Newb with some questions; Round or Square burn chamber?

Hello All,

I have been experimenting with some ideas but I am pretty new to this wonderfulness y'all call RMH. I'm looking into making my own Dragon Heater inspired bell for my house and I'm wondering if anyone knows what the folks at dragon heaters used to cast their refractory and what the stack boards are made of. Also, any ideas on where to get some rough dimensions for a 4 inch system? I have plans from the ultimate survival bundle for 6 and 8 inch and I just want to make sure I can simply scale everything down or if it is more a matter or ratios rather than strict measurements.

I also have been reading way too many of these forums and my head is spinning from info overload. So, does anyone have a straight answer as to which is better, a round or square burn chamber. If it is a function of friction on the walls and cross sectional area then wouldn't a hexagon be excellent? Just thinking because it occurs so often in nature where perfect circles and squares do not. I have the ability to make a hexagonal burn chamber and was thinking about putting a twist into it to a get a little rotation going in the burn chamber. Just for fun.

Thanks!
Tobias

Hi Tobias,

I'm also new here, so I can''t tell you which is better, but that question has come up in my mind as well... I'm thinking the round one, cause it doesn't have any corners. Wonder what the experts will say.

Corners make for more turbulent air flow, which is what you are aiming for in a rocket burn chamber. Round cross-sections are for minimizing turbulence and having laminar flow, which is what you want when pumping liquids.