Re: Yamato Last Sortie - Atomic Bomb "What-if"

"Scott M. Kozel" <kozelsm@xxxxxxxxxxx> ha scritto

> so I daresay that a sea-surface burst of a Fat Man atomic
> bomb would have a much greater effect than what you seem
> to surmise, as to displacing a tremendous amount of sea
> water and having a major underwater shockwave effect.

I have here an old (1973) Italian Air Force manual about
air weapons. With reference to nukes, it says that a 20kt
*_underwater_* (-20m) explosion:

"Will create, after two seconds, a hollow column of water
1,500m high, with 800m external diameter and 200m thick
sides" (the internal 400m is pure gas, rising at Mach 2.
Presumibly anything built by the man and floating inside
this column will be terminated forever).

"At the same time, after 2 seconds, the [*_air_*] shock wave
will have reached 3,200m from point zero." There are not
definite values about the pressure, but with a speed of
Mach 5 it seems pretty hard.

After a [short] while the water column will reduce its size:
after 20 seconds it will have a height of 250m at 300m from
Point Zero, the water falling to the surface and creating a
tsunami wave with an height (at this time) of 17m at 500m
from Point Zero.

After 60 seconds the seawave will have reached a distance
of 1,500m, with a height of 5-6m (so, speed of 50mph). In
the air, at the same distance, there will be a ring of water
vapour 300m high and with a radioactivity in the region of
50.000 roentgen per hour [unable to translate this into a
comprehensible figure, but the book seems to imply that
this is a very bad thing to experience].

After 150 secs the sea wave will have reached a distance
of 3,600m, 3m high, "and from this moment it will no more
constituite a hazard." The vapour ring will have a 2,400m
radius, 500m high, "and from it a thick radioactive rain will
continuosly fall."

The effects for an explosion *_on the surface_* are a bit
different, and somewhat milder upon structures (but the
book details only _land_ explosion over the surface).

About the what-if we are discussing, it's likely that the
Americans would have preferred an atmospheric explosion,
since they had had no underwater test and so very probably
they did not realize its power.


--

Davide

"Solo se la vostra visione va oltre quella del vostro maestro,
siete adatti per ricevere e tramandare la trasmissione."

(Massima Zen)


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