Docking

[GPERKINS]

Hi,

Have been playing for a few weeks. I have a few Munar and Minmian landings.

However, i can't for the life of me dock. I have managed it once out of twenty attempts and i'm sure it was a fluke. I can get within 20m but cannot close the deal.

I dont use mechjeb. Any tips or even a mod to just make docking go easier (i want proper space stations dammit).

[Carsogen]

Hi there, welcome to the community!

The best thing I do is orient the ships so one is facing North, one South (North is zero degrees red line on navball, South is opposite). In an equatorial orbit these directions won't rotate with your orbit, so you don't have to worry about alignment as well as translation! Is there anything in particular you're having trouble with? ie. Unbalanced RCS, colliding etc?

Edit: Not that colliding isn't fun! Also docking takes some getting used to, I remember the first time I managed it was my greatest moment, just keep at it and I'm sure you'll have a space station before you know it!

Edited September 19, 2014 by Carsogen

[Starwhip]

Tutorial in signature should answer all of your questions. Just let me know if anything doesn't work, because I haven't updated the link lately.

[Moonfrog]

when you say 20 metres? do u mean 20 metres or 20 kilometres? Because 20m is pretty good, its literally next to the other object. If your that close, u just need to thrust slowly towards it and line up your docking ports.

If lining up is a problem, I can suggest using RCS, and design it so it moves you up,down,left and right relative to the direction your traveling in. Selecting the second movement mode, the one underneath stage mode, this will make your rcs move along vertical and horizontal axis.

2nd suggestion. When u select a target you can face the other object with the pinkish icon on the navball. If u do this with both craft, u can have them pretty much lined up exactly. Do it with each craft using the target option and then facing thee pink icon on the navball.

3rd suggestion find a camera view you are comfortable with. Some like freeview, others use chaseview, I suggest trying each and finding which one works for u.

5th when connecting, usually 2m/s is fast enough, I usually dock at 1m/s cos I'm a nervous wreck. I have seen others go up to 5m/s, unless your really good at it I recommend slowing to 1 or 2 m/s when joining up.

6th suggestion u can right click on your docking port and select control from here, this is useful if your docking port is somewhere else on the ship like sideways and not in the same direction as your main thrust.

7th suggestion. The RCS thrusters that look like 4 engines like a flower are good for docking, because u can also thrust forwards or backwards increasing and decreasing speed towards target.

8th suggestion, the pink icon on the navball indicates the direction of the target. The yellow one indicates your travel direction. If both are aligned on top of one another you are moving towards the target, RCS thrusters can be used to move the yellow on top of the target, up/ down, left right etc.

9th suggestion. Keys for RCS thruster control are H and N. Forwards and backwards. J,L left and right. I, K , Up and down. If u don't want to use the 2nd movement mode option.

10th. Turn of rcs when you want to turn your craft while docking for alighment, or it might push u in a direction u don't want to go. Put it back on when u want to move along axis in relation to your target again.

All I can think of for docking when your 20 metres close. If your at 20 km I do have different suggestions for that.

[Red Iron Crown]

Two mods that make it much easier to dock:

RCS Build Aid: Helps you build ships where the RCS system is balanced so that translating doesn't change attitude.

Docking Port Alignment Indicator: A display that show orientation and relative position between docking ports on two craft.

Aside from that, press CapsLock when docking to make your controls more precise, use the "Chase" camera mode, and most importantly be patient. It's not a race, take your time and use small inputs. It's harder to mess up when it's happening slowly, and recovering from errors is easier, too.

Edit: Multiple long winded ninjas.

[Godot]

I agree with the tips Monfrog gave.

As for useful mods ... I for my pat love raster Prop Monitor.

One of the screens in the supplied MFDs is for docking, allowing you to do a lot of your docking procedures from IVA.

Here is a short sequence of my lander docking with the mothership with the help of RPM:

http://imgur.com/a/diFKD#0

(all maneuvers during the final stages of docking were purely made with RCS thrusters ... the main engine of the lander didn´t get used at this stage anymore)

Edited September 19, 2014 by Godot

[RW-1]

I also think you can practice using the mun landing scenario, undock and move about to get used to it, then redock.

Get in docking mode, spacebar to flip between translation and rotation, and make sure you have selected the other PORT as the target, not just the ship itself.

(if near enough to ship you are going to dock to, right click the docking port and select as target.)

Although you said you did it once, I'll say this anyways; ensure both docking ports are facing the correct way, it's happened to more than one person.

Alignment is fairly important, but once close enough, the docking ports should attract and engage, I recommend turning off SAS just before or when you see that occurring.

I learned docking on orbiter, but once you have the concepts of translation/rotation down and the mechanics involved, you'll get it, for KSP I only had to learn the instrument representations.

[capi3101]

What Red Iron Crown said. I also highly recommend Docking Port Alignment Indicator.

In case you are having problems with the rendezvous, try this:

1) Target your target. In map mode, find the little chevron marked AN (or DN). Put a maneuver node on it, and then note the number it gives you; this is how far off the plane of the target you are. Pull on one of the little purple triangles - if the number goes up, you're pulling on the wrong one. Get that number down as close to zero as you can manage. Make the burn when it comes up. Rinse and repeat until you've got it at 0.0 or NaN (NaN means "not a number", which means you're so close to the plane that the programming language is barfing - it's "better than zero" in this case, though zero is quite enough).

2) Look for the little intercept chevrons. These will tell you where exactly you and the target will be when you come closest to one another. Look at the distance it's telling you. At your next apsis, put up a maneuver node and pull either prograde or retrograde. If the number goes up, start pulling on the other -grade. Do this slowly - you will reach a point where the number will start going back up; that's fine. Make the burn. Rinse and repeat at the next apsis.

CAVEAT: Don't let you periapsis go below 69,000 while you're doing this; if you de-orbit, docking will be a tad difficult. You also don't want to start trying to close the gap until the target is within a hundred kilometers or so; if it's more than that but the distance is still closing, wait a few orbits until the distance becomes a little more managable. You'll save fuel in the long run.

3) There will come a point when you won't be able to do anything more useful by going prograde and retrograde at the apses. You have two choices then - either do a radial burn at an apsis, or go prograde/retrograde at a midpoint between the apses. Pretty much the same as step number 2.

Ultimately if you keep this up, you'll get an intercept less than 2.2 kilometers. That's all the closer you need to get for a rendezvous.

Then comes the actual docking process. Your speedometer should switch over automatically to target mode as you approach - if it doesn't, click on it until it's up. This shows the relative velocity to the target. You want this number low (you're still travelling hundreds of meters per second, but you want to be travelling at roughly the same speed as the target and this tells you how far off you are). Mind your distance to the target. If your distance starts increasing, zero out the relative velocity (burn retrograde in target mode until it says zero), aim at the pink meatball on the nav ball (this is the direction of the target - make sure you're aimed at the meatball and not the little trifoil icon, which is the direction away from the target), and thrust forward. You want to be using RCS thrusters while docking unless you're still a good ways off - though when it comes to re-aiming at the target, you want RCS thrusters off (so it doesn't give you little annoying sideways motions). Zero out your velocity at 100 meters. At 50 meters, you want to have your target's docking port selected, and preferably you want it aimed at your craft. Easiest way to do that is to switch to the targer craft, target your ship, turn in the direction of the pink meatball, set SAS, and then go back to your ship. You'll probably need to re-target your target at that point but it should be pretty close to directly in front of you anyway. Keep up the pattern of aim-thrust-zero at regular intervals and you should make a successful docking operation.

Best of luck.

[lincourtl]

Blizzy has a great in-game docking tutorial mod.

[Scarecrow88]

If you just want to practise docking without having to go through the process of launching something in to orbit first, I created a set of scenarios that you can reset as often as you like until you are happy you can do it successfully. There are 4 scenarios you can download, which progress in difficulty, from 2 craft right next to each other to having to create your own intercept, to a ship built for a Mun mission which requires you to perform all the stages of a rendezvous and docking.

More explicit details of the scenarios and download links can be found in this thread :-

http://forum.kerbalspaceprogram.com/threads/86616-Beginner-to-Expert-Flight-Practise-Scenarios?p=1279271#post1279271

[LordFerret]

Getting there is one thing, getting lined-up and into place is another. There are plenty of tutorials out there to show you how to get there (and dock), watch a few different ones and see if one registers (makes sense) with you ... not everyone teaches the same lesson in the same manner/clarity.

Once you get there, cancel out any motion relative to the 'target'... trying to steer and control three axis with additional drift can be very frustrating (for me anyway lol).

Like a knife balanced for throwing, your ship should also maneuver via RCS thrusters smoothly - balanced. Nothing worse than ending up with a ship that 'steers' like a bus... if you know what I mean. Review the thruster placement on your ship, the ability to pivot about/around the center of mass is the answer (IMO)... and keep in mind that center of mass changes with each staging. Also, before sending your ship out to Mun or Minmus, launch a test flight and dock with your space station and see how it performs.

[tsotha]

I had the same problem in the beginning. The key for me was proper ship design - make your ship so the RCS thrusters are exactly at the ship's center of mass, and make it tight with plenty of struts. When you do translation (with I, J, K, and L), your ship shouldn't change heading at all, nor should the nav ball sway back and forth (indicating wobbling).

If you don't know how much fuel you're going to have when you dock, make sure you design your ship such that the center of mass doesn't move as your fuel depletes.

If you control both ships get the docker within about 20 meters of the dockee, zero out your closing velocity, and then rotate each ship's docking port so that it faces the other exactly: Set the other ship's docking port as the target, click "control from here" on your port, then line up your reticle with the pink tennis ball. Switch to the other ship and do the same thing. Then just give a little puff forward on the docker and you're in like Flynn.

Edited September 20, 2014 by tsotha

[Redshift OTF]

Here's how I do it:

1) Make sure you are parallel with the target port. Lined up so you know you can dock use the left, right, up, down, forward & backwards RCS buttons, (translation controls).

2) Use translation controls to get the pink target marker in the centre of your nav ball.

3) Make sure you are moving slowly towards the target.

4) Here's the real trick. Tap your translation controls so the yellow prograde marker is always over the pink target marker. As you get closer correct as needed.

As long as you have SAS enabled to keep yourself parallel with the target you cannot fail to dock with this method.

[Wanderfound]

As everyone else said.

The thing I found helpful was not to start by trying to dock big ships and stations together. Instead, build a pair of small, highly manoeuvrable ships that each have a docking port and well-balanced RCS. Launch the pair of them and practice rendezvous and docking with those until you get the hang of it before moving on to big stuff.

And go slow. At the point of contact, you want your relative velocities to be below 0.3m/s. Get lined up, close and stationary, then use the RCS to slowly approach. Hold the nose on target while you use the RCS translation controls to keep the target and prograde markers aligned. If translation makes your nose swing around, your RCS isn't balanced well enough. Place the thrusters evenly around CoM.

[pincushionman]

I made a couple of craft that sent both my craft up at once (like the Apollo CM-LEM) to train so I didn't have to worry about the rendezvous portion of the problem. That helped a lot to get the basics. Align your target port pointing normal to your orbit, that way you have to worry less about your (slightly different) orbits drifting apart as you work, or line up along your velocity vector when you're in a long, straight portion of your orbit. Get Docking Port Alignment Indicator. Make sure both of your craft have SAS engaged. Find a camera mode that allows you to freely move the camera to where the up-down, left-right controls match what you expect from what you're seeing.

The last one I haven't figured out yet. Every time I try to dock after a rendezvous, with the default camera mode I tend to approach gimbal lock at the most important camera position, which really ticks me off.

[Kryxal]

The funny thing is, for me, camera is optional on the final approach (except for rangefinding). Once things are aligned, which is often a case of point target vessel at docking vessel, note heading, put docking vessel on a reciprocal, I just go with navball, delta-v, distance, and it works fine.