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Desu_Yuki
Post subject: Zao Class Heavy Cruiser: IJN KunimiPosted: September 19th, 2017, 3:21 am
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Welp, had this modified design sitting in dry dock for awhile now, guess it's time for her sea trials!

The Zao class heavy cruisers were a class of 3 ships. The lead of which was named Zao, followed by Senjo and Kunimi. The class became one of the most advanced heavy cruisers of the time.

The class was designed taking in account lessons learned from older Japanese cruiser designs. And with Japan no longer having to bide by any naval treaty the ship designers were able to create a ship without major restrictions.

Both Zao and Senjo were completed relatively the same. Zao and Senjo measured 225 meters with a beam of 20.2 meters and a draft of 6.5 meters. Kunimi was completed with a length of 210 meters. The class was installed with 8 Kampon boilers, producing a total of 160,000 shp driving 4 steam turbines give the Zao class a top speed of about 35 knots. The class weighed about 13,000 tons and 16,000 fully loaded, Kunimi weighed slightly less but this difference is negligible.

Belt armor was around 165mm, Gun turrets were 30mm, the barbettes were 25-100mm and the conning tower was 100mm (removed in 1941 refit.) All ships of the Zao class carried quadruple torpedo launchers, two on each side, four in total. One strange difference is that class only carried a single catapult while most ships in which the Zao class was based off of carried at least two. The deck was armored to resist hits from 500 pound bombs.

Both Zao and Senjo were completed with new triple 203mm gun turrets, however the turrets proved too troublesome and both ships were rearmed with the standard 203 double turrets. N 1939, Kunimi was used as a test bed for the new: Type 1 252mm year 1 guns.

The guns featured a new semi automatic loading system. The new system removed the need for sailors to man the main turret and loading powder bags. The Sailors were only need for the loading of the shells to the turret. The loading and sending of bag chagres were done the ship's computer. While in theory the system worked well in practice the system was clumsy and prone to breakdown if not handled properly. It took until 1941-2 for the teething problems of the turrets to be resolved.

While reload time was reduced by 50% the time it took to train the men to operate the turrets and that special handling it required, meant that only Kunimi was fitted with this armament system. The reason Kunimi kept the guns was due to the huge amount of rewiring that would have been required.

The class were fitted with 8 double 140mm secondary gun turrets, in reality hey we're only place holders until the 100mm DP guns were ready.

However there was a flaw in the design, that was in the placement of the torpedo tubes. The tubes were all placed just above the propeller shafts and rudder. This was a flaw that wasn’t realized until the sinking of both Zao and Senjo in which detonation of the torpedo's severed the stern of both the ships. Kunimi’s tubes were moved forward away from the propellers in an attempt to reduce the danger, however it was still close. Another flaw was that a small hatch and thin bulkhead separated the torpedo bay from a small passage way that lead down into the rear magazines. This was a major factor in the sinking of Zao. However it is debated in whether or not it made a difference
in reducing the threat of magazine detonation if the torpedo's exploded.

[ img ]
Kunimi as she appeared in 1939
[ img ]
Kunimi as she appeared in 1944, torpedo tubes have been moved away from the stern. The 1944 a design flaw in which the torpedo bay was connected to the rear magazines. The additional 100mm DP AA gun is prominent, as is the different superstructure when compared to Zao.
[ img ]
Zao is the oldest sister, she is longer then Kunimi and has a different bow design. Along with the old torpedo tube placement and 2 less 100mm DP AA gun turrets.

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Anyways, credit to the legendary BB1987 who's work I based my own off of.
So what do you guys think? Did I do well with one of my very first designs? Looking foreward to what you guys think.


Last edited by Desu_Yuki on September 25th, 2017, 3:47 am, edited 1 time in total.

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Tobius
Post subject: Re: Zao Class Heavy Cruiser: IJN KunimiPosted: September 19th, 2017, 5:45 am
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There are a lot of "American" features in the design.


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Shigure
Post subject: Re: Zao Class Heavy Cruiser: IJN KunimiPosted: September 19th, 2017, 1:28 pm
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The Zao this ship was kitbashed from is a real neverbuilt design

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Colosseum
Post subject: Re: Zao Class Heavy Cruiser: IJN KunimiPosted: September 19th, 2017, 2:14 pm
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Cool, though it looks like your image host has resized the images and they are a bit blurry. Try using imgur and reposting them.

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acelanceloet
Post subject: Re: Zao Class Heavy Cruiser: IJN KunimiPosted: September 19th, 2017, 5:36 pm
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Quote:
The guns featured a new semi automatic loading system. The new system removed the need for sailors to man the main turret and loading powder bags. The Sailors were only need for the loading of the shells to the turret. The loading and sending of bag chagres were done the ship's computer. While in theory the system worked well in practice the system was clumsy and prone to breakdown if not handled properly. It took until 1941-2 for the teething problems of the turrets to be resolved.
you mean an autoloader, unmanned turret and an selector for which projectile to load next? I don't see the need for an computer there, and even worse, I can't think of any computer (called that at the time) existing at the time to do this. Keep in mind, one of the first computers fitted on board ships would be the Mk 1 fire control computer, part of the Mk 37 gun fire control system. These were, unlike the computers we know today, completely mechanical systems. in your system, I do not see the need for any computations, I do see the need to do a lot of mechanical movements though. this would been done at the time by careful gearing and designing an mechanical system.

Autoloaders for guns this size started to appear at the end of the war, in the royal navy and US navy IIRC. They were only perfected after the war though (and even then were considered unreliable, although that might have had something to do with the high rate of fire then required).

In addition, I have never heard of any gun system of a gun this size having an unmanned turret. we see unmanned turrets appearing around the 1960's, IIRC, but even then only on small weapons. The Mk 71, developed in the 1970's and cancelled in 1978, was an autoloader 8in gun with an low rate of fire and in a single mounting. It still used a crew of 6 men.

In short, what exactly is this loading system supposed to be, and why did you have it available in 1939? and why did it require something called an computer?
Tobius wrote: *
There are a lot of "American" features in the design.
What kind of American features? I have absolutely no idea what you are talking about Tobius? What are you saying with your comment, is it something that needs changing? something that is wrong? something that is interesting? right now it is just like you just want to add information which says exactly nothing :P

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Tobius
Post subject: Re: Zao Class Heavy Cruiser: IJN KunimiPosted: September 20th, 2017, 1:15 pm
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Sensor suite, aircraft handling arrangements that are "non-Japanese".

The Japanese in between the wars were developing optics augments and horizon spotting systems that relied on the human eye. They did not use radio countermeasure and sensing systems until 1944. They did not have the ability until they absorbed British tech captured from Singapore and reverse engineered in 1942-1943 The stern deck fantail catapult is a feature seen on some French and many American ships (Jean Bart and Richilieu battleships for France after US refits, many post 1936 American heavy and large cruiser classes and fast `battleships): rarely seen on Japanese ships (Yamatos for example). Same for that type crane mounted there.


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Desu_Yuki
Post subject: Re: Zao Class Heavy Cruiser: IJN KunimiPosted: September 25th, 2017, 4:03 am
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Autoloaders for guns this size started to appear at the end of the war, in the royal navy and US navy IIRC. They were only perfected after the war though (and even then were considered unreliable, although that might have had something to do with the high rate of fire then required).

In addition, I have never heard of any gun system of a gun this size having an unmanned turret. we see unmanned turrets appearing around the 1960's, IIRC, but even then only on small weapons. The Mk 71, developed in the 1970's and cancelled in 1978, was an autoloader 8in gun with an low rate of fire and in a single mounting. It still used a crew of 6 men.

In short, what exactly is this loading system supposed to be, and why did you have it available in 1939? and why did it require something called an computer?
Thanks for your feedback.

You are correct in that Kunimi's loading system might be a to advanced for the time. To be honest, I haven't found the time to completely work out how it operates in my head quite yet, School and all. Not to mention the description was written in the last 2 weeks of summer.

In retrospect, giving her such advanced technology was because I wanted to give Kunimi a reason to stick around, considering her armament of 8 guns compared to 12 on her older sisters. I felt that it would be redundant to keep a ship that packs less of a punch, is smaller and requires the same amount of food, supply's, etc. Her strange gun caliber follows the same idea. Plus the fact that I kinda built her in a carefree matter didn't help when it came in the historical accuracy department.

Soo...if you have any ideas that would be a bit more historically accurate then it would be greatly appreciated.
I thank you in advance for taking the time to review Kunimi.

edit: forgot to end quote kappa~


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