I may not be the one to comment on this. I watch the two fellow develop the Drizzler and when they went to the open top, I bailed out. I will say what everyone else is saying-- dry fuel, dry fuel, dry fuel. In the video where you said you could not keep it flaring, when the blue flame went out you could see a cone shape cloud. To me that is moisture. When your woodgas production slows down then it can’t overcome the moisture that is in the gas and the flame goes out. My guess on what is happening is— you start out with ? percent moisture. The closer you get to the center of a piece of wood the higher percent you get of moisture. ( when wood dries, unless forced, it dries starting on the out side and goes to the center, the center holding moisture the longest.) So if you start the pyrolysis process, the material gives up the correct amount of gases to give you a flare. Then as you get to the center of the chip pieces, you get into the higher moisture and that higher percent of moisture over rides your gas.
Bob, comments about charcoal base are good. The only thing is-- we all run will nozzles feeding air into the combustion area which is between the wood and the charcoal. We use the height of those nozzles to tell us how high the charcoal has to be. I would suggest making charcoal out side the gasifier and filling the bottom of the gasifier with it but I don’t know with out nozzles how high you have to go
Keep on working; the answer will come with-- in time TomC