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Thread: ORTS Standard Engine Files

  1. #61
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    Quote Originally Posted by =FI=Ghost View Post
    This is what I have in my Table:

    GE ES44AC High Adhesion (GE GEVO-12; 4700 GHP)
    a. Starting tractive effort of 198,000 lbs (880.8 kN) up to 7.519 mph.
    b. Traction horsepower at wheel is 4,390 hp (3,276.12 kW); efficiency rating of 93.4%.
    c. Max Dynamic Brake effort of 117,000 lbs (520.442 kN) from 16.51 mph to 3 mph; linear fade from that speed to 0 lbs @ 1 mph.
    d. Dynamic Brake horsepower at wheel is 5,145.6 hp (3,840 kW).
    e. Increased weight of 195.954 metric tons (432,000.1884 lbs).
    f. Maximum speed of 75 mph.
    g. Fuel consumption @ notch 8 is 210 gallons per hour.

    Izvor:

    http://railworksamerica.com/forum/vi...p?f=30&t=12693
    We have essentially the same mass 432000lbs...so using the same Adhesion as the ES44AC ( indeed the AH may be higher, but not less ) we have a STE of 206064lbs...not 198000lbs.

    Looking over the railworks site you referenced I believe the difference lies in the adhesion values I am using vs. the ones on the railworks site.

    ES44AC for OR
    Mass 415130.4lbs, Adhesion=47.7% STE 198017lbs
    Railworks ES44AC physics
    Mass 416,008.02lbs, Adhesion=43.268% STE 17999835.00936 ( 180000lbs )
    We have agreement on the AC44AH mass - 432,000.1884 lbs - we just need to determine what adhesion to use.

    Finding the real value is something beyond my skill set and I suspect that of most people outside of an actual electrical/mechanical engineer employed by the builder...as the definition of Adhesion is:
    Adhesion = Coefficient of friction x Locomotive adhesion variable

    The friction coefficient between wheel and rail is usually in the range of .40 to .45 for relatively clean, dry rail in reasonable condition and is essentially the same for all locomotives. The locomotive adhesion variable represents the ability of the locomotive to convert the available friction into usable friction at the wheel rail interface. It varies dramatically from about .45 for old DC units to about .90 for modern AC units. This variable incorporates many factors including electrical design, control systems, truck type and wheel conditions.
    We can agree on the coefficient of friction as you see above, but knowing the Locomotive adhesion variable?? -- I have never seen that published...I don't think outside of the manufacturer that is considered useful knowledge. I've never found the actual forumla with the variables defined for finding the locomotive adhesion variable.

    After all that hot air.... What Adhesion do you think is reasonable for the ES44AH?
    Looking over everything...I'm wondering if an adhesion of 47.7% is high for the ES44AC, what do you think?
    Any other opinions...Bob, Derek are you guys around?
    Last edited by R. Steele; 05-16-2019 at 01:37 PM.
    Cheers, R. Steele [Gerry] It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.


  2. #62
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    These are the official specifications given in the ES44AC brochure by GE. It seems that the adhesion value of 43.268% gives a number closer to the one in the specs.

    ES44ACspecs.jpg
    Borislav
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  3. #63
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    Quote Originally Posted by =FI=Ghost View Post
    These are the official specifications given in the ES44AC brochure by GE. It seems that the adhesion value of 43.268% gives a number closer to the one in the specs.

    ES44ACspecs.jpg
    Borislav, thank you for the specs. I reworked everything, trying to account for inconsistencies and here is what I arrived at, look okay?
    Still, I'm left with a couple of questions...maybe someone who reads the thread will provide some insight.

    GE ES44AC and ES44AH Specifications

    1. ES44AC
    Mass: 415130.4lbs
    Adhesion: 43.268%
    STE: 179618.62lbs
    CTE: 145000lbs
    Gross HP: 4500
    Traction HP: 4365
    Max Speed: 75mph
    Max Dynamic Braking Effort: 98000lbs

    2. ES44AH
    Mass: 432000lbs
    Adhesion: 46.296%
    STE: 199998.72lbs
    CTE: 166000lbs
    Gross HP: 4500
    Traction HP: 4365
    Max Speed: 75mph
    Max Dynamic Braking Effort: 98000lbs

    These specs differ from the railworks ones in that:
    1. Dynamic braking effort is lower 98000lbs ( per mfg spec ) vs 117000lbs
    2. Gross HP is 4500 ( per mfg spec ) vs 4700HP (railworks)
    3. ...and the railworks braking HP is 5145.6 -- higher than the actual gross HP of the primer mover...is that actually possible?

    Regards, Gerry
    Cheers, R. Steele [Gerry] It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.


  4. #64
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    1. ES44AC
    Mass: 415130.4lbs
    Adhesion: 43.268%
    STE: 179618.62lbs
    CTE: 145000lbs
    Gross HP: 4500
    Traction HP: 4365
    Max Speed: 75mph
    Max Dynamic Braking Effort: 98000lbs

    From your post:-
    These are AC4400 figures.

    These are the ES44AC figures that I have

    ES44AC
    Mass: 420000lb
    Adhesion: ?
    STE: 198000lb
    CTE: 165000lb
    Gross HP: 4520
    Traction HP: 4390
    Max speed: 75mph
    Max Dynamic: 110000lb

    Both sets of figures above confirmed with BB's figures.
    Last edited by derekmorton; 05-16-2019 at 06:11 PM. Reason: extra information
    Cheers
    Derek

  5. #65
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    Adhesion should be a little higher in ES44AH models, due to their increased weight compared to standard ES44AC models (but I may be completely wrong on this one, as I am a psychologist, and not an engineer).

    With that in mind, 46.296% for AH models seems just right.

    The differences compared to those at the railworks site probably come due to different sources used for input data. While I was doing research for my Locomotive Specification Table, I often found different values for Mass/STE/CTE, or even HP/KW, for a certain model of locomotive. I even read how some real world train engineers testified that factory given specifications sometimes didn't match the specifications they came up with during testing and measurements.

    All in all, whenever I had official specification charts (like I did with Evolution Series locomotives), I used those. The most important thing for me was the standardization of my locomotive fleet, which was the reason behind creating the Locomotive Specification Table in the first place.
    Borislav
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  6. #66
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    Regarding the SD40-2 HP discrepancies in the Open Rails locomotive HUD

    I did some tests and found this...which confirms all other tests I've done.

    All testing done on my standard test route...Peter Newells Coals to New Castle Test Route.
    http://www.coalstonewcastle.com.au/physics/route/

    First Test: using the SD40-2 Std_eng file rated at 3140HP Gross, with ORTS Max Tractive Curves...same results are obtained...less than 3000HP, with load at 76.2%. Power to the rails is at 2397HP (I'm assuming this is power to the rails, because 2397HP divided by 3140HP = 0.76337 -- close enough) The SD40-2 has a locomotive eff. of 83% ....approx. 6% higher)

    1st Test=3140HP_Std_eng+MaxTractive Curves.jpg

    Second test: Increased Gross HP to 3925, enough to make a noticeable difference --- Now you will notice that power to the rail has remained approximately the same --2363HP ( the longer you run the test, it stabilizes at a slightly higher value) and the right side HP (rated Gross HP) shows 3925HP. The Load now reads 60.2%. ( 2362 divided by 3925 = 0.60203).
    Now this proves two things:
    1. Running power reading is coming from the MaximalPower line and probably also the DieselPowerTab of the ORTS DieselEngine Block
    (which was increased for this test from 3140HP to 3925HP)
    ...and
    2. Power to the rail did not increase -- The load percentage would have to decrease, which it did.

    2nd Test=OR_Std_Eng+3925HP+MaxTractive.jpg

    Third Test: Restored SD40-2 Std_Eng file Gross HP to 3140 and removed the ORTS Max Tractive Curve set. With this result.
    1. Running power restored to gross HP of 3140
    2. Load percentage up to 93.6% ( now 10% higher than SD40-2 locomotive efficiency of 83% )
    3. Power to the Rail is now at 2946 - almost 3000HP.
    3rd Test=No_Max_Tractive_Curves.jpg

    Conclusion. The advanced adhesion model does not correctly implement the ORTS Max Tractive Curve Set.

    Questions: Could my conclusion be wrong? Could I be constructing the curve set incorrectly? ..you betcha... Although the formula I'm using is recognized and used to find this type of traction effort. And the tractive curves do prove out when tested, they provide more reliable traction in the simulation. Although the power to the rails does not match what one would expect.
    There has been a suggestion to allow the ORTS curve sets when using the simple adhesion model.

    Any thoughts anyone? Any ideas? Light bulbs go on?
    Regards, Gerry
    Last edited by R. Steele; 05-16-2019 at 08:33 PM.
    Cheers, R. Steele [Gerry] It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.


  7. #67
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    The sd70 exhibits the same issue?

    I am running the simple adhesion model.
    Cheers
    Derek

  8. #68
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    Quote Originally Posted by derekmorton View Post
    The sd70 exhibits the same issue?

    I am running the simple adhesion model.
    Derek, my default is advanced adhesion. But you bring up an interesting point...so I'm going to make some test runs using the simple adhesion model.
    Cheers, R. Steele [Gerry] It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.


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