At a recent convention, someone mentioned a chart or table that is used to calculate the approximate scale speed of a model train. It sounded like a basic matter of timing the locomotive between two precisely placed and measured markers and then referencing that time on the chart to find the speed the train would be traveling. Can anyone tell me where I can find that chart and the marker distance information? I thought the person said they took it off of the NMRA website, but I haven’t been able to find it there. Thanks.
If you have s spreadsheet (available on most PCs) and know how to use it, it is a snap to make just such a chart. You can tailor it for your scale, the distance between the two markers or any number of marker pairs, the speed range you want to cover, etc.
A short approx method in HO.
Footage divided by time=? X 60 = scale speed
Take a 40 foot round section, start to finish
in 20 seconds, equals 2,X60,= 120MPH
The speed of one foot per second= 60 MPH
I use this method to rate & compare my locos.
A precise calculation would be done this way:
distance in inches x (25.4 x 5280 / (3600 x 3.5)) divided by the time in seconds = scale mph
When you work out the arithmatic it is
distance in inches x 10.64381 / time in seconds = scale mph
This is for HO scale.
Example - 36 inch flex track crossed in 5 seconds = 77 smph(HO)
Enjoy - Ed
Ooops! I got it turned upside down:
distance in inches x (25.4 x 3600 / (5280 x 3.5)) divided by the time in seconds = scale mph
When you work out the arithmatic it is
distance in inches x 4.9481 / time in seconds = scale mph
This is for HO scale.
Example - 36 inch flex track crossed in 5 seconds = 36 smph(HO)
Cheers - Ed
36" or three feet divided by five seconds, then that
times 60 would produce 36
I skipped a step or two but our answers are the same
Faron, here’s a link to the one I designed. I don’t know how to do links in this forum, so you might need to copy and paste the link instead.
http://www.heatherandmichael.com/recklessandveiled/trainspeed.xls