The heat is on the bottom on the side of the cooker, not underneath the cooking chamber. The Stumps GF 223 design is an insulated gravity feed offset, essentially. The 5x7 steel chute going down the side will first have a chimney of lit lump dumped in from the top of the chute, which will land on a removable grate near the bottom of the charcoal chute in the heavy steel firebox area. A removable ash box will be located directly under the firegrate. Unlit lump with be loaded in on top of the lit in the charcoal chute, and an airtight lid on top of the chute on top of the cooker will be closed and latched to stop air flow from the top of the charcoal column. Air enters the firebox at the bottom of the charcoal chute through a 2-inch ball valve that will be in a door to the firebox there at the bottom of the charcoal chute. The grated opening seen inside the cooking chamber channels heat from the firebox at the bottom of the charcoal chute into the cooking chamber. The actual fire is burning at the bottom of the charcoal chute a few inches below the heat entry opening into the cooking chamber.
As the fire burns at the firebox level at the bottom of the charcoal chute, the ash and small coals fall through the firegrate into the removeable ash box and the unburned fuel will gradually feed the fire, thus the GF or Gravity Feed designation. There will be probably two heat shields between the entry into the cooking chamber and the bottom shelf. The bottom of the inside of the cooking chamber where you see what looks like a big X is where he created the positive drain so that drippings and grease would flow toward the drain pipe rather than just side in the bottom of the cooker.
Robert hangs out on a Canadian BBQ board on which many of the members have built or are building these beasts, and results they're seeing are very impressive. One friend of ours here in Broken Arrow built one taller than ours but not quite as wide, and is seeing 9 to 11 hour extremely steady cooks on one chute of lump. The units are insulated with 1500 degree insulation.
I think that why Robert wanted to build this Stumps clone - so he could sleep longer instead of feeding logs to the Fat 50 quite so often through the night. :roll: Now granted, it isn't a REAL Stumps cooker, but through this project he got to learn how to weld, which was something that he wanted to do for a long time anyway. And, hey, once he's through, I have a new toy to cook on, not to mention a husband who knows how to weld!
Oh, and Clint, don't get that coffee mug just yet. Wait until she's finished, when she has her dark garnet red metal-flake paint, subtle chrome flames, diamond plate door, and chrome Peterbilt turn-back stack. THEN she'll be ready for her final photo shoot. :wink:
Keri C