I'm asking the same question over Papermodelers too. Basically I need to find out the heights and diameters of a series of truncated cones (the engine bells for the 1/48th Saturn V) so I can make special tools for repeatable results when assembling.

Go to this page Near the middle is a link for an Excel spreadsheet that will show the inner radius, outer radius, and arc angle for building a truncated cone based on dimensions you enter. Glenn

What I really need to be able to do is find the lengths of the arc segments. I could do it all with a caliper and some math, along with a little guess work. But then if there are any printing errors they will creep into the answer. And they will always compound. Errors never seem to cancel each other out. In the past I have used this http://www.pulserate.com/