[edwardk]

I am now beginning to use the full OR template. The first is for SLI's Mactier set which I downloaded from Trainsim. I already know what parameter represents the gross hp so all I need to know is how the rail hp is calculated?

[R H Steele]

edwardk, on 11 December 2019 - 07:05 PM, said:

I am now beginning to use the full OR template. The first is for SLI's Mactier set which I downloaded from Trainsim. I already know what parameter represents the gross hp so all I need to know is how the rail hp is calculated?

I find the Rail hp by using the efficiency values and Generator\Alternator HP ( traction hp ) --- Bob Boudoin has accurate values as does Derek Morton.
I don't know how OR computes the rail hp from available data. I believe it is shown in the loco HUD, although I'm not sure which value is used...Peter Newell would know. I do know that I use it to calculate the ORTS Max Tractive Curves. I'm working on a version 2 of the Std Engine files ( version 1 was used in the conversion kits available at TS - which I think you are referring to "SLI's Mactier"). Attached is a sample of version 2 for the SD40-2, power ratings are given in the comments section. Also attached is the spreadsheet used to calculate the max tractive curves.

Comment ( VER2 Standard ORTS Diesel Engine for EMD SD40-2 & SD40T2, and safety cab "W" model )
Comment ( Data from Bob Boudoin Engine physics and Derek Morton Train physics )
Comment ( ORTSCurtius_Kniffler ( 9.429 90.537 0.161 0.7 ) )
Comment ( Power Ratings == Gross HP 3150 == Traction HP 3000 == Rail HP 2520 )
Comment ( Coninuous Tractive Effort 83089lb @ 11.23mph == 84%eff. == Stating Tractive Effort 103408lb )
Comment ( Mass 390218lbs = 177.0t == metric, Adhesion Factor = 26.5% )
Comment ( Mass×Adhesion Factor = Starting Tractive Effort )
Comment ( Brake HP -- bhp = Power-at-the-shaft = Gross HP or MaximalPower )
Comment ( Traction HP = Alternator/Generator Input HP )
Comment ( Gross HP per technical specs or lacking good data == add 130hp to 150hp to Traction HP )
Comment ( include ( "..\\..\\Common.inc\\Locomotives\\Std_Eng_SD40-2.inc" ) )

ORTSDieselEngines ( 1			
	Diesel (		
	IdleRPM ( 255 )		
	MaxRPM ( 904 )		
	StartingRPM ( 155 )		
	StartingConfirmRPM ( 305 )		
	ChangeUpRPMps ( 84 )		
	ChangeDownRPMps ( 53 )		
	RateOfChangeUpRPMpSS ( 13 )		
	RateOfChangeDownRPMpSS ( 8 )		
	MaximalPower ( 2348955W )		
	IdleExhaust ( 1.2 )		
	MaxExhaust ( 2.2 )		
	ExhaustDynamics ( 1.6 )		
	ExhaustDynamicsDown ( 0.8 )		
	ExhaustColor ( 20161819 )		
	ExhaustTransientColor ( 40212324 )		
	DieselPowerTab (		
		0	0
		318	293806
		402	587612
		486	880672
		570	1174478
		654	1468283
		738	1762089
		822	2055149
		904	2348955
	)		
	DieselConsumptionTab (		
		0	0
		255	19.7
		904	622.3
	)		
	ThrottleRPMTab (		
		0	255
		12.5	318
		25	402
		37.5	486
		50	570
		62.5	654
		75	738
		87.5	822
		100	904
	)		
	DieselTorqueTab (		
		0	0
		318	70534
		402	55795
		486	46152
		570	39350
		654	34296
		738	30393
		822	27287
		904	24812
	)		
	MinOilPressure ( 30psi )		
	MaxOilPressure ( 90psi )		
	MaxTemperature ( 120degc )		
	Cooling ( 3 )		
	TempTimeConstant ( 720 )		
	OptTemperature ( 71degc )		
	IdleTemperature ( 55degc )		
	)		
)
ORTSEmergencyCausesThrottleDown ( 0 )
	ORTSWheelSlipCausesThrottleDown ( 0 )
	ORTSMainResChargingRate ( 0.4psi/s )
	ORTSBrakePipeChargingRate ( 200psi/s )
	ORTSEngineBrakeReleaseRate ( 38psi/s )
	ORTSEngineBrakeApplicationRate ( 34psi/s )
	ORTSBrakePipeTimeFactor ( 0.003 )
	ORTSBrakeEmergencyTimeFactor ( 0.1 )
	ORTSBrakeServiceTimeFactor ( 1.009 )
	TrainPipeLeakRate ( 0.0833psi/s )
	TrainBrakesControllerMaxReleaseRate ( 10psi/s )

MaxForce ( 460298N )
MaxContinuousForce ( 369598N )
ORTSMaxTractiveForceCurves (					
		0 (			
			0	0	
			4.03	0	
			4.65	0	
			5.50	0	
			6.53	0	
			7.91	0	
			9.83	0	
			12.52	0	
			16.54	0	
			22.35	0	
			31.29	0	)
	0.125 (				
			0	57538	
			4.03	57538	
			4.65	49875	
			5.50	42170	
			6.53	35527	
			7.91	29305	
			9.83	23577	
			12.52	18525	
			16.54	14019	
			22.35	10374	
			31.29	7410	)
	0.25 (				
			0	115075	
			4.03	115075	
			4.65	99749	
			5.50	84340	
			6.53	71054	
			7.91	58609	
			9.83	47154	
			12.52	37050	
			16.54	28038	
			22.35	20748	
			31.29	14820	)
	0.375 (				
			0	172612	
			4.03	172612	
			4.65	149623	
			5.50	126510	
			6.53	106581	
			7.91	87914	
			9.83	70731	
			12.52	55574	
			16.54	42056	
			22.35	31122	
			31.29	22230	)
	0.50 (				
			0	230149	
			4.03	230149	
			4.65	199497	
			5.50	168680	
			6.53	142107	
			7.91	117218	
			9.83	94308	
			12.52	74099	
			16.54	56075	
			22.35	41496	
			31.29	29640	)
	0.625 (				
			0	287687	
			4.03	287687	
			4.65	249371	
			5.50	210850	
			6.53	177634	
			7.91	146523	
			9.83	117885	
			12.52	92624	
			16.54	70094	
			22.35	51869	
			31.29	37050	)
	0.75 (				
			0	345224	
			4.03	345224	
			4.65	299245	
			5.50	253020	
			6.53	213161	
			7.91	175827	
			9.83	141461	
			12.52	111148	
			16.54	84112	
			22.35	62243	
			31.29	44460	)
	0.875 (				
			0	402761	
			4.03	402761	
			4.65	349119	
			5.50	295190	
			6.53	248687	
			7.91	205132	
			9.83	165038	
			12.52	129673	
			16.54	98131	
			22.35	72617	
			31.29	51869	)
	1.0 (				
			0	460298	
			4.03	460298	
			4.65	398993	
			5.50	337360	
			6.53	284214	
			7.91	234436	
			9.83	188615	
			12.52	148198	
			16.54	112150	
			22.35	82991	
			31.29	59279	)
		)

Attached thumbnail(s)

• 
• 

[steamer_ctn]

Tractive Effort (Force) is the key factor in driving a train forward, as the tractive force needs to overcome the resistance force of the train for it to move. The hp is more a convenient way of comparing locomotives.

Thus I believe that the key parameters in defining the power of a diesel locomotive are:
MaxForce - starting tractive effortMaxContinuousForce - maximum sustainable force at speed x.
ORTSSpeedOfMaxContinuousForce - speed at which maximum force is measured.
MaxPower - maximum power that is created at the above two conditions. (Also Rail Power)

The MaxPower can be calculated by the formula - HP = Cont Force (lbf) x Speed (mph) / 308 - at the above point

These values should be reasonably readily available from the Internet.

By default OR calculates the Tractive Force based upon the above parameters. Based upon my review (so far) it appears to match the HP curve reasonably closely.

Attached is a test report graph for the Tractive Force of a BR diesel. Notice the drop off in force at higher speeds.

I believe that it is only worth the effort in generating tractive force curves when one wishes to model this drop off effect, or one has a manufacturers set of curves, otherwise the OR calculations should be close enough.

Attached thumbnail(s)

• 

[edwardk]

I should have majored in Computer Science :) I am guessing that MaxPower() is still used? Its not used in the OR files, but the remaining information is still taken from the msts file.

Edit: Should MaxPower() be included in the OR files since both MaxForce() and MaxContinuousForce() are included?

[R H Steele]

steamer_ctn, on 12 December 2019 - 01:20 AM, said:

I believe that it is only worth the effort in generating tractive force curves when one wishes to model this drop off effect, or one has a manufacturers set of curves, otherwise the OR calculations should be close enough.

The question is: How does OR calculate tractive force curves? What parameters are used in the calculations? Otherwise, why have the option in the manual to use ORTSMaxTractiveCurves, if it has no use.

[steamer_ctn]

edwardk, on 12 December 2019 - 03:45 AM, said:

Edit: Should MaxPower() be included in the OR files since both MaxForce() and MaxContinuousForce() are included?

I believe that it should be used, as it appears to set an upper limit for the amount of force generated by the locomotive, however I haven't fully completed any detailed testing to confirm this.

R H Steele, on 12 December 2019 - 09:31 AM, said:

Otherwise, why have the option in the manual to use ORTSMaxTractiveCurves, if it has no use.

In BASIC mode (ie without Traction Curves defined), OR uses the HP formula above generate a smooth curve for the tractive force.

In ADVANCED mode (ie with Traction Curves defined), the user is able to customise the shape of the force curve.

So for example, the curves shown in the earlier post are for a diesel with a maximum velocity of 90mph, and as can be seen from the curves, the tractive force starts decreasing below the "smooth" curve that would be generated in the BASIC mode once the speed rises above approx 60 or 70mph, depending upon the throttle setting. So the value of the tractive force curves is its ability to model actual force curves where they are known from test results or specifications.

As an exercise, it would be interesting to plot the two curves on a spreadsheet, and compare the difference.

[ATW]

Might be related to Tractive Curves at speed an combination of simple controls but do you plan to make speed control governors for notches for modern day diesels as well as remotes? Now a days especially remotes are simple controlled in special notches like MSTS simple controls for example but where you set throttle to idle brakes either independents or train brakes are set to full service to stop the train for rookie like operations.

[steamer_ctn]

In recent weeks I have worked with a number of users to identify some issues with diesel locomotives not moving, etc. The majority of the causes for this problem have been due to ENG files with missing parameters.

So in order to (hopefully) assist users to identify these types of issues, I have added some code (in latest unstable version - post 14/12) to provide some "error" messages. The error messages will advise the value that are "missing" and what value has been set.

These messages by default will only appear if they are "activated", which can be done by ticking the "Verbose ENG/WAG configuration messages" on the "Data Logger" TAB.

This is still a work in progress.

[Genma Saotome]

steamer_ctn, on 14 December 2019 - 06:00 PM, said:

This is still a work in progress.

Thank you!

Might it be possible to do the same for some of the other new features you've added? Its very hard to figure out what's wrong when something important is missing from the .wag or .eng and only a subset of the parameter data is presented in the f5 screens.

[steamer_ctn]

Genma Saotome, on 14 December 2019 - 08:30 PM, said:

Might it be possible to do the same for some of the other new features you've added? Its very hard to figure out what's wrong when something important is missing from the .wag or .eng and only a subset of the parameter data is presented in the f5 screens.

I perceived that this code would be for key parameters that would stop the diesel from running, otherwise there would be too many different combinations.

To confirm that all "relevant" parameters are included I would still prefer to see a well structured ENG file using some of the formatting that I have suggested in other threads.