Would Yamato with advanced AA gunnery survive air attack ?

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alecsandros
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Would Yamato with advanced AA gunnery survive air attack ?

Post by alecsandros » Wed Dec 28, 2011 8:58 am

Hello guys,

After the discussion with Michael, a question came to me: Would Yamato and Musashi escape being sunk if they would have had AA artillery comparable to that of US battleships ? That would include:
- 40 x Bofors 40mm (quads, totalling 160 guns)
- 20 x 127mm rapid-firing guns.

- advanced radar-guided fire control
- proximity fuzes for the shells
- ... etc

What do you think ?

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by Ken Thompson » Wed Dec 28, 2011 4:59 pm

What they needed is CAP or combat air patrol to intercept and breakup the incoming attack just like the POW and Repulse needed. Late in the war the American tactic was for fighter planes with machine guns and rockets to take out the AA first. AA is most effective in point defense as in the Okinawa radar patrol ships shot down a lot of planes because they were coming right at them and there was no deflection required.

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Rick Rather
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Re: Would Yamato with advanced AA gunnery survive air attack

Post by Rick Rather » Sun Jan 01, 2012 12:57 pm

Interesting question. It stands to reason that if the Big Boys have the Good Toys, then their escorts would too. The obvious question then comes to mind, could a similarly composed US group, without air cover, avoid being mauled when set upon by 259 Jills, Judys & advanced Zekes. I'd like to game it out, but my instinct is probably not. This takes us back to, can US AA combined with Yamato-armor provide sufficient protection.

Another variable is quality of damage control. The USN has always taken a very aggressive "lessons-learned" approach to DC. How much protection does good damage control & isolation provide?
Just because it's stupid, futile and doomed to failure, that doesn't mean some officer won't try it.
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19kilo
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Re: Would Yamato with advanced AA gunnery survive air attack

Post by 19kilo » Sun Jan 01, 2012 4:32 pm

Would Yamato with US style AA armament survive air attack with German Fritz-X?

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by RNfanDan » Sun Jan 01, 2012 9:27 pm

What am I missing here? Yamato and Musashi were both piled like MOUNTAINS with AA. Surely their volume of fire equalled, at the very least, that of any contemporary US battleship?

Granted, their small caliber weapons weren't effective against attacking aircraft, but this was the same situation for the USN at the time with its masses of 20mm---they were only useful at shorter ranges, and could shoot down aircraft pretty well only AFTER the planes had already discharged their payloads. Too late to prevent anything except possibly the planes making a second trip back.

I'm afraid that without advance air cover / CAPs, even the Holier-than-thou Iowas would have been sunk. Radar-directed barrage fire and masses of light weapons could only go so far, and eventually the guns would simply have too many targets zipping around to down them all, let alone the mass quantities of ammunition needed to do it. Yamato and Musashi were like large animals under attack by swarming Africanised bees.

Can't wait to see the arguments against me, surely to be profferred!

:lol:
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Re: Would Yamato with advanced AA gunnery survive air attack

Post by Pandora » Sun Jan 01, 2012 10:21 pm

hello,
interesting post. what about a couple of modern Phalanx CIWS? woud that make the difference shotting down vintage wwii planes? :D

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by alecsandros » Mon Jan 02, 2012 9:44 am

RNfanDan wrote:What am I missing here? Yamato and Musashi were both piled like MOUNTAINS with AA. Surely their volume of fire equalled, at the very least, that of any contemporary US battleship?
No, the volume of fire was far lower.

Yamato 1945, 24 x 127mm + 162 x 25mm (my numbers vary here, but I'll take the maximum for this)
Iowa 1945, 20x 127mm, 49 x 20mm, 80 x 40mm.

Rates of real fire :
Yamato
127mm ~ 8-10 rpm
25mm/L60 ~ 110-120rpm (because of the very small 15-shell cartridges that had to be resupplied manualy)

TOTAL: 10 x 24 + 120 x 162 = 19680 shells/minute

Iowa
127mm ~ 12-18 rpm
Oerlikon 20mm ~ 250-320 rpm
Bofors 40mm ~ 120 rpm

TOTAL: 18 x 20 + 49 x 320 + 80 x 120 = 25640 shells/minute

====

So, a late-war Iowa class could output about 25% more shells into the air than a Yamato class. But that doesn't tell the entire story: the effective range of the Bofors 40mm (the main AA assett on board Iowa) was between 7-10km, depending on elevation. The eff range of Japanese 25mm was around 3km.

And it gets worse:
According to US Naval Technical Mission to Japan report O-47(N)-2, the Japanese saw the following deficiencies in these 25mm mountings in decreasing order of seriousness:
a) The multiple mounts could not be trained and elevated rapidly enough, either by power or manual drive.
b) The gunsights were inadequate against high speed aircraft.
c) The guns had excessive vibration, making them difficult to keep on target.
d) The capacity of the ammunition supply equipment was inadequate, causing interrupted fire and a greatly reduced operating routine.
e) The muzzle blast caused problems for both the guncrew and equipment.

5) Apparently, all magazines had to be loaded by hand as no specialized loading equipment was ever developed.

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by alecsandros » Mon Jan 02, 2012 10:49 am

19kilo wrote:Would Yamato with US style AA armament survive air attack with German Fritz-X?
:D :D :D

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by Byron Angel » Mon Jan 02, 2012 3:09 pm

alecsandros wrote:the effective range of the Bofors 40mm (the main AA assett on board Iowa) was between 7-10km, depending on elevation. The eff range of Japanese 25mm was around 3km.

Dear Alec,

There are some very good documents to be found in hyperwar/ibiblio re USN AAA doctrine and experience. From what I've read, the open fire ranges of of USN AA was, broadly speaking, about as follows -
5in/38 @ 8,000 yards
40mm @ 4,000 yards
20mm @ 2,000 yards
- governed by the estimated accuracy of the fire control efficiency of the respective weapons.

Interestingly enough, even with VT fusing for the 5in/38 in 1944, the big AAA killers were apparently still the 40mm and 20mm.


BTW, interesting comments on the Japanese assessments of their 25mm AA weapon.


Happy New Year to you / Byron

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by Thorsten Wahl » Mon Jan 02, 2012 3:40 pm

Iowa
127mm ~ 12-18 rpm
Oerlikon 20mm ~ 250-320 rpm
Bofors 40mm ~ 120 rpm

TOTAL: 18 x 20 + 49 x 320 + 80 x 120 = 25640 shells/minute
Did you have an idea about how many shells these ships carried.


BTW german outfit for 20mm
Bismarck 1941 carries ~44.000 shells for 20mm
Tirpitz 1944 carries ~138.000 shells for 20mm.
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Re: Would Yamato with advanced AA gunnery survive air attack

Post by dunmunro » Mon Jan 02, 2012 11:07 pm

Pandora wrote:hello,
interesting post. what about a couple of modern Phalanx CIWS? woud that make the difference shotting down vintage wwii planes? :D
Phalanx is just an updated pom-pom/MkIV pom-pom director. The 8 barreled pom-pom, when operated by RPC required NO crew, (just one man was needed to override the RPC if it ran wild) and in turn was controlled by a Mk4 pom-pom director which used radar ranging and gyro gunsights, but it in turn, could be controlled by one man in emergency situations. Theoretically, any plane targeted by a pom-pom/MkIV pom-pom director was doomed, but the problem, as always was target acquisition. In one famous incident an FAA pilot released his drop tank near KGV and this was immediately engaged by her AA. Phalanx would have the same problem in trying not to acquire the wrong targets. For example an F6F fires a salvo of rockets at Yamato, while at the same time TBs are making an attack run; does the phalanx engage the F6F, the TBF or the rockets, because all will appear as valid targets.

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by alecsandros » Tue Jan 03, 2012 6:39 am

dunmunro wrote:
Pandora wrote:hello,
In one famous incident an FAA pilot released his drop tank near KGV and this was immediately engaged by her AA..
Hello Duncan,
What kind of AA control did KGV had ? Could it be used also against free-falling bombs ?

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by dunmunro » Tue Jan 03, 2012 6:52 am

alecsandros wrote:
dunmunro wrote:
Pandora wrote:hello,
In one famous incident an FAA pilot released his drop tank near KGV and this was immediately engaged by her AA..
Hello Duncan,
What kind of AA control did KGV had ? Could it be used also against free-falling bombs ?
Am empty drop tank falls much more slowly than a free falling bomb. The point is that acquiring the correct target is always a problem.

However, KGV used 7 or 8 Mk4 pom-pom directors, probably all with RPC by 1944/45 to control her Octuple pom-poms.

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Re: Would Yamato with advanced AA gunnery survive air attack

Post by alecsandros » Tue Jan 03, 2012 7:52 am

dunmunro wrote:
However, KGV used 7 or 8 Mk4 pom-pom directors, probably all with RPC by 1944/45 to control her Octuple pom-poms.
What I find very interesting is that the AA guns fired automatically, without human intervention... Pretty neat, isn't it ?

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Rick Rather
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Re: Would Yamato with advanced AA gunnery survive air attack

Post by Rick Rather » Tue Jan 03, 2012 8:28 am

The other catch with Phalanx is that it has limited ammunition. It has enough for 5-6 engagements, then it must be reloaded. This takes some time - 10-15 minutes, IIRC. In a Sibuyan Sea-type scenario, this is mitigated by the fact that the 259 attacking aircraft came in many waves over several hours - not all at once. There was time between each wave for reloading.
Just because it's stupid, futile and doomed to failure, that doesn't mean some officer won't try it.
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