CoolGuy
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Additional Fuel For Extra Weight

Tue Apr 01, 2008 4:08 pm

How much extra fuel is used on an aircraft per additional pound (on your choice of aircraft and length of flight, etc.) For example, I am trying to calculate the amount of CO2 that I produce by going on a flight. I don't want to just divide the total fuel expenditure by the number of people onboard.

Of course, an extra passenger means that extra fuel might be loaded onboard to handle the weight of someone heavier than myself+my baggage and the weight of that fuel requires extra burn too, etc.

I once performed a calculation based on my best guesses and found that 'carbon offsets' that were being advertised were about 10 times higher than they should be!
 
flipdewaf
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Joined: Thu Jul 20, 2006 6:28 am

RE: Additional Fuel For Extra Weight

Tue Apr 01, 2008 4:13 pm

Check out the breguet range equation, that should give you some idea.

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longhauler
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RE: Additional Fuel For Extra Weight

Tue Apr 01, 2008 6:06 pm

It depends on the aircraft of course. But to give you a guideline, on an E190, on a four hour flight (YYZ-PHX was the flight plan I was using), you need 135 Kgs of fuel increase for every 1000 Kgs of increase of take off weight. This is for the entire flight.

Therefore, for 100 Kgs for one passenger and baggage, one would burn 13.5 Kgs of fuel.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
prebennorholm
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RE: Additional Fuel For Extra Weight

Tue Apr 01, 2008 6:48 pm

Longhauler's example is a very good example for fairly short routes.

But please don't just multiply with the distance factor when going really longhaul.

The extra fuel needed for carrying Longhauler's 13.5kg extra fuel accounts for something like one kg of those 13.5kg. But when going really longhaul, then the weight of extra fuel easily becomes more than the weight of the one extra pax. Consequently the fuel needed to lift the extra fuel will also be more than the extra fuel to lift the extra passenger.

And with that extra fuel you will need "extra, extra" fuel to lift that extra fuel. Extra fuel consumption grows exponentially with distance, and that becomes significant on very long routes.

So while Longhauler's example is correct, then if you go on a five times longer flight, then your extra fuel consumption could be not five, but seven, eight, nine or ten times higher.
Always keep your number of landings equal to your number of take-offs
 
roseflyer
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RE: Additional Fuel For Extra Weight

Tue Apr 01, 2008 7:02 pm

To follow on, the additional fuel of that one additional passenger can get significant when you are talking ultra long haul flights. You get to the point that you not only have to carry the extra weight of the passenger, but the extra fuel has to be carried as well. It can get almost to the point of needing an extra pound of fuel for every extra pound or two on board a flight like SQ's EWR-SIN.
If you have never designed an airplane part before, let the real designers do the work!
 
wilco737
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RE: Additional Fuel For Extra Weight

Tue Apr 01, 2008 7:40 pm

hey guys,

we have a rule of thumb for the additional fuel burn. Take the mileage of the planned flight and divide it by 100. This is the percentage of the extra fuel you will burn just to carry this extra fuel with you.
So if a flight is 5000NM long you need 50% of the extra fuel you took just to have it with you. Means: 1000kg extra fuel for a 5000NM flight, then you arrive at the destination with 500kg extra only, because the other part you just burnt.

We have another info on the flight plan how much more fuel you burn for every 1000kg extra weight you carry with you. And this rule of thumb gets pretty close to that.

WILCO737 (MD11F)
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longhauler
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RE: Additional Fuel For Extra Weight

Tue Apr 01, 2008 8:41 pm

I found this message string curious, so I logged onto our flight planning computer and pulled some actual flight plans of current actual flights. On these flight plans is a "fuel required for extra weight", should that arise. Basically it is the amount of fuel required to carry 1000Kgs of extra weight. This extra fuel required also includes the fuel required to carry the extra fuel. Divide by 10 for a 100 Kgs passenger and you get your answer. Some examples:

A319 ... YUL-YVR ...4:47 ...19.1 Kgs. (per extra 100 Kgs passenger)
B767 ...YVR-PVG ...12:06 ... 57.5 Kgs
B777 ...YVR-SYD ...14:16 ... 61.4Kgs
A330 ... LHR-YVR ... 9:12 ... 40.4 Kgs
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!

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