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Thoughts On Csx Physics

Discussion in 'General Discussion' started by Anthony Pecoraro, May 23, 2019.

  1. SaMa1

    SaMa1 Member

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    I am delighted of the interest from the developer. Here is the original excel in zip for scrutiny. The original measurements were done in metric and converted into imperial units but all the conversions are there in the file. The measurements in TSW show curvilinear behaviour as in your figure, however, there is something in your simugraph implementation that multiplies the resulting acceleration.
     

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  2. TrainSim-Matt

    TrainSim-Matt Staff Member

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    Passed it on to our lead engineer and he has some ideas he wants to explore next week. Very helpful, thanks!
     
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  3. dan.marcusior73

    dan.marcusior73 Member

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    Agreed. I too think this is what's happening. Or...maybe the weight is off? Something is.
     
  4. dan.marcusior73

    dan.marcusior73 Member

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    You know, I wonder if part of the rapid acceleration following transition is slack action running out. In real life, each SD40-2 is designed to transition at a slightly different speed (some at 23.5mph, some at 24, some at 24.5, etc) so a consist of locos wont transition at the same time. If this happened in real life, you'd get what you have in the sim - sudden drop of tractive effort, the slack would run in, and then all of the sudden a build up to 900 amps (or whatever it is) and a good abrupt yank, sudden head-end acceleration, and bang as the train is pulled taught again! It would break couplers for sure. I think they all transition at the same time in the sim which is wrong. This *CAN* happen in real life, and if you notice it, you're supposed to lower the throttle before making transition to limit the rough handling. We can simulate that in the sim.

    SD40-2's make upward transition at 24mph (give or take 1 mph) and downward at 18mph. Also, if you're below 24 mph and you drop the throttle to notch 1, it will do a downward transition to series. If then you notch back up past notch 5, and still around 24 mph, it will go back to parallel.

    The locomotives are supposed to restore power to the traction motors gradually after transition. The ones in the sim do it abruptly (which COULD happen in real life if the loco is operating out of spec). EDIT: Actually, it is pretty slow and smooth. I take that back.
     
    Last edited: Jun 3, 2019
  5. StratPlayer62

    StratPlayer62 Well-Known Member

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    Matt, just want you to know how happy I am that you are on top of this. Nobody here is expecting perfection, we know it is a work in progress, and many of us here are happy to help work out these problems, but we need the staff to communicate with us, and having you communicating on the forums here recently has been a really positive experience!
     
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  6. nne4229

    nne4229 Well-Known Member

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    Agreed^
     
  7. Michael Newbury

    Michael Newbury Well-Known Member

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    Yes I also agree
     
  8. Pensfanvw

    Pensfanvw Member

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    Well spoken StratPlayer62. Agree.
     
  9. jörgen Näslund

    jörgen Näslund Active Member

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    Okay Matt say
    The wagon weight issue is on the big list of things to do. So very good.

    But something i think is strange is wind resistance. Stack train in 50-60 mph should go much heavier i think.
    Many (or all) trains here rolling very easy even in higher speed. I know they are short (max 40 wagons in Sim)
    But i think they should go much heavier in 50-60 mph. Many times i can just roll and have run 1-3 to maintain speed.
    In open rails and Run8 trains go much heavier. And in youtube videos almost the engine goes in run8 to get higher speed.

    Do you agree with me in this issue. I think Matt should take this wind resistance in big list for wagon to do. (Many things in this big list)
     
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  10. Dakota

    Dakota Member

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    I'm delighted to see this discussion. I hope the devs will focus on TSW as a train driving simulator and not let some peoples' desire for extreme beauty and perfect scenery matching to override the basic reason for this ... "a train driving simulator".
     
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  11. kalteVollmilch

    kalteVollmilch Well-Known Member

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    I really would like to see this list at some point.
    Considering the amount of times Matt answered with 'it's on the long list', it's got to be a couple of meters long.
    Also I would be interested in getting to know why it takes an eternity to resolve one thing of this list, while 5 other things get added at the same time
     
  12. Shukal

    Shukal Well-Known Member

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    Considering that spearate teams are responsible for route building and rolling stock, why would one affect the other? No one seems to be happy about half-assed routes like NEC either.
     
  13. ARuscoe

    ARuscoe Well-Known Member

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    He's a project manager of an evolving piece of software. It's probably longer than we think because you're limited by the things you know they're working on whereas they are not limited by that

    On this one, I know from my own developments that some things that are seemingly simple can have huge effects down the line so your "one thing" might not just be that
    Also, depending on what that "one thing" is, it might be on a system that isn't being looked at right now and given the way they've developed the routes and locos has changed in the last year (Matt said as much on one of the devstreams) it could take much longer to change something small, but fundamental, on one of the original routes whereas something seemingly larger but on a newer route might be easier simply because they don't have to relearn how they did things "back then"
     
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  14. mokady

    mokady Member

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    After some simple calculations it looks like well cars with 2 40 feet containers weights about 20 tons each which is exact wieght of empty husky well car from Greenbrier. 50 cars = 1000 tons so it is very very light train and quite overpowered for 2 engines.
     
  15. jörgen Näslund

    jörgen Näslund Active Member

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    Test Gravity
    Test train uphill (from Cumberland to Hyneman) 1,3% uphill. (test Gravity and engine force etc.)

    08:44 Q130 Autorack Q217 to Philadelphia to Connelsville (2 ac4400 50 AutoRack Wagons "Empty or loaded")
    We know TSW have "wagon weight issue bug" which always makes them empty of cargo But we don't know the base weight for each wagon.
    (Dovetail maybe have change it to higher weight to compensate for the bug)


    Run8 2 SD70Mac 50 Empty AutoRack wagons 2500 ton train. Ash Hill (used 1,5% track not 2,2)

    1 Test Let the train to just rolling from 25 mph to 0 Mph in 1,5 % uphill. (Test Gravity formulas)
    Run 8= 46 seconds the train is stopping
    TSW= 70 seconds the train is stopping (should be shorter due to all the curves Curve resistance)
    It is 52% more in TSW

    2: Speed with this 2 trains in in 1,5 % uphill (max force from Locomotive)
    Run 8= 28 mph Here i know the train weight is 2500 ton
    TSW= 26 mph Not knowing the real train weight here 2500- 4500 ton

    Hard to draw conclusions when you do not know the weight of the train in TSW. It is empty it is right, but why the train rolls 52% longer than run8

    When i driving TSW in flat and uphills i get a wrong feeling. Yeah the train lose speed when it goes up, but not so much I expect.
    Both Run8 and Open rails have this right feeling.
    Is really Gravity formulas relation to slopes right in TSW?.
    Maximum kinetic energy when trains have 25 mph . When they start rising, the kinetic energy begins to be converted to gravitational potential energy. The sum of kinetic and potential energy in the system remains constant, ignoring losses to friction. and wind resistance. Then the train have stopped the kinetic energy is 0 and potential energy is max

     
    Last edited: Jul 19, 2019
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  16. Coppo

    Coppo Active Member

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    It is not quite that simple.
    Kinetic energy is associated with movement. If a vehicle is moving it has KE. If it is stationary it does not.
    Potential Energy relates to an object's position. So if the train is going uphill at a constant 25 mph then the KE remains constant and the PE increases. Once the train stops it just has PE, and the KE is zero. This PE can turn into KE if the train rolls downhill (and can have devastating consequences, as many records show). But that may not equal the KE of the trian going uphill (it might be travelling faster)...
    It gets more complicated when you start thinking about it. Different parts of the train at different heights, etc. And,as you say, that excludes the various resistances...
    If I recall my physics classes correctly, the maths involved can become quite significant the more variables you take into account... :)

    There is more that TSW could, and should, do to increase realism, but there has to be a compromise somewhere because of the amount of maths processing involved coupled with the need to keep it entertaining...
     
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  17. jörgen Näslund

    jörgen Näslund Active Member

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    Is the Cargo weight issue fixed in trains in Peninsula corridor? It seems so
    Tested scenarios Rocky road with wagons loaded with aggregates. 2 gp38 and with 6 hopper wagons
    Uphill 0,1 percent i can hold I could keep a speed of 9.6 km/h. with run1 in engine
    When i have unloaded the same train i can hold a speed 14 km/h and over.
     
    Last edited: Aug 22, 2019
  18. DominusEdwardius

    DominusEdwardius Member

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    It is fixed on Peninsula Corridor, but only that one at the moment.
     
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  19. StratPlayer62

    StratPlayer62 Well-Known Member

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    Really nice to hear that something is working properly from the start, I just hope they make the fix on older routes.
     
  20. jörgen Näslund

    jörgen Näslund Active Member

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    Yes I drive loaded coal train CSX Heavy Haul. It feels so incredibly light.
    I really hope they fix this in CSX Heavy haul soon. But we know now they can fix it.
     
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