Advanced Adhesion Model Issues

[t_rail]

I experimented with the advanced adhesion model for my locomotive. I also examined the code and noticed some issues, which maybe should be improved:

1) Sometimes OR uses too high axle inertia without the possibility to influence it:
e.g. locomotive of 80t with mass factor 1.3 and wheel radius of 0.6m
-> should result in: 80000kg*(1-0.3)*0.6m^2 = 8640 kgm^2
Entering this value as orts wheel inertia parameter will be ignored because it is below 10000kgm^2.
OR's own calculation leads to a result of about 16000kgm^2 -> too high

2) The calculation of the wheel rotational acceleration does not involve the wheel radius. It should be:
rotational wheel acceleration = sum of axle forces * wheel radius / axle inertia
but it is
rotational wheel acceleration = axle force / axle inertia
leads to wrong unit 1/(s^2*m) instead of 1/s^2

3) The advanced adhesion simulation has a much higher dynamic, so it needs smaller step-sizes.
Therefore the axle subsystem should be divided into minor steps. Currently the model seems to run with the same step-size as the main simulation. This results in oscillation of the tractive force, even if the random adhesion option is turned off.

4) In OR the wheel slip characteristics function converges to zero for high wheel slip speed, but it should converge to the slide friction coefficient.

5) If the train's speed is zero, OR does not model slipping wheels, although the maximum sticking friction is overcome.

6) The brake force of the locomotive is used twice ("Car.cs" and "Axle.cs") to brake the locomotive
-> brake force may be twice as much

7) For the advanced adhesion model the rolling friction force should be added as moment on the axle instead of adding it to the car (but won't have much influence).

Would somebody please confirm or clarify a few of the items? Otherwise i will try to fix it with patch files.

Thanks & best regards

[steamer_ctn]

I experimented with the advanced adhesion model for my locomotive. I also examined the code and noticed some issues, which maybe should be improved:

.................................................. .....

Would somebody please confirm or clarify a few of the items? Otherwise i will try to fix it with patch files.

I am currently adding some functionality to the adhesion model to cover steam locomotives, as the model was originally built only for diesel and electric locomotives.

So it would be good to co-ordinate any changes.

If you are interested in collaborating on adjusting the model(s), then let me know.

Cheers

[t_rail]

Thank you for your offer. Yes, i am interested in improving, fixing or discussing models.
To solve some of my mentioned issues, i think it should be sufficient to adjust "Axle.cs" and extend "Integrator.cs".

Cheers

[steamer_ctn]

Thank you for your offer. Yes, i am interested in improving, fixing or discussing models.
To solve some of my mentioned issues, i think it should be sufficient to adjust "Axle.cs" and extend "Integrator.cs".

I will PM an email address so that we can discuss potential changes.

[ftldave]

I am currently adding some functionality to the adhesion model to cover steam locomotives, as the model was originally built only for diesel and electric locomotives.

Is that really true? I've found electric locomotives to be all but impossible to run in OR, requiring way too much throttle to start motion and then unable to get any speed. The original MSTS Acela, Just Trains' TGV, pretty much anything with a pantograph doesn't run right in OR, unlike most diesel engines.

[steamer_ctn]

Is that really true? I've found electric locomotives to be all but impossible to run in OR, requiring way too much throttle to start motion and then unable to get any speed. The original MSTS Acela, Just Trains' TGV, pretty much anything with a pantograph doesn't run right in OR, unlike most diesel engines.

As I understand it, as far as the code is concerned the functionality is "in place", whether it is working or not in the game, I cannot say for certain.