Editing SFS file to switch part order

[Montag]

Houston, we have a problem. It seems those pesky rocket designers had too much to drink and switched the order of two parts and we are asking for Divine intervention to correct the problem. From the images below you can see the TR-XL Stack Separator (stackSeparatorBig) and Docking Port Sr (dockingPortLarge) are reversed. I am sure I can complete the mission and just have the LV-909 Terrier burn off the Docking Port Sr after separation, but I would rather leave the docking port intact on the science lab portion. I intend to keep the Science lab in orbit. It would still have the Docking Port Sr at the other end, but this is a chance to fiddle. I know I need to address the solar / strut clipping, but I will do that later for new builds.

Broken

Fixed

From the SFS file which has the "broken" vessel has the following relevant parameters:

probeStackSmall (item 0) is my root part
attN = top, 74 (attachment node top is part 74 - stackSeparatorBig)
position 0,0,0

stackSeparatorBig (item 74)
parent = 0
attN = bottom, 0 (attachment node bottom is part 0 - probeStackSmall)
attN = top, 75 (attachment node top is part 75 - dockingPortLarge)
position = 0,0.19999885559082,0

dockingPortLarge (item 75)
position = 0,0.299999237060547,0
parent = 74
attN = top, 76 (attachment node top is part 75 - liquidengine3)
attN = bottom, 74

name = liquidEngine3 (item 76)
parent = 75
position = 0,1.06281852722168,0
attN = top, 77
attN = bottom, 75

Can I get away with just changing the parent, attN = top, attN = bottom parameters - switching 74 with 75, and position?

Does the order of the Part { } matter within a Vessel { } as long as the numbers are correct?

Is the position the center of the part or is it the face of contact with its parent? - Trying to figure out what the position parameters would be when switching the separator with the docking port. I cannot find the actual part heights.

Edited June 30, 2015 by Montag

[Warzouz]

- Make a backup of your persistent.sfs

- Go to the VAB and reload you craft.

- Correct it.

- Put it on the launchpad

- Then edit you SFS file.

You must locate the parts of the two ships, compare those parts and copy paste the two parts. There are several identifier (ship reference, parent part...) you must check them and get the correct value.

I used this technic que add a docking ring on a space station (I put is one the wrong side and it stayed on the transfert stage/debris...

[Zephram Kerman]

Warzouz answered your question directly, but a more fun way might be to get KAS and have Bill go EVA to do the repair manually. It's traditional that kerbals would notice a mistake only after launch, and then fix it in orbit.

[Warzouz]

I used KAS to remove a lot of parts (250 out of 900) on an old space station tu reduce lag. I don't think you can swap parts like decoupler and rings (maybe the smallest one ?)

[Montag]

I was planning on doing the VAB and Launchpad analysis but posted from work yesterday. I did do the study and successfully reversed the part order by editing the persistent file. I did cut and paste the part { } sections so that they were in the sequence on the vessel { }. I do not know if that mattered or not.

[Warzouz]

You can test it, but

1- There are some ID (part, ship, parent) you should check

2- There latbe some coordinates for attachement, no ?

Don't forget to backup de file before.

[Montag]

I successfully made the edit last night.