> Paul,
>
> It is not correct that range has to suffer by burning
ethanol. In
> fact range can increase if you fly above 10,000 ft density
altitude.
>
> The reason is that ethanol has an oxygen content of about 25
> percent. The effect is like supercharging, or nitrous oxide, or
> dragsters that use nitromethane which has huge amounts of
oxygen.
> Gordon
Sorry, this is not correct -- the oxygen in ethanol is
representative of
the fact that is has been partially oxidized, in other words,
partially
burned. So some of the energy content has been expended over
being a
hydrocarbon. Nitromethane is a different story. The oxygen can
come free
of the nitro-groups and combine with any available hydrocarbons.
You carry less energy per pound with ethanol, how you use it
determines
your specific fuel consumption, milage, etc.
The evaporative cooling effects and octane effects are real,
but the
oxygen content has already been used up ( i.e. not available).
Bill Schertz
Bill,
Thanks for that insight.
What exactly do you mean by, "partially oxidized?" The way I
understand it pure ethanol has an oxygen content of 35
percent, so
all of that oxygen should be available for oxidization, no?
(AGE 85
is only 85 percent ethanol -- the rest is pentane isomerate -- so
its oxygen content is about 30 percent.)
The oxygen is the reason the stoichiometric air-fuel ratio of
ethanol is lower than gosoline -- because when you add the same
volume of air, there is more total oxygen due to the oxygen
embedded
in the fuel, so you need more fuel to completely oxidize the extra
oxygen. See the attached table, "Ethanol Gasoline Properties."
The heat energy of ethanol per pound or per gallon is lower than
gasoline, as you pointed out. However, the oxygen in the ethanol
results in better thermodynamic efficiency, so power actually goes
up. You can see in the attached chart that an O-470 engine
running
on AGE85 has 15 percent more peak power.
The graphic on flight test data shows that at 10,000 feet a Mooney
with an IO-360 running AGE85 has a fuel burn at lean mixture
that is
less than the same plane on avgas at 8,000 feet. One of the
advantages of ethanol is that very lean mixtures can be safely
run.
Regards,
Gordon.
Gordon,
What adverse effects are there on housings when you use
Ethanol ? I had
developed and manfactred seals which resist methanol and
future long
life oil detergints. These could be used on a rotary engines too,
however I had the impletion that Ethanol, Methanol etc corrod the
housing.
regards
Roderick
Roderick,
As far as I can find from the literature, AGE 85 is compatible
with
existing fuel system materials.
Here are some snippets from I think Baylor University which
has lots
of info on AGE 85.
Regards,
Gordon.
Gordon,
While I'm sure the info you provided about operation at 10K and
above
is true, I must interject that most of my local flights would be
over
before
I even got to 10K feet! Lots of local fun flying never exceeds 4K.
One other item that is rotary specific, does anybody know if
there may be
mixing trouble if you run fuel/oil mix? I'm NOT stating this, I
don't know.
I'm not a chemist and I don't even play one on TV.
Bill Jepson
for FKM Polymer seals is definetly not true.. I full time job is as
Operations Manager at Trelleborg... and Seals are designed for
specific fuels, and chemicals, we have a large range of FKM seals
designed form specific enviroments, being it temp, oils, fuels etc.
Never assume that all FKM compounds are the same.
Sorry for correcting your info source, but EP is usually used for water
and Braking seals which temp does not exceed 140C, NBR - for ligh oils
which temp does not exceed 125C, and FKM for Fuels. FVMQ - id good for
all but its cost is about 10 times more.
check out our web site at
www.trelleborg.com <http://www.trelleborg.com>
Roderick Scotto
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.