|Quoting western727 (Reply 10):|
I thought the 380 does NOT have a composite fuselage...and thus has similar cruise pressure/humidity levels as, say, a 330 or 777?
Approximately 25% of the A380 is made from composite materials. GLARE is used in the upper fuselage and CFRP in the rear pressure bulkhead, centre wing box and wing ribs among other area. In fact, I think I'm right in saying that the A380 uses more composite materials (by measure of sheer weight) than the 787.
However, the point in hand. The A380 does have similar pressure/humidity levels to the 787. Increased corrosion is the main issue when you decrease the cabin humidity (due to the higher level of moisture in the air). CFRP is more resistant to corrosion when compared to aluminium. This enables the 787, with its increased use of composites, to utilise a higher cabin humidity.
I presume the A380 uses extra corrosion protection when compared to previous aircraft to achieve the desired corrosion resistance. I'm not entirely sure on the specifics though (I think it may be achieved using humidifiers).
One last point I would make, however, is that 50% of the 787 is not built using composite materials. Those areas of the aircraft are vulnerable to the increased corrosion so I'm sure similar methods of protection are also used on the 787.
[Edited 2012-05-07 10:34:20]