move up/down and left/right until both the green lines and the P/R indicator are dead center. (If your P/R indicator is off center the lines will move in the opposite direction. The further your indicator is from center, the faster the lines will move. Use this to help guide your movements.)

Once you have the orange circle, the prograde/retrograde indicator, and the green lines all centered on the crosshair, you are lined up and ready to dock. At this point just move forward or back until you touch. The crosshair display also shows the distance and relative velocity between the two docking ports. Just before you make contact you want your relative velocity to be 0.1 or less, this will ensure you dock properly and you don't bounce off the other port.

If you learn how to use the cockpit MFD's you can line up and dock without even seeing what you are docking to. Whenever I add modules to the KISS (Kerbin International Space Station), I typically use a 2.5 m docking port on the back of my vehicle, and a command pod with ILX thrusters on the other side of the module to be added. Once I dock the module I use a stack separator to disconnect the command module (which leaves a second docking port open for the next module) and head back planetside. Thus, when I am docking I am typically facing away from my target and backing in, which makes the MFD's in the cockpit very useful.

[Wemb]

Secondly, you can dock even without looking at the outside of your ship, if you know how to use the MFD's in the cockpit. Basically if you click on the buttons above and below the MFD screens in IVA view you can get different displays that will tell you about your ship

Just a note - you need to have the RasterPropMonitor mod installed to get the working MFDs in IVA view. It also integrates with Docking Port Alignment Indiciator - though DPAI isn't really needed thanks to the tools that A_N above comprehensively described.

Wemb

[X9Squared]

Wow. Thanks everyone, I didn't expect to get so much outpouring. I tried to dock, but missed my orbital plane and ended up putting another satellite into orbit. Oh well, I'll try again tomorrow.

[match]

Nav Ball has big mojo. Listen to Nav Ball.

Windows lie!!

You go dock now!

Brought to you by Dockers without Borders

I really have nothing further to add except hoping you persist until successful. Is a good feeling once you get it.

[legoclone09]

What I do is make SMART A.S.S point both towards target and then press H and timewarp. I'm so lazy

[Ripper2900]

Another tip I found useful the first times I was docking (before I knew about the Docking Port Alignment Indicator) is to use the locked view mode. Press "'v" repeatedly untill it says "locked". This will change the view to be relative to your own craft. It will make it much easier to do translations and rotations. It can get pretty confusing to keep track of what is up and down while you maneuver around your target. With locked view, it's a breeze.

[lugge]

Wow. Thanks everyone, I didn't expect to get so much outpouring. I tried to dock, but missed my orbital plane and ended up putting another satellite into orbit. Oh well, I'll try again tomorrow.

And if it doesn't work on the first try (it probably won't), try again and again and again...

For me, rendezvous and docking were MUCH harder than my first Mun and Minmus landings.

What I did:

I acceptet 4 contracts for rescuing Kerbals from LKO.

I built a ship with an empty hitchiker and a command pot, and let Jeb start the mission.

Rescuing Kerbals is like rendezvous: you have to get to a short distance to them (50m - 2km) and have a low relative velocity (0m/s - 1m/s).

Rescuing the first Kerbal was a pain in the ass and took hours (yeah, hours).

The second one was easier. Number 3 and 4 were no problem :-)

After that, I accepted 4 more rescue contracts and did it all again.

I ended up with lots of funds (8 rescue contracts? Must have been some 800.000), lots of new Kerbonauts for free, and a lots of rendezvous experience.

After that, I started my first docking attempt.

As the others said before: rendezvous is a prerequisite for docking.

[Wemb]

Again, once you get used to not being able to -see- anything the MFD's in IVA mode are brilliant. They not only tell you your position/lack of position in rotational space (i.e if you're 180 deg out in some direction, which is more useful than an x,y,z locaton), they also tell your distance and approach velocity to the target and your x, y and z velocity at the same time on the same window. This really makes it a lot more easier than it can be otherwise.

Here's a good picture from the RPM thread:

Wemb

-

[Sirine]

Pro player usually dock with nav ball indicator and know what they are doing, and doing it really fast and confidence.

Beginner usually dock with visual aid mod. Auto docking mod etc. And view and feel and hope for the best.

What I said. Nav ball tells you everything you need to know for docking. Pay very close attention to it.

[cephalo]

Make sure to know that you can drag maneuver nodes along their path. That makes rendezvous a lot easier than making new nodes all over the place.

[KandoKris]

I F2 then eyeball once within 10 meters as some of my craft require an odd docking angle to "fit" but for the most part the nav ball and pink circle are all thats needed

[Korbit]

Welcome X9Squared! I am also a newbie and just successfully completed my first docking mission. So I gotta show and tell:

Preparing to Dock: http://www.screencast.com/t/veoxgPKiIWb

First Successful Dock: http://www.screencast.com/t/av2YyQcWcIj

Everything I read here is good information, but one thing I didn't see here or in all my other preparation for the first docking mission is to disengage your SAS just before you dock with the other ship. I didn't know that and I tried repeatedly backing out and slowly reengaging the other docking port. I was about to give up when I noticed my ship was slightly askew while resting against the other docking port, sort of like when your capsule is hanging from the 'chute with the SAS on. As soon as you turn it off the ship hangs freely, and the same is true for docking. As soon as I turned off the SAS I got that satisfying Ker-Chunk of a successful dock!

[Wemb]

... disengage your SAS just before you dock with the other ship.

Oh, yes, good one - let the magnets do the work.

Also - something else which can really make your life difficult if you forget - ensure your RCS thrusters are in line with the center of mass of whatever you're trying to dock - and check it still looks good when your vessel has fuel or not.

If you don't do this, and your thrusters do not coincide with your CoM when you try and translate you'll instead create a torque and your ship will, to some extend, try and rotate also. Your reaction wheel smay or may not be able to cope.

And, if like me, you're over-cautious and end up with an a stage left on your vessel which you weren't expecting - don't try and dock with it still attached - you'll probably go all over then place 'cause of the different CoM.

Wemb