Try the link below if the one mentioned in the previous posting here
doesn't get you what you're looking for. I'm thinking Jason has made
some changes to his site.
http://www.cobmob.com.au/Cob/Home.html
Look for the Rocket Mass Heater Jason built. I'm planning to use some
of his ideas in the one I'm now building and will report back to the
group with my progress ... and lessons learned.