Baghdad Ion Stove

[SGT Rock]

Baghdad Stove Update

My last stove update from Baghdad was about an extra small cat stove I was playing with. After a lot of playing and tweaking I decided it was not a good design as it was finicky to set up and run. Trying to simplify the stove only caused more problems to the point it created a fire hazard trying to pack such a powerful design as the Cat Stove into something as small as I was trying to make it. I did however end up with a cool interim design – basically what I mentioned in that last update. I never perfected a simmer with that small of a stove; any effort to choke it from air somehow resulted in a fireball where the stove ran away and was engulfed in flames. But I did play with stove design however making some variations of my small Ion stove.

See, before I deployed, I was playing around with the Ion stove trying to make a stove that was as fuel efficient as possible. The goal was to make a stove design that could be consistently made and would consistently perform. In the past, I had made the tiny Ion stove, but could not get consistent performance from it, nor could the stove be easily reproduced where the copies work as well as the original. Some others took what I had played with and posted, and then ran with the ball.

Some important lessons learned from the Ion were:

A smaller diameter for the burner focused the flames to the center of the pot and allowed the flames to work to the outside of the bottom as they burned rather than starting near the sides and burning up along the side of the pot, wasting heat.

Minimizing fuel capacity to the absolute minimum possible also reduced stove size, reducing weight. This also allows for smaller pot stands and small windscreens, which also reduce weight.

Add these to the strategies I have already established such as using fiberglass insulation to increase the efficiency by decreasing priming time and the proper way to make a windscreen for the best performance, and I had a good foundation to work with.

The goal has been to heat one pint of water to a roiling boil. What I have also found is that some pots are more efficient than others. My SnowPeak pot is one of the best since it uses a curved bottom to maximize contact area with the flame. I have not been able to achieve the same fuel efficiency with flat bottom pots, but since these are the normal pots for most hikers, getting the Ion stove to work just as efficiently with this style has been a key goal.

So over here I have gotten the bug again as I was playing with the new Brasslight Turbo I and II systems (good stoves I plan to review later), my pitiful attempt at a smaller Cat Stove, and my evaluation of the Anti-Gravity Mamma’s Kitchen. After some tinkering and observing, I think I have finally achieved my goal, but only returning home and performing measured testing will finally prove if I’m reaching boil. Here is how I did it:

Taking the Ion idea of making the fuel container short, I cut small juice cans to the absolute lowest it could go and still hold about ¾ ounces of alcohol – about ½” tall. The double wall design was prone to fuel leaks even after sealing it in lots of places, and the aluminum cans were prone to split during construction, and that resulted in a lot of wasted effort and unusable scrap aluminum. The burn characteristics were also not as good, it tended to result in overuse of fuel as the small cans heated up rapidly and had little space for the fuel go, ending up in a larger than needed flame pattern, actually as big as the flame pattern from a full sized soda can stove.

Then I thought about moving the burner holes to the inside lip and focusing them to the center of the burner. To do this it required me to leave some inside material to place the holes. Since the small cans have so little material to work with, I ended up with a design that would not allow me to cut the entire center out of the bottom. This change also kept me from making an inner wall which in the end was a positive change since it made construction easier. The new, shorter design would have ended up with fuel coming over the top of the filer hole, so I increased the height back up to ¾” The stove worked better, but once I added the windscreen, the heat feedback resulted in a near runaway stove with huge flames shooting up past the sides of the pot and wasting fuel again.

So the problem at that point was how to focus the flames better and reduce the preheated air getting at the flames. I decided to try making a ¼” tall collar of aluminum to focus the flame a little more, the results were pretty darn good, so time for the next model to reduce the parts.

This time I made the burner just like I had been doing, but made the fuel reservoir 1” tall. Then the burner was pushed down into the reservoir (this was actually the easiest stove of them all to make) and making the pot stand 1 ½” tall. To help make the pot more stable than the original Ion stove and also protect the lip that focus the flame, I made a pot stand from ½” hardware cloth (again, thanks to Rosaleen for providing just enough material) which was snug around the stove so it formed a single unit.

The stove worked better after a few burns (probably getting the fiberglass singed just right) to where I could consistently raise 1 pint of water from approximately 60 degrees F to a rolling boil (visual verification only) with only 12ml of denatured alcohol. Something else I was able to re-produce consistently was the ability to simmer with the stove by using only 6ml of fuel. The stove will burn at a low heat for 9.5 minutes with only 6ml fuel without adding any extra parts. And all this was achieved using a flat bottom aluminum non-stick 1.5L pot with lid.

To verify the fact that this design could be reproduced consistently with similar performance, I took two total novices from my unit one night and guided them as they each made their own stoves using standard tools. Both of them produced replicas that performed just as efficiently on their first try, even though they didn’t make them nearly as pretty as mine.

So now I assume based on my observations that this stove is doing exactly what I want it to. Of course getting home in a few months and verifying it is necessary, I figured I could put it up at my site if I could get a good connection, and let some of you stove tinkerers play with it and see what you think. Maybe you can find something to tweak it or see a flaw in the design somewhere, but that would be a good thing.

By the way, as I modify and play with stove designs, any resemblance between this stove or any ideas presented here to anything else that has been designed somewhere else is purely coincidental and just means that someone else out there is smarter than me and thought of it first.

If the picture is too small, just enlarge it. The images are sharp enough to still be seen if you blow it up.

[CanoeBlue]

VERY neat Rock! It certainly looks like a new concept to me - and thanks for sharing that with us. I will build one today.

One question - how do you convert between flat-out heat and simmer on this stove without any additional parts?

Thanks for the update.

[SGT Rock]

Well first thing I should mention is a design point I forgot. When you finish setting the two cans together, push your thum down through the hole until you make a slight bowl shaped depression directly under the filler hole, this keeps a little fuel exactly under the hole for priming when you fill the stove through the hole.

If you want to simmer (and I rarely reccomend it, pot cozies are more fuel efficent), let the fuel run out frmo the boil, then take the pot off the stove and let it sid for about a minute or two off to the side, it will not get cold or loose much heat in that short of a time. In about a minute or two the stove will be cool to the touch. Add 1 cap full from a soda bottle (about 6ml) and then re-light the stove and put the pot back on. For some reason, the stove never gets hot, it will make a very cool looking small halo of blue flame that will last about 9 1/2 minutes and keep the pot and water above 190 degrees F for the entire time.

I suppose if you wanted to make a cap, you could take the bottom off of another can and cut it to cover the top of the burner while leaving one small hole, then you could try that so you could add it to the stove after achiving boil. But the stove is so small, that you can't put a lot of fuel in there to begin with anyway.

[slabfoot]

i like it Rock but it begs to be tinkered with. after I get your results I think i'll invert the burner and press it in, and then maybe an inner wall that just fits inside the burner/filler hole. this will allow infinate variations of burner height and inner wall height to optimize flame characteristics and burn times....I should be able to keep busy all winter.
thanks Rock and merry Christmas,

bill

[SGT Rock]

I did some tweaking. First I cut a ring to make an inner wall from the side of a can and put some notches on the bottom for fuel, then simply put it into place constricted and let it expand into place. That doesn't seem to change much.

I raised the pot just a hair and trimmed about 1/16" of an inch off the lip left on the fuel resivoir. The key is to get the flames where they just start to turn yellow as they touch the pot. Works a little better when I did that.

[Hog On Ice]

thanks for getting me to try something new SGT Rock. I now know how to put a perfect .75 inch hole in the top of a can (I happened to have a 3/4 inch chassis punch left over from long ago when I tinkered with tube based radios) This works great for the hole in the can. Anyways I went and put together one of your new designs and tried it - it worked OK but in my case with the pot I use it wasn't significantly better than the original Ion stove I was using. The pot support however turned out to be better for the pot I was using.

Now as you are aware optimizing a stove design depends on many factors and a stove that is optimized for one pot may not be optimal for another pot etc. In my case these days I use a chopped off 24 ounce Heineken beer can as my pot. I only boil water in the can and then pour the water into a ziplock bag in a cozy to do the actual cooking. Anyways the 24 ounce beer cans have a fairly small bottom and I think that this is where the difference in our results comes from.

Well anyways since I had got the fiberglass in the form of a strip suitable for wrapping around a pipe I decided to go ahead with a very simple design - the thin aluminum bottom from a tea candle filled with two layers of the fiberglass pipe insulation (comes right to the top of the container) and used this in place of the Ion stove but with the new pot stand. This simple stove worked very well for me and IMO was noticably more efficient for my setup than either Ion stove as well as being lighter. Another advantage of this simple design was that the stove was very easy to light with a Spark-lite flint sparker saving the weight and bother of a lighter or matches.

Well anyways - just some more experiences from the home built stove front.

[kank]

Very interesting stuff, SGT Rock. Glad you've been able to do some tinkering out there. I am curious about this new stove design. I haven't got any cans on hand to try it with, but will try to pick some up soon. I am wondering why the little stoves are so much mroe efficient than the larger ones. Is this because they take longer to boil (less heat output escapes because less is being generated)? Your new stove has obviously done away with the complexity of a double-wall stove. In doing so, you have almost pared the design down to what they call an Altoids stove (http://www.backpacking.net/makegear/altoids-stove/), where they punch holes in the top of an Altoids tin and fill it with perlite. This is a low-pressure design where the fiberglass/perlite wick is keeping evaporation rates high enough to sustain the stove's output.

My question is this: at this point, is your burner top still serving a substantial purpose? I realize that the fiberglass and inverted bowl shape of the reservoir probably keeps most of the fuel vapor flowing from the burner holes, but the design on the whole is basically a cup of alcohol with a wick and no longer depends on the inner chamber for pressurization. In fact, you have noted little difference when adding an inner wall to the Baghdad Ion. You have tinkered with these stoves enough to understand them quite well and I just wanted to hear anyone's thoughts on this. I notice that HOI has taken the concept all the way to a simple tea candle tin filled with fiberglass. Since the system is the thing that really matters and not just stove design, are we headed to a point where all of our tests involving hole count and diameter, stove height versus pot height, etc all boil down to an individual system and not the type of burner design at all? Aren't all of our stoves basically just cups of alcohol that burn at a certain rate? That burn rate would depend on a balance between the heat generated and the heat absorbed by fuel vaporization. When we burn various types of stoves, we are only really affecting that balance of heat output, right? If the Baghdad Ion can be more efficient than any Cat (has that air preheating and mixing design) or double-walled stove (mixes with O2 entering around the base of the jet like any gas burner), then it would seem that it doesn't matter one bit whether our design tries to provide ample mixing with oxygen, etc. It would seem that the Baghdad Ion has no way for air to reach the fuel until the fuel vapor spills outside the perimeter of the stove cylinder (perimeter wall should help prevent air from reaching burner jets themselves). I want to build one of these stoves to witness the flame for myself, but it would appear that the stove jets have little access to oxygen inside the stove cylinder and therefore the fuel could be burning at the edges of the cylinder, as if the pot support itself was the burner surface. However, the picture posted by SGT Rock, which shows the stove burning, implies otherwise, since it would appear that the flames are mostly contained within the stove cylinder. Is there some obvious point that I am missing? In a double-wall stove, the burner style allowed me to easily imagine that the alcohol vapor was mixing with the surrounding, incoming oxygen just like it does on a gas cookstove. Now that the Baghdad Ion has "buried" the burner jet in the interior of the cylinder, how does this air mixing still occur in an efficient manner? Our discussions of isopropyl alcohol implied that it need high amounts of excess oxygen to burn without too much soot and waste. My own background with fossil fuel heating systems tells me that the amount of excess air does indeed matter in those reactions. Do the "lesser" alcohols burn efficiently no matter how well they mix with surrounding air or is there something about an alcohol oxidation reaction that makes it almost "foolproof": delivering its BTU output regardless of burner design? Admittetdly, there's never visible smoke or soot from ethyl or methyl flames, so perhaps it just burns a certain way so long as oxygen is available somewhere.

As usual SGT Rock, you've given us an interesting stove design. Your pursuit of fuel efficiency over boil time has always held my interest as the fuel efficiency is my own main concern when using these low-BTU alcohol fuels. I think it was a great idea to have the novices in your unit build their own models of this stove and test the reproducibility of your performance. Having never been able to match the efficiency of some of your stoves (probably due to my pot's flat bottom and any number of other factors), this makes me very interested in building a Baghdad Ion to test in my own system. One of the fellowship (all the folks involved in the alcohol stove threads on Around the Campfire) needs to test this design with an accurate thermometer to help nail down the performance numbers. If I can get a couple of cans to do so, I will definitely try to do some tests. Some of the folks that have contributed to the great research and ideas in this forum have probably not yet realized that there is recent activity here or they would already be testing this.

Thanks SGT Rock and best of luck in Baghdad! I hope the days pass like hours until you get to come home!

[SGT Rock]

Very interesting stuff, SGT Rock. Glad you've been able to do some tinkering out there. I am curious about this new stove design. I haven't got any cans on hand to try it with, but will try to pick some up soon. I am wondering why the little stoves are so much mroe efficient than the larger ones. Is this because they take longer to boil (less heat output escapes because less is being generated)? Your new stove has obviously done away with the complexity of a double-wall stove. In doing so, you have almost pared the design down to what they call an Altoids stove, where they punch holes in the top of an Altoids tin and fill it with perlite. This is a low-pressure design where the fiberglass/perlite wick is keeping evaporation rates high enough to sustain the stove's output.

I haven't actaully seen this stove but, I have heard of it. I'll look into that.

My question is this: at this point, is your burner top still serving a substantial purpose? I realize that the fiberglass and inverted bowl shape of the reservoir probably keeps most of the fuel vapor flowing from the burner holes, but the design on the whole is basically a cup of alcohol with a wick and no longer depends on the inner chamber for pressurization. In fact, you have noted little difference when adding an inner wall to the Baghdad Ion. You have tinkered with these stoves enough to understand them quite well and I just wanted to hear anyone's thoughts on this.

Only in the sense that it limits too much fuel from being ignited at one time. Now that I am figuring that out more and more, there may be a better way to make this part work. If I did add more holes, then the height may have to change, same with less. I think the area or amount of fuel that can ignight at one time will influence the pot heigt, I also assume that allowing too much fuel to ignight at one time may cause a run away stove where the pot height may not completly control the flame.


I notice that HOI has taken the concept all the way to a simple tea candle tin filled with fiberglass. Since the system is the thing that really matters and not just stove design, are we headed to a point where all of our tests involving hole count and diameter, stove height versus pot height, etc all boil down to an individual system and not the type of burner design at all?

Could be that HOI is smarter than me :D, I know he is wiser already.

This hits on something I have been thinking about lately as well. I think that the next step for me to try is the smallest possible burner I can make that will still hold about .75 ounces of fuel with the smallest possible burner diameter. If I could achive this with a tealight candle thingy, then that may be the answer. Then it would simply be an issue of adjusting the pot height and such. The funny thing is that I was thinking about the exact same thing about two days ago as I looked at a tealight stove that Rosaleen sent me a few months back "Can it be done?" Apparently the answer is yes - except maybe the fuel volume in that particular burner. I will play with it and see. The reason I say .75 ounces is I feel that some room for colder temperatures where the water may need more fuel to achive boil should be provided.

Anyway, if I can get a container that will only hold .75 ounces and has a small burner pattern, then I may only need to add some sort of air limiting system similar to the simple little lip I left on the juice can to adjust the fuel/air mixture.

If the Baghdad Ion can be more efficient than any Cat (has that air preheating and mixing design) or double-walled stove (mixes with O2 entering around the base of the jet like any gas burner), then it would seem that it doesn't matter one bit whether our design tries to provide ample mixing with oxygen, etc. It would seem that the Baghdad Ion has no way for air to reach the fuel until the fuel vapor spills outside the perimeter of the stove cylinder (perimeter wall should help prevent air from reaching burner jets themselves).

Before I make the claim more efficent, I would justify that with what my idea of efficency is - fuel efficiency. If a hiker's idea of efficency is heating water fast then the Cat will win. But it is a minor point. But I have never been a proponent of pressurized designs - I find them to fincky to make and don't see a need for all that. If the stove could be made by just using the bottom of a tuna can and some bailing wire, then that is the best way to go :cool:

So anyway Kank, I will try to dig out that tealight stove and play with it. I will post the results of that here and prove HOI to be lightyears ahread of me LOL.

Take care all.

[SGT Rock]

Well I didn't have a lot of luck with the tealight candle at all. The design was basically a double wall tealight stove that Rosaleen sent me. I found that it used fuel up too fast no matter how low I put the pot, although I eventually got so low the stove would go out when I put the pot on it. I tried a couple of tricks like making a collar to change the air flow, but it reached what I called the "Atomic Fireball" stage when it got hot. Flames would shoot in unneeded directions, wasting fuel and heat. I think I will have to build one from scratch if I want to make it work.

[steve hiker]

Sgt. Rock you may want to look into patenting or otherwise protecting your property rights in these stoves (if you haven't already done so). An hour's consultation with an intellectual property lawyer would be a good investment, in my opinion. Talk to the JAG office and they can probably refer you to someone in that field.

Looks like you have something really good going that could bring in some side money in the future, if you wanna go commercial. Even if you have no interest in making money, it'd be a shame to see some big mfg rip off your design without you getting the credit. Just my .02

[blackdog]

Another option would be to "opensource" it under the apropriate license.

more info on that at:
http://creativecommons.org/learn/licenses/

a nice comic-style info at:
http://creativecommons.org/learn/licenses/comics1

With the amount of work you've put it, sir, you deserve the credits and cash.

[SGT Rock]

If I do anything, it would likely be some sort of open source since I have borrowed on so many other people's designsfor getting ideas whether or not I am still using them. I really don't mind the sharing of ideas. I guess if I wanted to open a buisness making stoves it would be a totally different thing alltogether.

I will look into it though.

[steve hiker]

SGT Rock --

While OpenSource looks interesting, it appears to be applicable to written material (copyright) not manufactured goods (patents). Also, if you have copied others' work in making your stoves, you may have exposure for patent infringement yourself.

Also, even though you're not interested in making money, patenting your design may be wise b/c:

(a) An established mfg could "dumb down" your stove and sell an inferior product to the public at large, most of whom aren't familiar with your stoves. Wouldn't you want the backpacking public to have the real thing, the best design?

(b) As mentioned above, you still may have exposure for patent infringement for the work you're doing now, although I'm not sure how the law would apply if you're just giving the design away.

(c) Honestly, don't you want the credit for what you do?

In any case, I suggest talking to a lawyer rather than relying on general information on the internet. Ask for referral to an attorney in the field of intellectual property.

[kank]

While I hope that SGT Rock does come up with some worthwhile stove design that deserves patent protection, I think he's right to say that many of these alcohol stoves designs and ideas are basically public domain at this point. If he comes up with a "special" trick or something that a patent office might find noticeably different from other designs, then he should protect the idea. Otherwise, we are basically working with a "community of ideas" that have been mixed and matched from person to person, each contributing a little something here and there. The pepsi can stove itself undoubtedly stems from some single person that realized that using the end recesses of a soda can would allow for a double-wall, self-pressurizing alcohol stove, but I'm not even sure who actually invented the thing. I'm pretty sure it was around before all the internet hoopla got started, but perhaps someone else knows more about the origins. Scott Henderson posted the first instructions that I found to build a double-wall soda can stove over at PCTHiker.com, but he doesn't seem to take credit for inventing the idea.

At any rate, SGT Rock has spent enough time testing, designing, and building alcohol stoves that he deserves any credit that comes his way, but I doubt that there is anything in his designs that a patent office would find noteworthy. I hope he comes up with something great, though! If he did get a stove idea patented, I'd probably buy a stove from him :). I think SGT Rock has put a lot of time and energy into all manner of hiking gear and methods on his website, especially alcohol stoves, and many of us appreciate the opinions and information he has provided. I find that in many of the discussions I have on various outdoors-related bulletin boards, I end up posting a link to some page at SGT Rock's site. That is a pretty good compliment to the contribution he has provided to the "online" backpacking community.

Still haven't tried to build this Baghdad Ion stove :(. Been very busy and that might not change for a couple of weeks.

[SGT Rock]

Kank,

Itake that as a compliment. It sort of re-enforces why I started this site. Back in the day before I had it, I would try to post something I used or did and it was often difficult to do in a forum. So I started the site on a free server to have a place to add a link to whatever I posted about a lot. I have noticed (when I was home) that some of my top refering links were now other people linking to my site to show something I had put up on it.

As to the stove. I now have one that is even smaller and just as efficent. It uses a couple of small juice cans and is only about 1/2" tall. I think I have hit on a way to do this with a tealight candle thing when I get a couple. The one I buit is working OK after I did some improvised sealing using aluminum foil, the probelm I'm findin though is to get the optimal pot height for my tealight stove I have to put the stove fairly close to the pot. This causes a problem with flame and heat feading back at the stove causing it to buen too quickly. I don't know if I can overcome this. I figure my new stove is at about 0.4 ounces with windscreen and everything, and the tealight could be even lower if I could get it to work right.

I'm running out of alcohol.

[blackdog]

If the big center hole of the BIS would be replaced by six smaller holes halfway out from the center, would the "pit" between them hold enough alcohol for priming?

[SGT Rock]

In my original experiments it didn't.Plusthe main chamber was very hard to fill without having a center hole, those burner holes were too small to fill it in an efficient manner.

[peter_pan]

Rock,

You gotta try Atlanta Randy's Atlanta Stove.....IT IS AWESOME...mine weighs 10 grams total....brings 16 oz of water in a old BSA mess kit pot, 0.8 qt capacity, to a rolling boil in 3 minutes and burns a total of 4-4+ minutes on 0.5 oz consistently....lighter than any thing posted that I've seen and faster, with no moving parts...$0.25 for a potted meat can. $.17 for a brick angle alum flashing sheet at Lowes...Or use the alum foil top out of the new plastic canister coffee cans instead of throwing it away( Free)...Tools: a push pin from bulletin board, household scissors, and plyers or a good grip (hell a spring clip closes pin will work). 5 minutes to make....no moving parts....this stove really does rock.

[SGT Rock]

I did make one almost exactly like that, I lost too much heat up the sides of the pot.

[blackdog]

I meant replacing the center hole (not the burner holes) with a ring of holes a bit like a kitchen drain, but saving a small cupped area at the very center. The ring of six roughly 3mm holes should allow for easy filling while automagically keeping a tiny amount of alcohol at the center. The center cavity could be made deeper with a metal ball, the back of a screwdriver handle or similar.

[SGT Rock]

Well I did try a stove made like that, it didn't prime well, sometimes taking a couple of tries to get it going.

[Rosaleen]

Hey, Sarge!

Too bad I didn't check out this thread sooner.

I keep tinkering, too. I have had plenty of success with using the tea candle stove with my beer can and sausage can pots. The key seemed to be using less fuel per fill. I may have used 2-3 teaspoons. When a cook kit is 4 to 6 oz (depends on size of pot and fod jar), including matches and towel, I don't complain about refilling the stove! :biggrin:

An interesting discovery was an open candle cup actually seemed to work nearly as well as the double wall candle cup stove so painstakingly constructed for simple water boiling. Sheesh!

Happy Trails!

Rosaleen