Hybrid aircraft carriers (2 Viewers)

[tomo pauk]

... mostly for the navies that were not RN or USN.

Rest of the navies were either too late with the aircraft carriers for ww2, or were unable to make them fast enough to cover the losses (= IJN), or their aircraft carriers were not up the snuff, or a combination. Ideally, some 60+ percent of the ship lenght should've been devoted for aircraft operation? Big gun turrets - perhaps one each at both bow and stern positions - turrets one atop of another push the flight deck too high up?

(yes, going with the proper carriers was the way to go)

For the Italians, having the hybrids in service might've meant that they are not surprised when RN shows up, since the air arm can provide more aircraft for the recon job, as well as that they can perhaps chase off or kill the RN recon(s). Air defense by perhaps two dozen of fighters per the hybrid ship should also be a boon for them.

For the Japanese - instead of the tiny flight deck on the Ise & Hyuga, make a much bigger reconstruction, leaving only the 1st two turrets, or the 1st and last turret, so greater %-age of the ship is devoted to the aircraft?

 

[Shortround6]

The Japanese were the main enthusiasts of the idea. But it didn't get much traction. A small carrier seems to be a better option.
The only non-Japanese ship that comes to mind was the Swedish Gotland.

She was very small.
A major problem is that it doesn't seem to offer much payback. All of the hybrid ships that made it into service (1 Swedish and 5 Japanese?) operated floatplanes. While they could operated 3-6 times the number of floatplanes than most Cruisers or BB did (and offer better repair/maintenance facilities, fuel) I am not sure that offers quite what the users hoped?
Swedes converted the Gotland to an AA cruiser starting in 1943.

While the Ise & Hyuga could operate as battleships, they were 8 gun battleships which put them at a disadvantage to just about any other BB there was, although strong enough to handle heavy cruisers? If you go down to just 4 heavy guns things are even worse. Even a Renown has a lot more firepower. And 4 big guns vs 8-9 8in guns doesn't look good.
How many 8in hits are a mission kill for the Hybrid?
The Ise & Hyuga with just the forward turrets might have held 40-48 planes? But could that number of float planes really make difference? Great recon but strike and air defense roles are lacking. Granted as a Idea things are rather time dependent. A 40 plane Ise in 1942 with Rufes might have worked. Or an Italian ship in 1940-41 vs Sea Gladiators and Swordfish. Once Martlets and Sea Huirrcanes show up floatplane attack aircraft are in trouble.

 

[ThomasP]

Perhaps the angled flight deck would have been developed sooner?

 

[Frog]

The Lexington Class carriers were some sort of hybrids with their 8'' gun turrets.

 

[tomo pauk]

While the Ise & Hyuga could operate as battleships, they were 8 gun battleships which put them at a disadvantage to just about any other BB there was, although strong enough to handle heavy cruisers? If you go down to just 4 heavy guns things are even worse. Even a Renown has a lot more firepower. And 4 big guns vs 8-9 8in guns doesn't look good.
How many 8in hits are a mission kill for the Hybrid?
The Ise & Hyuga with just the forward turrets might have held 40-48 planes? But could that number of float planes really make difference? Great recon but strike and air defense roles are lacking. Granted as a Idea things are rather time dependent. A 40 plane Ise in 1942 with Rufes might have worked. Or an Italian ship in 1940-41 vs Sea Gladiators and Swordfish. Once Martlets and Sea Huirrcanes show up floatplane attack aircraft are in trouble.

No floatplanes. Zekes and Vals, for starters. To what Renown has no good answer

 

[EwenS]

The Japanese were the main enthusiasts of the idea. But it didn't get much traction. A small carrier seems to be a better option.
The only non-Japanese ship that comes to mind was the Swedish Gotland.
View attachment 811448
She was very small.
A major problem is that it doesn't seem to offer much payback. All of the hybrid ships that made it into service (1 Swedish and 5 Japanese?) operated floatplanes. While they could operated 3-6 times the number of floatplanes than most Cruisers or BB did (and offer better repair/maintenance facilities, fuel) I am not sure that offers quite what the users hoped?
Swedes converted the Gotland to an AA cruiser starting in 1943.

While the Ise & Hyuga could operate as battleships, they were 8 gun battleships which put them at a disadvantage to just about any other BB there was, although strong enough to handle heavy cruisers? If you go down to just 4 heavy guns things are even worse. Even a Renown has a lot more firepower. And 4 big guns vs 8-9 8in guns doesn't look good.
How many 8in hits are a mission kill for the Hybrid?
The Ise & Hyuga with just the forward turrets might have held 40-48 planes? But could that number of float planes really make difference? Great recon but strike and air defense roles are lacking. Granted as a Idea things are rather time dependent. A 40 plane Ise in 1942 with Rufes might have worked. Or an Italian ship in 1940-41 vs Sea Gladiators and Swordfish. Once Martlets and Sea Huirrcanes show up floatplane attack aircraft are in trouble.

As for the IJN I assume that you are referring to Tone class and the reconstructed Mogami from 1943. For the existence of those you need to understand the IJN doctrine for recce, which was different from that of the RN & USN. These vessels were only intended to carry floatplanes. The subject came up elsewhere recently and I posted this:-

"There was a fundamental difference between the USN and IJN naval aviation forces. In the USN the carrier air groups had a Scout squadron whose responsibilty was recce to locate an enemy fleet. While the cruisers and capital ships carried floatplanes their primary role was scouting for those ships and observation to assist with their gunnery.

The IJN intended to hold back all its carrier torpedo and dive bombers until an enemy was located and use them to strike hard. Finding an enemy was a responsibilty exported to the floatplanes on escorting warships. Recce therefore became the primary function of the floatplanes carried by the cruisers. This can be seen in the early war operations of the IJN like Operation C and Midway where the bulk of the recce was carried out by floatplanes with only a couple of Kates allocated from the carriers to assist in the task during some operations.

The IJN increased the number of floatplanes on their cruisers from 2 (Aoba & Myoko) to 3 (Takao & Mogami) to a planned 4 in the earliest proposals for the Tones. This was increased to a planned 6-8 when the design was revised as an "aircraft cruiser" which saw the all the main armament forward (partly to protect the aircraft to be parked aft since there was no hangar). These were intended to be 2-4 E7K2 Alf 3 seat and 4 E8N2 Dave 2 seat biplane recce aircraft. In practice it was found that no more than 5 could be carried and more usually 4 (2 of each type). Later these were replaced by 3 seat Aichi E13A1 and 2 seat Mitsubishi F1M1. The lack of a protective hangar for the larger number of aircraft seems to have been the principal cause for the reduction.

When you look at the deployment of the Tones during the war, it is mostly as escort to the carriers, providing that recce function.

After Midway the IJN came to realise that it did not have enough recce assets supporting the carriers. Hence the decision to reconstruct the already heavily damaged Mogami as an "aircraft cruiser". She was then equipped to carry 11 seaplanes (initially just 4xE13A1 and 3xF1M1. Later the Aichi E16A Paul was intended as the replacement)."

Ise & Hyuga were intended to fulfill a different role. Their hybrid origins lie in the post Midway IJN carrier crisis.

The first steps taken by the IJN post Midway to improve their carrier stock were as follows:-
1. accelerated construction of 15 medium carriers based on Hiryu (more Unryu class with 2 laid down by end of 1942. Unryu and 2 of these 15 completed Aug-Oct 1944) and 5 fleet carriers on a modified Taiho design, (construction not expected to begin until 1944 and was never started).
2. conversion of specially designed ships into their planned light carrier configuration (Chitose & Chiyoda work began Jan 1943 completed Dec 1943 / Jan 1944)
3. conversion of selected emerchant ships to escort carriers (Kaiyo & Shinyo conversions completed Nov 1943)
4. conversion of Warship No 110 to a carrier (Shinano. Reconstruction design process began July 1942 with work commencing early 1943 & completed Nov 1944)

As the above were not expected to produce fruit until 1944 and a quicker solution was sought. Early on Ise & Hyuga were to be the first BB conversions with others to follow. They were intended to fulfill an offensive role. Various proposals for the conversion were made from full carrier, through 2, 3 & 4 turret versions. Eventually towards the end of 1942 the 4 turret version was chosen for speed and the economy of materials and labour required in the reconstruction. The flight deck was intended only for the carrying and launch of aircraft via the two catapults fitted at its forward end, which interfered with use of the two midships turrets. The flight deck was too small to ever envisage the recovery of aircraft onto it.

In initial plans the air group was to comprise only a modified version of the D4Y Judy dive bomber. Fairly quickly it was revised around 18 (+6 reserve) D4Y Judy dive bombers specially modified for catapult launch from a cradle plus 18 (+6 reserve) Aichi E16A Paul recce floatplanes, split equally between the two ships i.e. 12 of each type on each vessel. However the complement of each ship was reduced to 22 (11 of each type) with 9 in the hangar and 13 stowed permanently on flight deck. While the float planes could be recovered by a crane on the aft port edge of the flight deck, the dive bombers that survived would either have to find another proper carrier to land on or a shore base.

Officially work on Ise began in Dec 1942 but other evidence suggests it was Feb 1943. She completed on 5 Sept 1943. Hyuga, which had already lost a turret in an accident prior to Midway, was converted between 2 May 1943 and 30 Nov 1943. Delays crept into the programme due to other repair work.

Due to a shortage of aircraft they couldn't participate in the Battle of the Philippine Sea in June 1944, and then due to their limitations had to be paired up with the regular carriers Junyo & Ryuho to form the 4th Carrier Division. At the end of the day however they only ever embarked a few aircraft for trials, and never operationally.


A final step for the IJN in replacing its lost carriers was the decision to convert the incomplete hull of the cruiser Ibuki into a carrier that was taken in the third quarter of 1943 after her launch.

 

[EwenS]

The Lexington Class carriers were some sort of hybrids with their 8'' gun turrets.

No. They were fitted for purely defensive purposes.

When the Lexingtons were built there was a school of thought that believed that a carrier might in the event of an action at night or in bad weather, when it couldn't fly its aircraft, need to defend itself against enemy cruisers that had avoided, or sunk, its own escorting cruiser force. Interwar the utility of such an armament was hotly debated within the USN with the fliers initially wanting them removed. The matter arose again in 1940/41 when the MIdway class was being designed, by which time even the fliers thought that a "big gun" armament might be a good idea. How much that might have been a reaction to the loss of Glorious in June 1940 has not been recorded.

The reconstruction plans for these ships drawn up in 1938 saw their retention. As late as 1940 Lexington had her guns updated to the latest model while in late 1941 Saratoga received gunnery radars to improve the effectiveness of her battery. It was only in 1942, with the need to save weight on heavily overloaded ships to allow an increase in AA armament, that the decision was taken to remove the 8in battery.

 

[Shortround6]

Nobody ever operated a high speed (relatively) monoplane from an angled fight deck for landing during the time in question.
It was certainly possible to arrester land on a short deck with funnel/s/Bridgework in front 1/4-1/2 of the ship. It is not practical, it either suffers from more crashes (planes that should have been waved off during the approach) or a high wave off rate (planes that are waved off sooner in the approach) to avoid accidents. And/or crash barriers get a more of a workout and you need more replacement planes/crewmen.
Catapult take-offs were certainly possible but time between launches were going to be a bit slow.

The Ise and Hyugo were intended to use D4Ys and E16A, early types of aircraft could be substituted, however the D4Ys were never intended to land back on board, they were supposed to fly (or attempt) to the nearest land base. The E16As could land next to the ship and be hoisted back on board.
Not really a substitute carrier in the accepted sense. A lot of money invested special operation/s ships. Use once (one attack) and then needed , at the very best, to sail to an anchorage that has replacement planes available to be hoisted aboard.

 

[EwenS]

Perhaps the angled flight deck would have been developed sooner?

The USN flying deck cruiser of the 1930s had a straight deck that was angled very slightly to port (about 3 degrees IIRC) to avoid the island. It had zero effect on developing an angled deck.

The oddity that was the Flying Deck Cruiser

Between the end of WWI and the beginning of WWII, the U.S. Navy experimented with several, ultimately spurned, designs to create a hybrid aviation carrier or cruiser carrier– basically a crui…

laststandonzombieisland.com

 

[Shortround6]

As for the IJN I assume that you are referring to Tone class and the reconstructed Mogami from 1943.

I had skipped the reconstructed Mogami but included the Oyodo.

Japanese cruiser Ōyodo - Wikipedia

en.wikipedia.org

Which also shows some of the basic problem, you don't get 2 ships for the price of 1. You get two 1/2 ships for the price of over 100%.

Now part of the problem is that the Japanese were using very large powerplants but compared to the HMS Fiji the Japanese got 1/2 the main battery, less light AA and no torpedoes for 4 extra float planes (3 times the Fiji) on a ship that was about 400-500 tons lighter than the Fiji. They paid for the speed/ 37% more power.

The Oyodo even if built in the late 30s and raiding into the Indian Ocean in 1942 would be hard pressed to defeat anything more powerful than an old WW I D class Cruiser.
It could run from a Leander but it had little or no business trying to gun duel one. Hopefully the Oyodo's floatplanes could spot the British cruiser/s in time for the surface encounter not to take place.

 

[EwenS]

I had skipped the reconstructed Mogami but included the Oyodo.

Japanese cruiser Ōyodo - Wikipedia

en.wikipedia.org

Which also shows some of the basic problem, you don't get 2 ships for the price of 1. You get two 1/2 ships for the price of over 100%.

Now part of the problem is that the Japanese were using very large powerplants but compared to the HMS Fiji the Japanese got 1/2 the main battery, less light AA and no torpedoes for 4 extra float planes (3 times the Fiji) on a ship that was about 400-500 tons lighter than the Fiji. They paid for the speed/ 37% more power.

The Oyodo even if built in the late 30s and raiding into the Indian Ocean in 1942 would be hard pressed to defeat anything more powerful than an old WW I D class Cruiser.
It could run from a Leander but it had little or no business trying to gun duel one. Hopefully the Oyodo's floatplanes could spot the British cruiser/s in time for the surface encounter not to take place.

You need to stop looking at IJN warships through western eyes and comparing them directly with RN/USN warships. The IJN formed its own view interwar about the war it was likely to fight and built and converted ships to meet those expectations. Vessels like the Tones and Oyodo as well as the torpedo cruisers fitted that plan so appear strange to western eyes.

Oyodo was built for a very specific purpose that fitted IJN plans for its decisive battle with the USN as the latter proceeded across the Pacific to relieve the Philippines. The IJN intended to deploy its submarine flotillas to attrite the US fleet with each flotilla needing a flagship.

"For this purpose the flagship of a Submarine Squadron could not remain behind in its advanced base but had to move forward to the vicinity of the enemy in order to be able to provide continuous and accurate information about the strength, position and course of the enemy force and to coordinate the successive assaults of the subordinate forces..... A flagship capable of fulfilling these tasks had to have good mobility (kidosei) and endurance, command facilities which included extensive and long-range communication systems, and the ability to conduct its own reconnaisance" (Hans Lengerer "The IJN Light Cruiser Oyodo" Warship 2018).

He concluded the article as follows:-

"Oyodo was a highly specialised design conceived for a particular sequence planned before the start of the Pacific War. The execution of this operation depended upon the US Navy acting as expected. The forward operation by the IJN submarine squadrons was to have been initiated immediately before the outbreak of the war, but at that stage Oyodo had yet to be launched, and by the time she was completed the Japanese forces were already in retreat..........

In summary, Oyodo owed her existence to the unrealistic strategic and tactical planning of the NGS before the war and to the IJN's adherence to outdated concepts........."

The 1938 IJN requirement for Oyodo (and her intended sister ship Niyodo) was therefore:-

1. Purpose was to replace the 5,500 ton cruisers of the 1920s used as submarine squadron flagships.
2. Displacement 5,000 tons standard (quickly increased to 6,600 tons and later to 8,200 tons)
3. Max speed 36 knots with endurance 10,000nm at 18 knots
4. Armament 8x5in HA guns 18x25mm in twin mounts. TT. Increased to 2x3 155mm removed from the Mogamis in view of possible need to defend themselves against USN cruisers and destroyers with ethe AA armament being based around 4 twin 3.9in weapons and 16 twin 25mm.
5. 6-8 long range high speed seaplanes (eventually 6 with a hangar for 4 was specified). Launched by single 44m compressed air catapult. 10+ hour endurance. scouting range 800+nm. Fast enough to escape then current USN fighters.
6. Extensive communications including underwater signalling and sound detection aparatus.

By the time Oyodo completed in April 1943, the aircraft intended for her (Kawanishi E15K1 Norm) had only reached the prototype stage, and the nature of the war as it turned out was not how Japan had envisaged it pre-war. Plans to convert her to a fleet flagship were then formed with the least drastic being chosen at the end of 1943 which was carried out in March 1944. The hangar was converted to staff accomodation and offices. Better radars fitted. The long catapult was replaced with a gunpowder propelled 19.4m catapult and just 2 Aichi E13A1 Jake foatplanes were carried (1 on the catapult and the other between the catapult and former hangar) and her light AA was heavily augmented.

 

[Shortround6]

You need to stop looking at IJN warships through western eyes and comparing them directly with RN/USN warships. The IJN formed its own view interwar about the war it was likely to fight and built and converted ships to meet those expectations. Vessels like the Tones and Oyodo as well as the torpedo cruisers fitted that plan so appear strange to western eyes.

Oyodo was built for a very specific purpose that fitted IJN plans for its decisive battle with the USN as the latter proceeded across the Pacific to relieve the Philippines. The IJN intended to deploy its submarine flotillas to attrite the US fleet with each flotilla needing a flagship.

In summary, Oyodo owed her existence to the unrealistic strategic and tactical planning of the NGS before the war and to the IJN's adherence to outdated concepts........."

Basically the Hybrid ships were outdated concepts. Nothing really wrong with fleet flag ships or even flotilla flag ships. Nothing really bad about designing a flagship to contain command, communications and even a small aviation unit function in the same hull. Problems show up in less than BB sized ships (and they had their own problems) when they want 35kt speeds (surface attack speeds) and surface armament (guns and torpedoes) in a flagship. Either design a modern flagship (command/control/intelligence---command from the rear) or at traditional flagship (lead from front or middle of battle line, or destroyer line depending on class of Flagship).
Japanese seemed to want to do both. At least they didn't want to Oyodo to go in slinging torpedoes in the final battle

The Tones? They wanted everything.

Now the question is such ships would have been useful to anybody else. But we need to have some idea of what the Japanese gave up to get the aircraft compliment and what the aircraft compliment really did and how it could operate (allowing for the fast change in aircraft) and especially looking at what a small carrier could do without the handicap of a Bridge and forward turrets. If you are going to play at long range gunnery you need a high structure to mount the gun director/range finder on and between that and the turrets themselves that kind of stops the straight flight deck, unless you are building really large ships and can offset the guns/fire control to one side of the deck.

 

[tomo pauk]

So we have the shortcomings covered.
Now about the benefits. For the Germans, a hybrid instead of the twins at 1st. Only the front turrets as far as the big guns, rest of the ship (some 63% here, or ~148m - a reason why I've 'measured' the ratios via the pdf viewer) is devoted to the air group.



So perhaps this:



Blue should be the elevators (main and auxiliary). Taking off should be biased towards the left side of the flight deck, in order to miss the super-imposed turret. I haven't went with the extendable flight deck.
The 15cm guns are gone, too, the smaller guns should've been the 10.5cm + the light flak.

Air group - perhaps up to 25 'normal' aircraft, like the Bf 109T and Ju 87C? Should've been providing a good recon beyond the horizon, air defense and dive bombing.

 

[Howard Gibson]

... mostly for the navies that were not RN or USN.

Rest of the navies were either too late with the aircraft carriers for ww2, or were unable to make them fast enough to cover the losses (= IJN), or their aircraft carriers were not up the snuff, or a combination. Ideally, some 60+ percent of the ship lenght should've been devoted for aircraft operation? Big gun turrets - perhaps one each at both bow and stern positions - turrets one atop of another push the flight deck too high up?

Jack of all trades, master of none.

If HMS Glorious had been a composite ship with battleship or heavy cruiser guns, would it have survived contact with the Scharnhorst and Gneisnau? Fairey Swordfish could operate from tiny flight decks. How about functional fighter aircraft?

Did the Italians even try to build a carrier? The Italian navy operated fairly close to Italy, so there was an opportunity to use land based aircraft to patrol around Italian fleets and spot hostile activity. How good was Italian radar? Their fleet faced a double whammy when it came to keeping track of mischief by the Royal Navy. If the Italians build a couple of carriers, what do they not build? Their industrial capacity was limited. It is not good enough to build carriers. You need carrier based aircraft too.

 

[tomo pauk]

If HMS Glorious had been a composite ship with battleship or heavy cruiser guns, would it have survived contact with the Scharnhorst and Gneisnau? Fairey Swordfish could operate from tiny flight decks. How about functional fighter aircraft?

Have I not posted this disclaimer in the 1st post here:

... mostly for the navies that were not RN or USN.

1 - Did the Italians even try to build a carrier? 2 - The Italian navy operated fairly close to Italy, so there was an opportunity to use land based aircraft to patrol around Italian fleets and spot hostile activity. 3 - How good was Italian radar? 4 - Their fleet faced a double whammy when it came to keeping track of mischief by the Royal Navy. 5 - If the Italians build a couple of carriers, what do they not build? Their industrial capacity was limited. 6 - It is not good enough to build carriers. You need carrier based aircraft too.

(my numeration)

1 - Yes, Italians tried to make one, the Aquila.
2 - Land-based aircraft down't work well when they are hundred of miles away and the needed reaction time is measured in minutes. They are also very bad (from the Navy's PoV) when they are tasked to do something else, and Navy needs them right now. Their time at station is bad, and the ability to do more than one mission a day is very bad, if not impossible to achieve.
3 - It was bad. Even a greater reason to have the organic and sizable air group.
4 - Again, here the carrier-based aircraft are better than the land-based.
5 - They can modify the two old battleships into two hybrid carriers.
6 - Damn. And I was just about to send their carriers in the harm's way without the air groups.

 

[Howard Gibson]

2 - Land-based aircraft down't work well when they are hundred of miles away and the needed reaction time is measured in minutes. They are also very bad (from the Navy's PoV) when they are tasked to do something else, and Navy needs them right now. Their time at station is bad, and the ability to do more than one mission a day is very bad, if not impossible to achieve.

The critical air mission is scouting. Interception is nice, but not necessary (N^3). The Italian fleet needs someone to circle continuously above them to spot approaching British. They had reasonably fast twin engined aircraft, which were fast enough to be difficult for Royal Navy fighters to intercept. The Italians did have seaplanes, but I don't know how safe these would be around RN fighters, when carriers are spotted.

 

[tomo pauk]

The critical air mission is scouting. Interception is nice, but not necessary (N^3). The Italian fleet needs someone to circle continuously above them to spot approaching British.

Interception was necessary at least during the Battle of Cape Matapan, that saw 3 Italian heavy cruisers sunk because the Albacores, their crews and torpedoes were up the snuff. Italians also lost 3 destroyers.
Recons need to circle ahead of the fleet; the more of them, the better.

They had reasonably fast twin engined aircraft, which were fast enough to be difficult for Royal Navy fighters to intercept.

What were these 2-engined aircraft?

 

[Howard Gibson]

What were these 2-engined aircraft?

Sorry, three engined aircraft. Savoia-Marchetti SM.79 Sparviero did almost 300mph. If they stay up at a reasonable altitude, the Royal Navy's carrier based fighters would have a hard time catching them.

 

[Shortround6]

SM.79-III Improved, extended range torpedo bomber introduced during late 1942. It was not available in significant numbers until mid-1943.

From Wiki. The SM.79s came with wide variety engines. The older ones were doing good to hit 270mph. And top speed is not the speed they were flying unless being chased.
On the other had the Fulmar I was at closer to 250mph than the 272mph claimed by the MK IIs so it sort of balances out.