T o d d P a t t i s t wrote:
"Sport Pilot" wrote:

Alcohol is completly soluable in gasoline, in fact adding a small
amount of gasoline to model airplane fuel is sometimes done to improve
starting and increase engine heat during the winter. The confusion is
that you can also mix water gas and alcohol and have the three
completely disolve. So why didn't the water disolve into the gas and
alcohol mixture?

A typical gasoline-alcohol automotive fuel blend can
dissolve water up to only about 0.6 or 0.7% at 70=B0F. Beyond
this the water forms a separate layer and the alcohol
preferably is dissolved in that layer.

Has anybody verfied that this method works all the time? I have a
hunch the rusults can vary depending on vibration and temperature.

If the maximum 0.6 or 0.7% water/gas/ethanol blend at 70=B0F
is cooled, both the water and some of the ethanol become
insoluble in the gas. The result is two layers of liquid -
an upper ethanol-deficient gasoline layer and a lower
ethanol-rich (about 75% ethanol) water layer. If more water
is added, the lower layer of water increases in volume and
continues to preferentially dissolve the ethanol.

The test method uses 10% water, far more than the maximum
that can be dissolved in the gas/ethanol blend, so it always
forms two layers and sucks the alcohol out of the gas.


Do not spin this aircraft. If the aircraft does enter a spin it will retu=
rn to earth without further attention on the part of the aeronaut.

(first handbook issued with the Curtis-Wright flyer)

I have done some research also, alcohol is NOT completly soluble in
gasoline, it varies with temperature and gasoline composition. It is
especially not soluble in cold weather. The reason the gas disolves in
model airplane fuel is that the castor oil is soluble in both methanol
and gasoline.