steamer_ctn, on 02 March 2016 - 01:34 PM, said:
If so, friction relies on the Davies co-efficients multiplied by the speed of the train. The Davis co-efficients are calculated externally to OR, and they do take into account the mass of the wagon (but only a full or empty wagon scenario). Therefore, for the main friction calculations (and possibly freight animations), variable weight is not considered at this time, but is fixed at the value of the Davies co-efficients in the WAG file.
To adjust the friction values for a wagon with a changing mass, the full suite of Davies formulas would need to be incorporated (and this wouldn't allow for some freelancing by modellers with different Davies co-efficients) into OR, with a means to differentiate between the different wagon types.
Alternatively, perhaps the full and empty Davis co-efficients could be included in the WAG file, and a sliding calculation done between these two limits to adjust the friction with a changing mass.
I have always believed the OR software should be computing the Davis formula(s) using the elemental parameters in the .wag file AND NOT as it is now, being calculated by FCalc and holding the results. As far as multiple Davis Formulas, surely it would be easy enough to use a Case Statement to select among the several variations as chosen by either the end (via the options page) or perhaps by the car/locomotive designer (via a code selection in the .eng or .wag). These could be identified by year or by recommending party (e.g., something like "The 1945 Davis formula"). People who care about the difference can pick one, everyone else can accept whatever is the default in the program.
FWIW, It would also be (IMO) advantageous for .wags and .engs to use EmptyMass() and LoadedMass() with the ultimate expectation that LoadedMass() would ultimately depreciate in favor of LadingMass() where LadingMass() is kept outside of the .wag or .eng -- IOW either in the consist file one of the or Activity files.