Help with docking

[Oberon]

Hello all, I recently put a space station core into orbit, and now I'm looking to attach a science lab. I was able to get the science lab into a very similar orbit as the core, but not exactly. They're both travelling at around the same velocity, ~2,050m/s, but the science lab is in a 217k by 219k orbit while the SSC is in a 209k by 215k one... And I'm not too sure where to go from here, any hints would be appreciated

[TheDarkStar]

If you get them into two identical orbits at different places, they are stuck in different places. What you have to do it get close (closer than 1-5km or so) and then kill your relative velocity, followed by a careful approach (probably with RCS). First, set the docking target as a target. Next, mess with your orbit so that you get a close encounter with the target. When you get there, decelerate with your main engines. Next, burn at the target to get close and then slow down relative to it when you are extremely close (basically when you can actually see it). From this point, use RCS to guide the craft to the docking port.

[RSwordsman]

I've found that when trying for a rendezvous, radial burns help out much more than pro/retrograde if you're a certain distance away. You can use the maneuver planner and drag the blue circles while watching the approach arrows line up.

[Oberon]

cheers guys I'll give it a shot

[Claw]

I recommend installing these. They helped me tremendously.

http://kerbalspaceprogram.com/rendezvous-tutorial/

http://kerbalspaceprogram.com/docking-tutorial/

Both written by blizzy.

Good luck!

[AlamoVampire]

Oberon, I am going to fly in the faces of anti-mechjeb players and suggest trying mechjeb and use its auto-dock feature. now, i know, the moment a BUNCH of players read my suggestion they furiously started to type rebuttals against my suggestion, but if all of you fine kerbonauts as well as our dear friend Oberon will hear me out.

I could not dock efficiently to save my life, no matter how hard I tried, I just could not get it to go smoothly. I read all the step by steps, watched all the videos, then I read a single suggestion. Try MechJeb. I thought to myself: Self, I do not want to use mods, mods are cheating. Then I tried to dock again. That convinced me to give it a whirl. I also saw a video by Scott Manley that showed Romfarers Lazor Docking Camera mod, which gives a NASA style camera from a docking ports point of view with various docking information as well <which I have yet to understand, but the pictures on screen showing my target help. I use Mechjeb for a BUNCH of stuff, but, when I used it the first time to dock, it showed me how to dock. simply watching it dock MY ship to my other ship showed me under game conditions what it was I was doing right <launching at the right moment> and what I was doing wrong. THAT list is too long lol. Suffice it to say, it showed me how to dock, it taught me step by step simply by showing MY craft doing what it was able to do with how I built it. Ever since, it has been a vital part of my ships.

TL/DR Try mechjeb. it can teach you a BUNCH.

[thiosk]

First thing: Docking is something you have to be intuitively trained on. Astronauts train on this a long time. A mir cosmonaut complained that he wasn't prepared for docking, and borked it up, and seriously messed up mir by whacking into it. It takes a lot of experience that its hard to explain in forum posts.

So let me run through how I learned about docking.

First, I had randomly constructed ships and I tried to dock to one of those 6 way core connectors. For hours. Failure after failure. Thats when I realized, I had to put docking ports ON the docking connector part! Oh the humanity.

So, then I started slowly getting better at docking. I was able to at least link ships up, but it was a painful, awful process. But I got better at it. I tried putting together ships in orbit for interplanetary missions though, everything came out crooked. Lining up was horrible. Took forever every time, but at least I could do it such that it was no longer the critical step of a mission.

The key concept for me was learning about RCS balance. You see, those jets you're using to manipulate your ship, if one end of the ship pushes harder than the other, the ship twists all over the place in response to every kick you give it. WHAT A PAIN IN THE BUTT. So, find the center of mass of the ship (accounting for the fact that fuel drains..) and put space two sets of 4-symmetry thrusters equidistanct from it. The further the better.

So now your ship is level.

Time to learn the nav ball. Theres a lot of tutorials on this, and from your post it sounds like you can get near the ship, but you aren't really approaching it. See where it says "orbit" and velocity on the nav ball? Set your target to the ship you'd like to dock, and click "orbit" velocity screen. The nav ball changes to "target" mode and shows speed relative to the ship. This was an omg moment for me. It takes practice, but you learn to intuitively push the prograde and retrograde vectors around to optimize your approach. Usually I come in from behind the target, then I push the retrograde vector to line up with the ship. When I get within a click of the target, I fire and zero velocity. Then, I use my balanced RCS space craft to get lined up and docked. I make it sound easy here. It is easy, but its hard to "get it". As soon as you do, its like riding a bike.

Finally, theres a docking port camera. This takes practice to really intuitively understand, the tutorial makes it seem so easy. But at least you can figure out how to get pointed in the right directions. Now, I use that sucker and whip stuff together in orbit so fast it makes your head spin.

Heres what I'm working on this week:

It has a big booster on the bottom because I'm taking the whole thing to laythe-- but I have to add the rest of the parts I need. That thing with the solar panels coming off it-- thats a seperate space station core. I'm putting one in orbit around every moon of jool, and the whole thing is designed to be intercompatible. The reason this is relavent is because its really just a gigantic docking operation. I'd never bother unless docking was the easiest thing to do in the game.

Edited January 27, 2014 by thiosk