[Traindude]

Sorry to bump this thread, but I have made a couple observations regarding steam exhaust:

Observation #1:

You've probably noticed that large articulated simple-expansion locomotives, such as the UP Challenger, Big Boy, the C&O Allegheny and some of SP's cab-forwards have twin stacks. The reason for having twin stacks on an articulated is usually to give each pair of cylinders their own stack. So, the front cylinders exhaust through the front stack and the rear cylinders exhaust through the rear stack. What this means is that, depending on how the two sets of driving wheels are rotated, instead of both stacks puffing simultaneously, the stacks puff alternately. So when you hear "Ch-chuff...ch-chuff...ch-chuff" the stacks puff in an alternating "front-rear...front-rear...front-rear" or "rear-front...rear-front...rear-front" pattern depending on the locations of the crankpins on one set of drivers in relation to each other.

Observation #2:

I have noticed after seeing Santa Cruz Portland Cement #2 at the Northwest Railway Museum in Snoqualmie, Washington, that if auxiliaries such as air pumps, mechanical stoker engines and booster engines exhaust into the main exhaust nozzle in the smokebox or even the exhaust passages in the main cylinder saddle, the operation of these devices influences the velocity of the stack emissions, but not the density. This is most obvious when the locomotive is at a standstill. I have found no logical explanation for this. Maybe it is because the exhaust produced by these auxiliaries has minimal effect on the draft when the engine is idling than the exhaust from the main cylinders has.

Of course, the air pumps do not always discharge into the exhaust passages or exhaust nozzle. If the locomotive has a feedwater heater, then chances are the pumps exhaust into the feedwater heater to allow some steam to heat the water even when the main cylinders are not working. Or, it may discharge through a separate pipe which may be next to the main stack, or even clamped to the inside or outside the stack, in which case you would see white plumes of steam in time with the air pump sounds, (here is an example)

[copperpen]

I have been doing a bit of research into the speed of flue gas, and the exhaust. The exhaust itself is a really complicated thing to properly replicate with different speeds dependent on where in the plume you look. The highest speed will be in the centre and it is this that gives the initial velocity and lift to the exhaust plume. It has been mathematically calculated that running under normal conditions the centre velocity is in the region of 529MPH ( 236 m/s ) whereas the edge velocity where it is slowed by friction with the stack, can be in the order of 79 mph (35 m/s ). The flue gas from the firebox is estimated to travel at about 65 mph ( 29 m/s ) pulled along by the vacuum created by the exhaust. This is based on a steam output of 18000 to 20000 lb/hr. and therefore can be higher or lower depending on how hard the locomotive is working.

At rest, flue gas is calculated to leave the stack at about 17mph, roughly 7.5 m/s. Based on those figures, the OR steam exhaust does need an overhaul.

[ATSF3751]

Yes I also agree that Open Rails exhaust needs to be overhauled. Here are some clips of the Milwaukee Road 261 and a few other steam locomotives here in the USA. I think before we start with double stacking and all that we should try and get the smoke figured out first. Also the smoke changes colors depending on many different factors. Another thing to keep in mind is if you have the blower on, how much the locomotive is laboring/pulling, how much the throttle and regulators are open/closed, how its being fired, temperature and weather could also play a factor on how the smoke looks as well. If its cold and damp more steam is present. If its hot and dry there is usually less smoke coming from the locomotive. Just a few things to consider while revamping steam/smoke on steam locomotives. Also the Cylinder Cocks need a lot of work as well as they seem to just not even blow out of the cylinders and just make a big cloud of steam where the cylinders are. One thing I have really noticed also is that when a steam locomotive is at full throttle the smoke just hangs low in the air and does not lift up like it should. It almost looks like its laboring really hard but with absolutely no draft to lift the smoke up in the air in open rails.

Brandon

https://www.youtube....h?v=tA39MuCtgzQ

https://www.youtube....h?v=d9uLa1aP8-g

https://www.youtube....h?v=5t-qZv0Hmok

https://www.youtube....h?v=Xuri8Htb2V4

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

https://www.youtube....h?v=juPRFV0XKlU

https://www.youtube....h?v=lKe9ckYLWWA

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

https://www.youtube....h?v=parXuIch1ZA

[ATSF3751]

I know this is hard to replicate but this is how I would love to see the smoke in Open Rails eventually. I am not saying exactly like that because I believe Open Rails can do even better but that would be an idea on how it should look.

http://www.kltrainz.com/videos.html

https://www.youtube....v-ZzswJKFwl6EQP

https://www.youtube....v-ZzswJKFwl6EQP

[captain_bazza]

IMPRE S S I V E!

CB.

[copperpen]

I would not like to see Open rails steam stack effects look like those videos. The current method used in OR could do with a good reworking, but lacks someone to write the code for it. The main problem is that we have one particle system that covers all outlets whereas in reality the steam coming from a generator, injector, ejector, and the cylinder drain cocks are all different and completely unlike that which comes from the stack. This requires each type of orifice to be coded separately do give the different styles of effects. Something that MSTS seems to achieve.

[ATSF3751]

Yes I agree the smoke/steam need a major overhaul and thought these videos would help with how it should really look and work for starters that is in the new Trainz. I think Open Rails could do even a better job with steam and smoke effects if given the time and effort. To be honest I'm not a fan of Trainz but when I saw the way they had the smoke I was somewhat impressed the way they had the Chuffing when a steam locomotive first starts out. Looking at videos of the new Trainz it seems like the smoke is too blocky when it first comes out of the stack and its like just a big trail of smoke following the locomotive with no real wind effect like Open Rails has so for me it would be nice to see a version that has a little bit of both combined for Open Rails. Anyone else have any thoughts on this?

Brandon

[copperpen]

I would like the stack effects to be driven by the pressure of the steam leaving the cylinder and generating the escape velocity which is then modified by the forward motion of the engine for direction. So slow speed and hard work generates a tall exhaust plume, but at the opposite end of the scale, high speed will show a lower plume with a backward "curve". A standing locomotive also needs to have a higher than present exhaust plume, after all, it is generated by the fire and we all know that hot air rises, it does not hang around the stack and come out in puffs.

[ATSF3751]

Yes another thing to put into play is the blower. When a locomotive is standing still the blower is usually on and it would be nice to see the smoke change depending on how much the blower is on or off.

[CrisGer]

I noticed this thread and wanted to thank the ongoing discussion. I agree with other posters that the KL trains videos show rather aritificial smoke effects and i would NOT like to see that approach imposed on Open Rails.

At the end of our development of the steam cycle of textures for MSTS we achieved a very good result. It took years of adjusting. I hope we can reach that sort of result with Open Rails and I invite any who want to try them to try the textures attached below that I developed working on top of others' work over the years for MSTS.

I remain hopeful we can reach a good level of delivery for OR>

One important aspect of steam smoke is that it emerges in quite crisp shapes that are ephemeral, in that they flow and change very fast but the texture cycle needs to have some hard edged almost sharp edged shapes in the cycle to look realistic. I do not know how the particle effect delivery works in OR but this set of textures for MSTS and the pictures can share what I feel is a good approach... it may also work for the steam cock delivery but that is another issue.

where a lot of simulators fail in this issues is that they use a fuzzy and vague steam shape essentially a smudge system and it simply does not look at all realistic. For a sim to work well, it has to have good detail, high detail often esp on the rolling stock, buildings and the environment including realistic shading, weathering and unique texturing not universal tiling and delivery of flat colours and effects. I feel Open Rails does this and can do this.

Chris

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Attached File(s)

•  SPECIAL SMOKE.zip (1MB)
  Number of downloads: 744