A sketchup drawing of what we were going for:
It was going to be a bell version of a barrel build with the burn tunnel on top and the bell and exhaust below. Here is a partially transparent illustration.
We built this design in 2013 and it was a complete failure. The fire would not burn properly, too smoky.
It was a design that looked good on paper, but did not work in reality. Sadly, we have given up on it and tore the build down.
The big message here is that
Hot Gases Rise (and they back everything up if you force them to sink).