How can a slug be modelled in .eng/.wag?

[EldoradoRailroad]

First, what is a slug?

https://www.youtube.com/watch?v=Vd3m9VNBWuY

Next, what can we do? A .wag file models an element that is dragged by an element that has motive force/tractive effort. A slug has tractive effort but NO motive force. A slug receives its tractive effort from an element that has motive force/tractive effort, which would be an engine of course. I do not want a fake slug with an "engine", which is currently what I see as examples in the library.

Is there an example .eng that demonstrates how to emulate a slug connected to an engine? The only way that I can see this being implemented is to have a model that has both an engine and slug attached (hopefully articulated at the coupler) and thus the tractive effort is somehow distributed between the engine and the slug. You could never uncouple the slug from the engine.

Is there a better way? Maybe an example to learn from?

Thanks in advance,

Steve

[pwillard]

Oldie but goodie...

	Wagon ( SW_slug )
	Type ( Diesel )
	MaxPower ( 0hp )
	MaxForce ( 250kN )
	MaxContinuousForce ( 290kN )
	RunUpTimeToMaxForce ( 30.0 )
	comment( thats the usable one, full capacity is 5300gal )
	MaxDieselLevel( 0gal ) 
	MaxVelocity ( 65mph )
	MaxCurrent ( 1800A )
	comment( the range of the load meter is 0 to 1800Amps with motoring in green and 0 to 1200A 	with braking in yellow)
	comment( air gauge graph: 40-120psi)
	WheelRadius ( 20in )
	comment( sanding system is switched off when faster than given velocity )
	Sanding ( 6mph )
	NumWheels ( 8 )
	MaxTemperature ( 120 )
	MaxOilPressure ( 90 )

[R. Steele]

Pete, Would than run in OR or just generate a bunch of warnings or errors in the log?

[pwillard]

Its from an old MSTS slug in my collection.

[Der_Hans]

Oldie but goodie...

	Wagon ( SW_slug )
	Type ( Diesel )
	MaxPower ( 0hp )
	MaxForce ( 250kN )
	MaxContinuousForce ( 290kN )
	RunUpTimeToMaxForce ( 30.0 )
	comment( thats the usable one, full capacity is 5300gal )
	MaxDieselLevel( 0gal ) 
	MaxVelocity ( 65mph )
	MaxCurrent ( 1800A )
	comment( the range of the load meter is 0 to 1800Amps with motoring in green and 0 to 1200A 	with braking in yellow)
	comment( air gauge graph: 40-120psi)
	WheelRadius ( 20in )
	comment( sanding system is switched off when faster than given velocity )
	Sanding ( 6mph )
	NumWheels ( 8 )
	MaxTemperature ( 120 )
	MaxOilPressure ( 90 )

This is remarkably similar to the solution that i came up with years ago, with one difference.
I set the "MaxVelocity" line around 10mph for yard slugs and 35mph for road slugs. Those numbers are based on some google research and are approximate.

This should result in a "Slug" unit that will work correctly in both MSTS and ORTS, and should roughly simulate the slug "cutting out" when you pass a certain speed where the slug is not useful anymore.

If I understand correctly, there is no way to properly simulate the effect of the slug using some of the horsepower from the mother unit when operating at low speeds, but at least this way once you pass the 'cut out' speed, the slug will stop providing tractive effort.

[EldoradoRailroad]

Oldie but goodie...

	Wagon ( SW_slug )
	Type ( Diesel )
	MaxPower ( 0hp )
	MaxForce ( 250kN )
	MaxContinuousForce ( 290kN )
	RunUpTimeToMaxForce ( 30.0 )
	comment( thats the usable one, full capacity is 5300gal )
	MaxDieselLevel( 0gal ) 
	MaxVelocity ( 65mph )
	MaxCurrent ( 1800A )
	comment( the range of the load meter is 0 to 1800Amps with motoring in green and 0 to 1200A 	with braking in yellow)
	comment( air gauge graph: 40-120psi)
	WheelRadius ( 20in )
	comment( sanding system is switched off when faster than given velocity )
	Sanding ( 6mph )
	NumWheels ( 8 )
	MaxTemperature ( 120 )
	MaxOilPressure ( 90 )

Thanks for the simplified code post.

When I looked at this one in the library here:

SIMISA@@@@@@@@@@JINX0D0t______

Wagon ( slatsf
	Type ( Engine )
	WagonShape ( slatsf.s )
	Size ( 2.84m 4.6m 16.76m )
	comment( 230000lbs US )
	Mass ( 24t )
	WheelRadius ( 20in )
	InertiaTensor ( Box ( 2.84m 4.098m 17.5m ) )
	Coupling (
		Type ( Automatic )
		Spring (
			Stiffness ( 1e6N/m 5e6N/m )
			Damping ( 1e6N/m 1e6N/m )
			Break ( 5.1e7N 5.1e7N )
			r0 ( 20cm 30cm )
		)
		comment( CouplingHasRigidConnection () )
		Velocity ( 0.1m/s )
	)
	Buffers (
		Spring (
			Stiffness ( 1e6N/m 5e6N/m )
			Damping ( 1e6N/m/s 1e6N/m/s )
			r0 ( 0m 1e9 )
		)
		Centre ( 0.5 )
		Radius ( 1 )
		Angle ( 0.5deg )
	)
	
	Adheasion ( 0.22 0.44 2 0 )
	DerailRailHeight ( 4cm )
	DerailRailForce ( 2.5*24lbs )
	DerailBufferForce ( 200kN )
	NumWheels (	8 )
	Friction (
		100N/m/s		1		-1mph		0		1
		5.1N/rad/s		1		-1rad/s		0		1
	)
	

	BrakeEquipmentType( "Triple_valve, Auxilary_reservoir, Emergency_brake_reservoir" )

	BrakeSystemType( "Air_single_pipe" )
	MaxBrakeForce ( 31.29kN )
	
	EmergencyBrakeResMaxPressure( 110 )
	TripleValveRatio( 2.5 )
	MaxReleaseRate( 15 )
	MaxApplicationRate( 10 )
	MaxAuxilaryChargingRate( 2 )
	EmergencyResCapacity( 10 )
	EmergencyResChargingRate( 25 )
	BrakeCylinderPressureForMaxBrakeBrakeForce( 64 )

	IntakePoint ( -3.33 0.4 FuelDiesel )
	IntakePoint ( 3.33 0.4 FuelDiesel )

	
	
    	Sound ( "..\\..\\GP38\\SOUND\\gp38eng.sms" )
	)

Engine ( slatsf
	
        
	Wagon ( slatsf )
	Type ( Diesel )
	MaxPower ( 10KN )
	comment( est estimated by comparision with dash9 )
	MaxForce ( 115kN )	
	MaxContinuousForce ( 0kN )
	MaxVelocity ( 65mph )
	MaxCurrent ( 1500A ) 
	WheelRadius ( 20in )
	comment( sanding system is switched off when faster than given velocity )
	Sanding ( 18mph )

	NumWheels ( 1 )
	MaxTemperature ( 120 )
	MaxOilPressure ( 70 )

 	
	MaxDieselLevel ( 800gal )
	DieselUsedPerHourAtMaxPower ( 7gal )
	DieselUsedPerHourAtIdle ( 2gal )

	AirBrakesAirCompressorPowerRating( 1.2 )
	AirBrakesMainMinResAirPressure( 15 )
	AirBrakesMainMaxAirPressure( 140 )
	AirBrakesMainResVolume( 8 )
	AirBrakesAirCompressorWattage( 10kw )
	AirBrakesCompressorRestartPressure( 130 )
	AirBrakesAirUsedPerPoundsOfBrakePipePressure( 0.22 )
	AirBrakesIsCompressorElectricOrMechanical( 1 )

	EngineBrakesControllerMinPressureReduction( 6 )
	TrainBrakesControllerMinPressureReduction( 6 )
	EngineBrakesControllerHasProportionalBrake( 1 )
	EngineBrakesProportionalBrakeLag( 0.9 )
	EngineBrakesControllerMaxApplicationRate( 20 )
	TrainBrakesControllerMaxApplicationRate( 20 )
	EngineBrakesControllerMaxReleaseRate( 15 )
	TrainBrakesControllerMaxReleaseRate( 4 )
	EngineBrakesControllerEmergencyApplicationRate( 50 )
	TrainBrakesControllerEmergencyApplicationRate( 50 )
	EngineBrakesControllerMinSystemPressure( 0 )
	TrainBrakesControllerMinSystemPressure( 0 )
	EngineBrakesControllerMaxSystemPressure( 90 )
	TrainBrakesControllerMaxSystemPressure( 90 )
	EngineBrakesControllerEmergencyBrakeTimePenalty( 60 )
	TrainBrakesControllerEmergencyBrakeTimePenalty( 60 )
	EngineBrakesControllerFullServicePressureDrop( 26 )
	TrainBrakesControllerFullServicePressureDrop( 26 )


	BrakesEngineBrakeType( "Air_single_pipe"  )
	BrakesTrainBrakeType( "Air_single_pipe" )
        BrakesEngineControllers( "Independent, Train," )
        
        EngineBrakesControllerDirectControlExponent( 1 )

	MaxDieselLevel ( 800gal )
	DieselUsedPerHourAtMaxPower ( 7gal )
	DieselUsedPerHourAtIdle ( 2gal )
	
	DieselEngineIdleRPM( 275 )
	DieselEngineMaxRPM( 1000 )
	DieselEngineSpeedOfMaxTractiveEffort( 17.3mph )        
        DieselEngineMaxRPMChangeRate( 40 )

	DoesHornTriggerBell( 0 )

	EmergencyStopMonitor(
    		MonitoringDeviceMonitorTimeLimit( 0 )
    		MonitoringDeviceAlarmTimeLimit( 0 )
    		MonitoringDevicePenaltyTimeLimit( 0 )
    		MonitoringDeviceCriticalLevel( 0 )
    		MonitoringDeviceResetLevel( 0 )
    		MonitoringDeviceAppliesFullBrake( 0 )
    		MonitoringDeviceAppliesEmergencyBrake( 1 )
    		MonitoringDeviceAppliesCutsPower( 0 )
    		MonitoringDeviceAppliesShutsDownEngine( 0 )
    		)

	AWSMonitor(
		MonitoringDeviceMonitorTimeLimit( -1 )
		MonitoringDeviceAlarmTimeLimit( 5 )
		MonitoringDevicePenaltyTimeLimit( 0 )
		MonitoringDeviceCriticalLevel( 0 )
		MonitoringDeviceResetLevel( 0 )
		MonitoringDeviceAppliesFullBrake( 0 )
		MonitoringDeviceAppliesEmergencyBrake( 1 )
		MonitoringDeviceAppliesCutsPower( 0 )
		MonitoringDeviceAppliesShutsDownEngine( 0 )
		)
	
	EngineVariables( 800 )
			
        EngineControllers (
            Throttle ( 0 1 0.125 0 
                NumNotches ( 9
                    Notch ( 0       0 Dummy )
                    Notch ( 0.125   0 Dummy )
                    Notch ( 0.25    0 Dummy )
                    Notch ( 0.375   0 Dummy )
                    Notch ( 0.5     0 Dummy )
                    Notch ( 0.625   0 Dummy )
                    Notch ( 0.75    0 Dummy )
                    Notch ( 0.875   0 Dummy )
                    Notch ( 1       0 Dummy )
                )
            )
            Brake_Engine ( 0 1 0.0125 0 
                NumNotches ( 1
                    Notch( 0  1 Dummy )
                )
            )
            Brake_Train ( 0 1 0.0125 0.65 
                NumNotches ( 5
                    Notch( 0    0 TrainBrakesControllerReleaseStart )
                    Notch( 0.3  1 TrainBrakesControllerGraduatedSelfLapLimitedHoldingStart )
                    Notch( 0.85 0 TrainBrakesControllerSuppressionStart )
                    Notch( 0.9  0 TrainBrakesControllerContinuousServiceStart )
                    Notch( 0.95 0 TrainBrakesControllerEmergencyStart )
                )
           
            )
            DirControl ( -1 0 1 1 )
            BellToggle( 0 1 0 )
            AWS ( 0 1 0 )
            Sanding ( 0 1 0 )
            Horn ( 0 1 0 )
            Wipers ( 0 1 0 )
            EmergencyStopResetToggle( 0 1 0 )
            EmergencyStopToggle( 0 1 0 )
            Vigilance ( 0 1 0 )
            Headlights ( 0 0.25 1 0 )
            BailOffButton( 0 1 0 )
        )
          
    	Sound ( "..\\..\\GP38\\SOUND\\gp38cab.sms" )

    	Name ("ALCO ATSF SLUG")
    	Description (
	"This slug is a cut down RS3 diesel with the cab and diesel removed. "+
	"A slug allows increased low speed tractive effort with the single engine operating at an efficient RPM. \n\n"+
	"American Locomotive Company  RS-2/3\n\n"+
	"Locomotive type: Diesel-Electric\n\n"+
	"Power source: lead diesel \n\n"+
	"Power: 1,500 hp\n\n"+
	"Max. speed: 65 mph (115 km/h)\n\n"+
	"Gear ratio: 74:18\n\n"+
	"Traction motors: Four model D67 DC, series wound, axle-hung\n\n"+
	"Wheel configuration: Eight 40-in (15.75 cm), tapered tread in B-B configuration (two sets of two "+
	"driven axles)\n\n"+
	"Height: 14 ft. 5 in. (4.42 m)\n\n"+
	"Weight: 124 U.S. tons (112.49 metric tons)\n\n"+
	"Length: 55 ft. 5.75 in. (15.53 m)\n\n"+
	"Width: 10 ft. 0 in. (3.09 m)"
    	)
 
)

All seems rather excessive, but it was posted in 2001.

I still have trouble accepting that ORTS would need a 0 hp engine to provide MaxForce ( 250kN ). How can that logically be? But I do think that there should be friction/mass/etc in the .eng file. I am curious to see what happens when only a slug is at the head of a consist, put a fake cab, and you can drive it?!?! Not too prototypical. I guess I will have to find some compromise.

Anyways, kinda moot, that distributed power from a diesel engine cannot be "sent" to a slug. Since slugs are rather few and far between, some hard lobbying would be needed to get distributed implemented as an upgrade to ORTS.

Any other ideas?

Thanks,
Steve

[eric]

It's what I'd call a black swan or an edge case in a normal development plan, but that doesn't necessarily mean impossible if you can find someone inclined to code for it. We've had lots of edge cases picked up by ORTS developers while normal/necessary task cards remained untouched.