ChuckAuger

My Feedback: (12)

Can somebody point me in the right direction??

I need the formula to determine the angle of the circle sector to be removed from a circle to make a cone of a certain height.

That is to say, if you have a circle and remove a pizza-slice-shaped sector, then join the edges back together, you will get a cone.

I know the diameter of the base of the finished cone, and the height of the finished cone I wish to construct. What I need is the formula to determine the central angle of the circle sector that will need to be removed to make the circle become a cone.

I tried breaking the cone into a right triangle, solving for the hypotenuse, and using this as the radius of the circle I start with. Then using the ratio of the diameter of the circle to the diameter of the base of the cone to come up with the central angle of the sector to be removed (result of the ratio X 360 to get degrees, then subtracted from 360 to get the resulting central angle)

I'm doing something wrong, somewhere...

bentgear

Chuck, have you got Excel, if so PM me an address I will send you a spreadsheet that covers it...................

Ed M.

ChuckAuger

My Feedback: (12)

Thanks,

I think I have figured it out, I need to make my final ratio the circumferences of the circle and the base of the cone, but I'd sure take a spreadsheet!

bentgear

Tried the email link on here but I can't add an attachment.
Ed M.

ChuckAuger

My Feedback: (12)

I pm'd ya

bentgear

It should be in your inbox.........ed

Tall Paul

From a previous discussion here:
http://www.rcuniverse.com/forum/Desi...1801795/tm.htm

bentgear

Tall Paul, thanks, that may be better than the spreadsheet for my purposes at times.

Ed M.

ChuckAuger

My Feedback: (12)

Well Ed, your spreadsheet worked like a charm (looks like we might build similar things..) And it actually confirmed my calculations (the ratio of the circumferences is the same as the ratio of the radii..duh) so I was doing it right.

I built a scale model based on my original calculations, and it was spot on. Something else was causing the problem, but now at least I have a second opinion to back me up.

And I went ahead and downloaded the cone program Tall Paul pointed to that DickeyBird found. I'll play with that, too!!

Thanks, guys. I really appreciate this help.

DICKEYBIRD

Hey Jeff, play around with Cone some. It's an AMAZING little bit of freeware. You don' be needin' anymo' of that mathamaniacal type of thinkin' after using it awhile! I wish that kind of stuff was available way back when I was playing around with tuned pipes on 2 stroke dirt bikes & stuff!