Bug #25925
A fairing closed on the part attached to its top node or an interstage node breaks the node connection when deployed
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Description
I'm not quite sure how to describe this. Create a fairing, enable interstage nodes. Place something appropriately shaped on top of an interstage node. Build the fairing and close it around the object on top. Then launch and deploy the fairing. The object drops, as if it's been decoupled.
What's doubly weird is that the object has not in fact been decoupled! It's still part of the vessel: it doesn't interact with the rest of the vessel unless same vessel interaction is enabled, you can still access all the options in its PAW, its position affects the vessel's CoM, etc. But it seems to move independently.
The bug does not occur if the fairing is closed on an object other than the one attached directly to the interstage node.
Attaching a craft that demonstrates this effect using an SRB. Move it to the stage after the fairing to see it drop through the craft, or leave it as is to see it launch into space while remaining "landed" at the launchpad.
History
#1
Updated by dok_377 over 3 years ago
Updated by - Platform Windows added
Happens on Windows too. And it has nothing to do with the interstage nodes, the main one does the same.
Directly related to #21915, as it contains the same workaround. If the root part ISN'T ON THE SAME STAGE AS THE FAIRING - the bug will not occur.
#2
Updated by arctangent over 3 years ago
Updated by Yep, you're right. I did see #21915 but I filed this as a separate bug because there are no decouplers involved, though it may well be another manifestation of the same underlying issue. Sure enough, if the root part is on the "stage" above the fairing rather than below it, the issue doesn't occur.
#3
Updated by arctangent over 3 years ago
- Subject changed from Interstage fairings break connections when deployed to A fairing closed on the part attached to its top node breaks the node connection when deployed
#4
Updated by arctangent over 3 years ago
- Subject changed from A fairing closed on the part attached to its top node breaks the node connection when deployed to A fairing closed on the part attached to its top node or an interstage node breaks the node connection when deployed
#5
Updated by dok_377 over 3 years ago
It needs to be a separate issue because it is a separate issue, it just has some things in common with the old ones. It might as well just be a byproduct of the old ones. I suspect that the new features unfortunately were coded on top of already bugged code, which is not great at all. It will be considerably more difficult to "untangle" if that's the case.
#6
Updated by arctangent over 3 years ago
This bug appears to have been introduced in 1.10.0 - I checked a copy of 1.9.1 that I still have and the issue doesn't occur there.
I wonder if this one was caused by the attempted fix that's mentioned in the 1.10.0 changelog?
#7
Updated by dok_377 over 3 years ago
Most likely. They've changed quite a bit with the fairings in 1.10 release, so no wonder some stuff snuck in unnoticed.
#8
Updated by XanatosX over 3 years ago
Updated by 
I think I did find the problem as well and did take a Video of it: https://www.reddit.com/r/KerbalSpaceProgram/comments/jdcm04/question_is_this_a_bug/
I did some testing and seems like this problem only appears if you fully close the fairing. If you leave a small space empty and close ith with alt + left click it is working, this is not really a solution or a good workaround but maybe it helps to detect the problem.