Docking

[Bidule]

Hi!

Is there a way to "auto-dock" with MechJeb? (or an other mod) I have two big ships that I'm unable to dock. I find it easy with small ones, but with those two I'm unable...

Thx!

Edited March 5, 2015 by Bidule

[RW-1]

What is it about these larger ships that is giving you trouble?

Larger ships - larger mass to work with, and affectionately you need "moar thrusters" and placement to make sure that when you are using the tug and that payload that it isn't offset from COM

(IOW RCS is evenly spaced from COM on the tug/payload, makes a huge difference in control), which I'm only assuming is the issue, if not let us know.

[Bidule]

Yes it's my problem. I don't have enough thrusters on my two big ships. But now it's too late to fix that. I spent so much time trying docking... I'm getting sick of it. So I tough I could "cheat" once and get it done automatically... And learn from my mistakes.

[Kelderek]

MechJeb does indeed have a docking autopilot mode, but it also requires that your ships are properly designed with balanced and sufficient RCS thruster placement. Make sure your RCS thrusters are symmetricly placed on opposite sides of your CoM. When docking two vessels, it's usually easiest to control it from the smaller of the two. Also, make sure you select "control from here" on your docking port before you start and select the docking port on the other vessel as your target.

EDIT: Also, there is a difference between not having enough thruster power and not having them in the right locations. In the former case movement will be balanced yet slow (usually happens on large ships), in the latter your movement will be unbalanced and harder to control (translation moves cause rotation, etc.).

Edited March 4, 2015 by Kelderek

[Mister Dilsby]

Don't panic! Before you give up entirely, have you done all the things to make docking as easy as possible?

--Orient ports N-S (one points heading 000, one points heading 180) Assuming you are on an equatiorial orbit, ports aligned in N-S direction will stay aimed in that direction. If you are not equatorial, point the ports orthagonal to prograde.

--Get as lined up as you can using main engines This doesn't work on all ship designs of course, but sometimes when RCS thrust is weak its the only way. Hopefully you have sufficient gyro torque to orient the ships' headings where you want them. If main engine thrust is too strong for effective control, you can tweak it lower by right-clicking.

--Pick Up Your Visual Scanning! Sometimes you cannot trust the navball to aim for the port, if the port is not on the ship's central axis. I like to put the camera directly under one of the ports and rotate views until I'm satisfied the other port is lined up in every direction

--Sort Out Directions In Advance You need to know as you're coming in which way the "IK" and "JL" key pairs are going to send your ship.

--Take It Slow! Invariably you are going to end up 5 meters from the target and be misaligned. If you're going slow enough toward target you should be able to make a lateral correction (see Sort Out Directions In Advance, above) and magnetics will pick it up from there.

Likely you are already doing many or all of these things, but often a small tweak to technique can be the difference. Good luck!

[Kryxal]

Also note that H/N are most likely to be well-aligned on your ship, and hitting caps lock can help compensate for poor CoM placement (but gives greatly reduced thrust). Just do your best to line it up and if you can ever get everything centered (direction AND velocity), no matter HOW slowly you're drifting together, you're practically done.

[eddiew]

This is probably easier than you think - It's quite possible to dock without thrusters, if you're careful

Get the ships close to each other (<100m) and kill relative velocity with the main engines. If you're struggling for fine control, right click and thrust limit the engines to 20% to give yourself more margin for error.

Control each ship from the docking port, target the other ship's docking port, and tell the pilot (or MechJeb's Smart A.S.S.) to point at the target. You now have a vector between the targets that is one of the IJKLHN translation keys. If either ship has a nosecone docking port, that's obviously the one to move since it'll be better balanced

*edit* As others have said however, MJ does have a docking autopilot - but I think some of the features are unlocked in the tech tree so it may not be available to you at this time. It usually does its job accurately, but it is woefully inefficient. Getting your ships into alignment first will massively reduce the amount of monoprop MJ burns on the final approach.

Edited March 5, 2015 by eddiew

[Bidule]

Thanks for you help! Will try as soon as I get home!

[Montag]

Forget the N/S stuff. Get Docking Port Alignment Indicator by Navy Fish.

[Kryxal]

The good thing about pointing radial/anti-radial is that your orbits will not cause you to drift off-axis once you're in place. Being 100m away prograde/retrograde means you'll effectively circle the other ship in the course of an orbit, 100m normal/anti-normal gives you a slightly different orbital period, radial/anti-radial causes an intercept about a quarter-orbit along.

[Bidule]

Did it! After many hours and many F9... I finally dock and landed on Eve! I sent a mini rocket with allot of RCS fuel. It was really easy to dock with this small rocket. Then, I had enough fuel to dock my to big ships together.

My mission was to land an 11 kerbals base on Eve. With docking port, ... , and an antenna. Guess what?!? I forgot to put an antenna!!!!!! Facepalm

Edited March 9, 2015 by Bidule

[eddiew]

With Kerbal Attachment System you could airdrop a small probe with an antenna, then have one of the kerbals attach it to their base.

Might as well, since it'll probably be decades before they come back from there

[Bidule]

Since I'm not good at landing twice on the same spot, I thought I could send a rover with a docking port and antenna. Now I need to figure out how to make my rover so both docking ports align together.

I love those "rescue missions"