Here's what I've got:
[url=http://feldoncentral.com/bbqcalculator.html?cc=0,0,80,0,0,0,18480.00,6160.00&fb=19,18,18,0,0,6156.00,6160.00,99.9&ch=4,307.80,24.51&fi=0,0,4,18.47,1.47&fc=7.92,11.20,49.25]Link to BBQ Pit Calculator[/url]
So if I multiply the opening area by 1.5, I get 73 7/8 sq in.
The diameter of the tank is 18 3/4", so the segment height will be 5 7/8" which will give me an area of 73.991.
Am I on the right track with this?
The gap for the reverse flow plate on the other end will also be 5 7/8", no?