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From: plains!umn-cs!LOCAL!thornley@uunet.UU.NET (David H. Thornley)
Newsgroups: sci.military
Subject: Re: _Furious_ and _Iowa_ Was: Re: Battleship Nelson
Message-ID: <1990Aug28.042707.29047@cbnews.att.com>
Date: 28 Aug 90 04:27:07 GMT
References: <1990Jul25.004713.6986@cbnews.att.com> <1990Aug3.031249.20275@cbnews.att.com> <1990Aug9.015753.8169@cbnews.att.com> <1990Aug15.032745.27552@cbnews.att.com>
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From: plains!umn-cs!LOCAL!thornley@uunet.UU.NET (David H. Thornley)
In article <1990Aug15.032745.27552@cbnews.att.com> phil@zorch.SF-Bay.ORG (Phil Gustafson) writes:
>
>
>From: phil@zorch.SF-Bay.ORG (Phil Gustafson)
>In article <1990Aug9.015753.8169@cbnews.att.com> paul@batserver.cs.uq.oz.au (Paul Bailes) writes:
>>
>>	I think the Lions to be better value for money than the US Iowas:
>>	these battlecruisers (only 12" belts!) surely would have been at risk
>>	at close range - was the USN relying on their speed to keep far away?
>>Paul Bailes
>
>You and the old-line admirals of the 30's.  The _Iowa_ class violated a
>cardinal rule of battleship design in that they had almost no immune
>zone (23,600 to 27,400 yards) against their own weapons.  But they
>really weren't designed to stand up against a battle line -- they were
>planned to protect carriers from Japanese heavy cruisers and _Kongo_
>class battlecruisers.

Not really, they were designed as *fast* versions of the earlier battleships,
and were armored as battleships.  They were originally designed with an
immune zone of 18,000-30,000 yards against the 16"/45 (on the North Carolina
and South Dakota classes) and 21,700-32,100 yards against the 16"/50 they
carried themselves, and these are respectable immune zones.

The problem came when Ordnance developed the 2,700-lb shell for the new
guns, and suddenly the immune zones shrunk to 20,200-25,500 yards and
23,600-27,400 yards respectively.  In 1940, a sketch design of a ship
with a good immune zone against the new shells (and 5"/54 secondary
armament) came in at 51,500 tons and 28 knots.  The earlier battleships
had their immune zones also suffer; the S.D. class wound up with 20,500-
26,400 against their own guns (but the turret faces had to be supplemented,
since they could be penetrated out to 41,700 yards!) and the North Carolinas
were weaker still (having been designed for 14" guns).

It was not until the Montana class that U.S. BBs were designed to resist the
new shells, and of course those were never even started.

David Thornley