Although I've never made one, I think I'll try as a test. Any one have any experience using this method?
Looks interesting. They use something similar here in the Middle East to bake bread in. It is an earthen oven much like that one but completely domed. I'll try to get some pictures. They seem to work very well.
I think theres something real similar to that on 'journey to forever' site. I guess it creates a draft in such a way as to be a lot more efficient in its use of fuel.