How do docking ports work when they are connected during a build?

[tepid]

Hi all, I just created an account here to post this question so I apologise if it's not in the right place or formatted correctly etc.

I am trying to do my first Mun landing in Career on Normal. I wanted to do an Apollo-Style mission where my lander is docked to a command module and re-docks after Munar landing and ascent.

I couldn't quite remember how Apollo did it so I ended up placing docking ports on my lander and CM and connecting them up in the builder, so the lander was upside down. I'm not sure how to post a picture since I'm on console and posting here from mobile, but I think you'll get the picture. Fast forward and I manage to build my biggest and most complicated rocket ever, the launch goes surprisingly well and I'm in low Munar orbit with plenty of delta-v on each craft.

I messed up the staging as the port was one or two stages up from my CM engine and I didn't want to risk messing it all up, so I tried to manually undock the ports. It would only let me highlight and bring up the context menu for the CM port. There was no 'undock' option, only a 'disable docking node' or something to that effect so I selected that. Something went wrong as the craft would not seperate and were ocsillating very weirdly (my scientist had transferred over, the lander had SAS enable and a probe core on it so control wasn't the issue, it just moved the CM as well). I reloaded, moved the staged port down below the engine and staged and the same thing happened.

 

I reloaded to a quicksave halfway to the Mun and adjusted my trajectory to a free return to Kerbin. When I got there I manually activated the decoupler below my CM so I ended up with the Mk2 command pod and a lander docked above it. Curiously, when I got to about 30km and the rest of the lander had exploded (only a lander can attached) I found that the docking port had an 'undock' option and it worked, thus leaving me with just the command pod and able to activate the chutes, and land safely.

Can anyone give any insight as to why this happened? I assume it's something funky happening with the fact that they started off docked but I didn't imagine that should create any issues. I'm going to tweak the whole thing to make it more accurate to Apollo 11, where my lander is stored beneath the CM and I flip the CM, dock to and extract the lander en route to the Mun, but I was just curious where I went wrong.

Also, any build tips for pulling off the above? I haven't started yet but can't quite figure out how I'm going to configure the craft correctly. Do I need to attach the lander to the stage below or will it just sit within the fairing/assembly? How do I make sure I can extract it once the CM is docked? Many thanks and sorry for such a long post.

Edit - think I figured out the lander stuff. Lander is attached by the port to a decoupler attatched to CM engine. Once in orbit decoupler below lander is staged, and the CM and lander decouple via custom action group (just to make the staging abit simpler).  From there flip around, dock the two craft, and do Trans-Munar injection burn. Hopefully there won't be issues with the ports not handling the acceleration? Can't imagine so.

Very excited as this is the craziest build I've done so far and it seems like it's going to go well. Never thought I'd get here, up till now the most advanced things I've done on my own are returning science from low Munar orbit and rescuing a Kerbal from a pretty crazy inclined Munar orbit. I'd never even used any parts bigger than the 1.25m ones. Now I've got a pretty stable 155 ton, 32.5m tall rocket that can comfortably put at least 13tons of payload into a high Kerbin orbit.

Tutorials help of course, big thanks to these forums and Mike Aben over on Youtube. That guy's the best.

Edited August 31, 2023 by tepid

[Vanamonde]

It sounds like you may have encountered the occasional bug in which you've done things right but the docking rings function inconsistently. It's happened to everybody once or twice but fortunately is not common. 

[king of nowhere]

14 hours ago, tepid said:

Hi all, I just created an account here to post this question so I apologise if it's not in the right place or formatted correctly etc.

I am trying to do my first Mun landing in Career on Normal. I wanted to do an Apollo-Style mission where my lander is docked to a command module and re-docks after Munar landing and ascent.

I couldn't quite remember how Apollo did it so I ended up placing docking ports on my lander and CM and connecting them up in the builder, so the lander was upside down. I'm not sure how to post a picture since I'm on console and posting here from mobile, but I think you'll get the picture. Fast forward and I manage to build my biggest and most complicated rocket ever, the launch goes surprisingly well and I'm in low Munar orbit with plenty of delta-v on each craft.

I messed up the staging as the port was one or two stages up from my CM engine and I didn't want to risk messing it all up, so I tried to manually undock the ports. It would only let me highlight and bring up the context menu for the CM port. There was no 'undock' option, only a 'disable docking node' or something to that effect so I selected that. Something went wrong as the craft would not seperate and were ocsillating very weirdly

 

with docking ports, the most common issue is them being attached on the wrong end. but your port evetually worked, so it's not the issue here.

other times docking ports just get stuck for no reasons. kml editor can fix that

Edited August 31, 2023 by king of nowhere

[tepid]

3 hours ago, Vanamonde said:

It sounds like you may have encountered the occasional bug in which you've done things right but the docking rings function inconsistently. It's happened to everybody once or twice but fortunately is not common. 

Ah, thanks for the response. That would suck since it led to me changing my whole build and it took quite a while. Anyway, I managed to land on the Mun and get back with a ton of science. On to Minmus!

[tepid]

1 hour ago, king of nowhere said:

with docking ports, the most common issue is them being attached on the wrong end. but your port evetually worked, so it's not the issue here.

other times docking ports just get stuck for no reasons. kml editor can fix that

Thanks for the response. I'm on console do I don't think I have access to things like that. Either way, it's just good to know that the ports are able to be built docked together and then undock after launch. I just assumed that wasn't possible

[king of nowhere]

1 hour ago, tepid said:

Either way, it's just good to know that the ports are able to be built docked together and then undock after launch. I just assumed that wasn't possible

not only it's possible, but as far as i can tell it has no relation to whether the docking ports get bugged.

on the downside, if they do get bugged (it happened two or three times to me in 3 years of playing) and you can't use kml editor... i'm afraid you'd lose the whole ship.