Rocket cook stove plans

[matt walker]

I've been meaning to sketch this out for a long time, and I finally sat down and did it. I want to share my idea of the best configuration for rocket stove cooking, in case anyone is curious to try it out. My drawing shows one possible type of construction. It can of course be a vertical feed, horizontal feed, bricks, a half barrel, a cast core, a fancy window cast like mine, a hole in the ground, etc.

What I think makes this so special, is that it's a fully adjustable, smokeless wood fired cooking burner. I don't think that has existed with this much control before. It's how I can smoke at a specific temp all day, or boil a pot, or sear, simmer, etc.

The barrel is also the perfect stand for whatever you want to cook on/in. Whether it's a griddle, weber, pot, wok, little stacked brick oven, or whatever.

You can route the exhaust through your chair, or just away from the cooking area, or just a little bit above you. If you want to build a half barrel bench to sit on, you can. It will warm the seat with the heat you don't use, or it can be kept simple as drawn, and the barrel will still keep you warm if you are cooking in cooler weather.

Depending on what you are cooking on, you can adjust cooking temp with a brick, or the piece of the barrel you cut out, hammered flat, or an old spatula, or whatever you can find. Use whatever it is to adjust the size of the opening on top of the barrel. In that way you can run a hot, clean fire, and still cook at lower temps.

The hardest part is cutting the holes in the barrel, and the big notch so the barrel sits on the ground over the core. I do it with a jig saw, but barrels are easy to cut with a cold chisel (or big screwdriver) and a hammer. It's loud, but surprisingly easy and accurate to cut them that way.

Anyway, this is the basic template my whole cooking system is built on, and I wanted to get it in print here in case anyone was interested in trying something similar out. Manny inspired me to learn how to draw on my Ipad so I've been sketching out these ideas in this format lately, Hope it helps to see it like this.

[DevilsBrew]

It is cool what you have going, Matt, but I would like to input my two cents since I play around with bricks so much. If you are talking about using bricks as the main body of the burn tunnel and not outer layer of a rocket, then I would say don't do it. The bricks, even with mortar and fire brick, would be a subpar material. They are fun, they retain a ton of heat, but it is a heck of a lot more difficult getting the temps up as easily and quickly as you guys do with the hard core rockets. I would recommend newbies build a true rocket with one of your cast cores and covering it in masonry. Heck, they should go for what will give them the best results.

The other piece of advice for those considering building a brick rocket, I have found that secondary air from the top at the back of the horizontal tunnel greatly improves the performance. The lower airflow of the kiln design really doesn't work with the brick rockets.

I love masonry. I don't know why. Maybe it is the earthy aspect. Anyway, this is why in my spare time I try to figure out the best way to make a brick rocket/oven combo. It may not be the best approach to cooking but I have fun with it.

[matt walker]

Yep, you can improve performance a lot with the right materials. This is just for those folks stacking bricks in the yard for temporary set ups. But ignore all that, it doesn't matter what the burn unit is made of or it's configuration, if it's burning well for you then right on. I'm saying, put a damn barrel over it already! Or not, I'm just sharing a way of cooking on a rocket stove that offers excellent control.

Another big advantage is if you cook right over the riser on a normal rocket stove, your food will have little black specks of fly ash all over it, and turn kinda grey. It's not terrible, but not that appetizing. This configuration forces the heavier exhaust to fall within the barrel and the food stays clean. If you are just boiling water or something in a pot, the approvecho designs are the pinnacle of efficient rocket cookers, but if you want some versatility, well, this is my idea of a good way to go. I'm sure there are lots of ways to skin this cat.

[rjdudley]

Matt, I'm thinking about building something to use outdoors to cook down maple syrup in the Jan/Feb timeframe. Is something like this plan workable? Has anyone tried cooking maple sap on any of the rocket stove designs?
I'd like something that can be built quickly and then taken apart and stored someplace until the next year. They only need to be operational for a few weeks a year.
Ray

[mannytheseacow]

Ray, check out my thread on Rocket Maple Cooker. It was super simple, just a horizontal feed at the bottom and a vertical shaft, all made out of 6" stove pipe and an old oil drum filled with earth/gravel/zonolite.

I was boiling down 5 gallons at a time so depending on your batch size it may or may not be viable. The down side is that I was pretty much constantly feeding it fuel the whole time.

[hpmer]

Matt's right about the fly ash. My rocket stove is used mainly for syruping in the spring, and I don't have the barrel. I get fly ash in the sap but it eventually gets filtered out as part of the finishing process.

I've been looking for a cheap barrel (read: free) for a while and will likely add one when I can.

I just finished adding one of Matt's hot plates to my rig. I added an inverted No.10 can in the back portion of the feed box. My idea is to feed hot coals under it and preheat the sap before adding it to the main pot.

I also built a wood gas stove along the line of the "Solo Stove" in case the hot plate doesn't work as expected.

[matt walker]

Ray, I'd follow Manny's advice if you are just going for maximum output. Manny, I can't remember if you had a pot skirt on that boiler or not, but again, the Aprovecho folks have pretty much perfected the rocket stove powered pot boiling rigs. Their Institutional Cooker plan is a great one for maximizing heat transfer into the pot.

This one I drew is actually not very efficient. You only end up using a small amount of it's output for most cooking tasks, unless you are trying to boil something. What's neat about it is it offers incredible control, without changing fire size. Most rocket cookers you push the sticks in a horizontal feed for more heat, and pull them out for less. This one you control like a burner on a stove. That, plus the clean cooking heat, plus the ability to use the heat you don't use for cooking to heat the humans, is why I like this design. I drew this for a friend here who loves my outdoor cooker, but it's got so much going on it was hard for him to see how simple it really is. He wants to take some parts out to the beach and throw one of these up for the weekend. I think this is a simple enough rig it can be thrown together in a few minutes once the barrel is cut out.

[matt walker]

Keep us posted on that set up Hpmer. I'm curious to see if you get adequate heat out of the plate.

[hpmer]

Will do. I imagine it should work as people cook over coals all the time in their bbq's, but we'll see. I won't know until early spring as I had to rebuild the whole stove and now I need let it dry. It's designed to be portable but was much too heavy since I had used firebricks for the burn tunnel. I ripped them out and replaced it with my clay:ash mix.

[hpmer]

Matt,

In another thread you showed your smoking setup with the adjustable baffle. I'm curious as to what your Weber Kettle mods were, i.e. how big a hole did you cut it its bottom, whether and what you may have used for a diffuser for the direct heat, etc.

And how big is the hole at the top of your barrel? The above drawing says 4" but it looked much smaller in the video.

I don't yet have a barrel but want to try modifying an old grill to fit directly on top of my heat riser and so am looking for ideas. Thanks.