Gasahol -- where are the problems going to be?
Jim Weir
should have made that decision for yourself using common sense.
Instead, for those of us who have made the decision based on the lead-fouling
(and cost) parameters of 100LL, it appears that we have another decision to
make.
MTBE is nasty stuff. California, in it's legislature's infinite wisdom, decreed
that MTBE should be used to oxygenate winter gasoline. Brilliant. Save the air
and poison the wells. Not clever. Now it looks like everybody is veering in
the direction of an ethanol-gasoline blend to do the job.
As those of us who have the STCs know, gasahol is NOT a permitted fuel under the
provisions of the STC. However (especially in the center third of the country),
it looks like getting pure gasoline is going to become rather difficult.
Given this scenario, let's start to think about where we are going to run into
trouble. Yes, I've seen the scare pictures of an o-ring turning into a gummy
donut after immersion in gasahol, but that is hardly what I would call an
academic test. And, at what level of ethanol does gasahol start giving us
problems? 0.001%? Probably not. 50-50? Probably so. And, where are those
problems going to be?
Let's go from the filler neck to the exhaust system. First, at what point do
bladder cells start to break down under gasahol and in what period of time?
That is, if I run a 5% gasahol trip over a weekend and fill with pure gasoline
when I get home, what level of deterioration might I expect?
Quick drains have O-rings, as do gasculators. Can we use a different material
o-ring that alcohol doesn't attack?
Flexible fuel lines. Anybody ever test a fuel line with gasahol?
Carburetors. I know the needle has a neoprene part, but is neoprene attacked by
gasahol? Can we reengineer the needle? Are there other gaskets and such inside
the body that will deteriorate? Which ones? At what level? And why don't
automotive carburetors frap up with gasahol, especially old ones?
I'm not aware of any injected engines that are eligible for the STC. If anybody
else knows of one, what injector parts might be harmed by gasahol? And the same
automotive question as above?
Are any of the valves or exhaust parts alcohol sensitive? Why? And what can we
do about it.
Just some idle thoughts on a warm summer's day...see you all at The Show in a
couple of weeks...anybody taking a guess at the Oshkosh weather this year?
Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com j...@rst-engr.com
Margy Natalie
Jim Weir wrote:
>
> Just some idle thoughts on a warm summer's day...see you all at The Show in a
> couple of weeks...anybody taking a guess at the Oshkosh weather this year?
>
Three days of intense heat followed by 2 days of torrential thunderstorms and mild
flooding, finishing with a few days of chilly weather. Departing VFR briefing,
ceiling 1,500' visibility 3-5 in haze and light rain. Have a nice flight!
Margy
George R. Patterson III
>
> And, at what level of ethanol does gasahol start giving us
> problems? 0.001%? Probably not. 50-50? Probably so. And, where are those
> problems going to be?
Back in the 70s many stations in Georgia started selling gasahol that
was 10% alcohol. Many of the automobiles of the day had problems. The
most commonly mentioned problem was failure of fuel pump diaphrams. I
had no problem with the old Ford I drove at the time, and we never put
gasahol in my wife's Opel.
The Pilot gas station chain had so many complaints that they quit
selling gasahol and put up big signs stating that their gas has no
alcohol. How many of those complaints were based on fact and which on
rumour is unknown. At the time, the law required that pumps had to be
labeled if gasahol was in the tanks. I don't know if this is still the
case, but I still see the labels when I'm in Carolina or Tennessee.
George Patterson, N3162Q.
Rod Farlee
>Carburetors. I know the needle has a neoprene part, but is neoprene attacked
These are all good questions.
Neoprene is more resistant to ethanol than it is to gasoline.
All the aircraft O-rings I've used come in labelled packages with MS
numbers and are identified as Viton or buna-nitrile, also no problem.
Fuel hoses are teflon lined, no problem.
http://www.efunda.com/DesignStandards/oring/oring_chemical.cfm?SM=none&SC=
Ethanol#mat
I dunno what O-ring materials Cessna might have used 30 years ago in
their fuel selector valves, etc., but some have never been replaced.
- Rod
Kyler Laird
subject instead of my misuse of "ethanol" but I
want to be sure that I'm being correct here.
AGE-85 is what I would call an "ethanol blend".
80-90% fuel grade ethanol
10-20% pentane isomerate
0.5-1.0% biodiesel
I don't know anything about pentane isomerate.
Does it qualify as the "gas" in "gasahol"?
Jim Weir <j...@rst-engr.com> writes:
[lots of good questions that I've been trying to
get answered too]
I've had a hard time getting current information
on this subject in rec.aviation.*, so I decided
to do something novel - I went to the source for
current info on AGE-85.
My first discovery is that they call it "AGE-85"
(not "AGE85"). My search results were incomplete
before. Now they include the AGE-85 home.
http://www.engineering.sdstate.edu/~ethanol/
(Obviously they're putting more effort into their
certification program than their Web site right
now, but it does have some good info.)
Dr. Dennis Helder was kind enough to send me some
rough slides that have more in-depth information.
I have made them available at
http://www.ecn.purdue.edu/~laird/ethanol/AGE-85_slides
These include details such as the power curves
(which are interesting because AGE-85 yields more
torque at a given speed for a fixed pitch prop).
>Given this scenario, let's start to think about where we are going to run into
>trouble. Yes, I've seen the scare pictures of an o-ring turning into a gummy
>donut after immersion in gasahol, but that is hardly what I would call an
>academic test. And, at what level of ethanol does gasahol start giving us
>problems? 0.001%? Probably not. 50-50? Probably so. And, where are those
>problems going to be?
It looks like the 85% mix of AGE-85 is not a
big problem. Dr. Helder writes
Generally the only thing you have to do is
increase fuel flow to get a 10:1 air/fuel
ratio. Practically, this means rejetting a
carburetor or recurving your fuel servo if
you have an injected engine. You also need
to insure material compatibility on older
aircraft.
(Since we have manual control of the air/fuel
ratio, that's not much of an issue. Material
compatibility is the key.) His mention of
"older aircraft" has me curious. Is my 1966
Aztec an "older aircraft"? What's the key
change in materials?
>Let's go from the filler neck to the exhaust system. First, at what point do
>bladder cells start to break down under gasahol and in what period of time?
I'm willing to test this. I have a couple of
bladder cells that I am willing to donate.
They need to be patched, but they should
serve the purpose. How would you like to do
it?
>Quick drains have O-rings, as do gasculators. Can we use a different material
>o-ring that alcohol doesn't attack?
Note that for the C-180 conversion, the only
replacement mentioned is
Fuel bladders were replaced with new
nitrile rubber bladders.
>Flexible fuel lines. Anybody ever test a fuel line with gasahol?
only simple modification to fuel
system required
I'd guess that this means increasing max.
flow rate.
I might have some lines I can donate for a
test.
>I'm not aware of any injected engines that are eligible for the STC.
It's being pursued. The 1982 Mooney 201 they
acquired has a Lycoming IO-360.
>Are any of the valves or exhaust parts alcohol sensitive? Why? And what can we
>do about it.
Again, this would fall under my definition of
"major modification" so I'm *guessing* that
it isn't an issue with AGE-85. They say it's
being developed "for use in _any_ piston
aircraft".
Note also these impressive claims.
no carburetor or fuel line icing
run rich or lean with no detonation
dual fuel -- blends with 100LL
5-10% more mid-range torque
cleaner engine operation
cooler engine operation
up to double TBO
added altitude performance
Sounds pretty incredible. I'm looking forward
to being able to try the real stuff.
Because it only has around 88,200 BTU/gallon,
one of the usual downsides is that it
decreases range (when contrasted to 100LL). I
run rich in order to keep my turbocharger
temperature down. Because the cooling effect
is based on flow and because AGE-85 burns
cooler than 100LL, I might not pay nearly as
much in range. (I'll just waste fewer
potential BTUs.)
For non-turbo planes, being able to run leaner
(without detonation) and at higher altitudes
could offset this, too. In the C-182, the
difference is 1 GPH, so I suppose it's not a
big deal anyway.
BTW, I called Dr. Helder on the phone and
although he was in a meeting, he was quite
congenial and interested in talking more on
the subject. I just wanted to get his
permission to share the information he sent
me, but he did mention contacts here at
Purdue. I mentioned someone who played
down the use of ethanol blends because of
"vapor lock" and he simply said "That's why
we need to get this information out there."
(It's going to take a lot of education to
overcome the FUD out there.)
Another thing to consider...
At a federally-funded airport, what are the
barriers to a group of pilots getting
together to purchase a fuel truck, becoming
trained in its use, and then filling their
own planes with AGE-85 that they purchase?
I thought of doing this with 100LL back
when there was a thread on the subject, but
it seems that with AGE-85 there would be no
issue of competing with an FBO (unless the
FBO carries it).
I plan to talk with Dr. Helder next week.
I'll be happy to ask your questions and
report back here.
--kyler
Mike Spera
After my wife and I saved $2300 that year burning Amoco regular vs avgas, I was
interested in continuting to do so. But, the corn lobby put the squeeze on the paid
off Illinois politicians and pure gasoline went bye bye. Anyway, what follows was a
query to the EAA from me. They were testing gasohol at the time with the FAA and
appeared to give up. Be sure to read the EAA reply to the my message (following it).
It is very interesting. I was surprised with the fuggitabboutit attitude from an EAA
guy. They usually stand tall for cheapskates like me. I felt a little betrayed that
they gave in so easily. I don't care about a price differential of even $.50/gal,
but a buck spread means $1000 saved a year for me. That's an annual and a set of new
tires/tubes with a new battery thrown in to boot.
I just tanked up 2 weeks ago with autogas (sans alcohol) at Pontiac (Il.) airport
for $1.90/gal. The local airport (Schaumburg) charges close to $3.00/gal for 100ll.
Yeah, the stuff stunk like hell when I sumped it. I saved $27 for that one fill up.
It felt like old times...........
Mike
> -----Original Message-----
> From: Mike Spera [SMTP:mws...@wwa.com]
> Sent: Wednesday, September 08, 1999 8:32 PM
> To: info...@eaa.org
> Subject: Alcohol Oxygenates in Auto Fuel
>
> Folks,
>
> Your information concerning ethanol in auto fuel states that you and the
> FAA have concluded that extensive modifications would need to be made
> and therefore you have discontinued testing for ways to use auto fuel
> with ethanol.
>
> Well, that just about makes auto fuel STCs of no value in 99% of the
> U.S.
>
> Please explain what "extensive modifications" mean.
>
> I recall a major university study that found little ill effects when
> using ethanol in aircraft engines. Were they full of beans, or is the
> EAA and FAA being unnecessarily over cautious?
>
> Thanks for any insights,
Dear Mike: Just keep burning 100LL and you will have no problems with
ethanol. In other words, forget about autofuel and go on your merry way.
Life is too short to let such problems get in the way. All the very best,
Norm Petersen.
Norm Petersen
Sr. Aviation Information Specialist
EAA Aviation Information Services
Phone: 920-426-6806
Fax: 920-426-6560
Jim Weir wrote:
> This thread is NOT to convince you to use autogas in your airplane. By now you
> should have made that decision for yourself using common sense.
>
> Instead, for those of us who have made the decision based on the lead-fouling
> (and cost) parameters of 100LL, it appears that we have another decision to
> make.
>
> ..............questions about ethanol/gasoline and other stuff Jim asked snipped
Roger Houston
I had read in (the ac-flyer?) that a new ~92 octance straight unleaded Avgas
was going to be unveiled later this year or early 2002...
Orval Fairbairn
<SPAMSTOP...@hotmail.com> wrote:
According to the refining experts I have talked to, gasoline can be
refined to about 93 octane without additives (unleaded).
It will certainly be more expensive than either unleaded mogas or 100LL,
but it can be transmitted through existing pipelines, unlike 100LL, which
requires too much buffering to prevent contamination.
As for gasohol, expect about 10% increase in fuel consumption, due to its
lower energy density.
Kyler Laird
>According to the refining experts I have talked to, gasoline can be
>refined to about 93 octane without additives (unleaded).
O.k., everyone go read this.
http://www.nexusmagazine.com/ulp1.html
Wait until you're done reading it to go to the
magazine's home.
http://www.nexusmagazine.com/
Giggling is o.k., but if you don't agree with
the article, please supply some evidence to
support your assertions. I'll appreciate some
good counterpoint to it. (I've asked before
and gotten none.)
>As for gasohol, expect about 10% increase in fuel consumption, due to its
>lower energy density.
Am I the only one who wastes 100LL BTUs in
order to keep the engine (turbo) cool?
--kyler
Russell Kent
> As for gasohol, expect about 10% increase in fuel consumption, due to its
> lower energy density.
This flies in the face of the evidence. Chevron states that the gasohol should
have only 2%-3% less energy per gallon, so the fuel consumption should increase by
the proportionate amount.
http://www.chevron.com/PRODSERV/GAS_QANDA/OXYGEN.SHTML
[seems to be out-of-service; see the Google cached version at:]
http://www.google.com/search?q=cache:1xK9g9OBSdE:www.chevron.com/prodserv/gas_qanda/oxygen.html+www.chevron+gasoline+ethanol+energy&hl=en
Russell Kent
Orval Fairbairn
Perhaps it is their mixture, vs other mfgs' mixture. The end result is:
if you plan to use gasohol in your plane, expect to have higher fuel
consumption, and plan accordingly.