Originally Posted by Grunf
Barit1,
Small correction:
Not all floor beams/frames in tension since the cargo compartment is pressurized and therefore there are some floor beams and parts of some frames that are compression critical for pressurized loads.
OF COURSE the cargo (lower lobe) is pressurized. Otherwise there would be a pressure differential across the flat floor, tending to circularize it (as we saw 33 years ago in the DC-10 cargo door blowouts!)
By maintaining near-zero delta P on the floor -
o Upper lobe skin is in pure tension
o Lower lobe skin is in pure tension
o Floor is in pure tension, preventing the "kink" between the two from bulging out!
