In-ground pocket rocket?

Something I thought of earlier today, and I'd like to run a couple of ideas by the folks who have done this stuff more.

My thought, since steel 5-7 gallon cans aren't as common here as they used to be, was to basically come up with a top plate with feed and flue, then use a 5 gallon bucket, or a similar sized piece of culvert pipe which would also double as a liner, to size a hole in the ground to put the top plate over. The area I'm dealing with has red clay just under the surface, and bedrock not far under that, so it might have to be adjusted if the bedrock is less than a bucket length deep. That got me to wondering how important the internal volume, diameter, and shape of the hole are to a pocket rocket design, as culvert pipe comes in lots of sizes, and can be shaped with some effort for an oval chamber. Rather, I guess the question is which of those are most important and how would they be figured, or do I just need to weld up a plate and start digging different holes?

Obviously, this dumps a lot of heat into the dirt, which could possibly be used for pit baking in parallel holes nearby, or the hole could be filled in after a long burn and the warm ground then would be a sleeping spot. The top plate should be usable as a "stove top" for cooking as long as there's enough flat space left after the feed tube and flue are in place. (Where an oval chamber becomes handy to give more plate space.) The flue would be the source of "people heat," which leads to the question of how much turbulence a pocket rocket this size could take in the flue. Thinking in terms of a 4" flue with an 8" section about two feet long at or 6-12" above the "lid" with internal baffles to hopefully radiate more heat off the pipe there while maintaining at least a 4" equivalent path. Ideally, flue total height would still be around 6-7' above the plate so it could project above the roof of a small lean-to or similar shelter.

Sort of like a Dakota firepit?

Joe B : I can predict the final results! !!! As soon as the moisture is baked out of the soil The now highly insulative earth will rapidly raise the internal temperature

up into the range where the pocket rocket could be used as a simple forge ! Followed very quickly by the total failure of the 5 gallon pail culvert section or even

1/8th inch plate steel ! Though the last one might last several days ! For t5he good of the crafts ! Big AL !

Miles Flansburg wrote:Sort of like a Dakota firepit?

Not so much, in that what I'm planning would be essentially a Pocket Rocket, but using the hole in the ground as the bucket, and a separate metal plate flush with the ground as the lid. Feed and flue tubing attached to the plate would be the only parts above ground. Not sure how the insulating (compared to a steel bucket) effect of the ground would change the behavior of the Pocket Rocket, though.

allen lumley wrote:Joe B : I can predict the final results! !!! As soon as the moisture is baked out of the soil The now highly insulative earth will rapidly raise the internal temperature up into the range where the pocket rocket could be used as a simple forge!

That could be really handy in a survival or just long campout situation. The family land occasionally turns up old bits of plows and other implements, and my "base camp" spot is near the dry wash that was used as the family dump for about 80 years. It's all been covered over, but every now and then erosion will uncover a bicycle frame, washing machine chunks, etc.

Followed very quickly by the total failure of the 5 gallon pail culvert section or even 1/8th inch plate steel ! Though the last one might last several days ! For t5he good of the crafts ! Big AL !

I was thinking 1/4" or maybe even 1/2" because scraps seem to turn up from time to time in sizes that would work. Frankly, if it's hot enough to kill culvert pipe, it should also sinter the sand and clay, making the liner unnecessary.

One other thought; wouldn't cast iron fare better as a lid than mild steel? One of the finds from several years back that's still mostly buried out there was part of a cast iron stove that had been broken up, but IIRC, a good bit of the top was still intact and might be usable for that.

Hi Joe,

What ever comes of this...I do hope...successes or failures...that everyone comes back and shares the results...

If the plan is "just experimenting" go for whatever is dreamed up and try it...

If seeking advice...listen to that which given...Metal does not last very long at all, and if that is acceptable then charge on with the plans. If a long term build is the goal, then make up some schematics for folks to look at and critique. This should render a build with much more life and durability.

Earth does not "sinter" as described and what little are does become unbalanced with the surrounding area of earth and exfoliates.

Hope that is of some help... Do let us know what is discovered...

j

Jay C. White Cloud wrote:If seeking advice...listen to that which given...Metal does not last very long at all, and if that is acceptable then charge on with the plans. If a long term build is the goal, then make up some schematics for folks to look at and critique. This should render a build with much more life and durability.

For the most part, it would probably be a temporary/intermittent use backup solution anyway; ultimately, I'd like to build an outdoor RMH out there as pretty much the cornerstone of a base camp. (What would you use for the outer shell of the mass and the fire area when it will be exposed to north central Texas weather? Heavy snow is rare, but thunderstorms, hail and long intense hot droughts are an annual thing. Temps range from -5 to 115. My thought was the readily available onsite limestone flats and blocks with OPC mortar on outside of the mass, but not sure what to use where it gets really hot.) It's a pretty spot, among mesquites just about military crest on the leeward side of a ridge that runs perpendicular to the prevailing west wind with pecans and other food sources within 500 yards, and an open field where deer and rabbits are common just at the downhill edge of the trees, so permanently setting some heavy duty stakes for a lean-to or wall tent over the thermal mass, a small Rocket Stove at the fairly sheltered spot where I wash up when I camp there, and other low-impact permanent "improvements" are on the long-term plan. Just too darn cold (for a Texan anyway) and gets dark too early right now to go play with the ideas. (Bonus is that it's 10 minutes from work and 14 from home, so it's perfect for a "screw it, I want to camp/fish/hunt/shoot/stargaze/pit-roast/just-plain-be-inaccessible-to-everybody-except-the-close-friends-and-family-who-know-where-it-is tonight" moment.)

Earth does not "sinter" as described and what little are does become unbalanced with the surrounding area of earth and exfoliates.

Just drying that clay moves it from the "hard to dig" category into "drive in a drill rod and blast" territory, so I'll need to plan the initial dig for March or April anyway. Once it dries a liner may be completely redundant. The hand-dug well nearby had a more-or-less uncased (limestone basically mashed into the damp clay and then mortared with an inch or two of unreinforced cement) section that held up for at least 80 years before it collapsed, so it's pretty stable stuff.

For the most part, it would probably be a temporary/intermittent use backup solution anyway...

For this one...experiment with whatever thought there may be...test things out and learn from what works and doesn't...We can all gain from this when shared...

...ultimately, I'd like to build an outdoor RMH out there as pretty much the cornerstone of a base camp...

This needs tried and true modalities...

...What would you use for the outer shell of the mass and the fire area when it will be exposed to north central Texas weather?

Even for central Texas, or up here in Vermont, when an outside bread oven and/or heating bench is built in the natural methods...it tends to be built traditionally with a cobb mix and perhaps a cladding of tile or stone...some are more stone than Cobb, as we have access to soapstone sources thought this has become less common except for higher end builds into oven and other masonry heater types...Most often under a heavily overhung roofed pavillion structure to protect it from direct weather degradation...

One of the biggest battles I seem to be constantly engaged in is with OPC and all those out there..."trying"...to use it. In modern construction (and that is subjective) it has applications...in natural building...very little, to none at all. I see video after video...funny part is, no one makes videos after any time has passed to show the results. OPC stucco and add mixes do not work with cobb. Some 5% and 10% portland additives to RE structural walls have some merit, yet simple hot lime or hydraulic lime mixes do much better. So if really necessary for a design to work, you can clad the cobb in a lime render.

I really like the idea of limestone flat stones. Incorporating them into the design is a good idea. I have even seen some really nice timber frame pavilions built with stone roofs, and I have rebuilt a number of diver stone/slate roofs over the decades...they are enchanting and ever enduring. Build a structure like this and your great, great, great grandchildren will enjoy it. Even fossorial architecture (what folks today are calling "earth ships") would do much better if they built in traditional styles like this instead of trying to rely on all the modern plastics and rubbers alone...

A friend...Dan Snow...has built several and this is probably some of the finest examples below...

Once it dries a liner may be completely redundant.

Well...not neccsarrly. Yes cobb can be formed into all manner of shape and some will hold up to higher temps but cobb alone will exfoliate if left to the temps of parts of the burn chamber of a RMH. Yes, you can make bread ovens with it...and these should not be subjected to temps above 1000 °F as the interiors will exfoliate even in really well built ones in a short time. The burn chambers of a RMH go well above this.

The hand-dug well nearby had a more-or-less uncased (limestone basically mashed into the damp clay and then mortared with an inch or two of unreinforced cement) section that held up for at least 80 years before it collapsed, so it's pretty stable stuff.

Perhaps, but not a permaculture material (the OPC that is) per se, nor able to withstand the temperature of a pottery kiln which is what parts of a RMH have to endure.

Try reading some of the key referenced material spoke of all over Permies.com and you will have a good foundation for a build. I, and others, will always be here to go over details.

Good Luck,

j

Joe B. : What Jay said, I to would like to see how this works for you, I think your best shot is a soil with a high percentage of clay/ hardpan !

I am in the process of making up a set of links to the heart of the matter 'High Temperature Hydrogen Attack !' Hydrogen and Steam Embrittlement.

Until this is finished you will have to Google the terms, This is a start of My 1st attempt ! Big AL


https://permies.com/t/41287/rocket-stoves/High-Temperature-Hydrogen-Attack

allen lumley wrote:Joe B. : What Jay said, I to would like to see how this works for you, I think your best shot is a soil with a high percentage of clay/ hardpan !

If I can run down a piece of plate and a couple pipes of the right size for feed and flue, I'll tack together the "lid," and next time I have a reason to be out there for a few hours I'll dig a hole and see what the dirt does with that much fire in it with no liner. If nothing else, it sounds like a fun experiment.

Joe, if you could, put someplace that you can just keep it going whenever you get a chance. Run the thing hard, and see what fails (or doesn't.) We would love photos of you progress and findings...and thanks for sharing it all within us...

Good Luck,

j

Jay C. White Cloud wrote:

Really wish I had the talent and the straight tree trunks to build something like that. Even though I'm technically in the "Cross Timbers" area, I'm well over to the deciduous side of it, so we don't get many of the nice straight, tall conifers around here. That would be perfect for a base camp with a RMH mass running along the back wall and a RS just out front to cook on when it doesn't need heat inside.

Hi Joe,

I have done one like this in Southern Arizona years ago in Mesquite wood, and we work in Texas (or our crews do) all the time. Let me know where you are and I might be able to put you in touch with a local "free lance" sawyer that can get you stock...it doesn't have to be straight at all. Most of the wood in the photo came from a "firewood" pile and is made up of oak and ash...

I would love seeing you build something like this! If you have the "stones" to build and experiment with a RMH...you can build what is in that photo...Just take your time and ask questions if you need help...We're here for that reason...

j

Jay C. White Cloud wrote:I have done one like this in Southern Arizona years ago in Mesquite wood, and we work in Texas (or our crews do) all the time. Let me know where you are and I might be able to put you in touch with a local "free lance" sawyer that can get you stock...it doesn't have to be straight at all. Most of the wood in the photo came from a "firewood" pile and is made up of oak and ash...

I'm in Stephenville and the family land is about 5 miles due south of town. We have lots of mesquite in every size up to 16", but of course, most of it is so twisted as to make any project a constant process of re-planning based on the actual shape available. As for rock, the cap of the ridge is limestone that has partially exfoliated about 200 yards from my preferred spot, so there's a lot of flat and block there, plus a few piles scattered around that 130 acre area where fields were cleared early last century, and four cousins own most of the remainder of the 600+ acres of the original farm with even more piles where other fields were cleared.

Great granddad had several outbuildings built during the Depression (he was a farmer and nurseryman - usually couldn't afford much labor but the situation provided a surplus of people happy to work for all-your-family-can-eat food, a dry place to sleep and a chance to earn a lease of an acre or two to build a cabin on) from limestone and sandstone blocks, and all of the smaller ones are still solid and in use today, with a couple of them still being lived in.

Clairette is about 6-7 miles farther south, and the ruins there are a pretty good example of what a man who's good with a chisel could do with local rock, though most of great granddad's buildings were built with unshaped blocks in more of a trial-and-error method of stacking them until they fit right, then mortaring them in place. http://www.texasescapes.com/CentralTexasTownsNorth/ClairetteTexas.htm

Can anyone explain what this is?

One of the biggest battles I seem to be constantly engaged in is with OPC

I think it means Ordinary Portland Cement.

Hi John and William,

That was my best guess, but I’m not sure.