Not sure that will do much.
Metal innards, no insulation, robing heat from the heat riser, that's no rocket!
An intresting idea, but completely crap in the making:
http://www.tamizsolutions.com/2012/09/10/the-rock-bucket-rocket/ http://donkey32.proboards.com/thread/1323/interesting-compact-concept
you make a proper rocket, insulated, if for heating, i would say either J tube or batch. I'm under the impression L tube is underpowered for the job. Then make a big bell around, filled by big pebbles or firebricks for example. A good trick to make the bell, instead of a barrel, is to use an old home heating fuel tank.
Here's a pic of the mass barrel/bell of Peter van den Berg 8 inch batch box at thge inovator gathering. If that can give you an idea.
https://permies.com/t/40007/rocket-stoves/Results-batch-box-thingy-Innovators
You could also do multipath rise. The exhaust of a rocket, fed at the bottom of a barrel filled with big pebbles. I insist on big, as gases have to go through. The space between the pebbles should be at least half a fist. Then you yake the exhaust, chimney from the top of that barrel. Less efficient in terms of heat conservation, but the slowing down of the exhaust path gives time to the gases to exchange their heat with the pebbles. When the fire is out completely. You can then close the J's
feed tube and the chimney to retain the heat in the pebbles and warm your space.
For everybody, i've found that a good trick, to use bare, way larger than usual "metallic chimney" inside the house, the subsequent slow down of gases gives them time to exchange heat with the high surface of the walls of that part. Like just a vertical of two barrels before the ceilling, and reducing back to 6 or 8 CSA of the system size. I think, but, am not absolutely sure, since heat rises, and the exhaust port is at the top, that implementation can't stall the system as too large a bell would. Because hot gases rise. And the chimney is still on top.
Hth.
Max.