Rn vs IJN

[z42]

The Japanese could not actually build what they wanted, they could not afford it.
They had gone to the 5.5 in guns because the lighter weight shells were easier to manhandle to the guns from the hoists.

Land-based artillery in the modern era has pretty much standardized on the 6" size, as that's about the largest shell that can be manhandled if necessary, and also that's about the maximum size of a gun that can be installed on a SP platform, provide some splinter protection for the crew, and still be road mobile.

For sea-based artillery conditions are more cramped, and the platform is moving and pitching, moving the maximum size that can be manhandled downwards. Consensus seems to be that somewhere around 5" is the maximum that can be manhandled in a somewhat sustained fashion without tiring the gun crews too fast.

Now please note that this was a limit to the British 5.25in AA guns which failed to reach the desired rate of fire.

Yes, the Brits waffled around with a number of different guns in this class until they developed and then standardized on the 4.5", which by all accounts was an excellent gun.

For all of their emphasis on airpower Japanese Cruiser AA was pretty pathetic. It was also a bit wasteful as instead of accepting the loss of torpedo armament (or even the spare torpedoes) and just using the best AA guns they had they kept trying new guns but only mounting 4 on the Agano's didn't do much.
The Agano's were going in too many different directions at the same time.

If you have perfect air superiority you don't need AA!

Was fire control the big thing that was missing for Japanese AA, or was it just they had relatively few guns compared to the USN? They had the 127mm Type 89 which perhaps wasn't up to par with the US 5"/38, but it seems to have been Ok. And later they introduced the 100mm AA gun, which seems to have been excellent, although it was so late it wasn't introduced in particularly large numbers before the US juggernaut steamrolled them.

For bigger ships, the insistence of a separate surface secondary battery and a separate heavy AA instead of DP mounts was arguably, in retrospect, a mistake.

Perhaps the larger gap was in light and medium AA. Some of their ships had pom-poms, which weren't as good as the 40mm Bofors, in newer designs being replaced with the POS 25mm AA gun.

 

[SaparotRob]

The IJN carriers also had poorly positioned AA batteries, especially Akagi and Kaga.

 

[RCAFson]

Land-based artillery in the modern era has pretty much standardized on the 6" size, as that's about the largest shell that can be manhandled if necessary, and also that's about the maximum size of a gun that can be installed on a SP platform, provide some splinter protection for the crew, and still be road mobile.

For sea-based artillery conditions are more cramped, and the platform is moving and pitching, moving the maximum size that can be manhandled downwards. Consensus seems to be that somewhere around 5" is the maximum that can be manhandled in a somewhat sustained fashion without tiring the gun crews too fast.



Yes, the Brits waffled around with a number of different guns in this class until they developed and then standardized on the 4.5", which by all accounts was an excellent gun.



If you have perfect air superiority you don't need AA!

Was fire control the big thing that was missing for Japanese AA, or was it just they had relatively few guns compared to the USN? They had the 127mm Type 89 which perhaps wasn't up to par with the US 5"/38, but it seems to have been Ok. And later they introduced the 100mm AA gun, which seems to have been excellent, although it was so late it wasn't introduced in particularly large numbers before the US juggernaut steamrolled them.

For bigger ships, the insistence of a separate surface secondary battery and a separate heavy AA instead of DP mounts was arguably, in retrospect, a mistake.

Perhaps the larger gap was in light and medium AA. Some of their ships had pom-poms, which weren't as good as the 40mm Bofors, in newer designs being replaced with the POS 25mm AA gun.

All naval 6in guns had hand loaded or transferred shells, and naval 6in guns had a higher rate of fire than land based artillery. The USN 5in/25 had a fixed cartridge as did the RN 4.5in and they weighed 74lb and ~90lb, yet both were able to achieve a sustained 12RPM or better. The RN 5.25in shell was 80lb and it had a separate cartridge.

If you read Lundstrom's 3 volumes on the war in the Pacific (First Team 1 and 2 and Black Shoe carrier Admiral) you'll find that naval AA was ineffective on both sides (but the IJN was worse) and it wasn't till the introduction of massed 20 and 40mm guns in the USN at Santa Cruz that AA got really lethal.

 

[EwenS]

All naval 6in guns had hand loaded or transferred shells, and naval 6in guns had a higher rate of fire than land based artillery. The USN 5in/25 had a fixed cartridge as did the RN 4.5in and they weighed 74lb and ~90lb, yet both were able to achieve a sustained 12RPM or better. The RN 5.25in shell was 80lb and it had a separate cartridge.

If you read Lundstrom's 3 volumes on the war in the Pacific (First Team 1 and 2 and Black Shoe carrier Admiral) you'll find that naval AA was ineffective on both sides (but the IJN was worse) and it wasn't till the introduction of massed 20 and 40mm guns in the USN at Santa Cruz that AA got really lethal.

're RN 4.5", it depends on which Mount/ turret you are referring to.

Single Mk V in destroyers (Savage and Z/C clases) used separate shell and cartridge cases, as did the guns in the twin Mk.IV turret in Savage & the Battle class. So did the post war turrets in the carriers Ark Royal IV & Eagle.

The earlier Mk.II BD (Between Deck) turret in battleships and carriers and the Mk.III UD (Upper Deck) mount in Ark Royal iii and depot ships used fixed rounds.

 

[Shortround6]

Was fire control the big thing that was missing for Japanese AA, or was it just they had relatively few guns compared to the USN? They had the 127mm Type 89 which perhaps wasn't up to par with the US 5"/38, but it seems to have been Ok.

The fire control was a different story. But the old light Cruisers and the destroyers early had no AA fire control or very rudimentary. larger/newer ships had better fire control.
Problem for the Japanese was both the scale of issue (very rarely more than 8 guns per ship) and the rate of fire, roughly 66% that of the US 5"/38 but then the 5"/38 was the best in the world for AA at that time.

And later they introduced the 100mm AA gun, which seems to have been excellent,

It was technically excellent, but it came with problems. Guns of that veleocity level wore out their guns tubes quickly. The extra velocity/vertical range wasn't really that useful, nobody was level bombing from 30,000ft or above against ships. The long/ heavy barrels required a bigger/ more powerful mounting. The 100mm AA gun twin mount didn't turn or elevate much quicker than the twin 5"/38 and weighed almost the same and fired at about the same rate of fire. Trouble was it was firing 29lb shells and not 54-55lb shells.
And just 7 ships showed up with them before 1944.

Perhaps the larger gap was in light and medium AA. Some of their ships had pom-poms, which weren't as good as the 40mm Bofors, in newer designs being replaced with the POS 25mm AA gun.

Few, if any, of the 2pdr pom-pom guns served in WW I aboard ship.

The POS 25mm gun was few in number in the beginning of the war and was supplemented by the almost as POS 13mm Machine gun.

Now the Problem for the Japanese was that their standard destroyer 5in gun was a POS as an AA gun which meant that bulk of the under 8in cruiser ships were depending on a sprinkling of 25mm and 13mm guns. Note that a number of their large Destroyers had one large 5in mount replaced by the 5in type 89 to improve AA capability, much like some of the Tribal's replaced one of the twin 4.7in mounts with a twin 4in AA mount.
Some of the older Japanese light cruisers landed their 3in AA guns for two extra triple 25mm mounts (total of 4?). Most of the time there were bigger targets to attract the Allied planes.

 

[RCAFson]

're RN 4.5", it depends on which Mount/ turret you are referring to.

Single Mk V in destroyers (Savage and Z/C clases) used separate shell and cartridge cases, as did the guns in the twin Mk.IV turret in Savage & the Battle class. So did the post war turrets in the carriers Ark Royal IV & Eagle.

The earlier Mk.II BD (Between Deck) turret in battleships and carriers and the Mk.III UD (Upper Deck) mount in Ark Royal iii and depot ships used fixed rounds.

I meant the early war 4.5in UD and BD twin mount, using the fixed cartridge as they served a similar role as the 5.25in mounts on the Dido and KGV class ships.

 

[RCAFson]

RN gunnery radar:


View: https://youtu.be/t-fJ255jMH4

The above film is from 1943/44, but would be applicable to the most modern radars in late 1941.

 

[Reluctant Poster]

Thanks, that is probably the one. It seems the IJN tactics held sway through most of 1942 and the USN
counter tactics proved to be superior from 1943 on.

The IJN was still winning as late as July 1943. It wasn't until the Battle of Vella Gulf in August that the USN tactics finally started to work. Note that the use of cruisers was abandoned. The so called machine gun cruiser tactics were a flop. Helena was lost and St Louis and Honolulu were put out of action for several months. In mid 1943 the USN gave up on continuous fire and copied the RN method of salvo firing.

 

[Admiral Beez]

https://www.armouredcarriers.com/

KEY POINTS TO CONSIDER
1) HMS Ark Royal (91) was designed to operate in the open waters of the Pacific, as Japan was seen as the greatest threat to the Empire in the early 1930s. Therefore it has more similarity in concept to the US carriers than the later Illustrious type carriers.

If the above is accurate, I must wonder if the Air Ministry took a look at what the IJNAS was flying between 1937-1938 when HMS Ark Royal was launched and commissioned. The Mitsubishi A5M introduced a year earlier in 1936 and the Nakajima B5N first flown in Jan 1937 were vastly superior to the fighters and torpedo-bombers being prepared for HMS Ark Royal's CAG. To be fair, the Skua was the better dive bomber until the Aichi D3A enters service in Jan 1940. I'd like to think that had the FAA regained control over its aircraft design and procurement five or more years before 1939 that the aircraft might have been better, but maybe not.

 

[Admiral Beez]

The IJN was still winning as late as July 1943...

IDK. Here's IJN losses up to June 1943. Just turn off your volume first - the music is ridiculous.


View: https://youtu.be/-pRun6GNlQM?si=Z7BysxZ6psJ1hF2J&t=76

In just eighteen months after Pearl Harbor, the IJN's losses include 3 battleships, 6 carriers, 4 CAs, 2 CLs, 36 destroyers and 29 submarines.

If this is still winning, what does losing look like?

 

[Wild_Bill_Kelso]

The IJN was still winning as late as July 1943. It wasn't until the Battle of Vella Gulf in August that the USN tactics finally started to work. Note that the use of cruisers was abandoned. The so called machine gun cruiser tactics were a flop. Helena was lost and St Louis and Honolulu were put out of action for several months. In mid 1943 the USN gave up on continuous fire and copied the RN method of salvo firing.

I think that is a bit delusional and very much overstating the case. Japan was winning until Midway. From that point on it was roughly even for a few months, until the battles of Milne Bay (Aug-Sept 1942), the Naval battle of Guadalcanal (Nov 1942), and the completion of the Guadalcanal Campaign by February 1943. Cruisers were still being used until the end of the war.

And as we have discussed, at length, on this forum, but it clearly bears repeating, unlike the USN, the RN was hopelessly outmatched by the IJN.

 

[Admiral Beez]

Unlike the USN, the RN was hopelessly outmatched by the IJN.

True. If the ETO and MTO were not so demanding of ships, the RN's submarines would be very useful against the IJN. Put a dozen RN boats between FIC and Malaya and another doze split between Sarawak and Penang, all with effective ROE, and the IJN's inept ASW should see much of their invasion fleet sunk.

 

[Reluctant Poster]

I think that is a bit delusional and very much overstating the case. Japan was winning until Midway. From that point on it was roughly even for a few months, until the battles of Milne Bay (Aug-Sept 1942), the Naval battle of Guadalcanal (Nov 1942), and the completion of the Guadalcanal Campaign by February 1943. Cruisers were still being used until the end of the war.

And as we have discussed, at length, on this forum, but it clearly bears repeating, unlike the USN, the RN was hopelessly outmatched by the IJN.

I was speaking specifically about surface actions at night. That was the subject which started with torpedoes. The majority of Japanese losses were to aircraft and submarines.

 

[Reluctant Poster]

IDK. Here's IJN losses up to June 1943. Just turn off your volume first - the music is ridiculous.


View: https://youtu.be/-pRun6GNlQM?si=Z7BysxZ6psJ1hF2J&t=76

In just eighteen months after Pearl Harbor, the IJN's losses include 3 battleships, 6 carriers, 4 CAs, 2 CLs, 36 destroyers and 29 submarines.

If this is still winning, what does losing look like?

I never said they were winning overall. They were winning most of the night fighting. The list of warships at the bottom of iron bottom sound is mostly American.

Ironbottom Sound - Wikipedia

en.wikipedia.org

 

[Shortround6]

unlike the USN, the RN was hopelessly outmatched by the IJN.

Well, we are over 30 pages and 630 posts into this discussion.

The RN (and Commonwealth) in actual history was fighting very, very out numbered, poorly supplied and pretty much lacking in air cover/support.

Which would go badly for any navy.

In a what if scenario with better air cover/support, better supply and more numbers a lot of mismatch goes away.

However the match up would not be RN substitutes for USN situation, at least not if the RN has at least some combat experience.
The RNs strengths are not the same as the USN strengths and the RN weaknesses are not the USN weaknesses.

With 15-20 RN subs at the start that entire aspect of the naval war gets flipped. Japanese losses due to submarines goes way up (British torpedoes worked).
Night actions get somewhat turned around. Again British torpedoes worked, British had more experience with radar/night fighting than the USN did. Enough better or equal to the IJN???

Large carrier battles?
British loose.

Big daylight BB action?
British don't engage (they aren't going to have the numbers unless the war in Europe is very different).

Amount of British air cover/support???
A big hinge point. If the initial Japanese attacks do not go well they get sucked into a sort of Guadalcanal battle of attrition only in the western DEI/Singapore area sooner than Guadalcanal.

British also get sucked into the same sort of battle, trying to keep land forces supplied in Malaysia and much of the southern DEI. IJA is still somewhat stuck in China.
If the British can get more resources into Burma before the fight starts the British may be able to hold Burma (mosty) and keep the Burma road open.

Japanese subs can attack the British supply lines in the Indian Ocean. However the British are better at ASW than the Japanese. It will take a while but the Japanese cannot replace losses as well.


Lets look at the basics. The world's navies were set up on the famous 5 : 5 : 3 : 3 : 3 ratio. This scenario has the US (5) sitting it out and with it the US bases in the Pacific, which the Japanese cannot use.
German surface fleet is somewhere between 1 and 2. If Norway happened as historically Germany is barely at 1.
Without the defeat-surrender of France, Italy and France pretty much cancel each other out.

Without a lot of war losses and the need to ride herd on the Italian and German navies the British can out number the Japanese in just about every catagory except carriers.

How much strength does the RN need to hold Burma, Malaya, Singapore and the DEI and get the IJN into a war of attrition that the Japanese cannot win?

 

[Admiral Beez]

If we can get Weimar to work (keeping Stresemann alive might just do it) and keep Mussolini in check, the Japanese will be facing much of the RN. Though with a lessor threat of Germany between the wars, what does the RN look like?

 

[SaparotRob]

With little scholarly research, I would say the RN would have been a nasty surprise to the IJN. Especially at night.

 

[Shortround6]

Though with a lessor threat of Germany between the wars, what does the RN look like?

The Thing is that the German navy was pretty of much of a minor blip for most of the 1930s.

Even the Scharnhorst and Gneisenau are not going to cause a major change in RN policy.
The British are going to order at least some KGVs just because the R class is too old and due for replacement. Same can be said for much of the 1930s building program. RN wanted to be able to deal with both the Italians and Japanese at the same time if France stayed out of a potential war. Since it took 4-6 years to build a class of battleships (or 4-6 large carriers) fleet planning was long term while political alliances could change quicker than ships could be built. They were going to build the new ships and then scrap the old ones depending on the political situation. WW I leftovers (BB or Cruisers and Destroyers) wear out and need refitting/rebuilding. Depending on the rebuilds, new ships aren't that much more expensive and you start with a new ship and not rebuilds for the 15-20 years.

The Italians had 4 BBs in the early 30s and rebuilt 2 of them from 33-37, then they rebuilt the other 2 from 37-40. They laid down 2 new ones in 1934 and the last two new ones in 1938 so the as far as big ships go the Italians were upgrading their fleet a lot faster than the Germans were from 1934 on. The Italians had built 7 8in cruisers before 1933 and built 12 modern 6 in cruisers starting in 1928 and finishing the last in 1937.

In fact between 1923 and 1933 Italy had laid down 18 cruisers, 36 destroyers and 49 submarines. The world wide depression slowed warship construction considerably in 1932-36.
Germany only becomes a factor in the very late 30s.

 

[RCAFson]

https://www.armouredcarriers.com/

KEY POINTS TO CONSIDER
1) HMS Ark Royal (91) was designed to operate in the open waters of the Pacific, as Japan was seen as the greatest threat to the Empire in the early 1930s. Therefore it has more similarity in concept to the US carriers than the later Illustrious type carriers.

If the above is accurate, I must wonder if the Air Ministry took a look at what the IJNAS was flying between 1937-1938 when HMS Ark Royal was launched and commissioned. The Mitsubishi A5M introduced a year earlier in 1936 and the Nakajima B5N first flown in Jan 1937 were vastly superior to the fighters and torpedo-bombers being prepared for HMS Ark Royal's CAG. To be fair, the Skua was the better dive bomber until the Aichi D3A enters service in Jan 1940. I'd like to think that had the FAA regained control over its aircraft design and procurement five or more years before 1939 that the aircraft might have been better, but maybe not.

The B5N1 would not have been useful to the FAA as it was somewhat underpowered and was not stressed for divebombing, and I don't think the A5M was really up the task as a fighter in the ETO, as it was really under armed.

 

[Admiral Beez]

I don't think the A5M was really up the task as a fighter in the ETO, as it was really under armed.

True. But if Ark Royal was designed to fight Japan in the IPTO, it would be good to consider the aircraft Japan was using and had in development. The only fighter envisioned for Ark Royal seems to be the Skua, which while having four .303 mgs vs. the A5M's two, does not seem like a competitive match. And the Skua is significantly slower than the B5N and the IJN's Bettys and Nells. Not a good fleet defence fighter, but there's no folding-wing fighter from the British that can fit down Ark's narrow lifts until the Fulmar and later Seafire. Fulmar vs. Zero, poor bastards in the FAA fighter.