Could This Be KASUMI?

Discussions on all aspects of the Japanese Empire, from the capture of Taiwan until the end of the Second World War.
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fontessa
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Location: Yokohama, Japan

Re: Could This Be KASUMI?

Post by fontessa » 14 Dec 2021 08:18

I posted about San Juan Atlanta-class light cruiser and modified IJN Isuzu and felt sad. So I checked about IJN Akizuki-class destroyer most powerful air defense ship in IJN and felt sad again.

Akizuki was developed for the direct guard of aircraft carriers. She was 50% larger than a normal destroyer and was called 直衛艦 Direct Guard Ship. (Administratively classified as a destroyer) At first she was planned to equip only anti-aircraft guns, but the poor IJN added a quadruple torpedo launcher with four spare torpedoes, saying, "If we make her anyway, it's a waste without torpedoes." IJN, which had extremely powerful torpedoes called 酸素魚雷 Oxygen Torpedo, placed great importance on torpedo warfare. Almost all IJN cruisers and destroyers were equipped with even spare torpedoes.

See the 1st picture, Akizuki’s anti-aircraft artillery procedure was as the below;
(1) Send directional data and range data from the tower to the range keeper in the controlling room.
(2) Based on the data of (1) and the data from main compass, the turning angle of the turret, the elevation angle of the gun, and the fuze adjustment value calculated by the range keeper are sent to the turret.
(3) (2) is transmitted to the turret as the movement of the 基針 target needle. In the turret, the operator set the 追針 chasing needle to the target needle.
(4) Once the chasing needle is in contact with the target needle, the former is locked to later. That is, rotation and elevation of the turret is controlled by the operation of the tower operators. In the case of a battleship, when the tower gunner pulls the trigger, only guns with the chasing needle locked to the target needle are fired. In the case of Akizuki, the rate of fire is high, so the gunner inside the turret fires.

It have been believed that Akizuki had 2 sets of Type 94 Fire Control System (red and blue) and rear blue set was replaced with a 25mm Triple Machine Cannon in the 3rd refurbishment as shown in the 2nd picture. When I saw it at the first time, I felt it was an irrational measure that weakens her ability, so I checked about it. In fact, she had only one set of red Type 94 Fire Control System. The 3nd picture is a picture of 4th ship Fuyuzuki of Akuduki-class destroyers in her official test. The white waves created by her bow had reached the funnel, indicating that her speed was full 33 knots. If we look closely at the red and blue towers, we can see that the blue tower did not have a rangefinder, it was an empty tower. The 4th picture is the photo taken by a B-17. It's hard to see, but all four turrets were pointed diagonally behind the port side. It means all four turrets were controlled by the forward Type 94 Fire Control System. For the IJN, which did not have an effective fire control radar, this would have been a realistic solution. Finally, I found that the Japanese recent magazine "太平洋戦史シリーズ Vol.23 History Group Image Pacific War History Series Vol.23" has collected many recollections of the crew of the Akizuki-class destroyers, "There was only one FCS from the beginning."

The 5th picture is again USS San Juan, CL-54 of Atlanta-class light cruiser. She had 2 sets of Mk.37 Fire Control System. As Mk.37 FCS had both range and height radars, its accuracy was higher than that of IJN Type 94 FCS. In addition, the US Navy had the "Magic Fuze" which also improved the accuracy. Akizuki-class destroyers weren't a match for Atlanta-class light cruisers.

秋月 00.jpg

秋月 改装.jpg

秋月級 初月.jpg

秋月 1.jpg

秋月 San Juan.jpg

fontessa
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KevDen
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Location: East of Woodstock, west of Vietnam

Re: Could This Be KASUMI?

Post by KevDen » 14 Dec 2021 12:10

Hi Fontessa,

Below is a photo grab from an old video (non HD) of what remained of the coral encrusted triple 25mm in the aft position you mention on the Akizuki Class DD's (this photo from the wreck of Shimotsuki in 2003).

For anyone interested some info about the wreck can be found towards the bottom of the page here; http://www.combinedfleet.com/atully08.htm
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“We are off to look for trouble. I expect we shall find it.” Capt. Tennant, HMS Repulse. 8 December 1941
“A review of the situation at about 11.00 was not encouraging.” Capt. Gordon, HMS Exeter. 1 March 1942

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fontessa
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Location: Yokohama, Japan

Re: Could This Be KASUMI?

Post by fontessa » 16 Dec 2021 15:47

KevDen wrote:
14 Dec 2021 12:10
Hi Fontessa,

Below is a photo grab from an old video (non HD) of what remained of the coral encrusted triple 25mm in the aft position you mention on the Akizuki Class DD's (this photo from the wreck of Shimotsuki in 2003).

For anyone interested some info about the wreck can be found towards the bottom of the page here; http://www.combinedfleet.com/atully08.htm
Thanks.

First 6 destroyers up tol Wakatsuki were built with empty tower (later replaced with 25mm gun), and rest 7 destroyers from Shimozuki were built with 25mm gun. Reffer to the 1st and 2nd pictures.
The 3rd picture shows Akizuki in official test. Note that the front tower looks also empty. The Type 94 FCS that wasn't in time may have been added later.

DD 秋月 1.jpg

DD 秋月 2.jpg

秋月.jpg

fontessa
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