TNE Only: Locomotive design sequence

[TheDark]

It is possible I am misremembering, but I seem to recall someone had posted an FF&S design sequence for locomotives. However, I cannot find it now. Does anyone know where in the vast internet this might be located?

 

[LeperColony]

Off hand, the only reference I've ever heard was where Ask Dave pointed out that they never really managed to get an adequate locomotive design system.

 

[TheDark]

Off hand, the only reference I've ever heard was where Ask Dave pointed out that they never really managed to get an adequate locomotive design system.

I ran across that during my Google search. I feel like I saw one that included the power generation tables and part of the design sequence included calculating stats for the locomotive on its own and with different masses based on expected consists. I was thinking it might have been the one Dave mentioned, posted by whoever wrote the system, but now I can't find it.

 

[Timerover51]

Are you looking forward to a locomotive design of a specific type of locomotive, or just a good description of a locomotive design?

 

[whartung]

And what are you looking for in locomotive design?

Specifically, about the only thing that a locomotive really has going for it in distinction to any other wheeled vehicle is it's necessity for weight to provide tractive force in order to pull the cars.

Obviously, when you get in to the weeds and consider the differences between, say, a narrow gauge gear driven locomotive and a 4-8-8-4 mountain locomotive are more than just raw horsepower and length.

But, for most purposes, especially game purposes? There's really NOT that much difference.

Then it comes down to basically steam power plant design or, in the modern age, electric motor design.

So, what exactly are you looking for in a design sequence for locomotives?

 

[TheDark]

I'm really just looking for something in the vein of the other vehicle construction segments, where the various inputs of size, material, power plant, etc, end up giving protective value, speed, range, etc. I'd like to be able to do up armored trains at various tech levels.

 

[TheDark]

I've kept doing research on this, and have the start of a design sequence, although I need to spend a lot of time at some point converting from imperial to metric. Here's the start of what I have for steam locomotives:

MW * 1341.02 = horsepower

For TL3, horsepower/4.24 = area of cylinder face (in in^2) = Ca
For TL4, horsepower/7.42 = area of cylinder face (in in^2) = Ca

2*((Ca/3.14)^0.5) = cylinder diameter = Cd

0.85 * P * Cd * (10*Cd/7) / D = Tmax
P = boiler pressure in psi (200 for TL3, 350 for TL4)
Cd = cylinder diameter in inches
(10*Cd/7) = typical piston stroke in inches (10/7 the bore diameter)
D = diameter of driving wheels in inches
Tmax = maximum tractive effort in pounds

1.2*D = maximum speed for driving wheels in miles per hour

Tmax/0.0625 = weight on driving wheels (pounds)

Each ton pulled requires 4 pounds of tractive effort = Ta (pounds)

375 * horsepower / Ta = maximum speed at load (miles per hour)

Top safe speed is the lower of 1.2*D or 375*hp/Ta. Larger wheels will maximize 1.2*D, smaller wheels will maximize 375*hp/Ta.

Acceleration in mph per 5-second round is 90*hp/Ta.


Rail is measured by weight in pounds per yard or kilograms per metre; the conversion between the two is effectively 2 lbs/yd = 1 kg/m. The maximum axle load for either is 560 * rail weight (i.e. a 50-pound rail can have a maximum weight per axle of 28,000 pounds). Rail weight = rw

Tmax/(560*rw) = number of driving axles required.

Grate area of firebox in square feet = Tmax/600


Things I don't have yet: Carrying wheels (leading bogies, trailing bogies, etc). Weight for non-engine items. Bogie requirements for high speed. Percentage of locomotive weight carried by carrying wheels. Compound engines. Non-steam engines. Stoking (either by fireman or mechanical stoker). Water consumption. Sanding. I'm sure there are other things as well, but those are what pop to mind as I'm writing this.

 

[Timerover51]

I was going through one of my Army transportation manuals, and it had a section on military railroads. Two locomotives were mentioned, one steam-powered and one narrow-gauge gasoline-engine powered. The steam locomotive was a big one, and used 4.400 pounds of coal and 3,400 gallons of water per hour. The tender was good for 10 tons of coal, but only 7,000 gallons of water, so it would need water every two hours. I would have to go back and take a look at the narrow-gauge engine gasoline consumption.

Also, have you looked at Project Gutenberg for information on the development of the locomotive? There is quite a lot there covering the development of the steam locomotive.

 

[TheDark]

I was going through one of my Army transportation manuals, and it had a section on military railroads. Two locomotives were mentioned, one steam-powered and one narrow-gauge gasoline-engine powered. The steam locomotive was a big one, and used 4.400 pounds of coal and 3,400 gallons of water per hour. The tender was good for 10 tons of coal, but only 7,000 gallons of water, so it would need water every two hours. I would have to go back and take a look at the narrow-gauge engine gasoline consumption.

Yeah, consumptions could get huge. During their original tests, the Big Boys went through 8-10 tons of coal and 38-42 tons (10k-11.5k gallons) of water per hour. They carried 28 tons of coal and 25k gallons of water to get 2-2.5 hours of endurance.

Also, have you looked at Project Gutenberg for information on the development of the locomotive? There is quite a lot there covering the development of the steam locomotive.

I haven't, but I managed to pick up a copy of J. G. A. Meyer's Modern Locomotive Construction of 1892 for information on how things were done.

 

[Timerover51]

Just checking on what you had.

 

[TheDark]

Just checking on what you had.

No worries. I'm always looking for more sources, since I never know when someone will randomly mention something that's of use. I ran into a paper today that made me realize I had misunderstood some numbers - I thought they were one of the inputs into an adhesion formula, but they were actually the result of that formula.

Two little informative tidbits for today:
The equations to calculate Ca are based on boiler pressures of 200 psi for TL3 and 350 psi for TL4, both of which are numbers achieved late in that TL. The actual formula is horsepower = .0212 * boiler pressure * cylinder face area, so if you want to use a different boiler pressure, then the formula for Ca becomes:
Horsepower/(.0212*pressure) = Ca

In metric, rail weight (kilograms/meter) doubled is the tonnes per kilometer (since there are two rails). And, from FF&S, we know iron costs 0.0002 MCr per tonne. So, each kilogram/meter of rail costs .0004 MCr per kilometer; that is, to lay a rail of 50 kilograms/meter of mass means each kilometer of railroad rails costs .002 MCr, and rail of 100 kilograms/meter costs .004 MCr per kilometer.

 

[Timerover51]

No worries. I'm always looking for more sources, since I never know when someone will randomly mention something that's of use. I ran into a paper today that made me realize I had misunderstood some numbers - I thought they were one of the inputs into an adhesion formula, but they were actually the result of that formula.

Two little informative tidbits for today:
The equations to calculate Ca are based on boiler pressures of 200 psi for TL3 and 350 psi for TL4, both of which are numbers achieved late in that TL. The actual formula is horsepower = .0212 * boiler pressure * cylinder face area, so if you want to use a different boiler pressure, then the formula for Ca becomes:
Horsepower/(.0212*pressure) = Ca

What is your Earth time frame cut-off for Tech Level 3 and Tech Level 4? In 1860, locomotives were still using rectangular boilers with a pressure of 30 psi made of iron (hence the term "boiler plate"), while in 1900 drum boilers were in use, made of steel, and going up to 250 psi.

In metric, rail weight (kilograms/meter) doubled is the tonnes per kilometer (since there are two rails). And, from FF&S, we know iron costs 0.0002 MCr per tonne. So, each kilogram/meter of rail costs .0004 MCr per kilometer; that is, to lay a rail of 50 kilograms/meter of mass means each kilometer of railroad rails costs .002 MCr, and rail of 100 kilograms/meter costs .004 MCr per kilometer.

Your rail weight of 50 kilograms per meter is about correct for today, but your higher weight is too high. Also, iron rails will wear out in about 3 to 5 years, while steel rails will last about double that.

 

[kilemall]

Don't forget higher tech locomotives, such as maglev hover or low-power grav.

 

[TheDark]

What is your Earth time frame cut-off for Tech Level 3 and Tech Level 4? In 1860, locomotives were still using rectangular boilers with a pressure of 30 psi made of iron (hence the term "boiler plate"), while in 1900 drum boilers were in use, made of steel, and going up to 250 psi.

I generally start to transition from 3 to 4 around 1880 (since 4 is "circa 1900" and only lasts until around 1930). The 350 psi for TL4 is from the Baldwin 60000 prototype, which was one of the lowest-pressure superheated steam locomotives (most of which were failures).

Your rail weight of 50 kilograms per meter is about correct for today, but your higher weight is too high. Also, iron rails will wear out in about 3 to 5 years, while steel rails will last about double that.

If we're talking about in the real world, true, the heaviest mass-produced steel rails were 77 kg/m monsters used by the PRR. That wouldn't necessarily limit someone on another planet. Rail material will be more detailed later (assuming I don't get distracted too much by paying work and other projects). Historically, mechanically-powered railroads started with wood and strap-iron, moved to solid iron in the 1840s, and then steel in the mid-to-late-1860s. Some iron rails wore out in three months on the PRR. When the Chalk Farm Bridge near London tested steel rails on the same line as iron rails, the wear was found to be roughly 1/17th as much for steel.

Don't forget higher tech locomotives, such as maglev hover or low-power grav.

I should get there eventually, but I need to get the basics first before moving on.