Attached are pics of two smaller rocket stoves that I have gotten/made recently. The larger of the two was produced by Rocketstoves.org. The smaller one I made from an Illy coffee can, a tomato sauce can and some leftover two inch flexible steel duct that I had; I made a pot support/insulator from some 4" duct. They both work fine. The "problems" with them are that they are not very portable, even the small one; they require constant attention while being used because they EAT twigs, and they work best when there is a breeze (ironically we make windscreens to shield our petrol and kero stoves). I had both of them on this morning. It was cold - just a bit below freezing. No wind. The larger stove boiled - not a rolling boil though - a pint in 8 minutes in the pot as you see it; it never did produce a roll. It came to me without any ash insulation -too messy to ship. Once ash is added around the "burner", it will be a hotter stove. The smaller stove did the job to a rolling boil in ten. It is REAL important to match pot size to the stove; I used too small a pot for the large stove. Pete (alt+p) (alt+p)
Hi Pete, Hope you will post more as you use these units and gain valuable experience. I will build something eventually and the drawbacks and plusses are good to hear about first. Regards, Doug
It was my understanding that these were never intended to be camping stoves, but household cooking stoves in severely impoverished fourth and fifth world areas where wood is the main source of cooking fuel and is getting scarce or lethally dangerous to gather. Where the people in these festering cesspits are to obtain tin cans, ducting, expanded steel mesh and the tools to work these materials when they have neither a steady supply of water nor anything to cook in it is another question. Gerry
HI Pete, nice to see others here with an interest in wood stoves for camping. The points you brought up with regard to the Rocket stove are the very same that I eventually gave up on that design. Yes they are cheap and easy to build but so are wood gasifying stoves and are much easier to work with. I'll explain what I have discovered. Rockets have to contiually be nurtured, ya gotta keep feeding them or they cool and will start to smoke again when you finally get back to them to feed a little more wood because the gasification process gets interupted. An inverted down draft style gasifying stove is lit from the top and burns down. It does not smoke at all like the Rocket style except in the first 30 seconds or so of lighting until gas production is underway. The stove burns waaay cleaner and is so easy to control heat output, all you have to do is incorporate an airgate into your design. My wood campstove looks similar to ones on the net but I have made improvements that have really enhanced it's performance such as...........2 liters of ice cold water in minus 5 celcius outside temps to a FULL rolling boil in just over 12 minutes. (no lie!). The stove only measures 3.5 inches wide and 4.5 inches tall - very packable. Put your firestarting material inside the fire pot when packing and you have a very compact stove......not to mention you never have to worry about running out of fuel or the expense of buying it either. As you mentioned the Rocket likes the wind. The gasifyers dont mind it but like a gas or kerosene stove, the more sheltered the stove is from the wind the more heat is transfered to the pot and a quicker boil results. I use a tinfoil windscreen that will completely encircle the stove and the pot up to approximately 3/4 of the pot wall height. It truely is strange to see continuous flames that are 8 inches or so off the top of the stove and there is no accompanying smoke (barely perceptable) and using wood pellets for fuel I can get a 2 hr and 15 minute burn time and there are still plenty of red hot coals at the bottom of the can to warm your hands over fro another half hour or so. All that on a soup can full of pellets! Using twigs (preferred fuel) the heat output is the same but does not last nearly as long. Using twigs the loading of the stove is very influential on stove performance but I have never had it take longer than 15 minutes to bring 2 liters to a full rolling boil using the windscreen. Mostly what I use the wood stove for is heating water. Thats 90% of what all fuel consumed in camp goes for anyway. I will use a gas or parafin stove for simmering jobs like rice or frying a steak etc. But that will change too I suspect as I continually improve the primary air intake controls. The reason I like twigs it they don't burn as long. Most cooking sessions are less than 1/2 hour in sesssion. When I load the stove with twigs, that boiling water will be held at a full rolling boil up to the 40 minute mark at which time the stove changes over to charcoal burning mode and will continue to keep a pot hot but not boiling for another half hour. If there is interest I can post a few pics showing it in action. Ian....
Ditto that "I'd like to see plans". That stove sounds like something special. I made a wood gas stove last summer - very simple and effective. I'd like to make more. The rocket types are easy to make but have the downsides as I mentioned - and they turn pots black with soot. One of the upsides to Rockets is that they can be made from other materials. In the third world, where metal is scarce, they can be made of clay or bricks or stones and mud or.... Pete
Hi Guys, to my knowledge there is not a wood stove out there that will not blacken your pots. Believe it or not that is actually a good thing! Because blackened pots heat faster1 So you get yourself a little ditty bag for your pot. When you pack up to move on the pot goes into the bag, gets pulled up tight with draw cords and is kept isolated from the rest of your gear and will not get everything around it dirty that way. As for plans.......sorry the best I can do is provide a few pics. These are pictures of the stove that does the full rolling boil in over 12 minutes and still under 13 minutes. The drawback to this prototype that I have found is the inability to control the primary air flow so when the stove and fuel get all cranked up, there is no way to throttle it down! So at times like in the photo where there are flames coming up and around the pot the stove is producing more heat than can be utilized as shown. What I did tho was to utilize a tin foil windscreen wrapped tight around the pot up to about the 2/3 to 3/4 of the way up the pot point. The screen is fashioned around the stove at the bottom being left slightly open. Because all air for the burn of the stove enters from the bottom (both primary and secondary air supplies) it does not matter if the foil is tight to the pot. I will seem like there is no where for the stove to draft very well but it still manages to and there is very little heat lost to the surrounding air. These shots were taken during the very first test burn and all I had to use for a windscreen was the aluminum standing behind the stove. The pot was pre-blackened from many camping trips prior. Notice the ice and snow still on the surface of the deck. Some will tell you a gasifying wood stove will not work well below 40 degrees F. but the secret I have found that really helps out is to have double wall construction with in the stove that draws secondary air up from the bottom and through between these two walls so the fire is heating up the air between the two walls as it burns and and then the secondary air enters at the top of the fire to provide heated air necesary to complete a very clean burn. The pot in the photo is the same one I got the 12+ minute rolling boil from. Notice the kleenex between the stove and the cake pan? I put that there to determine whether or not the stove could be opperated on surfaces like a picnic table without charring the surface it was on. (Leave no trace camping) This shot is about 5-10 minutes after lighting. This shot is roughly 20 minutes from lighting. And finally this shot is after the stove has reached full gas production. See how much heat would be lost if the tinfoil screen I described was not used? This is not the smaller dimentioned stove I mentioned of 3.5 x 4 inches.......those dimentions are for a smaller more recently built stove that performs equally well with better burn times. I am just realizing that when I was telling you about the stove that I was actually descibing aspects of two different stoves that I have built. The dimentions of this stove are 5 x 6.5 inches. I built the smaller one so It would fit inside my two liter pot! Ooops, just realized I screwed up a bit. Reverse those two top photos. The top one is actually the 20 minute one and the second is the 10 minute one. Here you see the stove once it has made its transition from gasification to charcoal burn. And here, although there is still plenty of heat coming off of it there is not enough heat to use for anything other than keeping something warm.....like your hands. Note that the stove burns so completely that all that is left when done is a tiny bit of white ash.....sometimes not even that.. Also in this last shot you can see the secondary air supply holes at the top of the inside can. The air comes in the outside can at the bottom and the inner can is held off the bottom of the outer can by three bolts with nuts that go though the inside cans bottom to provide a tripod affect and to keep the fires heat off the bottom of the outside can. Incoming air also cools the bottoms of both cans somewhat. Questions? Fire away! Ian....
Great pictures Ian, to be honest, my favorite stove is an open fire Even a small contained fire will throw out the heat way more than a stove 8)
Hey Richard, well I really enjoy an open fire too. Where these stoves excell is in the fact that there is no smoke and will only consume 10 percent of the fuel of an open fire to do the same job. The reason for this is the fact that the woodgas is being burnt as well as the wood and those gasses are what are normally given off in the form of smoke. I dont think you could ever get a 12 minute boil off of an open fire because you have no way of focusing the heat. I hope you are not confusing a gasifying wood stove made from tin cans with a standard tin can wood stove. The theory behind their opperation is entirely different.
Ian: Is the smaller stove just a scaled down version of the one in the pics? Are there any holes in the inner can other than the ones toward the top? I assume that the bottom of the inner can is perforated. Same basic question again about the outer can - any holes other than the ones at the bottom. The reason that I ask is that my first (and only) wood gas stove, a single wall version (Mark Jurey design,) had many holes drilled in the flat bottom, in addition to holes in the sides and top. How did you make the flange for the inner can? I found this article about a single walled wood gas stove a while ago but have not tried ithis design: http://www.garlington.biz/Ray/WoodGasStove/. Pete
Ian: Is the smaller stove just a scaled down version of the one in the pics? No, the smaller stove has an airgate for the primary air which enters from the can bottom and not the side like in this stove. Are there any holes in the inner can other than the ones toward the top? Yes, the bottom of the inner can has an 1/8 inch hole every 1/4 inch in all directions. I assume that the bottom of the inner can is perforated. Same basic question again about the outer can - any holes other than the ones at the bottom. Not in the outter can. How did you make the flange for the inner can? I simply took the can's cut out after removing it from the end of the can and cut out the middle section so as it would fit around the top of the inner can. I just used tin snips to cut out the ring/flange. I found this article about a single walled wood gas stove a while ago but have not tried ithis design: The Garlington stove works fine as does the Mark Jurey Penny wood stove that you mentioned. In fact the Mark Jurey stove was the very first of many I have made. But the double walled stoves work much better. and burn cleaner because of their ability to preheat the secondary air supply and also sometimes the primary air supply as well.
OK I'm interested, and having built large wood burning stoves, understand the secondary burn concept very well. I heated my old house with a small wood burner I built, and it was the one design we did that had secondary combustion constantly. So I have come up with a design, and am about ? done with it now. I have a couple of options I?m going to be able to play with, and will have something to post in a day or three, (We have family coming over tomorrow. So I may have a 1 day hit) Basically I?ve come up with a triple wall design that should deliver hot air to the primary combustion, and super hot air to the secondary, and have an air flow restrictor that should allow the burn to be adjusted a bit. The design is a bit complex compared to the ones that have been mentioned (Googling Wood gas stove got a lot of good hits?), But well within the average hobbyist capabilities, the most difficult part being some cutting with aviation snips. Working on the pot holder part of the design just now?
LOL, no I'm not, my main hobby is bushcraft style camping and your type of stove is popular with some of the lads, in fact, I must get/make one myself
Thanks all, for the great info being added to this thread. It is very interesting to me. I'm trying to work out a fastpack kit that uses an old short tank version of Primus 71. The bare stove shows up every so often and I have scarfed 3 of them. For reference, a Primus 71 short tank weighs about the same as an Opti Nova (without the pump assembly) I plan to use a snowpeak 600 ml pot (which I often use with pepsi and penny stoves). I use a tripod made with aluminum tubes and titanium tig rod of .062 or .094 inch diameter at the top of the legs to tie them together and support cookware. Coathanger wire works too. I plan to use .007 inch thick titanium windscreen (bought on ebay), Snowpeak 600 ml mug, and a tripod, or two rods across the top for pot support, or cutouts in the top of the windscreen for exhaust gas passage if using a larger pan. A 4.75 inch diameter x 5 inch tall windscreen would weigh about 40 grams. Lots of experiments still to be done. The object was to also be able to convert the windscreen to a wood burner. I would not use the stove or the tripod in that case. I would use machined titanium buttons with a smaller OD shoulder machined under the button, and a machined nib with a small hole in it on the back of the button/shoulder to use to rivet the button (the same way a shoe eyelet is rolled) onto the wrapper with the buttons facing the outside. Then all that is needed is 2 or 3 of the buttons at the seam and matching keyholes to put the buttons in to lock the wrapper into a tube. The wind screeen would fit inside the mug with the stove. The stove, Snowpeak 600 ml mug and Ti sheet in .007 thk. packed stove and potlifter concept drawing, double wall not yet considered obviously Regards, Doug
http://www.woodgas.com/Woodgas stove.pdf In this article is a simple easy to construct air gatel They all pretty much work the same way. Just build what you need for your designl Very simple stuff. Has to be or I would be hooped hehehe. Ian...
Hi Ian, That's a very good link. Thanks for putting it on & I will have to try some can units to that design type first to get some valuable experience. Looks like great fun. Regards, Doug
Ian, For an air flow control,...........what if you raised the burner can inside the outer wall, put in a secondary floor (about an inch below the burner can's grated bottom), and used a deadbolt-like slide mechanism to operate a flow. In other words, the secondary floor would be the intermediary vent between the outer wall's holes at the bottom of the side and the grate itself. For the vent, putting two good sized holes in the intermediate floor and using that simple slide vent would be easy and could be supported in two places(on both sides) instead of a single mid rivet from woodgas.com's idea. Pull the vent one way and it's open fully, slide it back in it's closed and unobtrusive. The intermediate floor could be rigidly put in place with J.B. Weld, or similar, fairly easily and allow for a tight vent. The only problem I could forsee are the possibility of ashes clogging things. To eliminate this a removable burner can (from the top) should solve any issue. Just pop it out and give it a shake between burns. the slide vent/deadbolt lock would hold it all tight when inserted again. Sure it's more work,.........just a thought.
Priest, you could probable do all of that and it would work really well but why bother? Thats a lot of extra work to accomplish a very simple thing. I simply used the air gate in the link that I provided and utilized two revolving cans, one inside the other. Rotate one way to open up the gate, rotate the other to close down the gate. Simple, yet works beautifully. With that said, go ahead and build one like you described Priest. That is half the fun right! and there is always a sence of accomplishment when it pans out the way you planned. I look forward to hearing how it turned out. Ian....
Doug, yes there is a lot of information on that site. But I must forwarn you I have not had any luck what so ever with trying to utilize that gas wick set up. I have yet to get a good enough draft to pull the flames up around the wick and out the top of the stove. It always just started smoking. I tried lots of different things but nothing worked very well. If you have any luck please let me know what you did. Thanks Ian....
