SQWIB that helped a great deal...Thanks! I'll have to read it again so alil more can soak in. Its the all the geometry that has me confused. Figuring out the 65.14 square inches on the cooking chamber to firebox opening is confusing. Wished I'd listened alil better in school.
My main problem with my build is what's quoted below, is this where you're getting confused?
Here is where I started double guessing myself, I put the fire box in place and cut some wood to get an idea of what size thermal plate will be needed and checking height to make sure there is enough clearance from the thermal plates to the cooking grid and at the same time making sure there is enough opening from the firebox to the smoke chamber.
The firebox is right at 5.25" from the top of the firebox to the bottom of the smoke chamber I want it exactly where it is.
The top of the firebox and the thermal plate to the bottom of the cooking grid will be 6" and from the top of the cooking grid to the top of the smoker chamber lid will be a little over 8".
My concern is, "will it be enough of an opening to the smoke chamber from the firebox?"
The pit calculator has no way to accept odd shapes, but the Firebox to smoke chamber inlet will be exactly 1/4 of the tank diameter
Hopefully this formula is correct
20" DIAMETER TANK 10" X 10" X 3.1358024 divided by 4 = 78.395, actually that does not apply to sectioning the tank in this matter, but thanks to a fellow builder and his CAD program he came up with my numbers actually being, 61.418, so I am good to go.
Below is an explanation of this from
JIRodriguez at
SMF.
Quote: Figured out where the difference was coming from the formula 3.14xRxR gives you the area of a wedge shaped opening exactly 1/4 of a 20" dia. pipe (like a pizza cut top to bottom & side to side).
But the shape profile is different when you split the pipe with parallel lines every 5". The two areas closest to the center point have a larger area than the two areas on the outside. So you end up with the two middle sections measuring 95.661 in. sq., and the two outside sections measuring 61.418 in. sq.