[beresford]

I haven't tried OR for a long time, but I uploaded X1.3.1-71-gad883ddd and tried a couple of scenarios from Severn Valley.

First I tried one with a 'Growler' hauling a train from Kiddy and at full throttle the train barely moved. I remember this is a function of the old diesel models for MSTS.

Then I tried Santa Special Northbound: Part 1, where an 8F hauls an 8 car train out of Kiddy. Here once the regulator was cracked more than 2% the train immediately accelerated to about 70mph with a final speed of 700mph or so forecast. Is there a significant change I need to know of?

[dennisat]

beresford, on 17 July 2019 - 09:36 AM, said:

First I tried one with a 'Growler' hauling a train from Kiddy and at full throttle the train barely moved.

I've had a look at this and it's the usual mash up of vacuum and air brake parameters that OR can't deal with. The solution, for the SVR activities, is to rewrite the braking parameters exclusively for vacuum brakes. It will then still work in MSTS.

beresford, on 17 July 2019 - 09:36 AM, said:

Then I tried Santa Special Northbound: Part 1, where an 8F hauls an 8 car train out of Kiddy. Here once the regulator was cracked more than 2% the train immediately accelerated to about 70mph with a final speed of 700mph or so forecast. Is there a significant change I need to know of?

This is absolutely weird. For some reason OR seems to have taken exception to this one loco and where parameters have to be assumed, it's assumed values really wildly too high, enough to lift an A380 off the runway. I've been trying to work out why but I've had no success so far. Comparing the eng file with other similar locos, there are some oddly specified values which I think OR would just ignore. However, I tried re-specifying them with correct syntax but it still won't work. I'll have another look later but it may be something for a bug report.

Dennis

[copperpen]

For some reason I modified my eng file for 48773 way back in January 2014, as far as I can see, I only added 4 ORTS parameters to it back then, all to do with the boiler. I am unable to get jet fighter performance out of it.

Eng file attached. two more parameters added to define locomotive and boiler type.

Attached File(s)

•  BR8F_280_48773.zip (5.98K)
  Number of downloads: 327

[dennisat]

copperpen, on 18 July 2019 - 10:12 AM, said:

Eng file attached. two more parameters added to define locomotive and boiler type.

Hi,

If you leave the parameters to default, this is what OR gives you for BR8F_280_48773:

Warning: Steam engine type parameter not formally defined. Simple locomotive has been assumed
Warning: Grate Area not found in ENG file and has been set to 15334.71 m^2
Warning: Evaporation Area not found in ENG file and has been set to 766735.4 m^2
Warning: Boiler Volume not found in ENG file, or doesn't appear to be a valid figure, and has been set to 994346.4 Ft^3
Warning: Steam boiler type parameter not formally defined. Superheated locomotive has been assumed.
Warning: Superheat Area not found in ENG file, and has been set to 2063269 Ft^2

These are astronomical figures.

However, another loco from SVR (GWR28xx_280_2857) which is a similar loco and has a very similar eng file, comes up with reasonable figures:
 GWR28xx_280_2857.zip (5.78K)
Number of downloads: 341

Warning: Steam engine type parameter not formally defined. Simple locomotive has been assumed
Warning: Grate Area not found in ENG file and has been set to 10.90287 m^2
Warning: Evaporation Area not found in ENG file and has been set to 545.1434 m^2
Warning: Boiler Volume not found in ENG file, or doesn't appear to be a valid figure, and has been set to 706.9731 Ft^3
Warning: Steam boiler type parameter not formally defined. Superheated locomotive has been assumed.
Warning: Superheat Area not found in ENG file, and has been set to 1466.969 Ft^2

These two eng files look like they were written by the same person and only values have been changed between the two locos.

Dennis

[copperpen]

None of the assumed figures would give "jet fighter" performance, just a lot of steam to use. What does affect speed very much are the cylinder dimensions, make those very large to use all that steam and the engine would probably fly with no wings.

On a slightly different note, as the activity runs in winter/snow having a lot of steam at high pressure can easily cause wheelspin if cylinder dimensions are over sized and that would very soon give high estimated terminal speed.

[dennisat]

copperpen, on 19 July 2019 - 02:30 AM, said:

On a slightly different note, as the activity runs in winter/snow having a lot of steam at high pressure can easily cause wheelspin if cylinder dimensions are over sized and that would very soon give high estimated terminal speed.

Hi,

V1...
Rotate!
V2....



Dennis

[slipperman]

Hi Chaps,
The problem with the Severn Valley 48773 is that the 'CylinderDiameter ( 18.5 )' line is missing its units; if it's changed to 'CylinderDiameter ( 18.5in )', the loco runs more normally :)
She does seem to be a little sluggish, but I'll leave it to others to tweak the parameter values and, hopefully, advise us accordingly!

There are a few other parsing errors concerning 'm/s' and 'n/m' in various vehicles, which aren't detrimental to the running of the consist.

Cheers,
Ged

[dennisat]

slipperman, on 19 July 2019 - 10:12 AM, said:

The problem with the Severn Valley 48773 is that the 'CylinderDiameter ( 18.5 )' line is missing its units; if it's changed to 'CylinderDiameter ( 18.5in )', the loco runs more normally :)

Well spotted Ged. I thought I'd tried all those combinations. OR must be assuming something other than inches if no unit is specified.

Dennis

[tary5]

Hi All
Would anyone care to try these Engine and Wagon files for an 8F, one for OR and one for MSTS. The sound and cabview lines may need editing to your choice.
Cheers
Terry W

 8F Engine and Wagon Files.zip (14.35K)
Number of downloads: 320

[darwins]

Hi Terry
I have had a look through the OpenRails files and have made a few suggested changes. I have attached a copy of my modifications.
These are my thoughts and changes:
Centre ( 0m 0m 0m ) deleted - not currently used in OpenRails
InertiaTensor ( Box(2.63m 3.91m 11.6m )) deleted - not reaquired in OpenRails

Mass ( 72.1t ) changed to Mass ( 72.1t-uk ) This is mass in Imperial tons rather than Metric tonnes.

Coupling (
Type ( chain )
Spring (
Stiffness ( 1e6N/m 5e6N/m )
Damping ( 6e9N/m/s 6e9N/m/s )
Break ( 7e9N 7e9N )
r0 ( 10cm 20cm ))

changed to

Coupling (
Type ( Chain )
Spring (
Stiffness ( 1e6 2e6 )
Damping ( 1e6 1e6 )
Break ( 1220kN 1220kN )
r0 ( 0cm 10cm )
)

Units removed from Stiffness and Damping as these seem to give error messages in OR. This might change as couplings are developed.

Break set as 1220kN being the UiC specification for the strength of a chain coupling and drawhook. Not sure if this should be the same for both numbers or not.

r0 you can adjust as you wish. For passenger trains, especially corridor trains I generally set close to zero to keep vehicles buffer to buffer. ( -5cm 0cm ) is good for corridor coaches.
for loose coupled, unbraked, freight wagons ( 10cm 20cm ) or ( 0cm 20cm ) seems good.

You might want to change:
ORTSNumberBrakeCylinders ( 1 )
ORTSBrakeCylinderSize ( 14in )
ORTSAuxilaryResCapacity ( 3.312ft^3 )

For something larger like:
ORTSNumberBrakeCylinders ( 2 )
ORTSBrakeCylinderSize ( 21in )
ORTSAuxilaryResCapacity ( 4.41ft^3 )

In reality an 8F would not have a vacuum brake cylinder or reservoir as it has steam brakes. However OR requires these, and if they are too small it seems to impact on the function of the train brakes (or at least it did in earlier versions - I can't remember if this problem has since been fixed).

I would be tempted to represent the steam brake operation like this for the loco:

MaxReleaseRate ( 10inHg/s ) Comment (* Steam brake - releases faster than vacuum *)
MaxApplicationRate ( 1.3inHg/s ) Comment (* Steam brake - delay for pressure to build up in brake cylinder *)

and for the tender:

MaxReleaseRate ( 10.0inHg/s ) Comment (* Steam brake - reacts faster than vacuum *)
MaxApplicationRate ( 1.0inHg/s ) Comment (* Steam brake - delay for pressure to build up in brake cylinder *)

Under special effects I have added: Cylinders2FX you might also want to add Injectors1FX and Injectors2FX either side under the cab near the back of the frames.

For the boiler I have changed:

BoilerVolume ( 320.0*(ft^3)" ) Comment (CTN Calculation)
ORTSEvaporationArea ( 2205ft^2 ) Comment (CTN Calculation)
ORTSSuperheatArea ( 551ft^2 ) Comment (CTN Calculation. Not required for saturated locomotives)

ORTSGrateArea ( 37ft^2 ) Comment ( CTN Calculation )

to use the dimensions for the LMS 3C boiler for 8012 onwards:

BoilerVolume ( 325ft^3 ) Comment ( calculated from boiler dimensions )
ORTSEvaporationArea ( 1650ft^2 ) Comment ( tubes 1479 + firebox 171 )
ORTSSuperheatArea ( 241ft^2 ) Comment ( LMS original 215, later 245, 230, 241 )

ORTSGrateArea ( 27.75ft^2 ) Comment ( CTN Calculation )

I am not sure why the CTN calculator gives such large over estimates for superheater area and grate area. It is probably based on US practice where they had larger grates to work longer distances often with poor quality fuel.

I have a lot of information about LMS and MR boilers but would like to collect more information about other British boilers to share as needed.

You have included a list of "Advanced Parameters". Without doing some research and testing I have no idea if any of these would be needed for the 8F.
Certainly they will not make much difference to pottering up and down the SVR. It might be a different matter for main line working.

For the brake system I have put in the standard LMS / MR ejector.
This was quite a weak ejector - a lot less powerful than the CTN default (or the GWR ejector!) so takes a bit longer to release brakes.

I am not sure why the controls for an 8F were set up with notches like lever reverse. I have replaced this with

Cutoff ( -0.75 0.75 0.01 0
NumNotches( 0 ))

which seems to better represent a screw reverse.

You might also want to delete Headlights( 0 1 0 ) as the driver can not turn oil lamps on and off from inside the cab.

Also deleted EngineVariables( ) as these are not used by OpenRails.

Finally added some resistance and load information to the tender.

Regards
Darwin

Attached File(s)

•  OR 8F.zip (7.57K)
  Number of downloads: 321