half moon calculation question

[Bagman]

Good morning. Have built a traditional offset in the past, and am currently building a RF smoker. I have a question regarding the calculation of the size of the firebox to CC opening. The calculator states 10.9 inches for half moon or 46.66 sq inches. I suck in math, but common sense tells me if i make the top straight opening 10.9 inches, and just carve out a half moon so to speak, I dont see how that can equal 46.66 sq inches. I am thinking I should have paid a tad more attention in geometry class. Any advice would be greatly appreciated.

[Rodcrafter]

Here is a link to see if this will help you, just fill in the blanks and see how this goes.
http://www.handymath.com/cgi-bin/arc18.cgi?submit=Entry

One other point, square inches are just multiplying the 2 dimensions. Your question 10.9" x 5" if both lines were parallel would equal 54.5. So since one is on a radius it would be cutting off some of the area. So as a quick reference you can use this square method knowing it will get you close. This is the best I could do with out knowing the diameter of you CC.

jm2cw

[Bagman]

Thank you for the link and the help. I just took a sheet of paper and made 1" squares on it and drew it out to get the proper square inch dimensions. I guess in my mind i needed to physically see it LOL. Since this is my first reverse flow build, I just want to make sure everything is close to perfect. Thanks again!

[Clover Ridge Smokers]

You can also use a trapezoid instead of a half moon. Much easier to calculate