New: Steam traction modelling

[leezer3]

This is the start of implementing a new steam traction model.
Some basic ideas pulled from the BVEC_ATS / OS_ATS implementation, but this is intended to run solely within the main game.

Not yet implemented into the main simulation, doesn't build properly, untested at the minute....

Aimed for features:

• Exhaust and live steam injectors.
• Cutoff, including ineffective range.
• Fire size / area.
• Blowoff.
• Basic valve gear and stroke.
• Blowers.

TODO:

• Acceleration curves need hooking in somehow.
• More research into the numbers and assumptions.
• Actually test this.
• Animated variables to hook into all of this.
• Percentage based power / reverser handles.

New XML properties (WIP, names may change):

SteamEngine - The base node to setup the traction model

Boiler - Contains boiler related properties

• WaterLevel - Sets the initial water level in the boiler
• MaxWaterLevel - Sets the max water level in the boiler
• SteamPressure - Sets the starting steam pressure
• MaxSteamPressure - Sets the max steam pressure
• BlowoffPressure - Sets the pressure at which the blowoff triggers
• MinWorkingPressure - Sets the minimum working pressure
• SteamGenerationRate - The number of units of water converted into steam per second
• LiveSteamInjectionRate - The number of units of water injected per second by the live steam injector
• ExhaustSteamInjectionRate - The number of units of water injected per second by the exhaust steam injector

Firebox - Contains firebox related properties

• Area - The initial area of the fire
• MaxArea - The max area of the fire
• MaxTemp - The maximum temperature of the fire
• ConversionRate - The number of fuel units burnt per second, and converted into temperature units
• ShovelSize - The number of fuel units added per shovelful

CylinderChest - Contains cylinder chest related properties

• StandingPressureLoss - The standing pressure loss in units per second
• BasePressureUse - The base pressure used per wheel revolution (e.g. a single complete stroke)
• SniftingValve - None , Manual , Automatic and AutomaticRegulatorTriggered
• CylinderCockLeakRate - The number of pressure units leaked per second when open with full regulator

ValveGear - Contains valve gear related properties

• WheelCircumference The circumference of the driving wheel of the valve gear (used to define the base wheel position for cranks / pivots)

Crank - A crank position for use in animation, with the following properties:

• Radius The radius from wheel center of the crank
• Length The length of the attached crank rod
• Offset The number of degrees offset from zero at the start of the simulation

Pivot - A pivot position for use in animation, with the following properties:

• Radius The radius from wheel center of the pivot
• Offset The number of degrees offset from zero at the start of the simulation

Tender - Contains tender related properties

• CarIndex - Sets the index of the tender car if a separate car (n.b. this car may carry no other cargo)
• FuelLoad - The starting fuel load
• FuelCapacity - The starting fuel capacity
• WaterLoad - The starting water load
• WaterCapacity - The starting water capacity

[ginga81]

I want use Japanese Steam locomotive's Bypass-cock.
At the BVEC_ATS, our presentation wasn't still well.
This time, I want to requre.

[ginga81]

One more after.
Using something that calculates the rotation of the cylinder rod will not cause wheel slipping.
I would like it to move at high speed in conjunction with the speedometer that the driving wheels are spinning and the rods are also spinning.
I want to show the wheel slipping for My D51, so only used png.
StateFunction can change by slipping speedmeter's speed.

[ginga81]

In this book, written the Bypass Unit's explanation.
Please consider and I wish to the implementation this.

蒸気機関車メカニズム図鑑
細川武志 著
グランプリ出版
ISBN978-4-87687-317-3
Translation quoted from 142P
Translation by F81_tec200.

Steam Locomotive mechanism pictorial book
grand prix Publishing

[ginga81]

Additionally, Steam Chamber Air Valve unit also wish to implementation.
Please consider also this and I wish to the implementation this.
In Japanese steam locomotive, this unit's operating steam pressure is about 5 kg/cm2.
Under the 5 kg/cm2, open the valve.
When the open and close, the another each sound is generated.
When this valve is opening and steam pressure is high, the noisy sound generated one time, and steam pressure to 0 to suddenly.
But when the steam pressure is down in advance under the 5kg/ch2, the sound is not generated.
When the valve is opening and add the steam pressure from zero, the valve is close and sound generate one time.
But, not need the 5kg/cm2.

I don't know about the another countly's locomotive(I think that this is using only about Japan only.)
So I think perhaps that it will set the default value is 5 kg/cm2.
But I think that this value will need to valiable.

蒸気機関車メカニズム図鑑
細川武志 著
グランプリ出版
ISBN978-4-87687-317-3
Translation quoted from 134P
Translation by F81_tec200.

Steam Locomotive mechanism pictorial book
grand prix Publishing

[leezer3]

Will see what I can do, but bear in mind this is still going to be relatively simplistic simulation.

https://advanced-steam.org/5at/technical-terms/steam-loco-definitions/bypass-valves/

FWIW, bypass / snifting valves (UK term) were never especially common here, now that i know exactly what you're talking about from the diagram. Normal practice here would be to coast with a tiny bit of regulator, which also helps with overcoming the rolling resistance of the train & keeps things lubricated. (everything is lubricated via atomised oil in the steam)

They tended to be used more widely in countries who used steam traction much later, with the associated superheated, higher boiler pressures etc.

The second (air chamber valve) would appear to be a more automatic variant on the same basic idea. Probably what we'd call a drifting valve.

Not quite clear why both were required on the same loco, but shall see where things go.

[ginga81]

I already know that overseas, as you said, it is closer to mid and the regulation valve is slightly opened to make it run close to this.
I have drive some England's steam locomotives with Steam's Train Simulator 20xx.
(I like BR/LNER Class J50 that is feel very real.)
But, these are very important elements in more real simulating Japanese SL.
And I think it can be said that these are evolutions unique to Japan.
At my D51, I wanted to include these, but at 2014, my English vocablary wasn't good, so I couldn't say more for BVEC_ATS.
So, I was include to D51 was dummy by-pass cock by reverser lever.
In this time, his english and by this book, we can say these acculately.

At Japanese railway museum at Saitama Prefecture, change from order to lottery.
So, now we can't drive D51 simulator is incredibly impossible.
So, I want to more real simulate.

[JunmoreHeavyBox]

I don't think there's anything interesting about copying BVEC_ATS steam locomotive wheel linkage animation, but an interesting start.
Here are a few of my tips...
It seems to me that steam locomotives have two abstract wheel linkage objects indexed as 0 and 1, with angles that differ by 90 degrees. There is no such thing as a left or right linkage. Think of a three cylinder steam locomotive.
Consider an articulated steam locomotive such as the Big Boy, which requires two sets of wheel rod sets.

Idea Demonstration

<WheelLinkages>
    <WheelLinkage><!--WLIndex 0-->
        <Radius>0.75</Radius>
        <Height>0.8</Height><!--Piston centre from ground-->
        <Stroke>0.8</Stroke>
        <LinkageAngle>120</LinkageAngle><!--LkIndex 0-->
        <LinkageAngle>240</LinkageAngle><!--LkIndex 1-->
        <LinkageAngle>0</LinkageAngle><!--LkIndex 2-->
    </WheelLinkage>
    <WheelLinkage><!--WLIndex 1-->
        <!--Data...-->
        <LinkageAngle/ >
        <!--LkIndex 3, 4, 5-->
    </WheelLinkage>
</WheelLinkages>

The height difference between the piston and the wheel radius can change the acceleration characteristics and the timing of the sound trigger, whether the animation is used or not is irrelevant.

Ideally everything in the wheelbar set is synchronised, while multiple wheelbar sets like two bogies with Speedometer variables may have angular deviations after a certain number of miles.

According to the presentation, linkage indices 0, 1 and 2 belong to wheel linkage group index 0, linkage indices 3, 4 and 5 belong to wheel linkage group index 1, and so on. If you customise them, let's say in a wheel linkage group with two connecting rods, think about its index.
These variables can be used whenever Animated objects are used by the same vehicle.
WheelRotatei The wheel rotation animation, where i represents the index of the wheel rod group to which the wheel belongs.
WheelLinkageZi The animation of the wheel linkage moving along the Z axis.
WheelLinkageYi Animation of the wheel linkage moving along the Y-axis.
PistonLinkageRotatei Animation of the piston linkage rotating along the X-axis.
PistonLinkageZi Animation of the piston linkage moving along the Z-axis.
Where i represents the Linkage index.
Perhaps some complex steam locomotive linkage animations could be produced.

If possible, I would like to refine the customisation to a custom radius for each wheel, a custom stroke for each linkage and a custom piston height. However, I have abbreviated the presentation.

(= n =)

[JunmoreHeavyBox]

Mention of the custom wheel radius of each wheel brings to mind a geared steam locomotive with piston that rotate faster than the walking wheels. Regardless of the reduction ratio, it is synchronised in the wheel linkage set, as it is the gear-drive rod that transmits the power.
Similarly, universal telescopic rods can be attached to the wheels of a coal water tender to turn it into a power tender, but also this type of drive necessitates that the wheels of the power tender remain synchronised with the animation of the locomotive wheels in a wheel linkage set.
哔哩哔哩 【铁道】美国谢式（SHAY）直立汽缸蒸汽机车 充满机械美感的慢速走行 森林铁道爬坡专用蒸汽机车
哔哩哔哩 齿轮传动机车——V字排列双缸Heisler海斯勒式蒸汽机车
哔哩哔哩 倾斜汽缸 齿轮传动的 "climax"蒸汽机车 运行记录

Think of a rack and pinion steam locomotive, which might have two sets of wheel linkage sets. Unlike articulated steam locomotives, there is always a wheel rod set that drives the running gear. The pistons in this wheel rod set were designed to rotate faster for torque than the "equal speed" wheel rod set responsible for the travel of the rails.
On a railway line without rack and pinion, the gear is a useless load. But again, there may be some geared steam locomotives where the pistons driving the gears are linked to the pistons driving the wheel rails in order to avoid wasting power. However, given the basic simulation, we do not need to care whether these pistons are linked or not. In any case, it is sufficient to assume that the two sets of rods are acting together.
If there are toothed rail steam locomotives where the gear-driven piston and the wheel-rail-driven piston are coupled, this becomes a problem with only one wheel-linkage set.
哔哩哔哩 一侧有两组轮的蒸汽机车—印度阿三Nilgiri东南铁路 X 型蒸汽机车
哔哩哔哩 爬陡坡的齿轮链轨蒸汽机车 Mount Washington Cog Railway

[leezer3]

That's a very good point, although I'll note this is still a heavy WIP and experimental playground at the minute :)
It's basically ported from BVEC_ATS, although I've done considerable work (experimentation with numbers!) on stuff like the fire / boiler simulation properties.

As far as I'm aware I'm the only person to actually use the valve gear animation (the D51 uses a more 'conventional' frame based approach), and adding too many available variables may confuse matters, especially as this requires manual model parts and positioning.
I've converted the rod positions to an array though, and can probably do the same with the pivot locations. This might cut down on the number of required animation instructions too

[JunmoreHeavyBox]

The variables I'm considering are just custom things linked via indexes, similar to the indexes in the Extensions.cfg file... I think I understand the confusion caused by the index docking...

I am considering the same steam locomotive with all the animation objects used in the XML carriage file, which has nothing to do with the locomotive's carriage position in the train.
A train would probably use two axle-driven steam locomotives. I have not come up with anything about linking wheels across vehicles.

[ginga81]

The reason I chose frame-based on the D51 is because it didn't animate in 3D when the driving wheel slipped.
The wheels didn't move at all even though the speedometer was up when the driving wheel slipping.
Therefore, I gave up on the BVEC_ATS driving wheel calculation and decided to create 32 transparent PNGs and animate them.
However, with this, if you run it for a long time, about 30 minutes or more, the position of the driving wheel will shift, so if the driving wheel can be linked when the wheel slips animation even at 3D, I would like to make it in 3D.

[JunmoreHeavyBox]

I have a similar, but less obvious, question about the Speedometer variable for animated objects.
No. 7 in #821

[JunmoreHeavyBox]

Speaking of wheels synchronised across vehicles, how about adding [carIndex] after the variables for wheels and linkages?

The concept of a wheel and rod set is a bit confusing, I would like to approximate the composition of multiple steam locomotives in the traction model, where the final traction is a composite of the traction of multiple virtual steam locomotives. When any one set of wheels slips it does not interfere with the other wheels that are pulling properly. This is not only true for the animation.

Then just to talk about the "compound expansion steam locomotive", without seeking to implement it. If you let the train plugin control any virtual steam locomotive alone.
https://locomotive.fandom.com/wiki/Mallet_locomotive