Connecting Multiple Docking Ports

[maddog59]

I've built two identical ships with multiple docking ports - my idea was to link them up in orbit by having two of the ports on each ship aligned and locked together. I was able to get them together, and with one pair of ports docked (the bottom pair), but the second pair (the pair near the top), although they LOOK aligned, just aren't locking together. There seems to be enough play between the two ships to get them to line up, but all they do is pass thru each other. Any suggestions on how to get them together?

 

[Reactordrone]

As I understand it you can't have loops in vehicle construction  so only one set of docking ports can attach.

[maddog59]

14 minutes ago, Reactordrone said:

As I understand it you can't have loops in vehicle construction  so only one set of docking ports can attach.

Sorry, could you clarify what you mean by 'loops'?

[Spricigo]

1 hour ago, maddog59 said:

Sorry, could you clarify what you mean by 'loops'

You cannot attach a craft to itself. Since the is already a link between the first pair of docking ports (and a chain of connection to each port in the second pair) the second pair will not connect.

Struts are the exception.

 

 

[vv3k70r]

8 hours ago, maddog59 said:

There seems to be enough play between the two ships to get them to line up, but all they do is pass thru each other. Any suggestions on how to get them together?

Servo under docking port - when You attach one rotate the ship. You can force the aligment by other construction parts against tanks itselfs - You can bind them to side docks and they gonna stick cocertly whatever the direction in right hemisphere.

Samller the craft, or more docking ports would force the aligment easier like a zipper.

8 hours ago, Reactordrone said:

As I understand it you can't have loops in vehicle construction  so only one set of docking ports can attach.

No.

5 hours ago, Spricigo said:

You cannot attach a craft to itself.

Yes You can, here is axample I'm using:

https://steamcommunity.com/sharedfiles/filedetails/?id=2282142667

[jimmymcgoochie]

Have you tried enabling same vessel interaction on the two ports you want to connect? You might also be interested in the ReCoupler mod, though I don’t know if it can fix this type of thing, or using an automated docking system (e.g. MechJeb) with the alignment tightly set so both sets of ports are precisely lined up before docking.

[AHHans]

16 hours ago, Reactordrone said:

As I understand it you can't have loops in vehicle construction  so only one set of docking ports can attach.

That is correct, but you still can have two craft connected via multiple docking port paris. In this case one connection becomes the primary one (which defines the craft tree for those who know what I mean by that), and the others become secondary connections - I guess they work essentially like struts. That's how my Nauvoo Station is built.

16 hours ago, maddog59 said:

I was able to get them together, and with one pair of ports docked (the bottom pair), but the second pair (the pair near the top), although they LOOK aligned, just aren't locking together.

As stated above: it is possible to have two craft docked together at two points. But from the screenshot I would say the the top pair of docking ports is not aligned, there is a clear offset between the two ports. So in order to have both pairs connect, you have to either align both pairs perfectly while docking or align them afterward, e.g. with rotating servos. For my Nauvoo station I got around this by using SAS to keep the two craft aligned so that I only hat to watch the relative rotation myself.

On another note: once one connection is made then the two craft become one, so collisions between the different parts are no longer evaluated and the parts can freely clip through each other - unless you have "same vessel interaction" activated.

[Spricigo]

9 hours ago, vv3k70r said:

Yes You can,

Not in the situation @Reactordroneand I were referring to: in vehicle construction (VAB/SPH).

If that is what the OP is doing, as pointed out:

29 minutes ago, AHHans said:

then the two craft become one, so collisions between the different parts are no longer evaluated and the parts can freely clip through each other - unless you have "same vessel interaction" activated.

 

[maddog59]

Thanks to everyone for your suggestions and comments. You've given me some ideas so I'm going to keep messing around with it. So far, I've been successful with a single docking port, then sending out an engineer to use KAS bars and sockets to lock things up, but I'd like to have the knowledge/skill of using multiple docking ports as I've described. Much obliged to all!

[Linkageless]

I've had more luck with much closer pairs of docking ports.  My usual system is to have a pair of Clamp-o-tron Sr. side by side, mounted on the smallest Rockomax tanks.  Even these need care to align when docking, but it's nice and robust once docked.

Being at apoapsis in a high orbit helps lots, both vessels can be pointed prograde, normal or radial and won't be greatly twisting relative to each other.  If that's not an option, perhaps pointing them both radial will be the stablest attitude.

One thing that doesn't seem to have been mentioned, and possibly isn't the case here - beware that once a pair of ports are undocked they need to be backed away a few meters before they'll attract again.

[vv3k70r]

On 11/11/2020 at 6:07 PM, Spricigo said:

Not in the situation @Reactordroneand I were referring to: in vehicle construction (VAB/SPH).

Of course I'm building it in VAB/SPH - eherever else can I build?

I have example of vehicle direct from SPH on steam worskop - it didnt work with one port. It is why I came with a second one to see if it will do. And it does.

As cosequence I did decopled it on orbit and coupled back to see if it gonna wokr. And i does.

I had same concerns as You (because of same reason), but I put it to the test. It works.

 

 

[Spricigo]

3 hours ago, vv3k70r said:

I have example of vehicle direct from SPH on steam worskop

you have a example of a craft with a 2nd pair of docking ports.

 

...just those ports are not connected. We can clearly see how those ports are clipping thru each other 

Spoiler

 

 

[vv3k70r]

On 11/14/2020 at 7:07 PM, Spricigo said:

you have a example of a craft with a 2nd pair of docking ports.

And when You place it on landing site both are conected.

 

On 11/14/2020 at 7:07 PM, Spricigo said:

...just those ports are not connected. We can clearly see how those ports are clipping thru each other 

What we see is wrong, because if You remove this port (and so it would not be connected) it dosent fly.

So - it is conected. I do not state questions why, how - it works. Thats it = job done.

I was suspicious it shouldnt work reasoning same way as You, but I test it and i was wrong. I gues there is some threshold in placing that cover part conection. It generates kraken if You move part (wheels) apart so they touch some "soft" conection (like wing). Tresholds generrate Kraken. It is common problem in aproximation for cad/cam in inustrial aplication.

[Spricigo]

14 hours ago, vv3k70r said:

And when You place it on landing site both are conected.

You are still missing the point: What happens after someone hit    has nothing to do with my comments (or Reactordrone's for that matter). That is not construction mode.

 

15 hours ago, vv3k70r said:

I was suspicious it shouldnt work reasoning same way as You

I'm well aware of how multiple docking ports behave, but given that @AHHans explained in the post right before mine (and did it very well) I didn't bother to explain it myself.

If I had to guess, I'd even follow his bet that it is a 'strut-like' connection and that is how it is meant to work, but truth is neither of us is aware if is a glitch or the intended behavior of 'secondary' docking ports. 

15 hours ago, vv3k70r said:

because if You remove this port (and so it would not be connected) it dosent fly

No surprise, is a series of weak joints.

Unfortunately that is far from the only issue with the craft: the terrier engine and the nosecone  have open nodes that generate a lot of drag, all those struts, landing legs, batteries and RCS thrusters also cause drag, the RCS thrusters are not aligned with the control axis, a single pair of control surfaces responds to yaw, roll and pitch, it have a lot more fuel than need to his stated purpose and the whole procedure seems quite complicated.

You may be satisfied on how it works but we may offer several suggestions on how make it work better. Ask if you are interested.

[vv3k70r]

5 hours ago, Spricigo said:

Unfortunately that is far from the only issue with the craft: the terrier engine and the nosecone  have open nodes that generate a lot of drag, all those struts, landing legs, batteries and RCS thrusters also cause drag, the RCS thrusters are not aligned with the control axis, a single pair of control surfaces responds to yaw, roll and pitch, it have a lot more fuel than need to his stated purpose and the whole procedure seems quite complicated.

It was cheapest avilable solution for the tech I had.

Axis aligned RCS have no pourpose - on most of my vesels I put now only one ring of thrusters to dock. It is enough.

Drag for landing vesel (it has only to deorbit) is not an issue - it has to brake from orbital speed. Most of my curent vesels have single pair of control surfaces - there is no need for more.

This rocket dosent fly up with deorbiter - it dock it in orbit only to get down. Rocket fly on its own. When I build it I had a problem with pinpoint landing from orbit - this issue dosent exist today. So the whole idea was to dock wings to the rocket for landing and I found how can I use docking port.

The whole procedure is not complicated, but now I see it unnecessary as heat shields on Kerbin (engine nozzles are good enough). I dont bring wings to space any longer.

I do not get point about fuel - rocket will come back from space almost empty. Just anough to touch the atmosphere periapsis. It will afect COM.

5 hours ago, Spricigo said:

You may be satisfied on how it works but we may offer several suggestions on how make it work better. Ask if you are interested.

Best solution I found is not to do this. But on the begining I didnt know its stupid. There is no reason to do this better, just dont do that. After testing it works I never use it, I learn how to pinpoint land.

 

There is more issues with docking ports - Yesterday I found that by pressing it against grafity and undocking give unexpected burst kind a cannon.

Edited November 17, 2020 by vv3k70r