[edwardk]

steamer_ctn, on 30 December 2019 - 04:45 PM, said:

Thanks for raising this concern.

Can you point to the references suggesting that MaxPower should be equal to HP - Efficiency.



That is the main reason that I try to use test models that have a supporting railway test report.

Both of these models, as indicated, have had a BR test report done on them, so it is possible to find accurate information for the parameters, and test results that can be used to compare the models performance.

So give them a go and see what you think. (The ENG files may require further tweaking, or similarly the code may need some changes).

Although I did not mention MSTS, MaxPower() would have reflected the hp minus efficiency. When OR came out, people would have changed the hp parameter to the full hp.

Regarding physics, I am also including the period before you started making changes. When it comes to testing, how should this be done? When adding the basic parameters to SLI's Calfornia Zephyr, I noticed the overall train is on the weak side. The standard consist is made up of 2 locomotives(F40PH) and 11 cars. I am not sure how long a train of this type would be in real life, but I do find it is on the weak side which is why I brought up physics. The full hp for this locomotive is between 3000 and 3200hp. I am guessing the efficiency rating would be around 89% since these are older locomotives.

I will test with full hp to see how the train operates. The weight used for the cars appears to be normal.

[R H Steele]

edwardk, on 31 December 2019 - 06:09 PM, said:

The full hp for this locomotive is between 3000 and 3200hp. I am guessing the efficiency rating would be around 89% since these are older locomotives.

I will test with full hp to see how the train operates. The weight used for the cars appears to be normal.

I have Bhp at 3200-3300, TractionHP @ 3000 -- efficiency at 84% for DC traction which gives a Rail hp of 2520. AFAIK OR does not model the constant engine rpm of 893 while in hep mode.

[NickonWheels]

All these numbers are quite confusing. For modification of the engine include files I took the most often available information; for the SD40-2 it´s 3000 hp and using the traction curves max power at rail would be around 2935 hp, at least theoretically.

[steamer_ctn]

For those interested, I have run some tests with the DEE 10203 locomotive, and comparing it against the test report. From the test that I am doing, I am getting very good correlation with the test report, so it appears that OR can get a very realistic outcome if set up correctly.

I have made some minor changes to the ADVANCED ENG file (see attached).

The test is based upon the results on Graph 11 of the test report. I am running a 300 ton consist (even though strictly speaking a 286 ton consist is required) up the 1 in 80 gradient in the Coals to Newcastle test route. Graph 11 suggests that with 81% bhp, or a throttle setting of 704 rpm, I should increase in speed until I balance at a speed of 30mph. I am slightly under this speed if I use the 300 ton consist, and slightly over it if I use a modified consist with one less car (just less then 286 tons), so it appears to be a good match. EDIT: For testing you will need to disable wind resistance, as the wind during the tests were negligible.

The BASIC configuration will not achieve similar results at the moment, because the ENG file demonstrates a minimalist configuration, and the default RPM settings for the prime mover will not correlate to the require 704 rpm. So it will require some Prime Mover settings to added.

Based upon my research so far, I believe that the most accurate way of setting the diesel locomotive is to use the following specification information:

i) Maximum Force
ii) Max Continuous Force
iii) Speed of max continuous force.

Most of this information seems to be readily available on the INTERNET for most locomotives.

Attached File(s)

•  DEE_10203_or_adv.zip (6.58K)
  Number of downloads: 374

[R H Steele]

steamer_ctn, on 01 January 2020 - 09:35 PM, said:

Most of this information seems to be readily available on the INTERNET for most locomotives.

Peter, thank you for the tests, very much appreciated! The only caveat I can add applies to statement quoted...beware of internet sources...many are inaccurate and/or repeat inaccurate information.For the important values you suggested I recommend downloading all of Bob Boudoins most recent physics files...the values are very accurate.

[steamer_ctn]

R H Steele, on 02 January 2020 - 09:27 AM, said:

thank you for the tests, very much appreciated! The only caveat I can add applies to statement quoted...beware of internet sources...many are inaccurate and/or repeat inaccurate information.For the important values you suggested I recommend downloading all of Bob Boudoins most recent physics files...the values are very accurate.

Thanks for the feedback, and I agree that information on the INTERNET is not always correct.

The real points that I was trying to make were,

i) that were accurate force information was available, it would provide a more accurate calculation of the Rail Power (MaxPower) value then using the Rated Hp - an arbitrary efficiency value.

ii) the accuracy of OR's performance will naturally depend upon the accuracy of the information used to define the pieces of rolling stock.

[edwardk]

steamer_ctn, on 01 January 2020 - 09:35 PM, said:

For those interested, I have run some tests with the DEE 10203 locomotive, and comparing it against the test report. From the test that I am doing, I am getting very good correlation with the test report, so it appears that OR can get a very realistic outcome if set up correctly.

I have made some minor changes to the ADVANCED ENG file (see attached).

The test is based upon the results on Graph 11 of the test report. I am running a 300 ton consist (even though strictly speaking a 286 ton consist is required) up the 1 in 80 gradient in the Coals to Newcastle test route. Graph 11 suggests that with 81% bhp, or a throttle setting of 704 rpm, I should increase in speed until I balance at a speed of 30mph. I am slightly under this speed if I use the 300 ton consist, and slightly over it if I use a modified consist with one less car (just less then 286 tons), so it appears to be a good match. EDIT: For testing you will need to disable wind resistance, as the wind during the tests were negligible.

The BASIC configuration will not achieve similar results at the moment, because the ENG file demonstrates a minimalist configuration, and the default RPM settings for the prime mover will not correlate to the require 704 rpm. So it will require some Prime Mover settings to added.

Based upon my research so far, I believe that the most accurate way of setting the diesel locomotive is to use the following specification information:

i) Maximum Force
ii) Max Continuous Force
iii) Speed of max continuous force.

Most of this information seems to be readily available on the INTERNET for most locomotives.

I just want to confirm that the above items would have to be used when using the Basic configuration? The first two are already included, but the third will have to be added.

[steamer_ctn]

edwardk, on 02 January 2020 - 03:09 PM, said:

I just want to confirm that the above items would have to be used when using the Basic configuration? The first two are already included, but the third will have to be added.

I have attached the BASIC ENG file for the test locomotive which shows the information that is required.

It should be noted that as this configuration does not have the Prime Mover set up, so the throttle will need to be set to 68% to get the same effect as the ADVANCED version that shows an rpm value of 704 rpm.

The MaxPower value should also be calculated from ii) and iii) as follows:

HP = Cont Force * Speed / 375

[R H Steele]

steamer_ctn, on 02 January 2020 - 05:04 PM, said:

I have attached the BASIC ENG file for the test locomotive which shows the information that is required.

It should be noted that as this configuration does not have the Prime Mover set up, so the throttle will need to be set to 68% to get the same effect as the ADVANCED version that shows an rpm value of 704 rpm.

The MaxPower value should also be calculated from ii) and iii) as follows:

HP = Cont Force * Speed / 375

A question....the above equation assumes a 85% ( somewhere around there if I remember correctly ) efficiency in converting power output to tractive force....that's fine for locomotives in that immediate range -- not so accurate for modern AC traction locomotives with efficiencies above 85% and upwards to 96% or older locomotives with efficiencies less than 85%. Is this to be considered sufficient for the basic configuration? Does the code consider different efficiencies for the advanced configuration -- or -- is it assumed that ORTS tractive curves will be present in the advanced configuration that take efficiency into account. There have been numerous posts asking about an ORTS parameter for efficiency....could this be considered?
This paper has a formula that takes efficiency into account: (pages 10 and 11 )http://128.173.204.6..._resistance.pdf
Regards, Gerry http://www.elvastower.com/forums/public/style_emoticons/default/hi.gif thanks for all your time and effort, Peter.

[steamer_ctn]

R H Steele, on 02 January 2020 - 09:51 PM, said:

A question....the above equation assumes a 85% ( somewhere around there if I remember correctly ) efficiency in converting power output to tractive force.

Does it really? I was under the impression that the "375" was a constant to allow the use of imperial values rather then metric values, and as far as I am aware it did not include any allowance for efficiency "loss". I would need to do some more research to confirm this though.

R H Steele, on 02 January 2020 - 09:51 PM, said:

Does the code consider different efficiencies for the advanced configuration -- or -- is it assumed that ORTS tractive curves will be present in the advanced configuration that take efficiency into account. There have been numerous posts asking about an ORTS parameter for efficiency....could this be considered?This paper has a formula that takes efficiency into account: (pages 10 and 11 )http://128.173.204.6..._resistance.pdf

OR does not have any "built in" allowance for efficiencies. This however can be factored in by the user in terms of the settings they apply. It relies on the user to set powers and force figures correctly. The prime mover (engine) power and traction power curves are relatively independent of each other.

The formula quoted would only apply depending upon what power value is used as the reference value. For example, if the reference power is the Prime Mover rating, or output power then an efficiency value would need to be applied to allow for further power losses through the traction motors and transmission, etc.

However if the power used is the actual power applied to the rail, then it already has the efficiencies taken out, and therefore there are no more losses to be incurred.

My understanding is that the values for maxForce, and MaxContinuousForce are the forces applied directly to the rail (ie the final output by the locomotive), thus when this value is converted to a power value, no efficiency value is required as it is a straight power/force value conversion. That is why I am suggesting that these figures are better to use if they can be trusted. Normally the efficiency values are not published, and therefore they are mostly a "educated" guess, whereas the the tractive rail forces should be an actual factual reference.

At the moment if we have the same figures for an AC locomotive, then I would think that they should be able to be used in the same fashion (yet to be confirmed).