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FAA Wants All Aircraft Flying On Unleaded Fuel By 2018
coondoggie writes "The Federal Aviation Administration (FAA) this week put out a call to fuel producers to offer options that would safely let general aviation aircraft stop using leaded fuel by 2018. The FAA says there are approximately 167,000 aircraft in the United States and a total of 230,000 worldwide that rely on the current 100 octane, low lead fuel for safe operation. It is the only remaining transportation fuel in the United States that contains the addition of tetraethyl lead, a toxic substance, to create the very high octane levels needed for high-performance aircraft engines. Operations with inadequate octane can result in engine failures, the FAA noted."
Now I know where I can get leaded gas for my old car. :) :)
Off to the airport.
If I were God, wouldn't I protect my churches from acts of me?
It's piston-engine stuff like Cessnas that make up the remaining leaded avgas users, and even there, only the subset of engines that require the 100-octane avgas. Both newer and some older stuff can use 91-octane stuff that's now unleaded.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
Octane rating... RON, etc...
So in 6 years, the FAA expects 167,000 aircraft owners to swap the engines in their aircraft for an unleaded engine? In 6 years companies are supposed to develop an unleaded engine that will fit in every type of small prop aircraft currently flying? Yeah, not happening.
And as a small single engine plane owner myself, I'll be damned if the government forces me to spend 30K on swapping out a new engine, then more on inspections and re-certification of the aircraft.
The people that own 6-cylinder engines are going to have the most issue finding a replacement. Most 4-cylinder engine will take auto fuel, but could need new fuel pumps/carburator parts that are able to survive in an ethanol world. The 6's just cannot make the same HP on the auto fuel they can on 100LL.
The Rotax 912 and Rotax 912s found in Diamond's DA20-A1 and DA20-100 are certified 91 octane unleaded fuel.
Now I know where I can get leaded gas for my old car. :)
Off to the airport. :)
I never got that. What's so great about lead in gas?
And in the meantime, it puts lead in the environment (gasp! I'm concerned about the environment!) , the refiners fought tooth and nail for decades to keep it in auto gas, and it causes lower IQ in children and m,any many other health issues.
Is your shitty old car worth it? Your old out of date technology - 19th century technology - car worth it? That piece of shit machinery?
Why don't you sell the piece of shit to a moron and buy a Tesla?
The issue is not with airlines (which use Jet fuel) or with Commercial operations (mostly using newer engines). It is with the flight schools and other General Aviation users.
The problem with leaded fuels is not really that technology to use unleaded is not available, but that most of the General Aviation Fleet that is flying is older technology. Majority of the GA fleet are from 1970's or 80's when Cessna and Piper dominated the market.
Then came lawsuits (frivolous and otherwise) and most of the manufacturers filed for bankruptcy. The airplanes from the 90s tend to be mostly homebuilt. Post 2000s a lot of the companies came back from bankruptcy and started making airplanes again. The only problem is that a new Piper costs about $200K while a perfectly usable 1970s Piper with overhauled engine and modern avionics is only about $30K. Airplanes last a lot longer than cars if regularly maintained. So most flying crafts tend to be old.
So these older planes which were designed for leaded gas get recertified for low lead gas, but can never use unleaded.
Newer aircrafts tend to do two things,
1) Run on motor gas (mostly involves certifying for unleaded gasoline) . This has the nice side effect that the gas tends to be about 30% cheaper.
2) Run on Diesel/Jet Fuel / Kerosine - In this case it sidesteps the entire lead problem and also avoids using spark plugs (depending on the design). Fuel availability is a lot better, though not always cheaper.
One easy solution is to make unleaded mandatory for any Light Sport aircraft (which tend to be the newer airplanes built) and to increase a fee imposed while overhauling older engines (which get done every 1000 hours).
That said, this move would permanently ground the WW2 display fleet that is currently flyable and a bunch of old Piper Cubs and Ercoupes. But they are all pre-ww2, so not a big loss I guess.
http://slashdot.org/submission/1062723/Cheap-mobile-data-plan?art_pos=2
No, and you can tell this from the first line in TFS: "The Federal Aviation Administration (FAA) this week put out a call to fuel producers to offer options that would safely let general aviation aircraft stop using leaded fuel by 2018."
They want fuel producers to offer options that will meet the need of aircraft that are currently dependent on leaded fuel to operate properly without lead.
I get that its a lot to ask you buy a new engine, or even to RTFA, but could you at least bother to read the first sentence of the summary before exploding with outrage next time?
Yeah, its a good thing that the FAA isn't talking about new engines at all, but instead calling on fuel producers to come up with replacement fuels that will work in current engines. Which is stated not only in TFA, which I can understand is a huge bother to read before complaining, but in the first sentence of the summary, as well.
I expect the authorities would make exceptions for warbirds... I'd hope so, at least.
Hail Eris, full of mischief...
E pluribus sanguinem
The removal of lead from automotive gasoline in 1976 brought about a very significant reduction in airborne lead, for which there was a risk of exposure by inhalation. There is little to no need for additional reduction to mitigate that risk. The only remaining serious risk of lead exposure is by ingestion of lead paint chips by children living in old houses. The FAA will need to be very careful not to increase the risk of aircraft engine failure beyond any possible mitigation of a minuscule inhalation exposure.
100LL avgas has over 20 times the tetra-ethyl lead compared to leaded automobile fuel. And that was after the TEL in 100LL was reduced by a factor of 2.
Airplanes last a lot longer than cars if regularly maintained
That might be true, because so many of them are mostly Aluminum, and Aluminum oxide protects Aluminum in precisely the way that Iron Oxide doesn't protect Iron. But it might not be, because who properly maintains cars? Washing the undercarriage regularly and so on? Pretty close to nobody.
this move would permanently ground the WW2 display fleet that is currently flyable and a bunch of old Piper Cubs and Ercoupes. But they are all pre-ww2, so not a big loss I guess.
Isn't it possible to produce conversion parts?
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
"Kittenman wants to win huge amount on lottery by 2018"
Yawn. We need less speculation and wishes in slashdot, more hard data. Well, that's my opinion.
"The greatest lesson in life is to know that even fools are right sometimes" - Winston Churchill
I used to do analytical work on fuel certification in a refinery, and while I didn't measure the "octane number", I understand what it means.
The number 100 refers to the performance of pure isooctane (2,2,4-trimethylpentane) as a fuel - isooctane is simply a reference for the "100" rating. Fuels are assigned a higher number when they are tested and shown to have a lower tendency to undergo premature ignition in an internal combustion engine (this phenomenon is known as knocking). Such premature ignition occurs when fuel and oxidant in a hot engine cylinder are compressed as part of normal operation of the engine and is more probable when the fuel has a lower activation energy for combustion and fewer radical scavengers are present in the fuel mixture.
Other compounds (aromatics like toluene and xylene isomers, tetraethyllead, methylcyclopentadienyl manganese tricarbonyl ) also enhance the "octane" number. The latter (MMT) is routinely blended into automotive gasoline in Canada despite being a known heavy metal/neurotoxin with likely worse long-term effects than tetraethyl lead (...!).
Among these various options, the straight hydrocarbons are far preferable and can be used without modification of engines to accomodate the exclusion of lead.
The only reason the heavy metals are used is to reduce the cost of filling one's tank.
I have read that such a requirement is going to be devastatingly bad for the current small plane industry. Most plane engines are built around leaded gas and cannot take anything but. Just another bright idea by our government that will hugely cost and destroy an industry.
> One easy solution is to make unleaded mandatory for any Light Sport aircraft (which tend to be the newer airplanes built)
I don't have industry figures but there are plenty of non-light-sport piston airplanes being produced these days too.. Cirrus, Diamond, and the remaining old guard companies like Cessna are still around and are not primarily in the light sport business. They're also producing higher performance aircraft that require engines that have classically run on 100LL.
Meanwhile, the overwhelming majority of light sport aircraft (>90%) use Rotax engines which already can run on unleaded. A bigger issue for those planes is that 91 octane unleaded is almost universally unavailable at airfields, so if you are unable to haul your own gas to the plane you are back to burning leaded gas.
Yes sure they can make an exception, but where would you then get the gas from ? You probably have to mix in lead directly in at the carb or something...
http://slashdot.org/submission/1062723/Cheap-mobile-data-plan?art_pos=2
They probably won't.
The FAA has a deep and seething contempt towards former military aircraft in private hands... above and beyond their general malicious contempt of aircraft in general in private hands.
I thought we were long past that!
If it is just an octane issue, then surely super unleaded and things like BP Ultimate and Shell V-Power would be fine?
When Canada phased out leaded gas some years ago, you could buy an additive for older engines that you just poured in the gas tank. So I imagine that something similar could be done for exempt aircraft. Mixing in a tank first would probably be much cheaper than modifying a carb and much safer.
> One easy solution is to make unleaded mandatory for any Light Sport aircraft
Bad idea, and totally not necessary. The majority of leaded avgas users are actually company planes, not Light Sport. With LS, we already can and do use unleaded pretty much as we please, except for one thing -- ethanol. Ethanol mixes with water and the vapor pressure is different. Airplanes go up and down in altitude which greatly affects vapor pressure and temperature. You can get vapor lock and frozen fuel lines. The way around the ethanol problem is pressurized fuel systems, but that's not anywhere near as easy on all light sport aircraft as it is in automobiles. The PROBLEM is that the EPA lets the corn industry run them around by saying that requiring fuel to be labelled as containing ethanol is discriminatory. So we don't know which fuels have ethanol in them at the pump! The simplest solution right now would be for the EPA to mandate that one grade of automotive fuel shall always be ethanol free and the problem would be pretty much solved for Light Sport. Simple stroke of the pen. But they won't do it for some unknown reason, most likely related to greed.
Plenty of old engines can get a supplemental type certificate (STC) to run on motor gas. The problem is that gasoline is hard to find these days. In Massachusetts, there is not a single service station, on or off airport that sells gasoline. They all sell gasohol, which is gasoline with 10% ethanol (or in rare cases MTBE) added. Every STC that I've seen specifically excludes fuel with alchohol additives. One reason being alcohol's affinity for water. You need to be able to separate out the water from the fuel and you can't do it if alchol is present. At high altitudes (cold temperatures), water, or hydrous ethanol can become slushy, clogging fuel lines and filters. Needless to say, that's very bad. Cubs and Ercoupes probably can run on motor gas (without alcohol), because they do not have high performance / high compression engines, and were never restricted to at least 100 octane fuel.
Actually, many of the old Piper Cubs and Ercoupes were designed to run on 80 octane (red) aviation fuel. They can run on ethanol-free MOGAS with no problems. The engines such as the TSIO-470 from the 1960s and 70s are the ones to be afraid of. Those will detonate very easily, even on 100LL.
Another minor correction: most engines today have recommended TBO times between 1400 and 2000 hours of service. If you do 14CFR91 operations only, you can go past TBO times legally. However, I would do so cautiously with regular oil analysis and frequent use of the aircraft.
Doing so might seriously help seriously update what's available under aviation standards, as the majority of FAA certified piston aviation engines are going on 40+ years obsolete by automotive standards. Also a lot of things considered problems in operating aviation engines would go away with direct injection, a turbocharger, and having mix control automated and controlled by a computer. (What's bad about a pilot having less shit to worry about?) Not to mention stuff like fault detection and diagnostics, and things like having "limp modes" to keep the engine running well enough despite some fault so you can get back home. (But at least an airplane engine should still have the guages or information display tell you what the fault is instead of the typical singular and mostly-useless "service engine" idiot light.)
Some stuff is stupid simple on an aviation piston engine, but a modern automotive engine still tends to do them a lot better. Also my guess is that modern automotive engines tend to go under more stress (lots of dynamic change in power and load) with longer maintenance intervals. Things on a 100,000 miles service interval probably adds up to more hours than the flight hours seen before a typical aircraft engine rebuild. Not sure if some of that is FAA being over cautious or automotive engineers are over-building their product with the (reasonable) presumption it's going to be thrashed and treated like crap.
Oh wait.. that has been done and is being done in race cars at the track, anda lot of people have made the switch to oxygenated fuels. Why not remove the lead, and add oxygen?
Just have them sell lead- and ethanol- free 91-octane gasoline at the airport, where they used to sell 100LL. Can even dye it a color and remove the road taxes while they're at it.
I would refuse a search and call my lawyer.
And for failing to comply with a "vehicle inspection" they may deny you the privilege of driving on a public road. Keep in mind, you agreed to certain acts of compliance in order to get your driver's license and in order to register your vehicle to drive on a public road. Calling your lawyer seems like an expensive way to get a ride home.
This would have been solved long ago if there was a easy answer.
Part of the problem is that most piston aircraft can use motor gas, assuming you can find some without ethonal mixed in. But only low compression/low power aircraft engines.
The smaller number of high power engines burn the bulk of the fuel and they require 100 oct.
The current system requires a seperate truck/tank/pump distribution network for 100LL and only a few refineries will make it. They have to flush the system before they can make anything else. It is a very small market compared to other fuels.
Yeah, not to mention the alcohol attacking fuel lines and bladders. Pretty much every aircraft with a composite tank is destined to fail at some point as the alcohol is one of the few things that can attack epoxy.
I own two aircraft. A 1946 Taylorcraft (think piper Cub, just better) and a 1967 Piper Comanche (4-place retractable. Fast. 260 HP fuel injected 540 Cubic inch 6-cylendar engine).
The Taylorcraft has an STC for unleaded auto gas of 91 octane or better (but see below). It runs quite well on stuff from the local unleaded pumps. The Comanche, with its compressions, could run well on 91 octane unleaded auto gas, but there is currently no STC to legally allow use of such fuel.
The problem with both is ALCOHOL!!! My autogas for the Taylorcraft must be alcohol free. Alcohol in the fuel does more than just degrade old fuel lines and fuel tanks.
Alcohol in an aircraft goes up and down over much more air-pressure and temperature varioation than does a car. Alcohol in fuel has led to many documented aircraft accidents and fatalities( See the NTSB reports over the years). Our fine government has mandated that the corn farmers deserve subsidies more than we deserve either fuel efficiency or safety (in the case of aicraft approved for unleaded auto fuel). i CANNOT find unleaded auto gas with no alcohol. Thus I still run 100LL in my Taylorcraft. I MUST by law run 100 LL in the Comanche.
If you will give me a reliable 91 octane auto gas replacement with no alcohol, and get the FAA to approve such gas in my Comanche, I will motor along happily.
There are still a large number of turbocharged high compression aircraft flying at 20,000' MSL that simply absolutely cannot operate on something with less detonation prevention that 100 LL. I will support those, my brethren, but for myself, if you will get rid of the insane alcohol requirements and get the FAA to cooperate, I will be glad to switch to unleaded.
Yes sure they can make an exception, but where would you then get the gas from ? You probably have to mix in lead directly in at the carb or something...
Lead additive was available for my 1966 car for quite some time after leaded gas disappeared. Plenty long enough for an engine rebuild -- a normal, wear-and-rear related rebuild -- with new seals, gaskets, etc.
I am not a crackpot.
Jet engines don't run this stuff anyway.. .They run on Kerosene.
It's all the prop planes that will have to follow this. I'm sure historic planes will still be allowed to run on current 100LL.
All the modern props will probably have to try and go after 93-96 octane car gasoline. Not a big deal. You will lose a nontrivial amount of fuel efficiency though.
Some of the aircraft engines in the piston GA fleet can tolerate lower-octane unleaded gasoline such as mogas without modifications. The Experimental Aviation Association has developed an STC that that permits the use of mogas in some combinations of aircraft and engines. Several popular engines, such as the Continental O-200 used in the Cessna 150, are on the list.
I fly a Cessna 150, and we have applied the EAA STC to our aircraft. Mogas can work just fine for normal operations and it's cheaper than avgas, but we run straight avgas after we've done certain types of engine work that require a break-in.
The real issue is that most of the avgas burned today is used by aircraft that have engines with large-bore cylinders and high compression ratios. They need the higher octane rating to prevent knocking. Engines like the Continental IO-550 have compression ratios of 8.5:1 or more.
Additionally, consider that all of the components of an aircraft's fuel system need to be evaluated. The fuel tanks, hoses, gaskets, pumps, valves and everything else need to be considered. A replacement fuel cannot have any adverse impact on the engine or the rest of an aircraft's fuel system. Performance with any replacement fuel must also be evaluated.
As for a replacement, if it eats away at the seals (like mogas with ethanol), it's unsuitable. If it shaves too much off of an aircraft's performance due to reduced power output or a weight difference, it's unsuitable. If it doesn't work with existing fueling infrastructure, it's unsuitable. If it costs too much to produce, and therefore will be far more expensive than what we have today, it's unsuitable.
http://en.wikipedia.org/wiki/Ferrocene
"Ferrocene and its derivatives are antiknock agents used in the fuel for petrol engines; they are safer than tetraethyllead, previously used.[34] It is possible to buy at Halfords in the UK, a petrol additive solution which contains ferrocene which can be added to unleaded petrol to enable it to be used in vintage cars which were designed to run on leaded petrol.[35] The iron containing deposits formed from ferrocene can form a conductive coating on the spark plug surfaces."
[added comment]
Just run them on nuclear already. It works for submarines, lol.
I'd love to use the STC on my aircraft and run something other than 100LL, but since Ethanol is mandatory in every gas station near me I have no other choice. 100LL fouls plugs, causes valves to stick and a ton of other issues. How putting that crap in autos ever became legal is beyond me.
I'd post on my account but once you've had a post labeled flamebait your account is pretty much doomed never to see the light of day again. Thanks Slashdot for never allowing an account to return to 0 even after a few years.
You are right about light sports. The only reason why people are not using automotive gas in them is that you can't, because at least here in CA it's cut with ethanol and ethanol (and the water dissolved in it) will ruin your engine and your day. Those newer engine actually run much better and cheaper (less spark plug fouling) on automotive gas, and they have been run like that for decades elsewhere in the world (i.e. most of Europe).
The new Cessna 182 that can use Jet-A and the light sports and experimentals that can run on 91 octane unleaded are essentially in the noise in terms of total number of aircraft being produced.
Continental has expressed interest in licensing Safran's diesel engine technology for a wider range of output power. The engine is expensive enough that it may take a decade before a significant portion of light aircraft are diesel powered, though the price differential and Jet-A may encourage a fair number of engine swaps. 'Course this still leaves out the folks with big honkin' radial engines...
A Shadeless room is a brighter room.
It's not.
The reason aircraft engines are built so very simply is for reliability. Everything you add is just another thing to malfunction. When you are 1500' in the air, over a city, you have pretty much no wiggle room. Find someplace to land now! At 1500' you have less than a minute to get it figured out and and around 1 more minute to get the thing on the ground.
MANY people have tried to adapt car engines to GA aircraft only to see them fail, time and time again. Cooling problems, vibration problems, fuel problems, you name it.
Diesel engine technology is being heavily tested and one or two have even entered production, but those have a very long way to go before they can be said to be reliable. And that is reliable to a standard that everyone can basically bet their life on, not just the pilots, not just the passengers, but people just like you, living your life peacefully until that airplane comes through your roof.
For any airplane to fly it is always the weight -v- lift -v- drag -v- power trade off.
I would love to adapt a Ferrari flat 12 for aircraft use. It runs on unleaded, meets California smog rules, you can get LOTS of horsepower out of 5 liters ( 12 cylinders ). Basically you get 480hp and 480 foot pounds of torque at about 6800 rpm and when you reduce that to 2400 rpm or so you 480 foot pounds * ( 6800 / 2400 ) and you can go really fast.
Hey KID! Yeah you, get the fuck off my lawn!
Right, let's get rid of lead in fuel. Why should the electronics industry be the only one to suffer from the over-zealous war on lead?
While the health effects of lead absorption are well understood, methods for absorption are not so much, and in the meantime we're substituting for it with stuff that is likely much worse. And making future generations pay with all the failed electronic devices we're throwing out in the meantime...
"Nine times out of ten, starting a fire is not the best way to solve the problem." - my wife
seriously, why are they still using leaded fuel? ô_0
Private pilot (PP-ASEL) here.
I am certainly NOT the 1%. Learning to fly is not more expensive than a LOT of other hobbies. The very first time I flew in a small aircraft was as passenger with a student, who certainly wasn't rich (very old scrappy car; that was in Germany - so he didn't have to pay high tuition fees), he tried to get acquaintances to fly with him and share some of the cost of most of his flights.
Hourly costs sound high, but that is the time the engine actually runs. If you do aerobatics instead of (extremely boring) cross-country flights very few if any of your flights will be longer than an hour - and that's more than enough for the weekend, it's quite exhausting. That's roughly $200/week.
You CAN spend unlimited amounts of money, same as in sailing/yachting, but you also CAN participate in these hobbies on a limited budget.
That said, I stopped flying, part of it was THIS (article) and the noise my airplanes create. When I hike through Yosemite (or anywhere) the last thing I want to hear is small aircraft noise above, but it's sooo common these days. I just don't want to be that guy.
I also stopped horse riding, for similar reasons, but for the horses sake: I did not want the responsibility of owning one, and I don't want to support the horse industry where most animals spend almost all their time in small boxes. Those animals need lots of space on grass land, that's rarely what they get, at least not close to large cities (I did most of my riding in the SF Bay Area, some Oakland Hills stables) where there are lots of people keen on riding but not enough space to give horses a natural environment. Both flying and riding are VERY fun hobbies, unfortunately there is a considerable cost - to others.
If my studies and testing of home produced ethanol (dry 200proof, non-denatured ethanol) made from various farm carbohydrate sources ar accurate i consistently get an RON of just over 110.8 and an MON of above 90.5 yields an octane rating of higher than 100 (R+M)/2. The 'denaturating' with a iso-paraffinic kerosene (renewable turbine fuel) and adjustment of actual octane rating with a minute amount of 2,2,4-Trimethylpentane (iso-octane) which is already common with gasolines can readily make these 'older' aviation systems safe and lead free with very little difficulty.
As for the food vs fuel and other FUD surrounding ethanol production - although outside the scope of this conversation - the ages old dual-stage fermentation with aspergillium varieties which is used for making sake, soju (shochu) and awamori, can convert many simple and complex polysaccharides and starches into fermentable sugars without needing malting or easily fermentable glucoses. It's not switchgrass on my farm, but guinea grass, sedges and less woody vetch does consistently yield in excess of 10% ethanol by weight. A poly culture of a. nigrens and a. aspergillus is the best performer in my shed. We run a new Toyota truck, and old Nissan Pathfinder, a diesel 'mule' farm tractor with PTO's for mowing etc, the weed whacker, and our house 'jennie' all off the drier field 'hay' which the goats dont care for as much as the green. The 'it takes more energy to make than you get' is just more FUD, as without any input from the gas pump we only make seasonal batches and store the excess for regular use.
IIRC - there are aircraft companies who have studied and are committed to using ethanol or methanol for their fleet operations in the coming years. A little govt encouragement by way of simply outlawing toxic lead in all airborne pollution would put a fix in quick.
In Sweden we use 91/96 unleaded without any problem It is a drop in replacement. The Pawnee in my gliding club never had any problems running on 91/96 so I guess that most of the US fleet could use the same unleaded avgas.
Change to Propane (110 octane) or LNG (octane 130). Though probably have to retrofit underwing or tip tanks (already some types on market). Both are much cheaper fuels, and engines could be made higher performance with higher compression ratios.
I got that scary feeling because I had only read the first four words. It was slightly less scary when I managed to read the fifth word. I hate it when can't see the title due to other windows blocking my view.
now we need to go OSS in diesel cars
I guess they gave up on that.
It is scandalous that this took so long to do...
I know Europe and USA measure octane differently but still your fuel seems to suck. In Finland you have a choise between RON 95, 98 and E85(RON106). As a turbo enthusiast I would never use anything below RON98 and I've been very happy with E85.
another power mad three letter agency.
Until the three letter agency problem is solved: Re-elect no one.
The other thing is that auto gas has various aromatic compounds (e.g. containing a benzene ring, although they don't use benzene) added to it to improve the octane and other properties. That's why it hasn't smelled like "gasoline" (or naptha, to use the right terms) for decades. Autogas also contains oxygenates in most parts of the country (ethanol, thanks to the corn industry, or other things) to reduce CO emissions from cars that are running rich. Not to mention proprietary additives (detergents, etc.) . The net is that auto gas tends to smell more like paint thinner.
Avgas, because they can use TEL to boost the octane, is much simpler: It's basically a blend of hexane, heptane and octane to get the right boiling points for the season, plus the lead to get the octane right.
Compare the smell of gasoline, avgas, and coleman stove fuel (aka "white gas", so called because it's straight refinery naptha with no additives or dye). You'll find that the stove fuel has that familiar gasoline smell of yore, and smells a LOT like avgas, and nothing like the paint thinner smell you find in your car.
Aluminum oxide is tough and tends to prevent oxidation of deeper layers. Iron oxide is very weak, much larger than the metallic iron it replaces, and doesn't prevent oxidation of deeper layers.
Contribute to civilization: ari.aynrand.org/donate
Reading comprehension? You fail it.
Aluminum oxide protects Aluminum in precisely the way that Iron Oxide doesn't protect Iron.
Aluminum oxide is tough and tends to prevent oxidation of deeper layers. Iron oxide is very weak, much larger than the metallic iron it replaces, and doesn't prevent oxidation of deeper layers.
Thank you, please drive through.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The gas engines used in general-aviation aircraft are basically 1930's technology, frozen there by the combination of a small market and the high cost of updating them. Also, paradoxically, aviation manufacturers are afraid to improve their products because of never-ending product liability concerns (Lawyer: "Aha! So the very fact that you improved the bolts holding the wing on 10 years ago means that you must have KNOWN they were defective in my client's 40 year-old plane! Ten million dollars, please.") Aviation gasoline will eventually go away. Today's engines may be replaced by a new generation of aircraft diesels burning jet fuel, which is much more readily available.
Actually octane requirements go down with altitude. Reduced atmospheric pressure reduces the tendency to pre-ignite (ping). Gas sold at altitude is lower octane than gas sold at lower altitudes and is posted as such on the pump.
...huh? Do you need a hug?
Why yes, I AM a rocket scientist!
gosgog:
I owned an old Cessna 170 B, one time (remember Nixon & the U.S. WAS RUNNING OUT OF OIL??), I was flying a job between Houston, San Antonio and Areas around, Photoing Oil and Gas drillings and got low on fuel, three airports had no 80/87 Octane, and finally I landed close to Lethbridge, used the airport loaner car, and a five Gallon Gas can, pulled into a local shell station and bought unleaded gas and refilled my Tanks, the old bird flew just fine on it. It was cheaper back then than avgas, so I used the auto fuel more often. NO PROBLEM, ( I'd use the old 170B 60 - 80 hours a month. The story that was talked about, burning my 170 B continental engine valves etc....BULLSHIT! HOWEVER, I was told later by a kid who raced hot rods on 100Low lead avgas, that it had a tendency to burn valves in auto engines.
It won't ground Cubs and Ercoupes, most of them will already run happily on mogas and actually do so (so long as it's ethanol-free. unleaded mogas sold at an airport is ethanol free but not many airports sell it). The engines in Ercoupes and Cubs are low power, low compression and just don't need the lead - in fact the lead is actually harmful to them (spark plug fouling, lead deposits etc).
Oolite: Elite-like game. For Mac, Linux and Windows