Algodoo

The general shape is based roughly on a type of narrow gauge 0-6-0 manufactured by Anglo-Franco-Belge and Tubize around 1948.

Other parts were assembled wherever they seemed to fit, including the valve gear. It's set up in an inside-admission layout, but it’s not precisely built or tuned.

The locomotive features a "Kuhn slide" mechanism, like the one seen on the 60163 Tornado. In this setup, the "lifting arm" directly controls the "radius rod," skipping the "lifting link" that would normally create a different swinging motion.

This is also an arcadey steam locomotive simulator with made-up values and messy scripting, aimed to grasp some of the feelings I've experienced from various train games.

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Controls

[W/S] - throttle
[-/=] - adjust fuel input (-1/+1)
[Arrow Up] - add fire (hold)
[Arrow Down] - brakes (toggle)
[Arrow Left/Right] - reverser
[X] - release vehicle

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Guide

- To start, increase fuel input, then add fire. As the fire temperature rises, the circle will light up and the temperature needle move clock-wise, generating steam.
- To decrease fire, reduce fuel input to 0 briefly. Keep it at 0 in order to put it out.
- Fire rises easier when the engine is moving under its own power, as bursts of exhaust increase the draft that draws more air into the firebox.
- It has unlimited fuel and water, but the fuel input degrades when the fire is lit, the hotter the faster.
- Steam pressure drops as it enters the cylinders. Control the throttle and the reverser to keep the pressure needle above the upright position for better power.
- It is possible to take advantage of the simulation inaccuracy at speed and accelerate with the reverser within the neutral position, which gives slightly better efficiency at lower throttle.
- Top speed without any cars attached is maybe 50 km/h (~31 mph) before steam generation couldn't keep up anymore.

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Scene Notes

- Gauge faces and the number plate use a texture to overcome inaccuracy of object positioning beyond killer plane.
- Most of the scene's scripts are built into the fiery circle and the 2 pistons as their 'custom local variables' or in their postStep, and comunnicate remotely using 'global variables (scene.my.*)'.
- This global variable is used to generate absolute value: scene.my.abs = (n)=>{n < 0 ? - n : n}
- Lasers change the states of the piston-boxes' custom local variables for the attached springs to read and change their constant accordingly.
- RPM of the rear driving wheel is used to influence exhaust draft value which affects fire temperature.
- The analog-style speedometer also reads the RPM; its digital-style counterpart reads its own horizontal velocity instead.
- The scene runs at 100 Hz by default. It can run at 60 Hz as well, with reduced top speed and less effective couplers.
- It is possible to switch the speed unit: right-click on the digital-style speedometer, doing so selects a 5-object group. With the selection still active, navigate to their Script Menu, and look for a variable named _unit near the top left. Change its value between "kph" and "mph" with the "". Any other value would result in the texts on the meter turning into a question mark.

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Changelog

- Update piston springs' script structure; now similar to this scene: http://www.algodoo.com/algobox/details.php?id=244311
- Change steam level reading; 100% is now at the red dot of the steam gauge.
- Change safety valve behavior; it opens at 102% and closes at 95%.
- Add visual feedback when adding fire.
- Add 'leaky' steam chest simulation; pressure drops when throttle is closed (2024.12.27)

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