[Matej Pacha]

IMO, we are creating some kind of fake world in every simulator (in general). As far as present computing has some limitations we need to simplify our models of real world, more or less. In every simulator the main part is the one of the main purpose - in FlightSim it's aircraft physics, in rallye sim it's car physics. Some parts of these models are simplified to keep CPU load low but to keep players' impressions. Yes, ORTS is now on its good way to a realism. But what is its main purpose? To create a real-world-based engine-driver simulator or to create virtual 3D model railway for those without money/place/time for a hobby of theirs?
ORTS is going to have many features from real world what is one of the most complicated and complex transport systems (rails, weather, many locomotive technologies, dispatcher systems, many national differences, etc.). Thus, ORTS needs to focus on some features and has to suspend those out of the main purpose. I would love to have a simulation with harmonic rocking, sinusoidal wheel oscilations, wind impact, ice on wires, load dependent voltage drop on the line, etc. I think we can always start with some simplified models without animations but simplification is always much more harder than direct implementation - you need to know the whole process and a metodology how to simplify it with acceptable impact on realism. If you know how to do it or wanna help, you are welcomed.
I just don't want to let this discussion to fly out to heaven of train simulators ;o)

Matej

[Genma Saotome]

Question for you Bill: Can rocking be simulated solely by movement of the car body or is the compression of truck springs a necessary visual component to make things look right?

[cjakeman]

Matej Pacha, on 25 November 2011 - 12:49 AM, said:

Thus, ORTS needs to focus on some features and has to suspend those out of the main purpose. I would love to have a simulation with
[snipped]
If you know how to do it or wanna help, you are welcomed.

And I would like to improve the behaviour of road vehicles. I'm looking forward to us reaching OR v1.0. After that, it will worth considering extensions.

[Lindsayts]

Matej Pacha, on 25 November 2011 - 12:49 AM, said:

IMO, we are creating some kind of fake world in every simulator (in general). As far as present computing has some limitations we need to simplify our models of real world, more or less. In every simulator the main part is the one of the main purpose - in FlightSim it's aircraft physics, in rallye sim it's car physics. Some parts of these models are simplified to keep CPU load low but to keep players' impressions. Yes, ORTS is now on its good way to a realism. But what is its main purpose? To create a real-world-based engine-driver simulator or to create virtual 3D model railway for those without money/place/time for a hobby of theirs?
ORTS is going to have many features from real world what is one of the most complicated and complex transport systems (rails, weather, many locomotive technologies, dispatcher systems, many national differences, etc.). Thus, ORTS needs to focus on some features and has to suspend those out of the main purpose. I would love to have a simulation with harmonic rocking, sinusoidal wheel oscilations, wind impact, ice on wires, load dependent voltage drop on the line, etc. I think we can always start with some simplified models without animations but simplification is always much more harder than direct implementation - you need to know the whole process and a metodology how to simplify it with acceptable impact on realism. If you know how to do it or wanna help, you are welcomed.
I just don't want to let this discussion to fly out to heaven of train simulators ;o)

Matej

For what its worth I completely agree here. It would be nice to see a lot of the things requested on various forums but there is little worse in a simulator than something that has been not done well or to simplified. The human mind is usually very good at picking if something has not been done correctly. Look at for instance the animation of people walking its easy to see if it is not life like.

Lindsay

[Lindsayts]

Currently there is a couple of things I would like to see improved. The first is steam consumption in superheated steam locos is some what over double what it should be for the power output of the loco. The second item is better sound timing particularly for exhaust release and also for geared locos, currently not realistic for Shays and Heisler,s

Hmmmmmmm Since I mentioned it, better handling of the "physics" for articulated locomotives. Including machines with two engines, Mallets and Garrats and other locos with one engine driving multiple bogies, ie Shay, Heisler and Climax.

Lindsay

[longiron]

Lindsayts, on 25 November 2011 - 12:34 PM, said:

Currently there is a couple of things I would like to see improved. The first is steam consumption in superheated steam locos is some what over double what it should be for the power output of the loco. The second item is better sound timing particularly for exhaust release and also for geared locos, currently not realistic for Shays and Heisler,s

Hmmmmmmm Since I mentioned it, better handling of the "physics" for articulated locomotives. Including machines with two engines, Mallets and Garrats and other locos with one engine driving multiple bogies, ie Shay, Heisler and Climax.

Lindsay

All being currently worked on. We've figured out how to get around that many MSTS locomotives are configured with 2x volume of the cylinders to get the water consumption correct. That's why you are seeing 2x steam consumption in OR. It's calculating properly based on the MSTS input parameters.

[Lindsayts]

longiron, on 25 November 2011 - 01:53 PM, said:

All being currently worked on. We've figured out how to get around that many MSTS locomotives are configured with 2x volume of the cylinders to get the water consumption correct. That's why you are seeing 2x steam consumption in OR. It's calculating properly based on the MSTS input parameters.

Thanks for the info, its much appreciated,

Briefly experimenting on the above shows the CylinderVolumne as interpreted by OR is the volumne of one side of a single clynder. ie for a cylinder of bore 21.5 in and a stroke of 28 in this the CylinderVolumne is 5.82, I assume OR is expecting the parameter in cubic ft ie ( "5.82*(ft^3)"). The steam consumption is still a little high requireing around 30% more than reality to get the required drawbar hp. When one throttles back at high speed to stay within the boiler supply figures the tractive effort and drawbar power figures drop out of site, this is something I believe should not happen.
Note: At this stage its not worth worrying to much about it as its is a development version that has been out for sometime now.

Lindsay

[Matej Pacha]

Turbo Bill, on 25 November 2011 - 02:33 PM, said:

Body only: For one when the car is empty the springs are so strong that no compression occurs at all. This is reason they rock and jostle around so much especially on jointed rail. Loaded, the springs are compressed so much that they have little play left for heavy irregularities in the track structure or "plant" as the MOW forces refer to the tracks, ballast, etc. as a whole. But what little play there is, about 1-2 inches depending on load weight diminishes a lot of the rocking motion. Cars whose loaded weight is about 1/2 of total allowed weight ride the smoothest as you now have half-compressed springs that have sufficient travel distance between fully compressed and fully stretched. Also the springs rust exactly the same color and degree as the rest of the truck, the only exception is if the truck main structure itself is painted, usually black making them really hard to notice any movement. Also the total travel distance of the spring from full stretched state (empty) and compressed state (fully loaded) is only about 6-8 inches. You couldn't see it even if you watched them. But you do hear it, that is the deep groaning sound you hear from loaded cars as they go by at slower speeds like 10mph and up. As you compress a spring it does want to twist and does make a deep creaking sound as all 20 springs in the two trucks each twist a micro amount.

Bill, I highly appreciate your observations, its always good to have the RW point of view. But... :
I know how to model this effect, it can be done with 2 differential equations per rail car only, the only thing I need is someone to tell me what are springs' parameters - strenght, lenght, etc.. But any system will not start to move without external forces. Where are these forces comming from? One source can be found in rails' imperfection. But who will tell us where are these non-ideal places and soft rail connections? Should it be set randomly based on some kind of route-quality number? Second source can be found in side wind, what is pretty random thing, based on a weather and surroundings. Third source of forces is self sinusoidal movement of axles. Yes, this movement can be modelled as a simple sinus function with amplitude given by a speed. But what about sinusoidal movement dampers? How to model this impact? I have these questions because I'm an electrical engineer, I don't know this mechanical stuff deeply.
There is a lot of questions and "buts". The simpliest version is 3 additional equations per wagon, what is 150 equations for 50 wagon train - it scares me a bit. Finally, what amount of parameter settings will be left on players and people outside of ORTS? What more, a present train movement physics is a linear model only. We need to prepare 3-axes physics to model centrifugal forces and how to handle movements in a curve considering inertia without information about rail elevations in curves, derailment forces, etc.
If you know somebody who can help us with physics, please tell us. There are many testers and people with real world experience but we need more people with this experience who is capable to write down some equations, make some C# code and think about it in players' way.

Matej

[Lindsayts]

Matej Pacha, on 26 November 2011 - 03:41 AM, said:

Bill, I highly appreciate your observations, its always good to have the RW point of view. But... :
I know how to model this effect, it can be done with 2 differential equations per rail car only, the only thing I need is someone to tell me what are springs' parameters - strenght, lenght, etc.. But any system will not start to move without external forces. Where are these forces comming from? One source can be found in rails' imperfection. But who will tell us where are these non-ideal places and soft rail connections? Should it be set randomly based on some kind of route-quality number? Second source can be found in side wind, what is pretty random thing, based on a weather and surroundings. Third source of forces is self sinusoidal movement of axles. Yes, this movement can be modelled as a simple sinus function with amplitude given by a speed. But what about sinusoidal movement dampers? How to model this impact? I have these questions because I'm an electrical engineer, I don't know this mechanical stuff deeply.
There is a lot of questions and "buts". The simpliest version is 3 additional equations per wagon, what is 150 equations for 50 wagon train - it scares me a bit. Finally, what amount of parameter settings will be left on players and people outside of ORTS? What more, a present train movement physics is a linear model only. We need to prepare 3-axes physics to model centrifugal forces and how to handle movements in a curve considering inertia without information about rail elevations in curves, derailment forces, etc.
If you know somebody who can help us with physics, please tell us. There are many testers and people with real world experience but we need more people with this experience who is capable to write down some equations, make some C# code and think about it in players' way.

Matej

Hmmmmmmmmm, How many people would really apreciate this sort of accuracy in the mathematical modelling and to REALLY do a good job one would need to model the imperfections in the track and this would be beyond what would be reasonable to expect someone to do, the OR developers or route developers. Also how much impact is all this calculating going to have on a typical system, OR aleardy requirening a good fast system on a route that has both dense scenery and traffic, eg the SOB. The more mathematical modelling is put onto the system the slower it will end up performing. It being little good to have a very accurate simulator only capable of doing slower than 50 FPS. Much as I hate to say it the solution may be to put user controled random movements in the rolling stock to keep those that require it happy.

A point for all to keep in mind is the more difficult it will be to produce a route or rolling stock due to say accuarcy requirements for both the graphics and the "phsyics" the less number of people will be able/capable/willing to do the task. This is already to some extent a serious problem in the "physics" particularly power, traction and braking in MSTS rolling stock a signifcant proportion of the locos released being poor to very poor.

Lindsay