Based on this video that shows players walking on a flying platform, if you look closely you can see that Core Unit is not directly connected to the construct, it is hovering just below it. This indicates that having disconnected parts of a construct does not influence the behavior of the construct. When forces are applied to the construct as a whole, and disconnected parts will still move with the whole.
Bearing in mind that this is a pre-alpha build, it seems that this is something that should be changed soon, and I would hope that the dev’s are planning on it. Allowing the different parts of a construct to be completely disconnected from the core unit, and other parts of the ship for that matter, will lead to some strange designs and exploits, not to mention being unrealistic. In a game like space engineers when building the disconnected piece would go floating off, but since severing pieces in DU doesn’t create a new construct this won’t happen. This can be avoided during construction by making it so that when you delete a segment that connects a part of the ship to the core unit, the now disconnected section is also deleted.
This also has implications for combat and destruction, where it seems that severing parts of a construct would be a pretty common occurrence. Personally, I’m okay with there being, severed parts moving along with a construct after it has been damaged. Ideally however, this debris would float off / or despawn after being detached from the ship. This would require them to be considered a separate construct, but they would lack a core unit. Hard to know whether that it is feasible though. Thoughts on this topic?