GAMI presentation from OSH '24

[A64Pilot]

1 hour ago, redbaron1982 said:

Something I can't understand is why airplane engines are considered "high compression ratio"  when they are (give it or take it) 8.5:1, and all modern cars are at least 9:1. Even old engines, like the Ford 302, were, I think, 8.7:1 without the help of any ECU.

So is the problem a combination of compression ratio + CHT? Hypothetically, if we had better cooling and an airplane engine would run at the temperature a regular car engine runs, could we use regular mogas?

It’s several factors, but primarily it’s that our combustion chambers etc are essentially the 100 year old Hemi design. Compounded by the fact that our pistons by Auto standards are huge, which means very large combustion chambers, size matters because the speed the flame front travels is fixed, so more time to completely combust in a large chamber.

Then compounded by the huge safety margin required, as in 500F cyl head temp, extremely hot intake air and excessive high oil temp etc., plus the absence of any protection system like a knock sensor etc means a relatively low compression engine has to have excessive octane.

IF someone were to build a modern four valve head that allows for a Pentroof combustion chamber and ran smaller cy bores then we would do fine on Auto fuel.

To get to four valve engines on motorcycles required liquid cooled heads, I assume that would hold true for Aircraft too.

In short Auto engines have continued to evolve tremendously, heck Mazda has or will soon introduce a gasoline, spark ignited Diesel if you can image that, where we literally still fly behind our Grandfathers engines.

https://www.mazdausa.com/discover/mazdas-skyactiv-x-breaks-cover#:~:text=The SKYACTIV-X engine uses,completely than in conventional engines.

https://www.mazdausa.com/discover/what-you-need-to-know-about-the-compression-ignition-engine

[Shadrach]

2 hours ago, N201MKTurbo said:

I read a book many years ago about motor fuels. It was written in 1923. 101 years ago! There is little we are talking about now that isn't in that book, including the ingredients in G100UL. 

It's not that we have some new modern chemical technology that will save the day, it comes down to what compromised we can live with.

https://books.google.com/books/about/Motor_Fuels.html?id=DHBBAAAAIAAJ

George has openly stated that G100UL started with a high octane, unleaded formulation that I believe was experimented with in the early 40s but was not fully developed because at the time, TEL was easier, cheaper and more practical. Much of GAMI/APS/TAT’s successes have come from modernizing and implementing what was well understood 80-90 years ago.

[MikeOH]

42 minutes ago, Shadrach said:

There is nothing exact in his statement… It is non-specific, philosophical speculation being thrown from the cheap seats. There is no substantive argument. Its all feelings…Oddly emotional for an engineer…

WOW!  Talk about 'emotional'!  Me thinks you doth protest too much.

Of course I don't have 'specifics'; none of us do. I'm speaking as a rational engineer that has seen that any engineering design is a compromise with trade-offs.  We, and maybe even George, do not necessarily even know all of them.  Whether or not he is deliberately hiding info is certainly speculation.  But it wouldn't be the first time a company held back deleterious information about their own product.  Tell me, if we were accusing Phillips Petroleum of such tactics would you be as outraged?  Or, would you be jumping on board in agreement that they were hiding info?

As far as a 'chemical miracle' I'm glad you agree that it is not; so why the animus towards anyone that suggests that it isn't?  It's good science to question data and absence thereof. Also a really good idea to repeat the 'experiment' by many people over a longer period of time.  I.e., plenty of real-world field testing.  My points most certainly ARE SUBSTANTIVE ARGUMENTS; not mere 'philosophy.'. To call my comments 'rocks from the cheap seats' is truly the emotional refuge of desperation.

Look, 100LL is going away.  I'm against the 'ban' until an alternative fuel is FIELD PROVEN over at least several years.  I don't care if it's G100UL or something else.  All I am certain of is that it WILL cost more per gallon.

[Shadrach]

8 hours ago, MikeOH said:

WOW!  Talk about 'emotional'!  Me thinks you doth protest too much.

Of course I don't have 'specifics'; none of us do. I'm speaking as a rational engineer that has seen that any engineering design is a compromise with trade-offs.  We, and maybe even George, do not necessarily even know all of them.  Whether or not he is deliberately hiding info is certainly speculation.  But it wouldn't be the first time a company held back deleterious information about their own product.  Tell me, if we were accusing Phillips Petroleum of such tactics would you be as outraged?  Or, would you be jumping on board in agreement that they were hiding info?

As far as a 'chemical miracle' I'm glad you agree that it is not; so why the animus towards anyone that suggests that it isn't?  It's good science to question data and absence thereof. Also a really good idea to repeat the 'experiment' by many people over a longer period of time.  I.e., plenty of real-world field testing.  My points most certainly ARE SUBSTANTIVE ARGUMENTS; not mere 'philosophy.'. To call my comments 'rocks from the cheap seats' is truly the emotional refuge of desperation.

Look, 100LL is going away.  I'm against the 'ban' until an alternative fuel is FIELD PROVEN over at least several years.  I don't care if it's G100UL or something else.  All I am certain of is that it WILL cost more per gallon.

As far as I can tell you have done zero research on the one replacement that has been through the STC process (twice) and has currently been flying in multiple GA aircraft (both turbo and NA) for several years and hundreds if not 1000s of hours. You don’t appear to know anything about the supplemental type certificate or the process that went into approving the fuel. Why do the home work or better yet actually engage the developer when you just “know” generally speaking based on your expertise that GAMI is holding back and or obscuring the negative aspects of this fuel.  So yeah, you are throwing rocks from the cheap seats as you’ve not articulated a single specific area of concern. 

Speaking of which, I do have a concern regarding G100UL but it has nothing to do with functionality. It has to do with how it might interact with well preserved, acrylic enamel paint on vintage birds. 

[Shadrach]

44 minutes ago, A64Pilot said:

In short Auto engines have continued to evolve tremendously, heck Mazda has or will soon introduce a gasoline, spark ignited Diesel if you can image that, where we literally still fly behind our Grandfathers engines.

https://www.mazdausa.com/discover/mazdas-skyactiv-x-breaks-cover#:~:text=The SKYACTIV-X engine uses,completely than in conventional engines.

https://www.mazdausa.com/discover/what-you-need-to-know-about-the-compression-ignition-engine

And yet there are only a handful of modern spark ignition engines that will match our dinosaurs in terms of BSFC.

[MooneyMitch]

I WAS enjoying this thread ! Careful gentlemen please . 

[N201MKTurbo]

1 hour ago, Shadrach said:

George has openly stated that G100UL started with a high octane, unleaded formulation that I believe was formulated in the early 40s but was not fully developed because at the time, TEL was easier, cheaper and more practical. Much of GAMI/APS/TAT’s successes have come from modernizing and implementing what was well understood 80-90 years ago.

I believe the high octane, unleaded formulation is alkylate. Which is the base stock for 100LL.

https://www.afpm.org/newsroom/blog/alkylate-understanding-key-component-cleaner-gasoline

[N201MKTurbo]

100LL is Alkylate + TEL

UL94 is Alkylate

G100UL is Alkylate + aromatics (toluene, xylene, etc.)

I predict we will end up with UL94 and detune our engines. 

[Shadrach]

1 hour ago, N201MKTurbo said:

100LL is Alkylate + TEL

UL94 is Alkylate

G100UL is Alkylate + aromatics (toluene, xylene, etc.)

I predict we will end up with UL94 and detune our engines. 

I hope not.
A later model 2900lb, 201 is already near the year round limit of what’s practical from power to payload ratio. I recently flew to Niagara with my plane full of family, bags and 50gals of fuel. OAT of 94° and a departure DA of ~3000’ at 300msl. It reminded me of why I rarely fly in the dog days of summer…It turns my airplane into a dog. I don’t want to give up any power.

[1980Mooney]

7 hours ago, redbaron1982 said:

Something I can't understand is why airplane engines are considered "high compression ratio"  when they are (give it or take it) 8.5:1, and all modern cars are at least 9:1. Even old engines, like the Ford 302, were, I think, 8.7:1 without the help of any ECU.

So is the problem a combination of compression ratio + CHT? Hypothetically, if we had better cooling and an airplane engine would run at the temperature a regular car engine runs, could we use regular mogas?

 

6 hours ago, redbaron1982 said:

That's not was not my thought, I'm just wondering why a 1960's Ford 302, with a compression ratio of 8.7:1 can run mogas and a Lycoming IO360, with a compression ratio of 8.5:1 cannot.

 

5 hours ago, Shadrach said:

No one runs a car the way that we run our aero-engines, ,....

This is probably the most overlooked factor when anyone tries to compare an air cooled aircraft engine to a liquid cooled solid block automobile street engine.

Rarely would your old Ford 302 be running WOT -it might be measured in mere seconds - hardly even for one minute for an automobile.  Maybe in a truck application, usually derated, it might run WOT for longer periods. But our aircraft engines run WOT for hours on end.

Why does that matter?  Manifold pressure.  A car cruising at 60 mph on a level road, no wind, might have the throttle open 1/3 or about 30-35 degrees.  Engine vacuum might be 16-18 inches HG which is about 12 - 14 inches HG Manifold Pressure in our aviation lingo at SL (that is only 6-7 psi). A Lycoming IO-360 at SL WOT might be 26 inches HG Manifold Pressure at 2,500 RPM dropping to 18 inches at 10,000 ft. (that is about 13 psi at SL and 9 psi at 10,000).  If the pressure is double, then the air density (number of molecules is double) and since the air/fuel ratio is in a narrow range, the number of hydrocarbon molecules is double burning with double the energy.  So with the same or similar Compression Ratio to the Ford 302, the Peak dynamic cylinder pressure of our aviation engines are much much higher than typical car engines - double at SL.  Yes the manifold pressure drops on a NA engine as altitude rises but even at 10,000 ft cruise we still have more peak cylinder pressure than a car cruising a level freeway at SL.  - probably 30-50% more.  More cylinder pressure.  See the Savvy graph below.  A 20% increase in manifold pressure resulting in a 49% increase in measured peak cylinder pressure.

The TN engines that are at 30 inches HG all the time or turbocharged with over boost hitting 40 inches.  Yes they have slightly lower static Compression Ratios in order to manage peak cylinder pressure but the turbocharged engines with 1/3 greater boost will hit the highest pressure of all.

In addition to higher pressure, the air cooled engine has more hot spots - a solid liquid cooled block has better and more stable heat transfer.

As @Shadrach and @A64Pilot said other variables that affect this are ignition timing, valve timing, mixture.

This is a good read - https://www.savvyaviation.com/controlling-the-combustion-event/

Edited August 7 by 1980Mooney

[tony]

3 hours ago, Shadrach said:

There is nothing exact in his statement… It is non-specific, philosophical speculation being thrown from the cheap seats. There is no substantive argument. Its all feelings…Oddly emotional for an engineer…

I didn't read any emotion in Mike;s statement at all.  I thought more that he has 40 years of engineering experience discovering other people's undocumented features late in the design cycle.  

[Shadrach]

6 hours ago, tony said:

I didn't read any emotion in Mike;s statement at all.  I thought more that he has 40 years of engineering experience discovering other people's undocumented features late in the design cycle.  

Ok then, this begs the question what would be satisfactory? The fuel has 100s if not 1000s of hours of testing on the most sophisticated aviation engine test stand available...anywhere.  It has gone through two STC applications and met all standards for approval each time through two different FSDOs.
No one here has articulated an actual technical concern with the fuel, just concerns about product development as a process in general. Either there is a standard or there isn’t. If there is, either that standard has been met or it hasn’t. In this case there is a standard for STC approval. If one has an issue with said standard or the process in which approval was granted, then make it known.  “I am sure there is something wrong with it because there have been things wrong with other things at other times that I have observed ” is a lousy argument.

[N201MKTurbo]

2 hours ago, Shadrach said:

I hope not.
A later model 2900lb, 201 is already near the year round limit of what’s practical from power to payload ratio. I recently flew to Niagara with my plane full of family, bags and 50gals of fuel. OAT of 94° and a departure DA of ~3000’ at 300msl. It reminded me of why I rarely fly in the dog days of summer…It turns my airplane into a dog. I don’t want to give up any power.

I would like to win the Power Ball too, but it doesn’t mean it is going to happen.

There is no reason to lose much power. Only takeoff and initial climb. With something like a SIM, you could take off with reduced power and in cruse and climb for that matter. Your power can be restored. 
 

Let’s say you have to detune a 200HP engine to 195Hp. (That’s still more than a G model). And this was done by retarding the timing from 25 to 20 deg BTDC. At cruise when your former 200HP engine was making 150HP, you can still make 150HP. That is nowhere near the detonation limit even with 94 octane fuel. So the only place it would matter is for takeoff at low elevation airports.
 

And at a higher elevation airport, you could probably use the original 25 deg timing without any detonation issue because of the lower manifold pressure.

Don't forget that it has nothing to do with what we want, it has to do with what they are going to do to us.

[Shadrach]

5 minutes ago, N201MKTurbo said:

Only takeoff and initial climb. With something like a SIM, you could take off with reduced power and in cruse and climb for that matter. 

Take off and climb are the most crucial to safety and usibilty.  Requiring a SIM with a timing map certified to work with a new fuel seems like a bigger regulatory ask than where we are now.

[GeeBee]

Nobody is going to reduce the HP on the data plate of an installed engine on a certified airplane.

 

[EricJ]

46 minutes ago, Shadrach said:

No one here has articulated an actual technical concern with the fuel...

Storage and material compatibility has been mentioned a number of times, and George has said that it may be an issue.

[GeeBee]

3 minutes ago, EricJ said:

Storage and material compatibility has been mentioned a number of times, and George has said that it may be an issue.

He has been flying a Cirrus with it for 14 years. So we know it works in a TIO-550. There was also no effect upon the fuel seal used in Cirrus tanks.  He also had to demonstrate storage and compatibility to the FAA to the extent that he could and no problems. The only way to get more testing is to field it.

[GeeBee]

4 minutes ago, GeeBee said:

He has been flying a Cirrus with it for 14 years. So we know it works in a TIO-550. There was also no effect upon the fuel seal used in Cirrus tanks.  He also had to demonstrate storage and compatibility to the FAA to the extent that he could and no problems. Finally ERAU ran it in a 300 hour test with no problems. The only way to get more testing is to field it.

 

[MikeOH]

1 hour ago, Shadrach said:

Ok then, this begs the question what would be satisfactory? The fuel has 100s if not 1000s of hours of testing on the most sophisticated aviation engine test stand available...anywhere.  It has gone through two STC applications and met all standards for approval each time through two different FSDOs.
No one here has articulated an actual technical concern with the fuel, just concerns about product development as a process in general. Either there is a standard or here isn’t. If there is, either that standard has been met or there hasn’t. In this case there is a standard for STC approval. If one has an issue with said standard or the processin which approval was granted, then make it known.  “I am sure there is something wrong with it because there have been things wrong with other things at other times that I have observed ” is a lousy argument.

What would be satisfactory:

1) Start selling an alternate fuel (G100UL, or something else, preferably both) ALONGSIDE 100LL until there is enough fleet wide experience to vet the alternate in the real world.

2) Meet the ASTM standard.  Or, have Lycoming (and other engine/airframe manufacturers) accept G100UL without any reservation or voiding of their warranty.  As you say, the standard is either met, or it isn't; right now G100UL does NOT meet the ASTM standard.

Oh, and history pretty clearly shows, over and over, how new products are only found to have unknown defects AFTER full scale production and distribution to the market. So, not sure how that is a "lousy argument"??  Ignoring history is a risky practice!

Your apparent position is that George's data (not even multiple INDEPENDENT test data) shows 'no problem' so the conclusion is that it's 'good to go'...and that's somehow a good argument??

You seem to think I don't want G100UL.  Not true.  What I want is an alternate fuel that is field proven BEFORE 100LL is banned.  Having multiple alternates along with 100LL will also avoid predatory pricing during the transition.

[N201MKTurbo]

This document summarizes the state of the unleaded fuel situation pretty well.

https://www.nata.aero/assets/Site_18/files/EAGLE/FactorsAffectingtheCommercialSaleofEmergingUnleadedAviationFuels.pdf

[Will.iam]

On 8/7/2024 at 11:44 AM, MikeOH said:

All I am certain of is that it WILL cost more per gallon.

Initially probably so, but that is mostly because of lack of scale and acceptance. Like when LED TV first came out way more expensive than CRT  TV’s but now today way cheaper. If any petroleum company can blend this G100uL with easier to access ingredients than the monopoly TEL is at one company over in Europe then the price will come down. And if other groups start using it like auto racers as hey it’s got higher octane than anything they could use before then that’s even more demand driving more production then what is out there for 100LL today which again more scale which may bring G100UL dare i speculate cheaper than 100LL especially since with less demand 100LL go the way like R-22 of the past and currently R-134 which is getting hellishly expensive to get now but i digress. 

[EricJ]

57 minutes ago, N201MKTurbo said:

This document summarizes the state of the unleaded fuel situation pretty well.

https://www.nata.aero/assets/Site_18/files/EAGLE/FactorsAffectingtheCommercialSaleofEmergingUnleadedAviationFuels.pdf

That's a good document for further illuminating the issues.

[GeeBee]

2 hours ago, MikeOH said:

What would be satisfactory:

1) Start selling an alternate fuel (G100UL, or something else, preferably both) ALONGSIDE 100LL until there is enough fleet wide experience to vet the alternate in the real world.

2) Meet the ASTM standard.  Or, have Lycoming (and other engine/airframe manufacturers) accept G100UL without any reservation or voiding of their warranty.  As you say, the standard is either met, or it isn't; right now G100UL does NOT meet the ASTM standard.

Oh, and history pretty clearly shows, over and over, how new products are only found to have unknown defects AFTER full scale production and distribution to the market. So, not sure how that is a "lousy argument"??  Ignoring history is a risky practice!

Your apparent position is that George's data (not even multiple INDEPENDENT test data) shows 'no problem' so the conclusion is that it's 'good to go'...and that's somehow a good argument??

You seem to think I don't want G100UL.  Not true.  What I want is an alternate fuel that is field proven BEFORE 100LL is banned.  Having multiple alternates along with 100LL will also avoid predatory pricing during the transition.

Really? Who wants to invest in two dispensing systems? You want to put up the money?

You guys are like the 5 stages of grief.

Denial

Anger

Bargaining

Depression

Acceptance

 

Right now you are bargaining with financially impractical solutions.

 

The only way this gets solved is to put the fuel in the field and see what happens.

[Shadrach]

35 minutes ago, MikeOH said:

What would be satisfactory:

1) Start selling an alternate fuel (G100UL, or something else, preferably both) ALONGSIDE 100LL until there is enough fleet wide experience to vet the alternate in the real world.

2) Meet the ASTM standard.  Or, have Lycoming (and other engine/airframe manufacturers) accept G100UL without any reservation or voiding of their warranty.  As you say, the standard is either met, or it isn't; right now G100UL does NOT meet the ASTM standard.

Oh, and history pretty clearly shows, over and over, how new products are only found to have unknown defects AFTER full scale production and distribution to the market. So, not sure how that is a "lousy argument"??  Ignoring history is a risky practice!

Your apparent position is that George's data (not even multiple INDEPENDENT test data) shows 'no problem' so the conclusion is that it's 'good to go'...and that's somehow a good argument??

You seem to think I don't want G100UL.  Not true.  What I want is an alternate fuel that is field proven BEFORE 100LL is banned.  Having multiple alternates along with 100LL will also avoid predatory pricing during the transition.

You seem to be confusing the term standard and specification. G100UL does not have an ASTM specification. It has met or exceeded the standards for ASTM D910 per memorandum ANE-2010-33.7-5A released by the FAA Engine and Propeller Directorate (EPD) on July 26, 2011, long before PAFI was even a thing. I’m not sure what people think the STC approval and 10+ years of testing and analysis was based on.  G100UL conforms to a specification that that was created during the STC approval process. If you examine the document, you will see a number ASTM test methods/standards specified within the document. G100UL wasn’t subjected to the PAFI framework because it would have required $hit canning three years of R&D and certification work. 
This is purely my speculation and reading of the timeline of events, but it looks to me like Continental, Lycoming and Cirrus were all engaged with GAMI early in the development process but when PAFI came along 3 years later, the politically expedient thing to do was to be team players and jump on board the PAFI bandwagon. GAMI was not the politically expedient product to support. More than 10 years have passed and PAFI has not yet delivered a viable drop in.

One thing is obvious from this thread. There are a lot of uninformed folks regarding the process and approval. Every one is entitled to an opinions no matter how uninformed. 

[BlueSky247]

This thread should be renamed Expired Equine Flagellation.