6" BBR plunge door and cob bracing

For a while now I've been pondering a BBR for my home.
I want to build a 6" BBR with a bell, possibly as a bench.

I really like some of the features of the 7 inch batch box rocket mass heater in the woodshop at wheaton labs such as:

gravity plunge door

no metal bracing used, but cob holds the core together

I'm wondering whether the plunge door could be implemented on a "Shorty core" if the necessary air channels are built into the frame it leans against.
I like that the Shorty doesn't rely on the secondary air channel that needs replacement.

Could the "cob" bracing work on a shorty core? Or are we entering weird experimental ground here?


Thanks in advance fellow RMH enthusiasts

I'm going to give my 2 cents on this and hopefully it will revive this post and we will get some more comments.

The plunge style door should work for this as long as the air intake specifications stay the same.

As for framing, I've never done any sort of metal bracing on my stoves and just use refractory cement for the core build and wrapped in cob.

Thank you Daniel for your insight.

Sure, the necessary air channels would be built into the frame of the door. And the whole door and frame unit would be leaning against the core. I hope it will be airtight enough. I’ll see what I can come up with.

Good news that you’ve built BBRs with just cob as framing. Do you have experience with the shorty too?

And a new question: did anyone try refractory shelves (kiln shelves) for the roof of the burn chamber of the shorty? Most I’ve seen are self cast refractory.

Thanks in advance