Originally Posted by
threeighteen
Uh, humans. Humans create moisture. Do you have any idea how much water a human being expels in an hour of air travel? it's about 100ml/hr. Multiply that by 200+ people packed in an airbus on a 5hr transcon and you get 100 LITERS of water built up. Higher aircraft utilization means more time spent flying around with condensation built up inside.
What is the cabin air frefresh or replacement rate in most modern large airplanes? Do you know?
Approximately every 2-3 minutes the cabin air is completely replaced, in that it takes approximately that period of time to flow an entire cabin's volume through the packs and out the outflow valves. What's coming in is very dry air. The relative humidity at altitude is considerably less at lower altitudes.
Your ridiculous comparisons to a home air compressor on the ground, and cabin air obtained from a dry source in a low pressure cabin holds no water.
Ever wonder why one tends to dehydrate on long flights at altitude, and should keep drinking, or why skin tends to dry out on long flights? It's not a humid place at altitude, especially given the fact that large volumes of very dry air are being pumped into the cabin.
Nearly all condensation takes place at lower elevations on descent, and it's not a result of pressurization, but of condensation due to a cold fuselage descending into warmer, humid air.
As for maintenance experience with composites, you clearly wouldn't know, but we've been working composites for many decades now. You're not familiar with fiberglass work, honeycomb structures, bonding, vacuum bagging, or other common maintenance facets of constructing and repairing composite structures, but most mechanics are. Go figure.