Multi-Point Simultaneous Docking

[Mister Dilsby]

"Asking for a friend"...  no, seriously, I am about to start testing a large space carrier filled with various landing craft in cargo bays and other contrivances. Before I get going I thought I'd ask the community about their experiences.

The landers are going to be relatively large (biggest is over 40 tons) and I know they are going to wobble like crazy during carrier maneuvers if they are only docked at one point-- too many degrees of freedom.

The question: since 1.0.5, what have been peoples' experience with any or all of the following:

-- simultaneous docking to more than one port, same surface

-- simultaneous docking to more than one point, different surfaces (e.g. one on the ship's belly, one axial)

-- docking to a port followed by capture at a different point with the docking klaw

-- capture at multiple points with two or more docking klaws

Am really curious about the klaw solutions: in prior versions klawing was a really great way to get krakkened, and if we're talking about multiple docks involving a klaw, then at some point wouldn't the ship be klawing to itself? Weird. 

Hope this will be as helpful for others as it will for me. Please help and encourage others by 'upvoting' responses you think are good, on this thread and on others in the Gameplay Questions section. Top responder here may get a comics mention

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Because of the way things get threaded (or not) in this Forum section, I'm going to add to the OP rather than reply to answers:

ETA #1  -- I should have mentioned before -- stock solutions please. KAS, KJR, etc are great mods but I prefer not to use them.  

QUESTION to @Rocket In My Pocket -- to which orange tank surface was your "rock solid" three-port solution attached? End or side?

Edited December 16, 2015 by Kuzzter

[Rocket In My Pocket]

Great question, looking forward to seeing some responses.

As far as personal experience I had a ship that would dock to a large orange fuel tank and then trade out at the space station for a full one when empty, my first design only used one port to connect the ship to the large orange fuel tank and was a complete failure due to extreme wobble. The improved version uses 3 docking ports in a triangular pattern and is rock solid. Docking multiple ports on the same surface can be tricky and often requires multiple attempts, so it is a work intensive solution but it does work.

Can't help you with the rest, except to say that klaws would certainly be a disaster waiting to happen! Lol, best of luck!

 

[Snark]

Another option, if you're so inclined, is Kerbal Attachment System. One of the things it includes: deployable struts. There's a part that you can put on your ships which is basically a "strut socket". Send out a kerbal on EVA, right click on a couple of sockets, and they get linked by a strut. Unlink them the same way.

I like this solution because not only does it give my kerbals something interesting to do on EVA, but also because the radially attached strut sockets are small and unobtrusive; they fit onto pretty much any ship design.

 

 

Edited December 16, 2015 by Snark

[Tex_NL]

9 minutes ago, Snark said:

Another option, if you're so inclined, is Kerbal Attachment System. One of the things it includes: deployable struts. There's a part that you can put on your ships which is basically a "strut socket". Send out a kerbal on EVA, right click on a couple of sockets, and they get linked by a strut. Unlink them the same way.

...

Use KAS to augment Kerbal Joint Reinforcement and anything docked becomes virtually unmovable.

Use bigger docking ports. The big 2.5m clamp-o-tron is a lot stronger than the regular 1.25m. KW Rocketry contains an even stronger 3.75m docking port.

Edited December 16, 2015 by Tex_NL

[Kerbart]

11 minutes ago, Tex_NL said:

Use bigger docking ports. The big 2.5m clamp-o-tron is a lot stronger than the regular 1.25m. KW Rocketry contains an even stronger 3.75m docking port.

Have the undocking bugs been fixed? I learned the hard way that the 2.5m ones at one point no longer have an "undock" option and tend to use them only for putting things together that are not supposed to be decoupled (ie. space stations). But that's a behavior I picked up around .90 so things might have gotten better.

[Rocket In My Pocket]

1 hour ago, Kuzzter said:

"QUESTION to @Rocket In My Pocket -- to which orange tank surface was your "rock solid" three-port solution attached? End or side?

The end, although I'm now curious to try some ports on the side...but I'm worried that'll be even harder to dock.

[Pecan]

2 hours ago, Kuzzter said:

-- simultaneous docking to more than one point, different surfaces (e.g. one on the ship's belly, one axial)

 

I like option B - one at the front, one underneath or on top.  The trick with multi-docking is getting your orientation relative to the ports right but, given that they're going to be pretty close if you're trying at all, their magnets will be pulling them 'close'.  If the first one docks and the second isn't aligned - undock.  Magnet on number 2 will do the work and number 1 won't re-dock while it stays within the 'safe' range.  That might sound like a problem ... until you switch to KSC or another ship out of physics range, quicksave/quickload or whatever; number 1 will re-dock all on its own.  Expand concept for more than two ports ...

 

[Starhawk]

I'm really hoping to see a few more people who have tried multi-port docking in 1.0.5 wade in here with more data.

Happy landings!

[DomiKamu]

Interessing question, in particular to assemble (in orbit) stronger vessel parts.

Of course, in current (1.0.5) docking is based on ports couple actions such  "Command from here" (from your spacecraft - may be a part of final vessel) and "Set as target" (final vessel). But one port (on each vessel).

If other ports (on both vessel parts) are perfectly aligned, I don't know if this tip are working or not.

@Tex_NL: of course KIS/KAS may help for vessel reinforcements, but undocking/decoupling may be required however (e.g. additional fuel tanks jettison). Don't know about KJR but I'm looking for...

Edited December 18, 2015 by DomiKamu
Some mistakes...

[MaverickSawyer]

Personal experience with the KAS struts is that they'll sever just like stock struts upon staging or undocking... but they're reusable. Once you return, just pop on out for a brief EVA and reconnect 'em.

Granted, that was in 0.90, but that behavior shouldn't have changed much. And, as others have said, when paired with KJR, ships that used to be wet noodles become quite sturdy. I still use at least three struts across major load-bearing 0.625 or 1.25m docking connections, and use the Near Future packs 2.5 meter port. It's heavy, but INSANELY strong. Like, "the node between the docking port and the rest of the structure becomes the weak point" levels of strong.

Edited December 18, 2015 by MaverickSawyer

[radonek]

On 16. prosince 2015 22:33:52, Kuzzter said:

-- docking to a port followed by capture at a different point with the docking klaw

Afaik this is not possible. After docking to port, both crafts are merged into single vessel which never collides with its own parts. So your Klaw will be unable to grab onto anything.  Maybe it could be done other way around - grab with klaw, unlock it and let docking ports magnets do their work… even if it wont actually attach, magnets will help hold it. But it still feels kinda  krakenprone :-(

[Snark]

On Wed Dec 16 15:32:10, Rocket In My Pocket said:

The end, although I'm now curious to try some ports on the side...but I'm worried that'll be even harder to dock.

One thing that will make this lots nicer in 1.0.5: There was this bug, which had been around since forever, which 1.0.5 finally fixed. It used to be that when you chose "control from here" on a docking port, the orientation of the navball would rotate to face the right way, but the location would be wrong: it would draw things as if the control-from-here point were at the CoM.

This caused an ugly navball misalignment any time that the axis of the docking port you're controlling from happens to be offset from the CoM, which is frequently the case with side-mounted docking ports.

That's fixed now, so docking with side-mounted ports should be a lot more straightforward.

[Rocket In My Pocket]

33 minutes ago, Snark said:

One thing that will make this lots nicer in 1.0.5: There was this bug, which had been around since forever, which 1.0.5 finally fixed. It used to be that when you chose "control from here" on a docking port, the orientation of the navball would rotate to face the right way, but the location would be wrong: it would draw things as if the control-from-here point were at the CoM.

This caused an ugly navball misalignment any time that the axis of the docking port you're controlling from happens to be offset from the CoM, which is frequently the case with side-mounted docking ports.

That's fixed now, so docking with side-mounted ports should be a lot more straightforward.

Never used control from here or the navball for docking, as I tend to just eyeball everything once the two ships are within physics bubble range, but that's an interesting point!

I was more concerned about the tendency of docking to one port making other ports that are close by not dock appropriately, this can require some undocking and redocking of different ports even when they are all on the same surface.

My gut feeling is that docking 2 pairs of ports on 2 differently facing surfaces (Ie. A pair on the side and another pair on the end to make a sort of "L" connection) may be even more troublesome, but I don't know for sure.

[Starhawk]

So, I've come up with a design and done some preliminary testing.  So far, it looks like a success.  The system is comprised of a Mk3 spaceplane cargo bay and a size two (2.5 m) explorer/lander.  The lander has four Jr. docking ports attached with radial symmetry and a normal docking port on the nose.  The two 'lowest' of the Jr.'s connect to the spaceplane along with the axial nose mounted port.

On each of the four test dockings so far, the lander has been pulled right into place and docked at all three ports as soon as I got close.  I made sure to be careful about my orientation, but it seems that the magnets are pretty powerful.

Terribly arrogant of me, but I call it the Hawk-dock system.

Happy landings!

[fourfa]

I have a tiny lander that stows in a single Mk3 cargo bay:

Medium size docking port at its top, small port above the lander can window. So they're mounted at 90 degrees, or an "L" as you say.  Now it's a lightweight craft, and if it moves it only bumps cargo bay walls (which are essentially transparent to collision somehow).  But I've had no problems, it locks itself in place very easily and securely, and undocks with no drama.

[Mister Dilsby]

L-dock worked for me also. Key was to get everything aligned before launch in the VAB using the Merge command to put the spaceplane next to the docking assembly. Note that since both ports on the plane are shielded, you can't get a node to attach to them when trying things out--so I temporarily put a standard port aft, linked the mating assembly to that standard port, moved the ventral port around until it looked close enough visually, then saved the L-bracket subassembly and put it on the target ship (and replaced the shielded port on the plane)

The result: successful multiport dock on the first try! 

backing in... I aimed for the aft port first and trusted the ventral port to follow.

And there it is!

[Pecan]

34 minutes ago, Kuzzter said:

L-dock worked for me also. Key was to get everything aligned before launch in the VAB using the Merge command to put the spaceplane next to the docking assembly.

Congratulations :-)

[Starhawk]

39 minutes ago, Kuzzter said:

L-dock worked for me also. Key was to get everything aligned before launch in the VAB using the Merge command to put the spaceplane next to the docking assembly. Note that since both ports on the plane are shielded, you can't get a node to attach to them when trying things out--so I temporarily put a standard port aft, linked the mating assembly to that standard port, moved the ventral port around until it looked close enough visually, then saved the L-bracket subassembly and put it on the target ship (and replaced the shielded port on the plane)

The result: successful multiport dock on the first try! 

Very interesting!  Nice to see you got it on the first try, too.

My only problem now is that I can't figure out whether or not to upvote your answer to your own question!

Happy landings!

[Andersenman]

For a mod smaller than KAS, Quantum Struts is being Continued and seems to be up-to-date and working. While these are technically wizardry, their use can be justified with parts that look like structural support without actually needing to be that.

[Vaporized Steel]

Despite it being said I do want to remind you fully about matching all alignments in the VAB. That means that the station as a whole fits together, and all it's sections are preferably seperated into subassemblies to put on top of your launcher. And all subassemblies can be re attached from scratch into a wholesome station.

Failing in this or re-offsetting, re-adding or removing anything can offset one of the ports or the Com and you don't want that. And by the time you find out your in space with 2 unequal modules.

You also mention that your motive for multiple docking attachments is the wobbling during transfer burns.
If you are willing to use mods you can use KAS Kerbal attachment system

 

The mods speaks for itself and is mentioned before. Anyway, there are mobile parts in there, a Kerbal can carry struts which he/she can attach to prepositioned attachment point on one side of a module to prepositioned strut attachment parts of another docking craft, this can be done in space to strenghten joints and stop wobbling alltogether even with 1 docking port connection. Requires a kerbal near the vessel.

It's a somewhat better more realistic alternative to Kerbal joint reinforcement mod, besides you can use the mod for a whole lot more then strutting in space :=)

If it's the angle snapping from one port to another then there are docking ports that let you control angle snapping in space. It's something I needed and asked about lately and was recommended the Kip Engineering Androgynous docking ports mod. But I don't think You'll need that perse.

Anyway, combining these 2 mods not only strenghten joints but also may make things look more symmetricall. So you'll also win on the aesthetics if you care about that.
 

Edited January 6, 2016 by Vaporized Steel