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Author Topic: B767 Fuel Consumption too low  (Read 779 times)

Online MikeS

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B767 Fuel Consumption too low
« on: May 08, 2018, 03:45:10 AM »
Just noticed in GW2
Huge difference in fuel consumption between A310 and B767. Comparing them with same engine model and same MTOW,
the difference is +32% higher on the A310

A310-300      with MTOW 160.000KG and CF6-80C2 Fuel Consumption: 5530 kg/hr
B767-200ER with MTOW 159.211KG and CF6-80C2 Fuel Consumption: 4190 kg/hr

Compared to other aircraft, it's clear the B767 figures are too low. Almost no difference to the B757 with much lower MTOW!

The following study shows the B767-200Er with CF6 engines consuming 1711Galons/Hr= 5233KG/hr which seems a lot more reasonable:

https://www.defenseindustrydaily.com/files/Boeing_KC-X_Fuel_Costs_Report_2007-11.pdf

Thanks
Mike
« Last Edit: May 08, 2018, 03:48:06 AM by MikeS »

Offline Zobelle

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Re: B767 Fuel Consumption too low
« Reply #1 on: May 08, 2018, 04:13:51 AM »
I think it's just right TBH.

Online MikeS

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Re: B767 Fuel Consumption too low
« Reply #2 on: May 09, 2018, 01:36:17 AM »
Doing some research:

According to Flight International's 1997 Commercial Aircraft specs:
https://www.flightglobal.com/pdfarchive/view/1997/1997%20-%202218.html

   Fuel Consumption KG/HR    at     max cruise speed     -    long range cruise speed

A310-300                                           4.690                                     3.730
B767-200ER                                      5.370                                     3.674
B757-200                                           5.350                                     2.885

A300-600R                                         5.120                                    4.300

The data show similar results for A310-300 & B767-200ER as expected and a good difference to the lower weight B757-200

I also added the A300-600R because in AWS it consumes less fuel than a A310-300 while according to these figures it should be the other way around.

I know checking and cross checking these figures against several sources is a major headache ....

Mike

Offline Zobelle

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Re: B767 Fuel Consumption too low
« Reply #3 on: May 09, 2018, 01:28:20 PM »
767 is narrower than A310.

Nuff said.

Online MikeS

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Re: B767 Fuel Consumption too low
« Reply #4 on: May 09, 2018, 03:22:01 PM »
I went on with my extensive online search for better comparable data but unfortunately I couldn't find any other publication other than the one from Flight Global already mentioned above.
From the many forums with pilot talk and flight sim optimizations etc it seems the data for the 767 is generally ok but the ones for 757 and A310 are too high.

The problem comparing fuel consumption in AWS is that it is stated as an average, considering a full flight profile without indication of flight time used for calculation.
A better number for comparison would be: Fuel consumption per hour during cruise

So: If the numbers provided by AWS for the B757 are for a 2 hour sector and the numbers for the B767 are for a 10 hour sector, then sure the numbers would
add up. The same applies to the A310. If AWS took a short sector as average then the numbers would indeed appear higher due to the climb penalty and the
disproportionate extra weight for carrying reserves.

So in order to be able to compare apples with apples, a standard fuel consumption per hour in cruise would be a lot more helpful, especially for longer range a/c.

I am tempted to order an a/c each of A300/A310/B757/B767 and put them on an identical 3000nm flight to see the fuel consumption results. If anyone has several of these birds in fleet and would like to share their results that would be really nice.

Cheers!

Mike

Offline Sami

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Re: B767 Fuel Consumption too low
« Reply #5 on: May 09, 2018, 04:42:10 PM »
If you have data on per-flight basis that is ok too. Just need the stage length (preferrably miles) with possibly even the actual airport/route pair (for wind effect) and a/c weight during that flight (major factor) and the total fuel consumption (trip, or taxi+trip).  Or the actual cruise fuel flow per weight per FL is also a very good source.

(quick look at your data, it's either the A310 or B767 that is wrong in AWS data probably, as they should be rather close? But in my mind 757 vs 767 ratio in AWS is roughly correct .. sadly don't have 757 flight manuals here anymore to check)
« Last Edit: May 09, 2018, 04:44:39 PM by Sami »

Online MikeS

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Re: B767 Fuel Consumption too low
« Reply #6 on: May 10, 2018, 02:09:58 AM »
I managed to find the training manual for Interflug's A310-304s from 1989 (GE CF6 engined with MTOW 157.000) :

http://www.interflug.biz/Flugzeuge/A-310/Ausbildung/Ausbildungshandbuch/Airbus%20A-310-304%20NOV1989.pdf

The manual shows 3 pages of tabulated fuel consumption scenarios, ranging from 200nm to 2100nm and flight levels 290 to 390.   (pdf pages 8-11)

I assume:
The highest relative consumption is for a  200nm@290FL    : 2800KG for 38min  =  4421kg/hr
The lowest  realtive consumption is for a 2100nm@390FL  : 18400KG for 4:50hr =  3807kg/hr

so the average should be somewhere in between I suppose ~4114kg/hr ? (Result very close to AWS B767-200ER with same engine&MTOW  4170kg/hr) !!
AWS figure currently at: 5320kg/hr (+29%)

Thanks
Mike

Offline Zobelle

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Re: B767 Fuel Consumption too low
« Reply #7 on: May 13, 2018, 07:48:49 AM »
So the tables turn. A310 now is too high and 767 is perfect.

An agreeable solution.

 

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