# Q&D Scale Speed Estimates

Discussion in 'FAQs' started by billk, Mar 8, 2002.

1. ### billkActive Member

Here's a way to do quick and dirty estimates of your trains speed:

- Pick one of the times from the "seconds" column for your scale
- Measure (or estimate) how far your train goes, in inches, in that amount of time
- Divide that distance by the number at the bottom of the column.

The result is pretty close to the train's speed in MPH. The error for each of the combinations is shown. Once you find a combination that works for you (some of the times are pretty long), you just need to remember the time and the "divide by" number and you can do the math in you head (well, maybe).
2. ### rockislandmikeActive Member

Huh, pretty kewl. I'm sort of a math whiz, so I think I prefer the old calculator method (well, actually, I've set up a quick spreadsheet to calculate scale speed), but still a pretty handy table to have. I clocked one of my fave engines at 9mph last night on my shelf layout from end to end.
3. ### sumpter250multiscale modelbuilder

Arithmatic gives me a headache, but here goes.

60 MPH, is 88 feet/second
30 MPH, is 44 feet/second
15 MPH, is 22 feet/second...... Yeah, it's linear.
so,
in any scale; 60MPH is two "40' " boxcars/second
30MPH is one "40' " boxcar/second
15MPH is one "40' " boxcar/every 2 seconds

I guess that makes 500MPH faster than a speeding bullet.............train.
4. ### roryglasgowActive Member

I once clocked a 2-8-0 Consolidation at 120 MPH on level track!

Of course, that was my old Bachmann...

-Rory
5. ### kettlestackMember

Thanks for the table Bill. I tried several of my HO locos using it.

Results without pulse power:-

3 truck Shay (Bachman) .... 3.2 mph
GP9 (Atheran) ................... 3.0 mph
SW1500 (Athern)............... 3.0 mph
44 tonner (Bachman) ....... 3.0 mph
B30-7 (Bachman) ............. 3.0 mph
4-4-0 "1870's" (IHC) ........ 3.5 mph
2-6-0 Camelback (IHC) .... 3.5 mph
2-8-0 (Bachman) .............. 3.5 mph

Back in '75 I built the TAT IV throttle which has start pulse and variable pulse power. I have yet to test the slow running using this throttle but using it on my N gauge locos I achieved something like 0.2 mph. Of course I wouldn't run locos continually on pulse power. I've heard too much about ruining motors with pulse power although it hasn't happened to me yet.

Errol
6. ### Billybob ReubenNew Member

The best way I've seen to calculate the actual scale speed of a model is with a small hand held timer that I believe is called a "speed chronograph". It is what coaches and trainers use to time the speed of runners over a measured distance. It is also used by horse trainers at race tracks for the same purpose. A friend of mine had one of these he said he found at a sporting goods store in NY for around \$50. He adjusted it to read the speed of his trains over a 1/10 mile distance, i.e., about 6 feet in HO gauge. The readout was instance and as I recall accurate to 1/10 mph. Maybe someone can check around some of the larger sporting goods outlets to see where we can get these timers.