isn't the same principal as your rocket mass heaters??
Not really, more like a water jacket around a wood burner. Kelly kettles have been around a long time "first produced the product in Ireland in the early 1900s".
RMH wants to get gasses as hot as possible for complete burn of everything so you insulate the burn chamber. This is taking heat off the fire right away.
In a similar vein to the can stove above is the garlington wood gasification stove It's a "batch-loaded, inverted down-draft gassifier" that is also DIY and tin can based. It's a handy little stove i use in the backcountry, I use shavings from wax/sawdust cubes molded in cardboard eggcartons as a starter.
These can stoves can really lighten your pack and in appropriate environments can be much lower impact (and way less expensive!) than backpacking stoves. Watch you don't burn the world down accidentally.
The kelly kettle is heavy, but i like the stainless version for beach camping with small open sailboats.
Devon, I built a working garlington just by reading through the description on that page and looking at the pics. It's pretty easy and essentially free so you can play around until you get it working right.
The batch load firing means you need to be pretty organized for cooking and have some simple foods to prepare.
It's not a perfect stove and not as convenient as firing up the old whisperlite, but once you get used to living with it it really grows on you. For ultralight backpacking it's great.