The mathemathics of cone design

[Anders Troberg]

I've been away from jets for a while due to other commitments, but now I'm back with a question I'm sure someone here can answer.

My problem is that my pet rat Ambrose (The guys are all named after Mexican revolutionaries, due to their large whiskers. It was ither that or eighties porn stars or dictators...) can't leave a small sore alone. I've previously made "lamp shades" for my rats after surgeries. Rats are amazing at getting out of ordinary designs in 3 seconds, but my design sits safely and comfortably. The problem is that I've been cutting the cones by guessing, which means many tries, with uneven results.

Now, (cut off) cones are a pretty standard part of pulse jets, and I'm sure I've seen someone here who has the mathematics of them, so I can just calculate from the wanted final measurements and get it right on the first cut. Someone who has the needed formulas to design a cone from a flat sheet?

[PyroJoe]

There are several in the "Tools and Construction" area.
Here is one I put together:

viewtopic.php?f=7&t=5901

[Anders Troberg]

Thanks!

I managed to do it myself, with a method quite similar to that one, although I used a slightly more convoluted method to find the angle.