RE: Conical primary length formula

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Godfrey Loudner" <ggreen-at-gwtc-dot-net> 

Hello Michael

That formula could just as well have been made for the length of the
filament
along which the copper tube is in contact with the imaginary cone. This
would
have been a more accurate estimator of the tube length, but the length of
the
filament along the center of the tube would give a little extra to work
with.

I derived the formula by applying the calculus formula for the length of an
arc
to the parametric equations for an evenly spaced filament that spirals up
the
cone. Then one uses trigonometry to adapt the filament formula to a copper
tube.

Godfrey Loudner

 >Thanks a bunch for that formula!  Thanks also for the jpeg graphic
 >of it off-list--what do you think of making it available somewhere (on
 >this site or maybe hot-streamer, if that's possible?) in case
 >someone would be interested?  (It's much easier to see it when the
 >formula is written out and there's a labeled picture!)  BTW, where
 >did you get the formula?

 >Michael Johnson