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Re: Prototype acceleration time question

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  • Steven Fry
    Depends if you re using a fast clock. If yes then 1 minute. If no then 3 minutes. Whereas 5+ minutes would be normal for getting a heavy train up to it s
    Message 1 of 10 , Jun 2, 2007
      Depends if you're using a fast clock. If yes then 1 minute. If no
      then 3 minutes. Whereas 5+ minutes would be normal for getting a
      heavy train up to it's (restricted) top speed I don't think the
      application to model railroading translates too well for this much
      elapsed time.
      Steve F


      --- In z_scale@yahoogroups.com, "Glen Chenier" <glen@...> wrote:
      >
      > --- In z_scale@yahoogroups.com, "Loren Snyder" <ljsnyder@> wrote:
      > >
      > Wouldn't the number of locos and
      > > cars and weight be necessary to figure it?
      >
      > Yes, and climbing a grade at the same time would take even longer,
      but
      > what I am trying to find out is the longest, slowest time that is
      > normal or acceptable in prototype practice with the heaviest trains
      and
      > wimpiest locomotives.
      >
      > Maybe I should re-phrase the question.
      >
      > If you had a power pack with an adjustable momentum feature (from
      zero
      > delay to whatever), what is a realistic maximum time setting to
      > linearly accelerate to full speed from stopped for the slowest and
      > heaviest trains? 1 minute? 3 minutes? 5 minutes?
      >
    • Daniel Baechtold
      Hi guys just got back from my vacation in canada. and got to read more than 50 daily reports -uuh thats a lot! has the problem with the prototype acceleration
      Message 2 of 10 , Jun 18, 2007
        Hi guys

        just got back from my vacation in canada. and got to read more than 50 daily reports -uuh thats a lot!

        has the problem with the prototype acceleration been solved yet? if not I can get you the formula (mattering weight, horsepower, grade..)

        or you can get the easiest explanation: for the heaviest train to accelerate just set the momentum rate at max, at least at 10 minutes!

        for a ratio of horsepower to tonnes of 4:1 (that's quite a high ratio) on best weather conditions from 0 to 62 mph it usually takes me up to 2 minutes (but this is with e-traction, I would have to stick to the formula as diesel traction uses a different acceleration ratio)...

        best wishes from switzerland

        daniel




        2c. Re: Prototype acceleration time question
        Posted by: "Glen Chenier" glen@... zeeglen
        Date: Thu May 31, 2007 4:25 pm ((PDT))

        Wouldn't the number of locos and
        > cars and weight be necessary to figure it?

        Yes, and climbing a grade at the same time would take even longer, but
        what I am trying to find out is the longest, slowest time that is
        normal or acceptable in prototype practice with the heaviest trains and
        wimpiest locomotives.

        Maybe I should re-phrase the question.

        If you had a power pack with an adjustable momentum feature (from zero
        delay to whatever), what is a realistic maximum time setting to
        linearly accelerate to full speed from stopped for the slowest and
        heaviest trains? 1 minute? 3 minutes? 5 minutes?

        --
        daniel baechtold
        erlenstrasse 70
        ch-4058 basel

        daniel.baechtold@...
        http://www.glacier.park.ch.vu/

        Psssst! Schon vom neuen GMX MultiMessenger gehört?
        Der kanns mit allen: http://www.gmx.net/de/go/multimessenger
      • Alan Cox
        On Tue, 19 Jun 2007 01:18:59 +0200 ... Would be interesting although it gets very complex for real diesel electric and electric locomotives as you have field
        Message 3 of 10 , Jun 19, 2007
          On Tue, 19 Jun 2007 01:18:59 +0200
          "Daniel Baechtold" <daniel.baechtold@...> wrote:

          > Hi guys
          >
          > just got back from my vacation in canada. and got to read more than 50 daily reports -uuh thats a lot!
          >
          > has the problem with the prototype acceleration been solved yet? if not I can get you the formula (mattering weight, horsepower, grade..)
          >

          Would be interesting although it gets very complex for real diesel
          electric and electric locomotives as you have field weakening on the
          traction motors which means you get most interesting shaped graphs.

          Some of the railway simulation programs do a passable job at it so you
          could set the thing up in one of them and time it 8)

          Alan
        • Glen Chenier
          ... if not I can get you the formula (mattering weight, horsepower, grade..) ... Thanks for the input, also found this of interest:
          Message 4 of 10 , Jun 19, 2007
            > "Daniel Baechtold" <daniel.baechtold@...> wrote:
            > > has the problem with the prototype acceleration been solved yet?
            if not I can get you the formula (mattering weight, horsepower,
            grade..)
            > >
            > Alan Cox <alan@...> wrote:
            > Would be interesting although it gets very complex for real diesel
            > electric and electric locomotives as you have field weakening on the
            > traction motors which means you get most interesting shaped graphs.


            Thanks for the input, also found this of interest:

            <http://en.wikipedia.org/wiki/Tractive_effort> ,

            which includes links to

            Tractive effort, acceleration and braking
            <http://www.brightlemon.com/ma/what_use/TractiveEffortAccelerationAndB
            raking.doc>

            A Simple Guide to Train Physics
            <http://www.twoof.freeserve.co.uk/motion1.htm>
          • de Champeaux Dominique
            ... Daniel, I imagine the above data matches an euro style passenger train. About NA freight trains, and I don t teach you anything, the ratio is more 1 HP /
            Message 5 of 10 , Jun 22, 2007
              > for a ratio of horsepower to tonnes of 4:1 (that's
              > quite a high ratio) on best weather conditions from
              > 0 to 62 mph it usually takes me up to 2 minutes.

              Daniel, I imagine the above data matches an euro style
              passenger train.

              About NA freight trains, and I don't teach you
              anything, the ratio is more 1 HP / ton on
              flatland....So the acceleration ratio shouldn't be the
              same!

              Dom








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            • Alan Cox
              On Fri, 22 Jun 2007 17:36:41 +0200 (CEST) ... Sounds more like typical freight than passenger (passenger is higher) UK heavy coal freight is typically 3000hp
              Message 6 of 10 , Jun 22, 2007
                On Fri, 22 Jun 2007 17:36:41 +0200 (CEST)
                de Champeaux Dominique <ddechamp71@...> wrote:

                > > for a ratio of horsepower to tonnes of 4:1 (that's
                > > quite a high ratio) on best weather conditions from
                > > 0 to 62 mph it usually takes me up to 2 minutes.
                >
                > Daniel, I imagine the above data matches an euro style
                > passenger train.

                Sounds more like typical freight than passenger (passenger is higher)

                UK heavy coal freight is typically 3000hp for about 1500 tons so 2:1
                ratio with top speeds of around 60 and increasingly 80mph.

                Passenger stuff comes in at between 6:1 (1980's stuff) up to about 20:1
                by my calculations (eg 466 tonnes, 6800hp for the pendolino / 815t,
                16360hp for the eurostar / 50 tonnes, and at the low end 400hp for a
                pacer - essentially a bus on rails). Going back to the mid 1950's we get
                around 4:1

                (those ratios are a fraction high because some of the power goes to ETH
                (HEP to US folks))

                Alan
              • Daniel Baechtold
                Hi Dom, Alan is right, that was the data of a lightweight (~1000t) freight with 1 e-lok (6400kw), I was interested how much time I need for acceleration and
                Message 7 of 10 , Jun 23, 2007
                  Hi Dom,

                  Alan is right, that was the data of a lightweight (~1000t) freight with 1 e-lok (6400kw), I was interested how much time I need for acceleration and stopped time a work ;-) any more prototypical questions I should check at todays work? afterwards I have 3 days off... :-)

                  besides ratio HP/ton there is also a big difference in the graph time/speed of the acceleration. a strong e-lok gets you the exact same acceleration force from 0 kmph (0 kw) up to 80kmph (6400 kw), at 240kn at wheel/track. over 80kmph the acceleration force becomes lower, because the engine has a max output of 6400 kw.

                  a diesel engine can tear away almost anything at low speeds. but to accelerate faster or to reach top speeds, horsepower is often too low. also a problem of european trains is, that you have to get away quickly, but 5km after you'll have to break because of an other red signal. so a diesel engine is most uneconomical at such a driving style, but makes sense for north american trains with hauling tons over tons no (almost) matter how fast, but sure you get your train a the top.

                  greetings from small switzerland

                  daniel


                  > > for a ratio of horsepower to tonnes of 4:1 (that's
                  > > quite a high ratio) on best weather conditions from
                  > > 0 to 62 mph it usually takes me up to 2 minutes.
                  >
                  > Daniel, I imagine the above data matches an euro style
                  > passenger train.

                  Sounds more like typical freight than passenger (passenger is higher)

                  UK heavy coal freight is typically 3000hp for about 1500 tons so 2:1
                  ratio with top speeds of around 60 and increasingly 80mph.

                  Passenger stuff comes in at between 6:1 (1980's stuff) up to about 20:1
                  by my calculations (eg 466 tonnes, 6800hp for the pendolino / 815t,
                  16360hp for the eurostar / 50 tonnes, and at the low end 400hp for a
                  pacer - essentially a bus on rails). Going back to the mid 1950's we get
                  around 4:1

                  (those ratios are a fraction high because some of the power goes to ETH
                  (HEP to US folks))

                  Alan
                  --
                  daniel baechtold
                  erlenstrasse 70
                  ch-4058 basel

                  daniel.baechtold@...
                  http://www.glacier.park.ch.vu/

                  Psssst! Schon vom neuen GMX MultiMessenger gehört?
                  Der kanns mit allen: http://www.gmx.net/de/go/multimessenger
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