[at-l] Homemade Alcohol Stove

["Mayer, Jim" <JMayer@crt.xerox.com>]

All this talk about Esbit stoves got me playing with an alcohol stove design
again.  I've used a Trangia "Westwind" stove for a year or so now, and have
been quite happy with it.  It isn't, however, the ultimate "lightweight"
stove... for one thing the burner seems to be made of solid brass.  The
Westwind stove and stand weighs about 6.6 oz, and with a windscreen I get up
to 7.4 oz.

I've tried burning alcohol in a 3oz tunafish can, but the open flame just
doesn't seem to generate enough heat.  I don't think it burns very
efficiently.  I've tried a couple of designs off the net that haven't quite
seemed practical either.

However, I finally put something together that feels "trail worthy".  I
haven't TRIED it yet under field conditions, but I'll describe it briefly
here.  Please note the "DISCLAIMERS" section at the end of the message.

Weight (burner, stand, windscreen) 2.8 oz.
Boiling time: 2 cups cold tap water, covered pot, indoors: 5 min 20 seconds
	[boiling time is from lit match to boil... no priming]

Materials:
	3 oz tunafish can
	aluminum oven pan liner
	small amount of fiberglass insulation
	hardware cloth (1/4 inch mesh, stiff)
	aluminum foil
	rubber band

Directions:

THE BURNER

(1) Take the top off the tunafish can and eat the tunafish.

(2) wash the can out well

(3) cut a strip of the oven pan liner long enough to go around the can, and
exactly the same height as the can.  Cut a few tiny (1/16 to 1/8 inch high)
triangular notches in the bottom of the strip.

(4) Take a small amount of the fiberglass insulation and line the inside of
the can.  You don't need much.

(5) Roll the strip of aluminum up and place it inside the can.  Expand the
roll to make a ring.  There should be about a 3/16 inch gap all around the
ring (the gap to the outside of the can is about 1/4 inch).  The fiberglass
should be lightly compressed between the ring and the can. 

(6) Make a small (3/16") cut where the strips overlap and fold the strips
over.  This will hold the ring in place.

(7) Put a flat, hard, object on top of the burner and press down so that the
ring is level with the top of the can.

The burner is now complete.

THE STAND

Cut a piece of hardware cloth and fold over the sharp edges.  Join the ends,
either by folding or by weaving in some wire to form a ring with the
following dimensions:

	Height: 2 1/2 inches
	Diameter: 4 1/2 inches

On mine I folded the ends in opposite directions to make an interlocking
joint.  With the folded back ends, my piece is about 14 1/4 inch long.

I don't think the hardware cloth will stand up to a lot of bending, so I
just put the whole stand inside my pot.  It fits inside nicely.

THE COVER

Make a little aluminum foil cover for the burner out of a couple of layers
of aluminum foil.  Bend it over the top of the tunafish container and hold
it on with a rubber band.

THE WINDSCREEN

Mine is 4 inches high and a bit over 21 inches long.  If I was to make it
again, I might make it a few inches longer.  It is made from two pieces of
oven liner bottom.  I folded over the cut edges (to make a smooth,
reinforced edge) and punched a lot of 1/8 inch holes in the bottom for
ventilation.  The ends are bent back in opposite directions so that they
hook together, although in the past I've just used a paperclip.  I joined
the two pieces with this weird aluminum tape that is sold for use with
"Reflectix" insulation...  I suspect you could just roll the two ends
together and hammer the joint flat.

The "right" size for the windscreen has more to do with your pot than the
stove.  Mine is sized to fit around a 1.3 liter Evernew titanium pot.  The
height is set so that the handle of the pot clears the windscreen.

USING THE STOVE

Pour a small (1 oz? experiment!) of denatured alcohol into the burner.  Most
will get soaked up by the fiberglass (it acts as a wick).  Light the stove,
put the stand down, set up the windscreen, and put the pot on top. 

NOTE: As the stove heats up, it will run more efficiently.  When it gets
going, I see a column of blue flame going strait up from the burner and up
around the bottom of the pot.  If you see yellow flames the burner isn't
getting enough air.  Going to a slightly higher stand might help... I
experimented a bit to come up with a height that seemed to work well.

Cook.

I'll bet you think the aluminum foil cover is to put out the stove.... well,
you're wrong.  You can try, but all I managed to get was flames shooting out
the sides.  The best way to put the stove out is to fold up a WET bandanna
and scrunch it down over the flames.  Make sure the bandanna is wet, or IT
WILL BURN.  You can put the stove out by taking another can that fits
loosely over the burner, but they you have to carry it. It would make a nice
case though, particularly if it had a plastic snap on lid.

There will probably be no fuel left in the bottom of the burner.  If there
is, you can pour it back into the fuel bottle.  But if you put out the stove
before it burns out, there will still be alcohol trapped in the fiberglass.
The cover is to keep the stove together and to reduce the smell of the
unused, trapped, fuel.

I've tried placing the stove on top of a piece of "Reflectix" (basically
aluminum foil covered bubble wrap".  It worked fine and didn't melt the
plastic.  It is probably better to just put the burner on a rock, or to
scrape away any "duff" to make a safe surface to run the stove on.  If snow
is a possibility (I wouldn't call this a winter stove) you might want to
bring something to put underneath.

CARRYING FUEL

The best way I've found to carry fuel is in 4, 8, or 16 oz wide mouth
Nalgene bottles.  They are completely bombproof, and are pretty light.
Narrow mouth bottles work well too, and are easier to control, but harder to
fill.  I prefer the wide mouth bottles.

ABOUT ALCOHOL STOVES

Alcohol has about half the "oomph" of gasoline.  If you are running the
stove for a long time (e.g. melting snow, cooking for three, etc.) you might
find that the higher energy of a gasoline stove means you have to carry less
fuel.  I find I can get by on about 1 oz per day with my Trangia, but I only
fire up the stove for dinners.

An alcohol stove has one safety advantage over gasoline stoves, and two
(smaller) safety disadvantages.  The big advantage is that alcohol and water
mix, so you can put an alcohol fire out with water.  Gasoline floats on
water, which makes it difficult to put a gasoline fire out.  The
disadvantages of this kind of stove are that if you knock it over the fuel
spills (not much of a problem with this design since most of the fuel ends
up trapped in the wick anyhow), and that burning alcohol doesn't give off a
lot of light.  When you first light the stove, don't assume that it isn't
lit just because you can't see a flame (particularly in daylight).  Always
feel for heat first.

DESIGN NOTES

I'm sure the above design can be improved.  I haven't spent a lot of time
refining it.  In particular, I suspect something more clever could be done
regarding the stand.  On the other hand, the hardware cloth is light, cheap,
and seems reasonably sturdy.

The real "trick" here is using the fiberglass as a wick.  I saw the
suggestion elsewhere as an alternative to using "Perlite" in the little
popcan stove whose design was on the web.  In comparison to that stove, this
one is sturdier (the tuna can is much stronger than the bottom of a pop
can), easier to make, easier to fill, and easier to light and, at least a
first glance, faster.

Happy Holidays.

-- Jim Mayer

DISCLAIMERS

I HAVE NOT TRIED THIS IN THE FIELD.

DON'T BURN DOWN YOUR HOUSE.  ALCOHOL IS FLAMMABLE.

*** NEVER *** TRY TO BURN GASOLINE OR ANY OTHER PETROLEUM PRODUCT IN AN OPEN
STOVE LIKE THIS.

YOU ARE SMART!  IF SOMETHING DOESN'T MAKE SENSE TO YOU, OR SEEMS DANGEROUS,
THEN DON'T DO IT!

I, OF COURSE, TAKE NO RESPONSIBILITY FOR ANYTHING I SAY OR DO.


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