Originally posted by grity ...
the main difference between falling in air and in water is the specific weight of the medium, and it goes into the speed formula with his square root.....
water is 1000 times heavier than air, sqrt 1000= 31.6
so if it was fallen through the air with 75 m/s it will sink under water with a dimension of 75/31,6=2,4 m/s and so it will need around 4000/2,4=1666 sec (half an hour!) to reach the sea bottom
Technically true, but Archimedes' principle gets involved at the air/water interface. As I have pointed out in previous posts there are reciprocal buoyancy moments that interact at the time of impact, and even during the course of a break-up, there will be items that are compressible and others that aren't. For instance, the moment the originally intact hull is breached, the total buoyancy moment is lost, but within the hull there are numerous items that retain buoyancy - not to forget the fuel.
This aircraft has broken up at the surface after a high AoA and high rate of descent impact. Some items, e.g. engines will part company with the pylon mounts immediately due to the obvious disparity in their mass and volume when compared to the intact area of the wing to which they were attached. The engines actual impact velocity will be further reduced by the difference between the acceleration force that stops the wing and the force that shears their mountings.
All that means is that it is not a simple matter to determine at what rate an object will sink, as it will depend on many factors that make up a homogenous mass. Some items with profiles that present "slippery" surfaces in a fluid dynamics sense may take trajectories that their shape permits, while other stuff will just "sink".
As has previously been said, there will be no rush to the bottom, as increasing pressure equals increasing surface friction.
There will be a relationship to where items are located on the bottom and the time that it took them to get there. A small subsurface current heading west will be responsible for some of the east/west distribution.
In the case of the HMS "Ark Royal", it would appear that it broke in two on the surface, and the two separate halves then had differently distributed centers of gravity and fluid dynamics allowed them to head to the bottom on differing trajectories. Remember that a ship that no longer floats will still have intact water-tight compartments that will impact on its center of buoyancy and cause its attitude to change during the sinking process. Hence a possible reason the two halves were found so far apart.