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SteinarN
Tar Sands
Joined: Sep 20, 2007
Posts: 95
Location: Norway
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 Posted: Tue Jan 15, 2008 7:20 am Post subject: Re: Aviation Fuel price record |
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| whereagles wrote: | back to the diesel/kerosene thing:
Kerosene has a lower resistance to compression than regular petrodiesel, right? If you put kerosene on a diesel engine, it seems to me that you run the risk of igniting it before compression is complete..
Now, is the above right or not, and is it called knocking or predetonation? |
In a diesel there isnt any fuel in the sylinder before ignition is ment to be and so there cant be any pre-ignition in a diesel. The fuel is injected shortly before the piston reaches top dead center and ignition follows almost instantly.
The diesel equivalent to gasolin oqtane number is the cetane number. This number describes how easily the diesel ignites when it is injected into the hot compressed gasses in the cylinder. The easyer it ingnites the better it is. Jet fuel has a lower cetane number imo it ignites not as easily and instantly as diesel when injected into the cylinder. This gives harder and more noisily starts especially when the engine is cold. This is caused by the delayed ignition of the fuel when injected into the cylinder. There will be quite som fuel injected before ignition take place. When ignition happens all the fuel already injected detonates all at once. When the engine become warm this phenomen is far less pronounced.
Another thing to be aware of is that jet fuel has far lower lubricating properties than diesel. It might be necessary to add two stroke oil to protect the dieselpump and injectors.
The fuelconsumtion increaces probably at least 10% when using jet fuel compared to diesel.
A relative of me work as a aeroplanemecanics. They get surplus fuel from emtying the fueltanks when doing maintenance. They are not allowed to fill the fuel back on due to regulatory rules. It cost money for the company to be rid of the fuel. Therfore the mecanics are allowed to take all the fuel they wish and several of them fill it on their dieselcars. |
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whereagles
Intermediate Crude
Joined: Aug 17, 2005
Posts: 580
Location: Portugal
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| Posted: Tue Jan 15, 2008 9:49 am Post subject: Re: Aviation Fuel price record |
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thanks
So, what happens if you put petrodiesel into an otto engine? I'm guessing it preignites.
And what if you put gasoline into a diesel engine? Nothing happens? (I.e. no flash, engine dies?) |
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SteinarN
Tar Sands
Joined: Sep 20, 2007
Posts: 95
Location: Norway
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| Posted: Tue Jan 15, 2008 10:09 am Post subject: Re: Aviation Fuel price record |
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| whereagles wrote: | thanks
So, what happens if you put petrodiesel into an otto engine? I'm guessing it preignites.
And what if you put gasoline into a diesel engine? Nothing happens? (I.e. no flash, engine dies?) |
If you try to run a petrol engine on diesel you wouldnt get it to start. The diesel fuel doesn't evaporate easily enough so there will not be any air/fuel vapormicsture in the sylinder, only droplets of diesel. If the engine is very warm you might get the diesel to evaporate enough to create a combustible fuel/airmicsture to start it, but then it would preignite or at least detonate at ignition as the diesel fuel has way too low oqtanrating.
If you try to run a diesel engine on petrol you wouldnt get it to start either. The petrol doesn't ignite due to way to high resistance to selfignition. Besides you would almost instantly and totaly seize your fuel pump and injectors due to the completely lack of lubricating properties of the petrol. |
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AirlinePilot
Moderator
Joined: Apr 05, 2005
Posts: 2472
Location: South of Atlanta
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| Posted: Sun Jan 27, 2008 3:05 am Post subject: Re: Aviation Fuel price record |
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Update:
Jet fuel has backed off nicely at 2.60/gal(from around 2.80) and AVGAS remains about the same around 4.68 this week.
Thats a definite relief for the moment for the airlines. |
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AirlinePilot
Moderator
Joined: Apr 05, 2005
Posts: 2472
Location: South of Atlanta
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| Posted: Fri Feb 08, 2008 12:22 am Post subject: Re: Aviation Fuel price record |
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4.64 for Avgas
2.58 for Jetfuel.
Oh what a relief it is!!!!!
NOT!!!! We will see come this April but I do believe when I started this thread back in April last year things were markedly better...
"Avgas (small aircraft 100LL) National average 4.15 gal
Jet Fuel Airlines Natioanl average 2.03"
Those prices had been UP at least several cents since prior to when I started tracking the data. I wonder where we will be next year at this time???? |
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UncoveringTruths
Intermediate Crude
Joined: Nov 04, 2004
Posts: 895
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| Posted: Tue Feb 19, 2008 1:04 pm Post subject: Re: Aviation Fuel price record |
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| Quote: | FORT WORTH, Texas - Airline pilots warned the Federal Aviation Administration they are being forced to fly with dangerously low fuel reserves, according to documents.
NBC 5 uncovered documents in which pilots complain to the FAA that their airlines are putting the cost of fuel above the cost of lives.
"A combination of minimum fuel flight planning with unrealistic flight plans combine to create hazardous fuel situations," one 737 pilot wrote.
According to the documents, pilots from nearly every commercial airline warned that management eager to decrease the weight of its planes are having aircraft carry the minimum amount of fuel allowed. The lighter the aircraft, the less fuel it burns.
"Management is juggling, and what they do by doing that, is they decrease the margin of safety," Capt. Carl Schricker of the Allied Pilots Association said.
Pilots and air traffic controllers said the airlines' effort to conserve expensive jet fuel have led to an increase in emergency landings and unnecessary diversions. |
Airlines Forcing Pilots To Fly With Low Fuel
_________________
It's a cold cold world when a man has to pawn his shoes. |
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AirlinePilot
Moderator
Joined: Apr 05, 2005
Posts: 2472
Location: South of Atlanta
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| Posted: Tue Feb 19, 2008 3:00 pm Post subject: Re: Aviation Fuel price record |
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I think the real problem is going to not be one of safety but of convenience. There is always enough fuel usually to make it to the destination safely plus some legal reserve. The problem will come as there will be more diversions when weather and traffic situations warrant it. Meaning we wont be able to hang around as long waiting for weather or the traffic back ups to improve.
I'll never hang around below a certain fuel amount before going somewhere else to get gas. It just means more of that really. It's not a dangerous or safety related issue unless the pilot makes a poor decision which puts him in some kind of box without options.
Thats why you want experienced folks up front driving you around the busy skies.  |
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UncoveringTruths
Intermediate Crude
Joined: Nov 04, 2004
Posts: 895
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| Posted: Tue Feb 19, 2008 3:05 pm Post subject: Re: Aviation Fuel price record |
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| AirlinePilot wrote: | I think the real problem is going to not be one of safety but of convenience. There is always enough fuel usually to make it to the destination safely plus some legal reserve. The problem will come as there will be more diversions when weather and traffic situations warrant it. Meaning we wont be able to hang around as long waiting for weather or the traffic back ups to improve.
I'll never hang around below a certain fuel amount before going somewhere else to get gas. It just means more of that really. It's not a dangerous or safety related issue unless the pilot makes a poor decision which puts him in some kind of box without options.
Thats why you want experienced folks up front driving you around the busy skies. |
After photographing 3 class A Mishaps I don't fly and this JIT fuel issue just compounds my grounded status.
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It's a cold cold world when a man has to pawn his shoes. |
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AirlinePilot
Moderator
Joined: Apr 05, 2005
Posts: 2472
Location: South of Atlanta
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| Posted: Tue Feb 19, 2008 8:36 pm Post subject: Re: Aviation Fuel price record |
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| I've seen a few class A's myself Truths. Never a fun or uplifting sight. |
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pup55
Expert
Joined: May 26, 2004
Posts: 3696
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| Posted: Fri Feb 22, 2008 2:34 pm Post subject: Re: Aviation Fuel price record |
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April 15, 2007: Avgas: $4.15, Unleaded $2.92
Now: Avgas: $4.69, Unleaded $3.09
Unleaded increase:5.8%
Avgas increase: 13.0%
Unleaded is at its seasonal low, as far as demand is concerned. I do not know about Avgas, but I would suspect similar. |
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AirlinePilot
Moderator
Joined: Apr 05, 2005
Posts: 2472
Location: South of Atlanta
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| Posted: Mon Mar 03, 2008 12:13 am Post subject: Re: Aviation Fuel price record |
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OUCH!
4.73 for avgas today and 2.86 for jet fuel national averages.
I do believe we are now seeing the refiners recoup the slow periods from last summer and fall. Demand is still strong across the board.
Prolonged prices in these ranges will spell definite trouble for airline earnings. I doubt with these numbers it's even possible to make money. It has too big an impact to the bottom line.
This is nothing short of ugly. |
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AirlinePilot
Moderator
Joined: Apr 05, 2005
Posts: 2472
Location: South of Atlanta
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| Posted: Mon Mar 10, 2008 7:48 pm Post subject: Re: Aviation Fuel price record |
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Avgas... 4.78
jetfuel .... 2.92
Yikes. |
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Isochroma
Tar Sands
Joined: Jul 22, 2007
Posts: 20
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| Posted: Tue Mar 18, 2008 4:57 pm Post subject: Done |
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The commerical aviation industry owes its existence to cheap oil, and with that gone, so too will go the industry. There is no easy substitute, like with cars.
Cars can (and already are) being made which run on the energy stored in batteries. As gas prices rise, people will be able to switch and enjoy their massively higher energy efficiency.
However, batteries do not have the energy density to run commercial aviation, and never will. In other words, commercial aviation needs hydrocarbon fuel; it is locked-in. For the comparison below, I chose the best battery from the source table available at this time.
Energy Density of Energy Storage Materials:
Secondary Lithium - ion Polymer: 0.396 MJ/kg
Energy density of jet fuel: 42.8 - 49.6 MJ/kg
Transwiki energy density was converted from Wh/kg to MJ/kg using this unit converter.
Airline industry will collapse by 75% in the next decade, if not sooner. What remains will serve the wealthy & government travel only. |
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Rabbit
Heavy Crude
Joined: Aug 30, 2005
Posts: 119
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| Posted: Tue Mar 18, 2008 6:22 pm Post subject: Re: Aviation Fuel price record |
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The Pathfinder-Plus solar powered aircraft set a new altitude record of 80,201 feet in 1998. Another unique solar-powered flying wing called Helios soared to 96,863 feet in 2001.
I don't think this helps much with those pesky passengers but it is interesting tech.
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www.ChrisGeigerPhoto.com |
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dohboi
Light Sweet Crude
Joined: Dec 05, 2005
Posts: 1274
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| Posted: Wed Mar 19, 2008 9:08 am Post subject: Re: Aviation Fuel price record |
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| I don't understand how airlines can stay in business at these prices. At what price do folks think flying really will become an economic impossibility for all but the military and super-wealthy? |
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