Pat, the four experts - the genuine, experienced, time-served article, that is - whom I named in my post above in this thread offer a wealth of nitty-gritty information, which will take any student of (real) rocket stoves a good while to digest. I endorse them highly. They know their stuff, having spent years actually installing rocket systems for clients, and are up there with Larry Winiarski and Ianto Evans, the original pioneers of the basic idea of rocket stoves for poor peasants in fuel-poor situations.
On YT, you can find a vid of Erika and Ernie sitting in their cottage in the Okanagan Highlands in Oregon explaining the performance of their rocket there, which heats the whole house.
Strikingly, if you’re feeling supply pressure, Erika says at one point that since they installed the rocket they’ve gone from using - from memory - four cords of wood per heating season to about half a cord!
That sort of simply astonishing fuel economy is often remarked by people who are using genuine rockets, built according to the basic physical principles which Larry worked out at Aprovecho research labs something like forty years ago now.
Another mine of information - including CD sets giving extensive information on the matter - is Paul Wheaton at Permies.com.
Peter van den Berg has a dedicated YT channel with masses of material. He too is wholly on top of the theory, and has lately created another big leap forward in rocket stoves with his batch-box burners, and his development of the ‘port’ structure between the primary and secondary burn compartments of his rockets. Peter’s constant testing, and his grasp of combustion physics, makes him a worthy successor of Larry, who died recently. He knows his stuff in depth. He also has his own website, which bulges with high-grade nitty-gritty inf on making rockets.
Rockets are easy to build, if you’re a mucky-handed practical person, with some basic workshop facilities. Note in particular that when they’re running properly - because they’re built according to sound principles - the temperature in the secondary part of the flue-path can reach 1200 C or more (sic!), which means that the secondary part of the path should be exclusively built of high-temperature refractory material, which also needs to be a light-weight insulative material too. Insulation is a critical key to - proper - rockets, which is why so many of the cargo-cult pretend rockets on YT never reach the full, high-efficiency working temperatures, which literally burn up all the fuel-gases and burnable particulates - aka smoke - that are normally lost to the atmosphere in less efficient wood stoves. This also makes them unusually clean-burning, of course, since ALL the fuel is burnt before the flue gases exit the exhaust stack.
One consequence of this is that you can’t use steel for the interior lining material in the flue-path, at least not in the secondary-burn part of the path, because it will spall quickly under the extreme heat stresses, and will even in some cases actually melt! It’s this basic fact which will allow you to sort the YT vids into those where the posters actually know their stuff, and those who are just know-nothing band-waggon-jumping cargo-cultist. Uninsulated, all-steel ‘rockets’ are a joke! Don’t get drawn in.
If you’re considering a dual-purpose rocket, for both cooking and home-heating, you’ll need an RMH - a rocket mass-heater system. The standard form that began it all is the the Ianto Evans style heat-store cob/masonry bench set beside the stove itself, and through which the hot gases are lead.
If you’re ever near the truly extraordinary Cae Mabon village, on the opposite shore of LLyn Padarn across from LLanberis in Gwynedd, Cymru Gogledd, you can see one of Ianto’s early RMHs in the cob cottage that he built their for the guy who created Cae Mabon, and who still runs it: my old buddy Eric Maddern. I’ve lit that particular RMH several times, and I can testify what an astonishing job it does at heating the cottage on next-to-no fuel…
But note that lately, an alternative form which has some extra advantages is the heat-store masonry ‘bell’ - which see. Several vids speak of them. Paul W has some enlightening vids about that.
Just these few leads will keep serious seekers of practical knowledge about - real - rockets busy for quite a while. Lots to digest, lots to tinker with in your workshop…
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