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Scale Speeds

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  • Member since
    April 2003
  • 305,205 posts
Scale Speeds
Posted by Anonymous on Sunday, November 23, 2003 3:12 PM
Hey, it's me again with another rookie type topic. What's the view on scale speeds? I'm working with N scale and I'm trying to figure out what a "realistic" speed would be. FIRST, I need to know how fast REAL trains go when they are "highballing" these days. I THINK 33 feet equals one scale mile, RIGHT? I have a new Atlas GP that goes rather slowly (comparatively). I THINK that is by design to help us GO scale speed. I have on OLD..VERY OLD Atlas-Rivarossi E-8 that goes SO fast it leaves the track on curves.......
Thoughts?
Max
  • Member since
    April 2003
  • From: US
  • 1,522 posts
Posted by AltonFan on Sunday, November 23, 2003 5:28 PM
There is a kind of complex formula for determining scale speed:

(((IN/12)*SF)/5280)/(SEC*(1/60)*(1/60))

Where IN= inches traveled
SF= Scale Factor (i.e., 160 for N. 87.1 for HO, 48 for O, etc.)
SEC= Seconds it took to travel IN (inches travelled)

(The above equation can be pasted into an Excel spreadsheet.)

One thing to keep in mind is that if one is viewing a train close up, 60 mph looks very sickeningly fast; from a mountain miles away, it will look very slow. (Watch an airplane go by; they travel at hundreds of miles per hour, but don't look very fast from the ground.) In N scale, we are viewing our models as if from a tall building, or flying aircraft, or a tall mountain, hence our model going at 110 scale mph looks very slow.

Dan

  • Member since
    April 2003
  • 305,205 posts
Posted by Anonymous on Sunday, November 23, 2003 5:55 PM
As far as what realistic train speeds are, it does depend on what type of cargo is being hauled, as well as the condition of the mainline. The Shinkansen Bullet Trains in Japan are built to go over 125 mph routinely, but they are run on dedicated mainlines that have extremely broad curves and little interference from other trains. An American freight train might get up to 50 to 60 mph if it is traversing easy terrain, but then up in the mountains where steep climbs and sharp curves are the norm, it'll probably drop to around 20 mph. Some freight trains carry time-conscious commodities and are run on schedules that have them overtaking all the others in order to maintain a high speed; I am thinking of the intermodal (trailer-on-flat-car) trains that Santa Fe (now BNSF) races across the desert southwest at 80 mph. To acheive the high speed, they would stack a bunch of deisels on the front end of the train, more than would ordinarily be needed to simply move the fairly light TOFC traffic. My favorite trains, long coal drags, are not time-sensitive at all, and thus tend to move at rather slow speeds, with as many cars in the train as the engines can haul.

Passenger trains always want to run as fast as possible, but in practical terms this rarely exceeds 100 mph on American rails. An exception might be the Northeast Corridor, where some specialized trainsets run.

Most older N-scale equipment is geared to have top speeds in the 150-200 mph range, which is well beyond what the real engines were capable of. Higher-quality equipment is beginning to get better, with top speeds that are closer to the rated top speeds of the prototypes. A sign of good quality in an N-scale engine is how slow you can make it run; you want it to start smoothly at close to 1 mph, right at the bottom of your throttle's range, and then top out at a realistic 80-100 mph at full throttle. If it tops out higher than this, you can always just limit your throttle, but if it doesn't start smoothly at a few scale mph, then you'll have difficulty doing switching moves and such.
  • Member since
    January 2001
  • From: Guelph, Ont.
  • 1,476 posts
Posted by BR60103 on Monday, November 24, 2003 10:55 PM
Some of the prototype railroads are starting to catch up with the speeds that we modellers have been capable of for a hundred years. [:D]
The was a rule of thumb that steam locos had a maximum speed in miles per hour of the driver diameter in inches. (This was ignored at the top end of locomotives as very few had drives even approaching 100".) This would mean that there was a maximum revolutions per second or minute that they should be operated at.
The calculation is left as an exercise for the student.

--David

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