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Guest groundpounder75

Why are all 747-400 weights different?

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Looking inside the Aircraft .cfg files for 3 different FS2002 B747-400 reveals that the empty and max weights are different for all of them.For example , the empty weight for the default aircraft is 401,000 lbs plus 40,000 cargo, the POSKY is 546,000 with no cargo, the MELJET is 490,000 plus 40,000 cargo.The maximum wieght for these 3 are 875,000, 928,000 and 910,000 respectively.I am reading a book called " Flying the big jets " by Stanley Stewart - the whole book is about B747-400 operations. He says "AVERAGE WEIGHTS FOR A B747-400 ON AN 8 HOUR FLIGHT ARE: - OPERATING EMPTY WEIGHT (INCLUDES PILOTS AND OTHER AIRCRAFT STAFF) 407000 LBS , PAYLOAD 90000 LBS, FUEL 220000 LBS (OF WHICH 20% IS RESERVE)AND TAKEOFF WEIGHT IS 717000 LBS."Now these figures seem to indicate that the default weights shown are the most accurate. It is also interesting to note that he says that the max landing weight is 627000 lbs - so this means that you should have more than around 100,000 lbs of fuel onboard when landing.Barry

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>For example , the empty weight for the default aircraft is >401,000 lbs plus 40,000 cargo, the POSKY is 546,000 with no >cargo, the MELJET is 490,000 plus 40,000 cargo. Maybe you should ask all of those authors where they got their figures from?

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Check out the Boeing web site for some good information on the 744. There is a section on their web site dedicated airport planning information for all of the Boeing planes. You will be able to get all the weight information for the 744 here. There is a different ZFW for each of the 3 engine configurations but MTOW and landing weights remain the same. Usually the ZFW is around 400,000lbs but it varies from airline to airline and the airplanes configuration. The max ramp weight is 877,000lbs and MTOW is 875,000. In the aircraft.cfg files some designers just modify the 'empty_weight' to reflect a loaded 744 instead of having 'station_load.0' etc to represent different loads. The PSS aircraft.cfg file uses many different 'station_load.x' sections to reflect a more realistic loaded 744 instead of just modify the 'empty_weight' to reflect the load. Also, when the 'empty_weight' is modified it changes the MOIs. The moments of inertia are based on the 'empty_weight' so if it is changed the MOIs need to be re-calculated. Personally I have figured out the weights for the 744s based on the airport planning guides and using the PSS Load Edit to set up the weights for each flight. The ZFW should be adjusted for each of the 3 engine configurations so when you use the PSS Load Edit you can have a fully loaded 744, with a ZFW of 542,500lbs. This only pertains to the passanger 744 and not the 744F or ER. When I download the Posky planes I change all the weight sections so I can use the PSS Load Edit with them. I saw the samething you are bringing up and I just changed the weight values to what they should be.I have also read that one of the major airlines that flies 747-400s have a target of 19000lbs of fuel remaining when landing. Hope this helps.

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