I've been searching all over this forum, and my eyes are getting tired...I've seen several posts stating that Feldon's Calculator is flawed. So, I just want to know before I begin my build. I have an old propane tank that is 36" I.D. and it was about 8' long, and 1/2" thick. So we cut it in half to make two smokers out of it for my brother and I. So my half is about 45" to the weld seam where the round end cap is welded on, and the end cap is about 12" tall (with my calculations, the end cap amounts to around 4 cubic feet ??) So the straight section that's 45" long amounts to 45,781 cu. inches, or around 26.5 cu. feet. With the end cap added, I think I'll be around 52,693 cu. inches or about 30.5 cu. feet. I'm not 100% sure of my calculations, but I think it's close. Any info about my cooking chamber opening size (circle segment height), firebox size etc. would be greatly appreciated! The calculator says around 24" x 24" x 32" for the firebox ??And around 32" of 6" pipe for the chimney. Also, what are everyone's thoughts about the chimney being down close to the cooking surface? How close? Should the end at the grate surface be cut at an angle? Does that make a difference? How about the height of the cooking surface from the RF plate? Any hard and fast rules on that? Like I said, I'm sure this stuff has been covered, but I'm just not finding the posts I need...I haven't really started yet, just wanted some thoughts! Thank you all for your time!