Hybrid aircraft carriers (1 Viewer)

[tomo pauk]

So you launch 20 wheeled a/c at a fleet -- let's be generous here. Maybe six of 'em are fighters? Fourteen strike a/c with lighter loads because launching with minimal headwind (sailing into the wind gives the a/c nothing, sailing with the wind is not going to get you 27 kts over the deck) is problematic, maybe you can get torpedo planes into the air, maybe not. You'd better hope your target isn't fielding a real aircraft carrier.

I'll try and launch 30+ of wheeled aircraft from each hybrid, that is sized like the Andre Doria, or Schanrnhorst, or the Ise/Hyuga; each of these with 2/3rds of the ship devoted to the air component. I'll prefer the dive bombers.

Sailing into the wind gives to the aircraft a lot. Sailing with the wind is trying to shoot oneself in the foot.

Or maybe you launch a floatplane strike.

Nope.

Or maybe you sail these hybrids in the line of battle.

No, again. Big guns are for the case of when the proverbial hits the fan, not of 'let's go plinking'.

 

[Shortround6]

No need to stay with one flight deck, and no need to limit the scenario just to the Med.

If we are discussing the Italians then we are limiting the scenario to the Med. The Italians are not going anywhere else.
If we discuss the Germans then we can discuss the Baltic, the North Sea and the North Atlantic and the Norwegian/Barents seas.

Assuming that somebody does actually build a large Hybrid, what else don't they get, and what does their primary opponent do in response?

 

[tomo pauk]

Assuming that somebody does actually build a large Hybrid, what else don't they get,

At least this:

For the French, Italians, Japanese and Germans, they will have less 'guns firepower' available. They will also make and deploy less of the floatplanes and/or flying boats.

and what does their primary opponent do in response?

A legit question.

 

[EwenS]

Germany was not a signatory.
Expecting that Japanese adhere to the 1930 LNT come late 1930s is illusory. They having no problems leaving the League of Nations already in 1933 shows how much they cared for international treaties.
Italy was also gone from the LoN by 1935, and they were not signatories of the 1937 LNT.

Thus, either of these 3 nations making a big hybrid CV is not a long shot.
We also have a thing of the treaty expiring at the end of 1936.

Germany had no interest in hybrids. She went straight to full carriers with GZ and a planned sister from 1935. Later WW2 plans revolved around full carrier conversions of cruisers or liners.

As for the Japanese, apart from the seaplane carriers already discussed (Tones, Oyodos and Mogami) and which, as I noted, had very specific roles in the Japanese mind, they gave up on the hybrid concept around 1934 with the G6 flying deck cruiser (12,000 tons standard, 3x2 8" guns and 70 fighters) and G8 carrier-cruiser (10,050 tons standard, 1x3 + 1x2 155mm 72 aircraft) designs, until the crisis of mid-1942. Why? Because they were forced to face up to the fact that, with the commissioning of the Ryujo and the Tomozuru incident, they were attempting too much on too little displacement.

So what did they do? Built a proper aircraft carrier based on the G9 design (15,900 tons standard, 73 aircraft with a purely defensive AA armament) that in due course was delivered as Soryu (laid down Nov 1934). Even her construction was delayed by the 4th Fleet Incident of July 1935 that saw the Japanese having to reassess the strength of the warships they had built / were building. That also resulted in some redesign of her close sister, Hiryu, before she was laid down in July 1936. (See Warship 2022 "The IJN Carriers Soryu and Hiryu" and Miroslaw Skwiot "The Japanese Aircraft Carriers Soryu and Hiryu")

The Italians too seemingly never considered hybrids. Having completed a seaplane carrier, Giuseppe Miraglia based on a train ferry hull, in 1923, their thoughts turned to full carriers from 1929, then again in 1933 and again in 1935/36. The last of these projects intended to use the liner Roma. It was the plans for the Roma conversion that were resurrected in 1941, and updated which saw that hull converted to the carrier Aquila that was never completed. (See Warship 2020 "The Quest for an Italian Aircraft Carrier 1922-1929" and Warship 2021 "The Italian Aircraft Carrier Aquila")

The problem for the Italian Navy was Italian law, that while revised in 1931, still left the RA in control of Italian military aviation. It provided for "Auxiliary Aviation" for the RM with little indication of how to implement it. It also limited the tasks assigned to Auxiliary Aviation to shore based and embarked aircraft for maritime recce, "combat" functions such as fleet air defence and strike against enemy vessels were ruled out. It was only in July 1941, after Matapan, that the RA agreed to the urgent initiation of studies for an embarked aircraft with folding wings.

So for those three nations it was an exceedingly long shot for them to develop a hybrid cruiser or battleship carrier.

The USN studied various flight deck cruiser designs in the early 1930s for a flying deck cruiser only to reject them. They were resurrected again in 1939 and rejected again.

Gibbs & Cox the US Naval architects proposed a hybrid battleship for the USSR in the late 1930s and produced a number of designs, none of which were turned into metal.

Britain briefly examined a battleship carrier version of the Lion class battleship in late 1940/ 1941. The DNC considered it "very inferior" to a pure battleship with its unarmourd hangar. The Director of the Gunnery Division made an even better comment:-

"The functions and requirements of carriers and of surface gun platforms are entirely incompatible.....the conception of these designs .....is evidently the result of an unresolved contest between a conscious acceptance of aircraft and a subconscious desire for a 1914 Fleet....these abortions are the results of a psychological maladjustment. The necessary readjustment should result from a proper re-analysis of the whole question, what would be a balanced fleet in 1945, 1950 or 1955?"

A battleship carrier, carrying a complement of defensive fighters, only made sense if available immediately in 1941 given the crisis then being faced in the Eastern Med. Of course it couldn't be, with even a conversion of an existing ship, if one could be found, taking a year or more, and longer if a new ship was laid down. The effort would have been better spent on prioritising completion of the two Implacable class carriers.

If you want to delve deeper into the world of the hybrid warship I'd recommend this title, if you can track down a copy at a reasonable price,

https://www.amazon.co.uk/Hybrid-Warship-Amalgamation-Aircraft-Conways/dp/0851775551/ref=mp_s_a_1_1?crid=32OYNGJE29E1I&dib=eyJ2IjoiMSJ9.jp_jxN6nEfQfC00qTU4DCQ.cpBOexbbEZdM7uwyUkgLhnsU1cIRzs5NAb8F3fR5wmk&dib_tag=se&keywords=the+hybrid+warship&nsdOptOutParam=true&qid=1735320918&sprefix=he+hybrid+warship%2Caps%2C338&sr=8-1

 

[Thumpalumpacus]

I'll try and launch 30+ of wheeled aircraft from each hybrid, that is sized like the Andre Doria, or Schanrnhorst, or the Ise/Hyuga; each of these with 2/3rds of the ship devoted to the air component. I'll prefer the dive bombers.

What benefit do you gain by retaining a rump main battery that can't credibly go up against a surface ship of equal size and at the same time hamstringing one's maneuver by considerations of flight ops? And you'll need to be willing to offer up larger, vulnerable hangars to surface gunfire as well.

Sailing into the wind gives to the aircraft a lot. Sailing with the wind is trying to shoot oneself in the foot.

So you'll need to invent angled decks some fifteen years earlier, or eliminate the superstructure in order to lengthen takeoff runs and ensure safe landings. At that point you may as well build a full-scale carrier, considering the limitations you've placed on both modes of operation.

No, again. Big guns are for the case of when the proverbial hits the fan, not of 'let's go plinking'.

Which happened twice in WWII, on both occasions brought about by extremely poor decision-making. So let's put your thirty-plane hybrid getting caught by the Ugly Sisters. Four 8"-guns at cruiser speed, or the Ise-type at 23 kts with 4x14", I don't see the planes or the guns helping too much.

I think Drachinifel has it right, to paraphrase: if things are so bad you need to make these conversions or half-measures, you probably have bigger problems to worry about anyway, like the weaknesses that put you in that position in the first place.

 

[Shortround6]

So Italy rips the stern turret off the Vittorio Veneto or leaves the two rear turrets off the Duilio? 6 guns and 5 guns respectively.
Trying to yank B turret to add aviation capacity really leaves the ship with not enough guns to fight any other capital ship. Just throw A turret over the side to lighten the ship and run for it

The next question, and rather important one, is what happens to the secondary and/or AA armament? Cut the secondary guns? swap for better AA?

And what do you do with the armor? Lighten the ship up and try for speed or lug thousands of tons of armor around for a gun battle you are hoping doesn't happen?

Basically the idea seems to be lug thousands of tons armor plate and guns (Veneto turret goes 1585metric tons, does not include barbette, etc. )around for a "just in case scenario " in case your destroyers, cruisers screw up.

 

[Thumpalumpacus]

So Italy rips the stern turret off the Vittorio Veneto or leaves the two rear turrets off the Duilio? 6 guns and 5 guns respectively.
Trying to yank B turret to add aviation capacity really leaves the ship with not enough guns to fight any other capital ship. Just throw A turret over the side to lighten the ship and run for it

The next question, and rather important one, is what happens to the secondary and/or AA armament? Cut the secondary guns? swap for better AA?

And what do you do with the armor? Lighten the ship up and try for speed or lug thousands of tons of armor around for a gun battle you are hoping doesn't happen?

Basically the idea seems to be lug thousands of tons armor plate and guns (Veneto turret goes 1585metric tons, does not include barbette, etc. )around for a "just in case scenario " in case your destroyers, cruisers screw up.

Specialization is in some cases much preferable to Swiss-army-knife equipment. This is one of those cases.

 

[EwenS]

Hiya, Ewen. I'm baffled by such a high max speed requirement in view of idea that these were flagships for submarines; it strikes me that they could have dropped this by six or eight knots and picked up spare tonnage for other uses like weapons stowage, fuel, etc.

Do you have any insight as to why this speed requirement was so high?

Firstly the Japanese liked high speeds in their 1930s designs. Soryu & Hiryu & the Shokakus 34+ knots. Their heavy cruisers, even as rebuilt, matched that.

I think though that the answer lies in the comment about "good mobility". The submarines they were designed to support were going to be strung out over some distance. Once a contact report was received from them they might need to move some distance quickly to allow their aircraft to verify it or simply to leave the scene before US destroyers or cruisers caught up with them before they could transmit details of what they found. They carried an extensive comms suite to ensure that they could fulfill the task of reporting back to the main fleet. The radio eqpt in a low sitting sub would not have the same range. (In the late1920s /1930s RN patrol subs in the Far East had tall, collapsible radio aerials to ensure their reports could be received at their bases in Hong Kong & Singapore).

More surprising than the outright speed is the radius of action at a relatively high 18 knots. 10,000+ nm. It was greater than most other ships the IJN had. Only the Tone class (9,000 @ 18 knots) & Shokaku class (9,700 @ 18 knots) seem to get close.

The closely related (at least in terms of time) Agano class were intended as flagships for the destroyer flotillas were 35 knots, necessary to keep up with their charges, but were lighter, with a radius of action of 6,300 miles at 18 knots.

Most US cruisers of the period were designed to cruise efficiently at 15 knots to produce similar range figures to Oyodo.

More weapons would have meant a larger hull, requiring bigger heavier machinery for thecsame speed etc etc etc.

 

[ThomasP]

As I mentioned upthread and as mentioned by Thumpalumpacus:

So you'll need to invent angled decks some fifteen years earlier

I am not sure if a 10° angled deck would be enough, but 15° should do, and when using arrestor gear it takes less length of deck to land than it does to take off - particularly if you use a catapult.

400 ft of flight deck for take-off and landing runs should be enough for relatively low TO and landing speeds. You would not be able to launch any of the heavier aircraft without a catapult, but scout-planes, early-war fighters (A6M, Hurricane, etc) and dive bombers (SBC-4, Val?) should be doable.

And an odd and little appreciated aspect of the angled flight deck is that if the leading edge is ~1/2 of the length behind the bow there is less chance of pounding or damage to the flight deck due to heavy seas than with a conventional carrier.

 

[z42]

I'm glad that we are not in the "this ship is better than this ship" mode from now on.

No need to stay with one flight deck, and no need to limit the scenario just to the Med.

If we accept the idea that the fight will be between groups of ships rather than 1-vs-1, then we can abandon the idea of the all-singing all-dancing hybrid carrier, no? The gunships can close to gun range with a 'full' complement of guns, and without having to risk the hangar with the expensive planes turning into a flaming inferno once the shooting starts. And the carriers can stand back from the gun action well out of range of enemy guns, and concentrate on air operations, without having to dedicate displacement to heavy guns which are useless in that role.

For the Italians in particular, where do they get the carriers from, and what do they give up in order to get them? Seems the favorite alternative history option for the Italians is to convert the Francesco Caracciolas. But that brings into light the state of the Italian economy post-WWI. The FC hull was launched, but then languished for a number of years due to lack of funding to complete it, before ultimately being scrapped. The Aguila could have been a perfectly Ok first carrier, but of course it wasn't finished before the war was over for Italy. Starting an Aguila-like conversion project earlier might have been an option, but before the war it might not be feasible to just commandeer an in-use ocean liner into the yard for conversion? Maybe convert one or two of the Cavours or Dorias as part of their modernization?

And how to equip the carriers? Add a tailhook to the CR.42 might have made a decent enough carrier fighter for the beginning of the war? Yes, it's a biplane, but fast enough to catch Swordfishes and Albacores, and probably better than the Gladiator as a fighter. What about recon, dive bomber, and torpedo bomber? Maybe save a buck by forgetting about the torpedo bomber and do a combined scout/dive bomber plane?

 

[Warspite63]

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

Agree .... to a point They were really carriers built to the treaty limits - which allowed the 8" armament on a carrier. Akagi and Kaga mounted 10 x 7.9" when initially converted at the same time

 

[Shortround6]

favorite alternative history option for the Italians is to convert the Francesco Caracciolas.

Scrap them and start over, unless you can get the treaty guys to really give you a good deal. Like not count them as tonnage
The Caracciola was about 12.5% completed hull wise and about 5% machinery. They were designed in 1913-14 and the Caracciola was laid down Oct 1914. They were designed for oil firing but that was as modern as the machinery got. The others were barely started. By even 1920-24 they would need substantial upgrading. Boilers were making very large advances.
Check to see if the Caracciola had ungeared turbines or geared Turbines. The Andrea Doria went from 20 boilers to 8 and went from 30,000hp to 75,000hp, Also went from 4 shafts to 2 shafts. Huge changes to machinery spaces, compartmentation and auxiliary system.
If kept and used the Machinery would defiantly need to be replaced in the late 30s and what else doesn't get rebuilt or modern ships built?

 

[z42]

Scrap them and start over, unless you can get the treaty guys to really give you a good deal. Like not count them as tonnage

They could sneak in under the same treaty clauses as the Lexingtons, Akagi&Kaga, namely a limit of 33000 tons for a conversion vs. 27000 tons for a from-scratch bespoke carrier build.

The Caracciola was about 12.5% completed hull wise and about 5% machinery. They were designed in 1913-14 and the Caracciola was laid down Oct 1914. They were designed for oil firing but that was as modern as the machinery got. The others were barely started. By even 1920-24 they would need substantial upgrading. Boilers were making very large advances.
Check to see if the Caracciola had ungeared turbines or geared Turbines. The Andrea Doria went from 20 boilers to 8 and went from 30,000hp to 75,000hp, Also went from 4 shafts to 2 shafts. Huge changes to machinery spaces, compartmentation and auxiliary system.
If kept and used the Machinery would defiantly need to be replaced in the late 30s and what else doesn't get rebuilt or modern ships built?

Indeed. The FC's might have been interesting had the Italians had the will and budget to build up a naval aviation capability starting immediately after WWI. But if starting in the 1930'ies, there's surely more attractive options, and by then the FC hull has long since been scrapped anyway.

 

[Warspite63]

As I mentioned upthread and as mentioned by Thumpalumpacus:


I am not sure if a 10° angled deck would be enough, but 15° should do, and when using arrestor gear it takes less length of deck to land than it does to take off - particularly if you use a catapult.

400 ft of flight deck for take-off and landing runs should be enough for relatively low TO and landing speeds. You would not be able to launch any of the heavier aircraft without a catapult, but scout-planes, early-war fighters (A6M, Hurricane, etc) and dive bombers (SBC-4, Val?) should be doable.

And an odd and little appreciated aspect of the angled flight deck is that if the leading edge is ~1/2 of the length behind the bow there is less chance of pounding or damage to the flight deck due to heavy seas than with a conventional carrier.

Interestingly, the USN was already heading in that direction: https://laststandonzombieisland.com...ck-cruiser-hybrid-carrier-from-warship-13.jpg

 

[EwenS]

Nope. The point of the angled deck was to separate take off and landing runs onto different paths.

The USN flight deck cruiser simply set the straight deck, with landing area and take off area on the same axis, a few degrees (3 IIRC) to port so it was not narrowed abreast the island superstructure. The latter was needed to support the directors for the main armament. Look at the location and angle of the arrester gear aligned with the deck axis and not at an angle.

 

[Thumpalumpacus]

Firstly the Japanese liked high speeds in their 1930s designs. Soryu & Hiryu & the Shokakus 34+ knots. Their heavy cruisers, even as rebuilt, matched that.

I think though that the answer lies in the comment about "good mobility". The submarines they were designed to support were going to be strung out over some distance. Once a contact report was received from them they might need to move some distance quickly to allow their aircraft to verify it or simply to leave the scene before US destroyers or cruisers caught up with them before they could transmit details of what they found. They carried an extensive comms suite to ensure that they could fulfill the task of reporting back to the main fleet. The radio eqpt in a low sitting sub would not have the same range. (In the late1920s /1930s RN patrol subs in the Far East had tall, collapsible radio aerials to ensure their reports could be received at their bases in Hong Kong & Singapore).

More surprising than the outright speed is the radius of action at a relatively high 18 knots. 10,000+ nm. It was greater than most other ships the IJN had. Only the Tone class (9,000 @ 18 knots) & Shokaku class (9,700 @ 18 knots) seem to get close.

The closely related (at least in terms of time) Agano class were intended as flagships for the destroyer flotillas were 35 knots, necessary to keep up with their charges, but were lighter, with a radius of action of 6,300 miles at 18 knots.

Most US cruisers of the period were designed to cruise efficiently at 15 knots to produce similar range figures to Oyodo.

More weapons would have meant a larger hull, requiring bigger heavier machinery for thecsame speed etc etc etc.

Thanks for the detailed answer, much appreciated.

 

[Warspite63]

Interesting conversation, folks! I've pondered the whole hybrid question periodically. It's hard for me not to think of it as a cool-looking concept in search of a viable mission/role. About the ONLY one I can come up with is as an anti-raider convoy escort, which would point at the RN (at least in the early part of the war). Cruiser guns would be a risk for any Hilfskreuzer and could not be ignored by a Panzerschiff; while the air complement would greatly expand the scouting capabilities, and the ability to lob a torpedo at a raider would further elevate the risk factor. Per Friedman, in the late 30's, there was an RN design with 3 triple 6" turrets forward and one aft, with an aircraft handling deck aft - basically, an enlarged Gotland. Even this, to me, is more a standard cruiser with enhanced aviation facilities, vs. a true hybrid. There is no cpccity to land on aircraft, which means floatplanes

LaCroix and Wells' Japanese cruiser bible has a description of a submarine-supporting light flightdeck cruiser, with 2 triple 6" turrets forward. Thss was a true hybrid, basically being a light carrier with 2 cruiser turrets

Nope. The point of the angled deck was to separate take off and landing runs onto different paths.

The USN flight deck cruiser simply set the straight deck, with landing area and take off area on the same axis, a few degrees (3 IIRC) to port so it was not narrowed abreast the island superstructure. The latter was needed to support the directors for the main armament. Look at the location and angle of the arrester gear aligned with the deck axis and not at an angle.

That is the rationale for an angled flight deck NOW .... as you mentioned, on the design I posted, it was a way to preserve flight deck width abreast the island. It is, nevertheless, an angled flightdeck. Somewhere, I read an article that such ships, if built, would most likely have been converted to light carriers in WW2. In that case, they quite possibly would have lead to the evolution of the 'separate landing and take-off areas'. In truth, there are other ways to preserve flightdeck width: either sponson out the island, or off set the entire flightdeck (like Joffre (one of who's design iterations had a quad 12" turret aft...). Instead, the US N angled the forward end of the flightdeck

 

[tomo pauk]

For the Italians in particular, where do they get the carriers from, and what do they give up in order to get them? Seems the favorite alternative history option for the Italians is to convert the Francesco Caracciolas. But that brings into light the state of the Italian economy post-WWI. The FC hull was launched, but then languished for a number of years due to lack of funding to complete it, before ultimately being scrapped. The Aguila could have been a perfectly Ok first carrier, but of course it wasn't finished before the war was over for Italy. Starting an Aguila-like conversion project earlier might have been an option, but before the war it might not be feasible to just commandeer an in-use ocean liner into the yard for conversion? Maybe convert one or two of the Cavours or Dorias as part of their modernization?

Italians have had 4 BBs left over from ww1 that were good enough to be retained. Perhaps they go with the 1st two conversions as-is (since they were lagging late with the Littorios or the like), and have two of the others (Andrea Doria, Diulio) modified into the hybrids.
Germans can design the S&G as the hybrids from day one.

And how to equip the carriers? Add a tailhook to the CR.42 might have made a decent enough carrier fighter for the beginning of the war? Yes, it's a biplane, but fast enough to catch Swordfishes and Albacores, and probably better than the Gladiator as a fighter. What about recon, dive bomber, and torpedo bomber? Maybe save a buck by forgetting about the torpedo bomber and do a combined scout/dive bomber plane?

Tailhook on the CR.42 would've certainly allowed them to start with training, and will net them an useful fighter.
Next step as a fighter - I'd prefer the Reggianne stuff. They were dabbling in the navalized fighters anyway. Recon can be done with something like the two seater spin off (like the Re.2003 was), while the main attack aircraft can be a dive bomber (a bombed-up Re.2000/2002/2003).
Ideally, a fighter like Re.2001 should've been the main fighter-attacker for 1941-42, but the low output of the DB 601s from A-R will still be an issue.

I'm also not sold on the torpedo bombers for this case.