I am new here.

Hello all my name is Malcom and thank you for letting me be a part of your community. I have a few things that I would like to ask concerning rocket stoves. My first question is, the purpose of the J is to create turbulence in the exhaust stream remixing unburnt fule? My second question is, could I just have a fire box with a straight pipe that had plates in it that created turbulence causing the exhaust to reburn? Thank you for you time.

Yes, combustion will be remarkably complete inside the tunnel, mainly because the flames are burning sideways. This will cause lots of turbulence and on top of that, the highest temperatures do occur in a confined space. At the same time there should be enough, but not too much, fresh preheated air at that precise spot. The whole process is dependent on pretty high gas velocity.

And no, just a straight pipe on top of a combustion chamber won't work even with turbulators inside. Whatever you do, either the turbulence isn't enough, the temperature is too low, not enough preheated air available or the gas velocity is too high or low. Complete combustion in a vertical pipe is near impossible, let alone an uninsulated one. In my opinion, that could be because hot air wants to rise very fast, racing through the vertical duct. In short, this horizontal tunnel will do the trick!

I will be back with more question's

I have been reading a lot on the idea of rocket mass heaters, even though I do not want to build a rocket mass heater. I do take the information and try to apply it to my cause which is to make myself a water heater that does not cost a arm and two legs to make or buy. I am most definitely not going to go out and buy a wood gasification boiler for the 1000's of dollars it cost's, it just does not make common since to do that, plus they do not heat the water efficiently as I would like them to. Sure they burn the wood down to a very fine ash but you are still wasting that hot gas out the flue. I do not claim to be the brightest crayon in the box but i do understand common sense. If I have a question that I ask and it has already been answered some where here please feel free to post a link to it because even though there is a wealth of info here I do not have a 100 years to sort through everything here. From my experience with the search bars with form's you hardly get what you are asking for with them. Thank you all for your time.