While most OGR members know this calculation, or a better one, already, I thought I would share this for anyone who hasn't gotten around to doing the math themselves.
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I cheat. Scale miles per hour is whatever my DCS remote (or iPhone if I’m running WiFi) says it is. 😉
Curt
juniata guy posted:I cheat. Scale miles per hour is whatever my DCS remote (or iPhone if I’m running WiFi) says it is. 😉
Curt
Those of us running Legacy don't have that luxury. They don't show you miles per hour.
To my knowledge a "speedometer car" has only occasionally been offered, and, even more surprisingly, a reasonably scale dynamometer car (perfect place to put the 1:48 speedometer) has never been offered in the 3RO format, functional or not.
This should not be a mystery or an arithmetic "problem"; a car or, maybe better, a pair of "speed trap" sensors on the layout. (Didn't Lionel offer...?) This stuff should be common and cheap. It's not. We keep pencil-whipping it. Why?
D500 posted:To my knowledge a "speedometer car" has only occasionally been offered, and, even more surprisingly, a reasonably scale dynamometer car (perfect place to put the 1:48 speedometer) has never been offered in the 3RO format, functional or not.
This should not be a mystery or an arithmetic "problem"; a car or, maybe better, a pair of "speed trap" sensors on the layout. (Didn't Lionel offer...?) This stuff should be common and cheap. It's not. We keep pencil-whipping it. Why?
I couldn't agree more! There is a Youtuber named Bobots trains who built a really nice track speedometer from scratch. And I have seen one offered commercially online but it was crazy expensive. Since all Legacy engines supposedly run the same speed at the same speed step setting it really should be included on the Legacy controller screen. I think someone once said MTH has a patent on it or something like that. But it really should be available.
I use this one when I have the need. This forum is the only place I could have gotten it. I know this, when you get up to speed step 144+, that train is “movin” 
Then there’s this accessory in the “For Sale” thread. Have no idea about how it works, accuracy or reliability.
pedestrian-walkover-with-scale-speed-sensor-6-14082/
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There's an even older formula:
Measure the number of inches traveled in 2.5 seconds. That's your scale MPH.
Learned it from a 1960's era book (well, old enough to talk about ASTRAC as a command-control system). Did the math and it matches up.
---PCJ
Precisely how calculating a unit of measure is patentable... eludes me at least.
Severn posted:Precisely how calculating a unit of measure is patentable... eludes me at least.
Right? Crazy
RailRide posted:There's an even older formula:
Measure the number of inches traveled in 2.5 seconds. That's your scale MPH.
Learned it from a 1960's era book (well, old enough to talk about ASTRAC as a command-control system). Did the math and it matches up.
---PCJ
That's a good approximation, but to be exact it would be 2.73 seconds
