Scale power and weight

Discussion in 'FAQs' started by LoudMusic, Sep 5, 2006.

  1. LoudMusic

    LoudMusic Member

    Does anyone factor fuel into their modeling? Like, stopping to refuel? Or does the maintenence crew take care of all that while you're away at dinner? :)
  2. pgandw

    pgandw Active Member

    Way back in the '60s, John Allen had proposed a motor driven "count down" odometer that would indicate water and/or coal usage. It would be powered off the DC track voltage so that speed would affect the rate of usage.

    With today's electronics, a similar device could be easily designed (for DCC, you'd need a decoder set to the same address as the chosen locomotive in front of the device to provide the drive and respond to the correct throttle inputs). Could be a hoot if you could calibrate fuel/water/sand usage rates and capacities to fit your layout and operations. Even more fun if there would be a significant difference between a "good" engineer and a "not-so-good" engineer.

    On the other hand, from what I understand, diesel switchers used in yard duty or on short lines are only refueled once a week. Steam engines to be used the next day generally had the fire banked, but were not allowed to go "cold". Firing a steam engine from cold iron to ready to pull a train was not a trivial exercise - it generally took hours of careful and hard work. For steam, spacing between fuel and water stops was a series of design trade-offs of tender and engine size, and cost of support infrastructure.

    my thoughts, your choices
  3. LoudMusic

    LoudMusic Member

    That would be really interesting. I'd want some kind of amplifier so that more voltage used the count down more quickly, simulating aerodynamic drag and loss of effeciency.

    If the DCC system were monitored / controled by a computer it could simply keep track of all the locos' fuel and cut their performance when the tank was getting low. I'd bet someone has already accomplished both our techinques - need to do some research :)

    This is all very interesting. I would imagine that it's so rarely an issue anymore that the short periods of time we spend running trains on our layouts there would never be a need to break for fuel. 4000 gallons is a LOT of go-juice.

    But on that note, what kind of fuel effeciency does such a beast get? Sticking with the SD40-2, lets say it's pulling 75% its maximum load at an average speed of 50mph, how many miles can it haul that train before the fuel tank goes dry? Is it ever necessary for the train to include a seperate fuel car behind the engines? Or are the engines already able to hold out longer than the engineers?
  4. Russ Bellinis

    Russ Bellinis Active Member

    BN or UP used to run a tank car loaded with diesel fuel in the middle of a 4 engine consist, but I think it was more for economy than operational needs. As I remember the fuel was less expensive in one part of the railroad than in other parts, so they would send the train out from where they had the cheap fuel with the locomotive tanks topped off and the tank car topped off, and then as they used fuel from the loco tanks, they would transfer in fuel from the tank car to get through the area where the fuel was more expensive until they could get back to where they got the cheaper fuel.

    On a model railroad, I'm not sure refueling is an issue with modern power. I'm not sure how often the prototypes need to be refueled, but it is seldom enough that when UP bought SP, they were leaving trains idling on sidings waiting for crews to bring them in. Unfortunately, part of the problem they had was that the trains would be left on the siding for so long they would run out of fuel while idling. Restarting a diesel engine that has run out of fuel is not very easy either. I suspect, based on how long it took us to bleed off small diesels in transport refrigeration units that ran out of fuel and went airbound, that a four unit set of dieasels that ran out of fuel would probably take a mechanic 1 hour each unit at least to get them started after they got a fuel truck out to the siding to refuel the engines. Whether the U.P. was sending one mechanic to start all dead units in a consist, or if they sent a crew of mechanics to work on starting all units at the same time, I don't know. I would imagine they would send at least two men at a time, so that if there was an accident, there would be help available.
  5. 60103

    60103 Pooh Bah

    There was a headline in Trains news last week "UP fails to fuel METRA locomotive; commuters stranded".
    In most places, water was the critial fuel for steam engines. A lot more water than coal was used, but water was generally availble locally and cheaply, so tenders were designed to be filled with water many times before they had to re-coal. This is why almost every station had a water tank and non-stop trains had troughs.
  6. Russ Bellinis

    Russ Bellinis Active Member

    That was also why the Santa Fe was one of the first class 1 railroads to dieselize. None of the water available in the dessert was usable for steam. It had so much alkali that it would fould the tubes in short order. The result was the Santa Fe had to import all of the water used on their steamers for probably 40% if the mainline!
  7. loggerhead

    loggerhead New Member

    Using the equation X=1/2at*t where X is the distance and the acceleration due to gravity is 9.8 meters/second squared. The time is therefore the square root of (2*X/9.8). Assuming an ideal system with no air drag. The height of a 170 ft trestle is 51.8 meters and .59 meters respectivly in HO scale, therefore the train will fall in 3.2 seconds in real life and will take .35 seconds to fall the HO distance. This is why many of the movies film models with high speed film in order to slow the frame down to realistic speeds.
  8. LoudMusic

    LoudMusic Member


    That's EXACTLY what I was going to say.

  9. 60103

    60103 Pooh Bah

    Thanks, loggerhead. My physics and calculus texts have been packed away somewhere for about 40 years.

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