Jet A1 in a 100LL engine?

[AdamFrisch]

Bare with me here.

It used to be the case in Scandinavia in the 60's and early 70's that Kerosene (which is Jet A1, for all intents and purposes) was cheaper than gas. So, a lot of manufacturers and retrofitters did a cheeky conversion of sort (a bit like the LPG people do today). They had the car start on gas, then once the temp had come up they switched over to Kerosene form another tank. Apparently worked really well, but did lose some slight power.

How this was achieved I'm not entirely sure, but I think the exhaust was piped around the Kerosene inlet to warm it up and vaporize it, so it could ignite easier.

Now, in these times of imminent banning of 100LL and death and doom for petrol pistons, and if this worked for old car engines, couldn't it be made to work for piston powered aircraft engines?

[Maoraigh1]

Gas oil engines started on petrol, then when hot went over to gas oil. They were fitted to boats and tractors, before pure diesel engines replaced them. They were heavy for their power. Needed two fuel tanks. They were certainly used in the U.K.

[bingofuel]

I think you are refering to tractor vapourising oil (TVO) a blend of petrol and heating oil which was used in petrol engines once the engine was hot enough.

[B2N2]

For all intents and purposes Jet A is (virtually) the same as Diesel.
Avgas is virtually the same as high octane pump gas.
So no, you can't burn only Diesel in a petrol engine or the other way around.
You can run small amounts of contaminated fuel as in about 15-20% petrol in a diesel engine and vice versa.
Turbo prop and jet engines can pretty much run on anything that is combustible but it wouldn't be certified to do so and therefore un-airworthy.
The Russians used to be famous for having airplane engine that could run on the same shabby fuel as their tanks.
Great example is the Sukhoi 25 "FrogFoot".

In short, no you cannot run Diesel or Jet A in a airplane "petrol" engine

[IO540]

I don't think an avgas engine would even run, never mind start, on avtur or diesel.

BTW I don't believe any imminent demise of avgas. There are tens of thousands of avgas planes around the world. About 1/3 of avgas burnt is burnt in engines which cannot run 96UL or similar. Some very good replacement fuel will need to be worked out, and probably retrofit fadec / electronic ignition systems will come in too, for some engines.

You can probably run an avgas engine on a mixture with maybe (at a wild guess) 10% of avtur because the stuff is bound to be soluble in avgas...??

[Staggering]

As I understand it JetA1, diesel & paraffin are pretty much the same stuff & I know that a hot petrol engine will run on paraffin. Many years ago before 24hr opening a friend used to buy paraffin from a forecourt dispenser and run his Landrover on it when he couldn't get petrol. I have done the same with a lawnmower. The engine will only start if it is hot enough to vapourise the fuel. The Landy used to smell like a jet when it went by!!! I am not suggesting you try this in your aircraft!!

[S-Works]

Turbo prop and jet engines can pretty much run on anything that is combustible but it wouldn't be certified to do so and therefore un-airworthy.

Our Walther engines are cleared to run on pretty much anything that burns. If running on Avgas they are specified to be inspected more frequently!!

I would not want to foot the bill for running Avgas through them though at our flow rates!!

[Pilot DAR]

Turbo prop and jet engines can pretty much run on anything that is combustible but it wouldn't be certified to do so and therefore un-airworthy

A number of turbines I have flown do list gasoline or diesel fuel as legal alternatives, though with conditions of cleanliness, and for short and recorded durations between overhaul intervals.

BTW I don't believe any imminent demise of avgas. There are tens of thousands of avgas planes around the world. About 1/3 of avgas burnt is burnt in engines which cannot run 96UL or similar

I know it does sound implausible that 100LL would disappear, but back in the mid 1990's I attended the American Society for Testing and Materials (ASTM) meetings for a number of years. This is the forum at which the standards of these fuels (for North America anyway) are discussed. At those meetings, the US Environmental Protection Agency (EPA) repeatedly presented that the industry have a decade to come up with an approvable alternative. If that did not happen, 100LL would just be banned entirely.

It seems to me that we're about 50% beyond that deadline now, with only modest progress. The 2015 end date I have read about, would represent a doubling of the EPA offer. Considering how serious they seemed about this in the mid 1990's, I would not be surprized if they just banned 100LL, and said "We told you so". 100LL burners represent such a tiny fraction of the gasoline users, they do not speak with a loud enough voice to overcome the "get the lead out" movement.

I envision a big rush for replacement aviation gasoline approval in the next few years...

[Ultranomad]

In fact, unleaded avgas with an octane rating of 100 or more is not too difficult to make. Technical-grade xylene (or an unseparated mix of toluene and xylenes) would have an octane number in the 100-110 range and may even be slightly cheaper than 100LL. Unfortunately, it has a much higher inhalation toxicity and is more aggressive to elastomers than regular avgas, but this isn't an unsurmountable problem.

[AdamFrisch]

Although I would be very saddened by all the aircraft that will get grounded by a 100LL ban, I do welcome the fact that if nothing else, it will pull the aircraft industry kicking and screaming into the modern world.

It's nuts that they haven't come up with engines that can run on unleaded or explored diesels. The Germans managed to certify not only one, but two diesel engines in a couple of years (the Austro in record time) and Continental and Lycoming are still scratching their a**es? Continental has now bought a french diesel, so let's see where that goes...

[JOE-FBS]

There is a long detailed item about the impending demise of 100LL and what can be done as alternatives in this month's AOPA UK magazine (we're all AOPA members here surely?). I don't have it with me but IIRC it's potentially less than ten years away that the US will ban it and some chap in Sweden makes a suitable subsitute but it doesn't get used outside Sweden becuase our free-market loving American cousins would stamp all over him if he tried. Of course, that may all be propaganda.

Oh, and with ten years reprocating engine design behind me, I echo the comments that putting gasoline in your compression ignition reciprocating engine or diesel (jet fuel) in your spark ignition reciprocating engine is a very bad idea indeed, whether it's an automotive or aviation application. I wouldn't think gasoline would do much good in your turbine engine either but I don't have the expertise to be sure.

Well said Adam. It's ridiculous that Cessna and Piper build new aeroplanes with electronic instrument panels, airbag seat-belts, etc. then fit the same 1950s technology engines.

[S-Works]

I wouldn't think gasoline would do much good in your turbine engine either but I don't have the expertise to be sure.

It's OK, put your mind at rest, many turbines are cleared for multi fuel use. Our Walthers are specifically cleared for it in the engine manual along with the inspection requirements.

[mad_jock]

You should see what they burn in oil industry turbines for power generation.

If its hydrocarbon and they can some how get it through an injector noozle they will burn it.

[bingofuel]

Turbines have even been run on coal dust, mind you might need a stoker on board to keep the aircraft in the air!!

[MichaelJP59]

Often said that Jet A1 and diesel are the same stuff - why do they smell so different, is it just additives?

[mad_jock]

I think if you routing around using seach you can find a petrolum engineers description about the technical differences.

Basicaly from what I remember it start's by coming out of the same tap.

Then one lot gets a load of paper work started on it and batched up and the other goes off down a pipe.

Then they start adding things to it.

Presume the difference in smell's is just the different esters to do with the additives.

[kenparry]

Often said that Jet A1 and diesel are the same stuff

There is a bit more to it. Diesel can have a wax point as high as (I think) about -10 deg C for European summer fuel, but Jet-A1 has to be able to tolerate tank and fuel system temperatures down to about -60 deg C.

[Brooklands]

Often said that Jet A1 and diesel are the same stuff

There is a bit more to it. Diesel can have a wax point as high as (I think) about -10 deg C for European summer fuel, but Jet-A1 has to be able to tolerate tank and fuel system temperatures down to about -60 deg C.
Also Diesel is produced to have a specific cetane rating (cf Octane rating) which Jet A1 doesn't need, so usually has a much lower one than Diesel.

In short they are similar, but not the same

Brooklands

[Cows getting bigger]

In a previous existence I used to work with military helicopters. To cut down on logistic chains, we would often use one type of fuel (F34 with FSII - broadly the same as JET A1) for both the turbine powered aircraft and our diesel support vehicles.

I'm not sure I would be playing with fuel types in a pathetically old school Lycoming/Continental design that should have been consigned to the scrap yard in the early 70s.