Originally Posted by
III Corps
It appears that if there was a lack of confidence in composites, Boeing would not be making an airplane composed of almost 50% composites.
True. The issue here with the A330 (and all Airbus jets, potentially) is not the use of composites, its how they're attached to the frame of the aircraft and how the sheer loads are managed, particularly how Airbus' design manages the sheer loads of the vertical stab.
Most of the metals that make up the remaining 50 percent are found in very large forgings and castings at the highly loaded joints between composite structures and where the undercarriage is attached.
Although Boeing is treating the frame design as confidential, the one photograph of the frame/fuselage assembly that has been released shows a separate "foot" between the longitudinal hat stringers, to better distribute the shear loads.
Neither Boeing, nor Airbus, has figured out a way to use composites to resist the loads at the attachment points yet (due to the way carbon fibers work). This is the same general method (metal attachments) that Airbus has been using in their vertical stab join. It would be nice if Boeing and Airbus could share technology in this area, in the interests of safety. If it ultimately comes out that there is an issue here @ the stab join attachment points, one would hate for the 787 to suffer from the same issues if it could have been prevented. Of course, then again, that may be the saving grace - Boeing had to design the attachment point themselves, rather than using Airbus' design (which does have a remarkable safety record, for the time being).
The days of the DC-8 and 747 are behind us. 'Estimate the load, then build it twice as strong' is no longer the philosophy.