Thoughts on Weight&Balance node revision from the point of view of flight mechanical analyses

[MarAlder]

Thanks @HHOPs for your thoughts on #766 and for the permission to put it here translated so that we have all discussions available at GitHub (names and project specific information removed; machine translation):

• My current approach considers for flight dynamics modeling and analysis (open- and closed-loop) one associated weight & balance case each for OWE, CoG and inertias. The fuel mass fraction serves as the initial value for continuous integration / defueling based on the engine map (mDotFuel). Thus, mass and CoG are continuously tracked - inertia is considered "constant". Further, discrete mass events can be triggered (manually, for lack of mechanism)....
• I work - in the context of the "Fuel-Sloshing" topic on a flexible, internal mass model, which is fed if necessary from the mass-breakdown of the single components (structure, systems and cont./discrete changing components) and then is calculated accordingly ("Steiner"-shares etc.). The background to this is that it will thus be possible to hook in quasi-static, but also dynamic models with different approaches ("fuel sloshing") for individual components (esp. wing and fuselage tanks), and thus directly map the effects on flight dynamics, FCS, etc. I would of course like to link this mechanism to CPACS....
  Weight & Balance in this context would then be seen more as an "indication/result" for extreme situations or certification requirements etc., as well as for balancing against the detailed approach
• So the connex is:
  o Base masses & consumption masses at their respective positions.
  o Consumptions (by SFC) / drops etc.
  o Temporal (and if necessary spatial) sequence of changes
• What would be helpful in this on the CPACS side:
  o On the one hand, a detailed description of the structural masses and components (mass, CoG, inertias).
  o Documentation of the properties of these components (static, if necessary internal displacement without mass change (LDG, Trim-Tank, High-Lift, ...), drop (discrete), consumption/refill (continuous))
  o Initial fill levels of tanks (associated with a WaB case); and
  o Changes occurring during the mission (refueling and defueling strategy, refueling quantity if applicable, dropping loads from fixed positions - drop tanks / effectors, moving components - pallet drop, etc.).
• If the "triple jump": masses -> application -> WaB is still of interest for others, one could consider to pack this possibly into a small tool / library...