[steamer_ctn]

copperpen, on 05 March 2024 - 03:12 AM, said:

Cylinder cocks and other items are different in that they should have a continuous emission when opened, not puffs like the stack so should be coded differently with the exception of the air brake pump which also used a reciprocal piston.

That is an interesting comment.

I was under the impression that when the locomotive is stationary, then the cylinder cock exhaust would be continuous. When the locomotive is moving the the cylinder cock exhaust will alternate between the front and back of the cylinder. In some instance it may appear "continuous" if the exhaust is a common point.

Jonatan, on 05 March 2024 - 11:19 AM, said:

All I do know is that nothing will happen unless someone decides to do something, and everyone are busy focusing on their pet projects.

So is this your offer to do something and put your pet project on hold?

Jonatan, on 06 March 2024 - 11:02 AM, said:

Smoke physics is such a complex and dynamic thing that I doubt any simulator could recreate it perfectly. There's a million and one factors ranging from wind conditions, air humidity and density to weight of individual particles that determine how the smoke forms, behaves and moves. Even temperature and elevation affects smoke behavior!

I agree that it is very complex, and the amount of effort required to produce an outcome may not always be worth the effort.

To understand whether any potential improvement can be achieved it is necessary to understand some of this complexity. For what seems to be a simple change on paper, or from a Youtube video, may be quite a complex feature to simulate in a virtual environment.

So within OR the smoke, steam effects, etc are created by two complimentary software modules as follows:

i) Particle Emitter - creates the actual smoke (steam) appearance in the simulated world. So the look and movement of smoke with wind, and as the train moves, under different atmospheric conditions, etc is controlled by this module. For example, the issue of the smoke moving forward of the stack with increased train speed is an issue within the Particle Emitter (I think).

ii) OR steam (and diesel) physics code - The physic code determines when smoke (steam) should appear (ie when a steam exhaust is turned on), and how much smoke or steam is generated, etc (NB: at the moment there is not necessarily a direct relationship between the real amount generated and how the particle emitter displays this amount in the virtual world).

I believe that there are some potential tweaks that could be done to the physics code that may make the performance somewhat more realistic (not necessarily more visually appealing).

I am willing to do some of these tweaks for the steam locomotive, if there is a level of interest, however it would need to be on the understanding that we are hoping for an improvement, but recognising that it is unlikely that we will get a 100% perfect outcome. Complimentary changes would need to be done in the Particle Emitter, however these changes are out of scope for this offer.

So it would need to be accepted that were the line is eventually drawn is where it is drawn, and may not go further within this project. The other point is that it will be done within my timeframe.

copperpen, on 06 March 2024 - 06:25 AM, said:

I think we can do better if we use the cylinder backpressure instead of speed to drive the smoke steam.

I don't believe that the calculation of the cylinder backpressure is very robust, and therefore it is not a good reference parameter for stack smoke.

Bear in mind that we have two effects in OR combining, ie the smoke (created by fuel combustion) and the exhaust steam (created by steam). I am not sure if MSTS modeled both of these streams independently?

We would need to identify good quality physics parameters that emulate the operation of the locomotive as closely as possible. Hence I would suggest that the cylinder steam usage is a better reference parameter (certainly for the steam exhaust) as this changes depending upon how hard the locomotive is steaming.

[darwins]

Quote

Bear in mind that we have two effects in OR combining, ie the smoke (created by fuel combustion) and the exhaust steam (created by steam). I am not sure if MSTS modeled both of these streams independently?

We would need to identify good quality physics parameters that emulate the operation of the locomotive as closely as possible. Hence I would suggest that the cylinder steam usage is a better reference parameter (certainly for the steam exhaust) as this changes depending upon how hard the locomotive is steaming.

Cylinder steam usage certainly makes sense for the amount of steam in puffs.

The quantity of smoke should depend upon draught. This is a combination of natural draught (usually small), draught from blower, draught from ejectors (in UK vacuum braked locos), and cylinder exhaust.

Now that you have a very good physics model of individual cylinder exhausts this could probably be applied to the smoke - each puff if steam is going to increase the draught and draw a quantity of smoke with it. From obervation, although the start of the puff is sharp, the steam and smoke mixture than seems to fade in quantity rather than coming to a sharp end and leaving a gap before the next puff. * As shown by exhaust pressure line in diagrams below *https://i.imgur.com/17C5JZu.png

The action of the blower / ejector exhaust up the chimney does not seem to produce a great deal of visible steam in most circumstances, but the real life visual effect is more like just the smoke increasing in quantity and velocity due to the increased draught.

Quote

Complimentary changes would need to be done in the Particle Emitter.

I am hoping someone with the skills and abilities to look at this will come along at some point. It is not just smoke and steam behaviour that could be improved, but also water particles.

[Laci1959]

Hello.

A little help for Peter.
My link

You can clearly see the steam coming out of the cylinder heads in close-up at about 5:54. The video was made in 2009 on the route to Vienna of the Southern Railwa locomotive number 109.109.
Southern Railway: k. k. private Südbahn-Gesellschaft / cs. kir. szab. Déli Vaspályatársaság

Sincerely, Laci 1959.

[Jonatan]

Quote

So is this your offer to do something and put your pet project on hold?

My comment was more of a statement than a complaint, Peter. I'm very well understood that people are busy with other things of greater personal interest than what we the users are asking for. This is the nature of volunteer work that I, as a railroad volunteer, am well aquainted to: Unless I pay you, I am in no position to demand anything.



Something that came to me while having my dinner nap; we have advanced diesel exhaust parameters that allows us to determine how it behaves, color changes etc.
Perhaps, at a later date when it is convenient, it would be an idea to give steam smoke and exhaust its own similar set of advanced parameters for user fine-tuning?

[Weter]

Hello.

Jonatan said:

Smoke physics is such a complex and dynamic thing that I doubt any simulator could recreate it perfectly. There's a million and one factors... <which> affect smoke behavior!

Peter said:

I agree that it is very complex, and the amount of effort required to produce an outcome may not always be worth the effort.
To understand whether any potential improvement can be achieved it is necessary to understand some of this complexity.

What I've realized, studying how other's content made and trying to make my own:
any simulator is simulator (this was stated here many times too), but talented or lucky author can guess, which detail is most critical, in giving players the impression of the real thing (IOW, driving them to believe - the thing in game is real-like) While actual performance remains more or less schematic.

I mean - it hasn't sence to look for ways of modelling all and every aspect of smoke, instead, just try to figure-out, why real smoke is recognized as a smoke and try to reflect that.
I guess, Peter have meant something like that, am I right?
Just one single substance - sodium glutamate induces impression of meat's taste of tasteless meal.

[ATSF3751]

So I took the liberty of installing MSTS back onto my PC just to see if I can try and crack the way Microsoft did the smoke. Unfortunately I do not think there is a possible way of figuring it out but I do have to give Microsoft props for how well done MSTS is for its day and installing it back on my PC has brought me back to my childhood. Sure the graphics were not the best but they did get a few things right like smoke, wheel slip, along with many other things that were the pioneer to today's Train Simulator games!

They even had animations in the passenger cars and that just shows the kind of time and effort was put into the game even back then.

It has also given me a new appreciation for what the ORMT and Open Rails has done in general for the MSTS community. We have come a very long ways from MSTS days 23 years ago but still have some should I call them "kinks" to work out.

Another thing I noticed and really like is the way MSTS did there F5 key. Showing everything from general operations to back pressure, steam usage and more but it seems to be in much simpler terms then Open Rails is currently and Open Rails seems to be missing some components in that area that MSTS has.

When it comes to Smoke and comparing MSTS to Open Rails it seems like we are missing a few things. In MSTS the smoke seems to be much more fluent and in a stream the faster you go VS Open Rails where it is puffs and very sporadic the faster you move. Anther thing we are missing that MSTS has is the smoke does not seem to go through objects at all but instead bounces off of objects unlike Open Rails where the smoke goes through everything it touches. One more observation I had while running the Flying Scotsman and Orient Express is how well MSTS does with draft when sitting still. Just a few observations I had while playing the game.

Brandon

Here are a few MSTS Screenshots

[steamer_ctn]

Jonatan, on 07 March 2024 - 08:54 AM, said:

My comment was more of a statement than a complaint, Peter. I'm very well understood that people are busy with other things of greater personal interest than what we the users are asking for. This is the nature of volunteer work that I, as a railroad volunteer, am well aquainted to: Unless I pay you, I am in no position to demand anything.

Ok, thanks for clarifying this, however these sorts of comments about "pet" projects can be taken the wrong way, especially as EVERYBODY in the OR community CAN play a part in the development of OR, and we shouldn't single out one group over another, and make these sorts of "accusations". I sure that a lot of others in the community have pet projects as well which they could set aside to contribute to their skill expertise if they felt inclined.

darwins, on 07 March 2024 - 03:23 AM, said:

Cylinder steam usage certainly makes sense for the amount of steam in puffs.

The quantity of smoke should depend upon draught. This is a combination of natural draught (usually small), draught from blower, draught from ejectors (in UK vacuum braked locos), and cylinder exhaust.

Now that you have a very good physics model of individual cylinder exhausts this could probably be applied to the smoke - each puff if steam is going to increase the draught and draw a quantity of smoke with it. From obervation, although the start of the puff is sharp, the steam and smoke mixture than seems to fade in quantity rather than coming to a sharp end and leaving a gap before the next puff. * As shown by exhaust pressure line in diagrams below *

The action of the blower / ejector exhaust up the chimney does not seem to produce a great deal of visible steam in most circumstances, but the real life visual effect is more like just the smoke increasing in quantity and velocity due to the increased draught.

I agree that we need to consider the two effects separately, and then see if we can blend them together a bit more realistically.

I want to reflect upon the physics a bit, and then make a few changes to see if we can get any improvement.Again, it may not be the same as MSTS or Youtube, but we need to be happy if we get an improvement.

[Weter]

Sure. Water will never flow under layind stone. It have to move somehow.
Unlucky attempt is better, than absence of activity.
The road will be made by the one, who walks.

[copperpen]

When I said that the cylinder cock steam is continuous I was not referring to the alternate streams from each one, but rather the stream as seen within OR. If you look at the visuals in OR the steam from the cylinder cock comes out in very rapid puffs from each origin point where it should be a steady stream with no puffs from each origin point when active, something else to look at later on after the main smoke/steam is sorted out.

Quote

I don't believe that the calculation of the cylinder backpressure is very robust, and therefore it is not a good reference parameter for stack smoke.

Bear in mind that we have two effects in OR combining, ie the smoke (created by fuel combustion) and the exhaust steam (created by steam). I am not sure if MSTS modeled both of these streams independently?

I do not think the robustness of the backpressure calculation should prevent the exploration of using this parameter to drive the visual exhaust. Far as the modelling of smoke/steam goes. MSTS only used one ace file for both and changed the colouring for the duration of burning the volatiles thus giving the alternate white and dark exhaust, As far as actual firing is concerned they also used a simple on/off system based on the firebox "volume" with a "low level" and a "high level" to turn the AI fireman on and off. That I believe is the best way to mimic the normal firing rhythm of "little and often". This depicts the rapid burn of the volatiles ( grey/dark smoke ) and the slower burn of the carbon element of the coal ( very light grey to white steam )

[Traindude]

Based on my personal observations, I would like to add that the design of the smokestack also has an influence on the velocity of the exhaust steam. This is especially true for locomotives with balloon-, diamond- or funnel-shaped smokestacks used with wood-burning (and some coal-burning) locomotives.

Experiments of the flow of gasses containing small particles proved that, as the exhaust steam and firebox gasses passed upward into the conical or tapered section of these stacks, the velocity of the gasses was significantly reduced to the point where any buoyant embers in the firebox gasses would fall back down into the smokebox (this is in addition to the embers that are caught by the spark screens). This also visibly reduces the velocity of the exhaust blasts emanating from the stack.

Here's some videos to demonstrate the difference:

Locomotive exhaust steam blasts with straight smokestack (0:12-0:19)

Locomotive exhaust steam blasts with diamond smokestack & external spark screen (0:24-0:33)