This discussion I would like to lead here is related to a thread started by imnew back in 2013 over in Scenario Creation. You can read that thread here:
viewtopic.php?f=8&t=9419
Since I last posted in that thread, I've been doing some pondering, studying, number crunching, and testing with locomotive across a variety of routes with different types of trains and my findings over the last year or so seem to indicate something about the power of diesel locomotives in Train Simulator 2016 that may not prove popular in light of recent offerings by DTG, DTM, and FanRailer's mods.
The question has been raised as to what unit of measure is the maxpower line in the loco's sim file. Most will probably say that this is horsepower. The original dev docs say it's kilowatts. There's evidence from DTG that older stock assumes kilowatts and then some newer stock assumes horsepower. DTM assumes it's horsepower. All of FanRailer's mods assume horsepower. My studying and testing thus far, however, concludes that the maxpower line is kilowatts.
The testing has been over a period of more than a year across Cajon Pass (including the modern version recently released in the steam workshop), Donner Pass, Marias Pass, Stevens Pass, Horseshoe Curve, Soldier Summit, and Sherman Hill. I've done everything from fast intermodal freights to heavy coal drags weighing in excess of 12,000 tons using a wide variety of motive power.
Let's take a look at some of the stock in question.
If you go to Donner Pass and open the Dash 9's simulation file, do a control-f search for maxpower. You will find the figure 3100.
When I first started playing Train Simulator, I thought this was horsepower and thought "Well that's silly! Everyone knows that's supposed to be 4400!" So when I made scenarios I formed the consists based on a locomotive that produced 3100hp. But then something happened: The loco's performance regularly exceeded the expectations given weight and gradient. So after double-checking all my car weights to confirm the train's trailing tonnage I thought "what if I convert this from kilowatts?" So I loaded up my calculator, opened up the unit converter, selected power, and converted 3100 from kW to hp. The result: 3100kW=4157.168477744587hp. Not quite 4400hp, but much closer than 3100, and it could explain what was going on.
I began to check other Dash 9s and ES44AC/DCs and consistently found this 3100 figure, some having a .4, some a .9, but consistently from this 3100 figure. I even went back to the old eng files from MSTS and found that the developers back then used kW as their unit of measure.
That is when testing began.
I found out several things. First, the advanced FEF-3 is very helpful when determining the weight of your train; all you need to do is subtract 378.8 from the total tonnage in the performance report to get trailing tonnage. Second, wagons with a massinkg line (like most of the stock from the 2016 version of Sherman Hill) do not seem to return a loaded value unless there is a loaded animation (like a container or coal load); wagons with a simple capacity line will return a loaded value. Older stock for whatever reason even though it's loaded doesn't always act like its loaded. Newer stock (like the coal gon from the NS coal district) does indeed act like it's loaded. Third, consistent results come from stock that's already heavy without needing to be loaded (like the LD variants from Stevens Pass). Fourth, even though there is a maxpoweratrail line and even though in reality transmissions are only about 82% efficient on DC locomotives, this line should be the same as the maxpower line in order for accurate results based on real-world practices using equations for a train's top speed given its horsepower-per-ton (hpt) rating.
I used the hpt formula (total horsepower/trailing tonnage = hpt |(hptx12)/% of grade = speed in mph) to make my trains and compare in-game performance.
Here's a test to prove my concept: we're going to make a trailer train on Cajon Pass leaving Barstow using unmodified ES44DCs from Stevens Pass. We'll be using 5 units (I've seen it) and we want our hpt to be about 3.8hpt since this is a high-priority freight. We'll form it in 2 ways: 1)hpt assuming the maxpower line is hp and 2)hpt assuming that the maxpower line is kW.
For the first test, if the maxpower line is hp, then each locomotive produces 3100.4hp. This is the same at the maxpoweratrail line as well. That means we have 15502hp at our disposal. Divide by 3.8 and we get 4079.473684210526 as our tonnage. We'll use the trailers from the SD60M pack since DTG gave that to everyone for free last year. Each trailer weighs 112 tons according to the FEF-3. Divide the above tonnage figure by 112 and we get 36 with a bunch of decimals. This means we can have 36 trailers, which is actually weighs 4032 tons, yielding an adjusted hpt of 3.844742063492063hpt. The max grade between Barstow and Victorville is between .7-.8%, which means we should get a top speed between 57-65mph depending on the grade.
The actual result: We never drop below 67 mph and even hit 70 a few times, higher than our anticipated top speed. To be fair, the grade is not consistent; it rolls up and down, so that could play a role in our final top speed.
For the second test, if the maxpower line is actually kW, then that means we have 20788.52443290213hp at our disposal with our 5 units. That means with a rating of 3.8 hpt we can take as much as 48 trailers with us, totaling out at 5376 tons with an adjusted hpt of 3.86691302695352. If I'm right, we should be able to hit somewhere in the 58-66mph range. If I'm wrong, we should only be able to make between 40-46mph. Take note of what happens here:
On a fairly long piece of .6% grade with the 48 trailers I'm hitting 70 mph - and accelerating! If I was wrong I'd only be doing 57mph. The locos are not modified, the consist is 1344 tons heavier than the last test, and I can still pull this off. With 20788hp on the .6% grade I could theoretically hit 77 (I say theoretically because 77 is above the loco's top speed in the sim file). The only way I could pull this off is if that 3100.4 figure really is in kW instead of hp.
"That loco's set up for 198,012lbf! That's what did it."
Not quite.
Tractive effort tells you how much you can take up the grade; horsepower tells you how quickly you can get that train up the grade (provided you have enough tractive effort to hold the train on the grade in the first place). It doesn't matter how much tractive effort you have - if you don't have the horsepower you won't be going up that grade very fast at all.For the sake of argument, I'll take a loco with the correct amount of tractive effort. This time we'll use FanRailer's modified ES44DC for Stevens Pass for a spin. It has the correct tractive effort. The mod states that tractive horsepower is 4390. We'll use this figure. If I'm right we have 29435.43486661087hp between our 5 locos and take 69 trailers at 7728 tons total. If I'm wrong we'll have 21950hp and take 5712 tons with 51 trailers.
To cut to the chase, we'll go straight to the 69-car trailer train. If we do have 21950hp, then we should expect to only hit between 42-48mph.
With 5 modified locos and 7728 trailing tons I covered 29 miles in 31 minutes 15 seconds with a top speed of 70 - a lot faster than 42-48 mph, even after calculating average speed (average speed was 55.68mph). And for part of the journey I had to reduce power to avoid breaking the speed limit. Seems these locos had no trouble keeping up the pace, which would suggest that again the power is calculated in the sim file as kW.
I modified a Dash 9 for this study, placing 3281.079434961989 in the maxpower line, 142 in the maxforce line, 105.640 in for max continuous tractive effort, matched the maxpoweratrail value with the maxpower line and calculated tractive effort at speed using a formula I found in an old issue of TRAINS magazine:
lbf = (308 x hp)/speed in mph. 308 represents an efficiency of 82% in the prime mover. The lbf was converted straight to newtons then divided by 1000 for kilonewtons.
Suffice it to say that with the same test with 5 engines with approximately 3.8hpt (51 trailers this time) I got very similar results with a top speed of 70. And this is just one example. I've conducted similar tests across the other mountain routes in TS2016 and each still points to the same conclusion: that the max power line is indeed kW and not hp.
So, questions? Comments?
