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jtr1962 (95 posts)
Apr-06-02, 07:20 AM (EST) "Interesting findings regarding the Adheasion parameter" I did some experimenting with the Adheasion parameter, and found some interesting results. First of all, the fourth value is not used at all, as mentioned in the tech docs. The third value is adhesion while sanding, according to the tech docs, but this is only partially true. It also turns out to be a multiplier for the first two values, which are adhesion under slipping and normal conditions, respectively. All three values can be altered simultaneously by changing the NumWheels parameter, which is really just a divider. The actual divisor used by the sim is NumWheels/2, so setting NumWheels equal to 2 means that the actual values in the Adheasion parameter are used by the sim.For the purposes of the experiment I used the HHP locomotive with the MaxPower, MaxForce and MaxContinuousForce values set very high so that the tractive effort would be limited by the Adheasion parameter and NumWheels only. I also set NumWheels equal to 2 to effectively remove it's influence. When the third value of the Adheasion parameter is equal to 2(the default value), the maximum tractive effort equals the second value times the locomotive weight. The slipping tractive effort equals the first value times the locomotive weight. However, the tractive effort while sanding is 0.95 times the locomotive weight, which is clearly wrong. Unfortunately, reducing the third value also reduces the first two values by a proportional amount, so the third value is also effectively a multiplier for the first two values, and the value of the multiplier is equal to one-half of the third value. The net results of what I discovered are as follows:Tractive Effort(slipping) = {(first value)*(third value/2)*(locomotive weight)}/(NumWheels/2) = (first value)*(third value)*(locomotive weight)/(NumWheels)Tractive Effort(normal) = {(second value)*(third value/2)*(locomotive weight)}/(NumWheels/2) = (second value)*(third value)*(locomotive weight)/(NumWheels)Tractive Effort(sanding) = 0.95*(third value/2)*(locomotive weight)}/(NumWheels/2) = 0.95*(third value)*(locomotive weight)/(NumWheels)I also discovered that these same values are used while braking, but for the locomotives only. NumWheels and Adheasion have no effect whatsoever on the braking of wagons. The only ways to control the braking of wagons are to adjust the MaxBrakeForce and BrakeCylinderPressureForMaxBrakeBrakeForce parameters.The sim uses multipliers to account for reduced adhesion under rain and snow conditions(the values are 0.9 and 0.55, respectively, and can be adjusted in the default.wag file). These multipliers affect the tractive effort(and braking for locomotives) under slipping and normals conditions only. The tractive effort while sanding remains the same even in bad weather, and interestingly, you can also increase the maximum brake force exerted by the locomotive by sanding while braking. Once again, there is no change whatsoever in the braking behavior of wagons under bad weather conditions. This is dependent only upon the MaxBrakeForce and BrakeCylinderPressureForMaxBrakeBrakeForce parameters, and remains the same in all types of weather.The practical results of all this is that you can set both normal and sanding adhesion to reasonable values since the sim uses the NumWheels divider for all three Adheasion values. In the case of the HHP, I used Adheasion ( 0.35 0.8 2 0 ) and NumWheels( 5 ). According to my equations above:Tractive Effort(slipping) = 0.35*2*(locomotive weight)/5 = 0.14*(locomotive weight)Tractive Effort(normal) = 0.8*2*(locomotive weight)/5 = 0.32*(locomotive weight)Tractive Effort(sanding) = 0.95*2*(locomotive weight)/5 = 0.38*(locomotive weight)These all seem to be reasonable values for a locomotive equipped with an electronic antislip system. For a regular diesel locomotive without an antislip system I might use Adheasion ( 0.56 0.8 2 0 ) and NumWheels( 8 ), to give sliding, normal, and sanding coefficients of 0.14, 0.20, and 0.24, respectively. I'm not 100% sure what the sliding coefficient should be, but I think values between 0.1 and 0.15 are realistic for normal conditions. For a steam locomotive you can use the same value for Adheasion(to give the same ratios of sliding, normal, and sanding adhesion), but simply adjust the NumWheels parameter up to account for the reduced percentage of the weight on the drivers. The same can be done for diesel locomotives with a A-1-A A-1-A wheel arrangement(three axle trucks with the middle wheel unpowered). In that case, you would use NumWheels( 12 ) and the adhesion values would all be reduced by one-third which would be realistic since only two-thirds of the locomotive weight is on the driving axles. In all cases you must set the either the MaxForce or MaxContinuousForce parameter(or both) to be at least equal to the tractive effort while sanding, provided this is realistic for the particular locomotive, in order to have the tractive effort limited by the Adheasion and NumWheels parameter. If you set MaxForce and MaxContinuousForce to something smaller, then your maximum tractive effort will be limited to whatever those parameters are set for(at least under normal conditions). The Adheasion and NumWheels parameters might still limit your tractive effort further under rain and especially snow conditions.Please note that MaxForce is a value for maximum tractive effort that just seems to be used by the locomotive between about 13 and 26 mph in place of MaxContinuousForce, and at no other time. It can be more, less, or equal to MaxContinuousForce, so you can use it to further modify the tractive effort curve. For example, some EMUs experience a roll-off in tractive effort at 15 or 20 mph and then an increase a few mph later as the motors go from a series to a parallel arrangement(even some electronically controlled EMUs exhibit this behavior), so making MaxForce less than MaxContinuousForce can simulate this.There is also an interesting side effect of the MaxContinuousForce parameter on the tractive effort curves of electric locomotives only. By setting it higher(effectively reducing the speed at which the locomotive develops its maximum tractive effort), you end up with more horspower at high speeds even without changing the MaxPower parameter. For example, the graph below shows different amounts of tractive effort when only the MaxContinuousForce parameter is varied, and MaxPower is kept constant at 6000kW: I'm still trying to figure out the exact relationship here, but this is yet another way to fine tune the tractive effort curve of electrics, yet still have the maximum tractive effort limited to realistic values by using the Adheasion and NumWheels parameters. Unlike diesels, the horsepower of electrics varies(sometimes widely) over the entire tractive effort curve, so the horspower of an electric must be specified in a number of ways-absolute maximum peak power(usually at a given speed), maximum continuous power(also at a given speed), power at maximum rated speed(might be less than maximum continuous power), and zero power speed(usually at 5-10 mph above the maximum rated speed, the point where the locomotive tractive effort curve falls off sharply and equals the locomotive resistance at that speed). For example, an AEM-7(prior to the rebuild), was rated at 5600 HP continuous @ 125 mph, and 7000 HP peak(not sure of the speed, but I believe it was at 60 mph). I'm not sure how much the AEM-7's could exceed 125 mph by, but the power curve fell off sharply above that point. Nevertheless, I did time a couple of AEM-7s hauling 5 or 6 Amfleets through Princeton Junction at over 130 mph(I used a stopwatch to time how long the 85-foot coaches would take to pass a fixed point). Alert Edit | Reply | Reply With Quote | Top
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Subject Author Message Date ID RE: Interesting findings regarding ... plainsman Apr-06-02 1 RE: Interesting findings regarding ... jtr1962 Apr-06-02 2 RE: Interesting findings regarding ... plainsman Apr-06-02 3 RE: Interesting findings regarding ... b101uk Apr-06-02 4 RE: Interesting findings regarding ... plainsman Apr-06-02 5 RE: Interesting findings regarding ... b101uk Apr-07-02 6 RE: Interesting findings regarding ... plainsman Apr-07-02 7 RE: Interesting findings regarding ... mBusolt Apr-09-02 8 RE: Interesting findings regarding ... jtr1962 Apr-09-02 9 RE: Interesting findings regarding ... b101uk Apr-09-02 10 RE: Interesting findings regarding ... plainsman Apr-10-02 11 RE: Interesting findings regarding ... b101uk Apr-11-02 12 RE: Interesting findings regarding ... jtr1962 Apr-11-02 13 RE: Interesting findings regarding ... b101uk Apr-11-02 14 RE: Interesting findings regarding ... mBusolt Apr-12-02 15 RE: Interesting findings regarding ... Jeff Apr-12-02 16 RE: Interesting findings regarding ... jtr1962 Apr-13-02 17 RE: Interesting findings regarding ... b101uk Apr-13-02 18 RE: Interesting findings regarding ... jtr1962 Apr-14-02 20 RE: Interesting findings regarding ... SP9800 Apr-14-02 19 RE: Interesting findings regarding ... jtr1962 Apr-14-02 21

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plainsman (835 posts)
Apr-06-02, 03:08 PM (EST) 1. "RE: Interesting findings regarding the Adheasion parameter" This is quite interesting. If you take 4 locomotives:
GP7,GP40(predash2),GP60,andAC6000CW, it looks like this would yield the best numbers
GP7-0.18,0.37,1.8,Numwheels4 gives 0081,0.1665,0.4275
GP40-0.23,0.47,1.8,Numwheels4 gives 0.1035,0.2115,0.4275
GP60-0.29,0.60,1.8,Numwheels4 gives 0.1305,0.2700,0.4275
AC60-0.37,0.64,1.8,Numwheels3.2 gives 0.2081,0.36,0.5344
Have you figured out how the antislip switch functions mathmatically? That would be very interesting to know.
Thanks,
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
jtr1962 (95 posts)
Apr-06-02, 03:29 PM (EST) 2. "RE: Interesting findings regarding the Adheasion parameter" As best as I can tell, the antislip switch just keeps the adhesion at the maximum "normal" value all the time. In the case of my HHP-8, that means I get 38% adhesion while sanding regardless of weather, 32% in clear weather, 28.8%(=0.9x32%) in the rain, and 17.6%(=0.55x32%) in the snow. The sliding friction value of 14% doesn't really seem to be used at all, even while braking.Just as a side note, Bob, non-integer values for NumWheels either round or chop to the nearest integer, so that NumWheels(3.2) would give the same result as NumWheels(3). I found this out while trying to fine tune my adhesion values. With my method, I generally try to keep the third value in the Adheasion parameter at 2 all the time(so I don't have to deal with a multiplier for the first two values), and then adjust NumWheels accordingly to get the desired result for sanding adhesion. After that, I can play with the first two values to get appropriate sliding and normal adhesion values.
BTW, Bob, are those sanding values you used really that high? I wasn't aware that you could get in excess of 42% sanding adhesion, and over 53% with a modern antislip system. If so, I'll adjust my values upward for the HHP-8. I did hear that the newest freight locomotives develop about 38% to 40% adhesion, but I assumed that was with sand. Remove | Alert Edit | Reply | Reply With Quote | Top
plainsman (835 posts)
Apr-06-02, 03:43 PM (EST) 3. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-06-02 AT 03:56 PM (EST)
On the AC locomotives, the best performance I am aware of is an observed 188,100 MTE from a 427,000 pound AC6000CW which yields 44.05%. An SD90Mac is almost as good at just over 43.5% from the tests I am aware of.
It seems that the 1.8 works better if you can't adjust the sanding root value. Using 3 for AC traction numwheels would be a lttle too effective for sanding, but would be right on the 38% which EMD uses as a field objective in good conditions on good rail. It might be necessary to use 1.6 to get the sanding results down to reason on the DC locomotives, and up the first values a little. The tests Peter Baker and I ran showed a value between 1.55 and 1.8 worked best for the third parameter on most equipment we checked.
The other interesting thing is that it appears the ice vs wet rail spread is too great. At the tremendous pressure of contact, most ice behaves more like wet rail than actual ice.
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
b101uk (57 posts)
Apr-06-02, 06:23 PM (EST) 4. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-06-02 AT 06:24 PM (EST)hi
during my test(modern disel,eletric) i found it pointless to change the number of wheels to any thing other than 1. as all you do is work out the second Adheasion value to 5 desimal places. this then leavs one simple calulation provided you have set the Mass,MaxPower, MaxForce,MaxContinuousForce corectly.a quick way to find the right seting for the 2nd Adheasion value is to find the min ALL WETHER (snow) MSTE of from loco makers or other site , convert to % of Adheasion
devide that % by /100 then -0.02 from that then place that number in the second Adheasion value.
eg 35% /100= 0.35 - 0.02 = 0.32 =second Adheasion value a simple and efectiv way to get it within <0.003 .on my sd90ac i calculated the second Adheasion value to be
"0.31831" (35% Adheasion or 148750lbF MSTE repoted in game in snow no sanding, with AntiSlip, 425000lb, 192.831T loco useing "MaxPower ( 6000HP )"MaxForce ( 200000LBF )"MaxContinuousForce ( 170000LBF )"DieselEngineSpeedOfMaxTractiveEffort( 11.2mph )".i beleve all MSTE & CTE specs given for a loco are without the ade of sanding and that with sanding on thay will gane most if not all there MSTE & CTE back as a AntiSlip system will never alow higher than MSTE & CTE even with a surpless of Adheasion.re observed TE in locos (real life) when looking for info on sd90 types i found driver & other dater on wot sd90 could do in real life, some of the things i found were.
1 sd9043mac,sd90mac & sd90ac will deliver 55% of ther HP,CTE,MSTE with eather #1 or#2 inverter not working ie only powering one bogie.
2 thay deliver there full stated DBF down to <0.5mph
3 sd90mac,sd90ac will pull upwards of 195000lb TE in dinamic creep mode (<12mph) good rail condishons.b101uk Remove | Alert Edit | Reply | Reply With Quote | Top
plainsman (835 posts)
Apr-06-02, 07:41 PM (EST) 5. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-06-02 AT 07:53 PM (EST)
The independant test data I have seen suggests the 195,000 pound pull is unrealistic. The best I have heard about oin an SD90Mac is just over 185,000 pounds from a 425,000 lb. locomotive.
The problem with your method is it leaves the sanding traction way too high. Depending on how you set sanding speed this could result in much too much pull at speeds above the minimum continuous speed (take a look at a TE curve).
A fresh AC6000CW or SD90Mac should be able to do a little better than your value on good rail under normal conditions. Your starting point should be more like 38%.
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
b101uk (57 posts)
Apr-07-02, 10:26 AM (EST) 6. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-07-02 AT 10:47 AM (EST)hi
RE:"The problem with your method is it leaves the sanding traction way too high. Depending on how you set sanding speed this could result in much too much pull at speeds above the minimum continuous speed (take a look at a TE curve)."if you were going to bother working out the Adheasion values then i think you would set a max speed and time for sanding? also the game WILL NOT let the the sanding MSTE,CTE for any given speed to be higher than the dry rail value of Adheasion(MaxForce, MaxContinuousForce), i sujest if you have a big margin bitween your reported dry rail MSTE,CTE and sanding MSTE,CTE then it is becouse you
have to low an amout of Adheasion in the 1st place! by useing NumWheels values grater than "1"(for each increment of 1 you lose 50% of your MSTE,CTE,HP to rail).
for each 0.1 change in the 3rd Adheasion value you lose 0.05% of your MSTE,CTE,HP to rail.
BUT if you switch sanding ON your MSTE,CTE,HP to rail will go up to the stated values in the MaxPower, MaxForce, MaxContinuousForce parts of the .eng file.
RE:"A fresh AC6000CW or SD90Mac should be able to do a little better than your value on good rail under normal conditions. Your starting point should be more like 38%."the second Adheasion value is NOT the for "normal conditions"
its for the min % of Adheasion the loco has eg in the snow in the game BUT if you ajust it down to apx<0.22 +-0.03 you will not get the corect amout of MSTE,CTE or HP to the rail (becouse of LOCO MASS).
EG the dash9 with a seting of <0.215 yoy will get 100% of the MSTE,CTE and HP to the rail but you will not get any ware near the corect amount of MSTE,CTE,HP to the rail in snow and rain due to the fact the 2nd Adheasion value is DIRECTLY linked to the LOCO MASS in the .eng file.
eg useing a defualt dash9 but with JUST the second Adheasion value changed (MSTE)value 0.38 dry=146271LB, rain=146271LB, snow=142740LB. snow with sanding=146271LB.
value 0.35 dry=146271LB, rain=146271LB, snow=131471LB. snow with sanding=146271LB.
value 0.3 dry=146271LB, rain=146271LB, snow=112690LB. snow with sanding=146271LB.
value 0.25 dry=146271LB, rain=146271LB, snow=93908LB. snow with sanding=146271LB.
value 0.215* dry=146271LB, rain=132154LB, snow=80761LB, snow with sanding=146271LB.
value 0.2 dry=136593LB, rain=122934LB, snow=75126LB. snow with sanding=146271LB.
* a value of 0.214 is the point ware the dry rail MSTE,CTE,hp is afected due to the MASS of the dash9as above with a defualt dash9 other its MASS has been changed to 165T (defualt=155t)value 0.38 dry=146271LB, rain=146271LB, snow=146271LB. snow with sanding=146271LB.
value 0.35 dry=146271LB, rain=146271LB, snow=139953LB. snow with sanding=146271LB.
value 0.3 dry=146271LB, rain=146271LB, snow=119960LB. snow with sanding=146271LB.
value 0.25 dry=146271LB, rain=146271LB, snow=99966LB. snow with sanding=146271LB.
value 0.215* dry=146271LB, rain=140680LB, snow=85971LB. snow with sanding=146271LB.
value 0.2 dry=145406LB, rain=130865LB, snow=79973LB. snow with sanding=146271LB.changeing the 2nd Adheasion value of the gp38 has no efect becouse of the way the .eng file is set out!.most people fall foul of the simple system enployed becouse thay use US tones or thay fail to use the corect convershon rate or do not calculate it to the corect amout of desimal places. b101uk
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plainsman (835 posts)
Apr-07-02, 02:07 PM (EST) 7. "RE: Interesting findings regarding the Adheasion parameter" Hi,
I think you may be taking the default weight too seriously. I don't know any railroad that runs a C44-9W with less than 400,000 pounds and most are 410,000 pounds. This is almost 186 metric tons. I have no idea where the sim came up with the 155 metric ton weight, but I don't use it!!!! Now if you use the correct weight, the adhesion at which the dry rail is modified is over 35% and the real world adhesion limit is actually less than that, more like 31-32%.
Now an AC600CW has actually measured an observed 188,100 pound pull from a 427,000 pound locomotive. That is over 44% adhesion.
Another point to mention, unless you also change the third parameter in the adhesion line to 1, putting numwheels at 1 will result in everything being multiplied by the value you use in that parameter. Now as you are aware, as the speed increases, the TE drops and having the MTE value being the limiting factor will no longer work, as your TE at speeds above CTE will be excessive.
Bob Remove | Alert Edit | Reply | Reply With Quote | Top
mBusolt (5 posts)
Apr-09-02, 10:37 AM (EST) 8. "RE: Interesting findings regarding the Adheasion parameter" >Another point to mention, unless you
>also change the third parameter
>in the adhesion line to
>1, putting numwheels at 1
>will result in everything being
>multiplied by the value you
>use in that parameter. Now
>as you are aware, as
>the speed increases, the TE
>drops and having the MTE
>value being the limiting factor
>will no longer work, as
>your TE at speeds above
>CTE will be excessive.
I don't understand that. As far as I understood your first post in this threat, the adhesion-numbers and numwheels work together as a cut-off value for TE. Therefor it wouldn't matter if adhesionis = x, y, 2, z and numwheels = 8 or adhesion = x, y, 0.25 and numwheels = 1. Both numbers shoud result in the same effect. Am I wrong? Also, which entry of numwheesl is it, that you a referring to. The first one (in the wagon-section) or the second one (engine-section)?
MAik
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jtr1962 (95 posts)
Apr-09-02, 12:22 PM (EST) 9. "RE: Interesting findings regarding the Adheasion parameter" >>Another point to mention, unless you
>>also change the third parameter
>>in the adhesion line to
>>1, putting numwheels at 1
>>will result in everything being
>>multiplied by the value you
>>use in that parameter. Now
>>as you are aware, as
>>the speed increases, the TE
>>drops and having the MTE
>>value being the limiting factor
>>will no longer work, as
>>your TE at speeds above
>>CTE will be excessive. The way the sim calculates TE, at least for diesel locomotives, is to take the lesser of either the combination of Adheasion/Numwheels or MaxContinuousForce(or MaxForce between about 13 and 26 mph). In both cases, the resulting power may not exceed what the MaxPower parameter is set for, so regardless of how high Adheasion/Numwheels, MaxForce, or MaxContinuousForce are set for, MaxPower will be the ultimate limiting factor. For example, an SD90MAC develops 6000HP, which means that it can only develop 185,000 pounds of TE at or below the speed of 12.16 mph, regardless of what the other parameters are set for. With electrics, it is a little different, as the curves posted above show, although the only difference is that a 6000 HP electric locomotive will not develop 6000 HP over the entire non-TE limited portion of the power curve, unlike a diesel locomotive, which will. It is therefore necessary when setting the parameters for electric locomotives to adjust the MaxPower parameter until you get the rated power at the rated speed. In the case of the HHP-8, I wanted 8000 HP @ 125 mph, so I had to use 8950 HP in the MaxPower parameter to account for the tractive effort drop-off shown in the graph. This also gives a realistic overload capability which all electric locomotives have since their power is not limited by their prime mover(i.e. the diesel engine in diesel locomotives). In point of fact, their "prime mover" is the generating station on terra firma.
>
>
>I don't understand that. As far
>as I understood your first
>post in this threat, the
>adhesion-numbers and numwheels work together
>as a cut-off value for
>TE. Therefor it wouldn't matter
>if adhesionis = x, y,
>2, z and numwheels =
>8 or adhesion = x,
>y, 0.25 and numwheels =
>1. Both numbers shoud result
>in the same effect. Am
>I wrong?Those should both give the same effect. It is possible to have NumWheels=1 all the time, and simply adjust the first three values in the Adheasion parameter. The point of doing it by using the NumWheels parameter is that once you get Adheasion set for a proper ratio of sliding, normal, and sanding adhesion, you can adjust NumWheels to account for locomotives that have less than 100% of their weight on the drivers.>Also, which entry
>of numwheesl is it, that
>you a referring to. The
>first one (in the wagon-section)
>or the second one (engine-section)?The one in the engine section. As far as I have been able to determine, the one in the wagon section is not used at all.As I mentioned when I started this topic, Adheasion and Numwheels should be set up to properly reflect the sanding, normal, and slipping adhesion values. It is wrong to simply set these very high, and use MaxContinuousForce(and MaxForce) to limit the TE since you will have the same MTE in all weather conditions. Doing it my way, the sim will realistically reduce the available TE to account for rain(0.9), snow(0.55), and tunnels(0.8). These can be adjusted in the default.wag file, and based on what Bob said about running on ice being closer to running in the rain due to the huge contact pressures, I think the factor for snow should maybe be more like 0.75 instead of 0.55.
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b101uk (57 posts)
Apr-09-02, 11:03 PM (EST) 10. "RE: Interesting findings regarding the Adheasion parameter" hi
y do you guys make it harder than it actualy is, its quit a simply proses to figer out there is nothing odd or hard to work out and yet you go and over complecate things with long divishons when the end resualt is the same,also dont you wont the chanse of 100% compatabilaty with MSTS2 when it comes out and the changes it brings with it?.1: MaxForce = the max TE a loco can produce at speeds genraly LESS than <9-15mph ONLY (sume times as low as 6mph).
2: MaxContinuousForce = the point at witch the Continuous use of the max power seting or R8 can be used without damageing any of the motors threw heat bildup or the point at witch max power(HP) can be used without wheel slip.
3: the Mass seting DOSE have a efect on TE out put in the rain,snow and sume times in dry.
4:the 3rd Adheasion has NOTHING to do with sanding it js just a divishon factor.
5:NumWheels is just a divishon factor nothing more.
6:the only time that your dry rail sanding TE is higher than your non sanding dry rail TE(Any speed) is when you have to low an amout of Adheasion in the 1st place and are no longer puting out the TE spesifide in the MaxForce part of the eng file you get the same efect with the defualt dash9 if you put 0.2 for the 2nd Adheasion value. this is made even worse if you are only useing observed TE values insted of rated values.
7:the 2nd Adheasion value is not for "normal conditions" it is for the minimum % of Adheasion eg the amout of % Adheasion you would expect to get in snow.
8:the 1st Adheasion value is wheelslip as stated in the tec docs this value should alwase lower than the 2nd Adheasion value, this is also a % Adheasion, this is the amount you must back of the power in order to recover from wheel slip, this is the % Adheasion you have when your wheels are sliping.
9: i stand by my statment in my prior post that 1st & 2nd Adheasion values simply calculated
by geting the requrid % of Adheasion /100 then -0.02 to 0.03 from from that number(-0.025 if you wont to be real lazy).hear are a fue graphs to show sume of the resualt i foud useing both yous & my method, the graph show the that there is no difrens in the end resualt or any advantage to useing any of the methods other than the amout of calculations you have to do to get the requird TE resualt,the defualt dash9 was used for the test useing the same consist and track section
of my test track, the only changes to the dash9 file is the Mass was set to 183.756t (405000LB) and Adheasion,NumWheels was change witch is listed in name of each graph curve along with rail condishon and sanding state.AntiSlip () was used for all test.
the resualt are not ment to replecate the real dash9.graph1 shows snow TE from 0 to 70mph useing both the NumWheels devider and a singlur 2nd Adheasion value change. all setings are as the defualt dash9 other than named changes.
graph2 shows Dry TE from 0 to 70mph.
graph3 shows snow TE with sanding ON from 0 to 70mph.
graph4 shows 2 matching snow TE curves from 0 to 40mph useing both difrent methods.
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plainsman (835 posts)
Apr-10-02, 00:58 AM (EST) 11. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-10-02 AT 01:21 AM (EST)I think I am following a portion of what you are attempting (I must admit without trying to insult you, your writing skills make your reasoning very, very difficult to follow) to say. If you are saying it is possible to adjust the factors without using values for either the adhesion multiplier or the numwheels divisor, I think Joe and I have both agreed you can get about the same results in most conditions if you put the correct values in place. I don't understand nor likely agree with some of the points you make. For example, your assertion about observed vs rated output is at best unwarranted and probably absurd. Manufacturers rate locomotives for different reasons many of which have little to do with pulling power, some may relate more to marketing. If Baldwin builds a locomotive with a new higher amp traction motor and gets 2650 HP on the rail, Alco will want to claim they can get 2700 HP on the rail in order to sell locomotives. Independant test data is the most reliable objective way to assess the real performance of a locomotive. I don't think anyone is confused by the methods Joe and I prefer. In the long run, it may yield a better match to the eventual MSTS2, who knows (unless you work with KUJU, in which case all I can say is the default data (not the equations) show the level of knowledge to which KUJU studied the equipment (see above absurd weight data)).
I still don't really follow your method in point 9, other than it forms a "rule of thumb"?? Maybe I am also confused by your math (35%-2%=32%??? (see above)).
BobBTW Joe, Interestingly enough, the actual output of an AC6000CW is 6200 HP. I also agree, maybe 80-85% for wet and 70-75% ice. Remove | Alert Edit | Reply | Reply With Quote | Top
b101uk (57 posts)
Apr-11-02, 00:18 AM (EST) 12. "RE: Interesting findings regarding the Adheasion parameter" hi
RE:"Maybe I am also confused by your math (35%-2%=32%??? (see above))."are yes i see now, i did not see that yes the could well lead to
be being confused the perils of late nights and Ctrl C, Ctrl V
and bad speling!RE:"I still don't really follow your method in point 9, other than it forms a "rule of thumb""Yes it is a "rule of thumb" but its quite good 1 it has an avrage error of +-1560LB TE so far in tests with locos with mass's from 93t to 207t,& HP rateing from 2000hp to 6844hp & with MSTE's rateings from as low as 28% of mass up to 36% of mass.for the tests the same -0.025 convershon factor was used for the 2nd minimum % of Adheasion value(point 9)
so for a minimum % of Adheasion(snow) of 21% i used 0.185.
for a minimum % of Adheasion(snow) of 29% i used 0.265.
for a minimum % of Adheasion(snow) of 23% i used 0.205.
for a minimum % of Adheasion(snow) of 19% i used 0.165.loco#1
had a mass of 94t (204974LB)
a MaxPower of 2677hp
a MaxForce of 57392LBF (28% of mass)
a MaxContinuousForce of 48783LBF (85% of MaxForce)
& Adheasion ( 0.1 0.165 2 0 ) (19% minimum Adheasion)
my expected TE for this loco was 38945LB(19%) in snow, the actual TE i got was 37187LB, an error of -1758LB.

loco#2
had a mass of 129t (284316LB)
a MaxPower of 2000hp
a MaxForce of 88138LBF (31% of mass)
a MaxContinuousForce of 73154LBF (83% of MaxForce)
& Adheasion ( 0.1 0.185 2 0 ) (21% minimum Adheasion)
my expected TE for this loco was 59706LB(21%) in snow, the actual TE i got was 57835LB, an error of -1871LB.

loco#3
had a mass of 176t (387904LB)
a MaxPower of 3435hp
a MaxForce of 139645LBF (36% of mass)
a MaxContinuousForce of 121491LBF (87% of MaxForce)
& Adheasion ( 0.1 0.265 2 0 ) (29% minimum Adheasion)
my expected TE for this loco was 112492LB(29%) in snow, the actual TE i got was 113029LB, an error of +537LB.

loco#4
had a mass of 207t (456228LB)
a MaxPower of 6844hp
a MaxForce of 187053LBF (41% of mass)
a MaxContinuousForce of 149624LBF (80% of MaxForce)
& Adheasion ( 0.1 0.205 2 0 ) (23% minimum Adheasion)
my expected TE for this loco was 104932LB(23%) in snow, the actual TE i got was 102838LB, an error of -2094LB.i wont bother listing all the locos the ones above have the bigest errors expected TE.as the resualts show there is an avrage error of about 1500lb of TE in snow from the expected TE(% of Adheasion) as enterd in the 2nd Adheasion value.i also tested the NumWheel 2/3/4/5 with Adheasion(0.X 0.X 1.X)
and found that it canot be used as a constant due to the huge error +->48000lb(NumWheel5) +-24000lb(NumWheel4) and so on caoused by the devider(the same error is in the method i use) when tring to aply the same Adheasion & numwheel values to difrent locos like a "rule of thumb" to get an expected TE in bad wether(snow).B101UK Remove | Alert Edit | Reply | Reply With Quote | Top
jtr1962 (95 posts)
Apr-11-02, 09:29 AM (EST) 13. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-11-02 AT 09:38 AM (EST)OK, I finally understand what you're trying to do. As Bob mentioned, the reason I didn't understand previously was your combination of bad spelling and grammer(no offense, if I'm correct English is not your native language, and I wouldn't do any better posting in French or German, or Italian). You're setting the first and second values of the Adheasion parameter to low enough numbers that they limit the TE under rain, and snow conditions, and then using MaxForce and MaxContinuousForce to make sure the sanding and normal TE values, respectively, are realistic. This will work fine for diesel locomotives. The point at which you may run into a problem is with electric locomotives because changing the MaxContinuousForce parameter also alters the TE curve, as shown by the graph in my initial post. In fact, that is the reason why I now use my method. I can make the normal, rain, snow, and sanding adhesion to whatever I want them to be just using the Adheasion and NumWheels parameters, and then I can play with the MaxContinuousForce and MaxPower parameters to alter the TE curve on electric locomotives to be closer to reality. All my method does is give me a little more control over the TE curve(for electrics only). For diesels, there is no difference, and I would say your method is as good as mine.BTW, if you want to get no error for TE while in the snow, just use the following equation to calculate the second value of the Adheasion parameter:second value = (snow adhesion)/.55*2 = (snow adhesion)/1.1For a snow adhesion of 23%(as you used for loco #4) you would use
0.23/1.1 = 0.209 for the second value. My equation assumes that you are keeping the snow adhesion value in the default.wag file at the original 0.55 value, and that you always use 2 for the third value of the Adheasion parameter. No need for a "rule of thumb" anymore, you can calculate everything exactly. Remove | Alert Edit | Reply | Reply With Quote | Top
b101uk (57 posts)
Apr-11-02, 06:29 PM (EST) 14. "RE: Interesting findings regarding the Adheasion parameter" LAST EDITED ON Apr-11-02 AT 06:34 PM (EST)hi
i am sorry to say that English is my native language ,
i take no offense to your coments, as i no most if not all people can spell English beter than me!.RE:"For a snow adhesion of 23%(as you used for loco #4) you would use
0.23/1.1 = 0.209 for the second value."yes that dose work very well for all the locos with no error if used to 6 places 0.xxxxxx (avrage-+15LB).i did no that "Mass ( xxxt/1.1023 )"(US to metric on an alredy metric tone) gave the corect snow TE(+200lb) if the second value was enterd at the requird % but i never liked useing it becouse of the REAL LIFE HP to tone link with top speed and grade perfomance (mph) and the fact that the Mass value should be in metric tones, also i just asumed it was resedue from poor programing so i had always tride to aply a subtract -0.xxxx from the 2nd value to give near corect snow TE, + i did not see haw the link with the 0.55(snow) and 2(3rd value) worked.

but i never would have thort to use a /1.1 to get the 2nd adhesion value as i allways tri and avoid / & * in maths as i perfer + & - sums as you can avoid eg 5.333333R.useing your /1.1 method and my apx -0.025 method you dont have to do any maths just useing as you can aply it strate to the % value and the sim dose the rest eg "Adheasion ( 0.xx/1.1 0.xx/1.1 2 0 )"
my vershon "Adheasion ( 0.xx-0.025 0.xx-0.025 2 0 )". (not that -0.025 is hard) well done on the /1.1 methodb101uk Remove | Alert Edit | Reply | Reply With Quote | Top
mBusolt (5 posts)
Apr-12-02, 02:38 AM (EST) 15. "RE: Interesting findings regarding the Adheasion parameter" >BTW Joe, Interestingly enough, the actual
>output of an AC6000CW is
>6200 HP.Where is this output measured? Is it the output of the prime mover, the generator or is it the power output of the locomotive at the rails? Where is the rated power of a american diesel-locomotive generally measured? I think in germany the rated power refers to the power of the prime mover and the engines can only transform a fraction of this into TE and speed.Maik
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Jeff (15 posts)
Apr-12-02, 05:50 PM (EST) 16. "RE: Interesting findings regarding the Adheasion parameter" Adhesion is not the percentage of the loco/wagon weight. To determine adhesion you need the tractive/retarding force and weight. Changing the variables in the adheasion and numwheels lines means you are changing the weight and braking force of the wagon and for locos changing the tractive/dynamic/brake forces, weight and horsepower. Take no notice of Kuju’s explanation. They got it completely wrong.If you don’t believe me from memory in notch 1 a Dash 9 puts out about 60 KN, dropping off after about 16 km/h. 60KN and the loco weight requires about a 3% adhesion demand. From the tractive effort, weight, static and rolling resistance you can work out how fast the loco will accelerate at various speeds. So from standing start in notch 1 the acceleration rate will go from 0km/h/min slowly building up as it overcomes the static resistance then more quickly to roughly 50-60km/h/min at say 12km/h. Acceleration stabilises then starts to drop off as tractive effort reduces with speed and rolling resistance increases. Eventually the loco will reach a balance speed, where the tractive effort is the same as the resistance forces.In train sim the acceleration and deceleration are instant. In notch 1 acceleration will build instantly to say 80-90 km/h/min then start to reduce with speed. Close the throttle and the acceleration rate disappears virtually instantly. Change the adhesion/numwheels values the acceleration rate changes (tractive effort). It’s still instant though. When it comes to hauling a train say if you work out that a Dash 9 can pull a certain weight up a certain grade and change the adhesion/numwheels variable to achieve that. Everywhere else the required tractive effort and the speed obtained will be completely wrong and the acceleration/deceleration rates are just plain weird. 8000 tonnes accelerating from 3km/h/min to 20 km/h/min instantly is ridiculous. The air brake, how locos put out their power, wheel slip, grade resistance, static and rolling resistance are just as bad as the adhesion modelling. The values used in the resistance update are incorrect as well. Being anywhere from 100% too low or too high depending on speed. It is not possible to get realistic values using Kuju’s formula. It is impossible to model a train’s performance realistically in train sim. I honestly can’t find one area where the modelling is correct. The headlight switch works great though. Hopefully Kuju will take some notice of the train physics formulas emailed to them.Jeff Remove | Alert Edit | Reply | Reply With Quote | Top
jtr1962 (95 posts)
Apr-13-02, 07:20 AM (EST) 17. "RE: Interesting findings regarding the Adheasion parameter" >Changing the
>variables in the adheasion and
>numwheels lines means you are
>changing the weight and braking
>force of the wagon and
>for locos changing the tractive/dynamic/brake
>forces, weight and horsepower. Take
>no notice of Kuju s explanation.
>They got it completely wrong. The Adheasion and NumWheels parameters change the maximum possible tractive effort and braking(for locomotives only), which means if they are set for a certain amount, say 32% of locomotive weight, then no matter how how high you set MaxContinuousForce and MaxForce for, 32% of locomotive weight is the maximum TE you will get. Unfortunately, these parameters have zero effect with the braking behavoir of wagons, despite Kuju's documentation to the contrary. Kuju's explanation of the Adheasion parameter is also partially incorrect.>If you don t believe me from
>memory in notch 1 a
>Dash 9 puts out about
>60 KN, dropping off after
>about 16 km/h. 60KN and
>the loco weight requires about
>a 3% adhesion demand. From
>the tractive effort, weight, static
>and rolling resistance you can
>work out how fast the
>loco will accelerate at various
>speeds. So from standing start
>in notch 1 the acceleration
>rate will go from 0km/h/min
>slowly building up as it
>overcomes the static resistance then
>more quickly to roughly 50-60km/h/min
>at say 12km/h. Acceleration stabilises
>then starts to drop off
>as tractive effort reduces with
>speed and rolling resistance increases.
>Eventually the loco will reach
>a balance speed, where the
>tractive effort is the same
>as the resistance forces.
>
>In train sim the acceleration and
>deceleration are instant. In notch
>1 acceleration will build instantly
>to say 80-90 km/h/min then
>start to reduce with speed.
>Close the throttle and the
>acceleration rate disappears virtually instantly.
>Change the adhesion/numwheels values the
>acceleration rate changes (tractive effort).
>It s still instant though. I believe there are parameters called RunUpTimeToMaximumForce and DieselEngineMaxRPMChangeRate that allow you to get a slower buildup in power. All I know is that many of the diesels that I have run with modified .eng files certainly don't have instantaneous changes in acceleration. It is true in the lower notches that at low speeds you only get a proportional % of the maximum TE, but this is hard-coded into the program, so much as I would like to fix it, I can't.Regarding the %power in the notches being wrong, I have personally corrected this in a few of my .eng files. You also have to change a few things in the .cvf files so the notch numbers display correctly. However, you're still stuck with the silly proportional % of TE at low speeds.>The air brake, how locos put
>out their power, wheel slip,
>grade resistance, static and rolling
>resistance are just as bad
>as the adhesion modelling.As originally done by Kuju, you are 100% correct. I've never driven a real train in my life(although I've ridden in them 100s of times), and the first time I tried MSTS, too many things just felt wrong. Most of these things have be corrected as much as possible within the limits of the sim. As far as I know, grade resistance was always modeled correctly. Despite having a place in the .eng and .wag files for curvature resistance, it is not used at all by the sim, and this is an unacceptable oversight. Once again, I don't think it would be possible to model curvature resistance 100% correctly anyway with Kuju's silly formula.>The values used in the resistance
>update are incorrect as well.
>Being anywhere from 100% too
>low or too high depending
>on speed. It is not
>possible to get realistic values
>using Kuju s formula. Which resistance update are you referring to? Do you mean fcalc_10(the one that I did), or was there another one someone else did that I'm unaware of? You're correct, it is not possible to get 100% correct values using Kuju's silly equation, but my modification is within 1% or 2% of the AAR recommended value all the time. I even included graphs and a detailed analysis with my update. One thing that cannot be modeled is the extra resistance at zero velocity of friction bearing trucks so that some extra TE is required to start the train rolling from a dead stop. This phenomenon is not exhibited to any great extent with modern roller bearing trucks, however, so for those my update is largely correct. Kuju really should have modeled the train resistance with the usual 3 constants(R = A + BV + CV²), and included an optional fourth for zero velocity resistance so that friction bearing trucks could be correctly modeled.>It is impossible to model a
>train s performance realistically in train
>sim. I honestly can t find
>one area where the modelling
>is correct. The headlight switch
>works great though. Hopefully Kuju
>will take some notice of
>the train physics formulas emailed
>to them. Would you mind either posting those equations here, or e-mailing them to me? There may be more that can be done to increase the sim's realism. I'm certainly not defending Kuju here, just pointing out that many of the deficiencies you mentioned have been addressed as much as possible with the limits of the bad physics Kuju used.Some of the "bugs" have to do with the finite timesteps used by the sim to calculate train speed and position. For example, take the notorious coupler bug. If you increase timestep from the default 10ms(it can be altered in the default.wag file), the problem gets worse. Increasing it to 50 ms or more almost guarantees a broken coupler or derailment instantly. I would imagine decreasing the timestep to, say 0.1 ms, would make the problem go away entirely, but you would need a Cray to play the sim on. When I went from 10 ms down to 5 ms, the frame rates on my PII450 dropped to unacceptable levels, especially with freight trains. A fast machine might be able to handle 2 ms comfortable, however, and this might largely solve the problem. Remove | Alert Edit | Reply | Reply With Quote | Top
b101uk (57 posts)
Apr-13-02, 10:26 PM (EST) 18. "RE: Interesting findings regarding the Adheasion parameter" hi
RE:"The Adheasion and NumWheels parameters change the maximum possible tractive effort and braking(for locomotives only), which means if they are set for a certain amount, say 32% of locomotive weight, then no matter how how high you set MaxContinuousForce and MaxForce for, 32% of locomotive weight is the maximum TE you will get.i think the above statment is not completly true.
1:the NumWheels will change the maximum possible tractive effort, as stated.2: the 2nd Adheasion % value changes the minimum TE the loco will produce in the worst rail condishons(snow),A:if the later part of your above statment is corect, then useing loco#4 from my prior post with its 23% Adheasion and your /1.1 devider(0.23/1.1 Adheasion value) it should deliver
NEVER MORE than 104932LB(23% Adheasion) of TE even on a dry rail.B:but if my statment is true that the 2nd Adheasion value is for minimum TE the loco will produce in the worst rail condishons(snow). then i should get 104932LB of TE in snow only and a higher amount TE in the rain and the full TE in the dry.This graph shows TE v speed in the Dry,Rain,Snow for loco#4 from my prior post with only a change to the Adheasion values useing your /1.1 devider so entry in the .eng file looked like this "Adheasion ( 0.18/1.1 0.23/1.1 2 0 )"as you can see from the graph the TE got higher as it changed from snow,rain,dry rail condishons this would meen that later part of your statment is incorect, and that my statmens from prior posts is corect as far as the "2nd Adheasion % value changes the minimum TE the loco will produce in the worst rail condishons(snow)" could be true?3: you statment that MaxContinuousForce and MaxForce are limeted by the 2nd Adheasion % value is corect, if you take loco#4 used in the above graph and add 500000LBF to the MaxForce and 400000LBF to the MaxContinuousForce and the sim will only let it produce 190660.142LB of TE max, i beleve the sim calculats this by takeing the minimum snow TE % (2nd value) "minimum TE LB*2/1.1=MaxForce". or in the case of loco#4
104863.0781LB*2=209726.1562LB/1.1=190660.142LB.also something that has been buging me is that a devider of
/1.099565 seems to work down to an error of 0.01LB on locos#1 to#4, yet if the /1.1 is used then the error is about 20-30LB. do you not think thats a bit odd given the simple /0.55*2. or /1.1 maths involved and the fact that train sim normaly works to 6 or more desamal places when it dose calculations?."In train sim the acceleration and deceleration are instant." jeffi do find that quite an odd statment. and somthing i have never seen in train sim even with silly trains that can do more than >40000mph.
B101UK Remove | Alert Edit | Reply | Reply With Quote | Top
jtr1962 (95 posts)
Apr-14-02, 04:47 PM (EST) 20. "RE: Interesting findings regarding the Adheasion parameter" >hi
>as you can see from the
>graph the TE got higher
>as it changed from snow,rain,dry
>rail condishons this would meen
>that later part of your
>statment is incorect, and that
>my statmens from prior posts
>is corect as far as
>the "2nd Adheasion % value
>changes the minimum TE the
>loco will produce in the
>worst rail condishons(snow)" could be
>true? The second Adheasion value is used to calculate the maximum dry adhesion. The sim uses 90% of the dry adhesion value for the rain, 80% for tunnels, and 55% for snow, so changing the second value will change the dry, rain, and snow adhesion values simultaneously. Reread my initial post carefully, and you'll see that I'm saying the same thing as you are. The graph you have shows this behavoir exactly. If you use my 1.1 method to calculate the minimum(snow) adhesion, you will also get reasonable values for the dry and rain adhesion. In the case of loco 4, the snow adhesion is 0.23. Since this is 55% of the dry adhesion, this means the dry adhesion is .23/.55 = 0.418, which is reasonable for an AC locomotive. >also something that has been buging
>me is that a devider
>of
>/1.099565 seems to work down to
>an error of 0.01LB on
>locos#1 to#4, yet if the
>/1.1 is used then the
>error is about 20-30LB. do
>you not think thats a
>bit odd given the simple
>/0.55*2. or /1.1 maths involved
>and the fact that train
>sim normaly works to 6
>or more desamal places when
>it dose calculations?.I think MSTS only calculates to a finite number of decimal places. I wouldn't worry about 20 or 30 LBS error The truth is that real locomotives of the same model vary in performance by quite a bit more than that, sometimes even a couple of percent. Remove | Alert Edit | Reply | Reply With Quote | Top
SP9800 (244 posts)
Apr-14-02, 03:57 AM (EST) 19. "RE: Interesting findings regarding the Adheasion parameter" >I believe there are parameters called
>RunUpTimeToMaximumForce and DieselEngineMaxRPMChangeRate that allow
>you to get a slower
>buildup in power.As far as I can tell, DieselEngineMaxRPMChangeRate does nothing except control how fast the sounds and smoke change.RunUpTimeToMaxForce causes problems when running in reverse. The engine accelerates extremely fast, and when you close the throttle it will try to continue accelerating. This is a big issue for engines that may be expected to do any switching, as you shouldn't have to go into emergency to stop before the end of an industrial spur. Remove | Alert Edit | Reply | Reply With Quote | Top
jtr1962 (95 posts)
Apr-14-02, 04:57 PM (EST) 21. "RE: Interesting findings regarding the Adheasion parameter" >As far as I can tell,
>DieselEngineMaxRPMChangeRate does nothing except control
>how fast the sounds and
>smoke change. I think you're correct here.
>RunUpTimeToMaxForce causes problems when running in
>reverse. The engine accelerates
>extremely fast, and when you
>close the throttle it will
>try to continue accelerating.
>This is a big issue
>for engines that may be
>expected to do any switching,
>as you shouldn't have to
>go into emergency to stop
>before the end of an
>industrial spur.The problem here is that when running forwards, power increases occur slowly, while power decreases are still instantaneous(another MSTS bug). When running in reverse, the opposite is true. Power increases are now instantaneous while power decreases are not, so when you notch down in reverse it might take 20 or 30 seconds for the power to go to zero, depending upon what value is in RunUpTimeToMaxForce. Therefore, I certainly wouldn't use this parameter at all in a switching engine. The more I'm learning the more I see how badly the physics end of it was handled by Kuju. Remove | Alert Edit | Reply | Reply With Quote | Top

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