BOAC: Hydrodynamics work pretty much as aerodynamics at low speeds. A wing will produce a force of some sort.
BOAC I agree with you, the main difference between falling in air and in water is the specific whight 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
a very long time to turtle around
grity
p.s. again my question: what else did wie see on the underwater picture with the wing??
http://www.pprune.org/6352263-post3037.html