Tom Tee posted:A numbered turnout is the ratio of the degrees of frog angle. A radius is a constant arc of curvature..
Oil and Water.
Well, yes, but I think a little emulsification is in order.
The Curved Closure Rail has a radius between its two tangent portions; this radius will generally vary slightly depending on how long the tangent sections at frog and swing ends are, but generalizations can be made. The data sheet in an Old Pullman catalogue shows their #5 0 scale turnout having a nominal 52 inch radius; an Atlas #5 might vary a bit from that.
The Standard Drawing for a UP #7 [ as low as they go ] turnout shows a [ c/l ] radius of 353' 10 13/16".
If a locomotive, especially lwb steam, has an advertised minimum radius of n, one would not purchase a turnout with an effective radius less than n, and [ Opinion ] it would be good practice, space permitting, to go at least one number higher than the minimum where possible.
With best regards,
SZ
Edited to add: I used lwb as an abbreviation for long wheelbase, but from memory wasn't LMB Models the tradename for the 0 scale of Leonard Blum of Blum's Hobby House ? He had some Really Nice Stuff in his personal collection.......
