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91UL / UL91 / 96UL / UL96 / UL98 / mogas etc (merged thread)

Those figures are surprising to say the least… maybe worldwide if at all, source?

This is the figure mentioned, for worldwide, many times over the years. I have zero doubt that it does not represent Europe, but European GA is around 1/10 to 1/5 of US GA. Numbers can be found here. And then there is the rest of the world (GA is pretty big in Africa for example – take a look at the AIR BP booklet) so Europe is even smaller.

The reality is that US is full of planes which are either turbo or 9:1 CR or higher. Lots of SR22s, all of which need 100LL. Lots of twins; MEPs in Europe died over past 20 years (except small numbers of DA42s) as long term owners got out of GA. Europe is different; I never disputed that. Not just a different makeup of the engine types but also a lot of low time engines, hangar queens, and very low time mission profiles in some aeroclub communities. The US is full of owners who go places. We have to accept reality of business which is that US is what drives the market. If somebody here thinks Europe is more important than the US, they need to ask who builds and certifies most of the engines! And the restrictive practices in European noncertified flight and long term parking privileges mean that the number of people who can fly say an RV is always going to be limited.

“100UL” will be driven (or not) from the US. If it happens there, it will happen here too, soon afterwards. And it will take over from 100LL and dominate the GA airport scene just like 100LL does today. Other fuels will carry on in small markets, just like they do today. Some of them due to a self-contained pilot community where one oil company dominates, some in a country where there is a high acceptance of high taxation in return for reducing or eliminating lead, some in areas where there is a lot of particular type engines, etc.

That’s only one page out of six. But yes, no turbo models.

I was not quoting any document. I have this from US engine shops, as to what runs off 91UL. 9:1 is the max CR they accept as long term reliable (no detonation) and even 9:1 is buildable only for Experimental engines. 9.5:1 will not run on 91UL.

Shoreham EGKA, United Kingdom

What’s important in the general picture, and in the future, is this.

TEL works today because the amount used is insignificant, and it largely goes under the radar politically (no 18 year old environmentalist has any clue what TEL is). The only thing that will happen if we put pressure on 100UL (of some sort), for “environmental reasons”, is politicians will say “What? no reduction in CO2? 100% fossil fuel?That’s not environmental friendly – at all”. The thing is, they are 100% right. Then if you start explaining stuff, you also will have to explain what the TEL substitute is and does regarding the environment. You also have to come up with some statistics, data and numbers, for the actual usage. How many persons need TEL in Europe today? And what for?

The whole thing is just weird. Nobody sees TEL as a problem today. No politicians, not the public, not even the aviation authorities (both the FAA and EASA are more like “Oh please, why must you keep on whining about this”). But for some strange reason it is seen as a problem for pilots, while the real problem, CO2 emissions isn’t.

In the mean time, Diamond, one of the most successful GA manufacturers today has a whole fleet of aircraft that can use any SAF that the industry can cook up. Rotax, the most selling aviation piston engine manufacturer today, can use fuel up to 10% alcohol (SAF in practice), and none of them needs TEL whatsoever. And if that’s not enough, unleaded AVGAS exists, it’s readily available, and can be uses for 90% of piston powered GA (excluding diesel engines).

For most cases this G100UL is a solution to a problem that exists exclusively between the ears of a few pilots. Rather funny. If and when it becomes available, then we will see what it costs. How is this going to work anyway. Will this fuel be imported from the US? How much is that going to cost? It’s patented. Will BP, Total and Shell just sit still and let Gami take over the world? All it takes is a phone call from Shell to some hot shot in EU telling they have this new aviation fuel that will reduce CO2 emissions by 20%, because they have, it’s used in gasoline. Then we will start having fuel problems.

The elephant is the circulation

From here

boscomantico wrote:

Montélimar LFLQ is now 91UL only

Castelnaudary (LFMW) stopped selling Avgas 100LL only Avgas 91UL and Mogas (from car pump with ethanol) two months ago

We end up at Albi (LFCI) that has self-service Avgas 100LL, I think @UdoR got his fuel there as well?

I recall it was 70kts winds, one end up getting Avgas half-way
Even when aircrafts have +1000nm ranges….

Last Edited by Ibra at 12 Jun 11:36
Paris/Essex, France/UK, United Kingdom

boscomantico wrote:

You are mixing up RON and MON.

I am not, I was just not expecting to find out that the 91 in UL91 does not stand for RON (in almost all other fuels, the number stands for RON and not MON).

SP95 is 95 RON, same for SP98. UL91 is apparently 96 RON but you have to go to the ASTM D7547 specification to know that (it’s not written anywhere on Total website).

It’s good to know, but I don’t know if prices are different (see Total prices, don’t know if they are accurate).

Last Edited by maxbc at 12 Jun 11:56

maxbc wrote:

UL91 is apparently 96 RON

And Hjelmco 91/96UL is – despite its name – 98 RON. (It is certified on Hjelmco’s web site.) This difference can matter, e.g. with high powered Rotax engines.

ESKC (Uppsala/Sundbro), Sweden

maxbc wrote:

I am not, I was just not expecting to find out that the 91 in UL91 does not stand for RON (in almost all other fuels, the number stands for RON and not MON).

MON is used in aviation fuels while RON is used for road fuels (US uses AKI = 0.5(RON+MON)), there are few tables to convert between these. On the confusion, don’t worry even the head of engineering at Bristell does not know difference between MON vs RON: they recommend SP98 as it has more than 95 octane unlike UL91, what a joke !

Last Edited by Ibra at 12 Jun 12:50
Paris/Essex, France/UK, United Kingdom

I was just not expecting to find out that the 91 in UL91 does not stand for RON (in almost all other fuels, the number stands for RON and not MON)

That is true mainly for automotive gasoline in Europe, where they picked the biggest number they could for marketing reasons. On a technical level the other test protocols do matter in relation to the operation of an engine and that’s why RON is not used in isolation. Automotive gasoline in the US is sold based on the the average of MON and RON, which is termed pump octane, and this is similar to the rating system for Avgas.

Last Edited by Silvaire at 12 Jun 13:25

Silvaire wrote:

That is true mainly for automotive gasoline in Europe, where they picked the biggest number they could for marketing reasons

RON is the only meaningful number for a car. Besides, historically leaded “super” (or whatever it was called other places) was 100 octane (RON). Easy to remember and relate to: 100% good fuel and every car could use it and run just fine. The lower quality was 95 or 97 (don’t remember), but still leaded. Then came unleaded 95 (or 97?), and finally leaded gasoline was phased out replaced with 98 octane. I think also 99 octane existed for some time, along with several other numbers. It’s only in later years that 98 and 95 have become the standard.

The elephant is the circulation

RON is the only meaningful number for a car.

The motor octane (MON) test was invented (oddly enough) to provide additional data applicable for use in motor engines that was not supplied by use of the research octane test.

The Wikipedia page is here link and explains as follows: “MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel’s knock resistance”

AKI or pump octane is mandated for use in North America for a reason, in relation to selling fuel from the pump for use in cars.

Last Edited by Silvaire at 12 Jun 20:05

Silvaire, time and again, you bring threads off rails here by posting US-specific stuff which, while possibly interesting in general, has no place in the context of the thread. The context was fuels at European airfields, and the fact that the US uses AKI for road fuels is simply not relevant.

Mainz (EDFZ) & Egelsbach (EDFE), Germany
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