In an ATL where Japan confines itself to China or secures a negotiated settlement with the Western powers sometime 1931-41.
IJN carrier development without WW2?
- Thread starter RogueBeaver
- Start date
The IJN will still have to assume that it will face the USN at some point so carrier development would follow its otl course. The war in Europe will show the benefit of Armoured flight decks and the vulnerability of the Battleship so armoured carriers will appear and the last Yamato will still be completed as a carrier. No IJA escort carriers (or submarines) and the shadow carrier ships are left unconverted.
One possibility is that Japan does not withdraw from the Treaties, less likely they remain in the LON, but if they accept numerical inferiority to either the RN or USN and instead assume they can pursue technical superiority then I think it is a huge shift in mindset. I think the later course hastens Japan's economic woes, so it seems smarter to let the Treaties constrain opponents who can up build you. Even if they leave the Treaties they will pursue superior ships unfettered by ship tonnage limitations. In the former scenario I think one sees every advantage pursued in the limitations, in the later I think you see larger ships.
Without the war in the Pacific I think the battleship holds its place as "the" weapon longer, but I firmly believe that in both the USN and IJN it was becoming obvious that the battleship was being eclipsed by the carrier for its ability to project damage at range and speed, the naval gun had reached its upper limits, as the next generation of aircraft came into service, especially on larger carriers, it will be the carrier that becomes the foremost capital ship by the end of the 1940s. I think the big guns had a little more life in the Atlantic and even the Med since aircraft will take a little longer to evolve better all-weather capability and in the Med one might still see many assumptions about land-based air power negating the carrier as a strike platform but its fighters should see a sharp rise in importance. That means the RN stays its course and develops armored carriers with smaller air groups. The IJN, like the USN, likely pursues bigger air groups with larger strike aircraft complements, more capability in its aircraft overall, all push up carrier size.
The IJN as far as I can tell relied more on force of personality and combat experience to drive innovation, it seems to lack more formal institutions, so that is the wild card. I think the Japanese pursue the aircraft "carrier" submarine as a stealth raider / "cruiser", but the sub arm should remain committed to striking the enemy fleet. The big gap is electronics, the Japanese need to develop radar and sensors, if they do not get serious about it they may remain technically deficient in that realm longer. Without fighting the USN they may not appreciate the problem until they get trapped playing catch-up, relying too heavily on traditional skills in things like night fighting.
The Japanese had a better land-based naval air arm and better doctrine, I think they continue that, and they had excellent sea planes, another area they will develop out. Japan has a thinner industrial base, it played its hand well up to the eve of war, here they need to jump past the 1,000 HP base line engine and pursue the 2,000+ HP, and of course we do not know when jet engines appear but I suspect they get caught a generation behind there too.
Without the war in the Pacific I think the battleship holds its place as "the" weapon longer, but I firmly believe that in both the USN and IJN it was becoming obvious that the battleship was being eclipsed by the carrier for its ability to project damage at range and speed, the naval gun had reached its upper limits, as the next generation of aircraft came into service, especially on larger carriers, it will be the carrier that becomes the foremost capital ship by the end of the 1940s. I think the big guns had a little more life in the Atlantic and even the Med since aircraft will take a little longer to evolve better all-weather capability and in the Med one might still see many assumptions about land-based air power negating the carrier as a strike platform but its fighters should see a sharp rise in importance. That means the RN stays its course and develops armored carriers with smaller air groups. The IJN, like the USN, likely pursues bigger air groups with larger strike aircraft complements, more capability in its aircraft overall, all push up carrier size.
The IJN as far as I can tell relied more on force of personality and combat experience to drive innovation, it seems to lack more formal institutions, so that is the wild card. I think the Japanese pursue the aircraft "carrier" submarine as a stealth raider / "cruiser", but the sub arm should remain committed to striking the enemy fleet. The big gap is electronics, the Japanese need to develop radar and sensors, if they do not get serious about it they may remain technically deficient in that realm longer. Without fighting the USN they may not appreciate the problem until they get trapped playing catch-up, relying too heavily on traditional skills in things like night fighting.
The Japanese had a better land-based naval air arm and better doctrine, I think they continue that, and they had excellent sea planes, another area they will develop out. Japan has a thinner industrial base, it played its hand well up to the eve of war, here they need to jump past the 1,000 HP base line engine and pursue the 2,000+ HP, and of course we do not know when jet engines appear but I suspect they get caught a generation behind there too.
The Taiho points to where IJN carrier design was headed; and it's likely where they go, substantially, even with a robust P.O.D. earlier in the 30's. It might just not have all the lessons drawn from combat against the USN (especially as regards damage control). The IJN knows it will never be able to match numbers with the United States (let alone the United States plus Great Britain), so it knows it needs carriers with more capability, and more survivability, even as it struggles to figure out how to make those work.
So I would expect the general pattern set by Taiho to be where the IJN goes in the 40's and 50's, at least. The hodgepodge of ocean liner and other conversions only happens if there's a fear of imminent war.
The other thing is that even a Japanese detente with the West in the late 30's is unlikely to change much in Europe, so when France falls in 1940, you're still going to see a buildup of the RN, and the Two Ocean Navy Act happening. Japan's decisions will have to react to that from 1940 onward. They will be facing an RN and USN that now substantially outnumber then, even in carrier decks and planes, without the ability to keep up in quantity.
So I would expect the general pattern set by Taiho to be where the IJN goes in the 40's and 50's, at least. The hodgepodge of ocean liner and other conversions only happens if there's a fear of imminent war.
The other thing is that even a Japanese detente with the West in the late 30's is unlikely to change much in Europe, so when France falls in 1940, you're still going to see a buildup of the RN, and the Two Ocean Navy Act happening. Japan's decisions will have to react to that from 1940 onward. They will be facing an RN and USN that now substantially outnumber then, even in carrier decks and planes, without the ability to keep up in quantity.
Would the Shadow Fleet (Junyo/Hiyo) exist? The same for Seaplane and Midget Sub tenders that could be converted into carriers in an emergency (Chitose/Chiyoda)? Junyo was too slow and Chitose too small, bigger carriers like Soryu were the way to go.
Wasn't Taiho a product of wartime experience?
Wasn't Taiho a product of wartime experience?
In part. Her basic design was that of a modified Shokaku, and that was worked out in 1939-41. She was laid down five months before the war began. Some modifications were made during construction.
Interestingly, radar was moved into the mix even before the war broke out, thanks to some information sharing with Germany in 1941.
My sense is that it represents broad reasonable expectations the IJN would develop: bigger carriers, more survivable - the kinds of things needed to counter navies able to build in greater quantity. Similar to the mindset you see at work in the Yamato class, on a more modest scale.
The Taiho was planned even before the war as the basis for an even more ambitious class of fleet carriers, the G-15 project - something that should be looked at for anyone serious about unpacking this question.
What happens in the west? I think not knowing what happens in Europe is simply too important to make accurate predictions?
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If it's on OTL the US cranks out half a dozen Essex class vessels and a number of fast battleships and out numbers Japa. depending on how post war goes the US may keep on
Well no massive 2 Ocean Navy Act probably substantial defense buildup thanks to the fall of France and You still got Carl Vinson in Congress so the USN is still materially and technologically superior in the Pacific.