Model Forum / Radio Controlled / Air Models / May 2009

There is a small ethanol plant opening up in the area.  They built the plant
when gasoline was over $4 per gallon so I doubt they are doing very well
right now.  Anyway they might be interested in selling me a small quantity
of ethanol for trying out for model airplane fuel.  If it worked out I
wouldn't mind purchasing enough ethanol, oils, and nitromethane to supply
model fuel for the local area, they might even be interested in getting into
the model fuel business themselves since gasoline prices dropped.

I looked up info on the internet and there are suppliers for home fuel
ethanol production.  They have something they call a microsieve that takes
water out of alcohol and is reusable.  I thought if I could experiment with
Wal-Mart denatured alcohol it would be worth a try to blend my own.

RogerN

If I understand correctly, methanol is wood alcohol and denatured alcohol is
grain alcohol, i.e. ethanol.  I think from what I've read, they take
drinkable ethanol and poison it to make it non-drinkable and sell it as
denatured alcohol.  The ethanol plant in the area told me they have to mix a
certain percent gasoline in their alcohol, to make it not drinkable, before
they sell it.  Perhaps Methanol is used in model fuel because you can get it
pure since it's not suitable for drinking.

If ethanol would work for model fuel, a person can get a legal still and get
about 3 gallons of ethanol per bushel of corn.  It comes out of the still
about 96% IIRC and then run it through a microsieve to remove the remaining
water.  Anyway, there is a small ethanol plant about 20 miles or so from
here.  If ethanol would make good model fuel maybe they could sell me some
pure if I added nitromethane and/or oil before they let me have it.

The reason for my question is that I have some 30% heli fuel with 22% oil
content that I would like to cut to maybe 15% oil to use in model cars, if
denatured alcohol would work.

RogerN

Thanks, that's what I was wanting to know.  I knew there was something with
the platinum in the glow plug that causes combustion but I didn't know if it
worked with only methanol or also ethanol.

RogerN

I have run an engine on denatured alcohol- just briefly and by accident.

I was cleaning it and for some reason I attached a glow igniter- with
barely a flip of the prop it started right up- just burning the alcohol
in the carb and cylinder head- there was no fuel line connected.

Denatured alcohol has methanol in it.

A glo plug will work just fine with ethanol.  It will also work just
fine with acetone or lots and lots of other light organics.  That
catalyst on the wire is NOT specific to methanol.  In fact with
acetone you do not even need a precious metal.  A high temp copper
alloy wire would be fully adequate.  Something like monel for
instance.

The reason glo engines use methanol as fuel is all engines run on
heat.  So the more BTUs of fuel air mix you can stuff into the
cylinder per combustion cycle the more power you get out of the
engine.  It is simple high school chemistry to calculate if ethanol is
as good as methanol and it is not.  Nor is acetone.  But your engine
will run on either of them.  You might have to change the compression
ratio a little to get optimum performance from alternate fuels.  The
small amount of water in denatured ethanol is irrelevant.  The only
thing that matters is you must not have so much water in the fuel that
it causes the oil to separate.  If the oil stays in solution the water
makes no meaningful difference.  In fact tests on methanol based fuels
show slightly increased performance with a few % of water in the
fuel.  Those test results were published in one of the model mags a
few years ago.

So bottom line is if you do not mind giving up a little power lots of
alternate fuels will work just fine.  But every one of them will cost
you power vs methanol.

Now, if you do not want to give up power you could experiment with
real high nitro content ethanol.  But the cost of the nitro will drive
the fuel cost higher then methanol based fuel so why bother?  You
could also look at burning anhydrous hydrazine and get more power than
methanol based fuels.  Of course it is going to eat up your engine
pretty fast.  Still, you might get an hour or two out of it before it
was totalled.  Liquid ammonia is another possibility.  Same corrosion
problem and you also are dealing with a fuel tank under 40 or 50
psig.  Acetylene would be another logical choice.  Now you are dealing
with a possible explosion if you do not know how to handle the stuff.

Bottom line is methanol is the best overall practical choice for max
power output, ease of use, life of equipment and user safety.  If
there was a better choice the fuel manufacturers would be selling it.

It's been my experience that mixing your own, even with buddies involved to
split up expenses is not cost effective when you factor in the mess and
trouble. A 55 gal drum of menthol would require about 15 gallons of oil and
about the same in nitro (in 5 gal buckets). Then you have the storing/moving
the big drum around, mixing, minimizing exposure to air, getting 85 - 90
bottles, getting rid of the drums, etc, etc. Much better to buy as you need
it and eat the extra bucks a gallon. In addition, most commercial fuels have
other additives that don't normally get added in home brews.

If you are trying to dilute down a high nitro bottle of fuel, the easiest
way is to buy a gallon(s) of FAI (0 percent nitro) or 5% and blend together
as needed to get the reduction you want. Prolly would not have to bother
with buying extra oil, bottles or mixing equipment.

Just a thought......

Tom

You would be better off getting enough gallon jugs together to mix all
the methanol with oil and nitro. Leave very little air in the top of the
jugs, seal them, and store in a cool, dark place.

A friend of mine who inherited a drum of methanol
used nitrogen to pump the stuff out as needed.

He's an engineer who worked on oil pipelines, so
he knew how to handle the plumbing and keep things
safe.

I don't know what kind of fittings you'd need to
do the same or what the relevant safety issues
might be.

Good luck!

                Marty