Fuel density effect on range/fuel capacity US West coast against south east Asia

[Santos]

Hello fellow drivers,
There is an article from a beautiful website that many of you know www.code7700.com it talks about the effects of fuel density on range/fuel capacity..
It states that the fuel density in the US west coast is denser than the one found in south east Asia resulting in considerable effects in range/fuel capacity.

http://code7700.com/fuel_density.htm

any lucky pilot on a similar operation cares to share his view on the matter.

Happy landings

[ahramin]

While I find most of Eddie's material excellent, I'm struggling with that article. Aside from the odd 414, any corporate aircraft is either a turboprop or a jet. Either way, fuel flow is measured in pounds or kg per hour, not liters or gallons. When you uplift with a single point system, you tell the aircraft how many kgs of fuel you want and it uplifts that many. I know he's from a military background and they do strange things but I don't see how anyone could be surprised that if the airplane says you have 20 000 kg of fuel, you have 20 000 kg of fuel. For small aircraft with over the wing fueling you have to get the density and convert to liters or gallons for the uplift, but then how could you not know about density?

[clearmyside]

That has been my experience. Routinely planned a max uplift of 400lbs less than book leaving out of a popular SE destination, whereas in Europe for example you could "overfill" the aircraft on occasion, getting 80-100 lbs more than book.

[CpnCrunch]

The point he is making is that aircraft fuel tanks are limited by volume, so the weight of that fuel that you can carry will depend on the fuel density, and that depends on temperature.

[ahramin]

Yes, I'm just surprised that this is a surprise.

In any case, how often does this make a difference? In my career I can think of only 3 times where I needed full tanks.

[Eric Janson]

In any case, how often does this make a difference? In my career I can think of only 3 times where I needed full tanks.

Well - I was doing flights last year where we took full fuel.

The problem was that we couldn't get the published full tank value in the tanks. There are also sensors in the tanks that will stop refuelling when a certain tank level is reached.

I did one flight where full tanks was the minimum fuel. That ended up being almost 2000kg less than the figure on the flight plan. We needed to reduce payload by 1000kg. Flight time was 16 hours.

[valleyboy]

Simple example in smaller numbers but it is was very noticeable in the Arctic a few years ago when Yellowknife only used fuel supplied from "the wells" which produced a light weight fuel.

The difference in filling up a hawker 748 in Iqaluit as opposed to YK was 1500 lbs which translated into about 45 minutes of endurance.

In the heavy world I can remember always getting a specific gravity of the fuel upload and the fuel temperature.

I even notice the difference in mileage in my diesel truck from summer to winter and again in YK where they did burn P50 year round but even in the south when we switch from summer to winter weight fuel.

One of the factors is the higher fuel temperatures, especially in our winter months.

[Roar]

While I find most of Eddie's material excellent, I'm struggling with that article. Aside from the odd 414, any corporate aircraft is either a turboprop or a jet. Either way, fuel flow is measured in pounds or kg per hour, not liters or gallons. When you uplift with a single point system, you tell the aircraft how many kgs of fuel you want and it uplifts that many. I know he's from a military background and they do strange things but I don't see how anyone could be surprised that if the airplane says you have 20 000 kg of fuel, you have 20 000 kg of fuel. For small aircraft with over the wing fueling you have to get the density and convert to liters or gallons for the uplift, but then how could you not know about density?

Yes, you are correct 20,000kg of fuel is 20,000kg of fuel. What I believe Mr. Albright is getting at in code7700 with regards to range variations from fuel at various geographical locations is the Energy Content of that 20,000kg (or Energy Content per 1kg of jet fuel). Now we all understand that temperature has an effect on the density of fuel, if the fuel is warm it will be less dense and it may not be possible to get the 20,000 kg in the fixed volume of the fuel tanks and vice versa for cold temps.
The geographic issue referenced in code7700 is a fuel manufacturing composition difference. Think of it this way, the manner in which the jet fuel is manufactured in SE Asia gives you more “bang for your buck” gravimetrically (energy content per unit weight [kg]) vs West coast of NA where you get more “bang for your buck” volumetrically (energy content per unit volume [L]).
Which is better? That’s a complicated question. It would
Seem if one is looking for maximum range you’d want maximum energy content per unit volume, but if you were looking to carry maximum payload you’d want maximum energy content per unit weight.
I’m just guessing now but maybe that’s why SE Asia fuels are less dense is they have biased their fuel for short haul max payload whereas west coast NA has biased fuel more dense for max range...??

[ahramin]

The geographic issue referenced in code7700 is a fuel manufacturing composition difference. Think of it this way, the manner in which the jet fuel is manufactured in SE Asia gives you more “bang for your buck” gravimetrically (energy content per unit weight [kg]) vs West coast of NA where you get more “bang for your buck” volumetrically (energy content per unit volume [L]).

Was that a typo? Or are you saying 20 000 kg of Jet A from one source will not have the same range as 20 000 kg of Jet A from a different source?

[photofly]

The geographic issue referenced in code7700 is a fuel manufacturing composition difference.

Different density, therefore different volume/kg, but there's no suggestion in the article of different energy content per kg.

[Roar]

The geographic issue referenced in code7700 is a fuel manufacturing composition difference.

Different density, therefore different volume/kg, but there's no suggestion in the article of different energy content per kg.

True, but there has to be a reason for the resulting differences he discusses. here is an article by Chevron that dives into it.
https://www.chevron.com/-/media/chevron ... review.pdf

[ahramin]

The geographic issue referenced in code7700 is a fuel manufacturing composition difference.

Different density, therefore different volume/kg, but there's no suggestion in the article of different energy content per kg.

True, but there has to be a reason for the resulting differences he discusses. here is an article by Chevron that dives into it.
https://www.chevron.com/-/media/chevron ... review.pdf

The differences he discusses are differences in weight per volume, not energy per weight. 20 000 kg of fuel is the same everywhere in the world. The only time this matters is when you are limited by the physical size of your tanks, which in my experience is exceedingly rare.

On further reflection, Eddie's point that the specific gravity varies more by region than by temperature is interesting. If true, it's worth noting for the rare case where you are volume limited. In my experience the specific gravity of Jet A doesn't vary much in Europe or the Americas but I haven't operated in Asia.

[JoeShithe]

The fuel temperature usually drops through the flight anyway. Most flight planning systems have a route temperature analysis to statistically plan for routes with seasonal variation as well as monitoring for cold temp issues.

The only time we’ve compensated for temperature is when tankering from a warmer climate to somewhere where we uplifted cold fuel. When it mixes the total fuel indicated drops a few tons after about 30 minutes.

We would toss on a few extra tons to make flight plan fuel.

[Jerz]

I've recently ferried an aircraft from Sydney, Australia to Yellowknife. We could not get our tanks full at +37C. We were full by volume, but short of about 1000lbs , or 5% by weight. Heading North, as the OAT was getting closer to standard, we were able to load correct amount by weight. In Alaska when tanks were full by volume, we were over by about 1000lbs by weight. We see similar variations all the time between the Arctic at -40C in Winter and +30C in YYC in Summer. I believe it has more to do with fuel density ver temperature, then different fuel formulation.
For our type, short range jet, the difference between cold Winter and hot Summer can be as much as 25min of endurance. Definitely something to be aware of, if you need max range/endurance.