[steamer_ctn]

Jean-Paul, on 23 January 2023 - 12:11 PM, said:

Here are the files :

Thanks for that.

Jean-Paul, on 22 January 2023 - 10:38 AM, said:

tractive effort is perpetually oscillating,

I am a little bit confused as both of your screen shots show the Power In/Out rather then tractive effort.

Tractive effort (force) is found on the Forces Information HuD.

I have run a test with my test model at 100% throttle and 40% cutoff, with as set Drive wheel weight and also with weight increased to 2 x the actual. Both runs seem to show a similar tractive effort.

Also looking at the maximum and minimum values of "Axle Drive Force" at various speeds, which represents the input tractive effort of the locomotive, this appears to be within the same sort of bounds as shown in the graphs on the stock page displayed near the locomotive. So I can't see where TE is oscillating outside of the expected bounds.

So at the moment I can't see any issues with the TE calculations. I can't comment on the Power calculations apart from saying that I am unaware of any issues with them at the moment.

If I get time I will look at your ENG/WAG files and the power calculations when I get some time, however I will be away for a few weeks within the next few days, so it may not be for a while.

If you wish you can repeat my tests with my test model, and if you identify any issues using it I might be able to have a quick look at it.

[Jean-Paul]

steamer_ctn, on 23 January 2023 - 09:00 PM, said:

Thanks for that.


I am a little bit confused as both of your screen shots show the Power In/Out rather then tractive effort.

Tractive effort (force) is found on the Forces Information HuD.

I have run a test with my test model at 100% throttle and 40% cutoff, with as set Drive wheel weight and also with weight increased to 2 x the actual. Both runs seem to show a similar tractive effort.

Also looking at the maximum and minimum values of "Axle Drive Force" at various speeds, which represents the input tractive effort of the locomotive, this appears to be within the same sort of bounds as shown in the graphs on the stock page displayed near the locomotive. So I can't see where TE is oscillating outside of the expected bounds.

So at the moment I can't see any issues with the TE calculations. I can't comment on the Power calculations apart from saying that I am unaware of any issues with them at the moment.

If I get time I will look at your ENG/WAG files and the power calculations when I get some time, however I will be away for a few weeks within the next few days, so it may not be for a while.

If you wish you can repeat my tests with my test model, and if you identify any issues using it I might be able to have a quick look at it.

Hi !
Of course, I use extended HUD to do my tests... And I can't show, without a video, how TE varies, but if we are logical, if Power oscillates, TE = PE/speed oscillates also.
Then, no solution... Your test model works as good as possible, and mine no, because they are wrong, probably.
Anyone else could perhaps do the same test, and tell us if he sees the same problem ?
Cheers,
Jean-Paul

[Jean-Paul]

Hi !
Well, I did the test, with your model and consist.
No particular comments about your .eng file, except that's a more simple one than mines. You don't use improvements like "ORTSCylinderBackPressure" or "ORTSCylinderInitialPressureDrop", but I don't think it modifies the test.
My comments are as following :
- At low speed and wide opening of CutOff (up to 60 %), weak oscillations of TE, no wheelslip tendance (but adhesion is set to very high values for a large wheel locomotive - 30 % @ start, 19 % @ 50 mph)
- When speed increases, by lowering CutOff to respect abilities of boiler, relative oscillations become more and more consequent (in relative terms).
- Like the screenshot illustrates it, @ 55 mph, Tractive Effort varies from 15 to 51 % of its maximal value, i.e. a 240 % dispersion (=(51-15)/15).
- Number of substeps, which is 1 in the same conditions with 1.5.1-174 (without your modification) remains blocked at 50, for the whole duration of test. That means processor calculates continuously. Having a "big" computer, that's not a problem for me, but I wonder what could be the result with a weak PC configuration, on a "very busy" scenery.
- At 55 mph, rotation speed of wheels is around 233 rpm. Knowing that oscillations increase with rotation speed, it would be interesting to test for speeds > or = 300 rpm, frequently reached with high-speed engines.

No more comment to do.
I join an explicite screenshot.
Cheers,
Jean-Paul

Attached thumbnail(s)

• 

[copperpen]

For me, this latest addition to the steam locomotive code is just about perfect, reflecting as it does the actual way in which a steam loco works. When running a test I am not interested in the force information but rather use the locomotive information page to see the overall performance figures. There we see two states of information. Performance shows the steady increase/decrease of HP and TE rather like the graph drawn on paper. The Player loco and slip monitor on the other hand show the constantly varying figures tyhat a steam loco actually produces. The Power In/Out graph at the bottom of the page is rather like a continuous cylinder diagram.

Turning to your eng file for the 141R, I have modified it to properly reflect the number of driving and carrying axles, 4 and 2 respectively. It very closely matches the theoretical max TE when starting. 45.1K actual against 45.8K theoretical. I feel that it may be slightly down on power. According to its wiki entry it should produce about 2890HP at 50 mph but so far I have only reached 2700 at that point. I feel that may well depend on controller settings

[Jean-Paul]

copperpen, on 25 January 2023 - 08:28 AM, said:

For me, this latest addition to the steam locomotive code is just about perfect, reflecting as it does the actual way in which a steam loco works. When running a test I am not interested in the force information but rather use the locomotive information page to see the overall performance figures. There we see two states of information. Performance shows the steady increase/decrease of HP and TE rather like the graph drawn on paper. The Player loco and slip monitor on the other hand show the constantly varying figures tyhat a steam loco actually produces. The Power In/Out graph at the bottom of the page is rather like a continuous cylinder diagram.

Turning to your eng file for the 141R, I have modified it to properly reflect the number of driving and carrying axles, 4 and 2 respectively. It very closely matches the theoretical max TE when starting. 45.1K actual against 45.8K theoretical. I feel that it may be slightly down on power. According to its wiki entry it should produce about 2890HP at 50 mph but so far I have only reached 2700 at that point. I feel that may well depend on controller settings

Hi !
Thank you very much for your test ! I am reassured if you consider these variations as compatible with our simulator. To be honest, although considering the approach as very valid, I was afraid that the intensity of the cyclical variations would undermine the normal functioning of the simulation. Being used to extended HUD, I have a direct reading on both efforts (axle and drawbar). I'm not so attached to extended HUD, but it remains very useful for parametering... And with new version, drawbar effort remains stable, so, it works !
About a slight weakness in drawbar power, I think that, effectively, discrete values for Cutoff are responsible. It's a "facility" when I give my instructions with my .eng files : it's easier to explain to "apprentice drivers" to "reduce a notch" of Cutoff than to suggest to search the exact value matching with boiler production...! Or, perhaps, that's a problem of quality of coal !! :rolleyes:
Once again, thank you very much for your help, and congratulations on this development !
Cheers,
Jean-Paul