I second the idea of the full RMH as a wonderful final stage of the series of projects!
I'd consider a progression, pocket rocket demo, followed by rocket stove demo (complete with hot food to be eaten!) and moving on in logical stages until they are able to build the full rock mass heater. Tons of cool stuff to learn! A great idea
You can make the upper barrel a bell by extending the chimney pipe down into the barrel and make it much more efficient, but you might not notice in that short of time.
Nick DePuy wrote:Awesome! One last question, has anyone burned 'Paper Bricks' in their RMH? In case you are not familiar, you soak the paper in water, blend (if you want-not necessary) and compress into 'bricks' using whatever form you want. (A friend of mine used a pvc pipe with holes drilled in it, a ram and a couple bowling balls.) I work in an office that generates HUGE amounts of shredded paper so I thought this might be a free source of fuel. Thanks!
I've not tried it myself, but I've seen a few YouTube videos on it. Time seemed to me as the biggest negative factor, and for me time has more value than buying a cord of wood. Even if I have to split the wood, it seems faster and easier to me. But you may feel differently about that, so yes, try it and let us know what you think! If you could rig up some kind of ramming system that might speed the process.
In terms of paper, the question I would have is what chemicals are in the paper? Black and white paper may be OK, whereas four color printed paper maybe not so good. You may want to look into that, and find out what the chemicals break down into when burning at various temperatures.