What are we discussing here ? Gust loads on large Aeroplanes or 747 conspiracy ?
Looking at the thread title I assume the first.
747focal, where do you take the 9g gust from ? Never heard of it.
Normally you assume gusts of 56 ft/sec at sea level to 44 ft/sec at 15000 ft to 26 ft/sec at FL 500 at cruising speed Vc, and half of it at Vd.
Gust load calculation is a real hard thing, and you have to rely on some assumptions like gust allevation. This gust allevation is assumed to be depending mainly on wingspan and air density, therefor strongly variing with altitude. The gust load calculation also depends on the slope of the Cl vs alpha curve, and the stiffness of the wing. Derived from measurements in older four engine prop transports, there is an emperical formula aviable, which is quite conservative and takes into account the typical stiffness of these old design wings.
More information can be found in
NACA-Report 997 ,
NACA-Report 1206 ,
NACA-Report 692 or
NACA-Report 1162.
To the best knowledge about gust loads today, it can be said that increasing the planes mass generally reduces maximum gust loads. On the other hand there are some problems (or better call it some aspects) with gust loads in the certification process, this forced Airbus and the authorities to agree on a modified rule, assumimg larger gusts than previously contained in the JAR/FAR25. The largest extent of a gust was assumed to be 12.5 times the mean wing chord, but not greater than 350 ft (which is 12.5 times the chord of a 747). This has been adopted to the new larger wing of the 380, the value has been increased to 435 ft, while 12.5 times the A380 length would have been only 425 ft. So some more safety reserve has been planned in.
I won´t support the idea, that a larger structure ´absorbes´ more energy. Larger structures tend to be not only heavier, but also much stiffer. Especially the large Doubledeck fuselage should be much stiffer in bending, than the 747 or A340-600 fuselage of similar length. And as the energy is force multiplied by displacement, the stiffer structure ´absorbes´ less energy ! (loading a stiffer spring with the same load results in lower energy absorbtion).
For new (and undoubtfully interesting) facts of the TWA800 crash, better start an extra thread.