Hi all have built a 3'x6' oval to run but I think that with the space I have it could be better used with a 1' wide shelf layout that could extend 8' along one wall and 12' around the corner instead of a circle on a table that knocks out 25% of my family room. I then thought that this shelf could be 2 or even 3 spaced out 12 to 14 inches vertically {got this from MR article} and have a functioning railway with several stops, {ambitious ain't he} but looking into a helix is a dissuading subject. Would like to know your experiences both positive and negative to plan mine ie rad, grad, laps and spacing [ have visited the calculator but you can input any numbers you want to make it work, but is it practicable} You feedback will be appreciated. regards: Johnny

The factors for your helix are vertical spacing between laps, radius and grade. Laps will depend on the vertical spacing between main layout sections. Assume you want a 3" climb per lap and a 2% grade maximum. Each lap will be 3"/2% (3/.02) or 150" long. Divide by pi (22/7) and this is nearly 48" diameter. You can cut this down with a steeper grade and/or less climb per lap. 3" gives you a bit of room to put a finger or two around the train and 3/" or so for track, roadbed and sub-roadbed.

The other thing you can do is make a oblong helix if can't afford all the space of a circle. then you could use a smaller radius to get the same elevation. It's just a trade of one dimension for another.

Have you looked in Armstrong's book - Track Planning for Realistic Operations? What radius you are looking at is contingent on inches of seperation between levels; 2 1/2 inches of seperation will be a 2.1 grade with an 18 inch radius; 20 inch radius with the same seperation will give you a 1.9 grade.