[sci.military] Ship armor

mcdaniel@uicsrd.csrd.uiuc.edu (Tim McDaniel) (04/26/89)

From: mcdaniel@uicsrd.csrd.uiuc.edu (Tim McDaniel)



From: henry@zoo.toronto.edu (Henry Spencer)
> There is never enough ... weight available in a warship.  Useful
> amounts of armor are very heavy.  Even the Iowas aren't armored
> everywhere ...
> Armor fell out of fashion after WWII, since it wasn't useful against
> nuclear weapons.  Ship designers were happy to have the extra weight
> for other things, and haven't been enthusiastic about reintroducing
> armor.

From: rupp@cod.nosc.mil (William L. Rupp)
> the four Iowa class ships are a bargain, and for the following
> reasons:
> They are very, very, heavily armored, which is *extremely* important
> in these days of cheap missiles that can disable a very expensive,
> but unarmored, modern warship.

Perhaps I am simply ignorant, but Mr. Rupp's argument seems more
reasonable.  Please correct any errors of fact or misapprehensions.

- I have my doubts about the probability of nuclear war remaining
contained to the naval arena.  Consider that such a war would hurt the
U.S.'s strategic position far more than the Soviet's, because we are
separated by oceans from our major allies.  If nuclear weapons aren't
restricted to naval war, it doesn't greatly matter what we do with
ship armor.

- Our naval conflicts haven't involved other nuclear powers.

- Missiles seem to be today's general weapon-of-choice, unlike the
shells, torpedos, and mines of previous years.  However, conventional
missiles tend to have low explosive yields, so less armor should be
necessary.  I've heard that "six hits from any of today's missiles in
the same place still won't pierce battleship armor".  This is unlikely
(armor isn't uniformly protective) but indicative.

- Armor is "expensive" in weight, leading to a deeper draft, thus less
fuel efficiency and less maximum speed (any other costs?).  Anti-missile
defences, however, are expensive in research, development, and
production ($).  Furthermore, as Sheffield and Stark found, the
missile defence has to be turned *on* and has to be *working* --
armor's always there, even when surprised.  (See the occasional doubts
about the effectiveness of the Phalanx.)

- Armor gives at least some protection against missiles, torpedos,
shells, bombs, *and* mines.  Active protection can be used: making
sure that hostile units never get to *use* missiles, etc., or stopping
those that get used.  However, some will still get through.

- It's possible to go too far in reducing weight.  Does non-powdered
aluminum burn if given enough heat (i.e. an Exocet engine)?  If not,
ignore this.  If so, building destroyers out of aluminum seems silly.

- We now know how to made lighter armor, albeit with greater expense.

How much speed would be lost in armoring a cruiser, then?  (Recall
that the maximum speed of USS Iowa is a respectable 33 knots.)  In a
real-war mix of operations, how important is that extra speed?  How
important is the capability to absorb more punishment?

Some World War II German tank commanders said that they would have
preferred lighter, faster tanks, mobility being more important (was
this in Liddell-Hart?)  How well does this generalize to ships?  In
the relatively static venues of the Falklands and the Persian Gulf,
armor would seem more important.

Again, I welcome corrections, amplification, rebuttal, et cetera.
Even "shut up, you don't know what you're talking about." :-)

--

             Tim, the Bizarre and Oddly-Dressed Enchanter

Center for      |||  Internet, BITNET:  mcdaniel@uicsrd.csrd.uiuc.edu
Supercomputing  |||  UUCP:     {uunet,convex,pur-ee}!uiucuxc!uicsrd!mcdaniel
Research and    |||  ARPANET:  mcdaniel%uicsrd@uxc.cso.uiuc.edu
Development,    |||  CSNET:    mcdaniel%uicsrd@uiuc.csnet
U of Illinois   |||  DECnet:   GARCON::"mcdaniel@uicsrd.csrd.uiuc.edu"

military@att.att.com (Bill Thacker) (04/26/89)

From: military@att.att.com (Bill Thacker)


Tim McDaniel writes:

>- Missiles seem to be today's general weapon-of-choice, unlike the
>shells, torpedos, and mines of previous years.  However, conventional
>missiles tend to have low explosive yields, so less armor should be
>necessary.  I've heard that "six hits from any of today's missiles in
>the same place still won't pierce battleship armor".  This is unlikely
>(armor isn't uniformly protective) but indicative.

I don't doubt this statement at all; if one explosion won't cave in the
armor, it's unlikely that a dozen will.

Of course, as Henry Spencer pointed out, the Iowas aren't armored 
everywhere;  the bows and stern, for example, are unarmored, and
could be demolished by missiles; meaning that the junior officers
cabins will be gone.  Even with fully-flooded bow and stern,
though, the ship should still be able to float, and probably even fight
and maneuver.  Essentially, you can't sink them without penetrating the
armor belt (which runs from #1 turret to #3 (stern) turret) or torpedoing
them.

>- Armor is "expensive" in weight, leading to a deeper draft, thus less
>fuel efficiency and less maximum speed (any other costs?).  

This is essentially it.  In WWII and before, the "big three" items
in warship design were armor, propulsion, and armament; a gain in one
could only be achieved to the detriment of the others, unless you
could increase displacement (which was limited by docking considerations
and, at the time, the Panama Canal).

Of course, you also need space (therefore, weight) for fuel, provisions,
ammo, crew, electronics, etc, etc.

>- Armor gives at least some protection against missiles, torpedos,
>shells, bombs, *and* mines.  Active protection can be used: making

Armor doesn't add much to torpedo or mine defense.  Basically, it
takes a *lot* of armor to resist an underwater explosion; more than
can be economically carried over such a large area.

Typically, the approach is to instead provide several torpedo bulkheads,
with void space between, to absorb and abate the blast of the explosion;
the innermost bulkhead is typically lightly armored to resist steel
splinters, thereby maintaining watertight integrity.  Similarly, double-
or triple-bottoms are used to resist mines.  (The Italians employed the
complicated Pugliese system, which is another story altogether).

Details of Iowa's underwater protection are very vague, but it seems
likely that four torpedo bulkheads were provided, the outer two filled 
with fuel oil or water.  A triple bottom was also fitted.  This system
was used on the South Dakotas which immediately proceded them, and 
planned for the Montanas to follow.

>How much speed would be lost in armoring a cruiser, then?  (Recall
>that the maximum speed of USS Iowa is a respectable 33 knots.)  In a
>real-war mix of operations, how important is that extra speed?  How
>important is the capability to absorb more punishment?

I don't know what speed modern cruisers can make, but in WWII, virtually
every nation had a 32-33 knot heavy cruiser, with good armor; some made
as high as 35 knots.  I'm guessing an important tradeoff is magazine
space;  I'd guess that missiles require more magazine space than
powder and shells; this extra space would have to be armored, 
increasing weight and thus draught, thereby requiring more power to
maintain the speed, meaning more volume, thus more armor, ...

Still, I wonder how much armor would be necessary to defeat the current
and projected antiship missiles...

>Some World War II German tank commanders said that they would have
>preferred lighter, faster tanks, mobility being more important (was
>this in Liddell-Hart?) How well does this generalize to ships?  In
>the relatively static venues of the Falklands and the Persian Gulf,
>armor would seem more important.

Lord Fisher was a big proponent of speed-vs-armor in WWI Britain.  He felt
that speed could replace armor, to an extent; a faster ship was harder to
hit.  He fathered the concept of the battlecruiser, lightly armored but
carrying battleship guns, faster than battleships (and as fast as
cruisers).  They could outrun anything they couldn't fight, and outfight
anything they couldn't outrun. 

Germany, too, adopted battlecruisers; but they chose to use a lighter
armament to allow higher speed, keeping armor protection high.

In the battle of Jutland (WWI's decisive naval battle), 3 British
battlecruiser (Invincible, Indefatigable, and Queen Mary) received hits
from their German counterparts (Lutzow, Derfflinger, Von der Tann, and
Seydlitz) and blew up with massive loss of life.  The German ships fared
better;  Seydlitz, for example, took some 21 heavy shell hits and
torpedoes, suffered two turrets burned out, shipped 5300 tons of water,
and still returned home under her own power, to be repaired and returned
to service.  Derfflinger took slightly more moderate damage, while Lutzow
had to be scuttled while returning home, having taken the same number of
hits.

Events clearly indicated that speed did not make up for protection.
I can't help but think that this lesson is still quite appropriate
in the modern battlefield where missiles can be fired from over the horizon
and accurately seek out even an evasive target; and one such hit can 
disable the target (at least, render it ineffective for combat).


-  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - 
Bill Thacker      moderator, sci.military      military@att.att.com
		      (614) 860-5294
"War is a matter of vital importance to the State; the province of life
or death; the road to survival or ruin. It is mandatory that it be 
thoroughly studied."   -  Sun Tzu

djm@etive.edinburgh.ac.uk (D Murphy) (04/27/89)

From: D Murphy <djm@etive.edinburgh.ac.uk>

In article <5929@cbnews.ATT.COM> military@att.att.com (Bill Thacker) writes:
>
>
>In the battle of Jutland (WWI's decisive naval battle), 3 British
>battlecruiser (Invincible, Indefatigable, and Queen Mary) received hits
>from their German counterparts (Lutzow, Derfflinger, Von der Tann, and
>Seydlitz) and blew up with massive loss of life.  The German ships fared
>better;  Seydlitz, for example, took some 21 heavy shell hits and
>torpedoes, suffered two turrets burned out, shipped 5300 tons of water,
>and still returned home under her own power, to be repaired and returned
>to service.  Derfflinger took slightly more moderate damage, while Lutzow
>had to be scuttled while returning home, having taken the same number of
>hits.
>
>Events clearly indicated that speed did not make up for protection.
>I can't help but think that this lesson is still quite appropriate
>in the modern battlefield where missiles can be fired from over the horizon
>and accurately seek out even an evasive target; and one such hit can 
>disable the target (at least, render it ineffective for combat).
>
 
Yes, but I recall that there were problems with the storage of munitions
in the magazines (according to a TV documentary in the UK a few years ago).
Apparently what happened was that the propellant was kept in bags which
had the bag `primer' covered by a paper strip in storage - this was supposed
to be removed during loading so that the thing would work when it was fired.
To increase reload speed some of these tags had been removed - creating a
severe fire hazard in the magazines and causing some of the ships to blow
up after receiving minor hits - hence "There's something wrong with our
bloody ships today".

[mod.note:  True.  Events at Jutland led to major redesign of the
battlecruisers then building, and of warships in general, in the British
fleet. In  particular, new antiflash systems were installed to prevent
turret fires from quickly spreading to the magazines.

Still, HMS Hood, completed well after Jutland, suffered the same 
fate.  - Bill ]


In the battle of the Falkland Islands (the WWI one) British battlecruisers
caught (I think) 3 German cruisers (they'd been caught away from home at the
start of the war and were engaged on commerce raiding) and blew them out
of the water before the Germans could fire back.

[mod.note:  Never a fair fight, of course... and I believe the Germans
*did* fire back;  Breyer lists Invincible as taking some 23 hits in that
action. Of course, the small German guns couldn't penetrate even battlecruiser
armor at long ranges.  - Bill ]

Murff....

JANET: djm@uk.ac.ed.etive      Internet: djm%ed.etive@nsfnet-relay.ac.uk   
       Murff@uk.ac.ed.emas-a             Murff%ed.emas-a@nsfnet-relay.ac.uk
       trinity@uk.ac.ed.cs.tardis        trinity%ed.cs.tardis@nsfnet-relay.ac.uk


D.J. Murphy
Chemistry Dept.
Univ. of Edinburgh

  "I don't want to achieve immortality through my work,
    I want to achieve it through not dying."

                                            Woody Allen

pschmidt@bbn.com (Peter H. Schmidt) (04/27/89)

From: pschmidt@bbn.com (Peter H. Schmidt)

How about reactive armor for ships?  Advantages: light, relatively inexpensive
(compared to re-armoring with steel), removable, and upgradable (easy to
install a new generation of armor to defeat a new missile).

Disadvantages, anyone?

--Peter




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Peter H. Schmidt	   | All sweeping generalizations are invalid.
BBN Advanced Computers Inc.| The one intolerable is intolerance.
10 Fawcett St.		   | Loving thy neighbor usually isn't worth the 
Cambridge, MA 02238	   | 	effort.
(617) 873-4311		   | (I speak only for myself.)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

livesey@apple.com (John Livesey) (04/28/89)

From: goofy!Apple.COM!livesey@apple.com (John Livesey)

The moderator writes:

>[mod.note:  True.  Events at Jutland led to major redesign of the
>battlecruisers then building, and of warships in general, in the British
>fleet. In  particular, new antiflash systems were installed to prevent
>turret fires from quickly spreading to the magazines.

Actually, it goes back further than that.   At the battle of Dogger
Bank, a German Battle Cruiser suffered a turret fire from similar
causes, and by the time of Jutland, the German Navy had made its
powder-handling procedures safer.   The British had not suffered a
similar incident at Dogger Bank, and had not learned the same lessons;
they learned them at Jutland.

>Still, HMS Hood, completed well after Jutland, suffered the same 
>fate.  - Bill ]

No-one really knows what happened to the Hood; there were less than ten
survivors.   There are three popular theories.   One that deck-mounted
rockets ignited, causing an explosion.   One that a turret hit caused a
magazine explosion.    One that a shell hit short, turned almost
horizontal, and penetrated below the armour belt as the Hood heeled.

The danger of such incidents was understood.  The Hood was building at
the time of Jutland, and was suspended for a redesign that led to
heavier armouring.   However, by the time that the Hood was sunk, it
was over twenty years old, and both technology and tactics had changed
enough to render the original design invalid; about as significant as,
say, sinking the Balgrano in the Falklands, and not very instructive
about contemporary ship design.

jon.

henry@zoo.toronto.edu (Henry Spencer) (04/28/89)

From: henry@zoo.toronto.edu (Henry Spencer)
>In the battle of Jutland (WWI's decisive naval battle), 3 British
>battlecruiser (Invincible, Indefatigable, and Queen Mary) received hits
>from their German counterparts (Lutzow, Derfflinger, Von der Tann, and
>Seydlitz) and blew up with massive loss of life.  The German ships fared
>better...
>Events clearly indicated that speed did not make up for protection.

In fairness, there were complicating factors at Jutland that make a fully
unbiased comparison difficult.  In particular, the propellant compositions
differed, and this had important effects:  German "powder" burned viciously
when ignited, and tended to wipe out turret crews, but the British stuff
exploded and destroyed entire ships.  Switch propellant compositions and
the results might have been more even.

                                     Henry Spencer at U of Toronto Zoology
                                 uunet!attcan!utzoo!henry henry@zoo.toronto.edu

gahooten@ames.arc.nasa.gov (Greg A. Hooten) (04/29/89)

From: gahooten@ames.arc.nasa.gov (Greg A. Hooten)

In article <6030@cbnews.ATT.COM> goofy!Apple.COM!livesey@apple.com (John Livesey) writes:
>
>There are three popular theories.   One that deck-mounted
>rockets ignited, causing an explosion.   One that a turret hit caused a
>magazine explosion.    One that a shell hit short, turned almost
>horizontal, and penetrated below the armour belt as the Hood heeled.
>
There is a fourth theory that I read some 12 years ago when a
new magazine Sea Classics (ala Air Classics) came out.  The
author believed that the Hood was sunk by the escorting
cruiser to the Biz (Prinz Eugean?).  The theory went like
this.  The Prinz Eugean's guns (8"? Sorry about the memory
loss, it was 12 years ago.) were at there maximum range while
the Biz was firing at long but not ultra long range.  The 
arc of the smaller shells would have plunged the shell almost
strait down while the Biz' shell would have been on a
shallower angle.  The steep plunge of the smaller shells could
have penetrated between the two stacks on the hood into the
depths of the ship through the relitively unarmoured decking.
I believe that there was mention of weak armor at this place
in the ship, that corresponded with the upward explosion of
the ship before it broke in half.  

The article goes on to say that this may or may not have been
known by the Germans at the time, but porbably would have been
hidden if it was known.  Having a cruiser sind a BC (how I
have always seen Battle Cruisers designated) sunk by a cruiser
while the Biz bagged nothing would have been bad politics at
the time.  

My memory fades.  Please correct any and all.

GAH!



[mod.note: This theory was popular for awhile, but has been shown 
incorrect.  Prinz Eugen's fire did start a large fire on Hood's boat
deck (funnel area), but had shifted to engage Prince of Wales before
Hood exploded.  There had been too much difficulty observing the
fall of Eugen's shots on Hood, what with Bismarck's gunnery concentrated
there. 

In Warship International No.2, 1987, W.J. Jurens engages in a fascinating
technical discussion of Hood's loss ("The Loss of HMS Hood - A
Re-Examination", p 122).  He considers the numerous theories of Hood's
demise.  He considers the shell ballistics, and precise angles of impact,
given the relative bearings of incoming shells, to determine the
likelihood of penetrations and their locations.  He quickly dismisses
Prinz Eugen, base on both the testimony of her captain and her
utter inability to penetrate the magazines of Hood at the range of combat.

Concluding his technical analysis, Jurens suggests that a 15" shell from
Bismarck struck Hood near her main mast, plunging into after engine room
and exploding in or near her 4" secondary magazine just aft of that
compartment; alternately, the shell could have passed through Hood's
upper armor belt to reach the same location.  Penetration was facilitated
by the fact that Hood was engaged in a 20-degree turn away from Bismarck,
attempting to open the firing arcs of her stern turrets; this cause her
to heel somewhat toward Bismarck, exposing more of her deck armor and
decreasing the angle of impact thereupon.

The explosion of the shell ignited the powder in that 4" magazine, 
which burned rapidly, creating an enormous overpressure which burst 
into the engineering space (visual evidence of which was reported prior
to Hood's explosion).  The secondary magazine contained some 18.5 tons of
cordite.  While the expansion into the engine room temporarily relieved
the pressure it soon built up again sufficiently to force its way rearwards
into X magazine, which contained an additional 49 tons of cordite, then
chain-reacted to Y magazine, adding another 45 tons to the tally.  The
immense and rapidly-building pressure blew Hood apart.

Of course, this is just one theory, but it is the most modern and, IMHO,
most beleiveable.  I *highly* reccommend Mr. Juren's article; it not only
describes this important battle in detail, but it's a good primer in
battleship design and gunnery considerations.  - Bill ]

maniac%garnet.Berkeley.EDU@ucbvax.Berkeley.EDU (George W. Herbert) (04/29/89)

From: maniac%garnet.Berkeley.EDU@ucbvax.Berkeley.EDU (George W. Herbert)

In article <5987@cbnews.ATT.COM> pschmidt@bbn.com (Peter H. Schmidt) writes:
>How about reactive armor for ships?  Advantages: light, relatively inexpensive
>(compared to re-armoring with steel), removable, and upgradable (easy to
>install a new generation of armor to defeat a new missile).
>Disadvantages, anyone?

Aagh! Yes, there are disatvantages.
Reactive armour operates by firing a Milder explosion outwards from the casing
to disrupt the jet of a shaped antitank warhead.  It requires that there be
a: a shaped charge penetrator-type attack and
b: a hefty amout of backing armour, cuz the 'milder' explosion is not so mild
	overall.  for instance: don't stand next to a tank when a reacive
	armour box blows.  it's fatal.

The antiship warheads are not shaped charge and ships generally don't have 
enough of a hull backing to prevent collateral damage.

george william herbert 
maniac@garnet.berkeley.edu

wbralick@BLACKBIRD.AFIT.AF.MIL (Will Bralick) (05/01/89)

From: wbralick@BLACKBIRD.AFIT.AF.MIL (Will Bralick)

In article <5929@cbnews.ATT.COM> military@att.att.com (Bill Thacker) writes:
>
>Of course, as Henry Spencer pointed out, the Iowas aren't armored 
>everywhere;  the bows and stern, for example, are unarmored, and

Doesn't this have to do with the (a) the structure of the bow (long and
narrow hence more likely to deflect incoming munitions) and (b) the
method of engaging the enemy by turning one's side to the enemy
to bring the most firepower to bear (in a broadside)?  Thus it is the 
_side_ of the vessel which (a) presents a broad, open, flat expanse 
of metal for weapons to smack into and (b) is most likely to be facing 
an enemy during an engagement. 

[mod.note: Let's not misunderstand each other.  I'm referring to the
sides of the bow and stern.  The mail belt, and armored decks, run from
the forward magazines to the aft magazines; basically, a little
past the endmost turrets.  These are capped, fore and aft, by armored 
bulkheads. 

The entire bow and stern structures are unarmored (save for armored boxes
around the rudder and shafts in the stern).  Armor is sacrificed here
simply because it would be far too heavy; it would roughly double the
weight of armor carried by the ships which, according to Breyer, is 
already some 41% of the Iowa's displacement. - Bill ]

>could be demolished by missiles; meaning that the junior officers
>cabins will be gone.  Even with fully-flooded bow and stern,
>though, the ship should still be able to float, and probably even fight
>and maneuver.

How could one _possibly_ manuever, much less fight, without junior 
officers??  :-) :-)
-- 
Will Bralick  ( O-3 )                 |  ... when princes think more of
     wbralick@blackbird.afit.af.mil   |  luxury than of arms, they lose
     wbralick@afit-ab.arpa            |  their state.
with disclaimer;  use disclaimer;     |             - Niccolo Machiavelli

henry@zoo.toronto.edu (Henry Spencer) (05/01/89)

From: henry@zoo.toronto.edu (Henry Spencer)
>In the battle of the Falkland Islands (the WWI one) British battlecruisers
>caught (I think) 3 German cruisers (they'd been caught away from home at the
>start of the war and were engaged on commerce raiding) and blew them out
>of the water before the Germans could fire back.
>
>[mod.note:  Never a fair fight, of course...

This one definitely wasn't.  Don't take the Battle of the Falklands as
indicative of what then-state-of-the-art warships would do against each other.
The German unit was their Far Eastern squadron, a handful of small, old
ships well below then-current first-line standards.  It had managed to
beat up on an even smaller and older British squadron at the Battle of
Coronel.  That caused enough of a fuss that the British Admiralty sent
two of their latest and best battle cruisers down to settle the issue.

It turned out to be a textbook example of the value of long-range guns
on fast ships against inferior opponents:  the British ships used their
superior speed to stand off at a range where the German guns couldn't
hit effectively but the British ones could, and pounded the German ships
into scrap at leisure.  Against more modern German ships -- faster, with
bigger guns and heavier armor -- it wouldn't have been so one-sided.
All the actual result proved was the obvious:  much heavier guns on much
faster ships are an unbeatable combination.

                                     Henry Spencer at U of Toronto Zoology
                                 uunet!attcan!utzoo!henry henry@zoo.toronto.edu

kiravuo@kampi.hut.fi (Timo Kiravuo) (05/03/89)

From: kiravuo@kampi.hut.fi (Timo Kiravuo)
In article <6095@cbnews.ATT.COM> wbralick@BLACKBIRD.AFIT.AF.MIL (Will Bralick) writes:

>                                                    ... Thus it is the 
> _side_ of the vessel which (a) presents a broad, open, flat expanse 
> of metal for weapons to smack into ...

That depends on the shooting range.  When I served at the Finnish
Coastal Artillery, we were taught that it is easier to hit a ship
that is facing the guns.  This is becouse of the elliptical
pattern of the hits.  When the range is something like 5 - 20 km,
the shells are falling almost vertical, so there is not very much
sweep, like what you would get with a flatter trajectory, and for
a sea target you still have to get a direct hit. If you miss it
by a meter, you could as well miss it by a mile (unless it is a
very small target, which can capsize).

If the range is very short, then a ship being sideways is a
better target, becouse the shell sweeps the area of the target.
(This is elementary ballistics, I suppouse)

As to the age of guns, there are still some old Russian barrels
in service. They have the old crowned seals at the breech end
with Russian writing and all. The guns itself have been
modernized, but since there is nothing wrong with the barrels,
why not use them? Finland is a small country, and we can't really
afford to spend money like some big countries do (like those old
British colonies in west, what were they now called ;-)

Please forgive me that I don't know all the correct English
military terms, I am a Finn, you know.

--
Timo  Kiravuo                           tel.  90-451 4328
Helsinki  University  of  Technology,    Computing Center
kiravuo@hut.fi   kiravuo@fingate.bitnet   opmvax::kiravuo

asulaima@udenva.cair.du.edu (SULAIMAN) (05/03/89)

From: asulaima@udenva.cair.du.edu (SULAIMAN)

>
>>- Armor is "expensive" in weight, leading to a deeper draft, thus less
>>fuel efficiency and less maximum speed (any other costs?).  
>
>This is essentially it.  In WWII and before, the "big three" items
>in warship design were armor, propulsion, and armament; a gain in one
>could only be achieved to the detriment of the others, unless you
>could increase displacement (which was limited by docking considerations
>and, at the time, the Panama Canal).
>
>
>Armor doesn't add much to torpedo or mine defense.  Basically, it
>takes a *lot* of armor to resist an underwater explosion; more than
>can be economically carried over such a large area.

While current common missiles (Harpoon,Exocet etc) may not have nuch armor
penetration. Until recently they have not needed it. Except for the CVs
and the new Iowas and the Sov Kirov things were not armored. If u do hit
a CV theory went the chances of damaging fuel etc on flight damage are
so good that it would take a CV out of action for a while anyway. 
The advantage missiles have had over guns is mostly Range and Accuracy.
You need toi fire just one missile, no ranging fire done and there is a good
chance that it will hit its intended target. Any hit is bad for ships withg
their delicate radar and sensor suites. The pop-ups though easier to 
knock out with missile defenses play havoc with control centres and
radars. Iowa's armor gives it incredible protection but getting hit is
still not pleasant and I'm quite sure that the Iowa's captain really would
want to test his armor while trying to close within gun range of Sov
ships. Missiles as a rule have required more space and magazine capacity
more electronics to perform their mission. Since maneuverability(not speed!!)
is considered paramount in evading missiles ships had to be light. Speed 
was necessary to avoid contacts and outrun subs. In the end armor was the thing
that had to go. In general u want to point the bow or the stern at the missile 
to reduce your radar signature. Question being that while Iowa's are fast and
armored are they maneuverable or do they turn like bath tubs?
Missiles can be decoyed by chaff/flares etc but as in Jutland ships could
hide themselves from guns under smoke sometimes unintentional smoke from
the guns themselves. I think what has to be clearly understood is that
the big thing about Iowa is their armor and only that. Their guns/size/speed
is only of secondary importance in modern naval combat. They need air
superiority to provide shore cover and ships with anti-missile defenses 
to protect them from enemy SSMs. Their speed while good is not awesome and
they are not particularly maneuverable given their size. Their size is a 
handicap in a world where missiles lock-on based on size of radar return
Iowa has a BIG radar signature. Their armor protects but their size attracts
the enemy and the missiles, Iowas cannot avoid combat if given and as we
can only speculate oin nature of future conflicts I don't think that being
the center of attention is so good. The CV can avoid using planes but as I
understand it the Iowas get their own Battle group sans air cover!
I'm sure the Marines would love the Iowa's shore bombardment ability. I'm
also sure they would prefer to be under CV CAP so they can get where they
are supposed to...

	Ameer Z. Sulaiman.

esco@tank.uchicago.edu (ross paul weiner) (05/05/89)

From: "ross paul weiner" <esco@tank.uchicago.edu>
In article <6196@cbnews.ATT.COM> you write:
>From: asulaima@udenva.cair.du.edu (SULAIMAN)

	much deleted

>to reduce your radar signature. Question being that while Iowa's are fast and
>armored are they maneuverable or do they turn like bath tubs?

Four screws and twin rudders should make for a very manueverable ship,
in the open waters and at a Standard bell or better.  I would rather drive a
BB than a single shaft FF, for that matter I would much rather try to
moor a BB than a FF if the wind was offsetting.

>they are not particularly maneuverable given their size. Their size is a 
>handicap in a world where missiles lock-on based on size of radar return
>Iowa has a BIG radar signature. Their armor protects but their size attracts

Au contraire mon frere.  The BB is just a big gunboat.  It sits rather low in 
the water to look at.  I forget what she looks like on a scope but it must be 
smaller than a CV or an amphib or a big merchant.

>	Ameer Z. Sulaiman.


-- 

	Ross P. Weiner		Dandy Dirks Discount Disclaimers
	esco@tank.uchicago.edu	 "You can't sue me, I'm broke!"

[mod.note:  I wouldn't think the Iowa would be particularly maneuverable,
given her great length and length-to-beam ratio; she's tailored more for
efficient speed.   However, she does a few things very well.  I recall an
issue of Proceedings some months ago which featured a short article by one
of her junior officers.  He mentioned her incredible stopping ability.

Basically, the captain orders full reverse, and "closes the barn doors";
the two rudders are operated independently, both turning outward so
that the tails funnel together.  This creates a tremendous drag; the
officer claimed that if you throw a marker off the bow at the start of the
maneuver, the ship will stop before the marker passes the stern !  He
likened the effect to standing on a flatbed semi trailer when the brakes
are locked up, noting that the maneuver is never done while mess is being
served.  - Bill ]

livesey@apple.com (John Livesey) (05/06/89)

From: goofy!Apple.COM!livesey@apple.com (John Livesey)

In article <6095@cbnews.ATT.COM> wbralick@BLACKBIRD.AFIT.AF.MIL (Will Bralick) writes:
>
>>Of course, as Henry Spencer pointed out, the Iowas aren't armored 
>>everywhere;  the bows and stern, for example, are unarmored, and
>
>Doesn't this have to do with the (a) the structure of the bow (long and
>narrow hence more likely to deflect incoming munitions) and (b) the
>method of engaging the enemy by turning one's side to the enemy
>to bring the most firepower to bear (in a broadside)?  Thus it is the 
>_side_ of the vessel which (a) presents a broad, open, flat expanse 
>of metal for weapons to smack into and (b) is most likely to be facing 
>an enemy during an engagement. 

During the battle of the Denmark Strait, the Bismark took a hit through
the unarmoured bow which had no effect on its gunnery, but which
pierced a fuel tank.   This left a track of fuel on the water that
search planes could follow, and also made about 1000 out of eight
thousand tonnes of fuel unusable.   As a result, the Bismark later had
a serious fuel shortage, which caused it to make for Brest by a direct
and rather predictable route.

jon.

[mod.note: I seem to recall, too, that the Graf Spee was forced to
retire to Montevideo mostly because of a bow hit which damaged her
fuel filter;  she was Diesel powered.  Unconfirmed data, though.
- Bill ]

livesey@apple.com (John Livesey) (05/06/89)

From: goofy!Apple.COM!livesey@apple.com (John Livesey)

In article <6069@cbnews.ATT.COM> gahooten@ames.arc.nasa.gov (Greg A. Hooten) writes:
>
>	[a bunch of interesting stuff about the Hood and the
>	Bismark]

Most of the discussion about the Bismark centres around the materiel
issues.   In some ways this is natural, since it's not every day that a
famous, if antique, ship is blown up.  However, I find that the
strategic issues are just as interesting.

In 1918 the German Navy was confiscated by the Allies.   Starting from
scratch, the German Republic, and later Hitler, rebuilt their surface
fleet in a novel way.    Finessing the issue of rebuilding an
all-purpose surface Navy, they started with three heavily armoured
cruisers, the Graf Spees (often called pocket battleships) which were
intended for commerce interdiction, an activity which requires an
extensive network of supply ships, and warships which are either fast
enough to evade cruisers, or strong enough to defeat them.  Then they
bult a class of two small battleships, the Scharnhorsts.  Finally, they
started two heavy battleships, the Bismarks.

It turned out in practice that the pocket battleships were neither fast
enough to outrun British cruisers, nor strong enough to defeat pairs of
them.  So single Graf Spees could not be risked in the Oceans.  The
Scharnhorsts were not fast enough to outrun the WWI era battle cruisers
or the British George V fast battleships, and not strong enough to take
on even WWI battleships, and when they encountered either of them (the
Norway campaign and North Cape) they retreated or were sunk.  That left
only the Bismarks, because when the war began, work on surface ships
was halted in favour of submarines.

So the Navy had a choice; either use the Bismarks for commerce
interdiction as they were completed, and risk losing them one by one,
or suspend surface naval operations until both Bismarks were
operational, at which point they would have a fairly serious surface
fleet; two Bismarks, two Scharnhorsts, and two or three fast heavy
cruisers.   A fleet like that could have entered the Atlantic, and
forced the RN to assemble task forces of four or five heavy ships,
instead of the pairs of ships that they actually did assemble.    If
the Germans got lucky, and perhaps surprised and overwhelmed one or two
of the old battleships that were used for convoy duties, they might
even have forced the RN to recall the Mediterranean Fleet, leaving the
Italian Navy in control, and making it much easier to supply North
Africa, capture Malta and the Suez canal, and cut the supply lines to
and from the Far East.

It has always seemed to me that the German Navy chose the strategy
that had the highest risk and the lowest payoff.   Comments?

jon.

welty@algol.crd.ge.com (richard welty) (05/12/89)

From: welty@algol.crd.ge.com (richard welty)
livesey@apple.com (John Livesey) writes:

*In article <6095@cbnews.ATT.COM> wbralick@BLACKBIRD.AFIT.AF.MIL (Will Bralick) writes:

*> someone writes:

*>>Of course, as Henry Spencer pointed out, the Iowas aren't armored 
*>>everywhere;  the bows and stern, for example, are unarmored, and

*>Doesn't this have to do with the (a) the structure of the bow (long and
*>narrow hence more likely to deflect incoming munitions) and (b) the
*>method of engaging the enemy by turning one's side to the enemy
*>to bring the most firepower to bear (in a broadside)?

it is more a consequence of the all-or-nothing protection
principle -- there are no vital systems in the extended bow;
the bow is long and narrow for better speed -- the ship can
still fight effectively even if the bow is damaged.

*During the battle of the Denmark Strait, the Bismark took a hit through
*the unarmoured bow which had no effect on its gunnery, but which
*pierced a fuel tank.

the bow armor was a serious concern in the Iowa class ships;
there is a transverse bulkhead just forward of the barbette
of No. 1 turret.  it is 11.3 inches thick in Iowa and New Jersey,
and 14.5 inches thick in Wisconsin and Missouri.
Even with this bulkhead, there was considerable concern over
the bow armor in the Iowas (of course, there was considerable
concern because of the Navy's discovery that it was impossible
to protect the Iowas from 16/50 AP shell on 45,000ton displacement
anyway -- and so the Iowas are protected from 16/45 at best.)

(actually, if memory serves, fuel oil in capital ships was usually
stored around the sides of the ship to serve as buffers from torpedo
attack, so what happened to Bismark could have happened to many other
ships.)

richard
-- 
-- 
richard welty               welty@algol.crd.ge.com
518-387-6346, GE R&D, K1-5C39, Niskayuna, New York
    ``Every time I see an Alfa Romeo pass by,
         I raise my hat'' -- Henry Ford