Hello, SETUP: My question is about calculating the length of a cable wrapped around an elongated cylinder fig. (A). Ive found on-line calculators that will give me that data for a coil around a cylinder fig. (B). http://deepfriedneon.com/tesla_f_calchelix.html however I dont know if thats the same surface area as fig. (C). I did a physical test with a string around a can (D). Made a mark on the can and wrapped the string around two times and cut the string at the same mark were the string started. Then squeezed the can to shape an oval fig. (E). Then rewrapped the same string around the squashed can. The string started and stopped at the same place as on the round can. I guess no surprise that the surface area didnt change. MY QUESTION: But squashing the can fig. (E) and the shape (A) seem to be two different surface areas. How can I calculate the surface area of (C)? GOAL: My ideal would be to make a calculator that I could change the shape profile and get the wrapping calculation as in http://deepfriedneon.com/tesla_f_calchelix.html RELATED QUESTIONS: 1.) Is there a geometric name for fig. A or C? Thanks for and help in this matter. Attachments:

Sander, thanks for the update. Yes the cable thickness is an issue and as you see with the link below so is the gap between the rows. But I could just add a little to the diameter of the cable to compensate. I found this on line but is only for cylinder helix wraps. http://deepfriedneon.com/tesla_f_calchelix.html Should be fun to turn this into a plugin for my CAD program. BTW I'm talking with folks here as well. http://forums.autodesk.com/t5/design-validate-document/coil-profil-or-wrapping-shape/td-p/6499340

Sander, I see your from Lyon. I was close to getting a job there in Lyon but it fell through. I live in LA and was looking forward to living in France, se la vie. BTW - Love your photos

Sander, Thanks for your detailed reply. Stadium as in the shape of a sports stadium, interesting. I knew PI would be involved in this. I have a predetermined length of cable that needs to fit with in a space. Using your formula I can figure the length of one wrap and multiply it to fit the length needed. Yes the gauge of the cable will need to be factored in as well as the pitch of the cable as it wraps, as small as that is. Sander, again that's for your time and knowledge with this problem.

Coil wrapping surface area calculation