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Old 25th Jul 2018, 11:04
  #99 (permalink)  
KenV
 
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Originally Posted by Volume
There probably is a good reason (or actually two more...) why Boeing never changed the 747 to full double deck. Looking at the dreamlifter, they may have been able to do so, but actually it does not make sense.
The dreamlifter is mostly non pressurized, so not applicable. Boeing chose to stretch the 747 fuselage rather than just extend the upper deck because they wanted to increase passenger AND freight capacity. Extending just the upper deck increases passenger capacity while reducing freight capacity.


Airbus once had a major market advantage for the A300 compared to the Boeing products, because they offered more cargo space which allowed the airlines to do additional profit. On the A380 they did the opposite, and it hurts. Initially they went for a conventional environmental control arrangement, but later moved it to the wing roots to gain some more cargo space.
In Boeing aircraft "a conventional environmental control arrangement" puts the system in the wing to body fairings OUTside of the fuselage, so it does not reduce cargo hold capacity.

They also (compared to the 747) selected a body gear arrangement which allows additional cargo space between, still it is not that much.
That's the big advantage of the 777 vis a vis cargo space. There is no body gear. With the exception of the centerwing structure, the entire lower lobe is available for cargo. No gear retracting into the body.


They still have to proof that this does not only look like a clever design, but actually works in real service life... Adding complexity rarely pays off.
The folding wing design on the 777X is exceptionally simple. The flap system on a 747 is far far more complex and "actually works in real service life." For that matter the landing gear retraction/extension system on a typical airliner is far more complex than the 777's wing fold mechanism and they certainly "actually work in real service life."

Last edited by KenV; 25th Jul 2018 at 15:05.
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