Optimize the Axis Navies for WW2

[CaptainCalvert]

For me, something like a merchant carrier would be better than a full carrier. If only because they have experience with Armed Merchant Cruisers, so they already have some background for understanding conversion process and crewing needs. We're then looking mainly at scouting and limited attack capacity for the aircraft which the float planes will be suitable for. The development needed is then how best to recover aircraft, while the outline attack plans could potentially be worked through with Japan - provided they can offer something that the Japanese want [1].
The other thing is that building or trialling an actual carrier is going to get the RN interested. I'll believe it's possible to prepare for a merchant carrier conversion on the quiet, but I can't see how it would be possible to hide constructionand then trials of an actual carrier.

[1] fuel - Germany doesn't have much to spare, technology - maybe aircraft cannon, 37mm AA, and tank designs? But then does Japan want to admit to a lack of capability and if so, do they have the industrial capacity to build them. Plus the Panzer 1 and 2 might be quite good in the mid 1930s when naval trials would be underway but less so by 1940. And there's still the question of industrial capacity

 

[Naval Aviation Fan]

[1] fuel - Germany doesn't have much to spare, technology - maybe aircraft cannon, 37mm AA, and tank designs? But then does Japan want to admit to a lack of capability and if so, do they have the industrial capacity to build them. Plus the Panzer 1 and 2 might be quite good in the mid 1930s when naval trials would be underway but less so by 1940. And there's still the question of industrial capacity

Germany can build tankers, which the Japanese have to few of, and the German are not constrained on constructing, and then swap tankers for training on IJN carriers. This means the Japanese carriers get more training time wear and tear, the Germans get the benefit of this training, and the Japanese economy gain a big help without the need to alter their own naval buildup.

 

[Gudestein]

I think this thread is starting to develop a German ATL carrier doctrine.Excellent.
Carrier GS sizes, Panzer schiffe, and I would add one or two Spahkreuzer. If you have two of these groups in the Atlantic, the convoys would need ridiculous level of protection and the scouting ability would really improve detection of ships sailing alone.
Most important is that the carriers allows these task forces to avoid being hunted down because the can find superior forces before it’s too late.
A few dittmarschen class or other tankers would amplify efficacy quite substantially.

 

[NOMISYRRUC]

Link to Post 45 which this Post replaces.

1919 to c. 1932 - Build to the limits allowed by the Treaty of Versailles.​

The exercise has two objects.

1. The Kriegsmarine inherits a larger number of modern warships from the Reichsmarine and in the case of Light Cruisers it inherits 8 half-decent ships instead of one obsolete ship and 5 bad ships.
2. The Kriegsmarine inherits a larger naval armaments industry from the Reichsmarine so that more of the ships that it's allowed to have under the Anglo-German Naval Agreement can be completed.

This means that the Weimar Republic has to spend more money. However, I believe that in spite of Germany's economic problems the extra expenditure won't break the Reichsbank.

Armoured Ships.

• Lay down 6 Deutschland class 1928-32 (for completion 1933-36) ITTL instead of the 3 that were laid down 1928-32 (and completed 1933-36) IOTL.
• According to Jane's 1931 they were going to cost £4 million each, which if correct (and I think it is) involves the expenditure of £12 million over 9 years (1928-36) to build the 3 extra ships and in spite of Germany's economic problems that won't break the Reichsbank.
• A British County class Heavy Cruiser cost £2.4 million each (according to a Cabinet Paper written in October 1937) and that's 60% of the estimated cost of a German Armoured Ship. Given that a Deutschland displaced about 20% more than a County, had a heavier armament than a County and that (on a cost per ton basis) British warships were probably cheaper to build than German warships. Therefore, I think it's plausible that a Deutschland would have cost about 65% more to build than a County class Heavy Cruiser.
• IOTL Armoured Ships D and E (i.e. Nos. 4 and 5 of the 8 Armoured Ships that the Treaty of Versailles allowed Germany to have) were laid down on 25.01.34. However, both ships were suspended on 05.07.34 (when Hitler gave his consent a third turret) and eventually re-laid down at the same shipyards on 15.06.35 & 06.05.35 respectively. These ships were the Scharnhorst and Gneisenau.
• ITTL Armoured Ships G and H (i.e. Nos. 7 and 8 of the 8 Armoured Ships that the Treaty of Versailles allowed Germany to have) were laid down on 14.02.34. However, both ships were suspended on 05.07.34 (when Hitler gave his consent a third turret) and eventually re-laid down at the same shipyards on 15.06.35 & 06.05.35 respectively. These ships were the Scharnhorst and Gneisenau.
• @NoMommsen, I'm laying 6 down Deutschalnd class 1929-1932 instead of the 8 Armoured Ships that the Treaty of Versailles allowed Germany to have because 8 would "mucks things up". See below:
  • Germany was allowed 183,750 tons of capital ships under the Anglo-German Naval Agreement of 13.06.35. That is 35% of the 525,000 tons of Capital Ships that the British Empire was allowed under the Washington Naval Treaty.
  • 183,750 tons minus the 132,000 tons for the 8 Deutschland class (10,000 tons each) and 2 Gneisenau class (26,000 tons each).
  • Equals 51,750 tons of unused tonnage, which, isn't enough to build Bismarck and Tirpitz, because their official standard displacements were 35,000 tons.
  • However, if 6 Deutschlands and 2 Gneisenaus had been built there would have been 71,750 tons of unused tonnage, which is enough to build Bismarck and Tirpitz.

Cruisers.

• The tonnages in this section are the standard displacements according to Conway's 1922-46.
• Instead of the 6 ships laid down 1921-33 IOTL lay down all 8 ships allowed by the Treaty of Versailles 1926-33 at the rate of one per year.
• The 8 ships were enlarged versions of the OTL Leipzig and Nürnberg with standard displacements is the region 7,200 to 7,500 tons instead of the 6,515 to 6,980 tons that the Königsberg to Nürnberg classes displaced IOTL. (6,650 tons Königsberg class, 6,515 tons Leipzig & 6,980 tons Nürnberg.)
• This made them roughly the same size as the contemporary British Leander & Amphion classes of Light Cruisers (6,830 to 7,270 tons) and French La Galissonnière class Light Cruisers (7,600 tons).
• The increase in displacement allowed the ships to be built with stronger hulls and as a result they avoided the structural defects that ruined the OTL Königsberg to Nürnberg classes. As a result the Kriegsmarine would have had 8 satisfactory Light Cruisers in September 1939 instead of none.
• However, as the OTL Leipzig wasn't laid down until 1928 it might not be possible to fit her Combined Steam and Diesel (COSAD) machinery to the ships laid down in 1926 and 1927. If that's the case the those ships will have to have the Combined Steam on Diesel (COSOD) machinery used by the OTL Königsberg class.
• ITTL there was a gap of 5 years between the laying down of Leipzig (1928) and Nürnberg (1933). According to Whitley in "German Cruisers of World War Two" this gap was because the Reichsmarine's leaders didn't know what type of Light Cruiser they wanted rather than not being able to obtain the money to build more cruisers. Eventually, they decided that Cruiser F (Nürnberg) was to be a much enlarged version of Cruiser E (Leipzig) displacing 8,000 tons. However, it wasn't possible to design such a ship by the time they had made their minds up because the Cruiser design team was working on what became the Hipper class and had no spare capacity. Therefore, Nürnberg had to be a virtual repeat of Leipzig. Which, is a long winded way of saying that I think Germany could afford to lay down four 7,200 to 7,500 ton Light Cruisers at the rate of one per year 1929-32.

Destroyers - Version 1.

• IOTL and TTL the Reichsmarine had 32 Destroyers in 1922 with an average displacement of 608 tons. They were completed 1907-13 and therefore under the terms of the Treaty became overage between 1922 and 1928.
• However, the Treaty of Versailles only allowed Germany to build 16 Destroyers of 800 tons and 16 Torpedo Boats of 200 tons to replace them.
• IOTL 12 small destroyers of the Torpedo Boat Type 1923 & 1924 were laid down 1925-27 out of the 16 that were allowed.
• ITTL the Weimar Republic built the full allowance of 16 Destroyers at the rate of 2 per year 1925-32. In common with OTL they were built to the Torpedo Boat Type 1923 & 1924 designs.
• IOTL the allowance for 16 Torpedo Boats of 200 tons wasn't used.
• ITTL the Weimar Republic built the full allowance of 16 Torpedo Boats and laid them down at the rate of 2 per year 1925-32. They wouldn't be large enough to be effective warships (despite displacing somewhat more that the official 200 tons) but they would help Germany maintain a larger naval armaments industry 1919-33 and as already written maintaining a larger naval armaments industry is one of the objectives of the excercise.

Destroyers - Version 2.

• IOTL and TTL the Reichsmarine had 32 Destroyers in 1922 with an average displacement of 608 tons. They were completed 1907-13 and therefore under the terms of the Treaty became overage between 1922 and 1928.
• In Version 2 of TTL the Treaty of Versailles wasn't as strict and allowed Germany to have 32 Destroyers of 800 tons and no Torpedo Boats of 200 tons to replace them.
• Therefore, the Weimar Republic built the full allowance of 32 Destroyers at the rate of 4 per year 1925-32. In common with OTL they were built to the Torpedo Boat Type 1923 & 1924 designs.

Summary

• IOTL Germany laid down the Light Cruiser Emden in 1921 and 3 Armoured Ships, 5 Light Cruisers & 12 Small Destroyers in the period 1925-33 of which Emden was obsolete by 1939 and the other 5 Light Cruisers had weak hulls that severely limited their usefulness.
• In Version 1 of TTL Germany laid down 6 Armoured Ships, 8 Light Cruisers, 16 Small Destroyers and 16 (Very) Small Torpedo Boats in the period 1925-33.
• In Version 2 of TTL Germany laid down 6 Armoured Ships, 8 Light Cruisers and 32 Small Destroyers in the period 1925-33.
• In both versions of TTL that's an average of one Armoured Ship a year 1928-33, one Light Cruiser a year 1926-33 and 4 Surface Torpedo Craft 1925-32.
• Apart from the Light Cruisers being half-decent warships ITTL there were no improvements in the quality of the ships built ITTL.

 

[Capt Thunderbolt]

I always thought the idea of a BF109 as a carrier fighter a bit suspect.

Given the problems of the Spitfire getting its sea legs and my understanding is that the 109s undercarriage was worse.

The He112B would be an option. Wider track under cart, and throw in folding wings it could be very good for carriers.

Another positive, it's not BF109 and make less waves from a LW view

 

[Dorknought]

The problem is if they are to cooperate, to what end?

While the thing that could draw them together is that they were shafted by the Western powers, they need to figure out who to coordinate against as they clearly can't take everyone all at once.

We can assume that the German/Italian/Japanese navies would have the advantage by picking the time they will strike. Their problem is that they can't concentrate their forces but they can cooperate against a single foe.

• Germany wants to emasculate France and drop it a peg in Western Europe.
• Italy wants to be dominant in the Med
• Japan wants to exclude western powers from mainland China.

They have 2 main foes:

• Soviet Russia
• Anglo-sphere as a subset of 'liberal democracies' of which only France really matters

Pick one to knock off first.

• Removing Russia gets Italy nothing
• There is a need to keep the Anglosphere divided

Russia: Germany controls the Baltic, Italy blocks the Eastern Med and Japan controls access through the east. This has to be an 'anti-comintern' war to keep the West from intervening. Japan would probably have to lead to draw down Soviet forces away from Europe. Limited objectives would be Finland and Baltic states in German sphere, and Japanese possession of the Maritime provinces. Italy gains nothing. This is more a land based war with navies playing a secondary part.

GB: Again, Japan would have to pull the RN to the Pacific before Germany and Italy declare their hand. In this case Germany would be better off shifting the fleet to the Med before the war to aid the Italians. Britain can't invade Germany but Germany can contribute to cutting off the Empire's windpipe and perhaps keeping France neutral.

US: None of the three can really threaten the US.

So what is each navy good at?

• Italy - light and special forces
• Germany - anti-commerce warfare
• Japan - Land based Naval airforces and naval landings

Japan and Italy represent 4.75 (3+1.75) vs 5 for the RN. Germany could have a nominal 128,000 tons of cruisers giving an advantage of 440,000tons vs 320,000 tons RN. If the focus is on putting pressure on all points of the Empire then Germany can build a cruiser fleet of 8 10k ton 9x8" CA (32knots) and 8 5-6k ton 6x6" (32kts) Spähkreuzer and base these out of Italian East Africa together with IJN units that rotate through the same bases. The Italians and Japanese can provide submarines, the IJN a CVL and the Germans the heavy escort for task groups to effectively shut down Indian Ocean trade if war breaks out. The Italians will need to stay as strong as possible in the Med but using IJN style landing forces and dedicated Naval Airforce Units to take Malta and neutralise Alexandria and Gibraltar.

In the North Sea, the Germans with Italian support can rely on light forces. If Germany can have it's cruiser force of 128,000 tons by 1930 then it can make a case for parity with Italy and France paving the way for 5 35,000 battleships (or 10 17,500 ton cruisers), 60,000 tons of carriers and about 50,000 tons of destroyers to be built in the early - mid 1930's. Perhaps a concession can be made to not build submarines. If you can co-opt Spain and The Netherlands then you have additional bases, much greater pressure on the British Empire and sources of oil.

 

[NOMISYRRUC]

Part of Post 124.

Armoured Ships.

• @NoMommsen, I'm laying 6 down Deutschalnd class 1929-1932 instead of the 8 Armoured Ships that the Treaty of Versailles allowed Germany to have because 8 would "mucks things up". See below:
  • Germany was allowed 183,750 tons of capital ships under the Anglo-German Naval Agreement of 13.06.35. That is 35% of the 525,000 tons of Capital Ships that the British Empire was allowed under the Washington Naval Treaty.
  • 183,750 tons minus the 132,000 tons for the 8 Deutschland class (10,000 tons each) and 2 Gneisenau class (26,000 tons each).
  • Equals 51,750 tons of unused tonnage, which, isn't enough to build Bismarck and Tirpitz, because their official standard displacements were 35,000 tons.
  • However, if 6 Deutschlands and 2 Gneisenaus had been built there would have been 71,750 tons of unused tonnage, which is enough to build Bismarck and Tirpitz.

Alternatively.

• If the Germans did build 8 Deutschlands and 2 Gneisenaus they could have used the 51,750 tons to turn "The Twins" into "The Quadruplets" by building a second pair of Gneisenaus instead of Bismarck and Tirpitz.
• IOTL Gneisenau & Scharnhorst were built in an average of 40 months while Bismarck & Tirpitz were built in an average of 51 months.
• Therefore, if a second pair of Gneisenau class had been laid down in 1936 instead of Bismarck & Tirpitz it's plausible that they'd have been completed around the end of 1939 and operational in time to take part in Operation Juno.
• As "a bird in the hand is worth two in a bush" a Capital Ship force of 4 Battle Cruisers and 8 Armoured Ships plus no Battleships nearing completion in the Summer of 1940 (not allowing for losses) would have been much better for the Kriegsmarine than the OTL Capital Ship force of 2 Battle cruisers and 3 Armoured Ships plus 2 Battleships nearing completion in the Summer of 1940 (not allowing for losses).

 

[NOMISYRRUC]

Some background information.

The Original A.G.N.A. Tonnage Quotas

At October 1935 The Germans Planned To Use Their Capital Ship Quota to Build

The Agreement allowed them to transfer unused tonnage from other categories to this category which is why they planned to build three 35,000 ton Battleships.
At October 1935 it was planned that Bismarck & Tirpitz would take 39 months to build and be completed in October 1939 & February 1940 respectively.
In the event they took an average of 51 months to build and were completed in August 1940 & February 1941 respectively.
At October 1935 Battleship H was to have been laid down in October 1937 and completed in February 1941.
However, she wasn't laid down until 1939 due to a shortage of suitable slipways and it being re-designed as a "H" class battleship.
A fourth 35,000 ton ship (Battleship J) was added in January 1937 after the British announced Duke of York, Anson and Howe.
Battleship J ship was to have been laid down in May 1938 and completed in November 1941.
However, it wasn't laid down until 1939 due to a shortage of suitable slipways and it being re-designed as a "H" class battleship.

The Germans Used Their Cruiser Quota to Build

Seydlitz and Lützow weren't completed.
33,250 tons weren't used.
According to Whitley in "German Cruisers of World War Two" this was due to the time it took to decide the characteristics of what became the 7,800 ton Cruiser M class.
According to him 4 were ordered in May 1938 and cancelled before they were laid down.
The entry on the Cruiser M class on www.german-navy.de says the same.
Conway's 1922-46 says 3 were laid down in 1939.​

 

[Gudestein]

Part of Post 124.

Alternatively.

• If the Germans did build 8 Deutschlands and 2 Gneisenaus they could have used the 51,750 tons to turn "The Twins" into "The Quadruplets" by building a second pair of Gneisenaus instead of Bismarck and Tirpitz.
• IOTL Gneisenau & Scharnhorst were built in an average of 40 months while Bismarck & Tirpitz were built in an average of 51 months.
• Therefore, if a second pair of Gneisenau class had been laid down in 1936 instead of Bismarck & Tirpitz it's plausible that they'd have been completed around the end of 1939 and operational in time to take part in Operation Juno.
• As "a bird in the hand is worth two in a bush" a Capital Ship force of 4 Battle Cruisers and 8 Armoured Ships plus no Battleships nearing completion in the Summer of 1940 (not allowing for losses) would have been much better for the Kriegsmarine than the OTL Capital Ship force of 2 Battle cruisers and 3 Armoured Ships plus 2 Battleships nearing completion in the Summer of 1940 (not allowing for losses).

Excellent posts. One thing though is that the Germans would need to lie the Deutschland class as 10000 tons so they could build 8 and the possible 4T& B or 3S&Gs plus two B&T if AGN is per OTL.

 

[Gudestein]

Part of Post 124.

Alternatively.

• If the Germans did build 8 Deutschlands and 2 Gneisenaus they could have used the 51,750 tons to turn "The Twins" into "The Quadruplets" by building a second pair of Gneisenaus instead of Bismarck and Tirpitz.
• IOTL Gneisenau & Scharnhorst were built in an average of 40 months while Bismarck & Tirpitz were built in an average of 51 months.
• Therefore, if a second pair of Gneisenau class had been laid down in 1936 instead of Bismarck & Tirpitz it's plausible that they'd have been completed around the end of 1939 and operational in time to take part in Operation Juno.
• As "a bird in the hand is worth two in a bush" a Capital Ship force of 4 Battle Cruisers and 8 Armoured Ships plus no Battleships nearing completion in the Summer of 1940 (not allowing for losses) would have been much better for the Kriegsmarine than the OTL Capital Ship force of 2 Battle cruisers and 3 Armoured Ships plus 2 Battleships nearing completion in the Summer of 1940 (not allowing for losses).

Excellent posts. One thing though is that the Germans would need to lie the Deutschland class as 10000 tons so they could build 8 and the possible 4T& B or 3S&Gs plus two B&T if AGN is per OTL.
Add the 15 inch from the start on the S&G and it’s a superior fleet to the British fast ships

 

[Astrodragon]

A couple of slightly inconvenient points while the Germans are building light carriers and the RN are into the lead-laced pink gins.
The RN converted shios had a massive design advantage, they kne what a carrier needed and so how to design one that works. Germany doesnt.
Second, there is a LOT of specialised kit you need for the adapted carrier - the RN build program was limited by not having it. The Germans wont have this either (they may not even know wht they need!) and they probably dont know how to build it either.

 

[NOMISYRRUC]

Excellent posts. One thing though is that the Germans would need to lie the Deutschland class as 10,000 tons so they could build 8 and the possible 4T& B or 3S&Gs plus two B&T if AGN is per OTL.

They were lying in the first place.
This is the table that I uploaded into Post 128 and is what they did IOTL.

.

This is the Alternative Proposed in Post 127
That is 8 Deutschlands and 4 Gneisenaus.

Add the 15 inch from the start on the S&G and it’s a superior fleet to the British fast ships.

I agree, but it might be easier said than done.

Although I didn't make it explicit in Post 127 "The Quadruplets" of that timeline were completed with nine 11" guns in three triple turrets like "The Twins" of OTL and for the same reason, that is to get them into service as quickly as possible. In that timeline sixteen triple 11" turrets would have been built for the eight Armoured Ships built in Post 127 instead of the six built for the three Armoured Ships built IOTL. That's mass production by interwar capital ship gun-turret standards and I think that Germany's naval arms industry would be able to produce another twelve for "The Quadruplets" of TTL faster than the six that were built for "The Twins" IOTL. Re-tooling to build twelve 15" turrets would delay their completion even if the design was ready and waiting to be put into production. Time was not on the Kriegsmarine's side so it needed as many adequate ships as quickly as possible as soon as possible rather than ordering better ships that would have taken longer to build.

 

[Naval Aviation Fan]

Excellent posts. One thing though is that the Germans would need to lie the Deutschland class as 10000 tons so they could build 8 and the possible 4T& B or 3S&Gs plus two B&T if AGN is per OTL.
Add the 15 inch from the start on the S&G and it’s a superior fleet to the British fast ships

Now you're talking.

 

[Naval Aviation Fan]

A couple of slightly inconvenient points while the Germans are building light carriers and the RN are into the lead-laced pink gins.
The RN converted shios had a massive design advantage, they knew what a carrier needed and so how to design one that works. Germany doesn't.
Second, there is a LOT of specialised kit you need for the adapted carrier - the RN build program was limited by not having it. The Germans won't have this either (they may not even know what they need!) and they probably don't know how to build it either.

One point on this post. If you are speaking in terms of OTL, I would wholeheartedly agree with your points, but the purpose in this ATL is to optimize all three Axis navies, and specifically by working together, so with the POD being a ticked off Japan wanting to help Germany distract the European powers from the Far east, what does Japan have that the Germans don't in 1923-1933.

Japan has no restrictions on her ability to design, build, and test aircraft, submarines, and big naval guns, to name but three. If the Japanese want to hard press the RN?MN with local matters, then the strongest opposition would be a stronger German navy, Italy is to weak to do this on their own, but Germany and Italy together can tie up allied navies very nicely.

Japan invites Germany to invest in the three items above (among many others), and additionally allows the Germans to timeshare on the IJN carriers in 1923-1933, so that by the time the Germans are going to lay down their first carriers (in 1929) they will already have a pretty good idea how to build, maintain, use and man early carriers, so we won't be seeing anything like the Graf Zeppelin class being built, and what they do build will have aircraft that have their origin back in prototypes built in Japan, and tested there, alongside Japanese carrier type aircraft purchased, license built initial aircraft, so no Bf-109T here either, as the naval fighters and bombers are going to predate Luftwaffe aircraft by some years.

Another thing I would like to see folks discuss:
Germany really needs to have some design studies for a commerce raider carrier, and what such a ship would need, from range and replacement aircraft being able to be either shipped/flown out, or built and/or purchased in South America or other locations outside Germany itself. For instance, Italy as a Neutral in the first 9 months of the war, could they ship replacement aircraft (in crates, as cargo) to south american nations, ostensibly for their own use, but somehow being purchased by Germany, once they are assembled and test flown? If so, this would be a great help for extending the effectiveness of the deployed carriers. As with all commerce raiders, eventually they will be run to ground, but how much damage can the Germans do with them before then, and what if they could, once they get cornered, just legit sell them to Argentina, rather than let them just be sunk/scuttled.

But in addition to commerce raider carriers, what about a "Breakout Support Carrier", that is meant to support German surface raiders in running the G-I-UK gap, and then returning home?

I could see two types:
1) Big, fast, long range, heavily armored and minutely subdivided for survivability. Probably more of a target for enemy air attacks than an all out operational carrier in it's own right, so more toughness in resisting damage that a big airwing.

2) Small, cheap, converted merchant shipping, that maximized airgroup over all other factors (not including ability to sail in any weather, this ship type will be mainly for use in the North Sea, after all), with the idea that these ships, being cheap and disposable can serve as shuttles for the big carrier replenishment needs.

 

[Astrodragon]

Given that the German economy was maxed out during this period, where are the considerable resources coming from?
Also, while all this construction and development are going on, for how long does the RN drink the lead paint?

 

[Cryhavoc101]

The He112B would be an option. Wider track under cart, and throw in folding wings it could be very good for carriers.

Another positive, it's not BF109 and make less waves from a LW view

Didn't both the He112 and 'later' He100 (didn't want to call it an He113 being a superstitions lot) have higher landing speeds than the 109?

Otherwise yes

 

[NoMommsen]

I wonder ... how easily many here accept the Reichsmarine leaders attutude about the 200 t class.

Given the 'modern times' examples of german Jaguar and Tiger classes, sowjet Osa and Matka classes and swedisch Spica and Norköping classes I would render some fighting vessel in this class even in the early 1930 as a bonus with their even compared to the later Kriegsmarine S-boats increased fire power and seaworthyness.
Without a doubt they would rather end with 1930s engine tech in the 35kn plus class instead nearing 40 kn but this might improve as it did IOTL with the S-boats.
The missile canisters of modern times could here IMHO easily be replaced by torpedo tubes and replacement torps and - esp if looking at Matka class - the artilleristic equipment of the early thierties would still be less heavy than the turrets of modern times.

I couls also see some 'modern' (aka early thierties) version of a 250 t class boat with modern - lighter and more powerfull - machinery.

The 'overweight' of perhaps a dozen or a couple of dozen tons ... probably something somewhat disguisable or ... silently acceptable to entente bypassers from 1927 (end of Inter Allied Commision of (armaments]vControl) onwards.

 

[Cryhavoc101]

A couple of slightly inconvenient points while the Germans are building light carriers and the RN are into the lead-laced pink gins.
The RN converted shios had a massive design advantage, they kne what a carrier needed and so how to design one that works. Germany doesnt.
Second, there is a LOT of specialised kit you need for the adapted carrier - the RN build program was limited by not having it. The Germans wont have this either (they may not even know wht they need!) and they probably dont know how to build it either.

I am full aware that for the most part 'improving the KM' is little better than rearranging deck chairs on the Titanic

No AGNA like agreement as OTL that constrained the German Navy absolutely changes the direction of British foreign policy

Germany building aircraft carriers in the early 30s?

Rn very likely wins the argument for the return of the FAA

No AGNA? Herr Hitler not someone with whom the UK can do business etc...lots of Mothra right there!

 

[thaddeus]

Given the 'modern times' examples of german Jaguar and Tiger classes, sowjet Osa and Matka classes and swedisch Spica and Norköping classes I would render some fighting vessel in this class even in the early 1930 as a bonus with their even compared to the later Kriegsmarine S-boats increased fire power and seaworthyness.

(just IMO) the most important improvement would be minelaying capacity (from 6 - 8 to 23 - 24), maybe one of their overlooked duties?

I've always suggested a TB class off the diesel Bremse design, instead of the 1935 TB class, they could serve as a flotilla leader for the S-boats (the Bremse was almost identical in displacement to the 1939 TB class)

 

[Capt Thunderbolt]

Didn't both the He112 and 'later' He100 (didn't want to call it an He113 being a superstitions lot) have higher landing speeds than the 109?

Otherwise yes

A bit hard to quantify, with all the various engine and wing combinations.

Is stall speed more important to carrier landing vs landing speed for airfield??

Stall speed is much lower for He112 is around 120 vs Bf109 150 ???