I often read of Scale Miles per Hour, how is time Scaled? Does one minute equal 87 Scale minutes in HO, and 48 Scale minutes in O?
Speed being a factor of distance traveled in a given amount of time, would require a standard for Scale Time, if a Scale Speed is to be derived. So what is the formula for scaling Time?
Doug
“Scale Time” is usually referred to as using a “fast clock”. Fast clocks ususally run at a 2:1, 3:1, 4;1 or 6:1 ratio. So at 2;1, 4 real hours = 8 model hours, at 3:1, 4 real hours = 12 model hours, at 4:1, 3 real hours = 12 model hours and at 6:1, 4 real hours = 24 model hours.
It is more related to the scale of compression of the length of your run than to the scale of the trains.
Its basically an artificial way of covering a certain portion of the day in a fixed time so you can operate by timetable or sequence. So if you want to operate your railroad for 3 hours and want that to represent 1/2 a day, you could use 4:1 fast time so the 3 hours models 12 hours. Etc.
A lot of people wrongly blame it for putting “pressure” on the operating session. If you are going to operate 20 trains in a 3 hour session, it really doesn’t matter what clock you use, you are still going to operate 20 trains in a 3 hour session. The real problem is that either the schedules are bad (the owner’s problem) or they are trying to operate too many trains (the owner’s problem).
For calculating Scale Speed, is a fast clock used? if so 2:1, 6:1 or which other? Or is Scale speed calculated using True time and scale distances? I am trying to understand just how Scale Speed is calculated.
Thank You,
Doug
For calculating scale speed, you use real time and scale distance. For instance, a scale mile in HO is about 60 feet, 8 inches. Using the formula 60 / T x M, 60 is the number of minutes in an hour, T is the time it takes to run the distance in minutes and M is the distance expressed as a percentage of the SCALE mile. If your train ran one scale mile in 2 minutes, it would be 60 / 2 x 1 = 30 Scale Miles per Hour. If you don’t have a scale mile to time your trains, you can use whatever percentage of a mile to figure it out. Also, it will be handier to time in seconds, so you can substitute the number of seconds in an hour (3600) in the place of 60 to calculate with seconds.
Doug, time doesn’t scale. You scale distance, and then measure the time it takes to cover that distance. A scale mile in HO, for instance, is 60.62 real feet. If your train covers that distance in 1 real minute, it is going 60 scale mph. Don’t confuse “fast time” with anything like “scale” time. There ain’t no sech thing. The fast clock is used strictly to give the illusion of time passed over our greatly shortened model distances.
The formula for calculating scale speed by clocking a train over a given distance (say, 3 feet) is:
(D/T)3600/5280R=smph
where: D=the distance covered in actual feet, T=the time in seconds required to cover it, and R= the scale ratio (87.1 for HO, 160 for N, 48 for O, etc.)
Thus, if your HO train covers 3 feet in 3.4 seconds, it would be going 52.4 scale MPH. An N scale train covering the same distance in the same time, would be going 96.26 scale MPH!
If you like, contact me off-forum (email) and I’ll send you an Excel spreadsheet I created that provides a table of times vs. speeds for any scale, over any distance you choose.
James and Gary,
Thank You, I was familiarn with scaling distance, I wasn’t sure if speed was calculated with real time or some other value.
Thank You Again,
Doug
Scale speed in real-time running situations can be approximated fairly closely by counting the number of 50’ cars that pass a fixed point in 3 seconds. This works in any scale because counting the scale cars at 50’ puts it in the proper distance perspective. Here is the formula:
60 MPH - 5.5 cars; 50 MPH - 4.5 cars; 40 MPH - 3.5 cars; 30 MPH - 2.5 cars; 20 MPH - 1.5 cars; 10 MPH - 1.0 cars; 5 MPH - 0.5 cars
Hope this is helpful. It certainly helps me while in an ops situation.
Ron