When the "envelope rep" of an assembly is active and a user goes to the "model properties" menus to view mass properties, those mass properties properly reflect those of all the components the envelope part was defined to represent. HOWEVER, if I run mass properties analysis... the envelope "becomes a normal" part and shows ITS volume times density as the mass and CG location!
that degrades the utility of envelopes to being strictly visual in any and all higher assemblies! The mass properties of envelope parts should be "full-assigned" and driven by the components they represent. Below are two very common (for many customers) use cases:
Case 1: The actual assembly (that defines the envelope) is used higher assemblies.
If my rocket has 200 fully-detailed electronic box assemblies assembled to it, most users and most daily purposes are properly accommodated by retrieving a higher level assembly rep that shows the envelopes of all boxes. Each one being simple "boxes" representing an approximate "spaceclaim".
Why should the mass properties people and dynamic analysis people need to include all internals of all boxes to get correct mass properties?
Case 2: Even more common.
Different vendors, many using CreoP, are responsible for designing the electronic boxes we use. We gain no value (and a lot of performance degradation) if we were to ask them to deliver the fully detailed assemblies. In fact, almost all vendors would refuse to do that anyway.
They should be able to deliver THEIR envelope models to us (at what ever level of detail we mutually agree on)... and they should come with their "fully-assigned" mass properties so that we can use them for: