Coals to Newcastle

Open Rails Testing Page

Test Page Version History

25/01/2014 - Corrected documentation - "BoilerEvaporationRate" misspelling.

25/01/2014 - Added example of superheated locomotive for testing purposes.

Index

OR Steam Model Description

As suggested above, the steam locomotive is very complex. The current OR Steam model uses some of the same design factors and formulas, used by the original designers, to produce a generic representation of the steam locomotive. The performance of individual locomotives could be impacted by many different factors, such as:

• movement of the valve gear, i.e. when steam was admitted and exhausted from the cylinder
• size of steam pipes and openings
• amount of draught created for the fire

The current steam model developed for OR attempts to develop a common working model, for a simple saturated, and superheated locomotive, that is a representation for the way that a steam locomotive would perform. The accuracy of this representation may vary from locomotive to locomotive. To fully understand the actual performance of a locomotive a detailed test report would be required for the locomotive in question. This page uses some available test reports to compare the models performance against real life.

Test procedures

Reference should be made of the respective summarised test extract document found in the root folder of the relevant locomotive.

It is suggested that the 'debug' HUD be used to give maximum visibility of locomotive performance values. This can be acessed by pressing the "Shft-F5" keys a number of times.

Typically most of the tests were run at full throttle, so release the brakes, start the locomotive, and set the reverser to the desired level of cut-off, and when the locomotive reaches the dseired speed (rpm), hit the "Esc" key and compare the results. Bear in mind that the results may vary depending upon the model performance.

Key OR ENG file parameters

The following ENG file parameters are the key ones required to support the best performance of the OR Steam model. Some are new ones, especially created for OR and some are already used within the ENG file, but may require validation. They have been grouped in the ENG files for the above locomotives to make them easily recognisable.

Wagon Section of ENG File

The following parameters are used in the wagon section of the ENG file, or alternatively in the WAG file:

Comment ( ********* Start OR Steam Module Parameters - Wagon Section ********* )

Comment ( Speed: 100km/h, Weight - 4.704 tons (US), Drv Weight - 2.191 tons (US), Drag - 1, Area - 2.5m2, Bearings - Friction, Axles - 2 (1 Drv, 1 aux), Type - Steam Locomotive Standard )
ORTSDavis_A ( 502.8 )
ORTSDavis_B ( 1.5465 )
ORTSDavis_C ( 1.437525 )
ORTSBearingType ( Roller ) Comment ( If friction bearing, then leave out) )
ORTSUnbalancedSuperElevation ( 3in )
ORTSTrackGauge( 4ft 8.5in)
ORTSRigidWheelBase ( 3.37m )

Comment ( ********* Finish OR Steam Module Parameters ********* )

Engine Section of ENG File

The following parameters are used in the engine section of the ENG file, or alternatively in the WAG file:

Comment ( ********* Start OR Steam Module Parameters - Engine Section ********* )

ORTSDriveWheelWeight ( 2.12t )
ORTSEvaporationArea ( "2471*(ft^2)" )
ORTSFuelCalorific ( 15143btu/lb )
ORTSGrateArea ( "55.5*(ft^2)" )
ORTSSteamFiremanMaxPossibleFiringRate( 3000lb/h )
ORTSBoilerEvaporationRate ( 12.0 ) Comment (leave this out if not known, typically will be between 12 - 15)
ORTSDriveWheelWeight ( 2.12t ) Comment (If not a steam locomotive, then leave out)

NumWheels (2)
WheelRadius ( 40.0in )
BoilerVolume ( "448.5*(ft^3)" )
NumCylinders ( 2 )
CylinderStroke ( 26in )
CylinderDiameter ( 20.5in )
MaxBoilerPressure ( 205psi )
MaxTenderCoalMass ( 60000lb )
MaxTenderWaterMass ( 100000lb )

Comment ( ********* End OR Steam Module Parameters ********* )

Reference Documents

For those who wish to explore the operation of a steam locomotive in more depth the following documents may be of interest:

General