Docking in space

[CuAnnan]

So I'm trying to build a segmented space station in the latest vanilla through steam.

The targetting reticules and distances all seem to only refer to the cupola module that sits atop my main station and I can't seem to change it.

I've set the target for the clamp-o-tron docking port and I'm controlling my second segment from its docking port.

Is there some other step I need to undertake to ensure that things are the way they should be?

And is there any way to have the navball's horizon be relative to the docking point as opposed to the body around which you are orbitting? which is about as useful as a baseball bat at a tennis match.

[cantab]

If you select "control from here" the navball orientation should match the docking port's orientation. Do check the port isn't backwards, a common problem with the Sr ports.

The target direction indicator can be a bit off and the distance tends to ignore that selection altogether, so you may have to use visuals as well as the instruments.

The horizon on the navball is always going to be that of the orbited body, that's kind of the point. V toggles between camera modes, "chase" makes the camera orientation match the controlling part, and can be useful for docking (and driving and atmospheric flying for that matter).

[SkyHook]

A couple of tips:

1. Set your different craft's orientation to the Normal + or Normal - orientation. This is at 180 (South) degrees or 0/360 degrees (North) if your orbit is a prograde orbit with 0 degrees of inclination. As you move around the planet, the craft will spin about its longitudinal axis, but the docking port will stay in the same orientation. This allows you to take much longer to dock than normal.

2. Watch Scott Manley. Seriously he is the best of us.

To answer your questions, everything sounds good. The distance on the navball is the linear distance from your point of control to the docking port. As far as the horizon is concerned, I'm not sure that I know what you are referring to. Placing your navball in target mode (by clicking on the box where your speed is) may help.

[G'th]

Once you have a target vector and pro/retrograde marker, you're all set to dock, at literally any possible distance where a target vector will appear.

At that point, the first step is to slow down to a speed manageable by RCS. 0-50m/s is ideal if you have at least 4 RCS pods. After that, the key is to just use your RCS controls to move your grade marker onto the target, and then use the RCS to move towards the target while keeping those two markers lined up.

As you approach your target, you'll likely have to maneuver around to orient the two craft properly. Be sure when you make these alignment adjustments to turn off RCS, as otherwise that will throw off your velocity and you'll have to expend more fuel to correct it. If you take a slower approach, however, it is possible to keep RCS on and use it to align the two crafts.

Once you can verify that your two ports are aligned properly, all it is is a matter of matching the grade and target vectors again and moving towards the target.

That is the best and most efficient method for docking, short of literally timing your burns and craft orientation in such a way that you dock automatically at your closest approach. (IE, hitting a 1cm target on a moving train while riding a horse that's trying to buck you off. OH and your blind folded and have no arms)

[Pecan]

Go mods:

NavyFish's docking alignment window is probably best known.

The NavNallDockingAlignmentIndicator is a more minimalist tool derived from it.

RMP's docking mode will give you a TV view from your ship's controlling docking port.

MJ's custom window editor will let you display all the docking figures you can dream of, if you can cope with raw numbers.

These four, I know, correct for the target port, not just the target ship's Centre of Mass. There are several other mods which also give improved docking information/views.

[Wanderfound]

All the above is good advice, but also: practice, practice, practice. Once you get the hang of it you can do it purely by eyeball.

[zarakon]

Once you get the hang of it you can do it purely by eyeball.

Or purely by navball!

[Laie]

Or purely by navball!

Depending on where you have the docking port, the navball may lead you astray. We've been through that not too long ago:

http://forum.kerbalspaceprogram.com/threads/86086-docking-woes-navball-parallax-error

Second page details why the navball can be wrong. The only solution is visual control or some of the docking indicator mods. Some of them are linked on the first page of that thread.

[Mesons]

As you approach your target' date=' you'll likely have to maneuver around to orient the two craft properly. [b']Be sure when you make these alignment adjustments to turn off RCS, as otherwise that will throw off your velocity and you'll have to expend more fuel to correct it. If you take a slower approach, however, it is possible to keep RCS on and use it to align the two crafts.

Try placing your RCS ports symmetrically about your CoM (where it will be when docking), with each one in a pair the same distance away from the CoM and opposite each other. This should eliminate any unwanted rotations and any change in speed from using RCS for rotation only, and it should make translation not cause any rotation.

Edited August 11, 2014 by Mesons
Clarification

[G'th]

Try placing your RCS ports symmetrically about your CoM (where it will be when docking), with each one in a pair the same distance away from the CoM and opposite each other. This should eliminate any unwanted rotations and any change in speed from using RCS for rotation only, and it should make translation not cause any rotation.

That wasn't what I was talking about. I was talking about using torque to move your craft around so that it's aligned with the target. If you keep RCS on while doing this at relatively higher speeds, it'll throw you off into a direction you didn't want, regardless of whether your RCS are placed perfectly or not.

[Mesons]

That wasn't what I was talking about. I was talking about using torque to move your craft around so that it's aligned with the target. If you keep RCS on while doing this at relatively higher speeds' date=' it'll throw you off into a direction you didn't want, regardless of whether your RCS are placed perfectly or not.[/quote']

This shouldn't happen unless you are translating. If you have an equal number of RCS ports firing in opposite directions, you won't have a net force, so your velocity will not change. If your velocity does in fact change, there is a bug and you should report it.

[qazsedcft]

That wasn't what I was talking about. I was talking about using torque to move your craft around so that it's aligned with the target. If you keep RCS on while doing this at relatively higher speeds' date=' it'll throw you off into a direction you didn't want, regardless of whether your RCS are placed perfectly or not.[/quote']

That can also be corrected with RCS. Hit CAPS lock as you get closer (<20m) and fine tune your approach.