Monthly Archives: January 2015

happy new year! and updates

Happy new year! This year, 2015, the CK Holliday is 60 years old! (Or 61, if you consider her birthday in 1954 instead). It would be great if the simulator can be released this year in conjunction with her big birthday, wouldn’t it?

I’ll try my best, but there’s a lot of work to do yet. Unfortunately, I don’t have anything to “show”, but I can tell you about some of its progress:

  1. The engine can move! The throttle and reverser bar have been “installed” so with a sufficient steam pressure, the throttle can be opened to supply power to the cylinders.
  2. The throttle and reverser bar interact in a realistic manner. You can control the engine/train’s speed by either adjusting the throttle, the reverser, or both. Which one is better, or more efficient in term of steam usage vs motive power? You’ll have to experiment to find out
  3. I ended up having to add some custom scripts for better control of the throttle and reverser bar. For example, scrolling “down” on the reverser, if it was forward, will bring it back “up” to center (neutral). This is to prevent you from moving it passed center by accident. To move the bar passed center to backward you’ll have to hold down the left “alt” key while scrolling. Also, you can bring the bar up to center immediately anytime by clicking it with the middle mouse button. I hope this kind of control will be useful for you.
  4. The engine’s total “motive power” is modeled on the driver crank’s positions! (This is not the “tractive power” which doesn’t depend on the crank’s position). When the cranks are fully “up” or “down”, the cylinders are able to deliver maximum power to the drivers because the moment arm is the greatest. Whereas when the cranks are fully “forward” or “rearward”, minimum power is available because there’s no moment arm. Of course, for this reason the left and right side cranks are offset.
  5. This means that the power delivered to the drivers continually changes! While the engine is moving, there’s a small variation in power delivered as the drivers turn. When the speed is fast enough, it all averages out, so this effect is most pronounced when the engine is slow.
  6. When the engine is stationary there’s a certain crank alignment (or really the valve alignment) where the engine can’t deliver any power so it just won’t start! This is called dead center and it is modeled. To remedy this situation, you’ll have to shift the valves by moving the engine backward a little bit to get of alignment, then you’ll be able to get moving forward again.
  7. Below is an example of this situation. The engine only moved a few inches forward before the valves got caught in dead center—there wasn’t enough momentum yet to move the engine through the dead zone. The engineer then moves the engine rearward a foot or so, then the engine was able to move forward through the dead zone. You can watch the linking shaft closely to see the engineer moving the reverser bar.

There’s plenty more of work to do, including wheel slippage that you can see above. Right now I place it about 40-45% done.

The simulator will come with a comprehensive documentation to help you learn and understand the engine as well. More on this later.

Happy new year!


Filed under Steam Engine Simulator