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PostPosted: Wed May 16, 2018 12:54 am 
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A chunk of the time it takes me to code and compile GRF's is tweaking the Tractive effort coefficient values which is rather annoying.

Is there anyway in NML to set the TE by hand rather then rely on the coefficient?

For example, rather then say
Code:
tractive_effort_coefficient : 0.22 // 280 kN target 


it would be nice if i could just say, put that number in directly

Code:
tractive_effort : 280 kN


I mean the other numbers for a vehicles specs/performance like power, speed, and weight are set
Code:
speed : 120 km/h,
power : 1550 HP,
weight : 143 tons,

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PostPosted: Wed May 16, 2018 6:26 am 
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No, because TE is a calculation from the co-efficient and the vehicle weight.

Weight of the vehicle can change during gameplay (for example, an engine with cargo capacity, or a bus), this changes the calculated TE value.

If you're working on setting real-life TE values I wouldn't worry about being super accurate:
- TE figures are often 'nominal', i.e. calculated based on weight on the drivers, rather than measured on a train
- actual measured TE varied between different engines of the same class
- actual TE varies as the engine uses up fuel, water etc
- actual TE varies with rail conditions
- lots of the figures come from Wikipedia, and train fans in forums call it Liarpedia but eh :twisted:

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PostPosted: Wed May 16, 2018 7:04 am 
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NekoMaster wrote:
A chunk of the time it takes me to code and compile GRF's is tweaking the Tractive effort coefficient values which is rather annoying.


If your tracking table is a spreadsheet, just add a TE coefficient column calculated from the nominal TE and weight. No tweaking required.

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PostPosted: Wed May 16, 2018 7:47 am 
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NekoMaster wrote:
Is there anyway to just set Tractive Effort (rather then a Coefficient?)

m4nfo allows to set tractive effort in kN/kp/lbf directly:

Code:
definevehicle(_BR75, "BR 75 (ex wü. T5)",
   lifecycle(1-1-1912, 1932, 1963)
[...]
   speed(75 km/h)
   power(880 PS)
   weight(71 t)
   effort(101 kN)
   price(68'750 RM) // DM == RM
   runningcost(7'563 RM)
)


andythenorth wrote:
Weight of the vehicle can change during gameplay (for example, an engine with cargo capacity, or a bus), this changes the calculated TE value.

If you're working on setting real-life TE values I wouldn't worry about being super accurate:
- TE figures are often 'nominal', i.e. calculated based on weight on the drivers, rather than measured on a train
- actual measured TE varied between different engines of the same class
- actual TE varies as the engine uses up fuel, water etc
- actual TE varies with rail conditions
- lots of the figures come from Wikipedia, [...]

For locomotives, tractive effort is as well defined as is power. Even for MUs (where tractive effort isn´t really meaningful, but acceleration is the most important figure), it would be meaningful, since additional weight by load (passengers) would be negligible.

You have a point here, insofar that actual TE varies (heavily) with rail condition. But given the fact, that there´s always dry and sunny weather in TTD, this is irrelevant.

regards
Michael

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PostPosted: Wed May 16, 2018 7:54 am 
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For example, 2cc in nml spreadsheet contain handy calculation of TE coefficient based on vehicle weight and TE, see column O
https://docs.google.com/spreadsheets/d/ ... =259018472

BTW, I noticed, that 2cc set and some others sets have wrong steam locomotive weights - often there is locomotive weight without tender.

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PostPosted: Wed May 16, 2018 8:35 am 
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michael blunck wrote:
m4nfo allows to set tractive effort in kN/kp/lbf directly:

Presumably that's just calculating the coefficient from the vehicle weight and desired TE? Nice.

I agree that for most trains, the weight of any payload isn't a significant factor. It's more relevant for road vehicles, e.g. a freight truck with tare weight 20t and payload 20t ;)

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PostPosted: Wed May 16, 2018 9:54 am 
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andythenorth wrote:
mb wrote:
m4nfo allows to set tractive effort in kN/kp/lbf directly:

Presumably that's just calculating the coefficient from the vehicle weight and desired TE? Nice.

Yes. In conseqence using a TE callback, vehicle weight has to be given as well:

Code:
def(2) veh_railtype(
   seteffort(240 kN, 15 t) if(FRNR) // set TE for rackrail track
   cbfail() else
)

Since, due to distributed source files, vehicle weight isn´t always accessible.

andythenorth wrote:
I agree that for most trains, the weight of any payload isn't a significant factor. It's more relevant for road vehicles, e.g. a freight truck with tare weight 20t and payload 20t

You see, I´m a train man.

regards
Michael

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PostPosted: Wed May 16, 2018 11:22 am 
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I do have the Tractive Effort listed in my Data Sheets/Spread Sheets but I still have to guess and tweak the coefficient in Code and see if that gets close enough to what i need.

Also while TE can change IRL with weight, wear, track conditions and weather, in OpenTTD TE doesnt seem to change (at least in the vehicle info window). LIke someone said its pretty much a sunny summer all the time in OpenTTD except in the sub-arctic where theres snow (which can change if you have a variable snow line GRF like OpenGFX landscape)

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PostPosted: Wed May 16, 2018 11:41 am 
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Why do you need to guess, isn't it just effort/mass/10?

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PostPosted: Wed May 16, 2018 12:58 pm 
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peter1138 wrote:
isn't it just effort/mass/10?


For nfo it's TE / (weight * 9.8 ) * 255, as per the wiki. I'm not sure why the NML spec uses 10 instead of 9.8.

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PostPosted: Wed May 16, 2018 2:33 pm 
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PikkaBird wrote:
peter1138 wrote:
isn't it just effort/mass/10?

For nfo it's TE / (weight * 9.8 ) * 255, as per the wiki. I'm not sure why the NML spec uses 10 instead of 9.8.

The conventional standard value for gravitational acceleration is 9.80665 m/s². So, "10" might be just a simplification, same as "9.8" had been back in TTDPatch times.

regards
Michael

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PostPosted: Wed May 16, 2018 3:56 pm 
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Hehe, well it's 10 in OpenTTD's source too. Since 2006.

Edit: It's 9.8 now.

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