Stove performance?

[SGT Rock]

For ya'll that make your own stoves, how do you measure performance?

The reason I ask is because when I first started, I prefered the Cat Stove because it is an inferno. It makes hot water like a volcano. My primary concern was seeing hot water made quickly, and the Cat Stove is about the best for that. You can see bubbles forming in this sucker in about 3:30 or so depending on weather. But when I started truely testing stoves I found this was only about 175-200 degrees. IT takes about 24ml of fuel to get a true 212.5 degree boil in a Cat Stove.

After I started testing fuel efficiency of stoves, I've been working to maximum efficiency for that because in the end, this means I carry less actual weight. My current stove only weighs 0.3 ounces and has a 0.3 ounce windscreen for a 0.6 ounce total. But best of all, it can achive a true 212.5 degree boil with a mere 12ml of alcohol, but it takes about 11:30 to get there - but I don't mind the weight. And I've even figured out how to make this stove simmer (if I want it too) for 21 MINUTES on 6ml of fuel without any extra parts! But if it sounds too good to be true, it may be - this is only in kitchen conditions, I still need to trail test it before I post the instructions.

I've found a good middle ground of solid performing stoves, the Turbo V8 stove being my current favorite.

But It gets me to the tortise and hair thought. A stove that heats water quickly is like a dragster, it takes a lot of energy to do it. While a weight efficient stove is like a Honda Hybrid car, it is slow and small, but highly energy efficient. Some hikers like the sexy volcano like stove (I know I did), but the slow burning economy stoves are probably the best for us.

So anyway, back to the original question, how do you measure your stove performance?

[Hammock Hanger]

I'm real precise... Does it cook my dinner! Actually most soda can stoves I made were unreliable as they would cook fast one day and not at all the next. That's when I went to the tangia. I never really got down to measuring the time, the amount of fuel, fuel used per minute, etc. I carried one bottle of fuel - it lasted 6-7 days. My water boiled up in a couple of minutes, I was happy.

Sgt Rock: You are one man for DETAILS! I think that's a compliment.;)

Hammock Hanger

[highway]

Originally posted by SGT Rock

IT takes about 24ml of fuel...
....it can achive a true 212.5 degree boil with a mere 12ml of alcohol..
21 MINUTES on 6ml of fuel without...

So anyway, back to the original question, how do you measure your stove performance?

I don't mean to offend but,speaking for myself, I'd prefer the measurements not in the metric system, but in our antequated, archaic, English system. Those little mililiters are a little difficult for this 'ole Southern boy to get a quick grasp on. I'm not bad on Km for distance but the metric volumetric measurements seem to slip on by me. Now, if you would just convert them to ounces[weight], a unit which most of us use daily, it would make it easier for us to grasp the significance of your findings. I honestly don't believe many US citizens can quickly picture a ml, because we just don't use them much, yet.......and I'm not even sure I want to!

[SGT Rock]

Sorry about that Highway.

Up until very recently I was using measurements in 1/4 ounce increments, based on the belief that a cap from a soda bottle was 1/4 ounce. But it turned out I was a little off. Turned out that a soda bottle cap is approximately 6 ml of fuel. So when I say it takes me 6 ml, it really means it takes me one cap full of alcohol from my soda bottle. When I say it takes me 12 ml to boild, this means it only takes two caps full. I used this as a standard because it is easy to measure in the field.

Now to convert it to weight, well that is a little more math. Alcohol weighs .82 ounces per fluid ounce, so a 12 ounce bottle of fuel weighs 0.9 ounces (for the bottle) and 9.85 ounces for the fuel, or 10.75 ounces total. A 12 ounce bottle of fuel is really 355 ml, so that is almost 60 caps filled. That means with my stove I can boil 30 meals, or boil and simmer 20 meals. Honestly a 12 ounce bottle will last me about 1.5 to 2 weeks of hiking.

[Kerosene]

Here's a good on-line calculator that will help you convert those ml to ounces, and much more!

http://www.onlineconversion.com/

[highway]

Kerosene:
Here is the best one I have found:

http://www.convertit.com/Go/ConvertIt/Measurement/Converter.ASP

But, the problem I see is converting a measure of volume(mililiters) to a measure of weight(ounces avoirdupois or weight ounces) as opposed to volumetric ounces(fluid ounces). The problem in these tests is they are mixed and confusing. On the one hand the weights for the stove are, by necessity, given in weight ounces, which we can all understand. But the alcohol consumption is given in ml, which is difficult to grasp and not readible convertible. I have done some trangia tests and weighed the alcohol consumed on a balance to get weight ounces, as opposed to measuring the volume(metric[ml] or English [fl oz])because what is important is the weight carried for the alcohol to be consumed, not the volume carried for the same alcohol. So, since the weight of the consumed alcohol is appropriate, I have attempted to convert and am having difficulty!

A mind is a terrible thing to waste.

[SGT Rock]

Well in my case, I measure the amount I burn by volume, so I track it that way. I don't try to determine weight until I know how much I need for the trip, then I just multiply by .82 and have my answer.

If I were to calculate it by weight, then I need about .32 ounces to boil and about .16 ounces to simmer. I'm still testing the stove to make sure there are no flukes in the results. So far I've only tried the 6ml test (.16 ounce) once but was amazed by the results. I could really care less if it simmers though, I'm only interested in boiling.

Anyway, my goal this entire process is to equal or beat the Trangia which I've found the be the best stove for fuel econemy, but not weight economy since the base weight is so high. If I can get it to the point it boils as well and consistantly as the Trangia with a low base weight, I'll be happy.

If you really want to get math intensive I can give you a bunch of figures to show why I should be able to boil a pint on 9ml of fuel. :D

[highway]

I swear I hate mathematics. I have always been challenged in that arena. But I do struggle and try, though, to decipher everyone I find. I need to ponder it some more; its most likely not as significant as, at first glance, appears.

But damn, a stove weighing 0.30 oz. What did you make it out of, fairy wings?

[SGT Rock]

Actually it's made from a couple of grape juice cans. Here is a URL, but the data is way from complete. It's currently more an article on what I'm doing and experimenting with. Some of the numbers are WAY out there because I'm still tweaking the design. The final tests and article are likely to look different.

http://hikinghq.net/sgt_stove/ion_stove.html

Promise not to take it all as total fact yet. I've also got some pictures comming.

[EarlyRiser]

ah high school chemistry, conversions between english and metric how i loathe thee. i grew up learning metric because thats what they are trying to teach in schools now so i guess i have a bit easyer time grasping it. but i mean we all know how big a liter is because its about the volume of a nalgene a mililiter is one onehundredth of a liter. a liter is a decimeter cubed and a mililiter is a centimeter cubed. think of it as a box which each side of the box being divided into one hundred sections (ten along each side) the large box is a liter the smaller are each a mililiter. and then to convert to weight youd have to find out the weight per liter of whatever substance you are using in the case of alcohol i believe it was said that it was .82 ounces per fluid ounce and theres all the conversions and everything so yes it does get confusing and if this helps anyone than awesome i really did learn somthing in chemistry.

[slabfoot]

Sgt. Rock

Saw your post and ran rite out to the garage and made one. of course I did not follow your instructions exactly, so it cooks like a blowtorch but won't do the simmer gig. Difference was I packed in the insulation fairly dense and made 32 holes high on the burner rim with the tip of an exackto blade. boils very nicely though but I have probly lost a lot of efficiency.

[SGT Rock]

The burner holes are the big difference in your stove and mine. If you get a chance to try making it with the loose fiberglass and low hole numbers the performance will supprise you, although be prepared to wait about 13 minutes or so to achive boil. Mine is the exact oposite of a blow torch, and that is exactly what I'm looking for.

[slabfoot]

I just finished a new micro wid only 8 holes and loose pack on the fiberglass. took 3 capfuls to acheive boil about 9 minutes and still does not simmer. I think the problem is that i'm using a Kevin S. windscreen/potstand cut for good boil time on my shrunkened pepsi stove. It sets the pot above v8 micro to 1 inch. of clearance. Ican only do so much here at my desk, but I am going to try it at 3/4 and 1/2 inch clearances to see if I can't get the efficiency and the simmer effect. I am driving the guys here at work crazy since I keep borrowing time in the welding booth to do my tests.

[EarlyRiser]

just like the ion engine nasa uses. it only produces about as much thrust as the weight of a piece of paper on your hand but it can accelerate to tremendous speeds efficiently. slow but steady wins the race right? i dont mind waiting a few minutes for my water anyway, i can sit back and relax or even do a few things around camp.

[SGT Rock]

Exactly Early Riser. The whole aim in lightweight hiking is efficiency of weight.

I figured using methyl alcohol, you would only need 9 ml (theoreticly) to boil a 60 degree F. pint of water. This would be the optimal stove.

How did I figure that?

Methyl alcohol has 10,200 BTUs per pound. A pound of alcohol is 19.5 fluid ounces, or about 585 ml.

A BTU is the energy required to raise the temperature of 1 pound of water 1 degree. A pint of water is about 16.7 ounces, or slightly over a pound.

So a 60 degree pint of water needs to be raised 152 degrees to boil. That means 152 BTUs are needed.

Divide 10,200 BTUs by 585 ml, and you get 17.5 BTUs per ml. Divide 152 degrees by 17 (to make it easy) and you get a result of 9 ml.

So if a stove is 100% efficient, it could boil a pint of 60 degree water with 9 ml methyl alcohol. Mine takes 12 ml, making it about 75% efficient.

A Trangia Westwind, in comparison, is about 60% efficient.

To show a comparison, a propane/butane stove has 25,000 BTUs per pound. Using the same math, it should take about 0.097 ounces of fuel to achive boil if its 100% efficient. The SnowPeak Giga stove actually needs .29 ounces, so it is about 33% efficient. If you take the mass of fuel my stove now uses, it needs only slightly more mass (.03-.08 ounces) of fuel to work than a canister stove despite the canister stove's higher BTU fuel.

Anyway. This may bore some of you or be over your heads. But to me it is a pretty exciting breakthrough. If it works as I hope it does on the trail, I've found my perfect stove.

[chris]

I am truly impressed by the science that is taking place in this thread! Although not directly related to the spririt of this thread, I do have a question about stove performance. I currently use the lower third of a beer can with some fiberglass insulation in it for a stove. Works fine. Fairly fuel effecient and reasonably fast. My question is, how much insulation is optimal for fuel effeciency? Loosely put it? Tightly packed? Happy medium? My guess would be that the more insulation, the better fuel economy but the lower heat output. I would also guess that SGT. Rock knows the answer to this question.

[SGT Rock]

Different stoves have different requirements, so there isn't a one size fits all rule.

But with a can stove like your using, I reccomend loosely packed for all aplications.

See, the fiberglass does do some wicking, so it actually reduces the amount of fuel standing in the center where you prime it. The benifit to this is it takes less time to boil the alcohol. When the fuel starts to boil, it vaporizes better and burns evenly. If you ever pay attention to the stove while it's burning you can actually here the alcohol boil.

Another benifit to the fiberglass wicking is it gets the fuel into the inner wall where it needs to be. Unce the alcohol vaporizes in a double wall stove, it takes time to transfer to the borner holes. By wicking the fuel to the outside walls, you speed this process. Depending on how well you pack the stove, you can see this happen within seconds of lighting it.

The third benifit that is hard to show unless you build a cat stove is the way fiberflass insulation acts when burned. It doesn't actually burn, but it can glow like a very dim lantern mantel. This helps to speed the heating of the alcohol, especially in cold weather. This really helps when using the stove in cold weather. Another trick I've found that helps is to put an insuator under the stove when using it in cold weather, but that is a whole nother thread.

But if you pack the insulation too tight, you either get all the fuel wicking into the walls and none is left to prime (this has happened to me) or you pack them so full that you clog the inner wall up too much.

[chris]

As I have a surplus of beer cans laying around, I think it is time for an experiment! Thanks for the answers.

[EarlyRiser]

you let us know if that stove of yours works, cause that sounds like a great lightweight stove. i dont currently own one so id much rather make one than to go out and buy a new one. especialy if itll save me weight (and from the looks of it, a lot of weight)

[SGT Rock]

I'm working on getting a trip going now. I'm thinking Ozark Mountains around Columbus day. I actually have three stoves that need a trail test:

Turbo V8 Micro
Trangia
Brasslite Solo

On top of that I have a Clark Hammock I need to trail test some more, another Hennessy on the way, and a new LED on the way.

Brfore ya'll get the wrong impression about me, I do not consider myself a gear head, I'm just a devil about the details. The funny part is I don't like to think about gear while I'm on the trail. I want to enjoy the hike. So I do a lot of preliminary testing here at home and get some ideas about things to try while hiking, then I go have fun.

It's like this. I hike all day, enjoying the trail and nature, friends and/or family, breeze in my face or ants carrying stuff across the trail, etc. Then its: "Oh by the way I need to cook my dinner tonight!" so I get a 7-15 minute test done, then it's back to watching stars, playing in the creek, hiking side trials, or taking a nap.

It ain't all about the gear, it is the hike. The gear is a means to an end.

[EarlyRiser]

well i for one appreciate the testing you do do. some people will try to sell their way of doing things and their gear but they dont back it up with facts or testing. you give us the details we need to make educated decisions for ourselves. thank you for your reviews they really help.

[The Weasel]

For those who are not aware of it, Ern - Sgt Rock - is recognized by no lesser authority than Backpacker Magazine as having home-designed and crafted stoves that are excellent. Am I right, Ernest?

The Weasel.

[SGT Rock]

I don't know if they recognized me. I sent in two during that alcohol stove cook off and never heard back. For all I know I did win, I rarely ever look at the magazine any more.

Anyway, something I was thinking about was re-naming the stove. I originally called my stoves the V8 stove because I got the idea for AYCE's V8 stove, mine was just a little souped up. Now I don't use V8 cans and they bear no resemblance to the old V8 stove at all. Early Riser gave me an idea for a new name - the Ion Stove. since Nasa has built their Ion drive on the principle of efficiency and low output to achive good results, I think my stove is trying to get the same efficiency in alcohol stoves.

Any comments?

Another thing, this thread originally started with me asking ya'll how you measure your stove's performance. I'm still interested in that. Like I said, I'm looking for total econemy of weight and fuel consumption, but to some people that doesn't seem to matter. If someone would prefer an alcohol stove that burns like a tourch I can go for that next, or if someone prefers the absolute lightest base weight, I can also do that. But in the end, what is most practical for your style and preference?

[The Weasel]

I specifically recall the results of the "stove-off" in Backpacker, with Sarge's stoves losing, but getting great reviews. Can someone confirm this for me? I don't have my old Backpacker's, but it was early this year, I think.

The Weasel

PS: Ern, If I'm right, you're even more famous, and you can even frame it!

[chris]

I have different scales for measuring stove performance based on what kind of trip I am doing. To make life easier, I'll just talk about how I measure performance during mild conditions, at low elevations, and at low lattitudes. So, any trip on the AT during April to October. In this case, my prime objective for the stove is to boil water, usually on the order of 1 pint, in a reasonable amount of time, with a reasonable amount of fuel. What is reasonable? Reasonable time is usually around 6-8 minutes, enough time for me to do some chores, like setting up my tarp, getting gear sorted, etc. Reasonable amount of fuel means around 1-1.5 oz. This means a bottle of HEET
will last me between 8 and 12 days, more than enough to reach a resupply point. In the end, I would trade off speed for fuel economy. I just don't seem to be able to build something like one of Sgt. Rock's stoves. Just mechanically disabled, I suppose.

Weight, price, and convenience are factored in to performance. White gas stoves lose out on all these counts during conditions usually met on the AT during the traditional hiking season, although they are quick and hot. Butane style stoves can be light, but they cost money and there are those annoying cannisters to haul around. Annoying for me, at least.

[slabfoot]

I test to determine if it meets my objectives.
1. is it easy to set up and use?
2. Is it as light as pactical
3. is it simple to construct?
4. will it provide long useful service?
5. will it help me fill my belly with a warm pot of food?
I've found that the light weight homemade stoves pass these tests well and I generally hike with a v8 or pepsi stove with aluminum flashing windscreen/pot support useing a walmart grease pot and a blue foam cozy. It has proven to be so simple to set and use that I have found myself cooking three meals a day and making hot drinks etc. for between meal stops. Ihave not subjected this system to winter weather but april through september have worked flawlessly. I will test this winter and let you know how well it does the job.

[Trail Yeti]

As Sgt Rocks "official" ;)long term field tester I got a couple of things to say. He sent me the "v-8 turbo" at Davenport Gap, TN. I started my thru-hike on March 10th,so I still had some pretty cold weather to try it out in. The only difference is it takes a little longer to prime, and you might have to use another capful of alcohol to get things going. Actually its more like 1/2 a cap. One thing I did do for when it was cold was this....
I bought a little 1 oz plastic screw bottle and would fill it up w/alcohol if the temps were going to be real cold. I put this bottle in a zip lock and put it in my pocket during the day or at the foot of my bag at night. I never had a leak, or if I did the alcohol evaporated so fast that I didn't notice it. Anyway, what this does is keep the alcohol warm (from your body heat) so that it doesn't take as long to boil and vaporize.
I use the top of my fuel bottle (empty coke bottle) as a measuring cup when filling my stove. 1 capful equals 1/4 of an ounce (about).
when using Sgt rock's stove I used about 1 1/2 oz of alcohol a day.
that includes cooking dinner, w/a hot drink for breakfast or after dinner. I was filling my fuel bottle about every 2 weeks (or sometimes longer in the summer) and even then I was never completely out of fuel.
the stove lasted the entire hike and I still even have the original windscreen!!!
so they do last and I was eating just as fast as the "hold-outs" who stayed w/white gas. However, by the end of the trail probably 90% of thru-hikers have switched to alcohol....why carry that extra weight?
so there is my two cents...
if anyone has any questions about Rock's stoves in "the field" I would be glad to answer them.
life is good, WEAR A KILT!
Trail Yeti
:p :confused: :eek: :rolleyes: :cool:
sorry, but i like the smilies!!!

[DebW]

I have both gasoline stoves (MSR G, MSR Dragonfly) and alcohol stoves (Trangia, Linguini Tuna Can). My problem is that I'm usually hiking with 1-4 other people so end up bringing the gasoline stove. On weekend family outings I may be cooking for 4-5 so clearly need the MSR. On longer section hikes of the AT, there are usually 2 of us and we like to cook together. Anyone had much experience cooking for 2 on alcohol stoves. I think boil times would be about 12-15 minutes for a quart of water. I do use a cozy.
What is the trade-off in cooking time and fuel weight when cooking for 2? Would we save weight cooking separately on 2 alcohol stoves rather than one gasoline stove? How about with 3 people? If none of you have done this calculation yet, guess I can do it myself and report.

[Trail Yeti]

Deb,
I never tried to cook for two on my hike....my pot isn't big enough for that anyway. My girlfriend carried her own stove and pot and cooked her own stuff. However, Papa Smurf and Flame made their meals together and they cooked on an alcohol stove...they used a cat stove w/a simmer ring and a pot cozy. Then one would eat out of the pot and they also had a little plastic bowl for the other.
I am sure there are others, I never got to meet them but I bet Jumpstart and Baloo did it.
hope this helps.
Yeti

[slabfoot]

last couple times out my hiking partner and i cooked for 2 on a pepsi stove wid no hitches. typically added 4 or 5 caps fuel to the pepsi burner and boiled 3 cup h2o wid 1 tablespoon powdermilk plus 1 tbs oliveoil and some lipton noodle entrees then added big foil pack of salmon, when boiling put in the pot cozy and ready to eat in 12 to 15 minutes. if you like them add 1/4 cup of dehydrated peeas and your on your way to some good trail food. for practical 2 person kit the walmart grease pot nests perfectly inside a generic 2 qt. aluminum pot wid wire bail and lid. stove wind screen/potsupport lighter and potgrip all fit inside. now wid that you can turn out 2 part meals or use one pot for hot drinks. Actually homade stoves are so lite and small each hiker can very easily have his/her own. You cook the pasta, I'll make the sauce works very well for us. good luck.

[SGT Rock]

Here is another question I can answer.

The more water you put into a pot, the ammount of alcohol needed rises at a curve and not a straight line. Heat and cold are not opposites - heat is energy and cold is the absence of energy. Heat seeks the area of lower energy.

1. The larger amount of water means there is more energy to transfer. The larger amount also typically has the same relative surface area of water to the flame as a smaller amount of water, so you get a relatively lower transfer. The principle is simmilar to why a block of ice will last longer than crushed ice of the same mass. There is more surface area for heat to transfer into the water in all those little pieces but not in in the one big piece.

2. There is more pressure at the bottom of a larger pot of water. Boiling cannot happen until the heat overcomes this pressure. This part of the theory I don't have a solid grasp on yet because I haven't educated myself to it. But I trust that it is true.

3. Alcohol stoves actually tend to take longer to reach boil with the same amount of water the more fuel you add. I have some theories on why, but suffice to say, it is true. You can look at all my stove tests on HikingHQ to see what I mean.

So if lower relative surface are and higher pressure means your fuel requirements curve, you have two options.

1. Cook in two pots simultaneously. When I take my kids camping we all have our own stoves. Making them is a family project we do together and everyone knows how to use them. Another advantage to this is it reduces the possibility of spreading bacteria. Since we all eat straight from our pots, the possibility of cross contamination is zero.

2. Get a stove that is more efficient and still cook together. There is a stove that I have actually found to do a very good job boiling two pints of water while maintaining good fuel economy. The Brasslite duo is the one alcohol stove I've found that actually works more efficiently. Because it works on a cool self pressurization system, the more fuel you add improves performance. It is the most expensive of alcohol stoves.

[jlb2012]

This evening I put together one of Sgt Rock's Ion stoves - mainly I wanted something less of a torch than the Turbo V8 to go with a smaller pot I just got. The V8 was great for the old grease pot from Walmart but the new pot was smaller diameter and the spread of flame from the V8 was too wide. The Ion stove worked well for me with the smaller pot - new pot is about .8L Ti somewhat similar in size to the MSR Ti kettle.

The assembly was not significantly different than the Turbo V8 but I had to guess what a "large paperclip" was in terms of size - my guess was one of the metal (chrome plated ?) paperclips in "standard" twice around form that is almost 2 inches long and not a butterfly paperclip which uses heavier gage wire and is closer to three inches long. Anyways the jets from the six holes were in good form and made good contact with the bottom of the new pot.

I made the Ion stove with the internal hardware cloth pot stand - I am still not sure whether to stick with this or to go back to the combined windscreen and pot stand type that I normally use. I like the combined windscreen and pot stand form because it is very stable. On the other hand the internal hardware cloth pot stand is not bad for a smaller pot and it has the advantage of conducting heat down into the pool of alcohol helping to heat the fuel before burning. One thing that I am concerned with is that the hardware cloth I used was galvanized - I think there is some health risk involved with heating galvanized steel but I am not real sure as to how risky this is compaired with say the risk of using methanol for fuel vs using denatured alcohol as fuel.

[Dirtyoldman]

Getting back to the original post I have refrained from an answer up till now because my testing has been evolving.

The testing to some degree has to be tailored to the desired outcome. Testing a blow torch is a bit different then testing for efficiency since the goal changes the data that you want to collect. You also end up restricting the test to the equipment that is availible.

For the first stoves I built, I only did a subjective test as all I was concerned with was if the thing could boil water. I was also changing wind screen designs so any hard data would be useless.

Now that I have a stable windscreen design and several working burners I test for both heat output and efficiency But I am reaching a point where I will have to get lab grade equipment and use much more strict procedures to get usefull results.

current testing...

timing - wrist watch rounded to nearest minute
measuring - kitchen measures,tin 1c and 1/8 c filled to brim
same windscreen and pot are used for all tests
water temps are not measured, two standards are used
boil - water noise in pot
steam - water vapor escaping from pot (true boil?)

and I also record the total burn time

up to now I have been using only 2 cups of water under ideal conditions with water of unknown tempature but trail conditions are rarely ideal. I have been toying with the idea of useing 3 cups to give a margin for lesser conditions but since noone else has posted this way I couldnt validate the data against anyone elses research. (it is good to have someone check your work) I guess a stop watch and a thermometer are next along with stricter procedures.


on the matter of minimal fuel to boil water the loss of efficiency occurs in several areas.

as the fuel burns btus are lost heating the burner,the alcohol, the air used, the windscreen, the potstand , the ground underneath as well as the pot itself. Also there is a loss when the heat is transfered from air to pot and then again to water. Add to all of this the pot radiates heat as does the windscreen. With all these losses going on its a wonder the water doesnt turn to ice! :D

[Dirtyoldman]

I just realised one bit of differance between our numbers...

You tested with 75 degree water (room temp) while I was useing 50 degree water from the tap.