[Jonatan]

I encountered a strange phenomenon in OR that's unexplainable to me. It's been present since a few versions back and I updated to the latest unstable release in hopes it was fixed.

On ALL my steam locomotives that I've tested I've found that at close to the max speed the locomotive begins accelerating uncontrollably even with the throttle closed, often accompanied by uninterupted wheelslip messages. If I put the cutoff into a reverse position the speed slows down. I've been looking through my .eng files for some clues but this happens on all models, including steam locos by Tim Muir and Peters test atlantic.

A pair of screenshots of my own C58, the throttle is closed and the track is level but the expanded HUD shows the power output still fluctuates between positive and negative values.

https://cdn.discordapp.com/attachments/429042953755951124/1095093786629132408/Open_Rails_2023-04-10_11-04-42.png
https://cdn.discordapp.com/attachments/429042953755951124/1095093786935312564/Open_Rails_2023-04-10_11-08-48.png

The latest log file, using Tim Muirs unaltered B&O #270, it displays the same problem.

Attached File(s)

•  OpenRailsLog.txt (22.48K)
  Number of downloads: 100

[steamer_ctn]

Jonatan, on 10 April 2023 - 01:28 PM, said:

A pair of screenshots of my own C58, the throttle is closed and the track is level but the expanded HUD shows the power output still fluctuates between positive and negative values.

Small fluctuations when the throttle is closed can be explained by the inertia of the wheels, and the rotating gear on the wheels. As the wheel rotates the gear rods are either coming down to increase force on the wheels, or going up to decrease forces on the wheels.

Jonatan, on 10 April 2023 - 01:28 PM, said:

On ALL my steam locomotives that I've tested I've found that at close to the max speed the locomotive begins accelerating uncontrollably even with the throttle closed, often accompanied by uninterupted wheelslip messages. If I put the cutoff into a reverse position the speed slows down. I've been looking through my .eng files for some clues but this happens on all models, including steam locos by Tim Muir and Peters test atlantic.

In my tests with the Atlantic, it slows down over a period of time, ie the train resistance overcomes the inertia described above. If this is not the case and it is continuing to increase in speed, then please describe the test steps that you are doing with the Atlantic so I can reproduce the results (please use imperial units, as the locomotive reference material is in these units).

So the performance that we are trying to confirm is, how long it takes a locomotive to stop if it is run up to speed, and the throttle is then closed, assuming that it is on level track, and the brakes are not applied, etc?

If you have any technical articles with this type of info in it, then it would be handy to share, rather then us trying to use anecdotal information which may not be accurate.

[Laci1959]

Hello.

Many years ago, I was taken as a passenger on a steam locomotive to repair a broken barrier (crossing). I experienced such a phenomenon then, but the locomotive was pulling then. It jerked forward and backward according to the movement of the pistons. Not much, just a little. When the driver shut off the steam, it rolled smoothly. In principle, the wheels are balanced taking into account the weight of the linkage. The counterbalance is clearly visible.
Maybe it should be made adjustable somehow, but there are so many tasks to solve.

Sincerely, Laci1959

[Jonatan]

steamer_ctn, on 10 April 2023 - 10:05 PM, said:

...please describe the test steps that you are doing with the Atlantic so I can reproduce the results (please use imperial units, as the locomotive reference material is in these units).

I simply accelerate with it, and any steam engine, to the top speed and it happens. Today the CTN atlantic did not replicate the results which is odd, while others did. Random test samples today were my private Gildgrass Railway #1 and again Tim Muirs B&O 270.

I could send you my private model to have you investigate. It's a legacy MSTS .eng with some OR physics stuff grafted to it but in my experience this and others worked fine in the 1.5 stable release. Before updating to the latest unstable I ran the version that introduced your new cylinder and steam chuff FX so I could test it, this is where I believe I started to experience this behavior.



I'm not a science guy, I experience a bug and I point it out. Half the time I'm bumbling around with what's still very new and beond my paygrade physics doodads to get my trains to "feel" right, not be scientifically accurate.

[cesarbl]

Could you post a screenshot with the "Force Information" on the F5 HUD shown? It would be helpful to determine which could be the origin of the problem.

[Jonatan]

cesarbl, on 11 April 2023 - 07:01 AM, said:

Could you post a screenshot with the "Force Information" on the F5 HUD shown? It would be helpful to determine which could be the origin of the problem.

Hot from the presses: Tim Muirs B&O 270, not modified. Speed increase began around 40-50mph.
https://cdn.discordapp.com/attachments/429042953755951124/1095367896068276345/Open_Rails_2023-04-11_05-20-00.png
https://cdn.discordapp.com/attachments/429042953755951124/1095367896437358693/Open_Rails_2023-04-11_05-20-03.png

With cutoff in reverse and closed regulator, speed decreases.
https://cdn.discordapp.com/attachments/429042953755951124/1095367897259458651/Open_Rails_2023-04-11_05-20-18.png

[cesarbl]

Thanks for the pictures. They discard a problem related to the adhesion part, so it must be something related to the Tractive Force calculation.

[steamer_ctn]

I agree that the locomotive should not accelerate, so I will have a look at it.

Unfortunately I am on holidays for three weeks so it will be when I return.

[Jonatan]

Was this looked into?

[steamer_ctn]

Jonatan, on 29 May 2023 - 05:47 AM, said:

Was this looked into?

Yes and no.

I had a look at it, and I think I understand the issue, but I have been working with Cesar in regards to the overall adhesion, and once that is finished then I will be reviewing some of the steamer code.