Bear with me here.... I was helping spoon on a PM because he wrote me..... Now I'm transferring this stuff here for everyone to help him out.... It is a little disjointed but all the information is here.... I think.... click on images to enlarge...
stack vol= 589.05
FB air intake= 34.65
FB and CC opening= 138.60
area under RF plate= 138.60
http://www.1728.org/circsect.htm
There is my calculator.... It's based on the size of the CC...... the circle calculator is used for the FB/CC opening and area under the RF plate and area at the end of the RF plate and the width of the RF plate.....
Try cranking numbers using my stuff and see what you come up with.....
150 x 231 = 34650 YEP... perfect...... so now you multiply that number x .017 and .004 and .001 then figure the other crap.... and use the circle calc....
The FB can be as big as you want.... 12,000 cubic inches or 20,000 cubic inches and it won't change a thing.... just more room for wood and ashes and a bigger volume for heated air.... and more uniform heat......
Click the box ..... Radius and Segment Height ED...... then keep changing the segment height ED until you come up with something close to 138.6 ..... that is the height of the AB line for the diameter of the CC..... and the height for the FB cut-out..... and the width of the RF plate is chord AB .......
You can kind of follow the numbers on my calculator sheet and see where everything fits.....
The green area (Circle Two) is a
segment.
The area of a segment equals
Sector Area Minus Triangle AOB Area
24" Diameter and 12" Radius.....
12" radius and 8.5" segment height = 143.4 segment area.... good enough for trying to get 138.6 segment area.....
Now, when cutting this stuff out, if the FB top is 1/4" and the CC is 1/4"... allow for that so the "INSIDE" measurement is 8.5".....