[hroch]

Hello,

In OR occurs permanent drop in tractive force, when it should not reduce.
https://youtu.be/bT7j5fUjORI

Locomotive in video download here:https://skura.msts.cz/109e/cd_380.zip
cabview:http://msts.web2001.cz/download/cab380.zip
sound:http://modely-msts.cz/zvuky/snd38X.exe

 TRAINSET.ZIP (11.54K)
Number of downloads: 298
My eng with real traction charakteristic and cvf for this locomotive. Traction characteristic is from this website. Traction force should not reduce at a speed range of 0 to 100kmh, if the throttle does not change.

Same issue without traction characteristics.
https://youtu.be/7Ze7siYfevw
in time 12:02:24 change advanced model adhesion. Same issue as simple model adhesion.
in time 12:02:55 decrease in tractive force from 81.3kN to 81.2kN
in time 12:03:08 added power, tractive force 162.5kN
in time 12:03:14 decrease in tractive force from 162.5kN 162.4kN
in time 12:03:39 decrease in tractive force from 162.4kN 162.3kN
in time 12:04:05 decrease in tractive force from 162.3kN 162.2kN

Please repair
Thanks.

 OpenRailsLog.txt (17.13K)
Number of downloads: 240

[Coolhand101]

 hroch, on 18 December 2017 - 05:58 AM, said:

Hello,

In OR occurs permanent drop in tractive force, when it should not reduce.
https://youtu.be/bT7j5fUjORI

Locomotive in video download here:https://skura.msts.cz/109e/cd_380.zip
cabview:http://msts.web2001.cz/download/cab380.zip
sound:http://modely-msts.cz/zvuky/snd38X.exe

TRAINSET.ZIP
My eng with real traction charakteristic and cvf for this locomotive. Traction characteristic is from this website. Traction force should not reduce at a speed range of 0 to 100kmh, if the throttle does not change.

Same issue without traction characteristics.
https://youtu.be/7Ze7siYfevw
in time 12:02:24 change advanced model adhesion. Same issue as simple model adhesion.
in time 12:02:55 decrease in tractive force from 81.3kN to 81.2kN
in time 12:03:08 added power, tractive force 162.5kN
in time 12:03:14 decrease in tractive force from 162.5kN 162.4kN
in time 12:03:39 decrease in tractive force from 162.4kN 162.3kN
in time 12:04:05 decrease in tractive force from 162.3kN 162.2kN

Please repair
Thanks.

OpenRailsLog.txt

I haven't used my electric locos in a while, but i thought this was recently hard coded in the sim to do with heat over time reduces the TE ?

If not, try giving the Max Force and Max Continuous Force the same value, ie 274kN!

Thanks

[hroch]

Coolhand101:
Even if the forces are the same I have the same problem. I have a force of 130.3 kN in the first video. The max continuous force in enf file is 230kN. In the second video is DASH, which has a force of 81.2 kN and then 162.5 kN. The max continuous force in eng file is 550kN. The warming of traction motors should not interfere in both cases. If it causes it.

[Coolhand101]

 hroch, on 19 December 2017 - 04:29 AM, said:

Coolhand101:
Even if the forces are the same I have the same problem. I have a force of 130.3 kN in the first video. The max continuous force in enf file is 230kN. In the second video is DASH, which has a force of 81.2 kN and then 162.5 kN. The max continuous force in eng file is 550kN. The warming of traction motors should not interfere in both cases. If it causes it.

I just done a quick test with my class 86 electric loco :


MaxPower ( 4040hp )
MaxForce ( 206.8kN )
MaxContinuousForce ( 206.8kN )

With advance adhesion on and ORTS Traction Characteristics set with continuous tractive effect at 39.5 mph. My axle drive force output was glued at 206.8kN until 39.5 mph.

Test 2

As above but with 25% power, running at 7 minutes, the axle drive force output was glued at 50.9kN until 39.5 mph.


The only time i see what you are experiencing is when i set MaxContinuousForce lower than max force and use the parameter ORTSContinuousForceTimeFactor ( 3600 ).

Thanks

[hroch]

Pardon Coolhand101. I was wrong. I entered a wrong max continuous force. You are right that, when the maximum force is the same as the max continuous force there is no drop in the traction force, when the force should not reduce.

But this is not a solution, because most electric and diesel-electric locomotives in the OR have a different maximum force and max continuous in eng file. There is a loss of tractive force on these locomotives and thus loss of power. From my point of view this is a bug and should be corrected. For example, Dash loses about 400N of tractive force per minute.

[copperpen]

The drop in tractive effort with the rise in speed when running at a fixed throttle setting is correct, not a bug. As speed increases, so does resistance until eventually a balanced speed is reached where tractive effort and resistance cancel each other out. The more streamlined a train is, the higher is the balancing speed for a given power setting. This train resistance is modelled using the Davis coefficients. With electric traction there is the added factor of heat generated by the traction motors which if allowed to rise too far will result in a loss of power which is why these do not run at high power settings for a long time period. A modern multiple unit with motors on many axles will be able to run at higher power settings for longer because the power/weight ratio per motor is much lower than with a locomotive hauled train.

I do however tend to take manufacturers figures with a healthy pinch of scepticism. They are produced as a means to sell the locomotive.

[hroch]

 copperpen, on 20 December 2017 - 03:23 AM, said:

The drop in tractive effort with the rise in speed when running at a fixed throttle setting is correct, not a bug.

Really?
http://109-e.wgz.cz/...-tech-parametry
Look down on traction characteristics. Trvalý výkon=Continuous power. The force is constant until 102kmh.
You do not know what is a three-phase asynchronous locomotive, because you are frozen at resistor, autotransformer locomotives with DC serial motors.
You did not watch my videos. On the second video is DASH, whose speed is 0kmh. The tractive force does not exceed the maximum continuous force specified in the eng file. Yet the traction force decreases. So explain to me why?

[Coolhand101]

Tractive effort reduces with speed but from a certain speed. Depending on the traction, this could be 10-15 mph on diesels, 25mph on EMUs, and 40mph on electric locos. The class 87 loco had a special mode which thyristor control was used, where the tractive effort was constant to 80mph instead of 40 mph.

Thanks

[copperpen]

Therefore I do not see this as a bug, just something that has not yet been coded so workarounds have to be made to get the data required. Maybe Serana could take a look at this, if he is still around.

As for being frozen at ancient DC type traction, not true. There have been AC traction locomotives around for a long time. Even your constant force to 102KMH has to give way to the laws of physics at that point, so I will say again, it is not a bug, just a fact that Open Rails physics does not cater for it right now.

[hroch]

Create an consist with Dash + 38US2GrainCar or use the default consist dlesson1.con. Release brake in locomotive using BailOffButton. Direction foward. Throttle set the second notch. Take a screenshot. Wait 15minutes and take a screenshot again. You see what I mean?

Tractive force is 162,6kN in zero speed. Time 12:00:58


After 15 minutes missing about 2.9kN in zero speed. Time 12:16:02. Tractive force is 159.7kN

What laws of physics do the locomotive give up?

 copperpen, on 20 December 2017 - 08:43 AM, said:

Even your constant force to 102KMH has to give way to the laws of physics at that point

Do You know what is a traction hyperbola and how the power is calculated on the tread of the wheels?
P=force(kN)*speed(kmh)/3.6 (implemented in OR too)
for locomotive cd380
in 102kmh speed P=(102*225)/3.6=6375kW
in 110kmh speed P=(110*205.3)/3.6=6273kW
in 120kmh speed P=(120*188.2)/3.6=6273kW
etc.
What laws of physics have the locomotive surrendered?