[darwins]

I have just tried an experiment to measure resistance using a train made up of three 2-BIL electric multiple units in various formations.

The resistance values for the motor cars being

	ORTSDavis_A ( 551 )
	ORTSDavis_B ( 16.4 )
	ORTSDavis_C ( 5.70 )

	ORTSWagonFrontalArea ( 91ft^2 )
	ORTSDavisDragConstant ( 0.0028 )
	ORTSTrailLocomotiveResistanceFactor ( 0.223 )

and those for the driving trailer cars

	ORTSDavis_A ( 460 )
	ORTSDavis_B ( 11.4 )
	ORTSDavis_C ( 5.70 )

	ORTSWagonFrontalArea ( 91ft^2 )
	ORTSDavisDragConstant ( 0.0028 )
	ORTSTrailLocomotiveResistanceFactor ( 0.223 )

These are the observed results from screenshots taken at 30 mph
https://i.imgur.com/PEJFSGC.jpg

https://i.imgur.com/09ynHoM.jpg

https://i.imgur.com/pj6hSH0.jpg

https://i.imgur.com/VqJiS2N.jpg

The total resistance in each case being
https://i.imgur.com/1R9YSX6.jpg

As far as I can tell the order in which motor and trailer cars are arranged makes no difference to the total resistance of the train.

[Coolhand101]

Hi Darwin

Now swap one of the intermediate trailers from ENG to WAG and see the difference in wind resistance.( same weight and dimensions).

If the Bils physics are set up correctly, they will balance at 41mph on a 1in100, 52mph on 1in200 and 58mph on the level. They achieved 64 mph on the higher voltage on a charter run between farnborough and hook.

I never use the max velocity parameter in the engine file as the EMUs had no speed limiter.

Thanks

[James Ross]

 steamer_ctn, on 12 September 2021 - 02:16 PM, said:

IMHO I feel that we should strive to only use "realistic" parameter values.

100% with you on this!

I am also happy to include validation code for spotting weird/out-of-bounds values when developing content (opt-in)

[darwins]

I did just try changing the DTC from eng to wag.

The result was identical to when it was an eng.

I have attached my eng (and wag files) - all tests were in U2021.09.07-0721

For advanced configurations - using traction curves, then MaxVelocity ( ) should not limit the actual speed, but simply show on the track monitor if you are exceeding the "permitted" speed.
I am very torn about including MaxVelocity in any file, until the late 1930s there were few if any absolute speed limits for rolling stock in UK. (Also few trains had speedometers anyway.)
Ideally it would be a wag file function instead of or as well as an eng file function. So that if a vehicle in the train was limited to 60mph or 30mph or whatever then that would be shown in the track monitor.

Attached File(s)

•  2BIL_SR_DTC_12071.eng (15.45K)
  Number of downloads: 259
•  2BIL_SR_DTC_12071.wag (15.45K)
  Number of downloads: 249
•  2BIL_SR_MBSL_10614.eng (31.96K)
  Number of downloads: 241

[Coolhand101]

I won't have access to my computer until Tuesday, so I'm viewing this on my phone, but it appears the wag file you posted is an engine file, as certain parameters do not work for WAG files. If not, I'm very interested to try this on my own 2-Bils.

When testing the wind resistance on my EMUs, I would always had identical ENG and WAG cars in the same consist and got almost twice the wind resistance from the ENG cars than the WAG cars for the same weight and dimensions. I was hoping control trailer/cab cars would see these as WAG coaches under wind resistance.

Also, I always thought the max velocity showing on track monitor was via the consist velocity file?

Thanks

[Laci1959]

 James Ross, on 16 September 2021 - 10:36 AM, said:

100% with you on this!

I am also happy to include validation code for spotting weird/out-of-bounds values when developing content (opt-in)

  AirBrakesMainMaxAir Pressure ( 10bar )  
        AirBrakesMainResVolume ( 1200l )  
        AirBrakesCompressorRestart Pressure ( - 8.8bar )  
        AirBrakesMainMinResAir Pressure ( 7.6bar )   
        AirBrakeMaxMainResPipePressure ( 5 bar )   

steamer_ctn wrote in the above code that this is not correct because the negative sign means a vacuum. If it were a vacuum brake, they would not argue. But assuming a vacuum on a pressurized brake may not be a good idea. There, a value lower than normal atmospheric pressure is not possible. AirBrakesCompressorRestartPressure (-8.8bar) means that this air tank (OR uses the name Main Reservoir) is filled by the air compressor in the rear locomotive.
For a power-free controller, these settings should be retained. Another important condition is that the locomotives and control cars must have the BrakeSystemType ("Air_twin_pipe") or BrakeSystemType ("EP") setting in the Wagon section.
THIS HAS WORKED WELL NOW!
I asked the drivers who play the OR, there is a Main Reservoir on the control car. There are two wired systems. The charge air pipe is marked in yellow and is not connected to the brake air pipe in any way.

Sorry if you have difficulty understanding, google will translate.

Sincerely, Laci 1959

[Laci1959]

https://kephost.net/p/2021/37/6919_31df20691d8c.png
https://kephost.net/p/2021/37/1631_8d9aa0d9f1b7.png

Control wagons with " non - existent " main air tank ( Main Reservoir ).
Editing.
I apologize for the 1200l incorrect data, this is what my colleague just brought to my attention. The actual figure is 200 liters at the main air tank ( Main Reservoir ).

[mozdonyos]

I think the developers should be given the opportunity to be a user of each country, able to configure the vehicles of their own country.
In Hungary, on the control car, there is no compressor, you get the necessary air from the locomotive, the main air tank line.
On the other hand, there is a control car that has a heating engine and the assembly gets the heating from there, not from the locomotive.
I ask developers not only to think of a particular country (such as Britain or Russia), but also to be able to configure vehicles from other countries.

[darwins]

 mozdonyos, on 17 September 2021 - 09:59 AM, said:

I think the developers should be given the opportunity to be a user of each country, able to configure the vehicles of their own country.
In Hungary, on the control car, there is no compressor, you get the necessary air from the locomotive, the main air tank line.
On the other hand, there is a control car that has a heating engine and the assembly gets the heating from there, not from the locomotive.
I ask developers not only to think of a particular country (such as Britain or Russia), but also to be able to configure vehicles from other countries.

I think that is an excellent idea. Ideally the program should allow maximum flexibility in how users configure locomotives, carriages and wagons.

At the same time I can also understand that it is more difficult (and time consuming) to write code that will be flexible, rather than writing code that can only handle a narrow range of specified situations.

For the case of a pull and push train, propelled by a steam, diesel or electric locomotive then I doubt that there are any control trailers that have an idependent compressor or main reservoir. In such cases so long as the locomotive has a compressor and reservoir the brakes should work. [It does not really matter how the code handles this internally so long as the user sees similar operation for both pulling and pushing.]

For the case of diesel and electric multiple units there are it seems many variations

Driving Motor car with compressor and main reservoir / Trailer cars and control trailers without either

Non-driving Motor car with compressor and main reservoir / Trailer cars and control trailers without either

Non-driving Motor car without compressor and main reservoir / Trailer car with compressor and main reservoir / Control trailer without either

Non-driving Motor car and trailer car without compressor and main reservoir / Control trailer car with compressor and main reservoir

Driving Motor car with compressor and main reservoir / Trailer cars without either / Control trailer car with compressor and main reservoir

Driving Motor car with compressor and main reservoir / Trailer cars without either / Control trailer car main reservoir fed by separate dedicated pipe within unit

Driving Motor car with compressor and main reservoir / Trailer cars without either / Control trailer car main reservoir fed by main reservoir pipe that runs throughout the train

Driving Motor car with main reservoir, but no compressor - Reservoirs are recharged by compressors at terminal stations. (This was common in the early 20th century)

So it might be reasonable, that these can be shown as specified in the various eng or wag files above. The total reservoir capacity of the train being the sum total of all the reservoirs and the total reservoir charging capacity being the sum total of the charging capacity of all the compressors [Again I don't think it matters how the code calculates this internally so long as it appears correct to the train driver in the sim.]

[Coolhand101]

 darwins, on 16 September 2021 - 10:49 AM, said:

I did just try changing the DTC from eng to wag.

The result was identical to when it was an eng.

I have attached my eng (and wag files) - all tests were in U2021.09.07-0721

OK, I have now studied the WAG and ENG files of the BILs trailer cars and I can see the new parameter "type = control".

I cannot check this myself, but it appears the wind resistance hasn't changed for control trailers, being identical to 'Engine' trailers.

The only way you will see the difference is substituting an actual original WAG file for one of the DTC cars in your setup, ie:

ENG
CONT
ENG
WAG
ENG
CONT

Thanks