Category Archives: Steam Engine Simulator

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!

To make a steam engine from scratch, like baking an apple pie, first you must first invent the universe.

So in addition to writing my own physics for the steam engine, I’ve also created a model of the world, because presumably you’ll want to see the world outside from the cab windows.

As it turns out, it’s quite a bit like building a table top model railroad! Place the tracks, plant some trees, shape the hills.

The track is about 2.5 miles long—quite a bit longer than the Disneyland tracks. This gives me plenty of room to stretch the Holliday’s legs and run tests.

I plan on including this test track with the simulator, so you can have some variety and try running her in a different environment (like experiencing left turns!)

Keep in mind that the sim’s focus is inside the cab and the engine. The world view is only meant to give you a basic idea of how the engine is traveling, so it won’t be elaborate set pieces nor external views of the train. For that, there are other train “sims” that fulfill that role.

Here’s video preview #1 of the upcoming Disneyland Railroad CK Holliday steam locomotive simulator. Keep in mind that this is an alpha version: a lot of features are preliminary and are not yet completed. But, this video should give you a taste of what the simulator is capable of, and give you an idea of its details.

Happy Friday!

I forgot to tell you something from the earlier previews: the pictures I posted earlier are not static pictures! Here’s what it looks like in motion. Enjoy!

I don’t suppose that everyone would appreciate the natural wood cab (which is of course the wrong color!). So, just to please the die hard fans out there, here she is with her DRR prototype green:

Note that not only the cab color itself was changed, but the reflections and the tone of everything else in the cab also changed slightly green. This is because of the color bleeding from light bouncing around within the cab.

But, maybe I changed your mind and now you like the natural wood cab? Well… maybe you can choose yourself which one you’d prefer…

…oh, look at that! It seems that there are other options that you can change, too.

Checkout the water level in the sightglass!

In “Disneyland Railroad speak”, “two nuts” is the correct level of water to maintain. Of course, on the real train, the water level fluctuates with the amount of heat being applied (converting to steam), the amount of water being injected into the boiler, and even the movement of the train!

A skilled fireman must be able to keep a steady level of water despite all the forces above.

I’m still alive! Let’s keep this blog going… recently I made a digital painting (mockup) of the CK Holliday cab. Of course, it’s based on the drawing in the plan book (page B50 if you have it and want to follow along).

For one thing though, I really like the look of the Holliday cab with a natural ash wood look, rather than the bright green in the interior. It looks like it belongs in the 1850’s, and the combination of black, bright brass, and natural wood is just so elegant and… well… manly!

Here’s a closeup of the gauge. 0psi… nothing exciting.

Do you like the cab with or without the pipe wraps?