[Cob] rocket stove

[Amanda Peck]

"more natural" might be firebrick.

But the burn tunnel and the heat riser get VERY hot.  They need to to push 
air through that "up to" 40 feet of bench.  So materials need to be chosen 
to survive the heat without cracking.

There are two barrels that one sees in pictures.  The first is where you put 
your wood.  No reason not to cover, the sides, I'd guess, but the inside 
needs to be bump-proof, and have a fitted top that will allow only a certain 
amount of air into the combustion area.  with the other barrel--the 55 
gallon drum--the top can be used to boil water--some sort of metal sounds 
like a good idea if you want to do that.

Somewhere in there there comes a point where smooth insides are good, if I 
read what "IANTO SAYS" correctly (sorry, old joke--in philosophy sometimes 
it came out "Wittgenstein says" and nothing more needed to be--might have 
said more about the speaker's not having a clue than Wittgenstein's 
infallibility). Metal has its uses for that purpose as well.

The bread ovens are different.  Instead of a burn tunnel, there's a fire 
built on the floor of the oven.  It MIGHT get the oven walls to 700 degrees 
F.  but not twice that or more.  The smoke coming out the chimney is 
basically waste product, and under those circumstances trying to force it 
into a long horizontal run wouldn't work--too much creosote and besides it's 
not moving fast enough.

Lisa asks:
I'm wondering about the idea of instead of using metal barrels if it would 
be possible to make those components out of cob? I guess it would be similar 
to a cob oven.
could it take the temperatures that exist in a rocket stove?

what should I be aware of if I went that direction.

Lisa