I'm not sure what many of you use to figure out your up scaling on rockets, but I've been doing mine in Auto-cad based on tube size. Say, if I want to turn a Baby Bertha into a BT 80 size model, I'd have to go through the whole trial and error CAD scaling process because I don't know the formula for skewing things to scale. There is a way and I'll figure that out some day. But tonight I sat here and meticulously scaled every standard low powered tube from BT 20 to BT 80. I did this because I often have to scale for myself and LW, and now and again some random request from someone on the forum.
SO...for anyone that uses Auto-cad to draw their rockets, and want to know the formulas for upsizing your favert kit, see the attached PDF file. This is going to make up scaling a breeze from now on.