That's good Mate.
I'm going to use your barrage ballon as the perfect example to follow along with.
(If you don't mind)
You have 3 parts on that model that are the same.
The fins.
Each is the same from images I see posted here.
When you load that model into any SH version?
All 3 get loaded into memory at one point or another because it's one 3D mesh.
Now, if we only load one fin into the dat you've lost alot of overhead on loading.
How do you think SH Games can reproduce many Ship with only one simple model?
It's called instanceing.
We create not a new 3D mesh but an instance of an existing 3D mesh.
So for the barrage balloon?
Only one fin is in the dat file.
We create the other two by instanceing it in that dat file and rotating thier positions.
Now I know your lost, correct?