Lonewolf, JD-EE, in searching for some idea of the wreckage condition and layout, the China Airlines A300 stall accident at Nagoya in April of 1994 may be of interest.
The aircraft stalled on short final, (to keep this short, the reasons for the accident are in the report,
here), and impacted in essentially the same attitudes as the BEA has described.
From the report (translated from the Japanese):
"3.1.4.1 From the DFDR records, it is estimated that the aircraft stalled, then descended steeply with wildly changing roll angle, and impacted the ground.
The spot where the aircraft hit the ground was an unpaved, flat landing area. There were marks left on the ground surface that clearly identified those portions of the aircraft which had hit the ground. From the shapes of the marks and these positional relationships as well as the condition of destroyed landing gears, it is inferred that on impact, the aircraft was in a somewhat left-wing down, nose-up attitude, and was in an almost level attitude." - p67,
The impact would be essentially the same, but the hard land surface in the Nagoya accident permitted a longer/wider distribution of wreckage with perhaps far more secondary damage as parts collided with each other and ground objects before coming to rest.
A water impact, as has been pointed out, would be as hard, but once the initial impact had shattered the aircraft, the high inertial energy vertical and horizontal components of the resulting wreckage would quickly be absorbed by the water, remaining largely together in a collected mass, their individual weight and buoyancy then acting as a distribution filter, slowly separating heavier from lighter parts as they descended and were affected by whatever currents there were, creating the pattern observed in the AUV image, (as observed by others,
JD-EE in particular has described quite well above). I think a general conclusion may be made as to direction of flight. All parts descending through the same "water column" (roughly), would be affected in the same general manner.
And it doesn't seem as though some of the larger parts have, due to their shape, etc, "flown/glided" down (as some have observed I know), but rather may have "glided locally" and largely together, settling as described, by weight and buoyancy as a group.
Regardless of surface, the Nagoya accident shows quite clearly what happens to the fuselage in a high-vertical-speed impact - it collapses and, we may surmize, the substantial volume of air thus instantly compressed would escape through the breaks which would likely be at the mid-line of the fuselage as viewed on-end, with fractures at those fuselage sections we have seen before...behind the cockpit, just in front of and just behind the wing-box, and just ahead of the vertical/horizontal stabilizers and pressure bulkhead, (the section shown being manufactured in Machaca's superb photographs at
post #3170), all permitting large sections of the cabin to be ejected relatively cleanly, without more than glancing collisions with other parts, leaving them in the condition we see in the collected wreckage.
Chris, just spotted your note to Lonewolf...in my recollection of the system, that was a nice description of how it works. Bit different than the DC8...