Adjusting SD40-2 dynos to make them more prototypical?
Started by xlspecial2617 posts7 min read
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I recently picked up the game now that I have a computer that can run it. After playing arond with it for about 20 minutes (Marias Pass. Closer to a rollercoaster than a real railroad) I went looking for better routes.Since I work for CP, (Not in Canada however) I was intrigued by the KHP route. After dl'ing the route I grabbed what I figured would be a "tough" run, the westbound sulfur train. Well, after bringing it down the hill without so much as breaking a sweat, I had the feeling the dynamics are a bit strong. (Or the train is awful light. Any input in how to compare what is in the sim to the prototype would be appreciated)For the era represented the dynos on CP SD40-2's should only be 45,000 lbs. Not the standard 60,000 lbs. Only recently were these units adjusted to 60,000. The reason for the lower rating was the fact that CP ran these units in sets of 5 units through the mountains. 300,000 lbs of total retardation on the head end, or middle for that matter, is only asking for derailments due to excess buff force.What I'm asking is this; Where do I find the values for the dynos and what measure does the game use? Is it something in thousands of pounds or some other measure?Thanks, Todd Jones Engineer Canuck Pacific Railway
RE: Adjusting SD40-2 dynos to make them more prototypic, shoskins, Nov-10-02, 09:06 AM, (1) RE: Adjusting SD40-2 dynos to make them more prototypic, plainsman, Nov-10-02, 09:33 AM, (2) RE: Adjusting SD40-2 dynos to make them more prototypic, fwbryan, Nov-10-02, 11:42 AM, (3) RE: Adjusting SD40-2 dynos to make them more prototypic, plainsman, Nov-10-02, 02:51 PM, (4) RE: Adjusting SD40-2 dynos to make them more prototypic, xlspecial261, Nov-10-02, 04:45 PM, (5) RE: Adjusting SD40-2 dynos to make them more prototypic, fwbryan, Nov-11-02, 11:20 AM, (6)
RE: Adjusting SD40-2 dynos to make them more prototypic
Look in the http://www.train-sim.com File Library, there IS a file available for updated dynamic brake physics. It boils down to just changing a couple of the values within the settings.
RE: Adjusting SD40-2 dynos to make them more prototypic
Hi Todd, I responded to your post in another thread, but I would be happy to work with you to get the performance you want as much as possible. Feel free to leave a way to contact you, and i will provide some files and suggestions to help. Thanks, Bob Boudoin V4.1 physics upgrades
RE: Adjusting SD40-2 dynos to make them more prototypic
Bob and Todd and whoever else is interested in realistic operation: I would like to work with you on updating locomotive physics. I have done some tweaking of my own and feel that my locomotives respond more accurately now. I have also changed the power output for throttle notches to 4-11-23-34-50-61-85-100% (1 thru 8), based on actual Dash-9 specs IIRC, which requires both eng and cvf changes. You have more flexibility on the low (switching) end.Here's a sample of part of my eng file for a CP SD-40. Some of this is based on fact and some on feel and some is unchanged, but brakes will apply and release more slowly.AirBrakesAirCompressorPowerRating( 3.1 ) AirBrakesMainMinResAirPressure( 14.7 ) AirBrakesMainMaxAirPressure( 140 ) AirBrakesMainResVolume( 9 ) AirBrakesAirCompressorWattage( 19000 ) AirBrakesCompressorRestartPressure( 126 ) AirBrakesAirUsedPerPoundsOfBrakePipePressure( 2 ) AirBrakesIsCompressorElectricOrMechanical( 1 ) EngineBrakesControllerMinPressureReduction( 6 ) TrainBrakesControllerMinPressureReduction( 6 ) EngineBrakesControllerHasProportionalBrake( 1 ) EngineBrakesProportionalBrakeLag( 0.45 ) EngineBrakesControllerMaxApplicationRate( 2.667 ) TrainBrakesControllerMaxApplicationRate( 1.2 ) EngineBrakesControllerMaxReleaseRate( 20 ) TrainBrakesControllerMaxReleaseRate( 1.2 ) EngineBrakesControllerEmergencyApplicationRate( 7.7 ) TrainBrakesControllerEmergencyApplicationRate( 7.7 ) EngineBrakesControllerMinSystemPressure( 0 ) TrainBrakesControllerMinSystemPressure( 0 ) EngineBrakesControllerMaxSystemPressure( 72 ) TrainBrakesControllerMaxSystemPressure( 90 ) EngineBrakesControllerEmergencyBrakeTimePenalty( 60 ) TrainBrakesControllerEmergencyBrakeTimePenalty( 60 ) EngineBrakesControllerFullServicePressureDrop( 26 ) TrainBrakesControllerFullServicePressureDrop( 26 ) DynamicBrakesMinUsableSpeed( 8 ) DynamicBrakesMaximumEffectiveSpeed( 25 ) DynamicBrakesMaximumForce( 260kN ) < - will change CP to 195 DynamicBrakesResistorCurrentLimit ( 750 ) DynamicBrakesCutInSpeed( 5 ) DynamicBrakesMaxAirBrakePressure ( 70 ) DynamicBrakesFadingSpeed( 7 ) DynamicBrakesDelayTimeBeforeEngaging ( 20 )< - makes it 10 sec DynamicBrakesMaximumSpeedForFadeOut ( 60 ) DynamicBrakesEffectAtMaximumFadeOut( 0.5 ) DynamicBrakesHigherSpeedCurveExponent( 1 ) DynamicBrakesLowerSpeedCurveExponent( 1 ) DynamicBrakesNumberOfControllerNotches( 10 ) DynamicBrakeHasAutoBailOff ( 1 )Please copy me into any e-mail on this subject not posted on the board.Frank W. Bryan fwbryan@fidnet.com
RE: Adjusting SD40-2 dynos to make them more prototypic
Hi Frank, A few points to note. With dynamic braking, your setup will introduce some major problems due to a bug in the sim engine. Inorder to avoid this, you set the line "DynamicBrakesMaximumSpeedForFadeOut ( xxx ) to a speed much higher than will ever be reached, usually 250-500 mph. You then set the line "DynamicBrakesEffectAtMaximumFadeOut( x.x )" to 0. The reason, is that otherwise the dynamic force drops from 50% of max at 60 mph to 0 at 60.1 mph, which is not what really happens. Next, Peter Baker and I did a lot of curve matching, and the exponent values in Peter's work will yield a more realistic dynamic profile. Next, you will want to take out the notches for dynamic application, as this is a smooth, not notched setting. Also, the "DynamicBrakesMinUsableSpeed( X )" value will depend whether there are extended range or regular dynamic brakes. Peter and I did both. In the first braking section you display, the value "AirBrakesAirUsedPerPoundsOfBrakePipePressure( 2 )" will result in too rapid a blowdown, I feel 1.3-1.6 is more realistic. In the middle section, I use some differnet settings, (you are using Wurger's settings mostly), but I won't argue with either setup, both are much better than KUJU's. There is also another section near the top of the file which needs to be set as well. MaxBrakeForce ( 71.3kN )
EmergencyBrakeResMaxPressure( 110 ) TripleValveRatio( 2.5 ) MaxReleaseRate( 7 ) MaxApplicationRate( 5.5 ) MaxAuxilaryChargingRate( 1.8 ) EmergencyResCapacity( 10 ) EmergencyResChargingRate( 2 ) BrakeCylinderPressureForMaxBrakeBrakeForce( 64 )For a 90 pound line, the value is 64, for the compromise 95 pound line I use (some roads run 100, most run 90), it is 66. It would be 57 in an older 80 pound system. Hope this helps, Bob
RE: Adjusting SD40-2 dynos to make them more prototypic
Thanks guys. This is the type of info I am looking for.I'll try some of these out and let you know what I think.Also, since extended range dynos were brought up, I should note that CP SD's do not have extended.Thanks again, Todd Jones
RE: Adjusting SD40-2 dynos to make them more prototypic
Bob,Thanks for the info. On the subject of dynamic brakes, my 60 mph Fade Out speed explains why once when cruising downhill at 60 in dynamics the ammeter kept bouncing from 0 to whatever.I have a book "Management of Train Operation and Train Handling" published in the 80's by the Air Brake Association, and it has some interesting data, which you may or may not have in some form. For dynamic brakes there is a table of retarding force for a 6-motored 3300HP dynamic brake (3000HP diesel?) with extended range braking:Speed Lbs 6 60000 (14,400 for standard dynamic) 12 60000 (30,000 for standard dynamic) 24 60000 (remander same for standard) 30 48600 40 34000 50 28800 60 24000 70 204004 axle units are 2/3's the above valuesAlso shown is a graph of a GE braking effort vs. speed which shows the effort at each notch position. Reading the graph, the effort for notches 1 through 8 at max effort speed (8-24 mph) are approximately 5000, 9500, 12500, 17500, 22000, 33000, 40000 and 60000. Note that there is no standard increment. I had also thought that the older second generation units (SD40) had notched dynamic brakes, although newer units do not.Air brakes are complex enough as they are without trying to figure out MSTS's mis-interpretation of them. I just try to tweak them to get a better feel. I compared the time it takes to release an application (defined as MR back to 140) with the Trainmaster sim and they tracked pretty well after my tweaking. I'm interested in anyone else's tweaks. One interesting figure from the book mentioned above: Approximately 20 cu ft of free air must be supplied to each car to charge it to 80 psi. And it takes (reading graph) 6 seconds to *initiate* brake cylinder pressure on the last car of a 50 car train (80 psi pipe), 13 seconds for 100 cars, 16 seconds for 150 cars. A 50 car train will have full brake cylinder pressure in all cars in about 90 seconds, (first car gets it in 30 seconds), 150 cars in 3 minutes (but 80% of it after about 90 seconds).I assume the brake values in the front part of the eng file (before lights) refers to the independent brake only. I had already included some of the other changes you mentioned.Frank
