10 gallon sized portable rocket oven

So, I have embarked on a project to make a much smaller version of the rocket stove pizza oven.  The reason I am pursuing this is that the barrel oven as designed is simply too large for the space I inhabit. This smaller oven will fit on top of my Spitfire Rocket Stove which I use for camping and off-grid cooking.  This smaller version will be portable.  

I still have to work out some details of design and it will require welding, which I have access to. It will be constructed out of a modified stainless steel liquid oxygen storage container.  The total size / volume is probably 10 gallon. There is an inner and outer container with air space existing between the two containers which should allow heat to circulate around the inner container. I have included a photo of the partially deconstructed tanks with the smaller one nested.  I have also included a sketch of two possible ways I could position the inner "oven" inside the outer container?  I am seeking opinions on the best position for the inner oven. Any thoughts on this or anything else regarding the plans as laid out?

I would favor the second iteration, for more more heat transfered to the inner oven.

I kinda doubt it will be an issue but it could lead to poor draw.
If it did, the solution is a bypass.

Hey Ian. That is a big bunch of soon to be ovens!
I second the juice box straw layout. More time for the heat to transfer to the oven.
But if it doesn’t work or the oven gets too small than I also think that with the efficiency of a rocket burn you can allow some heat to escape. At least you don’t blow up tons of smoke into your neighborhood.

William Bronson wrote:I would favor the second iteration, for more more heat transfered to the inner oven.

I kinda doubt it will be an issue but it could lead to poor draw.
If it did, the solution is a bypass.

Thanks for your input. What do you mean by bypass?

Benjamin Dinkel wrote:Hey Ian. That is a big bunch of soon to be ovens!
I second the juice box straw layout. More time for the heat to transfer to the oven.
But if it doesn’t work or the oven gets too small than I also think that with the efficiency of a rocket burn you can allow some heat to escape. At least you don’t blow up tons of smoke into your neighborhood.

LOL.  I only acquired 4 from that bunch. It will take 2 tanks to make one oven because I will need some amount of material off a second oven to fully construct the oven. I plan making the remaining two into nice large boiling pots.  I would at least hope to get something the size of a baking dish inside the oven in the oven. It will definitely make personal sized pizzas in either size iteration.

What would be the minimum sized chimney you would use?  Should it be the same size as the riser on the rocket oven?

Ian Thompson wrote:

William Bronson wrote:I would favor the second iteration, for more more heat transfered to the inner oven.

I kinda doubt it will be an issue but it could lead to poor draw.
If it did, the solution is a bypass.

Thanks for your input. What do you mean by bypass?

Hmm, hard to put into words.
The second design will stratify the exhaust gasses, so only the gasses cooled by transferring their heat to the oven will sink low enough to exit the chimney flue.
This improves the efficient use of the heat , but thwarts the fastest flow of exhaust gasses.
This can be a problem that causes smoke back  and inefficient burning when first starting the fire,but as the chimney flue heats up, it is unlikely to be a problem.

If your flue pipe had a tee opening into the space just above the inner container, exhaust gasses could flow almost  directly into the the chimney flue.
Once the glue was hot,closing a damper located in the tee would force the gasses to satisfy.
This little added complexity l would give you the best of both designs.

William Bronson wrote:

Ian Thompson wrote:

William Bronson wrote:I would favor the second iteration, for more more heat transfered to the inner oven.

I kinda doubt it will be an issue but it could lead to poor draw.
If it did, the solution is a bypass.

Thanks for your input. What do you mean by bypass?

Hmm, hard to put into words.
The second design will stratify the exhaust gasses, so only the gasses cooled by transferring their heat to the oven will sink low enough to exit the chimney flue.
This improves the efficient use of the heat , but thwarts the fastest flow of exhaust gasses.
This can be a problem that causes smoke back  and inefficient burning when first starting the fire,but as the chimney flue heats up, it is unlikely to be a problem.

If your flue pipe had a tee opening into the space just above the inner container, exhaust gasses could flow almost  directly into the the chimney flue.
Once the glue was hot,closing a damper located in the tee would force the gasses to satisfy.
This little added complexity l would give you the best of both designs.

This sounds interesting but I am having difficulty envisioning it. This would be part of the first proposed design?

I would suggest the first barrel layout, with the flue connected at the back, both bottom and top with a damper at the top connection. This gives full oven capacity and effective heating and bypass flexibility.

The flue should be the same size as the riser.

Glenn's proposal serves the same as mine but is easier to imagine and implement.