Precise docking

[justidutch]

I have a question about how to be absolutely precise when docking. I've been playing just over a year now, and I can dock ships no problem. I have just begun what is, for me, and extremely large venture though, and will require extremely precise docking manoeuvres. I am building a ring station (stock parts only), and it will take 8 launches to complete the ring. The ring is made up of the new MK-II crew cabin parts, stuck together with octagonal cubic struts set at 5 degree angles. So each of the 8 launches is a "ship" of 9 of the crew cabins. I have so far sent up and docked the first two segments, basically just eyeballing everything as best as I could

My question is, as I approach the station and have my new segment lined up to dock, how do I know that my orientation is exactly perfect? As in, how can I prevent my ring from becoming skewed? Is there some fancy docking view I don't know about that allows you to see you current ship's orientation compared to the station you are docking to? Perhaps a mod (although I sort of want to stay away from mods for now)?

Here are some pics. The engines will detach and crash back to Kerbin upon completion, leaving the ring by itself.

Edited December 12, 2014 by justidutch

[NASAHireMe]

Docking Port Alignment Indicator

[Alewx]

Join the group that is wishing for multiport docking.

BTW, what you are planning is pretty insane , but looking forward how it will look like after completion.

[Vector-5]

Or, slap a bicoupler onto the ends of the outermost cabins, and attach 2 docking ports to said bicoupler. If both ports are docked, then you know that the segments are aligned.

-Vec

[RainDreamer]

That mod that was given is the best thing you can ask for to align docking port perfectly for now. However, it is possible to ensure the ports only meet in a certain orientation by using keyed designs, like putting on certain obstructions at meeting points in a way so that there is only one orientation that will allow the ports to connect without the obstructions keep them away. It is harder to do, and will involve needless parts though. But it will be foolproof.

[secretformula]

That mod that was given is the best thing you can ask for to align docking port perfectly for now. However, it is possible to ensure the ports only meet in a certain orientation by using keyed designs, like putting on certain obstructions at meeting points in a way so that there is only one orientation that will allow the ports to connect without the obstructions keep them away. It is harder to do, and will involve needless parts though. But it will be foolproof.

Can you show an example of that? That sounds interesting

[Tex_NL]

My first thought when I read your other post was: 'Damn, that dude will have to do some extremely accurate docking.' (I know a thing or two about circular building. Check my sig for more details.)

Docking Port Alignment Indicator as suggested by NASAHireMe will help A LOT. It will tell you your rotation with 1/10th of a degree accuracy.

Another great option is to use MechJeb to help you. I am no fan of MJ's docking pilot but I do like Smart A.S.S. as it can hold your crafts rotation while you concentrate on the actual docking.

[phunk]

I tried something similar once. I was not precise enough. You can't see it from this angle, but the ends are offset and would not meet up when the last pieces were put in.

[RainDreamer]

Can you show an example of that? That sounds interesting

Serveral examples in this thread: http://forum.kerbalspaceprogram.com/threads/101418-Keyed-docking-ports?highlight=keyed+docking+port

[justidutch]

Thanks for the replies so far, everyone. Good ideas here, but keep them coming. Right now I'm thinking of keeping it stock. Don't really know why, something to do with not having come remotely close to exhausting all its possibilities yet. So, here's what I am thinking at the moment, though there are several hours in the work day left before I can actually try anything out, so more ideas are welcome. I will build some sort of key structure using girders, like a tongue-and-groove system. And I'll build it onto the boosters so that when they decouple and crash back to the ground I won't have the needless part count.

[Brainlord Mesomorph]

I will build some sort of key structure using girders, like a tongue-and-groove system. And I'll build it onto the boosters so that when they decouple and crash back to the ground I won't have the needless part count.

Wings have nice angles and can be used to guide things into slots.

HTH

[Claw]

I will build some sort of key structure using girders, like a tongue-and-groove system. And I'll build it onto the boosters so that when they decouple and crash back to the ground I won't have the needless part count.

I was going to suggest something like this, assuming you wanted to stay stock. I've done it before, but it can be really aggravating for large structures. Sometimes those lock & key setups need a lot of precision to get lined up which can be a pain when maneuvering large components. When I use the lock & key, I attach them with the structural pylons. When you detach the structural pylons, they don't leave anything behind.

Also, if you didn't know, you can get the components docked together and quicksave. Then undock them, keeping the docking ports very close together, and make fine tune adjustments. Then do another quicksave (probably with ALT+F5) and quickload. Doing that will reset the ports and they will snap back together without having to get too far apart. I've managed to get 0.0 rotation in the save files using this technique.

By the way, that looks like it will be awesome when complete. I don't think I've seen the MK2 parts used like that yet.

Good luck!

~Claw

[Jason Patterson]

You can allow part collisions and place two docking ports on the end if you don't want to use a bicoupler. It pretty much guarantees alignment. Alternatively, build a double wheel such that both segments must be docked at the same time - again, guaranteed alignment.

[Kryxal]

If you're going to alt-F5 one, I'd suggest doing it in the "initial docked" configuration, then a simple F5 once aligned as you want it.

[StormKat]

I can vouch for the bicoupler. It makes absolutely sure the alignment is precise.

[justidutch]

So last night I tried the lock+key, or tongue+groove system with girders. It helped with the visual lining up the orientation, but instead of gently nudging the ships into an exact position, they just clipped into each other. So, when I next have a block of time (probably not until the weekend) I will try the dual-docking port on a bicoupler. Or perhaps a tri- or quad-couple. Just cuz!

In the meantime, in the plane hangar I managed to create an entire ring as one structure. Now I must create some sort of crazy lifter to get it into orbit. Also, since my intention is to create about the largest ring possible, perhaps I continue researching precise docking techniques, then when the 0.90 update is out, proceed to create the ring station with the larger MK-3 crew cabins!

[Tex_NL]

Something like this?

IIRC it was close to 90m diameter.

[justidutch]

yup, something like that! Nicely done!

[justidutch]

I found myself with some time yesterday, and restarted the ring station project using a keyed pair of docking ports for connecting the segments together. I am exactly halfway through building the ring, and this docking technique is working beautifully. Thanks to all who responded to this post, I shall now dish out some rep for you. Below are a few relevant pics, and I reserve the right to necro this in a few days or a couple weeks when the station is complete, just in case any of you want to see the results of the precise docking technique being employed. Cheers!

[phunk]

Nice! Will you turn on all of those engines when it's done and see how fast it spins?

[Alewx]

I found myself with some time yesterday, and restarted the ring station project using a keyed pair of docking ports for connecting the segments together. I am exactly halfway through building the ring, and this docking technique is working beautifully. Thanks to all who responded to this post, I shall now dish out some rep for you. Below are a few relevant pics, and I reserve the right to necro this in a few days or a couple weeks when the station is complete, just in case any of you want to see the results of the precise docking technique being employed. Cheers!

http://jscript.ca/ksp-images/ring/Screen%20Shot%202014-12-11%20at%205.12.58%20PM.png

http://jscript.ca/ksp-images/ring/Screen%20Shot%202014-12-11%20at%205.57.44%20PM.png

http://jscript.ca/ksp-images/ring/Screen%20Shot%202014-12-11%20at%206.12.32%20PM.png

http://jscript.ca/ksp-images/ring/Screen%20Shot%202014-12-11%20at%206.12.53%20PM.png

http://jscript.ca/ksp-images/ring/Screen%20Shot%202014-12-12%20at%209.03.38%20AM.png

http://jscript.ca/ksp-images/ring/Screen%20Shot%202014-12-12%20at%209.28.59%20AM.png

Of course we want to see the final result of it, and the solution you came up with is pretty nice and easy.

Oh and how do you bend the parts? The attach nodes to not allow this normally.

[Claw]

This is looking fantastic! I really hope the final two ends connect for you (at least well enough).

Good luck!

Oh and how do you bend the parts? The attach nodes to not allow this normally.

I believe he said he used surface mounted cubic struts, then attached the Mk2 segments to those.

Cheers,

-Claw

[Tex_NL]

Sliding in the 8th piece will be difficult as there will be very little space to move. You might find it a lot easier to first build a big S. Then cut that in half and dock the two semi-circles.

...

I believe he said he used surface mounted cubic struts, then attached the Mk2 segments to those.

...

That technique definitely works. Check the tutorial link in my signature to see exactly how it is done.

[phunk]

Sliding in the 8th piece will be difficult as there will be very little space to move. You might find it a lot easier to first build a big S. Then cut that in half and dock the two semi-circles.

His docking ports are setup in a way that won't allow mounting them backwards.

[justidutch]

Nice! Will you turn on all of those engines when it's done and see how fast it spins?

Heck no! Well, upon further reflection, perhaps when 0.90 comes out…

No, I would love to impart a small amount of spin to the completed station, but since there are no axle-type rotating parts, it would make the thing a bear to dock to. I shall just have to imagine the ring spins, so it can be functional as a docking/refueling/snack+martini bar/etc...

...Oh and how do you bend the parts? The attach nodes to not allow this normally.

On each of the MK2 crew cabin parts I've attached a cubic octagonal strut. When in the VAB, if you zoom in to the closest degree, you can angle it and still attach it close enough to the node to not notice. One must take great care, however, to make sure it is centered properly.

Sliding in the 8th piece will be difficult as there will be very little space to move. You might find it a lot easier to first build a big S. Then cut that in half and dock the two semi-circles...

Yes, I am looking forward to this challenge. I have a few ideas in mind, it may take several attempts. But this will be built at any cost. The Kerpocalypse is coming, best be prepared.