Long time no see

[Chris]

Hey there folks, long time no see. I do apologize for my "on again, off again" appearance in this forum.

Turning to my area of special interest: LCO files. I seem to remember that the elusive "Value 1" and "Value 2" were determined to be "Weight of train that can be pulled" and "traction", respectively. Does this still hold, or have we come to new insight?

After much frustration ( ), I may have found something. I think I have figured a way to calculate value 2 and come pretty close. For some of the default locomotives it is spot on (such as H10 and the Big Boy), for some a little on the low side. The Challenger comes out way low (or, in the game way high). It would seem that WHEN this calculation comes out low compared to the default values, the more powerful the locomotive the bigger the difference.

Essentially it involves first calculating cylinder horsepower:

((Cylinder diameter^2 * Cylinder stroke * boiler pressure * speed) / (driver diameter/375))/4

For articulated/compounds multiply this by 2 (i.e. the big boy and challenger).

Actually, speed will end up being irrelevant to the final number.

Then calculating power:

(cylinder horsepower*375)/speed

Divide that by 1000 (probably for easier numbers). Call this "Value X"

I have include an automatic correction factor:

Value X * ((Value X/300)+1)

Essentially this adds a percentage to make it come out a little better. If you fill in the numbers for the Big Boy:

Cylinder diameter: 23.75
Cylinder stroke: 32
Boiler pressure: 300
Driver diameter: 68
Speed (irrelevant, enter any number)

Result: 45.1, right on the money. Game is 45.

For the H10, use the H6 (which was actually started in 1918; the H10 is a little later. So strictly the in game 2-8-2 is a H6). Result: 16.95. Game is 17.

Sounds plausible? If anyone wants the spreadsheet, drop me a line. Any errors, serious mistakes of logic (entirely possible), please let me know.

Regards, Chris

[bombardiere]

Hello Chris

Nice to see you again.

Very interesting. How in the earth you did figured out all this calculation

What I am most interested in, is that how this affect the new engines we have made. I have selected #2 based on game balance and how these engines fit into existing engine line up. The data I have mainly look at were traction and wheel size and count.

Speed is problematic as steam engines don't have absolute top speed.

P.S. I don't know if you seen it, but some time ago I figured out what #5 & #6 are. Engine sound and whistle sound.

[Chris]

How in the earth you did figured out all this calculation

Luck. I knew there had to be some logic or formula for this, because you don't just come up with something like "6.3" or "17.7". I have played around with these numbers so often and always hit a brick wall. This time I was lucky.

I am planning to run a bunch of locomotives through this formula and see what comes out. Problem is, while I have data for quite a few North American locomotives (mostly 1920's - 1940's), I don't have all of them and I have nothing for European locomotives. If you have the data needed in the formula I will be glad to run it through. The formula only works in the standard system (i.e. U.S.), so anything metric I would have to convert. No problem with centimeters and kilograms, but when things get to kilo Newton and Pascals, I get lost.

This morning something else struck me. A number of locomotives have value 2's which are higher in the game than this formula suggests (such as the Northern and the Challenger). It seems to me that these are the same locomotives that in real-life have a higher top speed (Perhaps better: accepted top speed) than in the game. In other words, it appears that for some locomotives the builders reduced the top speed and to compensate for that increased value 2. While the in-game Northern is a pretty generic Northern, most Northerns I have calculated come in somewhere between 19 and 21 as opposed to 23. However, most Northerns also do more than 67 mph.

Same on the Challenger. Difference here is that the in-game Challenger is a very specific type (which can be deduced from the availability date). The in-game value 2 is 40. I don't get much beyond 31. BIG difference. However, the real-life Challenger does 70 mph (according to Union Pacific's website, so I consider that pretty reliable info). In the game it is limited to 60 mph.

Regards, Chris

[bombardiere]

Chris I believe that you might have struck into something. I have noted this connection between speed and #2. I have used it as a rule of thump that high top speed means lower #2. And for our calculation process the top speed doesn't need to be absolute, but what we decide to be a convenient game top speed.

If you are interested in doing calculations US 20s' -40s' is a good place to start. In fact I am planning to do some American engines. USRA 0-8-0 is only a start and I have a long list of engines that are possible to do with relative ease.

I have info of some Euro engines and many Brit, but I have no railway book library. In fact I have only one international locomotive book, but judging by game's engine selection, Poptop has the same book ;)

Btw what you said about H10 is interesting as I have based my assumption on the fact that the game's version is more powerful H10 rather than standard H6. (for generic purposes H6 would have been much better choice) And I am not happy with game's Northern. Performance and looks do not represent early Northern as far as I know. It looks more like a Daylight Northern. (I wonder if it would be possible to remove that “thing” above the boiler)

P.S. We did mess with the Northern in the loco pack, but I wasn't entirely satisfied on what came out. I think that if Northern's top speed is better, then its #2 should be lower. (perhaps around that 19 you calculated.)

Anyway, I am highly interested in results of your calculations, but at the moment your formula is above my head. ( i need to disgest about it more)

[Chris]

There are flaws though in these calculations, something I will have to look into more deeply. For example, formula 1 gtives us cylinder horsepower. Formula 2 takes drawbar horsepower as input. Not the same thing.

Also, for some engines I have (historic) numbers for drawbar and cylinder horsepower. Drawbar horsepower can't be calculated without on the road testing (apparently). But there is a formula for cylinder horsepower, that I used here. I got it from a old Baldwin publication I found on the internet somewhere (if memory serves), but I have seen it in several places. Problem is, the cylinder horsepower that comes out of it is in some cases significantly lower than the historical numbers. For example, last night I was looking at the New York Central Niagara, S-1b (4-8-4). Cylinder horsepower at 85 mph was given as around 6600 (I don't have the data here now). The formula comes out 50% lower. BIG difference. Of course, it is still entirely possible that Pop Top used the standard formula, without regard to other considerations.

More later.

Regards, Chris

[bombardiere]

Still, a great work.

As this is a game I feel that we can use approximations. And if the results are way off, we can use our own judgement.

But, Sorry Chris I couldn't figure out your calculations. I got weird results anything between 9 and 1516. I am missing something elementary...

Anyway could you please calculate two specs for. (I am curious)

USRA 0-8-0

Cylinder Dia. 25In
Cylinder Strk. 28In
Boiler Pressure 175 psi
Driver Dia. 51In
Speed 45 mph

Class M2 4-8-0

Cylinder Dia. 24In
Cylinder Strk. 30In
Boiler Pressure 200 psi
Driver Dia. 56In
Speed 60 mph

Ta

P.S. I found accidentally following super site. It has all the info needed. (Euro engines with metric of course. I have no clue what atmospheric pressure means ) And of course there is no guarantee how accurate the data is. But I guess it is good enough for this use.

http://orion.math.iastate.edu/jdhsmith/term/slindex.htm

[Silverback]

Try this site for a Tractive Effort calculator for US Locos

http://www.steamlocomotive.com/misc/Tra ... fort.shtml

[Chris]

OK, these are the figures I am getting:

USRA 0-8-0
Cylinder horsepower: 1801
Value 2: 15.01 uncorrected, 15.76 corrected.

The "corrected" value simply adds a percentage. Works for the H10 (H6) and Big boy, but as you correctly say: use your own judgement.

M2 4-8-0
Cylinder horsepower: 2468
Value 2: 15.42 uncorrected, 16.22 corrected.

Does this sound plausible?

The PRR G-5 with specs:
Cylinder dia: 24"
Cylinder stroke: 28"
Boiler pressure: 205 psi
Drivers: 68"

Cylinder horsepower: 1944
Value 2: 12.15 uncorrected, 12.64 corrected.

The P-2 (4-8-2)
Cylinder dia: 29"
Cylinder stroke: 28"
Boiler: 200 psi
Drivers: 73"

Cylinder horsepower: 2580
Value 2: 16.12 uncorrected, 16.99 corrected.

Hudson J-1b
Cylinder dia: 25"
Cylinder stroke: 28"
Boiler: 225 psi
Drivers: 79"

Cylinder horsepower: 1993
Value 2: 12.46 uncorrected, 12.97 corrected.

This is one of my favorite locomotives, I love it. I wish someone would correct the smallest picture/icon so I can distinguish it from the Pacific in the train list. By the way, there was only 1 J-1a, number 5200 which was the prototype. Number 5201 was a J-1b. Quite a few of these were made, before the J-1c, J-1d, etc. So it would be more appropriate to call it a J-1b.

Regards, Chris

[EPH]

If the original maker wouldn't mind sending me the artwork I'd be happy to paint a new profile (but not a beauty shot :) ).

[wsherrick]

There is another vital statistic that needs to be considered and that is tractive effort or how much pulling power a locomotive develops at starting. I am not sure of the formula (I could look it up) Tractive effort is taken from indicated cylinder horsepower (which depends on boiler pressure, piston stroke and numerous other factors) and the weight on the drivers. Another phrase for this is the,"factor of adhesion." High horsepower does not always translate into start up pulling power.
Horsepower delivers pulling power at speed and also the absolute top speed capabilities of a locomotive while pulling X amount of tons. Not the power to start a standing train. Start up power is dependant upon the tractive effort of a locomotive ie. the engine's ability to grip the rail and pull the train away from a dead stop. I hope I have not confused anyone.

By the way, I applaud the efforts to figure out how all this is calculated in the game. I find it very interesting. :D

[Chris]

Yes, I find it odd that Tractive Effort (TE) doesn't appear to be involved in the numbers of RT3 locomotives. At least I have not yet been able to find where that comes in. I have the formula for Tractive Effort at home. Very interesting. As I understand it the Adhesion Ratio (AR) is Weight on Drivers (WoD) divided by TE. Ideal for steam locomotives is 4. Lower and the locomotive is said to be "light on its feet", which I assume means it is prone to slipping. More and it has more weight than necessary. From that you can calculate effective TE: If AR is less than 4 it can't apply all the TE and effective TE is lower than calculated Tractive Effort. Correct me if I am wrong on this. I have a big spreadsheet at home with lots of these calculations and numbers for a whole bunch of locomotives (all North American, mostly 1920's - 1940's).

The explanation I have read for starting and pulling power goes something along the lines of: If a steam locomotive can start a train, it can usually pull it at sufficient speed. Horsepower being low at low speed, the horsepower of a steam locomotive picks up as it accelerates. Thus, a steam locomotives best power comes in when it is moving along nicely.

A diesel on the other hand has maximum power at low speed and drops off as it picks up. The story of at low speed the amp meter reading high and the volt meter low (low speed, high power). As it accelerates the volt meter goes up and the amp meter down. Essentially a trade off between power and speed. So it "runs out of steam" so to speak Apparently any diesel locomotive can pull pretty much any train. It just might not be able to move it very quickly. Again, correct me if I am wrong on this.

Regards, Chris

[bombardiere]

Sounds plausible Chris :) I am only guessing but Tractive effort is connected with what we call #1 “free weight” (how much the engine can pull before the speed drops) And possibly to acceleration.

Anyway thanks for the calculations. It seems that I have been conservative with #2. That as been partly for purpose, because I want to avoid making super engines. If I can trust on my own posting, I have made USRA as 12. And my G-5 is much bellow (around 6) of your result. Well people have been saying that it was a strong puller. (with this info I seriously consider giving forthcoming Class M2 Mastodon #2 at least 14)

I would like to see your spreadsheet. Do you still have my email?

EPH. I have been lazy with J-1. I will send the original texture skin to you sometime this weekend. I can do the final converting and renaming. You can use H10 profile as base, just change the wheels.

[Chris]

It seems that I have been conservative with #2. That as been partly for purpose, because I want to avoid making super engines.

At the same rate I am going to have to de-rate the P-2 a bit. Not a popular move, I suspect but accuracy before all. If memory serves it is a bit stronger than 17 at the moment. Essentially it is a passenger version of the 2-8-2, a bit faster.

I will be trying to nail #1 down more accurately. Might take a while though.

Yes, my e-mail hasn't changed, I will be happy to mail it to you. What's your e-mail again?

I am also planning on making a beta version of a "corrected" Challenger. This will be a CSA-1, available 1936. Speed 68~70MPH, but value #2 down from 40 to about 31. See how that works out.

Regards, Chris

[bombardiere]

I'll reply to this right away, before I go home from the office. :D

At the same rate I am going to have to de-rate the P-2 a bit. Not a popular move, I suspect but accuracy before all. If memory serves it is a bit stronger than 17 at the moment. Essentially it is a passenger version of the 2-8-2, a bit faster.

There are several versions of P-2 floating around. I have a list here at the work with me (I wanted to print it recently. my own printer is kaputt), which says P-2 values would be 72 mph, #1 140 #2 14. I think it is "loco pack" version (we have had this discussion before), but I can't verify it. If so P-2 doesn't need downgrading.

I am also planning on making a beta version of a "corrected" Challenger. This will be a CSA-1, available 1936. Speed 68~70MPH, but value #2 down from 40 to about 31. See how that works out.

Sounds good to me.

Now that Milo's Patch work is delayed, we could have another look into locos again. (more testing this time ;) ) I don't have major issues, but recent discussion have made me think to that Atlantic should be faster. May be 85 mph

P.S. I'll mail to you

[wsherrick]

[quote="
A diesel on the other hand has maximum power at low speed and drops off as it picks up. The story of at low speed the amp meter reading high and the volt meter low (low speed, high power). As it accelerates the volt meter goes up and the amp meter down. Essentially a trade off between power and speed. So it "runs out of steam" so to speak Apparently any diesel locomotive can pull pretty much any train. It just might not be able to move it very quickly. Again, correct me if I am wrong on this.

A diesel can NOT pull any kind of train(please see my post in,"locomotives,in this section") You are correct in your statement that a steam engine's horsepower curve goes up as speed increases and a diesel's goes down. The problem with starting a diesel is it's weight to power ratio or factor of adhesion. On paper a diesel has an advantage over steam because of the electric traction motor's "continuous torque at starting," however; in actual practice that continous torque is no good when you don't have enough weight on the drivers to take advantage of it. Most diesels will slip badly at starting because their starting horsepower exceeds the factor of adhesion. EMD's are especially bad in this area as one of the selling points was and is more horsepower for less wieght on the drivers. Another issue is the engineer's ability to properly use the throttle. On all EMD's and GE locomotives you have an electric throttle. This throttle is seperated into 8 notches. One being the lowest and 8 the highest. Many times in starting a train you don't have enough power in one notch and the next notch up is too much power. I have had diesels unable to start or pull trains that are well within their theorectical ability to pull, because you can't finesse the throttle. One way that I use to overcome this flaw as well as other engineer's, is to set the independant brake on the engine wheels to prevent slipping as you are starting. This causes the traction motors to pull against the brakes and thus you can get the train rolling without too much slippage. Of course this spikes the Amperes up into the danger catagory and if you don't watch it you can burn out a traction motor. Many times this is the only way to start the train.
Now steam locomotives on the other hand can often start trains that are much heavier than they are rated for. A steam locomotives power curve goes up quickly once the train is started. If you can get the train up to 3 or 4 mph you are golden. A steam locomotive is only as good as the skill level of the engineer. The throttle on a steam engine has an infinite number of settings between being closed and fully open. You use the throttle in combination with the reverse lever to develop power. The reverse lever controls how much steam is admitted to the cylinder during the piston stroke. It took me a long time to learn how to use the throttle and the valve setting to my advantage. I have started trains with a steam engine that a diesel with an equivalent horsepower rating could not start because I had the ability to work the throttle and valve setting just right to get the train started. The diesel might have moved the train from a start but as it's horsepower rating drops rapidly after about 2 mph it can't get the train underway. It will slow down and as it slows the horsepower will spike (as indicated by the amp meter spiking upward) then this surge of power causes the engine to slip because the engine does not have enough weight on the drivers to grip the rail. That is why you need three or four diesel units to pull what one ordinary steam locomotive can pull.

[Chris]

Very interesting! Does this mean that diesels often don't have the same Adhesion Ration as steam locomotives, which I gather is ideally 4, but ought to?

Regards, Chris

[wsherrick]

Yes, you are correct. Some railroads fill their diesels with old rail and concrete to make them heavier. Of course its a dirty little secret so don't tell anybody.

[bombardiere]

Chris, I finally cracked your calculations.

It took me this long because there was a slight error in your formula. Instead of dividing driver diameter with 375, it should be multipled

Still huge for your work. This is valuable data for me, even if it is only foundation on my own judgement.

I guess in principle same formula could be used to calculate values for electric and diesel locomotives, as often the engine horsepower is know. However, as Wsherrick pointed out, diesel do behave differently, so I don't know if it work in practise.
[/quote]

[Chris]

Oops.... Yes you are absolutely right. Multiply by 375.

Regards, Chris

[bombardiere]

I calculated few European engines (where I could find the data in Imperial) and some Brits. At first it looked like Poptop has been generous for European engines. Stronger than should be by compared to Americans. But then I realised that pesky Euro engines sometimes have three or four cylinders.

Still, I think that Poptop has the speed included in some way in the calculations, because the calculations give higher #2 for really fast engines, such as Mallard, Sterling and Penn Pacific.