[gpz]

copperpen, on 25 April 2014 - 02:00 PM, said:

Fcalc certainly does take into account the difference between different types of car, however, you must accept that Fcalc was developed to generate friction figures for MSTS and therefore the output will definitely be off by a certain amount.

I have never questioned that, moreover this is the primary reason I am proposing we could do it, at least for the "C" formula's leading/trailing property, better by multiplying it directly in OpenRails.

copperpen, on 25 April 2014 - 02:00 PM, said:

If you can develop in ingame method of applying these figures which then allows my test train to match a proven friction curve I will be convinced that what you propose is right. Until then I remain firmly in the ORTSDavis camp.

I'm not telling you should give up the fine-tuning. I'm just telling the ORTSDavis method is not for general use, we must develop a more automatic calculation, even if it will be at first a bit worse than the fine-tuned ORTSDavis method, while still be much better than the original MSTS way. Also we must forget about advertising a usage of a 3rd-party program to find out essential values of simulation, while it is perfectly possible to do the calculation ourselves too. I understand that the current state is enough for you, which is fine, and I fully appreciate the work you did in integrating the Davis formula into friction calculation. But it is not enough for OpenRails, we have to move on, to make this intermediate step of calculating A-B-C factors unnecessary for the "more simple" players and content developers.

steamer_ctn, on 25 April 2014 - 10:36 PM, said:

i) There are over 30 Davis equations quoted in the FCalc documentation - so these would need to be ultimately integrated into OR. Do they cover all the necessary combinations?

ii) As you have rightly suggested some means of distinguishing between the different vehicles types would be needed. - it would also be necessary to distinguish between different types of freight cars

iii) Is PassengerCapacity() parameter used universally in definition of railcars? If not, it could lead to misrepresentation of some railcars.

iv) As you have suggested some thought will need to be given to the variation of C factor in different circumstances.

I) We don't need to combine them. There are only max. 4-5 equations for each factor. And as a first step we don't need to cover everything to the finest details. Calculating A-B-C automatically will still be better than the original MSTS-style friction calculation.

II) Yes, I agree, we should add a wag option for this in the future. It is better asking players/content developers to define car type than asking to define ORTSDavis values.

III) It is used for the standard stock, but it cannot be guaranteed it is used for all community addons, of course. In this case it will lead to misinterpretation, yes. We have to ask from the players/content developers to add it if missing, and it is still better than asking to add ORTSDavis values.

By calculating ABC values automatically we don't exclude any possibility of using a different form of Davis equation, I think. And further research is always appreciated! :)

[jorgen]

steamer_ctn, on 25 April 2014 - 10:47 PM, said:

Hi Jorgen,
If you are NOT using the Davis values, and instead you are using the above "MSTS" values then the Bearing type, etc will NOT have any effect. See this thread.

If you are using the MSTS values, then nothing should have changed from OR 0.9. The bearing type is "embedded" in the FCalc calculations, refer to the FCalc documentation.

Thanks

Hi Again Peter
Now I think how it was supposed to work this function with Davis formula and starting friction.
February Fix 1978 Updated friction model to accept Davis values from ENG file, and made some small adjustments to the steam model.

If you don't change anything in Eng/Wag files should it work as OR 0.9 (original MSTS)
This would solve my problem to change all the old wag / eng files to get the wagons
to roll.

I have seen today that the locomotives operate properly right (eng.file). (Tested some engine)
The locomotives get not the large starting friction as the wagons get.

So my hypothesis is that Eng files work as intended
But not the wagons (wag files)
The wagons get solid bearings (orginal MSTS values)

To get normal values ​​of starting friction on wagons now you have to
put this line in the wag file
ORTSBearingType (Low)

Link1

Link2

[Matej Pacha]

Sorry for jumping into your discussion, but:
1) I disagree with any kind of comparison between weight and power like

Quote

Long trains with low hp/ton
http://youtu.be/n8uL3OkT_vM (three engine 140 loades coal wagon 21000 ton train) (0,62hp/ton)
http://youtu.be/aQimgGr4KKo (two engine 120 loaded grain wagons about 13000-14000 ton) (0,62hp/ton)

The friction is overcommed by tractive force, not by a power. Higher power results to higher possible speed. Even one 1000 hp locomotive can move 10000 ton train if the force can be 300 kN and higher.
2) The present 5mph (or any other) speed limit for starting friction resistance is a huge simplification. In real world the starting friction fades out after one or two wheel revolutions, as the lubricant spreads over the bearing. I hope we can figure something out during summer holidays.
3) Any discussion on the Davis formula accuracy has no sense to me - ORTS has no wind calculation, hence 20% difference is more than ok. However, to build up a precise friction model, we would need to have the air flow model and calculate it for every train set. That is not possible to do in real time.

Cheers,

Matej

[steamer_ctn]

Hi Jorgen,

jorgen, on 26 April 2014 - 01:49 AM, said:

I use MSTS values
Friction 580N/m/s -0.10 1.7mph 4.201N/m/s 1 -1rad/s 0 1 )
But in test 2 to 4 i add this line ORTSBearingType ( Friction roller Low )

Today i did test with Davis values , have rewritten my post yesterday Link
The text from link
Here was the original Msts values
Friction 580N/m/s -0.10 1.7mph 4.201N/m/s
5.1N/rad/s 1 -1rad/s 0 1 )
ORTSBearingType (Low)
-----------------------------------------------------
Then I replaced it with Davis values
ORTSDavis_A (188.165)
ORTSDavis_B (2.49802)
ORTSDavis_C (0.045)
ORTSBearingType (Low)

The results up to 5 Mph was same, but the difference were then the train come up to 5 mph.
If using (MSTS values) the friction were 580 Newton
Using (Davis values standard freight) the friction were 188 Newton.

Where did you get your Davis figures from?

Based upon your wag files, and using Fcalc I get the ones shown in the attached screenshot below.

I suspect that you have used the "imperial" version of the FCalc Davis figures (from the spreadsheet). This would explain the significant difference in the values. Is this correct?

jorgen, on 26 April 2014 - 10:01 AM, said:

If you don't change anything in Eng/Wag files should it work as OR 0.9 (original MSTS)
This would solve my problem to change all the old wag / eng files to get the wagons
to roll.

Correct

jorgen, on 26 April 2014 - 10:01 AM, said:

I have seen today that the locomotives operate properly right (eng.file). (Tested some engine)
The locomotives get not the large starting friction as the wagons get.

So my hypothesis is that Eng files work as intended
But not the wagons (wag files)
The wagons get solid bearings (orginal MSTS values)

To get normal values ​​of starting friction on wagons now you have to
put this line in the wag file
ORTSBearingType (Low)

There shouldn't be any difference between wagons and locomotives.

It will depend upon how the MSTS OR Davis values have been defined.

Cheers

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[steamer_ctn]

steamer_ctn, on 13 April 2014 - 12:28 AM, said:

jorgen, on 12 April 2014 - 12:37 PM, said:

Have done a downhill test with roller bearing 105 wagon 50 ton each (5500ton).
It is 5,5 per thousand downhill. I release the brake and the train don't to start to roll.
Is that behaviour normal? I asking train engineer here.
I do not know right now in OR what slope it takes to train to roll. (maybe 8)

I agree, they will probably struggle to start on a hill (depending upon the gradient). Other forms of resistance, such as curve, etc will also impact these calculations.

I have done some further testing on this, and it appears that trains will roll down a hill under their own weight in OR. (by simply releasing the brake and NOT applying any throttle)

To do so, the total train gravitational forces need to exceed the total frictional forces of the train (can be viewed in the Force HUD - Motive force should equal 0). The steeper the slope the higher the gravitational forces. In addition, if the train is stopped on a curve, then the curve resistance would also need to be overcome by the gravitational forces.

Naturally friction (or solid bearings) will have more starting resistance, so it will hold a greater load on the slope before the train starts to move. A low torque bearing train will tend to move off easier under its own weight.

Is this the general experience of others?

Cheers

[jorgen]

steamer_ctn, on 26 April 2014 - 08:45 PM, said:

Hi Jorgen,
Where did you get your Davis figures from?
Based upon your wag files, and using Fcalc I get the ones shown in the attached screenshot below.
I suspect that you have used the "imperial" version of the FCalc Davis figures (from the spreadsheet). This would explain the significant difference in the values. Is this correct?

There shouldn't be any difference between wagons and locomotives.
It will depend upon how the MSTS OR Davis values have been defined.

Hi Peter
My fcalc from 2005 had no values for davis values (downloaded from train sim com)
so i use spread sheet (i don't know if that imperial). (attached xls file)
I see now that it was pounds instead of newtons. 4.44822162 * Pound = newton

But I could have chosen any values​​, because I was just interested in was how the train behaves from 0-5 mph.
Actually I am interested only up to 0.5 mph then will davis values ​​take over (solution I hope soon).

I have seen today that even some wagons are right.
But some wagons becomes wrong.
In my case, most wagons get solid bearings
See picture on the mixed train, some wagons have 1115 Newton (right)
While most wagons have 6963 Newton ( wrong=solid bearings )
I have not changes this wagons at all (MSTS orginal)
Picture under is same train but in Or 0,9

You can look at the tread yesterday when I sent two wag files to you.
This wag file without the (orts bearing) does not go well for me. It becomes solid bearing on the wagon.
Then it is how it is written in the wag file that makes that sometimes it becomes OR 0.9
and sometimes a wagon with Solid Bearings.
. , Space, tab, I do not know

Bye Jorgen

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Attached File(s)

•  FCalc 2.0 COFC.xls (72.5K)
  Number of downloads: 278

[steamer_ctn]

Hi Jorgen,

jorgen, on 26 April 2014 - 09:56 PM, said:

My fcalc from 2005 had no values for davis values (downloaded from train sim com)

Is it Fcalc2? Have a look at the Help TAB (About).

If it isn't go and download a more recent version. Then look under the view options to make Davis values visible.

jorgen, on 26 April 2014 - 09:56 PM, said:

so i use spread cheat (i don't know if that imperial). (attached xls file)
I see now that it was pounds instead of newtons. 4.44822162 * Pound = newton

Ok, you could specify the units are in imperial. See my comments in previous posts.

jorgen, on 26 April 2014 - 09:56 PM, said:

But I could have chosen any values​​, because I was just interested in was how the train behaves from 0-5 mph.
Actually I am interested only up to 0.5 mph then will davis values ​​take over (solution I hope soon).

The Davis formulas only work > 5mph. The Davis values are not used directly < 5mph.

jorgen, on 26 April 2014 - 09:56 PM, said:

I have seen today that even some wagons are right.
But some wagons becomes wrong.
In my case, most wagons get solid bearings
See picture on the mixed train, some wagons have 1115 Newton (right)
While most wagons have 6963 Newton ( wrong=solid bearings )
I have not changes this wagons at all (MSTS orginal)
Picture under is same train but in Or 0,9

This will depend how the MSTS or Davis values are set in the WAG file.

jorgen, on 26 April 2014 - 09:56 PM, said:

You can look at the tread yesterday when I sent two wag files to you.
This wag file without the (orts bearing) does not go well for me. It becomes solid bearing on the wagon.
Then it is how it is written in the wag file that makes that sometimes it becomes OR 0.9
and sometimes a wagon with Solid Bearings.
. , Space, tab, I do not know

I couldn't see any difference between the files, so they should have been treated the same.

[jorgen]

Yes it is Fcalc 2,0,2139,34987
But i use spread sheet. See it yourself, that file was attach. I don't know.
But the values was wrong. it was in pound instead in Newton. I saw it now.

There was no davis formula at all. The files are from 2000-2005.
It is only 1 wag files i tested Davis formula at all (i have 800 wag files)
as I showed yesterday.
--------------------------------------------------
Davis formula ex.
ORTSDavis_A (504.165)
ORTSDavis_B (8.49802)
ORTSDavis_C (0.145)
ORTSBearingType (Friction Roller Low)
--------------------------------------------------------------------

Yes it was difference in the wag files, but I send it again but only one file now.
This wag wagon get Solid bearings. Use this in train and test yourself.

Take your carriage you replace this wag.file
Take a unique name on the wagon for a Consist and testing of the train.

Is it just me having these problems on many of the cars.
Can people try this.
1: First use version x 2194
2: Select a train that has the original values ​​(No davis formala att all) in the wag files.
3: Start Or 2194 with the actual train. Stand still with the train. (test multiple trains)
4: press F5 and shift + F5 to bring up the Force information (se picture in thread above)
5: Check in Friction box
6: Is the value on wagons of around 500-2000 normal, but it is 3000-10000 you having solid bearings in your cars.
The heavier the wagon is the higher the value of friction value (the solid bearing)
PS engine have higher friction than wagons usually. DS

Write here and announce the answer.

[steamer_ctn]

jorgen, on 26 April 2014 - 11:55 PM, said:

--------------------------------------------------
Davis formula ex.
ORTSDavis_A (504.165)
ORTSDavis_B (8.49802)
ORTSDavis_C (0.145)
ORTSBearingType (Friction Roller Low)
--------------------------------------------------------------------

All three bearing type parameters in the one statement.

It should only be one of the following:

ORTSBearingType ( Roller )

OR

ORTSBearingType ( Friction )

OR

ORTSBearingType ( Low )

[jorgen]

This problem is that some wagons may solid bearings do not seem easily solved.
In the pictures below you can see how weird it gets.

The same eng and wag file makes some wagons become normal and some wagons have solid bearings.
I think we can rule out that it is wrong to wag file.

Because it is right in the first wagon but second wagon and back problems begin.
But OR 2194 misinterpret the information in any way.

If you have unique wagons the whole train it will be probably right.
But if you have several identical wagons one after the other resulting problems it seems.

It seems complex problem in each case.
Here, one might test more to see what the problem are.
--------------------------------------------------------------------
This problem haven't we in Or 0,9

If you find no solution to the problem maybe you should introduce
Default (low) instead of Solid Bearings.
Now we can put in line ORTSBearingType (Low) to solve the problem.

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