# Model Railway Speed Gauge

Discussion in 'Tips & Tricks' started by kiwi1942, Aug 4, 2008.

1. ### kiwi1942New Member

HI
I am wondering if the is a FORMULA to calculate the speed of a model Railway

3. ### kiwi1942New Member

Gauge Speed

Thanks for this

looks like I have to go back to school
4. ### cidchaseActive Member

If it's HO:

measure the distance in inches that your train travels in 5 seconds.
This is the same as the scale speed in MPH (about 1% error).

If it's N, THEN you have to go back to school:mrgreen::mrgreen:
5. ### kiwi1942New Member

HO Speed

Yes indeed its HO

thought we were smart while at a EXPO when someone asked us what was the REAL SPEED, we omitted we had no idea of hand, so hence here or somewhere looking around, then we decided to do a test ourselves as follows

10 fingars span = 9 inches x 10 = 90 inches,
taking 12.14 seconds, not sure where to go from here

inches into miles x seconds into hrs, now looking for the calculator

90 / 63360(inches in mile) = 0.00142045e x 60 x 60 = 3600(seconds per hr), on my calculator this reads 5.11362, ??? mph or s there mre to add, like 1.87 scale

I AM NOW REALLY CONFUSED

6. ### nolatronMember

Or just get one of these
7. ### kiwi1942New Member

So I am nearly right with my sums then or so far away it dont matter, sorry to say can not afford one of them for now
8. ### cidchaseActive Member

9" in 12.14 s =
3.71 " in 5 s (9*5/12.14)
or
3.71 scalemph (estimated by the 5 second rule)
or
3.67 scalemph (true value)

How close did you measure the 12.14 seconds?:mrgreen::mrgreen: BTW, I don't see the 12.14 seconds in your calculation. And yes, you can multiply the true speed by 87.1 to get the scale speed. The distance is scaled, but the time is always constant.
9. ### cidchaseActive Member

Again, with your second hand or stop watch, measure the distance (in inches) traveled in 5 seconds (easy way).

If you travel 36" in 5 sec, you are going 36 scale mph (small error).

The true value is 36 X 87.1 / 88 or 35.63. This error (1.02%) might be less than you can really measure with your second hand!! :mrgreen::mrgreen: