How can I calculate the throat opening for my new smoker build ? I am using a 22 inch diameter , 48 inch long,60 gallon air tank for my firebox. 24 inch diameter, 60 inch long cook chamber. This is going to be reverse flow, installed on a trailer, and both tanks will be horizontal. I am NOT connecting the tanks end to end, I want to connect the firebox at a 90 degree angle off the back of one of the cook chamber ends. Is there a way to calculate this weird throat opening?