Steam Effects

Aim - this section provides an overview of the typical operation of special steam effects on the steam locomotive, and describes how to define these effects in Open Rails (OR) WAG and ENG files.

If you wish to provide any feedback on this page, please use the contact page. It would br great to have some feedback as this helps to ensure the accuracy of the information and models.

Index

Overview of Key Steam Effects on NSWGR Steam locomotives

Steam Effects Code - Structure and layout in Open Rails

Code Segments for Various Steam Effects Examples

Useful References


Overview of Key Steam Effects on NSWGR Steam locomotives

The ancillary devices on a steam locomotive, such as the air compressor and water injectors are typically powered by steam from the boiler. Steam for these devices is piped around the locomotive. Thus, a steam locomotive can have steam exhausting from it at various locations. Using a NSWGR P Class (C32) locomotive as an example the principal steam powered devices are shown in the diagram below, and their basic operation described.

The actual locations of the actual steam effects may vary slightly from locomotive to locomotive.

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Steam Effects Code - Structure and layout in Open Rails

Steam exhausts on a steam locomotive can be modelled in OR by defining appropriate steam effects in the SteamSpecialEffects section of the ENG file. Each effect has a name which must be included in the ENG file, and these names are shown in the following section.

OR supports the following special steam effects:

  • Stack (named StackFX) - represents the smoke stack emissions. This effect will appear all the time in different forms depending upon the firing and steaming conditions of the locomotive.
  • Steam cylinders (named CylindersFX and Cylinders2FX) - two effects are provided which will represent the steam exhausted when the steam cylinder cocks are opened. The effects are provided to represent the steam exhausted at the front and rear of each piston stroke. These effects will appear whenever the cylinder cocks are opened, and there is sufficient steam pressure at the cylinder to cause the steam to exhaust, ie, when the regulator is open (> 0%).
  • Air compressor (named CompressorFX) - represents a steam leak from the air compressor. Will only appear when the compressor is operating.
  • Turbo-generator (named GeneratorFX) - represents the emission from the turbo-generator of the locomotive. This effect operates continually. If a turbo-generator is not fitted to the locomotive it is recommended that this effect is left out of the effects section which will ensure that it is not displayed in OR.
  • Whistle (named WhistleFX) - represents the steam discharge from the whistle.
  • Safety valves (named SafetyValvesFX) - represents the discharge of the steam valves if the maximum boiler pressure is exceeded. It will appear whenever the safety valve operates.
  • Water injectors (named Injectors1FX and Injectors2FX) - represents the steam discharge from the steam overflow pipe of the injectors. They will appear whenever the respective injectors operate. Injector 1 is normally operated by the Fireman and is the main Injector in use.

NB: If a steam effect is not defined in the SteamSpecialEffects of the ENG file, then it will not be displayed in the simulation. If the effect is defined but all the direction parameters are set to zero the effect will not be displayed.

Note: It is good practice to put notes into the ENG and WAG files to act as reminder for any assumptions made, or define which steam efect is being referenced. These notes can be made with comment statements as shown below:

Comment ( Injector - Left )

Within each individual steam effect the following information is defined:

  • Effect name - name defining which effect is defined (see above text for a list of the names).
  • Effect location - location on the locomotive (given as an x, y, z offset in metres from the origin of the wagon shape).
  • Effect direction - direction of emission (given as a normal x, y and z).
  • Effect nozzle width - size of the exhaust nozzle in metres.

Location - Typically the origin point is in the centre of the locomotive, with the x, y and z axis describing a location referenced to this point. When looking to the front of the locomotive from the cab:

  • X axis - to the right (+ve), or left (-ve)
  • Y axis - in up (+ve) or down (-ve) direction.
  • Z axis - to the front (+ve) or back (-ve) of the origin.

Direction - The direction of the effect (vector) is defined with the x, y and z axes using the same convention as the location stated above.

In most cases the effect is only required to show in one direction along the x, y or z axes. This is simple to define as in the following manner,

  • X axis - to the right (+ve), or left (-ve)
  • Y axis - in up (+ve) or down (-ve) direction.
  • Z axis - to the front (+ve) or back (-ve) of the origin.

Any number greater or less than zero can be used for the single direction flow but it is obviously more convenient to use 1 or -1.

Angles can be created by visualising the diagram below, and allocating appropriate numbers to the y and z axes. A 45 deg. angle vector would have two of the axes with either a 1 or -1 value depending upon the direction required.

A shallower 20 deg. angle can be created as below.

The Y axis has been determined by using tan theta. Tan (20 deg) = 0.364, where Z is assumed the principle axis and designated a value of 1.

Y could have been chosen as the principle axis. In this case Y=1 and Z=tan(90-theta) = tan (70 deg) = 2.7474. This will produce exactly the same effect.

The third dimension X may also be introduced if required and calculated in a similar manner as above.

The typical structure of the steam effects section for a ENG files is as follows:

Effects (      
   SteamSpecialEffects (
                  

   Effect Name (
                           Effect location
                           Effect direction
                           Effect nozzle width
                     )
           )
       )

Note: It is important to ensure that the opening and closing brackets for the steam effects section match up, otherwise errors maybe generated.

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Code Segments for Various Steam Effects Examples

The steam effect examples on this page represents use of the steam configuration parameters described above to define different types of steam effects.

This type of code goes into the ENG file.

Typically the lines shown in red text are the only ones that would need to be changed to suit individual locomotives.

To locate an effect, use the "MSTS Positioning Tool" in Shape Viewer to correctly define the location of the steam effect. Just open the positioning tool as a second shape, move it to the position you want the new view/effect/light, and read the coordinates off the "Position Second Shape" window. Copy the values determined by Positioning Tool into the location and direction fields of the parameters in the ENG or WAG files, and start OR to test the effect. PosTool is available from TrainSim. For effects that take a bit of effort to activate in the the Sim, it maybe worthwhile to temporarily use an easier to activate effect to correctly position the effect. For example, the whistle effect can be used to find the correct position for most effects. Once the correct position is found the position information can be moved to the correct effect code block.

Steam cylinder cock

This is a example of how the steam cylinder cocks can be set up. Note that there are two different effects representing the two ends of the piston stroke. It is suggested that these are "reversed" on the opposite sides of the locomotive.


Comment ( Cylinder - Left/Rear )
    CylindersFX (
          -1.0485 1.0 2.8
          -1 0 0
          0.1
         )

Comment ( Cylinder - Left/Front )
    Cylinders2FX (
          -1.0485 1.0 3.7
          -1 0 0
          0.1
         )

Comment ( Cylinder - Right/Rear )
    CylindersFX (
          1.0485 1.0 2.8
          1 0 0
          0.1
         )

Comment ( Cylinder - Right/Front )
    Cylinders2FX (
          1.0485 1.0 3.7
          1 0 0
          0.1
         )
Air compressor

This is a example of how the air compressor(s) can be set up. Note that in this instance there are two compressors on the locomotive, so the same effect can be used twice at different locations to model this effect.


Comment ( Compressor - Back )
    CompressorFX (
          -1.15 2.65 -1.75
          -1 -1 0
          0.05
         )

Comment ( Compressor - Front )
    CompressorFX (
          -1.15 2.65 -1.15
          -1 -1 0
          0.05
         )

A working excample demonstrating the above concepts has been built using the Atlantic on the stock page. Give the locomotive a run to test the functionality and look at the SpecialSteamEffects section in the ENG file for a view of how to set up these effects.

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Useful References

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