[NickonWheels]

Hmm... I do understand ORTS diesel engine parameters and I´m indeed able to figure out all the necessary values in them; I just tried what happens when MaxDieselLevel is missing... Weird outcome, don´t know where the 5000 comes from, but that´s what this line is for.

You maybe meant to put MaxDieselLevel into the include file, which I would never do because for example not all SD40-2s have the same fuel capacity. The other lines like smoke magnitude can be deleted though...

[Lamplighter]

I don't attach much importance to include files. The .eng and .wag settings files are plain text. They take up no space. For better clarity I use all parameters together.

[steamer_ctn]

NickonWheels, on 18 December 2019 - 03:33 AM, said:

The only files I can offer you are about the London & Port Stanley diesels (which are the same files in content), others were modified with my huge collection of include files. Gerry made 176 files while I combined some and made new ones like the RSC-24 the new model by Pual Charland, having 164 files...
CANG12v1.eng

I have added some code to the latest unstable version to address this problem (I think). Basically it was an issue with the power and force values not being "correctly" initialised for the locomotive. Hopefully it should now work in the unstable version.

I think that I have identified some other issues with diesel configurations that I want to investigate further once I have some test models configured by some testers who are assisting me.

In regard to INC file, they should be carefully used, as there is a potential issue when BASIC and ADVANCED configurations are used within the ENG files. See this post for the relevant comments on data sequencing in OR. Incorrect sequencing of mixed configurations may cause errors.

[NickonWheels]

Thanks, Peter

Driving diesels with engine tab and traction curves for a while now I witnessed that with such engines the file MaxVelocity does´nt work properly anymore (not just in X1.3.1-107 version). My CN Ruel Sub engines got at least 115mph but MaxVelocity says 70mph as with most rather modern US diesels. There must be some code bug causing the traction curves to override the fuction of this crucial line.

Yes I tried and observed many ORTS shortcomings, which many of you might never had noticed before.
Nick

[steamer_ctn]

NickonWheels, on 20 December 2019 - 02:10 AM, said:

Driving diesels with engine tab and traction curves for a while now I witnessed that with such engines the file MaxVelocity does´nt work properly anymore (not just in X1.3.1-107 version). My CN Ruel Sub engines got at least 115mph but MaxVelocity says 70mph as with most rather modern US diesels. There must be some code bug causing the traction curves to override the fuction of this crucial line.

Yes I tried and observed many ORTS shortcomings, which many of you might never had noticed before.

As far as I can see in the code, MaxVelocity sets the motive force to zero for locomotives without traction curves defined. However I don't believe that this is the case in real life.

A properly defined traction curve would take the max velocity into account.

As suggested I won't be doing any more significant code changes until I have some well defined test models available to me that I can use to test performances against well defined test reports.

Thanks

[edwardk]

Are we certain that MaxVelocity() is being zeroed out? In the code, MaxVelocity() is read into a new variable called MaxSpeedMps. I was unable to locate a line that would zero out MaxSpeedMps. It may be possible that a new set of calculations is not using MaxSpeedMps.

[edwardk]

Check this out to see if this is the reason why the MaxVelocity() source is not working. Keep in mind that MaxSpeedMps is now representing MaxVelocity()

Peter, I know you saw this as well, but in my mind the two if statements using MaxSpeedMps are contradicting each other. You notice the original statement that is commented out where maxForceN is set to 0, but this statement is now used after a new calculation.

if (TractiveForceCurves == null)
                {
                    float maxForceN = MaxForceN * t * (1 - PowerReduction);
                    float maxPowerW = MaxPowerW * t * t * (1 - PowerReduction);

                    if (maxForceN * AbsWheelSpeedMpS > maxPowerW)
                        maxForceN = maxPowerW / AbsWheelSpeedMpS;
                    //if (AbsSpeedMpS > MaxSpeedMpS)
                    //    maxForceN = 0;
                    if (AbsSpeedMpS > MaxSpeedMpS - 0.05f)
                        maxForceN = 20 * (MaxSpeedMpS - AbsSpeedMpS) * maxForceN;
                    if (AbsSpeedMpS > (MaxSpeedMpS))
                        maxForceN = 0;
                    MotiveForceN = maxForceN;
                }

[steamer_ctn]

edwardk, on 21 December 2019 - 10:18 AM, said:

Peter, I know you saw this as well, but in my mind the two if statements using MaxSpeedMps are contradicting each other. You notice the original statement that is commented out where maxForceN is set to 0, but this statement is now used after a new calculation.

That is why I made the comment that I thought Motive Force was zeroed once the MaxVelocity had been exceeded. However it would need to be tested and confirmed.

[steamer_ctn]

As suggested earlier on in this thread, I wish to investigate aspects of the diesel locomotive code in some more detail. To do this I have created a test model, for comparison of code change results.

The locomotive selected is a BR unit which was the subject of a detailed test report, and this can be used to accurately configure the model, as well as compare the OR outcomes.

The model consists of a locomotive ( BR D16/2 #10203 ) and a set of cars ( Mark1 ), and the locomotive is set up with two configurations, ADVANCED and BASIC. For a general description of the difference between BASIC and ADVANCED configurations, refer to this page. As a demonstration, I have configured the BASIC model as a minimalistic version which only has enough parameters to get the model running. The ADVANCED version has all the relevant power/force tables modeled from the test report. (Note, these files should be considered a work in progress)

As part of the testing, it will be interesting to see the difference in performance between the BASIC and ADVANCED versions, and thus it is suggested that anybody wishing to run any tests should read the referenced test report to get an understanding of the locomotive and its performance in real life. One test might be to use the CTN test route, and run the train up the 1 in 80 gradient, based upon graph 11 in the report, a steady state speed of approx 30 mph should be achievable with a load of 286 tons uk.

This model only has a single prime mover, so I am considering also configuring a unit which also has a test report, and has two prime movers (BR Deltic) to see how it performs in OR.

[Gehe]

Hi All,

beside the issue discussed above I found a changed behaviour related to diesel performance in the newest OR version
27th December, X1.3.1-108-g85be7602 which I would like to add to this topic.

For diesel locos not using tractive force tables the motive force and power are derived from the max power and max force statements in the eng files.
In this new version it looks like that there is a new kind of power reduction. If you have 100% throttle you get just 78.4% of the max power to the wheels.
You can see this factor of 78.4% also in the extended F5 HUD (locomotive view) as a load factor.

I would like to know what is reason behind this new behaviour? There was no change in my eng files.

I believe this has nothing to do with the reduction factor of 0.98 which is used in OR generally for diesels;
also the model used for warming up of the traction motors should not be of any significant effect here since the locos were "cold".


Best Regards
Gehe

[NickonWheels]

I noticed this before, however I´m using traction tables for all new .eng files to modify (if it´s worthwhile).

[Csantucci]

Gehe, on 29 December 2019 - 05:37 AM, said:

Hi All,

beside the issue discussed above I found a changed behaviour related to diesel performance in the newest OR version
27th December, X1.3.1-108-g85be7602 which I would like to add to this topic.

For diesel locos not using tractive force tables the motive force and power are derived from the max power and max force statements in the eng files.
In this new version it looks like that there is a new kind of power reduction. If you have 100% throttle you get just 78.4% of the max power to the wheels.
You can see this factor of 78.4% also in the extended F5 HUD (locomotive view) as a load factor.

I would like to know what is reason behind this new behaviour? There was no change in my eng files.

I believe this has nothing to do with the reduction factor of 0.98 which is used in OR generally for diesels;
also the model used for warming up of the traction motors should not be of any significant effect here since the locos were "cold".


Best Regards
Gehe

i am a bit frightened of these changes in the way basic, original MSTS parameters are used. There are plenty of engines who have been modeled with their .eng parameters, who are used in activites that are tailored accordingly to the performance of such engines. I don't see it is advisable to change the performance of such engines after years of usage of them in OR.

[steamer_ctn]

Gehe, on 29 December 2019 - 05:37 AM, said:

beside the issue discussed above I found a changed behaviour related to diesel performance in the newest OR version
27th December, X1.3.1-108-g85be7602 which I would like to add to this topic.

I am unaware of any significant code changes in this area since v1.3.

Gehe, on 29 December 2019 - 05:37 AM, said:

If you have 100% throttle you get just 78.4% of the max power to the wheels.
You can see this factor of 78.4% also in the extended F5 HUD (locomotive view) as a load factor.

I can't comment on this specific value without seeing the specific locomotive, however I will make the following generic comments.

The code in effect defines Load% = Actual Output Power (Motive Force) / Diesel Prime Mover Output Power

The Motive Force value will vary depending upon the load on the locomotive, so light engines will not require as much motive force to move them, whereas heavily loaded locomotives will require more motive force to move them.

The Diesel Prime Mover Output power will be as defined in the ENG file.

So to illustrate, a couple of examples (which can be confirmed by testing).

In the case of legacy (MSTS defined) locomotives the Prime Mover output power is set equal to the Rail Power, as no other information exists in the ENG file to discriminate for OR.

Thus using the default Dash9 as an example, the Prime Mover power is set to 4400hp, and the maximum power to rail is also set to this same value (via the MaxPower parameter).

Hence, if the full amount of motive power is required to move the locomotive, then it is possible to see Load% up around 90%+. As far as I am aware, this has not changed between v1.3 and the most current unstable version, and can be verified by running an appropriate default Dash9 consist in both versions and comparing the results.

In the case of more recently configured locomotives, it will be dependent upon how the locomotive has been configured and what powers have been assigned to the above Powers in the ENG file. For example, if the prime mover output power has been set realistically, then it will always be higher then the maximum possible motive force that can be achieved, and thus lower % figures will be obtained.

For example, with my test locomotive the prime mover output power is 1888hp, whereas the maximum power to rail is 1560hp. Thus the maximum load% will only ever be about 82%, whereas it is more likely to be less then this value as the locomotive may not be producing maximum motive force (maximum power output). So a value of around 78% could in theory be obtained without too much trouble.

As suggested I don't believe any code changes will have affected this value since v1.3, and it is more a outcome of how the ENG file has been defined.

Remembering that there are differences between how a BASIC and ADVANCED locomotive is defined (ie different information Tables, etc).

Gehe, on 29 December 2019 - 05:37 AM, said:

I would like to know what is reason behind this new behaviour? There was no change in my eng files.

Can you provide me with an example ENG file that demonstrates the concern that you are raising?


Moving forward.
As suggested my I wanted to review some of the operation of the diesel code, and thus two questions come to mind:
i) What is this value used by the user for within the simulation?
ii) Given that some people have suggested that it is actually an efficiency value, what efficiency should it be expressing?

Thanks

[R H Steele]

steamer_ctn, on 29 December 2019 - 02:37 PM, said:

Moving forward.
As suggested my I wanted to review some of the operation of the diesel code, and thus two questions come to mind:
i) What is this value used by the user for within the simulation?
ii) Given that some people have suggested that it is actually an efficiency value, what efficiency should it be expressing?

Thanks

That's one of the concepts I've had the most trouble grasping. Thanks to help from some patient ET members I think I've learned. I'll go a little out on a limb: when Bob Boudoin refers to the efficiency of a diesel locomotive he is referring to the accumulated losses through the "transmission system". RailHP/TractionHP equals locomotive efficiency ( 85% for example ). Traction HP being the input hp to the generator/alternator. Losses from the generator/alternator, traction motors and gearing ( transmission system ) are accounted for in this scheme.
However, to confuse the issue, I've also found legacy engine files referring to the efficiency as the total sum of losses from BHP ( MaximalPower in OR ) to RailHP. Moreover, some legacy engine files refer to the MaxPower value as "Traction HP". (is that a confusion with RailHP?)
I also thought there was some discrepancy in how the HUD expressed diesel locomotive efficiency. I'm not so sure about that opinion anymore -- at present I think the Load% percentage expressed in the HUD is accurate ( it may need some fine tuning ). I do know, from emails with Bob Boudoin that he has reservations about how OR handles diesel locomotives with AC traction. My understanding is that OR was built to model DC traction and does a good job...but it falls short with AC traction and that may have some bearing on the Load% expressed in the HUD. It may be beneficial for someone with more understanding of the issues than myself contact Bob and get his views on the subject.

[steamer_ctn]

I have uploaded another test locomotive.

This one is somewhat interesting as it has two diesel prime movers providing input to the generators. Looking quickly at it I have tried turning the engine off and back on again, but it doesn't seem to work. I am wondering if this has broken the OR model?

I would be interested to see if anybody has a working two engine model for comparison.