Apr 6, 2013 at 11:46 pm #1301393
@drewjhLocale: Central Coast
I decided to try my hand at a dedicated esbit system for shorter or faster trips where I don't want to or have time to cook. I had purchased a ti wing stove and one of QuiWiz's new pot stand and burner combos but haven't tried them yet as I got a bit fixated on a Caldera-type setup. Here is what I came up with:
Sorry for the grainy pics (iPhone in low light.)
-Pot is a Ruta Locura 850 with carbon fiber lid. It measures 3.75" wide at the base by 4 5/8" tall.
-Windscreen is made from Home Depot aluminum flashing, and weighs 33 grams/1.16 ounces. Bottom diameter is appx. 5.5" and height is appx. 4 5/8".
-Distance from top of fresh esbit tab to bottom of pot is 1.25", 2.25" from the ground.
-The cone is covering the bottom 2.25" of the pot.
-Bottom of the screen has 3 x 3/8" holes on each side, spaced 2" apart. The bottom of the holes are spaced 1/8" from the lower edge. No intake holes on the front 1/4 of the screen so it can be faced into the wind. 3/8" just happened to be the punch I had laying around.
-Six 3/8" exhaust holes at the top. The top is a very snug fit around the pot (if you pick up the pot the screen comes with it.)
-For the tests I was using a gram cracker-esque ti burner that came with my QuiWiz Firefly. It holds the esbit tab 1/2" off the ground. And a 3×3 square of flashing under it.
I ran a number of tests this evening. Temperature was about 55-60 degrees with a fair bit of breeze on a couple of the burns. The stove was sitting on a concrete slab.
2 measured cups of cold tap water plus a dissolved ice cube boiled in 6:00-6:15, leaving what looked to be half of the .5oz esbit tab unburnt. I repeated this three times as I was tweaking the cone design (made several of them before I got the tab closure just right.)
After letting everything cool completely I attempted to boil another 2 cups/ice cube with the unburnt remainder. I achieved a full simmer at about 7.5 minutes and it held that until it burnt out at around 9.5 minutes. It got really close to boiling, equivalent to what I was seeing at about 5:45-5:50 with a fresh tab.
I put the other two remainder tabs on edge next to each other and boiled another 2 cups/ice cube in 5:50-6:00. That left a fair bit of esbit still unburnt:
The two partial tabs combined didn't burn as clean as a fresh tab. I was getting very little soot/gunk from the fresh tabs.
Then I tried 3 cups cold tap water with one dissolved ice cube. That boiled in 9:50-10:00 and left less than 1/4 a tab unburnt:
The stove/screen/pot were allowed to cool completely between burns.
After I cleaned it up:
The pot,lid,cone,burner,ground shield,sponge,tyvek cup,rubber band and GSI telescoping spoon (not pictured) weigh 4.865 ounces altogether.
I'm pretty happy with the performance, but don't really know what to expect from these systems. Is there anything to be gained by playing with the size/placement of the intake and exhaust holes and pot height? Also, is there lighter material than the flashing that doesn't overly compromise durability?Apr 7, 2013 at 5:23 am #1973605
@slammerLocale: Oklahoma Flat Lands
4.7 0z kit? Can't go wrong there! Although some will probably tell you to lighten it by 4oz :) Nice kit.
I'm an esbit user and finished a similar setup last night. Had very similar boil time. I have 28 1/4" holes punched in my cone 8 on the top edge. Seems like Esbit is sum what forgiving on airflow, pot height and wind.
By the way how was it in wind with the larger dia. holes?Apr 7, 2013 at 6:13 am #1973609
I'm using a ti wing setup w a thick aluminum foil wins screen and ground shield. I use the SP 700 with foil lid and handles removed. My kit is 4.1 oz before adding cozy and spoon. Fuel performance is similar to yours.
I have some aluminum flashing in the garage and I'm tempted to build a cone like this. Thanks for sharing!Apr 7, 2013 at 7:19 am #1973627
Hi, nice work. If you want some honest feedback I would say you need more ventilation holes in the cone, both top and bottom. If you look at some off-the-shelf designs you will see much more ventilation. I assume of course that this is the result of extensive testing on their part, I myself have not spent too much time experimenting. You may also notice that off the shelf designs often have about a third of the bottom of the cone without holes in order to provide wind resistance on that side; again, whether or not you agree with them is up to you. Lastly, I notice there is some puckering of the aluminium where you have punched the holes. This is down to the type of punch used. I find dedicated metal punches are paradoxically not very good at punching foil. This is because they are flat and simply press the holes out in one go, and this causes the material to bend slightly. If you tried to use that punch on ti foil it could make a real mess (you are going to tell me you have already done so and it works perfectly, oh well). I find the Mcgill 303 heavy duty paper punch is much better. The punch is diagonal, and cuts the hole progressively, leaving a nice smooth edge. Funnily enough I had to order mine from the USA. It powers through ti foil effortlessly. For my set-up I copied a design by Steve Evans, but I used an alloy beer bottle instead of a beer can, because they are more robust and don't require an additional container. The tall bottle is rather inefficient, but I need something compact to go with my flying gear. It holds several days esbit inside which is another bonus.
Altogether it probably weighs about 2-3 ounces and uses two 4g esbit tablets to boil 250 ml of water. Aluminium flashing from the diy store? You don't know how lucky you are in the US, you can't get that stuff for love nor money here in the EU. Below is a picture of my first cone, as you can see, the sheet metal punch has made a bit of a mess at the top of the cone. Not that I'm saying your holes suck or anything, clearly they are quite neat. I just think that that punch may come to grief on ti foil.
The burner, on the other hand, is rather smart: it was done with a simple paper punch; didn't even need the McGill 303 for that one. If you need a cone design program, there is a good one available on the Zen Stoves site. Have fun!
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