Victor Hotel From Australia, joined Aug 2000, 305 posts, RR: 2 Posted (11 years 4 months 2 weeks 20 hours ago) and read 1695 times:
Can someone tell what avaition Fuel mostly consists of, is it mostly Kerosene?, and the differences between them for example JetA, and Avgas or somthing? Thanks
VH
Illini_152 From United States of America, joined Jan 2001, 1000 posts, RR: 2 Reply 2, posted (11 years 4 months 2 weeks 12 hours ago) and read 1551 times:
Well, JetA is very similar to kerosene or diesle fuel and is what jets and turboprops run on. It has a very low octane rating, somewhere in the neighborhood of 40 or so.
AvGas is closer to the auto gas that you put in your car, except more tightly controlled. There are primarily two differant grades: 80/87 which is red, and 100LL which is blue. Both of these have a much higher octane rating than JetA, and contain tetraethyle lead additives. 100LL (100 low-lead) is the most common (at least in the United States), and contains about 10 times the ammount of lead that automotive gasolines did in the 1970's. These fuels are used in almost all piston engined aircraft today. Years ago there were other grades, a 100/130 grade that was green and a purple 130/145 if I recall correctly. These were used in the big propliners of the 50's. I remember hearing somewhere (could have just been hanger stories) that the Connies and such would keep the 130/145 in a seperate tank, and only use it for takeoff.
There are currently a number of engine manufacturers working on GA diesles that will run on JetA.
Happy contrails - I support B747Skipper and Jetguy
Jetguy From , joined Dec 1969, posts, RR: Reply 3, posted (11 years 4 months 2 weeks 12 hours ago) and read 1534 times:
Also, in a pinch, you can run avgas in many general aviation turbine engines. There are usually some restrictions (time and altitude) associated with the operation but you can do it. I've only had to do it a couple of times - once in a Turbo Commander and once in a Lear Jet. Both times the airport had run out of jet fuel. When it comes down to it, turbine engines will run on just about anything that burns and can be forced through their injectors.
Prebennorholm From Denmark, joined Mar 2000, 5810 posts, RR: 56 Reply 5, posted (11 years 4 months 1 week 6 days 9 hours ago) and read 1510 times:
My company (Shell Oil Co.) happens so sell a substantial part of the aviation fuel used on this planet. I can tell you:
Jet A1 IS kerosene. When we sell kerosene, then we take it from the Jet A1 tank. Of course way over 99% of the kerosene we sell is labeled Jet A1, but it all comes from the same tank at the refineries.
In addition we have developed a low smell type kerosene for kerosene lamps. But since a quarter of a gallon lasts for ages, then this is certainly a very special niche product which doesn't put much butter on my bread. It is not labeled kerosene, but "Lamp Oil".
That's the two types of kerosene we produce.
Most popular aviation gasoline for piston engines today is the Avgas 100LL. "100" is the octane number. "LL" stands for "Low Lead contents". Is was introduces some 30 years ago as a substitute for both Avgas 80 and Avgas 100. The old 100 had too high lead contents for engines designed for the lead free 80. It would tend to foul the spark plugs in some engines which were designed for Avgas 80.
Lead contents in 100LL is about 66% of what we were used to in the 70'es for cars, and about three times more than car gas when restriction were tightened in the 80'es (now cars are lead free of course).
Aviation gasoline differs from car gasoline in other ways. It contains less very volatile hydro-carbon molecules. This prevents that the gas starts boiling in the aircraft tanks at low pressure at high altitude. It has the disadvantage that the aircraft engine will have a more rough running while it is warming up. That is one reasom why you don't even dream about taking off until the engine is warm.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
Jetguy From , joined Dec 1969, posts, RR: Reply 6, posted (11 years 4 months 1 week 6 days 6 hours ago) and read 1494 times:
Oh, by the way, I forgot to mention that although turbine engines can run quite well on avgas (or a lot of other stuff for that matter) piston engines WILL NOT run on jet fuel. It seems that every year there are several fatal accidents caused by the misfueling of piston powered aircraft.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 8, posted (11 years 4 months 1 week 4 days 16 hours ago) and read 1440 times:
Illini 152,
Kerosene based fuels have a Cetane rating, not an Octane rating. What's your source for "...an octane rating of 40 or so" for jetA?
Prebennorholm From Denmark, joined Mar 2000, 5810 posts, RR: 56 Reply 9, posted (11 years 4 months 1 week 4 days 12 hours ago) and read 1432 times:
EssentialPowr wrote:
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Kerosene based fuels have a Cetane rating, not an Octane rating. What's your source for "...an octane rating of 40 or so" for jetA?
---------------------------
Correct! Jet A1 burning piston engines can only be diesel type engines. A diesel engine does care about octane number.
Octane number is a figure telling how resistant the fuel is agains self-igniting under high pressure and heat. In a diesel engine the fuel MUST ignite the same instant it is injected into the combustion chambre.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 10, posted (11 years 4 months 1 week 4 days 10 hours ago) and read 1421 times:
I understand the Diesel cycle and compression ignition. I am simply wondering what the source of his info is..SAE? API?
Gas stations in the US, as you know, market grades of gasoline based on octane rating...but not diesel. If octane values relate to vapor pressure (not flash point)characteristics, what does cetane quantify?
Prebennorholm From Denmark, joined Mar 2000, 5810 posts, RR: 56 Reply 11, posted (11 years 4 months 1 week 4 days 8 hours ago) and read 1407 times:
Yeah, all over we normally have four gasoline grades. But it will change soon. Higher than 95 octane is very expensive to produce without adding some stuff named MTBE. And MTBE gets banned in more and more places due to environmental reasons. The vast majority of cars produced during the last 10 years are optimized for 95 octane.
Cetane number:
In the very short and simplified version the cetane number quantifies the ability of the fuel to evaporate and ignite fast. The faster it evaporates and ignites, the higher value. The value for ordinary diesel oil is in the 50 - 52 range.
On what we sell we guarantee minimum 50. For the street busses in Copenhagen city, which are equipped with every gadget imagineable to limit polution, we produce a special brew, for which we among several other parametres guarantee minimum 52 cetane.
Large ships mostly burn a cheaper, less volatile, and completely black oil normally called fuel oil, which comes in different qualities. It has a much lower cetane number. It works okay only because those engines rotate much more slowly and therefore leaves more time for the combustion process. They also have a slightly higher compression ratio which heats the air slightly more before the fuel is injected. Those engines are, however, normally started on ordinary diesel oil and won't burn fuel oil efficiently until the engine is warm.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
L-188 From United States of America, joined Jul 1999, 28959 posts, RR: 66 Reply 12, posted (11 years 4 months 1 week 4 days ago) and read 1402 times:
EssentialPowr:
Think of it as a ratio.....The higher the octane rating the lower the cetane rating is by default. This is also why oil that makes great gasoline generally will not make a great grade of jet fuel.
We went over this great length in the two engine theory classes I had last sememster, the instructor was on a big trip on the diesel aircraft engine.
I am going to respectivly disagree with Prebennorholm about one point. In the U.S. the cetane number is usually about 30 for diesel fuels. This is why the diesel trucks over here make that loud clank, clank, clank noise when they are running. You don't hear the trucks in Europe do that, due to their higher cetane number. I was told in Japan the number is closer to 60.
Also Jet fuel doesn't have a set cetane rating, which could make it real interesting for use in a aircraft piston diesel engine. Since the cetane number determines at what pressure in the cylinder the fuel/air mix will light off. If you have a fuel where the cetane rating varies then you could have the cylinder light off at different pressures depending of where you fuel.
Of couse this would be the problem with a normally asperated diesel(No that is not a contradiction in terms). It shouldn't be that big of deal in the case of a fuel intjected engine.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
Prebennorholm From Denmark, joined Mar 2000, 5810 posts, RR: 56 Reply 13, posted (11 years 4 months 1 week 3 days 17 hours ago) and read 1404 times:
L-188 wrote:
-------------------------------------
...If you have a fuel where the cetane rating varies then you could have the cylinder light off at different pressures depending of where you fuel.
Of couse this would be the problem with a normally asperated diesel (No that is not a contradiction in terms). It shouldn't be that big of deal in the case of a fuel intjected engine.
-------------------------------------
Dear L-188, all diesel engines have a fuel injection system, and not like most gas cars of today where the fuel is injected in the inlet manifold and gas/air mixture is loaded into the combustion chambre before the compression stroke.
Diesel engines breathe clean air, and then the fuel is injected into the combustion chambre at the end of the compression stroke. And it burns while it is being injected.
Therefore different cetane numbers doesn't mean much as long as the number is always high enough for the engine design. The timing of ignition is not managed by the cetane number, but by the fuel injection system.
And then I am really surpriced to learn that US diesel oil has such a low cetane number. But now I understand why small diesel cars are practically absent in the states. In some European countries - France, Italy, Portugal for instance - close to half of all small cars are diesel powered. And with todays technology you hardly notice the difference. The only difference in operation is that when turning the starter key, then you wait 2-3 seconds for the glow plugs to heat up before you engage the starter engine. Then it always starts immediately, while a gas engine has to turn 3-4-5 revolutions before it fires.
In older days diesel cars tended to be a little slow. Today there are Audi and Mercedes-Benz diesel saloon cars with close to 200 HP going 130-140 mph. That's enough. And a small VW Golf diesel with 115 HP goes 120 mph. And in Germany they do that on soya bean oil as well - with just a little more McDonalds smell.
So it should not be a big problem to make small diesel aircraft engines in the 100 - 200 HP range.
The biggest problem is probably to have the engine manufacturers convince their investors that the market is big enough to turn out a substantial profit.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
JETPILOT From United States of America, joined May 1999, 3128 posts, RR: 37 Reply 14, posted (11 years 4 months 1 week 3 days 17 hours ago) and read 1402 times:
Socata Aircraft is already selling their popular Caribe line of GA planes with an option for a diesel motor.
L-188 From United States of America, joined Jul 1999, 28959 posts, RR: 66 Reply 15, posted (11 years 4 months 1 week 3 days 11 hours ago) and read 1385 times:
Yeah I vapor locked on that.......But be careful about saying that as an absolute. You know if somebody wanted to build a carburated engine that burned diesel fuel they could. And a long time ago somebody probably did. For some reason I keep wanting to think that a couple of those big single cylinder marine diesels that they use on supertankers are carburated but I can't confirm that.
Yeah that is the number I heard quoted in that engines class. I guess that it is cheaper to manufactuer fuel with the lower cetane number. But it goes to show why explain why some european motors have a bad reputation for being fussy in this country. We had a forklift and an air start bottle that where both powered by the same four cylinder Perkins Diesel. They where both very, very fussy about starting when it was cold off. My theory is that the low cetane number of our diesel(Jet Fuel) didn't allow the fuel/air mix to fire off when starting cold. We ended up putting a coolant heater on both engines that was big enough for two of those engines. They usually would start pretty easily when those had been plugged in for an hour or so.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
Prebennorholm From Denmark, joined Mar 2000, 5810 posts, RR: 56 Reply 16, posted (11 years 4 months 1 week 2 days 16 hours ago) and read 1373 times:
Dear L-188
Carburated engines burning diesel fuel have been made. Here they were the rule in small fishing boats from the 30'es, and some of then kept on well into the 60'es. They were very low power, but huge one cylinder engines, and I can still hear them - donk, donk, donk.
I am, however, pretty sure that Herr Diesel would rotate in his grave if we call them Diesel engines.
We called them glowhead engines, and it tells a little about their operating method. They had some heated device in the top for ignition, probably much like a glowplug in small model aircraft engines. In fact I don't know much more. Only that they were real beasts to get started. Some fishermen had no serious problems operating them, and some just never learned the tricks.
They are all gone now except on museum boats.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
Justanyone From , joined Dec 1969, posts, RR: Reply 17, posted (11 years 1 month 3 weeks 17 hours ago) and read 1276 times:
Soybean Oil for Diesel / Jet Use ?
Pardon my lack of chemical knowledge, but I'm wondering if anyone has cetane ratings for Soybean oil ? I've read elsewhere (as well as above) of it being used in Diesel engines, and thus would work in aviation diesel piston engines, but what about using it in aviation?
Are there any known instances of people using this fuel?
Per another thread here, what would the gellification / solidification / freezing point be for Soya oil, and would this be sufficient for high altitude and thus low temperature operations?
-- Kevin
kevin@justanyone.com
http://www.JustAnyone.com
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