Rocket cookstove design with reused cooktop

Hi guys!
I'm in the process to design and make a rocket cookstove to put in our natural outside kitcken we are building here.
Next to a rocket oven (about which I have another topic going on 'search for rocket oven designs'), I want to build a normal cooktop as well, and with rocket science integrated, I hope it will be quicker and more efficient then these old style wooden cookstoves.

The aim for the kitchen is that it will be the center point in the community. Used by people living here and by visitors who stay on our small natural camping.

As I'm planning two wood fired 'installations', I hope to catch the leftover heat from the chimneys with a thermosyphon system. Heating up water through copper pipes around the chimneys, that feed a boiler hanging under the roof of the kitchen. Ideally this water could be used for dishes and in some outside showers, still to make . Any tips or advice for systems like this? Ofcourse pressure valves

I've been researching a bit on different models and types of rocket stoves to cook on. Although most I found had also the purpose to heat or at least add to hiuse heating. The one i'm building will be in a half open outside kitchen, so I hope to focus the heat as much as possible on the cooking surface.
I stumbled on some videos from a guy who made a very small, efficient rocket cookstove, that looks very promising. It's basically an L tube flipped down, or J tube with flat riser. The top of the 'riser' is actually the cooking surface, so where the heat gets hottest it gives the heat off to the cooking surface.
These are the videos i'm talking about. Very interesting bunch of videos actually. https://youtu.be/VFAwl6aJNH4
So, with this design, I went on to experiment. I had an old wooden stovetop still laying around and imagined that would be a good size for the cookstove I want to make in this kitchen. Clearly a lot bigger then the one in the video, but I can also get quite a bit bigger in general with the system.
I got some firebricks and went on to make a quick experimental set up. First time i just put one layer of the bricks (7cm) and a bit of clay to close the gaps with the stovetop. Made a little firebox and added a diy chimney.
With this version, I couldn't get the flame and gases through the system.
Too small get it pulling good.
Next day I remade it 2 bricks high, so 14cm and a bigger firebox. This went a lot better already, once the chimney started pulling it went really good and got to +-300°c on the first place to cook. Then I modified some parts, added a ramp to push the heat up and added my secondary air channel from my BBR inside in there. Then it went really well. I got to +- 330°c on the first pit and 250°c on the second.
The downfalls still present are the time to heat it up, and a little struggle to get the pull going in the beginning. Ofcourse this experiment is without any insulation. The final design I'd like to insulate very well to it focused all its heat to the cooktop and heats up quicker, also a real, long chimney (that's insulated?) Will be better for a good draft I guess?

Do you guys have any suggestions on how to improve this design? How to focus most efficiently the heat to the cooktop? How to insulate it properly and what materials to use for it?
Many thanks for your suggestions!!

I'm adding some pictures with description to this so you'll know what i'm talking about more

Grtss an excited rocket experimenteer

I am not sure how the stove works or why it is called a rocket stove but in the video it looks like his tiny stove requires a very tall chimney, so you could try that to start.
Most rocket stoves require exacting dimension and specifications that produce a very hot and fast burn that in turn burns off any smoke.
So far all the designs I have seen need around 1000f + to function properly.
Interesting design though…..
A well built J tube can make a fantastic hot plate cook stove, the concept is very well tested and very basic in construction.

Thanks for the reply!
Well... Clearly the stove uses 'rocket science'.. the secondary burn of the gases here just happens under the cooktop itself.
Without any insulation at the moment, when it's all insulated I think it'll get a lot more efficient.
And that's what I'm wondering about, how to get to insulating this one properly, so it gets 'max efficiency'

Yeah, a long chimney will improve pulling for sure.. right now, I just have this, but when i make the final design in the kitchen i'll put a long chimney through the roof.

I know about fixed/tested rocket designs and have made a BBR before. Doesn't mean you're not allowed to experiment with what you have, right?

You mentioned well tested J tube cookstoves. Haven't found clear topics or models on this though... That don't focus on heating the house as well.
Have you got any good recommendations or links?
Thanks 👍

Yes sure have a look on my channel I have several working hot plates that use proven designs.
There is a 6” J tube with a huge hot plate and a 4” vortex that works a bit to well but I an still perfecting that one….

Yep, nice!
Saw your topic and videos about the 4 inch vortex rocket. Cool man!
Kind off doubting to change mine into a vortex or DSR...

I don't seem to find any drawings (sketchup) from the vortex types. All files on donkey proboards i found aren't reachable anymore, and it seems like quite a tricky built..

Well the vortex stove needs to be built to spec and it is not the easiest stove to get running perfectly from the start as there are so many variables  but a well built J tube will run faultlessly.
The drawing are quite  accessible  on proboards but it is a long thread now….