We suggest making a few modifications to the systems definition introduced in CPACS v3.5.
Pre-defined elements
For the pre-defined systemElements, we propose updating the geometry definition.
The changes introduce simplified primitives and extensions such as multiSegmentShapes and external CAD linking, which are described in detail in #848 (comment)
Aircraft level
In vehicles/aircraft/model/systems/genericSystems/genericSystem, we propose removing scaling from the component placement concept.
The main reason is that the physical implications of scaling are not sufficiently clear, particularly with respect to mass, center of gravity, and inertia properties. We therefore propose following a stricter rule: if a component of a different size is required, it should be defined as a new pre-defined systemElement rather than obtained by scaling an existing one.
This keeps the semantics clearer and avoids ambiguous interpretations in downstream weight-and-balance workflows.
Open point
One important open to-do is to provide a better structured and more explicit list of element names (batteries, compressors, etc.), ideally grouped by thematic clusters. A working group in the EXACT project is currently preparing a proposal for this.
Implementation status and next steps
As discussed in #848 (comment), the proposed changes have already been implemented and tested in a prototypical TiGL implementation:
DLR-SC/tigl#1283
We suggest targeting CPACS v3.5.1 for these adjustments. This would make it clear that these changes refine the systems definition introduced in CPACS v3.5, while also aligning with the corresponding functionality planned for the next TiGL v3.5 release.
We suggest making a few modifications to the systems definition introduced in CPACS v3.5.
Pre-defined elements
For the pre-defined
systemElements, we propose updating thegeometrydefinition.The changes introduce simplified primitives and extensions such as multiSegmentShapes and external CAD linking, which are described in detail in #848 (comment)
Aircraft level
In
vehicles/aircraft/model/systems/genericSystems/genericSystem, we propose removing scaling from the component placement concept.The main reason is that the physical implications of scaling are not sufficiently clear, particularly with respect to mass, center of gravity, and inertia properties. We therefore propose following a stricter rule: if a component of a different size is required, it should be defined as a new pre-defined
systemElementrather than obtained by scaling an existing one.This keeps the semantics clearer and avoids ambiguous interpretations in downstream weight-and-balance workflows.
Open point
One important open to-do is to provide a better structured and more explicit list of element names (
batteries,compressors, etc.), ideally grouped by thematic clusters. A working group in the EXACT project is currently preparing a proposal for this.Implementation status and next steps
As discussed in #848 (comment), the proposed changes have already been implemented and tested in a prototypical TiGL implementation:
DLR-SC/tigl#1283
We suggest targeting CPACS v3.5.1 for these adjustments. This would make it clear that these changes refine the systems definition introduced in CPACS v3.5, while also aligning with the corresponding functionality planned for the next TiGL v3.5 release.