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OR Steam Exhaust New Changes Rate Topic: -----

#301 User is offline   Traindude 

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Posted 05 July 2017 - 09:48 PM

Hi. I'd like to talk about something in regards to steam exhaust, and it's something I hinted at in a previous post.

Articulated (and some duplexes like the Pennsy S1) locomotives with twin stacks were often arranged so as to provide a separate stack for each pair of cylinders. This means that when the engine is in operation, instead of both stacks puffing at the same time, you get a distinctive alternating puff sequence. The main factor determining this is the difference in crankpin angles on both sets of drivers. For example, if the front set of drivers is closer to its "usual" 90-degree puff interval than the rear drivers, the front stack will puff first before the rear stack does.

The only operating twin-stack articulated as of today is UP 3985, but I have not seen any videos that make the alternating puff timing apparent, so I have taken the liberty of making a reference video using a simple (but crude) model in Blender to demonstrate what the puff timing looks like in various scenarios, including the effect of wheelslip on one set of drivers. Here's a still from it:

http://i.imgur.com/XIMEK0C.png

I won't be posting this to YouTube, since it's intended solely for the benefit of the ORTS development team, but if any deleopers are interested please PM me.

It should also be noted that even on articulated/duplex locos with only a single stack (provided they're either simple expansion or compound Mallets starting from a stop in "simple" mode), the same puff timing scheme holds true. The only difference is that, obviously, all puffs are coming out of only one stack.

And I know I'm getting ahead of myself...
...but it would help of both sets of drivers were part of the same .s and .eng files!

#302 User is offline   ATSF3751 

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Posted 04 February 2018 - 12:26 PM

Any thought of fixing up the Steam exhaust all. Would make a world of difference to at least get the puffing synced with the wheel rotation and cylinders. Along with fixing up cylinder steam so it blast out.

Brandon

#303 User is offline   darwins 

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Posted 05 February 2018 - 12:39 AM

From what I have seen and heard regarding Garrats and Fairlies the 'puffs' are not so much alternate as independent - that is if one set of wheels slips a little or takes a curve differently in will move slightly more into or out of sync with the other set of wheels, so that at times the exhaust beats might be alternate and sometimes they might be together or nearly so. Would this be the same with the US engines you are describing?

Also you would need a sound set with two independent engines as well - not sure if you could match them well to the wheels in the animation or make them go slowly into and out of synchronisation - it seems like a difficult thing to achieve.

#304 User is offline   vince 

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Posted 05 February 2018 - 11:15 AM

Musings over morning coffee . . .
Drive wheel sets on a steam engine like a Pacific K4 cannot get 'out of sync' as the left and right side are joined by a solid axle. The drive wheels are precisely timed so the drive rod pinyons are 90 degrees apart from drive wheel on the other end of the axle. 'Quartered' is the term.

Many MSTS steam engine models I notice do not have properly quartered drivers. This is nothing more than a modeler either not understanding how it's done is pure lazyness or inattention to prototypical modeling. These 'models' I consign to the trash bin on the theory that if the modeler does not care how an engine looks then I consider it junk.

A compound (or dual?) engine with two sets of drive wheels and cylinders is actually two steam engines sharing a single boiler. The 'Challenger' is an example.

So a single engine, lets use a Pacific K4 type, can never get 'out-of-sync'! If it did it has a very serious problem.
An engine like the Challenger can get out-of-sync as it's actually two engines. How to model sounds for that is a poser.
Maybe the answer is the engine 'chuff' sounds linked (synced?) to drive wheel diameter and speed?

regards,
vince

#305 User is offline   Traindude 

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Posted 06 February 2018 - 10:19 PM

View Postdarwins, on 05 February 2018 - 12:39 AM, said:

From what I have seen and heard regarding Garrats and Fairlies the 'puffs' are not so much alternate as independent - that is if one set of wheels slips a little or takes a curve differently in will move slightly more into or out of sync with the other set of wheels, so that at times the exhaust beats might be alternate and sometimes they might be together or nearly so. Would this be the same with the US engines you are describing?

Also you would need a sound set with two independent engines as well - not sure if you could match them well to the wheels in the animation or make them go slowly into and out of synchronisation - it seems like a difficult thing to achieve.


I am only referring to engines with TWO smokestacks. It was a common practice on some latter-day articulated steam engines to provide s separate smokestack (chimney) for each pair of cylinders.

When the engine is in operation, and angular difference between the crankpins on both the front and rear drivers is 0, 90, 180 or 270 degrees, then both stacks will puff at the same time. If the angular difference is anything else, then instead of both stacks puffing at the same time, the puffs will alternate between the two stacks.

Since a two-cylinder simple rigid frame engine "puffs" whenever the crankpins reach, say, 3, 6, 9 and 12 o' clock, then all it means that if the crankpins on the rear set of drivers hit say, 3 o'clock before the crankpins of the front set of drivers do, the rear stack will puff first before the front one does.

PM me if you wanna see my video, it'll explain it better.

#306 User is offline   ATSF3751 

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Posted 08 February 2018 - 04:26 PM

Here are some examples of how smoke and Steam should act in Open Rails. One thing that I have noticed with the real world VS Open Rails is the smoke rises much higher in the real world VS Open Rails. There have been times where I have been running steam locomotives full bore on Open Rails and smoke ends up in the passenger cars or the cab of the locomotive and that should not be the case. Another thing that really bothers me with Open Rails and even MSTS is that the Cylinder smoke does not blast out of the sides like it should. It kind of just streams out if you know what I mean. Another thing is the Blast Effect that steam locomotives give off especially when first starting out. I think the Open Rails Team is doing a great job overall but seeing that I run Mostly Steam its really lacking in some areas. I think the smoke for steam locomotives needs to be totally re-coded so different smoke can be used in different areas. The Open Rails team does have some stuff going for it though with Steam Locomotives because I like the way it looks just not the way it acts a lot of times. Also like how it interacts with the throttle. The more the throttle is open the more that comes out along with the way it acts with the Fireman depending on how they are firing. Here are some videos I have put the links into. The first video is of the Iowa Interstate Qjs Double Heading a long freight in MSTS and the Second Video is of my Milwaukee Road 261 pulling an excursion in Open Rails to kind of give you an idea of what I am talking about. The other videos are of different steam locomotives Including the Milwaukee Road 261 in the real world just to give you some examples. I think if these minor changes where made it would make a huge difference in the way the smoke looked.

Brandon

https://www.youtube....h?v=EEZpqh__t0o

https://www.youtube....Q9G-VzN8&t=146s

https://www.youtube....h?v=kF-k_bNI9xA

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

https://www.youtube....h?v=AFNF1v9s-J8

https://www.youtube....hEce1Wwo&t=945s

https://www.youtube....fxYut4MXgI&t=4s

https://www.youtube....h?v=yjXOiHkeOC8

https://www.youtube....h?v=lmrJ3wiY0nM

#307 User is offline   captain_bazza 

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Posted 09 February 2018 - 12:27 AM

Great ideas. However, we were warned (cannot remember by whom, or when exactly) that particle displays were heavy on processing resources.

Cheers Bazza.

#308 User is offline   copperpen 

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Posted 09 February 2018 - 02:30 AM

The main things missing are velocity of exhaust while the locomotive is stationary, and a distinct lack of lift to the exhaust when moving. The only sim to show these so far is MSTS.

Personally I am not really fussed about linking exhaust chuff to cylinder movement, that takes up processing power that can be used elsewhere such as linking the cylinder pressure relief where used to the cylinder movement and adding some velocity to the steam from the cylinder drain valves. They will both need their own set of code for particle movement because they are both completely different to the normal exhaust and different to each other.

#309 User is offline   ATSF3751 

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Posted 11 February 2018 - 11:55 AM

Yes I agree with you Copperpen and I think that would make a world of difference. Here are some ideas from TRAINZ that I think would be great if Open Rails included in it as well. I am NOT Saying to copy exactly what Trainz has but some of there concepts are really neat. Also notice how the smoke is in Trainz VS Open Rails. They have some what of the concept but I feel Open Rails could do even better. The open Rails team is doing a wonderful job and seeing where it has taken MSTS and made it 1000 X better gives me hope to see what else can be done! Another thing is computers now a days are way more powerful then back when MSTS was invented so I feel the Open Rails team can cut some slack when it comes to trying to keep things down. I understand we want to cut down on some things but the models now a days are getting so much more detail that I feel the game should be the same and try to also make it look as realistic as possible. The physics are wonderful but thats only half of it because visual effects are also a huge part of the gaming experience. Just something I look at when running Open Rails. I do think Open Rails though has a lot going for it and a lot of the other sims beat in many areas though including physics and many other aspects it just seems that realism is kind of being missed in a way.

Brandon

https://www.youtube....LjO-13E8&t=318s

#310 User is offline   ATSF3751 

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Posted 23 February 2018 - 04:21 PM

This is what the Open Rails team needs to do is the stack smoke needs to be linked to the throttle along with the Wheels. Then the Cylinder and other appliances need to have completely different smoke effects. I think the Open Rails Team has it good for the way the smoke performs depending on firing but it looks very tacky and unrealistic the way it performs when it comes to being so low and not having it be effected by the puffing and another thing that needs to effect it is the blower depending on how much you have it on! This is just my input since I have been around Steam practically all my life and know how it should perform fairly well. This is one of the big downsides to Open Rails I think and feel it needs to be worked on.

Brandon

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