Ahh...OK the pics give me a better idea of what you're dealing with. I was calculating the area of a flat, 2-dimensional end - like if you cut the bell-end of your tank off square and flat...which is what I did on my reverse flow build. Then I welded on an end cap. Made the calculations easier since everything was 2-dimensional.
Here's a couple pics to show you what I mean:
View attachment 699099
View attachment 699100
I'll assume your calculations are correct, and that your throat opening is indeed too big. IMO, you can fix that one of 2 ways.
First, you could simply make the opening in the firebox come out to the recommended area of about 52 sq. inches. Once it's welded in place on the tank, the larger opening is covered, and the effective airflow in the throat is correct. Only thing is, since I didn't do my RF build that way, I don't know how that extra metal in the end of the cook chamber might affect air flow...if I'm making sense.
Second, you could simply cut the remainder of the bell end off that tank like I did mine, and make if flat and square. This would make your overall length a little smaller, but wouldn't really change the usable cooking area by much. With a flat end, the area calculations become much easier to figure. Only thing is, it would require a piece of plate to make the end cap. But if your buying some plate to build your firebox out of, you could have enough steel left for that.
I'm not sure if any of that makes sense. If not, holler back and we'll figure it out.
And BTW, if you're interested, here's the link to the RF build I'm talking about. Maybe there are some ideas there that might help.
Howdy SMF Brothers and Sisters! I started a RF patio smoker build several months ago...and kept meaning to start a build thread here. So I'm finally getting around to doing that! I started with this propane tank. It's 5/16" thick, and 24" diameter by almost 11 feet long. I plasma-cut the...
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