[Csantucci]

The Z component of the CentreOfGravity parameter in .eng and .wag files is used by OR to position the trainsets on the track. First question: why is it used, instead of the parameters in the .sd file? Accordingly to the MSTS official documentation, the CentreOfGravity is what its name suggests, that is the center of gravity of the trainset, which not necessarily coincides with the center of the wagon.
Second question: in the OR code there is a check: if such Z component is higher than 1 or lower than -1 in the .eng or .wag file, it is reset to 0. Why?
I raise these questions because someone showed to me some trainsets that couldn't be properly aligned, because they needed a Z component outside the -1 to 1 range. Once I increased the allowed range in a test ORNYMG version, the trainsets could be properly aligned.

I'm not an expert in this field, so maybe I'm overlooking something.

[pwillard]

Particularly in ORTS, I don't recall CentreOfGravity being particularly critical for model *placement* as the MODEL coordinates inside the S file would define the height above the track. I was pretty sure this value was NOT related to model placement and was more about friction and derail calculations until you posted this. Maybe I'm wrong?

[ATW]

I notice COG does a difference in visual on Z as in length alignment, it does a difference for curve speeds but no visual differences for Y that the higher the height the more vulnerable to derail in the curve speeds but not for stringline yet and last but not least X does nothing really or the thing I expected it to do someday.

You would think X can be used as a visual purpose and curve negotiation speed for poor stock representing shifted loads leaning depending where Y and Z judge the center.

[Csantucci]

I am talking here only about the Z component and, yes, it affects the longitudinal displacement of the trainset.

[slipperman]

Hi,
This is from : https://msts.steam4m...als/length.html

Quote

you still may occasionally notice that wagons are not equally spaced when one wagon is flipped relative to its neighbour. The couplers may be further apart or more bunched up than when all the wagons are "facing forward" or unflipped. This occurs when the model is not centred on the Z-axis and thus the couplings are not equally spaced when the car is flipped.

In MSTS, I understood this to be one of the most important uses for the Z value of CentreOfGravity. I do not know if it's required to the same extent in Open Rails.

Cheers,
Ged

[pwillard]

This whole thing points to dealing with a faulty model, no?

[Laci1959]

pwillard, on 31 July 2023 - 09:09 AM, said:

This whole thing points to dealing with a faulty model, no?

HELLO.

If it was just a faulty model, that would be fine. But unfortunately there are more of them. MSTS had a Center ( X Y Z ) entry in the Wagon section. I think it moved the physical Pivot point of the model virtually.
American base models didn't need it.
Perhaps it should be introduced, even under the name ORTSCentre. No length limit.
But ESD_Bounding_Box would also be nice. The lack of this is evident elsewhere.

Sincerely, Laci 1959

[ErickC]

I agree - it would be one thing if it were one or two models here and there, but the vast majority of models built before around 2010 or 2012 sit on the rails wrong. It seems kind of silly to retire almost the entire SLI fleet for being buried in, or floating above, the rails, when the models otherwise look just fine.