I know this set up looks ridiculous. There is a heat riser under the barrell and a mass. Aside from losing the double burn isn't this practical for burning huge logs of that's all you have? The smoke comes out cold but not as clean. Please share your thoughts.
Neat. Do you know about batch rockets? They handle larger wood.
As to this design, if you ran the exhaust from this barrel stove into an already burning rocket stove fire, you might burn off that dirtiness you mentioned, and still capture the heat from less processed logs.
The concern I have about running dirty smoke through a "conventional" riser/barrel/mass set up is the build up of unburned but burnable matter throughout the passage ways.
Thank you for sharing, could be a conversation starter.
How big are the "huge logs"? As mentioned, a batch box can burn larger wood than a J-tube can.
I see this setup as a chimney fire waiting to happen - the incomplete combustion is making some amount of creosote, which will all be condensing on the inner surfaces of the mass. It will wait for the coldest time of winter when the stove is firing hardest, and the first bit of creosote-coated mass liner will get to combustion temperature... then it's history.