Rocket Stove Prototype

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I have been doing research on rocket stoves for some time now. I would surely not make it like this again as it was WAY too labor intensive, but would build future stoves out of rectangular and round tubing. I cobbled this up from a piece of scrap 12 gauge hot roll a couple of months ago before I made my welding table mainly to give my plasma cutter and welder some run time. I plan to add a flange on top to make it a modular design which can accept accessories such as cooking grate for skillet, box-in-box oven, instant hot water plate heater.. you know.. for when the lights go out. It's not a portable design, more a base camp stove, but I plan on doing some different designs as well. It creates a virtually smokeless HOT fire within 1 minute from sticks laying around the yard.Attachment 871281Attachment 871291Attachment 871301Attachment 871311Attachment 871321
Reply:As stated.. Just a prototype to test the design and burn characteristics.Attachment 871331Attachment 871341Attachment 871351
Reply:Very cool. What is the little chamber where the sticks go for? Air flow?
Reply:We played with 'em in the shop, whipped up a few. They were basically twins to your design except we used 4x4 tube. I cooked a few meals on 'em, myself.I agree, their performance is amazing. If I hadn't seen it I wouldn't believe it. I had seen some videos, but I was still a bit of a skeptic.Yes, a HOT roaring high BTU  fire in no time, fueled by practically nothing; sticks and scraps. Crazy.The problem is they need to be fed a steady diet of that nothing. So it takes a standing fireman to keep one stoked. Okay I suppose if you're there anyway to watch your steak cook; or if option B is to freeze to death. But otherwise a pain.We played a bit with larger charges and more "preloaded" fuel, but any changes from the basic design seemed to kill performance. I'm not sure what became of the projects or interest. I guess spring arrived and young men's fancies turned away from rocket stoves. HahaGood LuckLast edited by denrep; 10-13-2014 at 11:17 AM.
Reply:That is great.  Looks like an easy way to get rid of sticks in the yard.  Do you have some dimensions you could share?
Reply:Ok What is it really used for ,heat,cooking,? I don't see any cooking surface. doesn't look like it would work in an inclosed space  so heating is out , And if I was out side  I would rather have a fire with logs  than spend the night searching for kindling. I have seen the little jet stoves at MEC and they are built for one fitted kettle.(   http://www.mec.ca/product/5031-449/biolite-campstove/ )
Reply:double post sorryLast edited by gxbxc; 10-13-2014 at 01:13 PM.
Reply:Originally Posted by gxbxcOk What is it really used for ,heat,cooking,? I don't see any cooking surface. doesn't look like it would work in an inclosed space  so heating is out , And if I was out side  I would rather have a fire with logs  than spend the night searching for kindling....
Reply:Would a chamber above the flue trap the heat, and make it workable, or would the mass of trapped hot air in the chamber kill the updraft?Mighta answered my own question"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Samm, you should toss one together sometime, just for grins. It only takes a couple minutes to whip up  the basic feeder and stack.It's really dumbfounding the "roar" and heat out of practically nothing for fuel.We used re-bar for legs and as support for iron pan cooktop.
Reply:To answer a few questions in a couple of paragraphs rather than a bunch of quotes:mnt: yep, the place where the sticks goes does provide "some" of the draft. The space below the where the sticks are fed provides more draft.gxbxc: wood availiabilty both large an small is not an issue here. Small split wood burns hotter and longer than twigs, so that works too assuming that it will fit into the mouth of the stove.Some stuff on rocket stoves and this style in general:The rocket stove is actually an idea conceived for the 3rd world country environment. Their traditional way of cooking is the 3 rock method in which three large rocks are places on the ground to create a triangular pattern. Burn chamber in the middle with space between the rocks to feed fuel. The 3 rock method has been linked to respiratory disease among indigenous folk as they run them in their huts/houses/shanty's. The women of the villages would spend a lot of their days in a smokey environment tending to the cooking of the house. To add to that, the three rock method while effective, also has a low fuel to heat efficiency rate. The rocket stove was designed around this issue. It creates both a smokeless fire and requires a lot less wood as the fuel to heat efficiency rate is MUCH higher allowing them to only use what is needed to cook the meal at hand. This also means less time looking for wood. Their designs are actually much different looking as they incorporate stock pot cookers, stove tops, dual pot stoves etc. The dimensions can vary widely but there is a semi-official area/airflow/draft formula to use that will allow you to make proper considerations when designing a stove. I can go pull a couple of measurements off of mine next time I am out there.This rocket stove is just one of MANY possible designs. The thought process was that it is just a heat source to power accessory attachments. I have four pieces of angle that I need to weld to the top of the stack which will act as a flange for connecting accessories. The accessories will have an identical flange on the bottom that will mate with the flange on the stack.- For instance, a cooking grate capable of holding a 24" cast iron skillet with a flange attached at the bottom could bolt to the stack flange.- Another example is a box-in-box oven attachment. A box in box oven would have an inside box capable of holding a casserole pan or two which would be mounted inside of a second larger box allowing for a couple of inches of air space between them. Frame the inner and outer box where they nest with strip steel and you have a sealed exhaust path. Add an insulated door with a high temp seal to complete the cooking space. A short stack would be mounted to top and bottom to allow gasses to flow around the inner box, but within the outer box. A flange on the bottom stack would allow it to be bolted to the top of the stoves stack.- Yet another is an instant hot water heater. Modular flange as usual to attach to the top of the stack. You can use a coil or plate design, but the idea is to have one side connected to a hose or gravity feed water supply. As the water passes through, around or across the rocket stoves stack, it comes out steaming hot on the other end.- There are other ideas such as steam generators that can be created that could potentially power a generator, but that is a whole separate venture in and of itself.Rocket stoves by design do require an operator to tend to it more as compared to burning wood in a fire pit, wood stove etc. However, hardwood burns a lot hotter and longer than sticks and twigs and that can extend the burn time depending on thickness/hardness of the wood. I have a fire pit out back that can burn any of the wood that the rocket stove cant handle and that's  fine for leisurely cooking during good times, property clearing, debris burning, marshmallow cooking, etc. but it takes longer to get a solid bed of coals, smokes a lot more and requires a lot more fuel. The rocket stove starts a strong draft within 20 seconds (bacon grease paper towels as starter) and is emitting a clean flame from the top within a minute. Walk 50 feet away and you don't smell it burning as you would a campfire or firepit; this to me is a great stealth feature.This style rocket stove doesn't have a lot of surface area to generate radiant heat, rather a majority of the heat is expelled out of the stack making it specifically a concentrated heat source. Other designs exist that allow you to suspend the gasses in a secondary burn chamber that work really well for heating shops, garages, etc. For example, if you were to take this stove and build it within a 100lb propane tank (narrow and tall), with the stack releasing its flame/gasses within the tank. At the lower part of the tank a second separate exhaust stack would come off which will go through your roof, out a wall, etc. This will allow the primary burn chamber exhaust it's gasses into the propane tank, create a back pressure where they will be suspended and re-burned and eventually leave the second exhaust stack and out of the shop. The increased surface area and gas suspension allows it to burn even cleaner (if designed properly) and will emit some serious heat from the propane tank surface where the gasses are suspended. The next level up from there is rocket mass heaters where hippies around the world heat their houses with.Additionally this particular design is of course not portable via backpack, etc as it is heavy more suitable as a base-camp stove. It is hard to compare this type of rocket stove with a biolite, as they both serve different purposes. While this stove may heat a gallon of water faster than a biolite (some what speculative as I have not actually used a biolite) it is not portable and cannot do the job of the biolite if you need to travel by foot. A stove similar to the biolite which I think is pretty neat design is the solostove (minus the built in cell phone charger, but hey thats what solar is for) http://www.solostove.com/ These little stoves such as the solostove or biolite is really getting into the top lit up draft (TLUD) category and is another cool design in itself which is a great lead-in to gasifier design. In the gasifier realm, there are folks creating clean blue flame generation from scrubbed unburned gasses utilizing minimal wood fuel. There is even a FEMA writeup out there that details the gasifier design. Pretty neat stuff.As far as usefulness goes, I remember our last prolonged power outage. On DAY 1 the Wawa parking lot where I used to live was FILLED with people standing around and sitting on the curb eating breakfast sandwiches, etc. I thought to myself, REALLY?? 1 day and you don't know what to do? They had made no preperations for the event.. Thanks for the compliments.-NicheLast edited by NicheFab; 10-14-2014 at 01:48 AM.
Reply:Pretty cool! Makes me think of my Kelly Kettle stove. Works on the same concept.
Reply:Originally Posted by farmersammWould a chamber above the flue trap the heat, and make it workable, or would the mass of trapped hot air in the chamber kill the updraft?Mighta answered my own question
Reply:Originally Posted by manningA google search for "thermal mass rocket stove" will show what I mean.
Reply:A fellow nearby built that sort of furnace in a hole in his cellar floor 8 feet deep. When finished he had only a hatch for starting the fire, a stack for smoke, a 4" for air, and an angled 12"? well casing sticking out at an angle passing through the wall to outdoors. Once the fire box was full, he could fill the long 12" pipe, it would burn down enough to allow another chunk of wood to fall into the fire box. He had no duct system, and allowed the heat to be stored in the earth.
Reply:I guess that would work if there was no ground water.
Reply:Wow, you certainly built that one the old fashioned way cutting every piece from flat stock.  Really cool idea and it looks like it works great.  I might have to build one of those for my back porch.