I have an old New York Central specification sheet for the ALCO RS-3 that lists the sharpest curve that the engine could operate on was 21 degrees. What is the radius in feet for a 21-degree curve? Looking to make sure that I have something akin to realism in next rebuild of HO layout.
I can't answer your question directly, I'll say that up front. It seems to me though, that the distance of a curve in feet versus degrees would change with the elevation of the track and track speed. A 21° curve would be shorter if the allowed speed was 30mph as opposed to 60mph or if the track was banked rather than flat.
I had the answer to my question in my home library. One of my "treasures" is a Fairbanks-Morse brochure entitled, "The Lackawanna Story." Brochure was a sales piece for the F-M Train Master, which was not a small locomotive (around 67 feet over couplers) for the time. F-M gave the following specs for curvature:
Minimum radius of curvature = 191' (30 degrees)
Minimum radius of curvatuer, locomotive coupled to AAR 40'6" freight car = 212' (27 degrees)
With HO-scale, 212' radius is about 29 inches. Next train table will have to be somewhat bigger. My current layout has most curves with 22 or 24 inch radii.
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