Minimum radius for American Flyer

[Comet]

Can anyone tell me the minimum radius required for American Flyer "S" gauge, both steam and 6 axle units like the PAs?
Thanks,
Bill

[BoxcabE50]

I believe it could be had in two different sizes. A 19 inch radius. And then a 54" diameter circle (27 inch radius.)

Hopefully, I am correct. . I hope somebody will tell us that my memory has not failed to badly. redface.gif

Boxcab E50