IJN Soryu's and USS Wasp's Durability and Usefulness

[Kantai Kessen]

Hiyo, Junyo, and the light carriers were organized into essentially separate task groups from the fleet carriers post-Midway - and at both Philippine Sea and Santa Cruz the battleships, Kongos included, were supporting the smaller, slower carriers, not the fast fleet carriers. This was due to their penchant for posting the battleships, along with heavy cruisers, in an Advance Force deployed ahead of the fleet carriers that could soak up attacks and potentially engage in surface actions - that sort of setup would have likely forced Spruance to retire at Midway, for example, rather than stick around and keep bombing things.

Also, knowing how the Japanese - and in fact literally everyone else - organized their light carrier air wings it's highly unlikely that Soryu would go with all dive bombers for her strike complement. They will want to fit torpedo planes, especially since the Japanese preferred to land torpedo planes when they reorganized the carrier air wings to fit more fighters, probably because dive bombers were more useful for attacking aircraft carriers. I'd expect Shokaku and Zuikaku to keep their 27/27/18 ratio, while Soryu's would probably look more like 33 Zeroes, 9 Judys, and 18 Kates, if the goal is to fit more fighters and put up the strike numbers you cited.

36 Zeroes, surely? But otherwise I agree. Kates are more versatile and can be used for land strike.

Nagato and Mutsu as AA escorts?

 

[Kantai Kessen]

Thank you.

Midway. Or Eastern Solomons.

Since Hara did not play well with others and Noyes was too junior and also did not play well with others, this is kind of a political problem within the respective high commands. I would have to be convinced as to how this matchup would be arranged in the overall matrix. If it could be arranged, then it is likely a Kincaid vs. Nagumo type situation with a Halsey vs Kondo topper over that. I would expect indecision and confusion at the top, confusion at the bottom and angry frustration in the middle.

Outcome would depend on how much Hara could get Kondo to listen and whether or not Noyes could be overruled by George Murray. My money would be on Murray.

George Murray?

 

[McPherson]

George Murray?

USS Enterprise; then U.S. Naval Air Forces, Pacific Fleet.

He was the go-to for USNAS air tactics.

 

[CV12Hornet]

36 Zeroes, surely? But otherwise I agree. Kates are more versatile and can be used for land strike.

Nagato and Mutsu as AA escorts?

Soryu and Hiryu never fit more than 60 operational aircraft. 33 is the only way to fit the necessary strike numbers.

Perhaps. Kondo's advance force at Eastern Solomons nominally included Mutsu, but she was left behind because she couldn't keep up with the CAs of the Advance Force and Hiyo and Junyo weren't participating in that op. Thereafter she was left behind in Truk, even when Hiyo and Junyo were finally committed, due to fuel issues. Even with Soryu I doubt the Nagatos will get much of a chance to do anything during the Guadalcanal campaign.

After that, well, any semblance of fixed organization disintegrated for much of 1943. It wasn't until Philippine Sea that things get properly reorganized and Nagato was assigned there to escort Hiyo, Junyo, and Ryuho.

 

[Kantai Kessen]

Soryu and Hiryu never fit more than 60 operational aircraft. 33 is the only way to fit the necessary strike numbers.

Perhaps. Kondo's advance force at Eastern Solomons nominally included Mutsu, but she was left behind because she couldn't keep up with the CAs of the Advance Force and Hiyo and Junyo weren't participating in that op. Thereafter she was left behind in Truk, even when Hiyo and Junyo were finally committed, due to fuel issues. Even with Soryu I doubt the Nagatos will get much of a chance to do anything during the Guadalcanal campaign.

After that, well, any semblance of fixed organization disintegrated for much of 1943. It wasn't until Philippine Sea that things get properly reorganized and Nagato was assigned there to escort Hiyo, Junyo, and Ryuho.

Then perhaps I could modify Soryu's air group to 36 Zeroes, 6 Judys and 18 Kates. This keeps the CAP numbers while leaving 2 Judys for air recon; with the 4 floatplanes apiece that Tone and Chikuma support, and floatplanes from other cruisers or land-based air, this should allow for pretty comprehensive searching.

One interesting thing I notice about Santa Cruz, where Junyo was part of Kondo's Advance Force (and Hiyo should and would have been there if not for her engine room fire earlier), is that the battleships assigned to that force were the fast Kongo and Haruna under RAdm Takeo Kurita, escorted by Isuzu and DesRon2 (commanded by the genius RAdm Raizo Tanaka). Hiei and Kirishima, under RAdm Hiroaki Abe (he who screwed up 1st Guadalcanal) were in the Vanguard Group, along with Nagara and DesRon 10 (under RAdm Susumu Kimura).

I think that Nagato and Mutsu should have been assigned to the Advance Force instead due to their similar speed with the Falcons - they would have used a similar quantity of fuel as the Kongos anyway, operating at that speed, and this is 1942 so the IJN is not yet scraping the bottom of the barrel for every last scrap of NEI and Philippine crude.

Instead I would have kept Kurita's ships in reserve for use in bombardments of Henderson Field, which they had done successfully earlier that month on 13 October in company with Isuzu and Tanaka's destroyers. I would have sent them in ahead of the November convoy instead of Abe with Hiei and Kirishima, as Kurita would actually have had experience of the whole night bombardment lark. I have the impression that Kurita was a better admiral than Abe, and thus he would have done a better job even when faced with unexpected US opposition. That aside, Tanaka would also demolish the US destroyer force and thus definitely help Japan's prospects.

That's besides the main point of this discussion but it is an interesting idea.

EDIT: Kurita became VAdm in May 1942. More senior than Abe, so more suitable?

 

[Kantai Kessen]

In a hypothetical battle Soryu vs USS Wasp it will come to who will score the first hits and in this case USS Wasp lacked an experienced airgroup, which basically had no, or at best minor combat experience, versus a veteran airgroup on Soryu, with much more experience in especially anti shipping tactics. Equally USS Wasp did have a slight advantage in a slightly thicker belt and more concentrated deckprotection on her engine and boiler rooms, though it left larger parts completely unprotected as a result due to weight saving measures. One of her biggest flaws was her absence of any reliable form of underwater protection, also due to weight restrictions.

Basically Soryu, with her more experienced aviators will most likely get the upper hand in the fight, if she was able to strike first, something seriously possible as her aircraft outranged the ones on US Wasp. Coupled with USS Wasp not having the desired AA on her own, she either had to rely on her own fighters to protect her mainly, as well as other escorting warships, which in august 1942 was still not as good as it would be a few years later. (although significantly better than the AA on their opponents still.) USN aircraft control, especially fightercontrol was still in its infancy and basically not existing in this time, with the result the fighters did not provide the sort of defense they could have given later on, when more discipline was forced in the heads of the fighter pilots. Japanese pilots at this time were very disciplined and could operate with more primitive means more effectively than their contemporary USN aviators. So the air battle goes to the Japanese most likely.

As spoken US Wasp was not well protected against underwater damage, so she might survive some bomb hits, but not torpedoes put in her hull, unless very fortunate in a part of the hull outside the sections in the center of her hull, such as the tip of her bow, or extreme stern. Soryu was not much better off either, being equally leightweight in construction with just some splinterprotection basically on her vitals, defective internal fuelsystems and the famously inefficient damagecontrolparties. So Soryu could perhaps survive a few bombs on the ends of the ship, but would suffer major, or even catastrophic damage when hit in the center. (By bombs especially as the USN torpedoes were still horribly bad and more often failed to function, then doing their supposed job.)

So the theoretical fight (escorts and other factors excluded as a force on their own):
Soryu gets her search advantage due to her longer ranging aircraft (even the floatplanes on cruisers had a longer range then the USN CV borne aircraft at this time.) USS Wasp detects the enemy scout and prepares for the fight, not knowing yet where her enemy is. CAP is launched, ship prepared for damage and fuelsystems filled with CO2 gas. In the meantime her own scouts are searching for the enemy still, which is out of range still. Soryu strikes with a well coordinated compact strikegroups of around half her full airwing with equal numbers in fighters, divebombers and torpedobombers. (a grouping of 12 + 12 + 12 is a possibility) The CAP of the USS Wasp engages, but the constant chatter and screaming of exited pilots prevents normal communication and the F4F's go for individual targets, mostly the enemy fighters with challenge the USN fighters into dogfights. So the fightercover is not doing its job as expected. The strikplanes get on the USN taskgroup mostly unmolested and start their coordinated two anvil attack on the Wasp, ignoring the escorts completely. The weak AA at this time manages to shoot down several attackers, but more get through and attack the CV. Wasp gets two bomb hits and takes two torpedoes, with the first doing only moderate damage due to proper damage preventive measures taken before, but the two torpedoes do mortal damage as they knock out the power of the ship completely, leaving it dead and with a severe list in the water. (as happened to her larger halfsister USS Yorktown at Midway)

In the meantime the scouts of Wasp detect the Japanese at the extreme edge of their searchpattern and radio in the contact, but Wasp is in no shape to strike anymore with no power left to get aircraft in the air, as she cannot move into the wind anymore, being a motionless ship now. The severe list is not helping either. The Soryu strike returns to the mothership, about half of the planes lost, or shot up in some way. Before this the second strike, smaller than the first wave is flown off, but can get on the target unopposed as the CAP is gone already, either out of fuel, out of ammunition, or both. Finding an inmobile USS Wasp, some of the strike diverts to other targets, but fail to do much doing so. The rest of the attack, 4 torpedoplanes and 5 divebombers attack the Wasp again, scoring two more bomb- and two more torpedo hits sending the CV to the bottom, after a huge explosion. (Perhaps an internal fire created earlier, or by this attack toughed off a bomb magazine, of less likely a fuelbunker exploded???) The AA barrage of the escorting warships downs two planes, but it is over as Wasp is gone and Soryu is not.

Conclusion:
USS Wasp on its own is not a good option in any circumstance in any CV vs CV fight. In any logical operation USS Wasp at any time needed a second CV to operate with, primarily to lessen the weaknesses of the ship itself, as well as to add something else to shoot at for the enemy, as Wasp was not well build to take serious damage.

Wasp did not have the bad engine layout of the Yorktown-class; she alternated boiler rooms and engine rooms (which should have been done on Hornet as well but the shipbuilders were trying to save money and time so they didn't). She is thus less vulnerable to torpedo hits knocking out all her power and propulsion, AS LONG AS they only cause flooding and don't cause any fires or accompanying explosive damage (I think USN DC is in shape to prevent this from happening, as long the ship is not getting excessively hammered at the same time).

Wasp is flawed, sure, but she is not made of paper. Also, if she is being escorted by, say, Washington, the aggressive IJNAS pilots WILL try to attack the battleship (see Santa Cruz and what happened to South Dakota) - which will divert damage from the carrier.

If this is Soryu pre-Midway, though, I think the dive bombers will tear Wasp a new one. Her Val squadron was GOOD. Afterwards, who knows? They might reconfigure it according to my analysis and make her a fighter and TB carrier instead.

 

[Kantai Kessen]

USS Enterprise; then U.S. Naval Air Forces, Pacific Fleet.

He was the go-to for USNAS air tactics.

What would his flagship be, if he were at Guadalcanal? Still Enterprise, replacing Kincaid?

 

[McPherson]

What would his flagship be, if he were at Guadalcanal? Still Enterprise, replacing Kincaid?

Guadalcanal. Probably CACTUS.

 

[Kantai Kessen]

Guadalcanal. Probably CACTUS.

Oh. Cause I just saw he was at Santa Cruz as CO of TF17, aboard Hornet. Under Kincaid then. Perhaps he could be OTC under Fletcher, in an alternative scenario?

 

[CV12Hornet]

Then perhaps I could modify Soryu's air group to 36 Zeroes, 6 Judys and 18 Kates. This keeps the CAP numbers while leaving 2 Judys for air recon; with the 4 floatplanes apiece that Tone and Chikuma support, and floatplanes from other cruisers or land-based air, this should allow for pretty comprehensive searching.

One interesting thing I notice about Santa Cruz, where Junyo was part of Kondo's Advance Force (and Hiyo should and would have been there if not for her engine room fire earlier), is that the battleships assigned to that force were the fast Kongo and Haruna under RAdm Takeo Kurita, escorted by Isuzu and DesRon2 (commanded by the genius RAdm Raizo Tanaka). Hiei and Kirishima, under RAdm Hiroaki Abe (he who screwed up 1st Guadalcanal) were in the Vanguard Group, along with Nagara and DesRon 10 (under RAdm Susumu Kimura).

I think that Nagato and Mutsu should have been assigned to the Advance Force instead due to their similar speed with the Falcons - they would have used a similar quantity of fuel as the Kongos anyway, operating at that speed, and this is 1942 so the IJN is not yet scraping the bottom of the barrel for every last scrap of NEI and Philippine crude.

Instead I would have kept Kurita's ships in reserve for use in bombardments of Henderson Field, which they had done successfully earlier that month on 13 October in company with Isuzu and Tanaka's destroyers. I would have sent them in ahead of the November convoy instead of Abe with Hiei and Kirishima, as Kurita would actually have had experience of the whole night bombardment lark. I have the impression that Kurita was a better admiral than Abe, and thus he would have done a better job even when faced with unexpected US opposition. That aside, Tanaka would also demolish the US destroyer force and thus definitely help Japan's prospects.

That's besides the main point of this discussion but it is an interesting idea.

EDIT: Kurita became VAdm in May 1942. More senior than Abe, so more suitable?

I've said this before, but the problem is not Japan's national fuel situation. The problem is the local fuel situation at Truk, where there was no oil storage. A large part of the reason Mutsu stayed behind for Santa Cruz was that her bunkers were tapped, alongside Yamato's, to provide fuel for the forces at sea. If Japan wants to have Kongo and Haruna available for another bombardment run then they can't afford to fuel up Mutsu, let alone both Nagato and Mutsu, and send them out to sea.

 

[Spencersj345.346]

I've said this before, but the problem is not Japan's national fuel situation. The problem is the local fuel situation at Truk, where there was no oil storage. A large part of the reason Mutsu stayed behind for Santa Cruz was that her bunkers were tapped, alongside Yamato's, to provide fuel for the forces at sea. If Japan wants to have Kongo and Haruna available for another bombardment run then they can't afford to fuel up Mutsu, let alone both Nagato and Mutsu, and send them out to sea.

You know for all that the IJN was really wanting to use Truk as a major forward base in the Interwar years they all but utterly failed to make it useful as one. And even considering they couldn't do so for quite some time under the treaties they still had over 4 years to do so before they kicked off the war

 

[McPherson]

You know for all that the IJN was really wanting to use Truk as a major forward base in the Interwar years they all but utterly failed to make it useful as one. And even considering they couldn't do so for quite some time under the treaties they still had over 4 years to do so before they kicked off the war

Why store fuel or prepare for its storage forward when the doctrine called for sortie and "glorious battle"?

Warship Graveyard of Chuuk Lagoon | Amusing Planet

Note the oil tankers sunk?

File WW2 Japanese Fuel Tank Natsu Shima Truk Lagoon JPG . Sumber Gambar : commons.wikimedia.org

That is NOT indicative of a fuel farm. It just means there was a fuel tank present at Natsu Shima.

 

[Spencersj345.346]

Why store fuel or prepare for its storage forward when the doctrine called for sortie and "glorious battle"?

Warship Graveyard of Chuuk Lagoon | Amusing Planet

Note the oil tankers sunk?

File WW2 Japanese Fuel Tank Natsu Shima Truk Lagoon JPG . Sumber Gambar : commons.wikimedia.org

That is NOT indicative of a fuel farm. It just means there was a fuel tank present at Natsu Shima.

It still doesn't make sense what with Truk being their main forward staging base for attriting the USN thay they couldn't be bothered to put a floating drydock and some shore facilities for along with a decent supply of fuel and ammo. Although to be fair Truk's geography really didn't favor a major base as compared to say Oahu

 

[McPherson]

It still doesn't make sense what with Truk being their main forward staging base for attriting the USN thay they couldn't be bothered to put a floating drydock and some shore facilities for along with a decent supply of fuel and ammo. Although to be fair Truk's geography really didn't favor a major base as compared to say Oahu

Only a few things to note...

a. A lot of what the IJN did or thought they were doing makes is crazy in post-hoc. But some of their logic does make sense.
b. Why build a fuel farm when an oil tanker can be used in peace and war as a floating fuel dump in a weather protected anchorage? The USN actually used this logic itself when forward basing in the latter half of the Pacific War (Eniwetok Atoll is the example.)
c. Look here.

15+ Truk Wwii, Trend Terbaru
Huge anchorages, multiple berthings. Lots of defendable traffic routes into and out of the weather shelters. Nice deep draft berthing.

HIJMS Mutsu is going to blow up along Japanese battleship row ATL just west of Dubian Island and HIJMS Hyuga is going to be driven aground there after USS Moondragon does her torpedo thing.

Now look at Pearl Harbor.

GIS Research and Map Collection: Maps of Pearl Harbor

What happens to PACFLT; if USS Nevada does not deliberately run aground off Hospital Point, but sinks mid-channel during the Pearl Harbor Raid? NTG.

 

[ShySusan]

What happens to PACFLT; if USS Nevada does not deliberately run aground off Hospital Point, but sinks mid-channel during the Pearl Harbor Raid? NTG.

Which is exactly why she was ordered to run aground instead of continuing her effort to reach the sea

 

[Kantai Kessen]

I've said this before, but the problem is not Japan's national fuel situation. The problem is the local fuel situation at Truk, where there was no oil storage. A large part of the reason Mutsu stayed behind for Santa Cruz was that her bunkers were tapped, alongside Yamato's, to provide fuel for the forces at sea. If Japan wants to have Kongo and Haruna available for another bombardment run then they can't afford to fuel up Mutsu, let alone both Nagato and Mutsu, and send them out to sea.

I guess this is yet another demonstration of the IJN capacity for being very smart and very dumb at the same time. Oh bummer.

If Soryu has to be used, which ships would be left behind at Truk that were present for Eastern Solomons and Santa Cruz OTL? I expect she burns fuel at about the rate of a Mogami or Tone (same type of machinery and similar displacement).

 

[McPherson]

I guess this is yet another demonstration of the IJN capacity for being very smart and very dumb at the same time. Oh bummer.

If Soryu has to be used, which ships would be left behind at Truk that were present for Eastern Solomons and Santa Cruz OTL? I expect she burns fuel at about the rate of a Mogami or Tone (same type of machinery and similar displacement).

Hmmm. Leave behind?

The Yamatos; these are fuel hogs. The Nagatos are too slow. Ise and Hyuga are "iffy" as they were poor AAA ships and not very maneuverable.

Take to the party? Most likely, the Kongos, fast, nimble and have admiral and staff facilities; decent bodyguard and C and C platforms, so these are useful in a CTF. The aviation seaplane cruisers and the most modern of the "fleet destroyers" would be for recon (doctrine) and AAA and bodyguard roles, too.

 

[Kantai Kessen]

Hmmm. Leave behind?

The Yamatos; these are fuel hogs. The Nagatos are too slow. Ise and Hyuga are "iffy" as they were poor AAA ships and not very maneuverable.

Take to the party? Most likely, the Kongos, fast, nimble and have admiral and staff facilities; decent bodyguard and C and C platforms, so these are useful in a CTF. The aviation seaplane cruisers and the most modern of the "fleet destroyers" would be for recon (doctrine) and AAA and bodyguard roles, too.

I completely agree with using the Kongos for carrier escort missions; that is indeed the primary role I would give them. As it happens they are the only capital ships fast enough to keep up with the carriers anyway.

However, I think that they are a bit iffy for the bombardment mission, as demonstrated IOTL for 1st Guadalcanal where Hiei showed herself to be vulnerable to the 8-inch shellfire of US heavy cruisers (IIRC it was a shell from San Francisco that did in her steering gear and thus doomed her to be caught by air attack). If it would at all be possible to send in tougher and more heavily armed battleships with a similar quantity of fuel, I would do it.

If that is not possible, even a substitution of Kongo and Haruna with VAdm Takeo Kurita in place of Hiei and Kirishima with VAdm Hiroaki Abe would, I think, make big changes, as I think Kurita, as a more experienced and more senior admiral who has already carried out one successful bombardment mission, would make a better job of the attack than the rookie Abe. The 1st Guadalcanal brawl left Kirishima in basically an undamaged state and with a good number of San-Shikidan shells aboard. She was very much capable of bombarding Henderson Field if Abe had just decided to push on - which he didn't, despite the near total destruction/incapacitation of the US force (only Helena and Fletcher still operable) as he found himself completely out of his depth.

Putting Kurita in Abe's place, and supposing that Kongo is crippled but Haruna is fine, I can see the latter bombarding the airfield and thus not only ensuring the success of the mission, but saving Kongo as she will only be attacked by planes from Enterprise and is thus more readily and successfully covered by the fighters from Junyo and Rabaul. Furthermore, the critical convoy being escorted by VAdm Gunichi Mikawa and RAdm Raizo Tanaka would be subjected to fewer air attacks and thus reach Guadalcanal in a much more combat-worthy state, which would have massive ramifications for the campaign as a whole.

Also furthermore, a successful bombardment on the first try, would remove the need for a 2nd Guadalcanal re-try, thus saving Haruna AND VAdm Nobutake Kondo's career - which could help a lot in 1944 come the big fleet battles and Leyte Gulf. Kondo was, as you have said, possibly the best of the surface admirals and he got 'Kimmeled' after the Guadalcanal failures. I would have liked him to stick around.

 

[McPherson]

I completely agree with using the Kongos for carrier escort missions; that is indeed the primary role I would give them. As it happens they are the only capital ships fast enough to keep up with the carriers anyway.

True. This is exactly the same reason the British tried to use their battlecruisers as aircraft carrier bodyguard ships.

However, I think that they are a bit iffy for the bombardment mission, as demonstrated IOTL for 1st Guadalcanal where Hiei showed herself to be vulnerable to the 8-inch shellfire of US heavy cruisers (IIRC it was a shell from San Francisco that did in her steering gear and thus doomed her to be caught by air attack). If it would at all be possible to send in tougher and more heavily armed battleships with a similar quantity of fuel, I would do it.

Nothing else in the IJN OOB was fast enough to make the run into and out of the airpower circle of Guadalcanal during a night run into Iron Bottom Sound.

If that is not possible, even a substitution of Kongo and Haruna with VAdm Takeo Kurita in place of Hiei and Kirishima with VAdm Hiroaki Abe would, I think, make big changes, as I think Kurita, as a more experienced and more senior admiral who has already carried out one successful bombardment mission, would make a better job of the attack than the rookie Abe. The 1st Guadalcanal brawl left Kirishima in basically an undamaged state and with a good number of San-Shikidan shells aboard. She was very much capable of bombarding Henderson Field if Abe had just decided to push on - which he didn't, despite the near total destruction/incapacitation of the US force (only Helena and Fletcher still operable) as he found himself completely out of his depth.

Kurita was a cautious man. By any standards, he was not exactly Japanese courageous. Abe was not a coward. I think he would have run for it the moment he bumped into the Americans.

Putting Kurita in Abe's place, and supposing that Kongo is crippled but Haruna is fine, I can see the latter bombarding the airfield and thus not only ensuring the success of the mission, but saving Kongo as she will only be attacked by planes from Enterprise and is thus more readily and successfully covered by the fighters from Junyo and Rabaul. Furthermore, the critical convoy being escorted by VAdm Gunichi Mikawa and RAdm Raizo Tanaka would be subjected to fewer air attacks and thus reach Guadalcanal in a much more combat-worthy state, which would have massive ramifications for the campaign as a whole.

Maybe, but it is probably that he would retreat.

Also furthermore, a successful bombardment on the first try, would remove the need for a 2nd Guadalcanal re-try, thus saving Haruna AND VAdm Nobutake Kondo's career - which could help a lot in 1944 come the big fleet battles and Leyte Gulf. Kondo was, as you have said, possibly the best of the surface admirals and he got 'Kimmeled' after the Guadalcanal failures. I would have liked him to stick around.

Kondo was good. Ozawa was much better for the aircraft battles to be fought; which is why he commanded at Philippine Sea. .

 

[Kantai Kessen]

True. This is exactly the same reason the British tried to use their battlecruisers as aircraft carrier bodyguard ships.

Nothing else in the IJN OOB was fast enough to make the run into and out of the airpower circle of Guadalcanal during a night run into Iron Bottom Sound.

Kurita was a cautious man. By any standards, he was not exactly Japanese courageous. Abe was not a coward. I think he would have run for it the moment he bumped into the Americans.

Maybe, but it is probably that he would retreat.

Kondo was good. Ozawa was much better for the aircraft battles to be fought; which is why he commanded at Philippine Sea. .

It would have been even better for the IJN if the Kongos had better AA to satisfy that role (curse the damn 25mm cannon!), but that's for a different time.

I thought the reason the Kongos were chosen was for reasons of fuel consumption? They were the most fuel-efficient capital ships the Japanese had. IIRC the approach down the Slot before 1st Guadalcanal was made at 18 knots, which is not exactly lightning-fast.

Which admiral would you send down the Slot then? It seems neither Kurita nor Abe will do. Perhaps Kondo goes himself, or Mikawa (with some 8th Fleet cruisers to support - yet more help). If Mikawa comes, I can see Raizo Tanaka and DesRon2 coming along for the ride as well, with DesRon10 being used to escort the transports. That will end in an ugly fashion for Admiral Callaghan/

Speaking of the carriers, I thought that a longer and more protracted campaign around Guadalcanal, thanks to the presence of an extra IJN fleet carrier, would delay events going forward, which would help the IJN come 1944. For example - say that the entire US timetable gets delayed 3 months due to a longer and bloodier fight. Then the push up the Solomons and to the Philippines and Formosa is delayed 3 months, assuming that everything afterwards goes IOTL. So Philippine Sea gets fought in September, which is a bit earlier than when Leyte Gulf would be fought IOTL. By that point, Taiho has been in commission for six months instead of three and thus is a bit more qualified for combat, especially damage control. Additionally, the pilots aboard the other carriers will have time for some more useful training and will all have at least six months' experience - which should help at least a bit.

It is even possible - although I admit this is unlikely - that Yamamoto himself may have a different Solomons itinerary, which leads to a very different Operation Vengeance or perhaps no operation at all. In that case, there is a chance that the mastermind admiral himself lives to fight another day and commands the Combined Fleet in 1944.

Furthermore, if Soryu does not die her IOTL death and survives 1942 (a big if, admittedly), then perhaps Shinano and the Ises would not undergo their crap conversion as they would be less necessary. Battleship Shinano at the least would be helpful in 1944 (rushed construction) as a complement to Yamato and Musashi.

Also, construction of the Unryus would be speeded up. Unryu and Amagi commissioned in August 1944 and they would have been present at Leyte IOTL if their air groups had not been destroyed in the Formosa Air Battle. Katsuragi commissioned in October 1944. If resources are not diverted from their construction to convert the battleships, these three carriers, or at least the first two, could be commissioned and worked-up earlier and thus able to participate in this ATL Philippine Sea.

We'd then have the following IJN worst-case OOB:

• CarDiv1: Taiho (63 planes - ballpark), Shokaku (72 planes), Zuikaku (72 planes)
• CarDiv2: Hiyo (51 planes - as IOTL), Junyo (51 planes), Ryuho (36 planes - after her flight deck extension)
• CarDiv3: Zuiho, Chitose, Chiyoda (each with 30 planes)
• CarDiv5: Soryu, Unryu, Amagi (each with 57 planes, as planbes have gotten larger and these are quite small CVs)

For a total of six proper fleet carriers, two slow fleet carriers and four light carriers, carrying a total of 606 planes instead of the 430 they had IOTL. The US would probably have around 900 planes (at OTL Philippine Sea they had 873: https://en.wikipedia.org/wiki/Philippine_Sea_order_of_battle).

With some conserved land-based air to help out and more time to plan, prepare and train, coupled with Ozawa's exemplary leadership, I can see this ALT Philippine Sea going better for the IJN. Even in the real battle, despite the god awful training and the deadly swarms of Hellcats, some IJNAS planes did get through and came very close to landing hits on some of the US ships. It is not a massive stretch, IMO, to see more damage being done and perhaps even some US ships sunk, instead of the landslide victory that Spruance managed to win IOTL. And if there is a surface action afterwards, which was attempted IOTL by Ozawa as a last-ditch effort, and which may be more whole-hearted this time round, the IJN will be fielding their best surface admiral: Nobutake Kondo.

IMO, the potential butterflies from Soryu being around in late 1942 are large, to put it mildly.