A better Imperial Japanese Navy

[mack8]

In the words of Phyllis Nelson.

Hey, baby​

You go your way​

And I'll go mine​

But, in the meantime​

If you want to build bigger and more heavily Furutaka and Aboa classes then arm them with nine 8in guns in three triple turrets so they can fire six guns forward instead of four. It's highly likely that Japan wouldn't lie about their displacement at this point as they had little to gain (because as you wrote they were built before there was a cruiser tonnage quota) and the only reason that I can think of for doing so is to make the declared displacements of the later 8in cruisers appear to be plausible. However, as this ALT-Furutaka/Aboa class has only one gun less than the later Myoko & Takao classes I suggest that you build it as a 10,000ton heavy cruiser in the first place and build another 8 instead of the Myoko & Takao classes. Therefore, you still have twelve Type A cruisers in your timeline but they're all ships with a declared standard displacement of 10,000 tons for a total of 120,000 tons.

That leaves 67,805 tons of replacement tonnage, which could be increased to 68,405 tons because the declared displacement of the OTL Takao class was 9,850 tons. That's enough to build eight OTL Mogami/Tone class. I did it my way so the 8 ships could be built with stronger hulls.

The Japanese operated their cruisers in squadrons of four. So either use your 76,500 tons to build 8 OTL Mogami/Tones and one of my Atlanta analogues or 8 Mogami/Tones with a declared standard displacement of 9,563 tons.

Due to being built before the Washington Naval Treaty (let alone the First Naval London Treaty) the IJN wouldn't have lied about the larger displacement of your Tenryus and Yubari which would reduce the tonnage available for new construction when in the Treaty era.

I can't help but add my own "flavour" to scenarios hence sometimes going on a slightly different way compared to your TL. But our objective so to say is the same (a better IJN). Indeed ideally they would have wanted the Furutakas as full 10,000 tons Myoko sized beasts, but it took time to design the Myokos hence the Furutaka rush job (which aiui were planned before the WNT to beat the Hawkins class). For "flavour" i suggest a compromise in that the first 2 Furutakas are delayed a few months so that their design is quickly stretched and altered to take 8x 20 cm guns in twin mounts. Looking at the laying down timeline it seems that Furutaka, Kako and Aoba can be laid down to this 8 gun design, but there is no excuse for Kinugasa not to be built as a Myoko, since it was laid down about the same time as the first Myokos. I know that they tended to operate the CAs in 4 ship divisions, but since they wanted to squeeze every bit of advantage they could, would make sense to get the biggest cruisers they could as early as possible.

Alternatively maybe there was a way to speed up the Myoko design a bit so that both Aoba and Kinugasa are built as Myokos. Or that and delay Aoba a few months until say spring 1924 so that is laid down as a Myoko. Since earlier we postulated faster cruiser building times, the lost few months can be gradually made up while subsequent ships are built.
So in summary, my own "flavour" is having 2 or 3 ALT-Furutakas, 5 or 6 Myokos, 4 Takaos, 4 Mogamis and 4 Tones (or alternatively 6 Mogamis and 2 Tones, or 8 Mogamis), and if possible (this meaning no bigger Tenryus or Yubari) 1 extra Tone or Mogami for a total of 9 post LNT cruisers.

About post WNT displacements, well they did lie about Akagi and Kaga (which were more like 30,000 tons rather than the declared 26,900), so it makes sense (with hindsight at least) to be a bit more economical with declared cruiser displacements as well. Speaking of the carriers, how about the Akagi and Kaga (or Amagi depending on what TL we follow) be build closer to their 1930s modernized configuration, ie with a single large flight deck and larger hangars, rather than imo utterly idiotic THREE superimposed flight decks in turn inspired by the equally uninspired british 2 superimposed decks design on the follies. Afterall, the US Lexingtons were build with a single large flight deck from the start. Again if nothing else this should save modernization/rebuilding time and money, since the alterations need not be so radical.

There are some pictures on the web of an interim configuration of Kaga studied before it was modernized in 1934-35, that could be a good start for my proposal.

https://www.reddit.com/media?url=https%3A%2F%2Fpreview.redd.it%2F0t4v0cfdpn471.jpg%3Fwidth%3D1024%26format%3Dpjpg%26auto%3Dwebp%26s%3D55788ea57a474d11e767356319e6ffe5508304fc

 

[NOMISYRRUC]

Japanese Naval Guns
Part One - Capital Ship Guns​

Before I write the my post on cruiser design I think it's worth having another look at Japanese naval guns. Can we reduce the number of types as well as improving the performance of individual gun & mounting designs? The source of the following was: http://www.navweaps.com/Weapons/WNJAP_Main.php

Capital ship guns are easy because I want to build a series of 45,000ton fast battleships armed with nine 16.1in guns in three triple turrets instead of the Yamato, "Super Yamato" and B-65 classes. Therefore, no 20.1in/45 because no "Super Yamato", no 18.1in/45 because no Yamato and no 12.2in/50 because no B-65 class. Instead all the effort that went into the design and production of them went into a new 16.1in/45 or 16.1in/50 gun.

According to Naval Weapons it appears that no 12.2in/50 guns were built, so all that was saved was the design work on the gun and turret if any was actually done. But it does say that two 20.1in/45 guns & one gun mount were ordered and construction of them was halted at the start of the Pacific War at which point the first gun was having its breech fitted & the second gun was complete up to the 4A tube and the gun mount & the fittings were mostly complete but unassembled. Naval Weapons also says that twenty-seven 18.1in/45 guns were built, but not the number of turrets, but at least 6 must have been built.

It might be possible to fit this gun to Nagato & Mutsu when they were rebuilt ITTL. Naval Weapons says that forty 16.1in/45 were built for the Nagato, Kaga, Amagi & Kii classes. Therefore, another course of action is to mount eighteen of the twenty-four unused guns ALT-Yamato & ALT-Musashi and build new guns for ALT-Shinano and ALT-No. 111.

 

[NOMISYRRUC]

Japanese Naval Guns
Part Two - Cruiser/ Destroyer Main Guns and Battleship/Cruiser Secondary Guns
Source: http://www.navweaps.com/Weapons/WNJAP_Main.php

Link to Post 276 which was about the differences in performance between the guns and mountings of American and Japanese cruisers and destroyers.

From the above post.

United States Cruiser & Destroyer Guns

8.0in/50 Marks 9 to 16​

3-4 RPG/minute Marks 9 to 15.​

10 RPG/minute Mk 16 aboard the Des Moines class.​

41° maximum elevation​

6.0in/47 Mark 16​

8-10 RPG/minute at 40°​

5° RPG/minute at 60° but measures to increase this to 8-10 RPG/min were proposed.​

40° designed maximum elevation, but increased to 60°​

5.0in/38 Mark 12​

12-15 RPG/minute on pedestal and other mounts lacking integral hoists.​

15-22 RPG/minute on base ring mounts with integral hoists.​

85° maximum elevation.​

Japanese Cruiser & Destroyer Guns

8.0in/50 3rd Year Type Nos. 1 and 2.​

3-5 RPG/minute for No. 1 Gun.​

Except less than 2 RPG/minute in the Furutaka class.​

4-5 RPG/minute for No. 2 Gun, depending upon the ammunition supply system.​

4 RPG/minute in the Aoba and Furutaka classes.​

5 RPG/minute in the later classes, which declined to 2-3 RPG/min at 55° and 2 RPG/min at 70°.​

25, 40, 55 or 70° maximum elevation depending upon the type of turret.​

6.1in/60 3rd Year Type in triple mounting on Yamato class battleships and the Mogami & Ōyodo class cruisers.​

5-6 RPG/minute.​

7 RPG/minute was the theoretical rate of fire,​

but the ammunition hoists could only lift 6 RPG/min and the powder hoists could only lift 5 bags per gun/minute.​

55° maximum elevation.​

5.9in/50 41st Year Type in twin mounting on Agano class. [This should have been 6.0in/50]​

10 RPG/minute theoretical.​

5-6 RPG/minute effective.​

55° maximum elevation.​

5.0in/50 3rd Year Type in single and twin mountings.​

5-10 RPG/minute.​

40-75° maximum elevation depending on the mounting.​

Also slow elevation & training speeds and no AAFCS.​

4.7in/45 10th Year Type.​

10-11 RPG/minute maximum.​

6-8 RPG/minute effective.​

75° maximum elevation.​

3.9in/65 Type 98.​

15-19 RPG/minute.​

90° maximum elevation.​

Therefore, in rate-of-fire terms the IJN & USN 8in guns were about the same. However, the IJN light cruiser & destroyer guns were inferior. Plus the Japanese 5in gun was in a mounting with poor elevation & training rates.

********** ********** **********​

The list of American guns in Post 276 was about half the length of the Japanese list. Yes the American list would have been longer if I'd included the older marks of 6in and 5in guns that were still in service on Pearl Harbour Day. However, the list of Japanese guns would have been longer if I'd included the performance of the older medium & light calibre guns that were still in service on Pearl Harbour Day and with hindsight I should have included the 5.5in/50 and 5.0in/40.

As the POD's 1917 I think the IJN should have retained the 6.0in calibre as the main armament of its light cruisers & secondary armament for larger warships. So no 6.1in and 5.5in guns. Also I think it should have retained the 4.7in calibre as the main armament for its destroyers & secondary armament for larger warships. So no 5.0in and 3.9in guns. Reducing the number of calibres and gun mountings may or may not have produced better performing weapons, but it would have reduced the logistical burden and may have allowed more guns & mountings to be built through the use of larger scale production methods.

 

[NOMISYRRUC]

Japanese Naval Guns
Part Three - Smaller Calibre and Anti-Aircraft Guns
Source: http://www.navweaps.com/Weapons/WNJAP_Main.php

That's the list. What Japan needs to do is buy licences to build the Bofors 40mm & Oerlikon 20mm and learn how to mass produce them PDQ or develop substitute weapons of their own. Whether they could have done so is another matter.

As the table indicates some Bofors guns were captured at Singapore and one was used to produce a Japanese copy. According to Naval Weapons the prototype underwent firing trials in 1943 and limited production began later that year. However, it hadn't been put into large scale production before VJ Day.

 

[mack8]

Japanese Naval Guns
Part One - Capital Ship Guns​

Before I write the my post on cruiser design I think it's worth having another look at Japanese naval guns. Can we reduce the number of types as well as improving the performance of individual gun & mounting designs? The source of the following was: http://www.navweaps.com/Weapons/WNJAP_Main.php

View attachment 885179​

Capital ship guns are easy because I want to build a series of 45,000ton fast battleships armed with nine 16.1in guns in three triple turrets instead of the Yamato, "Super Yamato" and B-65 classes. Therefore, no 20.1in/45 because no "Super Yamato", no 18.1in/45 because no Yamato and no 12.2in/50 because no B-65 class. Instead all the effort that went into the design and production of them went into a new 16.1in/45 or 16.1in/50 gun.

According to Naval Weapons it appears that no 12.2in/50 guns were built, so all that was saved was the design work on the gun and turret if any was actually done. But it does say that two 20.1in/45 guns & one gun mount were ordered and construction of them was halted at the start of the Pacific War at which point the first gun was having its breech fitted & the second gun was complete up to the 4A tube and the gun mount & the fittings were mostly complete but unassembled. Naval Weapons also says that twenty-seven 18.1in/45 guns were built, but not the number of turrets, but at least 6 must have been built.

It might be possible to fit this gun to Nagato & Mutsu when they were rebuilt ITTL. Naval Weapons says that forty 16.1in/45 were built for the Nagato, Kaga, Amagi & Kii classes. Therefore, another course of action is to mount eighteen of the twenty-four unused guns ALT-Yamato & ALT-Musashi and build new guns for ALT-Shinano and ALT-No. 111.

Japanese Naval Guns
Part Two - Cruiser/ Destroyer Main Guns and Battleship/Cruiser Secondary Guns
Source: http://www.navweaps.com/Weapons/WNJAP_Main.php

View attachment 885176​

From the above post.

United States Cruiser & Destroyer Guns

8.0in/50 Marks 9 to 16​

3-4 RPG/minute Marks 9 to 15.​

10 RPG/minute Mk 16 aboard the Des Moines class.​

41° maximum elevation​

6.0in/47 Mark 16​

8-10 RPG/minute at 40°​

5° RPG/minute at 60° but measures to increase this to 8-10 RPG/min were proposed.​

40° designed maximum elevation, but increased to 60°​

5.0in/38 Mark 12​

12-15 RPG/minute on pedestal and other mounts lacking integral hoists.​

15-22 RPG/minute on base ring mounts with integral hoists.​

85° maximum elevation.​

Japanese Cruiser & Destroyer Guns

8.0in/50 3rd Year Type Nos. 1 and 2.​

3-5 RPG/minute for No. 1 Gun.​

Except less than 2 RPG/minute in the Furutaka class.​

4-5 RPG/minute for No. 2 Gun, depending upon the ammunition supply system.​

4 RPG/minute in the Aoba and Furutaka classes.​

5 RPG/minute in the later classes, which declined to 2-3 RPG/min at 55° and 2 RPG/min at 70°.​

25, 40, 55 or 70° maximum elevation depending upon the type of turret.​

6.1in/60 3rd Year Type in triple mounting on Yamato class battleships and the Mogami & Ōyodo class cruisers.​

5-6 RPG/minute.​

7 RPG/minute was the theoretical rate of fire,​

but the ammunition hoists could only lift 6 RPG/min and the powder hoists could only lift 5 bags per gun/minute.​

55° maximum elevation.​

5.9in/50 41st Year Type in twin mounting on Agano class. [This should have been 6.0in/50]​

10 RPG/minute theoretical.​

5-6 RPG/minute effective.​

55° maximum elevation.​

5.0in/50 3rd Year Type in single and twin mountings.​

5-10 RPG/minute.​

40-75° maximum elevation depending on the mounting.​

Also slow elevation & training speeds and no AAFCS.​

4.7in/45 10th Year Type.​

10-11 RPG/minute maximum.​

6-8 RPG/minute effective.​

75° maximum elevation.​

3.9in/65 Type 98.​

15-19 RPG/minute.​

90° maximum elevation.​

Therefore, in rate-of-fire terms the IJN & USN 8in guns were about the same. However, the IJN light cruiser & destroyer guns were inferior. Plus the Japanese 5in gun was in a mounting with poor elevation & training rates.

********** ********** **********​

The list of American guns in Post 276 was about half the length of the Japanese list. Yes the American list would have been longer if I'd included the older marks of 6in and 5in guns that were still in service on Pearl Harbour Day. However, the list of Japanese guns would have been longer if I'd included the performance of the older medium & light calibre guns that were still in service on Pearl Harbour Day and with hindsight I should have included the 5.5in/50 and 5.0in/40.

As the POD's 1917 I think the IJN should have retained the 6.0in calibre as the main armament of its light cruisers & secondary armament for larger warships. So no 6.1in and 5.5in guns. Also I think it should have retained the 4.7in calibre as the main armament for its destroyers & secondary armament for larger warships. So no 5.0in and 3.9in guns. Reducing the number of calibres and gun mountings may or may not have produced better performing weapons, but it would have reduced the logistical burden and may have allowed more guns & mountings to be built through the use of larger scale production methods.

Japanese Naval Guns
Part Three - Smaller Calibre and Anti-Aircraft Guns
Source: http://www.navweaps.com/Weapons/WNJAP_Main.php

View attachment 885182​

That's the list. What Japan needs to do is buy licences to build the Bofors 40mm & Oerlikon 20mm and learn how to mass produce them PDQ or develop substitute weapons of their own. Whether they could have done so is another matter.

As the table indicates some Bofors guns were captured at Singapore and one was used to produce a Japanese copy. According to Naval Weapons the prototype underwent firing trials in 1943 and limited production began later that year. However, it hadn't been put into large scale production before VJ Day.

Not much i can add as it in large part coresponds to my own views on the subjects. Iirc there was design work (not sure if prototypes as well) on a 41cm/50 gun and triple turrets for the planned post-1930 battleships (but postponed by the LNT). And i believe at the same time there was also work on a 20cm/55 gun for the Takao-kai, so focusing on these two means the ALT-Yamato has the 41cm/50, as well as the 8 ITTL Mogami/Tones (if they are still rearmed) can be armed with these 20cm/55 guns.

However, arming the first 2 ATL-Yamatos with the existing 41cm/45 is the best choice economy wise, as instead of those more AA guns can be built. And probably the same should apply to cruiser guns, rather than replace the older 20cm guns with the newer models at big expense and resource expenditure perhaps it's better for the cruisers to retain their original guns (so Mogamis/Tones are not rearmed), while again those resources are directed towards more AA guns, so that preferably by WW2 all major combatants have DP 12cm/45 or 12cm/50 guns with improved mountings and rates of fire more or less equal to those of the US 5in/38.

As far as autocannons go, Bofors is the best choice but if not available, perhaps a development of the 40mm pom-pom IJN already have would be good enough, this coupled with 20mm Oerlikon autocannons.

 

[NOMISYRRUC]

Just a quick comment, ITTL i have the ALT-Ryujo built at Kawasaki because AIUI it went temporarily bankrupt in 1931 for lack of orders, and it seems between launching Maya in 1930 and starting the Kumano in 1934 they haven't built anything major that i could find info on, so they would have plenty of space for a fleet CV, possibly even two one after the other.

In the course of the research I'm doing for my next "proper" post I discovered that Maya was laid down 8 months late due to the bankruptcy of Kawasaki in 1927. My source for that is Page 121 of "Japanese Cruisers of the Pacific War" by Lacroix and Wells.

 

[mack8]

I will check it out, though my understanding is that they went bankrupt in 1931, July 20th to be precise.
See page 4 of the file below.
Looking forward to your next post.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwidqt250oyEAxV70QIHHQb8CSsQFnoECBgQAQ&url=https%3A%2F%2Fglobal.kawasaki.com%2Fen%2Fcorp%2Fhistory2%2F125history_02_e.pdf&usg=AOvVaw13YnIV-kUv9Ra3zn7uZH9E&opi=89978449

 

[mack8]

In the course of the research I'm doing for my next "proper" post I discovered that Maya was laid down 8 months late due to the bankruptcy of Kawasaki in 1927. My source for that is Page 121 of "Japanese Cruisers of the Pacific War" by Lacroix and Wells.

I read the page, very interesting. Further to that on japanese wiki i found the following (translated):

The company also faced a financial crisis during the economic downturn that followed World War I. At this time, the labor dispute of 1919 (Taisho 8) , the Washington Disarmament Treaty of 1922 (Taisho 11) , and the Great Kanto Earthquake of 1923 (Taisho 12) all coincided. Furthermore, due to the financial crisis of 1927 (Showa 2), the main bank , Jugo Bank, was temporarily closed, and the company's cash flow rapidly deteriorated. The company sought to rebuild its business with aid from the government and the city of Kobe , layoffs for approximately 3,500 employees , cuts in executive compensation, and personal funds provided by the Matsukata and Kawasaki families. In addition, the Hyogo factory was separated and became independent as ``Kawasaki Sharyo'', and a mortgage was established and the company received a loan using the main factory and the Fukiai factory as collateral. The Japanese Navy also established a temporary ship construction department in the Naval Administration Headquarters to help continue ship construction.


However, orders for new ships further decreased due to the Great Depression that started on Wall Street in the United States , and in 1931 (Showa 6), the company applied for a peace agreement , was approved the following year, and completed the peace agreement process in 1933 (Showa 8) . . In order to rebuild the company, 3,260 people were laid off and internal costs were reduced. Outside the company, new commercial shipbuilding was revived thanks to the government's new shipbuilding aid, and the economy improved after the Manchurian Incident , and the company's rebuilding was on track.

Also, something that i did not realized till now, since both Kinugasa and Ashigara were being built at the same time at Kawasaki, it seems they had a second slip big enough to take a Kinugasa size ship (185 metres) at least, which should be at least 200 metres long? So the few figures circulating online re the Kawasaki Kobe slipway sizes needs to be altered, should be one of at least 275 metres long (to take Zuikaku/Taiho), and one 200 metres long (Kinugasa).

 

[NOMISYRRUC]

Does giving more technical assistance to the Kreigsmarine and Regia Navale from the middle 1930s onwards count as a better IJN?

Making the navies of their allies more effective so they sank and tied down more RN & USN ships, means fewer RN & USN ships to fight the IJN, which is in accord with its strategy to wear down those navies until the IJN has near parity and can fight the decisive battle.

 

[Sekhmet_D]

Does giving more technical assistance to the Kreigsmarine and Regia Navale from the middle 1930s onwards count as a better IJN?

Making the navies of their allies more effective so they sank and tied down more RN & USN ships, means fewer RN & USN ships to fight the IJN, which is in accord with its strategy to wear down those navies until the IJN has near parity and can fight the decisive battle.

This is a very intriguing prospect. IOTL, however, Japan clearly did not trust Germany enough to share some of their most important technological breakthroughs, including the Long Lance torpedo and Yamato class battleship (perhaps they anticipated becoming enemies after the Allies were beaten).

 

[scifilovr]

Does giving more technical assistance to the Kreigsmarine and Regia Navale from the middle 1930s onwards count as a better IJN?

Making the navies of their allies more effective so they sank and tied down more RN & USN ships, means fewer RN & USN ships to fight the IJN, which is in accord with its strategy to wear down those navies until the IJN has near parity and can fight the decisive battle.

The RN maybe, but the Italians and the Germans would have to sink a lot of USN ships to get the USN anywhere close to parity. A statistic from Kaigun by Evans and Peattie that absolutely boggles my mind is that if the Japanese had sunk the entire US Navy, not just every ship at Pearl Harbor, but the entire prewar US Navy on December 7th, 1941 and then completed every single shipbuilding program they had planned from 1941-1945, the United States would still have built a bigger Navy.

 

[NOMISYRRUC]

This is a very intriguing prospect.

I was thinking of helping Germany and Italy develop naval aviation (shore & sea based) and aircraft carriers. I know that some Kriegsmarine & Luftwaffe officers went to Japan to study naval aviation and the IJN let German naval architects study some of the older aircraft carriers design.

Therefore, I was thinking of the following.

• More Kriegsmarine, Luftwaffe, Regia Aeronautica & Regia Marina officers go to Japan to study naval aviation.
• The IJN encourages their allies to develop shore based anti-shipping forces, by providing training and helping them to develop good air-launched torpedoes sooner and armour piercing bombs.
• Help the Kriegsmarine develop a better Graff Zeppelin class. The OTL class had the potential to be formidable because they were of similar size to the Essex and Shōkaku classes. Similarly, they also provide technical assistance to the Regia Marina when they convert their liners to aircraft carriers.
• Help the Luftwaffe with the design of carrier aircraft. Maybe they sell some to Germany which were delivered via the USSR before Operation Barbarossa and/or let them build Japanese designs under licence.

IOTL, however, Japan clearly did not trust Germany enough to share some of their most important technological breakthroughs, including the Long Lance torpedo and Yamato class battleship (perhaps they anticipated becoming enemies after the Allies were beaten).

I'd not though of that as a reason why they didn't share those innovations with their allies, but it sounds rather plausible now you mention it.

I thought not telling them about oxygen driven torpedoes may have been because they wanted to keep it secret from the Americans & British as they wanted it to be a nasty surprise for the RN & USN when they fought them directly. What is why that technology is one thing the IJN wouldn't share with their allies ITTL or at least not until they were in the war.