Pönttöuuni Finnish heater (Russian Rocket)

Saw this on YouTube:  

Firstly, I thought it was interesting that he seemed to get some rockety, type behavior during his "efficient" burn. Second, I thought that someone might find his design sketches useful for rmh variations. Third, he has an interesting challenge of wanting to test an old original design against the "simplified" mass produced ones and I thought someone might want to play with that.

Also, looks a lot like a Cottage Rocket. 😁