First, I know this is a very old thread. If the mods think it should be moved I'm OK with that, but thought it fit here for continuity.
Thanks for the speed table document. I spent some time last night playing with this. Before I comment / ask questions here is some background: I run Fn3 (large) scale narrow gauge. Mostly steam, some small early switcher diesels. Top speed on these locos is about 25MPH. I am in the early stages of converting to RailPro.
First, I noted that your document suggested that the Start and Top Speeds be set first so they would properly be represented on the speed table. I noted in my testing, that the throttle setting for a slower speed, lets say 5MPH would require 10% throttle after the Start Speed had been set (4.5% in my case), but that same 5MPH would require about 15% without the Start Speed being set first. I understand that this is because RailPro re-assigns 0-100% of throttle to the difference between start and top speeds of actual speed controller.
With the above in mind, I suspected that entries in the speed table are relative to actual controller percentage, not the throttle percentage after Start and Top speeds are set. I decided to make a note of the Start and Top speeds, but set them back to 0% and 100% before running my speed tests. I then reset the Start and Top speeds to their former settings before entering my test results into the table.
I'm sure with mainline locomotives the difference would be minimal, but the test results with my locomotives vary significantly at speeds below 20MPH. At 20MPH and above the difference was insignificant. If you generally run your locomotives above 15MPH, my findings would make little difference.
Now, my problem. Since my locomotive's top speed is 25MPH which is achieved at 90% throttle my table is a very steep curve. In fact, it''s so steep that I can't enter the actual throttle percentage for 20 and 25MPH because the slider at those speeds won't go high enough! So perhaps, the fact that the horizontal scale was not labeled in MPH might indicate that it does not have to be 0 to 100MPH.
Because the curve is so steep, the throttle becomes a bit touchy. Much more responsive than at the default curve, but I think I am forcing the loss of resolution. My goal was to improve chuff sync, which I haven't tested enough to say if I have.
I'm wondering what would happen if instead of MPH, I interpreted the horizontal scale as percent of top speed? That would allow a much shallower curve, but I don't know how this would effect the chuff sync. Thoughts?
A note on speed testing. Since I run point-to-point, with no circle, I opted to build a speedometer car from a cheap bike computer. When I was reading the Speed Table Guide it took me some time to realize you just kept running the loco around the circle and timed it each time it traversed the circuit. Leaving the loco running while popping into the speed table had me scratching my head. My loco would reach EOT and crash before I got back to the throttle page!
