The future of 100LL and Warbirds?

[shrike]

I knew the time I spent in college researching and learning about chemistry and materials was a waste of time. I bow out of this thread...

Rather than rolling your eyes, you could use that time spent in college to good effect and point out the error of my ways.
My observations are based on years of empirical evidence - about 1000 Lycoming and TCM cylinders through our shop each year- and many years keeping antique high perfomance engines happy and functional.

[famvburg]

Ms. has a state tax on 100LL as well as Jet. IIRC, certain businesses can get it back, but it is just a fuel tax. ISTR about 20 or so years ago there was some scuttlebutt about applying road tax to aviation fuels because the tankers that delivered it used the roads, completely disregarding the fact that they were already paying road taxes.

[Enemy Ace]

Red tail,
I would ask that you be a little less sensitive and continue to contribute. I found your posts very educational. I don't have any background in chemistry that is not tequila or Rum based. Just because one person posts something that you may find contradictory doesn't mean that dozens of lurkers reading the thread aren't learning from you.
I own several airplanes with engines that are going to be effected by the fuels change, this is an important topic and I want to learn all I can. Having enough problems with the alcohol in fuels now both in cars and planes. Heck even the old farmall tractor isn't very happy with what it's being fed these days.

[JDK]

A slight tangent, inspired by bdk's wondering about possible reasons behind the wind-down of TEL fuels.

Introducing Thomas Midgely Jr, probably the most poisonous person on the planet, ever. I did a little article on my blog, a while ago which touched on him and the lies told on TEL.

http://vintageaeroplanewriter.blogspot. ... ually.html

Enjoy.

[shrike]

I am not going to apologize for statements based on my observations and experience.
That said, I'm perfectly willing to accept any reasoned refutation of my points, but have no patience for the 'I'm taking my ball and going home' school of argument.

[Mark Allen M]

Señor Red Tail and Señor Shrike I hope you can put aside whatever is causing the rift and continue this conversation. There's some good stuff in this thread being posted by both of you that has been quite interesting.

What's that darn line Spock said in one of those old Star Trek movies?

"The needs of the many ... Out weight the needs of the few"?

So come on now fellas, one of your students is sitting here waiting to learn more

[51fixer]

Both Roush and Allison Competition Engines make seats and valve train parts out of better materials to be able to handle the lack of fuel additives.
Not all the engines used today feature this change and many of the small or more rare engines won't have this as a possibility.
If the big time engine guys recognize an issue then I'm not so sure it can be dismissed.
Back in the 80s when the LL formulations were introduced some engines didn't like it and fuel flows were changed.
I remember changing several heads and banks on Allison's back then. I did both engines on a P-38 twice in a couple years.
Plug and Play of this fuel will probably require tweaking once again on some of the Warbirds.

[Red Tail]

I’m not asking for any apology nor do I think one is required. I didn’t care for the demeanor of the response. Maybe it was just Shrikes delivery or my interpretation of it that set me off. Some of what he wrote I agree with, some not so much, some I will leave for another time if at all.

Understand I am not a proponent of Tetraethyl lead in fuel because of the deposits it leaves throughout the combustion chamber and the litany of issues that causes as well as its corrosive nature…to say nothing of its environmental hazards. There is little if anything good to say about it. BTW, there is only one plant still producing it. It’s located in the UK…Google will provide the name of it if interested.

Any viable valve seat insert will be harder than the surrounding aluminum head casting so that’s a relative term and a point that can’t be argued. While valve seat inserts are commonplace in alloy heads, for the most part the term “Hardened” valve seats came from the auto industry back in the late 1960’s and early 1970’s when most production engines used cast iron heads. Few, if any of those heads contained inserts, or had induction hardened seat areas or flame hardened seat areas. When the TEL was removed from the fuel, valve recession quickly occurred in applications where high specific power output and high loading caused elevated valve and valve seat temperatures. This is starting to sound eerily a like the operating envelope of high performance military aviation piston engines. When the valve and seat come together (With considerable force), small bits of the valve seat weld to or transfer onto the valve head. When the valve opens the welded/transferred seat material pulls off the seat and hot exhaust gasses oxidize it off the valve head and send it out with the spent gasses. The TEL in fuel acts as a barrier between the valve head and seat and effectively stops the material transfer between the two surfaces.

The answer was to harden the valve seats or install valve seats that would tolerate the new “Dry” unleaded fuel. This included many aluminum heads that were originally designed and built with inserts (They used inserts because aluminum would quickly fail as a valve seat material). In the aviation community some OEM inserts installed prior to the 1970’s were also found to be intolerant to unleaded fuel. Again, not all engines are going to turn into pumpkins because the fuel will no longer have TEL in it. Some of the high specific power engines were built with materials tolerant to an unleaded environment almost by accident because they needed to survive the increased heat loading placed on them. As mentioned before, the Merlin is one of them.

The coefficient of expansion (CE) of a seat insert will never match that of the cast aluminum alloy head provided it’s made from a different material than the head itself (Which is the objective, right?). No one material will have an equivalent CE as that of another (Material science). The CE of most aluminum alloys is around 13 (microinch/(in oF)) whereas those materials suitable for the insert materials are generally in the 5.5 to 9.5 range. This is why the inserts are threaded and installed in the head with an interference fit. (The insert is chilled with LOX [liquid oxygen] or LN2 [liquid nitrogen] to shrink it and the head heated to expand it. This allows for enough clearance and time to thread the insert in before the aluminum casting contracts holding the insert in place). The interference fit is designed to be tight enough to hold and seal the insert into the head throughout its typical range of operating temperatures. Over time even the inserts will begin to bypass gasses between it and the head casting and leads to serious issues.

The detonation limits of 100LL has way more variables than just compression and ignition advance. I’ll leave it at that.

Regards,
John

[Mark Allen M]

I didn’t care for the demeanor of the response.

John let me give you some friendly advice (this coming from a multiple banned knucklehead as myself) I'd say IMHO that 50% of what is written by others can, and at times does, come across as something it wasn't mean't to be. Trust me I learned the hard way to take a step back, re-group and then post. It works for me sometimes and it flames me sometimes. It's just the nature of these kooky website forums. Shrike is a good dude and has a wealth of knowledge, as do you, and you both have taught me a thing or two I didn't know, and wanted to know. Thanks much and keep it up.

Another fascinating thread

[CAPFlyer]

I know not much has been made of it, but from the warbird side, Swiftfuel at least looks to be a fully compatible fuel with the radials. It's been 2 or 3 years now since the test was done, but Andersen did a bunch of tests, including a 100 hour run on an R2800 with Swift and found no negative wear or other problems and actually found they were able to run the engine at the original 100/130 and 115/145 power settings without any indication of knock or high CHT. I hope Shell and GAM do similar long-period testing in warbird powerplants becuase I think we'll be surprised at how well they work if given the chance.

[RacingMustang]

Thanks for the answers everyone. I had assumed that those creating a "drop-in" replacement were only considering standard GA planes and not the older high-power engines.

[CAPFlyer]

While they are certainly looking at GA as a primary user, to ignore the radial community (and thus the warbird community) would be to ignore a still substantial portion of the use of AvGas. I haven't seen a recent census, but last I saw a couple years ago, there were still well over 100 radial-powered airplanes in commercial service, not including the Fire Bombers (but including the single engined airplanes like the DHC-2 and DHC-3). Add to that the several hundred warbirds, many of which have more than 1 engine, that's a significant number of engines and users. To not do your best to sell your product to this community would be stupid because they absolutely have sway in the overall industry. If you can give the commercial operators a fuel that allows them to fly more efficiently and improve maintenance, then you're going to potentially keep them from switching to turbine-powered aircraft, meaning you make more money. That's a big driver to get that fuel to as many users of AvGas as possible.

[famvburg]

IIRC, R-985s and R-1340s are 80/87 octane engines (like on Beavers, Otters and a host of cropdusters and warbirds) so whatever comes out to replace 100LL shouldn't be an issue for those smaller radials. Is there some reason that the drop-in replacement for 100LL won't work in an R-2800 or R-3350 already running on 100LL? Also, IIRC, most of the later R-3350s, like in Skyraiders and Neptunes and maybe the late R-2800s were running 115/145 until it was phased out and they then switched to 100/130 and then 100LL today, so if there is a drop-in replacement for 100LL, why can't these engines operate off of it as well is little Lycomings and Continentals?

[shrike]

IIRC, R-985s and R-1340s are 80/87 octane engines (like on Beavers, Otters and a host of cropdusters and warbirds) so whatever comes out to replace 100LL shouldn't be an issue for those smaller radials. Is there some reason that the drop-in replacement for 100LL won't work in an R-2800 or R-3350 already running on 100LL? Also, IIRC, most of the later R-3350s, like in Skyraiders and Neptunes and maybe the late R-2800s were running 115/145 until it was phased out and they then switched to 100/130 and then 100LL today, so if there is a drop-in replacement for 100LL, why can't these engines operate off of it as well is little Lycomings and Continentals?

That's it exactly. I don't believe that there are any real technical hurdles involved, just regulatory ones. And the resistance of people to accept change, even when it can be shown that "but it's always been like that", wasn't always like that at all.

[bdk]

Lead exposure affects the intelligence quotient (IQ) such that a blood lead level of 30 μg/dL is associated with a 6.9-point reduction of IQ, with most reduction (3.9 points) occurring below 10 μg/dL. http://en.wikipedia.org/wiki/Tetraethyllead#Toxicity

I always thought you had to be a dunce to hang around a general aviation airport, now it turns out that I'm a dunce precisely BECAUSE I hang out at the airport. I had it backwards all along!

A slight tangent, inspired by bdk's wondering about possible reasons behind the wind-down of TEL fuels.

Introducing Thomas Midgely Jr, probably the most poisonous person on the planet, ever. I did a little article on my blog, a while ago which touched on him and the lies told on TEL.

http://vintageaeroplanewriter.blogspot. ... ually.html

Enjoy.

Lead is a toxic metal that accumulates in the body and is associated with subtle and insidious neurotoxic effects especially at low exposure levels, such as low IQ and antisocial behavior.[24][25][26] It has particularly harmful effects on children. These concerns eventually led to the ban on TEL in automobile gasoline in many countries. Some neurologists have speculated that the lead phaseout may have caused average IQ levels to rise by several points in the US (by reducing cumulative brain damage throughout the population, especially in the young). For the entire US population, during and after the TEL phaseout, the mean blood lead level dropped from 16 μg/dL in 1976 to only 3 μg/dL in 1991.[27] The US Centers for Disease Control considered blood lead levels "elevated" when they were above 10 μg/dL.

Is this all attributed to the use of lead in gasoline? How about the lead used in paint, and apparently recently still found in paints applied to toys manufactured in China?