The problem isn't so much the energy density as the fact that ethanol has some nasty reactive propeties part of which is because it's hydroscopic and part is that fuel systems weren't designed to encounter it. This has been a big concern in the boating industry where WATER is a more invasive problem. The sad truth is aviation fuel tends to sit in tanks a lot (avgas is specifically stabilized) which car gas is not and it gives the ethanol time to attack the tanks, etc...
Using ethanol in any engine AND airframe combination that has not been designed for it, TC'd or STC'd is not only illegal but it is the equivalent of playing Russian roulette. An Experimental category aircraft can burn any fuel, otherwise it is not legal to use and ethanol blend unless it is approved and listed in the engine/airfram TC and/or STC. The effects of ethanol are cumulative, and all it takes is one batch to start the deterioration of incompatible parts. Even if all your materials can handle E10, how do you know that the fuel you are buying is not in fact E15 or even E30 ? There have been plenty of documented cases of gas stations selling much higher levels of ethanol than permitted, and no state does testing - it is simply left up to the buyer to beware.Quote:
Originally Posted by mmorrison123
You will find mogas prices at airport in AirNav's statistics:
http://www.airnav.com/fuel/report.html
Mogas is selling, on average, for $1.50 less than Avgas. When you buy it at an airport, you can be assured that it is aviation-grade, the best being 91+ AKI, ethanol and lead free, low RVP vapor pressure, filtered in aviation grade filters. Anything you buy at a gas station is a risk, so make sure you check every batch for ethanol even if it is listed as being ethanol-free. Buy from branded dealers and try getting the highest AKI rating, 93 is best, since generally the higher the AKI the better the fuel quality.
Even if you could make an O-200's many parts (especially the carburetor) compatible with E10, when the fuel sits in the tanks or carb bowl for a week or more, the ethanol in the fuel is absorbing water from the atmosphere. Eventually you will have phase separation, and now that water/ethanol mixture will begin to eat its way into all the materials it touches. It is a highly-corrosive chemical that has been known to eat right into composites and elastomers, causing them to swell or turn into a stick goo that will eventually find its way into your engine. If you are lucky, it will happen before your reach an altitude when they subsequent engine failure or fuel fire will kill you.
The solution is simple - work with your local airport to bring high-quality mogas directly from the fuel terminal to your airport. Trucks delivering fuel to your local gas stations probably drive near your airport weekly. All terminals have ethanol-free fuel since that is where the ethanol is added to the ethanol-free that comes out of a gasoline pipeline. When you use fuel from a gas station, you are paying highway fuel taxes - that does not help our airports. When you buy it at an airport you are paying into the aviation funds and they need every penny these days.
This is not entirely accurate. Water is a problem for boats and aircraft due to the open-vented fuel systems used, not because they are operated near water. Modern cars, by contrast, used closed, pressurized fuel systems so there is less water absorbed from the atmosphere. Statistically, private boats and airplanes are operated about the same annually, around 50 hours, the rest of the time they sit in a hangar, shed, etc. If fuel remains in the system, and it contains ethanol, it will eventually reach saturation and phase separation occurs. The resulting ethanol/water mixture sinks to the bottom of fuel tanks, lines, pumps, carbs, etc. and starts eating into the surrounding surfaces.Quote:
Originally Posted by FlyingRon
Quality gasoline without ethanol (aka Mogas) has a stable shelf-life of about one year. Avgas shelf life is 1-2 years. Put ethanol in gasoline, or in 100LL for that matter, and the shelf life drops to a few weeks.
Great info guys. I'm just trying to fully understand the issues. All I have to go by is my personal experience and what I can find in the media. My 180 hours flying in the past 4 years comes very close to the 50 hour per year that was mentioned as an average for airplanes. 95% of that was using car gas with ethanol (10 or more percent, I'm not sure). I use the same fuel in my mowers, snowblower, power washer, and weedeaters, all of which have open-vented fuel systems. I never drain the tanks or use Stabil during the off seasons. And I'm not aware of a single issue that I'm experiencing due to ethanol phase separation or damage to fuel system components. Again, I'm not saying that it isn't occurring, just that if it is, I can't see any indication.
I think that the simple solution of getting mogas delivered to all our local airports might be a little more difficult than stated. Wouldn't the airport need some type of approved fuel tank and delivery system, separate and in addition to what they already have for avgas. I know when one local airport installed such a system for avgas it was very expensive. Since I'm the only one at my airport using mogas I doubt I could talk the owners into investing in this.
Again, this is all great info about what ethanol could do, but is this really what ethanol does? So far we have a Cessna, Kolb, and Phantom with fuel tanks made from unknown resin (was it epoxy, polyester, vinylester) that experienced terrible, sometimes immediate deterioration due to ethanol. What is different about their situation than mine, and are there others out there that are using ethanol blend with no apparent problems? Once again, just trying to educate myself.
I sugest You to check Brazilian experience about fuel with ethanol. There are a experience greater than 30 years whit
mixing up to 25% ethanol in the auto gas and many pilots flying with experimental airplanes whit this fuel whitout problems.
In some situations, a lot of ag pilots flying their agricultural airplanes (certified) with pure ethanol. I personaly test all
parts of my fuel thank (using litle parts of it) submersed in pure ethanol for more than 6 years without signs of corrosion,
included in this test a rubber fuel pump diaphragm. I flow with pure ethanol arround 200 hours in a experimental airplane
equiped with VW engine witout problems. My unique prevention is a separate fuel tank with avgas for start and stop
engine, it means that fly intervals, all the fuel sistem rest with avgas.
Your experience is quite the exception. Read the thousands of comments on this petition to the EPA, asking that premium fuel be excluded from ethanol blending. Many document costly damage to their engines, including the complete loss of aircraft. http://pure-gas.org/petitionQuote:
Originally Posted by mmorrison123
Fuel equipment does not have to cost $100,000 or more. There are plenty of good, surplus military aviation fuel trailers available for pennies on the dollar. If airports want pilots to continue flying, they will eventually see that mogas is the only way to significantly reduce the cost of flying. When avgas disappears as it has in most places outside the US and Europe, the only fuel will be mogas, but without ethanol.
Brazil is another story altogether. It has cheap ethanol which is a great incentive to go through all the trouble of making it work in aircraft. Experimental aircraft can burn anything, but this does not eliminate the problems ethanol blends cause. I understand that in Brazil the Ipanema crop duster and a special Lycoming engine have been certified to run on 100% ethanol. When however the owner of the plane produces ethanol from the sugar cane the crop duster sprays, it is obviously more economical to try using the fuel. But I doubt that many pilots in the US would want the trouble of having to drain the fuel tanks and fuel system any time the plane is not being operated. The Brazilian company Aeroalcool tested a number of engines running on 100% ethanol and developed Brazilian STCs for them. I understand that Aeroalcool could not make a business from this as Brazilian pilots burn ethanol despite not paying the money to Aeroalcool for the STC. Do that in the U.S. and you face serious consequences from the FAA and your insurance company when something goes wrong. Eliminate the government subsidies and mandates for ethanol in Brazil and the biofuels industry will likely collapse as it is in the U.S. now. I would not want to invest in any technology for an airplane based on a fuel that only exists as a result of a government program.
So far, I have observed damaged tanks with Vinylester, Polyester, and Epoxy resins. Most alcohol "resistant" slosh compounds will protect the resins and tolerate some exposure, but won't stand up to long term exposure. Many of the MS carbs have composite floats in them that also may not tolerate ethanol. As far as we know, it won't damage an O-200 to run on alcohol contaminated fuel or anything else that burns as long as it can avoid detonation. However, for the long term, you need to eliminate most plastics, rubber, neoprene, cork, composite resins, and aluminum from your fuel systems, and then run a closed fuel system (as opposed to an open vented fuel system) to avoid drawing water while in storage. If you can do all that and don't mind carrying the weight associated with that type of fuel system, then your O-200 will probably be happy to burn the fuel. But, as a practical matter, 100LL and Ethanol Free gasolines are a much more practical solution.Quote:
Originally Posted by mmorrison123
-CubBuilder
Thanks for the link to the pure-gas.org petition. I spent some time looking at the comments from my home PA. I even recognized a few of the names, but believe it or not, I'm still skeptical. A vast majority of the hundreds of comments seemed to echo what ethanol could do, or state why they desired pure gas, or state that ethanol was just plain a bad idea. There were some comments that spoke of costly repair bills and destroyed engines, but I just haven't had the same experience, nor has anyone else that I know. Our lawn mowers, cars, power washers, snow blowers, and ultralights are all still running. Perhaps they are not running as well as they used to but I can't tell. Maybe my gas mileage is down, I'm not sure, but it's not down 40% as some in the petition are claiming. I don't think that my experience is the exception at all. As far as the vinylester fuel tank that was damaged by ethanol, I would really like to learn more. Many of us homebuilders have hung our hat on the supposed fact that vinylester will hold up to ethanol. If this is not true it is very important. As for the fuel truck/trailer, that's what one local airport used to use, but some govt organization, I'm not sure if it was the EPA,FAA,DOT or whom, told them it they had to but in a permanent approved (expensive) tank.
Go visit KRNet.org. A very meticulous builder hung his hat on vinylester being impervious to alcohol. He never even got in his first flight before he had a gascolator full of brown goo followed a couple of weeks later by fuel seeps from the tanks. Now his plane is down while he builds aluminum tanks.Quote:
Originally Posted by mmorrison123
Some of the spun polyethylene tanks such as those found in some lawn mowers and weed eaters do indeed seem to tolerate ethanol. That has been my experience as well. The question is, do you want to find our what does and doesn't work while you're in the air?
You've asked for anecdotal evidence that there are problems with ethanol. Folks here have shared their knowledge and experience with you. You choose not to believe them. So why did you ask?
-CubBuilder