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-   -   100LL Future and Engine Purchase Concerns (https://vansairforce.net/community/showthread.php?t=163606)

mjanduda 08-28-2018 04:41 PM

Quote:

Originally Posted by rv6ejguy (Post 1284298)
Computer controlled fuel and spark has lots to do with it too. At least we can add those parts to help out the old Lyc these days. We can retard the spark at high MAP to avoid detonation and re-advance when MAP is lower to gain back the power and efficiency. Can't do that with mags.

Back to the first question in this thread:
You think by using modern ignition systems you can use MOGAS on an IO-390 without engine modifications and without losing lots of power or lifetime?

rv6ejguy 08-28-2018 06:54 PM

Quote:

Originally Posted by mjanduda (Post 1284302)
Back to the first question in this thread:
You think by using modern ignition systems you can use MOGAS on an IO-390 without engine modifications and without losing lots of power or lifetime?

Yes. 390s are base timed at 20 degrees already which is conservative. The 8.7 CR is not too high. Once the MAP drops below about 27 inches, you should be able to run the full 20 degrees on 91 octane. You might give up 5-7hp running 18 degrees at SL. No negative impact on engine life.

BMC_Dave 08-29-2018 12:04 AM

Quote:

Originally Posted by rv6ejguy (Post 1284320)
Yes. 390s are base timed at 20 degrees already which is conservative. The 8.7 CR is not too high. Once the MAP drops below about 27 inches, you should be able to run the full 20 degrees on 91 octane. You might give up 5-7hp running 18 degrees at SL. No negative impact on engine life.

How about 87E10 in a IO-540 with 7.2:1? :O

rv6ejguy 08-29-2018 04:09 AM

Quote:

Originally Posted by BMC_Dave (Post 1284365)
How about 87E10 in a IO-540 with 7.2:1? :O

Same thing applies, reduce total timing down to 20ish at sea level MAPs, by 25 inches, I'd think you could be back up to 24-25 degrees total. Would cost you a few ponies at SL vs. 91 octane. You'd have to weigh the cost vs. power de-rating of the two fuels.

F1R 08-29-2018 06:20 AM

Have a look at this
 
Quote:

Originally Posted by BMC_Dave (Post 1284365)
How about 87E10 in a IO-540 with 7.2:1? :O

https://youtu.be/K46IJV0Lg24?t=8s

Here is an STC'd $12,000 water injection system for IO 520 Continentals
If you watch the first 2 minutes you will see the MP and CHT values the system starts flowing at. Mostly at take off power settings with MOGAS

A slightly different tool to address pre ignition / detonation that lets you maintain high MP and normal advance for rated HP output.

jacoby 08-29-2018 08:06 AM

Quote:

Originally Posted by Mudfly (Post 1284297)
This is from the Shell link I listed on post 1. (Avgas Fact and Future).
Is this relative to mjanduda's question? Last paragraph mainly.

"Octane rating is a measure of how resistant a fuel is to detonation or "pinking"; the higher the Octane rating, the more the fuel / air mixture can be compressed without detonation happening. To make this clear, octane rating is not a measure of the amount energy in the fuel, but is a measure of its resistance to detonation.

The advantage or higher octane fuels is that a higher compression ratio or supercharging ratio can be used, which then leads to a higher engine cycle efficiency, which in turn means more power output for a given fuel burn. However, to confuse things further, there are four principal ways to measure Octane rating, RON, MON, Lean Mixture and Rich Mixture ratings.

Road fuels tend to be measured on a RON scale, for which unleaded fuels tend to be 95 - 98 RON but are only 85 - 87 MON. Avgas is measured on Lean Mixture (similar to MON) but also has a Rich Mixture Octane rating.

The Lean Mixture rating is 100 octane (15 octane higher than the comparable 85 MON for unleaded Mogas) but Avgas also has a Rich Mixture rating of 130 which allows higher supercharger boost pressures to be used without detonation occurring. This is particularly a problem when using high power settings at low altitude, for example during take off.

As you can see TEL in Avgas makes a significant difference to the octane rating and without it Octane ratings would be back down to 80 - 85 Lean Mixture - the level for road fuels - instead of 100 / 130. This is not a problem for most typical modern normally aspirated engines as their compression ratios are quite modest and detonation would not be a problem with 80 - 85 Lean Mixture Octane fuel."

1 - "pinking" should be "pinging"
2 - road fuels in the US are rated in AKI not RON. AKI is (RON+MON)/2. You'll see that formula shown on pumps

rv6ejguy 08-29-2018 08:16 AM

Quote:

Originally Posted by jacoby (Post 1284411)
1 - "pinking" should be "pinging"
2 - road fuels in the US are rated in AKI not RON. AKI is (RON+MON)/2. You'll see that formula shown on pumps

Likely from Shell UK where the term used is "pinking" and also where they rate their road fuels differently than North America.

In any case, under 9 to 1 Lycomings can safely use 91 AKI with proper timing adjustments and care with AFRs. Under 7.5 CRs ones can run on 87 AKI with the same care.

The Swift UL avgas is higher octane and certainly suitable as well.

The "universal" UL avgas, when it's introduced, is likely to be similar in octane rating to the current 100LL so as not to have to derate the current turbocharged engines too far, if at all.

jacoby 08-29-2018 08:32 AM

Quote:

Originally Posted by rv6ejguy (Post 1284413)
Likely from Shell UK where the term used is "pinking" and also where they rate their road fuels differently than North America.

In any case, under 9 to 1 Lycomings can safely use 91 AKI with proper timing adjustments and care with AFRs. Under 7.5 CRs ones can run on 87 AKI with the same care.

The Swift UL avgas is higher octane and certainly suitable as well.

The "universal" UL avgas, when it's introduced, is likely to be similar in octane rating to the current 100LL so as not to have to derate the current turbocharged engines too far, if at all.

"pinking" is a new one to me! I thought it was a typo. Shell UK would also explain the use of RON. The link was to shell.com though that could be their international site.

Has anyone tried to use in-tank pumps with EFI? You'd nearly eliminate the vapor lock issues (pretty hard to vapor lock at 2-3 bar), extend pump life, and have automatic redundancy.

BMC_Dave 08-29-2018 09:35 AM

Quote:

Originally Posted by F1R (Post 1284385)
https://youtu.be/K46IJV0Lg24?t=8s

Here is an STC'd $12,000 water injection system for IO 520 Continentals
If you watch the first 2 minutes you will see the MP and CHT values the system starts flowing at. Mostly at take off power settings with MOGAS

A slightly different tool to address pre ignition / detonation that lets you maintain high MP and normal advance for rated HP output.

Huh, that's interesting thanks for the link!

Quote:

Originally Posted by rv6ejguy (Post 1284371)
Same thing applies, reduce total timing down to 20ish at sea level MAPs, by 25 inches, I'd think you could be back up to 24-25 degrees total. Would cost you a few ponies at SL vs. 91 octane. You'd have to weigh the cost vs. power de-rating of the two fuels.

Awesome. With most options away from home being 100LL would one need two configurations or could you run those settings for higher octanes as well?

rv6ejguy 08-29-2018 09:41 AM

Quote:

Originally Posted by jacoby (Post 1284419)
"pinking" is a new one to me! I thought it was a typo. Shell UK would also explain the use of RON. The link was to shell.com though that could be their international site.

Has anyone tried to use in-tank pumps with EFI? You'd nearly eliminate the vapor lock issues (pretty hard to vapor lock at 2-3 bar), extend pump life, and have automatic redundancy.

If an in tank pump fails, you can't access the fuel in that tank. The current pump life is excellent and vapor lock hasn't been an issue if proper location and plumbing practices are followed.

We strongly recommend that people use what's been proven over a half million flight hours with regards to the EFI fuel system if you don't want surprises or to be on a test program to validate a new design.

F1R 08-29-2018 11:03 AM

[quote=BMC_Dave;1284442]Huh, that's interesting thanks for the link!

Here is a much deeper look at the history and some of the early research and aviation user data.
https://youtu.be/1PA70pN6zPM?t=4m8s

A bit long but a lot of good information.

jacoby 08-30-2018 01:36 PM

Quote:

Originally Posted by rv6ejguy (Post 1284444)
If an in tank pump fails, you can't access the fuel in that tank. The current pump life is excellent and vapor lock hasn't been an issue if proper location and plumbing practices are followed.

We strongly recommend that people use what's been proven over a half million flight hours with regards to the EFI fuel system if you don't want surprises or to be on a test program to validate a new design.

You could use a venturi-style cross-draw setup in the event of a pump failure in one wing. This setup has been standard practice in automotive applications that have the fuel tank straddle the driveshaft hump for some 20 years now.

It would make plumbing slightly more difficult and it would be a lot harder to change a pump in the event of a failure but no more difficult than a bad fuel sending unit.

And yeah I get the "don't rock the boat" comment. I was just curious if anyone had tried dual in-tank pumps in an aircraft before.

airguy 08-30-2018 01:57 PM

Quote:

Originally Posted by jacoby (Post 1284716)
And yeah I get the "don't rock the boat" comment. I was just curious if anyone had tried dual in-tank pumps in an aircraft before.

Why? It's not needed. Dual parallel pumps and a simple duplex valve accomplish the same thing with less complexity and cost, and preserve the redundancy of dual pumps.

rv6ejguy 08-30-2018 04:27 PM

Quote:

Originally Posted by jacoby (Post 1284716)
You could use a venturi-style cross-draw setup in the event of a pump failure in one wing. This setup has been standard practice in automotive applications that have the fuel tank straddle the driveshaft hump for some 20 years now.

It would make plumbing slightly more difficult and it would be a lot harder to change a pump in the event of a failure but no more difficult than a bad fuel sending unit.

And yeah I get the "don't rock the boat" comment. I was just curious if anyone had tried dual in-tank pumps in an aircraft before.

I'm not understanding what you're describing here. If you have one pump in each tank and the pump fails, you can't get at the rest of the fuel in that tank.

In aviation, once we have demonstrated the reliability of a layout or system, we repeat that without deviation to get the same results over and over.

If you want to put pumps in the tanks, you could. I've just outlined the main reason it's not done. We have a proven, very reliable layout now with few drawbacks. I'm not sure why it would be a good idea to change that. What would be the advantage over the existing layout?

jacoby 08-30-2018 07:49 PM

Quote:

Originally Posted by rv6ejguy (Post 1284748)
I'm not understanding what you're describing here. If you have one pump in each tank and the pump fails, you can't get at the rest of the fuel in that tank.

In aviation, once we have demonstrated the reliability of a layout or system, we repeat that without deviation to get the same results over and over.

If you want to put pumps in the tanks, you could. I've just outlined the main reason it's not done. We have a proven, very reliable layout now with few drawbacks. I'm not sure why it would be a good idea to change that. What would be the advantage over the existing layout?

You use the velocity of the fuel to create suction to basically create four pumps out of two. In an EFI setup you would put it on the return line since you don't want any air in the event of the other side running out of fuel. When both pumps are running they're cross feeding at the "same" rate (you would probably size the restrictor to be slightly larger on one side so you don't feed fuel out the vent when running on both). If one were to die the other would pick up the slack and cross feed the dead side into the active side.

And I understand the current setup is quite reliable. I am not at all questioning that. However in-tank pumps live a happier/cooler/quieter life and you don't have to worry about vapor pressure at all and the packaging is a bit simpler since most of the bulk lives in the tank. It's more of a question of "has it been done" and "why not if not?".

Here is a random image I found that describes the setup. Just imagine each side of the saddle is a wing:


Mudfly 08-30-2018 08:05 PM

Motive Flow
 
Same as motive flow? Motive flow is used in fuel tanks of most biz jets I'm familiar with.
Here's a basic description I found.

https://aviation.stackexchange.com/q...raulic-systems

jacoby 08-30-2018 08:21 PM

Quote:

Originally Posted by Mudfly (Post 1284798)
Same as motive flow? Motive flow is used in fuel tanks of most biz jets I'm familiar with.
Here's a basic description I found.

https://aviation.stackexchange.com/q...raulic-systems

Yes. You'd use the motive flow to move fuel from the dead tank to the active tank in the event of a pump failure. In a dual-pump situation both pumps would be moving fuel equally and would cancel each other out (or you would have pressure valves that prevent the cross-flow in equilibrium).

rv6ejguy 08-31-2018 04:54 AM

Quote:

Originally Posted by jacoby (Post 1284803)
Yes. You'd use the motive flow to move fuel from the dead tank to the active tank in the event of a pump failure. In a dual-pump situation both pumps would be moving fuel equally and would cancel each other out (or you would have pressure valves that prevent the cross-flow in equilibrium).

I'm familiar with the widespread use of jet pumps in jet aircraft. With the present system, we usually run on one pump at a time and there are less components and plumbing so less weight and complexity.

This being experimental aviation, nothing is stopping you from implementing your ideas on your aircraft if you see some advantages there.

I just don't see any advantages with this layout.

RV6_flyer 08-31-2018 05:50 AM

SHELL?S FUEL UNDER STUDY
 
Most recent AOPA article on 100LL replacement. EAA had a similar article.

Mudfly 08-31-2018 06:26 AM

Quote:

Originally Posted by RV10inOz (Post 1284147)
Do not stress.

The PAFI process was fatally flawed right from the beginning. Recently proven.

There is a certification project almost complete and has taken time due funding and apathy of the market to get behind it, but is literally "months" or "weeks" from a major milestone.

G100UL is the likely fuel you will have when the time comes. So relax. Build on.

Quote:

Originally Posted by RV6_flyer (Post 1284844)
Most recent AOPA article on 100LL replacement. EAA had a similar article.

Thanks Gary. Interesting info. Sounds like discussion @ 5 min mark on
AOPA video https://www.aopa.org/news-and-media/...n=180830epilot could be related to what RV10inOz brought up in his post.

rv6ejguy 08-31-2018 06:45 AM

Will be interesting to see how this all shakes out. Shell has the size/ funding and existing network to make this happen more quickly IMO than the other players but hopefully Swift and GAMI will also be in here as alternative competition.

robertahegy 09-01-2018 09:46 AM

Interesting this debate is still going on. Fifteen years ago when I was making the decision on the engine and fuel system for my 7A everyone was worried then that 100LL was on it's way out. If there is a large enough market, someone will continue to produce it, or a reasonable substitute.

Roberta

RV10inOz 09-01-2018 07:39 PM

Shell developed a really cool new paint stripper. SWIFT won't start in Winter or if you brew it synthetically the components cost north of $12/gal before you get started. And it didn't work (not when my data source was current).

Neither is fungible with the existing avgas. At some point you need to have a changeover period and a long and lengthy one at that.

One fuel does tick all the boxes and does better in some areas than current 100LL., and it was never part of the fatal flawed PAFI project. Make of that what you will. And just because one company is huge and has large cash sources does not mean that they can or will solve the problem. They haven't.

rv6ejguy 09-01-2018 08:00 PM

Quote:

Originally Posted by RV10inOz (Post 1285238)
Shell developed a really cool new paint stripper. SWIFT won't start in Winter or if you brew it synthetically the components cost north of $12/gal before you get started. And it didn't work (not when my data source was current).

Neither is fungible with the existing avgas. At some point you need to have a changeover period and a long and lengthy one at that.

One fuel does tick all the boxes and does better in some areas than current 100LL., and it was never part of the fatal flawed PAFI project. Make of that what you will. And just because one company is huge and has large cash sources does not mean that they can or will solve the problem. They haven't.

It will be a tough haul for any company without the size and financial/ refining/ distribution resources to do this no matter how good their formulation might be. That's a hard reality unless they sell the rights to someone like Shell- if Shell would buy.

It's one thing to come up with a recipe that ticks all the boxes, quite another to get this in world wide or at least country wide distribution.

There is at least one other US player developing UL avgas outside of PAFI, who few people know about. I was just talking to someone in that company last week and they have a very good formulation it sounds like.

ColoRv 09-01-2018 08:51 PM

Ahhh memories. There once was a time when this website didn?t exist. RV builders communicated via an email list where we either received one email containing all of the emails for the day or hundreds of emails spaced apart by seconds. It was great. Back when that list was an infant was the first time I heard someone say with certainty that Low Lead was going away shortly and we were all doomed.

I am still waiting....but I did finally stop holding my breath. So, until Hades freezes over and the seas of Low Lead dry up....I?ll keep destroying the environment with buckets of lead, bragging about my carbon footprint and whacking every baby seal I see on the head with a hammer.

az_gila 09-01-2018 10:52 PM

Quote:

Originally Posted by RV8JD (Post 1285234)
Yes, but the difference now is that there is a growing number of mostly non-aviation folks who want all the lead out of all gasoline due to environmental concerns, and have sued to accomplish that goal.

Yes... there are rumblings in the UK about Innospec on the River Mersey -



Which is the only supplier of TEL - tetra ethyl lead, the lead bit of 100LL - in the free world.

https://www.petro-online.com/news/me...ol-legal/43931

Every time I go to Liverpool I look across the river to see that the plant is still there :) It was still there a year ago.

grubbat 09-02-2018 05:55 AM

Lead free
 
Lead free racing fuel has been around for a while at Sunoco. Granted it?s high cost, but if I recall, it was something like 110 octane. If the stuff would work in AC, then I wonder what the cost would be if the supply chain was a larger?

F1R 09-02-2018 08:59 AM

130 Octane
 
Does anybody have the accurate records for the make up of 130 Octane gasoline that was used in the 1940's when Mustangs, Spits and other merlin powered AC used it?

Mudfly 10-09-2018 07:09 AM

100LL Update
 
Latest update (Sep 7, 2018) on the Piston Aviation Fuels Initiative (PAFI) from the FAA website.

FWIW: "...PAFI flight testing and some engine testing was halted, resulting in a delay in testing completion ? from December 2018 to mid-2020."

https://www.faa.gov/about/initiatives/avgas/

I'll continue to check the website daily for further updates :) .

RV7A Flyer 10-09-2018 10:35 AM

Quote:

Originally Posted by F1R (Post 1285327)
Does anybody have the accurate records for the make up of 130 Octane gasoline that was used in the 1940's when Mustangs, Spits and other merlin powered AC used it?

Isn't it *still* used by the air racers?

az_gila 10-09-2018 11:09 AM

Quote:

Originally Posted by F1R (Post 1285327)
Does anybody have the accurate records for the make up of 130 Octane gasoline that was used in the 1940's when Mustangs, Spits and other merlin powered AC used it?

Here is the spec for the 150 octane stuff -

http://www.wwiiaircraftperformance.o...grade-spec.pdf

And lots of history on the introduction of 150 to replace/supplenet 130 octane fuel in WWII

Lots of links in the footnotes -

http://www.wwiiaircraftperformance.o...rade-fuel.html

rv6ejguy 10-09-2018 01:52 PM

Quote:

Originally Posted by RV7A Flyer (Post 1294237)
Isn't it *still* used by the air racers?

Many of the fast guys are running auto race fuel which is higher octane and oxygenated as well.

RV10inOz 10-10-2018 03:29 AM

Just a slip of the keyboard.......... when G100UL gets out there (soon) it will perform like the old purple gas and I have seen the test reports from Dixie Labs.

Lots of good things..........but geez it takes time........

Mudfly 08-13-2019 07:00 AM

Sorry, I apologize ahead of time for this post, but I only get on this soapbox once a year.
For those interested, here's an update (June 20, 2019) on the PAFI program from the FAAs website. https://www.faa.gov/about/initiatives/avgas/
I attended the PAFI forum at OSH this year hosted by reps from EAA, AOPA, and FAA. Unfortunately, no announcement of any breakthrough was discussed. According to the panel members, tetraethyllead (TEL) was the "magic bullet" in the 1920s and it remains so today. They stated there is no simple fix and were actively inviting new participants with ideas to join the program. A question was asked by someone in the audience as to why eliminating AVGAS was such a big deal since, "in the big picture", it produces such a small amount of lead emissions. The panel agreed that is is a very small amount of lead however, "it's a done deal". Suits filed from environmental groups beginning in 2006 are still on the books, and while no action has been taken since around 2012, the fact remains. The panel mentioned several times "we are committed to removing lead from AVGAS". They are probably required to make that statement not knowing who is in the audience.
All that said, AVGAS probably not going away anytime soon, I understand that. However, I do find it interesting that engine manufacturers continue to build, and more importantly we continue to BUY, engines that require a fuel the FAA, EPA, and other agencies continue to state they are committed to eliminate. I wonder if a better path for the last several years may have been spending time and money (I think $35 million was the amount congress gave the PAFI program), in researching and developing engine solutions rather than a replacement fuel. During that time, airplanes would have continued to burn 100LL, and as TBO's and service life of these engines were reached it may have been possible to replace with an updated engine that doesn't require AVGAS. My vote would be for a JET A because of world-wide availability, ease of refinement and distribution, and only one pump required at the airport. Don't get me wrong here. I don't want AVGAS to go away anytime soon, I sure enjoy flying my buddies RV10 when I get the chance. However, I want a long term solution so future generations can have the opportunity to enjoy flying small airplanes like we have. I'm just not convinced a replacement fuel is the answer.

rv6ejguy 08-13-2019 07:44 AM

Several big companies continue to work on a 100LL replacement both within and outside PAFI. It takes a long time to gather test data which will satisfy the FAA. Some have not submitted anything to the FAA yet while the formulations undergo independent testing.

It will have to have similar density and other characteristics to be approved. Not so easy as it seems.

No way new engines will replace what's in the fleet now, any time soon. Not practical on so many levels, both technical and economic.

Mudfly 01-28-2020 10:19 AM

For those interested, here's the latest update from the FAA on the 100LL replacement program (PAFI).

https://www.faa.gov/news/fact_sheets...m?newsId=14754

airguy 01-28-2020 12:31 PM

Quote:

Originally Posted by Mudfly (Post 1403794)
For those interested, here's the latest update from the FAA on the 100LL replacement program (PAFI).

https://www.faa.gov/news/fact_sheets...m?newsId=14754

Looks like the program is in high-speed neutral, just as expected.

Capt 01-29-2020 02:31 AM

I don't believe we have to worry about LL fuel not being avail for quite a long time yet! The issue might be cost in the future, availability is the least of our worries. So fly fly fly:D

Sue 01-29-2020 03:59 PM

Fuel
 
Maybe some of our colonial brothers from accross
the pond would chime in here. A few years ago in
Great Britain they allowed you to burn ?auto fuel ?
in several types of aircraft. One of the restrictions
was not flying above ?4000 ft. Run down to your
neighbor hood gas station fuel up and take off in
the summer months then climb up to cool off and
you would be surprised how many people encounter
ruff running engine problems that are probably the
onset of vapor lock problems.

airguy 01-30-2020 07:19 AM

Quote:

Originally Posted by Sue (Post 1404114)
Maybe some of our colonial brothers from accross
the pond would chime in here. A few years ago in
Great Britain they allowed you to burn ?auto fuel ?
in several types of aircraft. One of the restrictions
was not flying above ?4000 ft. Run down to your
neighbor hood gas station fuel up and take off in
the summer months then climb up to cool off and
you would be surprised how many people encounter
ruff running engine problems that are probably the
onset of vapor lock problems.

It can certainly be done, but not as simply as some folks would think. I've been operating almost 600 hours now on 91 premium autofuel (with ethanol) at altitudes in the mid-teens quite regularly, and I've been to FL210 with it once just to see what would happen, all was good. But to be fair - I did make some mods to my fuel system to allow me to do that, it's a little more complicated than just "run down to the neighborhood gas station".


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