Originally Posted by
Volume
Compared to the design of some aircraft carrier operated military aircraft or some folding wing motorgliders I do not think so.
There are for example 4 individually actuated latch pins, there is a locking mechanism and there is a folding actuator meaning 6 actuators where most landing gears have only two...
And the folding axis is not perpendicular to the wing centerline, making the structure around it extremely complex. (The alternative would have been more air loads during taxi)
Where the comparison with the 747 flap system goes astray, is that the folding wing folds in the direction of the main force (up) where the track system folds in the direction of the wing cord (and down). The flap system thus needs less safety measures to stop it from extending or retracting due to aerodynamic forces.
Originally Posted by
Volume
I was more thinking about aerodynamics and weight. Extending the conventional pressurized 747 upper deck all the way back to the tail would have been relatively easy (they partially did it on the -300 EUD and the -400, they could have streched it even further), but would have created the same issues the A380 has (as you correctly identified): lack of cargo space per passenger and lack of cargo weight capacity.
Not talking area ruling and trassonic drag...
KLM stretched the the top deck of their 742 to the length of the 743. This actually ended up reducing overall fuel burn due to lower drag, even though weight was added.
https://www.airlinereporter.com/2012...pper-deck-sud/