[Weter]

Very interesting.
Didn't know about two, but have seen on some ones, starting from MSTS default Royal Scot - the oval chimneys, instead of usual round.
The engine, I badly remember in association with four chimneys might be purple painted, or I mess it with Duchess... Or that was just a dream, combining all my daytime impressions in quite an odd way...

[darwins]

Rebuilt Royal Scot is a double blast pipe and chimney.
https://www.brassmasters.co.uk/images/Gallery%20-%20Scot/6153%20GH%20front.jpgSee http://www.greatwest...g.uk/basic9.htm
The Kylchap blastpipe is described here https://en.wikipedia.org/wiki/Kylchap

There are some oval chimneys as well, these use an exhaust system called a Giesl ejector. https://en.wikipedia...i/Giesl_ejector

[Weter]

Thanks a lot to Darwin as well. Now I see.
Certainly, original MSTS didn't represent that.
But it's great, we can define multiple stack fx.
I wonder, Are the real smoke plumes from such stacks similar with each other, or have differences, as Brandon suggested about T1?
Great model by the way. I guess, way too expensive, but likely the dream of many to have!
Even the weathering is seen.

[Traindude]

Weter, on 25 February 2024 - 01:55 AM, said:

Thanks a lot to Darwin as well. Now I see.
Certainly, original MSTS didn't represent that.
But it's great, we can define multiple stack fx.
I wonder, Are the real smoke plumes from such stacks similar with each other, or have differences, as Brandon suggested about T1?
Great model by the way. I guess, way too expensive, but likely the dream of many to have!
Even the weathering is seen.

On locomotives like this, which have all their driving wheels driven by one group of cylinders (non-duplex/articulated) and that have multiple stacks, the exhaust usually come out of both (or all) stacks at the same time.

[ATSF3751]

Here is an example of what Traindude and I are talking about!

The UP 844 UP 3985 and UP 4014 have two stacks and here are videos of all three of them starting out from a dead stop! See the difference in the smoke?

UP Big Boy 4014 4-8-8-4- https://www.youtube....h?v=UYYzhjUzCOU

UP 3985 4-6-6-4- https://www.youtube....h?v=cq7mrqFbMn4

UP 844 4-8-4- https://www.youtube....h?v=BY_iCND1pRY https://www.youtube....h?v=O8BXipiLfwA

[ATSF3751]

Here is something that maybe Open Rails should look into. May be a good way to incorporate Manual Firing!

https://www.youtube....h?v=E0b38E9reV0

https://youtu.be/xs7...mibextid=NOb6eG

[Traindude]

ATSF3751, on 04 March 2024 - 12:58 PM, said:

Here is something that maybe Open Rails should look into. May be a good way to incorporate Manual Firing!

https://www.youtube....h?v=E0b38E9reV0

https://youtu.be/xs7...mibextid=NOb6eG

That first clip looks like it could be useful in the future--the problem is finding people willing to code for it.

In the case of locomotives with mechanical stokers, adjusting the distributor jet pressures would likewise have a bearing on how the firebox reacts.

[copperpen]

Having read through the thread I feel that the original concept proposed is way too complicated. Microsoft in the original MSTS made a very good job of representing different types of steam emissions using one ace file with steam and smoke happening together. Smoke was generated when fuel was put on the fire, steam was generated while the engine was in motion. The volume of emissions from the stack were controlled by the positions of the throttle and cutoff. The stack emissions did not vary in location either. They also managed to produce a cylinder cock emission which was fairly good using the same ace file. All of this suggests to me that there is a serious amount of coding required to arrive at where we would like to be and there is zero requirement to go down the Blender rabbit hole or the even bigger one of multiple types and styles of smoke/steam.

First step is to nail down what is causing the stack emissions to move from the point of origin as speed increases. Following along from that Peter has developed a very good basic representation of firing and steam generation. To get our steam visualisation to look reasonably good we need this concept to be developed further to allow for proper manual style of AI firing which was not too shabby in MSTS. There is also then a need to develop a system whereby a draft is applied to the fire at all times which then produces a continual exhaust emission at the stack from the fire. At rest this system would produce a basic draft much like a fireplace in a house. Application of a blower would increase the draft thereby improving the heat from the firebox by increasing the vacuum in the smokebox. Once the engine is moving this vacuum is provided by the exhaust steam.

Moving on to the visual representation, the volume should be controlled by the throttle and reverser positions while the movement out of the stack should be controlled by the cylinder exhaust pressure and the application of a vertical speed element to the exhaust which is also affected by the relative speed of the engine. Therefore the lower the pressure allowed into the pistons the lower the speed of the exhaust will be thus affecting both volume and vertical lift.

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.

What this all boils down to is how we manipulate our sprites.

[Weter]

collision with static obstacles above tracks
dissipation wind-caused drift

[Jonatan]

I agree with Copperpen on all points. There's alot of dunking on MSTS physics etc but the smoke was quite good all things considered.
Complicating things for the sake of complexity itself is a self-defeating goal, sometimes simplicity offers a better solution, if one looks for it.

I don't know what KUJU nailed that we're missing, and we'll probably never know. All I do know is that nothing will happen unless someone decides to do something, and everyone are busy focusing on their pet projects.

A few old screenshots from MSTS, the continuous stream of steam from e.g.: safety valves even at good speed is indeed professional for something 20+ years old.