Thomas Schuessler

Thank you all for your help.  I have insulated pipe for the outside chimney, just needed to get an immediate solution up for now. The insulated pipe is heavy and I will need to put in some support for that weight that I haven't time for just yet. As for the top gap and side gap, I will be looking into those issues as soon as I can.  Life and too many projects needing attention slows progress on all of the projects.  At this time, the stove does draw and we have been adding cob to the firebox as I have time. I will next be concentrating on the mass bench next, and will also be able to pry off the barrel lid and see what's what in there. We are able to achieve about 500-600°F on the barrel lid after about 1-2 hrs of burning. The stove does draw, but not enough to truly "rocket", and without the mass for heat storage, we have to keep a fire burning to keep getting heat, so nit achieving the really high barrel temps is kind of helpful as we are not cooking ourselves out of the house.  Once I have the mass for heat storage, then improvement to chimney and barrel will become more critical.
Thanks to all your advice, I at least know where to look and what to fix! The fixes seem to be relatively simple, and I will continue to update this thread as I work to finish and improve this build.  I am excited to build my second heater in my shop now that I have made my mistakes and know what do better the second time.

My top gap is 2".  No idea what my side gap is, but it is big.  I have my half brick riser inside the barrel and nothing else.  I had never come across any mention of the side gap being critical.

Since we have achieved rocket effect we have started adding the cob aroun the fire box and barrel.

Ok. So I went and extended my chimney another 5' up past the roof where I will want it permanently, and now am getting more draw and heat and am finally getting some"rocket" effect!

Once again, temporary set up for fire box testing purposes.

I currently have temporary  pipes hooked up for exhaust.  There will be a mass bench along the wall that I will run the pipe through.

Finally got a semi successful burn.  Had to add fire brick inside my burn tunnel to get my CSA down to that of my 6" pipe. Then put 4 ft of vertical pipe after exiting the wall to add draw.  I burned in the box for about 2hrs, and never achieved "rocket" only reached a max barrel temp of about 350°F.  Hoping that adding my cob around the box and barrel will help, but am thinking that better insulated chimney in the barrel might be key as you say, and then adding height to chimney and barrel if the insulation isn't enough.

My plan has been to use 6" pipe for the exhaust, but after my first test fire it is not drawing enough.  I believe that I made my burn chamber too large and so it being larger volume than my stove pipe is choking off the flow. Wondering if I can save this by going up to 8" pipe, or by adding a parallel 4" pipe to up my draw. Otherwise I will have to tear down my fire box and rebuild it with a smaller inside cross section.  I discovered late in the assembly that I was working off a design for using 8" pipe and so I narrowed it, but forgot to shorten it height wise as well. I might possibly be able to help things by adding a layer of brick to the chamber floor to reduce the inside area as well.  Anyway I am rambling ideas now and will check back fir your suggestions later. Thanks for any advice.

Ok... Time for some updates. Rebuilt the firebox after putting down 4" of cob.

Ok.  Thank you! I see what you mean.  I was thinking of the fire brick as insulation, but it is more mass... Necessary mass as it is needed to withstand the direct heat of the fire, but still needing to be insulated all around for quick heatup and better draw.
It will be a few days before I can make up some straw cob, and get that layer in. Then I will mockup again and post pics before making my firebox permanent.