Alternate warship design

Redbeard

Banned
As a sideshow in my Baltic Empire TL I've puzzled with a Royal Hansa Jagtkreutser design (Literally: "Hunting cruiser" like in Jagdpanzer - the homemade spelling is the 20th century Hansa semi Platdeutsch language). The Royal Hansa includes the Baltic coastlines, Scandinavia, N.Germany, Netherlands and GB.

The design is commissioned in 1940 or 41 and follows a line of battlecruisers built since early 20th century.

The Hansa had like everybody else started building Dreadnoughts, but had soon realised that the global interests of the Royal Hansa could not be trusted to lines of slow Dreadnoughts relying on the enemy seeking battle by themselves. So a smaller number of big and powerful battlecruisers had been built and in the Great War of 1917-20 these had, aided by wireless and aerial recon., first defeated the CSA Atlantic Fleet in the Caribean and next a French/Spanish Fleet trying to invade the Azores and which thought the Hansa Fleet was still in the Caribean.

As the Russians collapsed simultaneously with the Atlantic defeats, the anti-Hansa colalition practically fell apart. This was in the last moment for the Hansa and her allies (Central and South German states, A-H and Romania), who were hard pressed on land in both Europe and Canada and had Japan lurking in the Far East.

But anyway, at the peace conference in Geneva, it was also agreed to limit the naval race by parity (600.000 tons) between the Hansa and the combined fleets of France, Spain and CSA and a general 35.000 ton limit on capital ships. Russia was in chaos, and the Japanese were not part of the armistice - but also frightfully short of money. Italy and A-H were to have mutual parity. The Hansa was allowed to use part of her allowance in the semi-independent Dominions of Togo and India (each got a 30.000 ton BC with 12 30cm guns).

The first Hansa design after the Geneva Treaty was two 30 knot ships with two 41cm triples forward, commissioned in the late 1920's (Leopard and Panther). The design was seen as the final rejection of the ship-of-the-line tactic, and instead the idea was to have ships with superior speed to engage frontally and from individual directions (and in combintion with other ship types and airattack). This also put different demands on protection, where emphasis was put on decks, turret fronts, barbettes and forward bulkheads. Weight could be saved on belts, which during battles were at a favourable inclination relative to enemy fire due to the frontal engagement tactic (Called: Cross my T - if you dare!).

During the first half of the 30's only smaller ships were built, but the Design Bureau had experimented with perfecting the Leopard design, and by 1937 improvements in especially machinery techniques, hydrodynamics, facehardened armour and welding had made it possible to add two more 41cm guns and two knots to a 35.000 design, without compromising protection. A big challenge had been to give all three turrets frontal arcs without having C turret to0 high. It was solved by accepting a very low freeboard at turret A, but with a marked sheer in front and comprehensive sealing of the turret against incoming seawater. A turret not being able to fire at 0 degrees over the bow was accepted as a cheap price for two extra 41cm.

The Borgmeister Nansen class, of which four were laid down in 1937, had the following specs:

227 m long, 32 m wide

35.000 tons, 140.000 shp, 32 knots

8 41 cm, 16 12 cm DP, 76 4 cm AA, 2-3 floatplanes

Belt: 28 cm inclined
Deck: 15 cm over citadel and rudders
Fwd. Bulkhead: 38cm
Turret fronts: 41 cm
Barbettes: max 38 cm

The leader of the Design Bureau had the opposition in the Combined City Council smell a scandal, when he said to a newspaper that a primary design critera was that if a design looked good it would be good too. The Union Lord Mayor saved the day by declaring that he totally agreed with the designer and had himself with considerable success followed the same principle in both love and politics.

Regards

Steffen Redbeard

BBjpeg.JPGa.jpg
 
Interesting. Why not place the twin 41cm turret in 'A' position. At least that would make the majority of your main armament capable of firing foward. It also may allow you finer lines toward the bow.
 

Redbeard

Banned
I have the twin in A position to save weight. A barbette is the tallest and as a twin I save several hundred tons compared to a triple (haven't got the calculations at hand). In a more narrow hull some of this would be offset by the need to strengthen the hull where the barbettes pierce the decks, but that is another reason for the relatively wide forward hull. The placing of the three barbettes so close will put a lot of strain on the hull and require additional strengtehning, but it is my idea that this is to be achieved by letting the armourplating be part of hull "stiffness" and by having extra bulkheads act as both hull strengther and subdivisions (as opposed to just filling in extra girders). OTOH the placing of the machinery aft will reduce shaft length which will both make a lot of things simpler and reduce weight.

I have made calculations on the total armour weight and apparently I can keep it under 30% of displacement with a 28cm belt, and even include some armoured tubing for wiring outside the citadel. Most WWII battleships had well over 30%, so I guess it would be possible to increase armour, but instead of a heavier belt I think I would go for extra splinterprotection.

I made the drawing in MS Paint, which follows the standard MS Office pack and is very easy to use, but also simple. The original Paint file takes up 26MB however, which is on the limit of what my laptop can handle, it simply refuses to do any more Paint work (!?), so I'll have to go for other solutions.

The Jagtkreutser in many ways can be called German, at least as far as my Royal Hansa has its origin in an 14th/15th century alliance between the King of Denmark and the Hansa and includes what is today North Germany as its cultural and linguistic heartland. The smaller German states in my TL has no coastlines, but A-H have a similar naval programme to their OTL, but this time realising the 10 35cm dreadnought design that in OTL never went beyond design.

I have a lot of paper sketches (and scratch built models) of both warships, planes and tanks (incl. WWII Austro-Hungarian tanks and planes) and will do more when I get the Paint or some other graphic programme to work.

Regards

Steffen Redbeard
 
Just noticed, doesn't the ship have a theoretical blind spot to the rear? Ie none of the heavy guns can cover the rear 75 to 90 degrees of the ship, only smaller guns. If I was the enemy captain I would try and stay to the rear of the ship as much as possible.

I would have at least one heavy turret on the rear of the ship.
 
Odin said:
Just noticed, doesn't the ship have a theoretical blind spot to the rear? Ie none of the heavy guns can cover the rear 75 to 90 degrees of the ship, only smaller guns. If I was the enemy captain I would try and stay to the rear of the ship as much as possible.

I would have at least one heavy turret on the rear of the ship.

Agree, and would not the high bow be a hindrance to the first turret? Atleast when target is close and stright ahead?

Otherwise, nice dawing skills. I have always wanted such skills but alas... :(
 

Redbeard

Banned
Odin said:
Just noticed, doesn't the ship have a theoretical blind spot to the rear? Ie none of the heavy guns can cover the rear 75 to 90 degrees of the ship, only smaller guns. If I was the enemy captain I would try and stay to the rear of the ship as much as possible.

I would have at least one heavy turret on the rear of the ship.

I would even say that shooting aft of the beam should be avoided due to blast effect (180 degree "blind" zone), but I don't consider that a problem in a ship with superior speed and supposed to be in a chasing rather than a chased role. These ships are built to choose the time and palce of action. In this context the all forward armament is not just a way in which to save weight (like in the Nelsons) but a doctrinal necessity that even give advantages protection wise (you can save on the belt). There is a slight disadvantage in turning your front or rear to the enemy, as salvoes normally have greater dispersion in length than in width.

In "normal" battleships with turrets both forward and aft shooting at any bearing but 90 degrees on the length axis would involve serious blast effect on superstructure, but in this design most of the forward 180 degrees will be blast free, the exception being low elevation shooting above the bow, which is likely to buckle the deck plating and shake lockers etc. on the deck below(was experienced in Nelson and Warspite in WWII).

Regards

Steffen Redbeard
 
Also, it's not like real life ships did not use an all forward layout.

The British Nelsons and the French Richeleu and Dunkerque class are the obvious examples and are not regarded as absolute failures.
Acceptable as long as the ship can fire all its main guns in a broadside, I'd say.
 
Redbeard said:
I have the twin in A position to save weight. A barbette is the tallest and as a twin I save several hundred tons compared to a triple (haven't got the calculations at hand). Steffen Redbeard

What do you mean in 'the twin in A position'? The twin is not in A position its in C position. The lettering starts from the bow.

Just would have considered the main gun arrangement as in the Pensacola class 'treaty' cruisers. For a class of Mexican battlecruisers I have always had 10-14in guns mounted in one quadruple and two triple turrets. The arrangement would have been 3-4-A-3 (Garzke format).
 
Random thought:

Would firing all main guns at once put high pressures on the keel, since they're confined a relativly same portion of the hull?
 

Redbeard

Banned
David S Poepoe said:
What do you mean in 'the twin in A position'? The twin is not in A position its in C position. The lettering starts from the bow.

Just would have considered the main gun arrangement as in the Pensacola class 'treaty' cruisers. For a class of Mexican battlecruisers I have always had 10-14in guns mounted in one quadruple and two triple turrets. The arrangement would have been 3-4-A-3 (Garzke format).

Ouch, sure it should have been C turret, I ought to know better :eek:

I believe the main reason for the arrangement in the Pensacolas was having the most narrow barbette at the most narrow place in the hull, giving strucural advantages. The barbettes and turrets on Pensacola anyway had very limitted armour making the potential weight difference marginal.

I considered a 41cm quadruple, but concluded that it would be too cumbersome on a 35.000 hull with reasonable length ratio. My first sketch was 7 41cm in 2-2-A-3, but if going for a head-on doctrine I could save enough on the belt to get an extra 41cm - and it looked better too :D

I guess your Mexican BC has a very narrow hull, otherwise it judging from the KGV's was possible to put a 14" quadruple in A position.

Regards

Steffen Redbeard
 

Redbeard

Banned
MBarry said:
Random thought:

Would firing all main guns at once put high pressures on the keel, since they're confined a relativly same portion of the hull?

I doubt the recoil in itself put that large stress on the hull, not with recoil systems etc. Anyway I like the idea of strengthening the hull and getting good subdivision at the same time, and will gladly pay with a thinner belt. The biggest effect on the hull is probably a long term bending if buoyancy in the turret area isn't big enough - but that is another reason for keeping the hull relatively wide here, even if it hydrodynamically isn't optimal. This was in many ways also the principle in the SoDak's, which had short "inefficient" hulls, but compensated for it through extra hp. Judging from the space allocated to boilers and turbines in the Jagtkreutser it ought to be possible to do the same + the effects of transom stern and bulbous bow.

Blast should not be overlooked. For instance the crew in the aft radar room on PoW got knocked out and injured by the aft 14" turret firing on a bearing forward of beam. But like I said in a previous post, I would prefer to be "blastfree" in the forward 180 degrees than only have a few degrees on the beams without blasteffects.

Regards

Steffen Redbeard
 
Great design.
Some nitpicking.
Traditionally the "German" choices for ship board guns were 38cm as main battery, 15cm as secondary. There were 12.8cm & 10.5cm guns for DP and they used 3.7cm or 2cm as heavy/light AA.
(By 1944-5, they had 5.5cm & 3cm AA to replace the 3.7/2cm)
The 4cm installation looks US - a duplicate of the quadruple mounts used in most USN ships.

It is interesting to see so much AA firepower on a ship designed in the late 1930's (for construction in the early 1940's)

What type of ships would these units be confronting?

It would be interesting if more ships focused on 'all forward' main batteries.
How many ship to ship engagements would be different if they could only fire forward?
 

Redbeard

Banned
Johnestauffer said:
Great design.
Some nitpicking.
Traditionally the "German" choices for ship board guns were 38cm as main battery, 15cm as secondary. There were 12.8cm & 10.5cm guns for DP and they used 3.7cm or 2cm as heavy/light AA.
(By 1944-5, they had 5.5cm & 3cm AA to replace the 3.7/2cm)
The 4cm installation looks US - a duplicate of the quadruple mounts used in most USN ships.

It is interesting to see so much AA firepower on a ship designed in the late 1930's (for construction in the early 1940's)

What type of ships would these units be confronting?

It would be interesting if more ships focused on 'all forward' main batteries.
How many ship to ship engagements would be different if they could only fire forward?

I had the Royal Hansa (AKA Royal Guilds of the North) start with 30cm guns on the pre-dreads and the first dreadnoughts and BC's and the next step being a 35cm gun on two four ship classes of BC's with 8 and 9 guns respectively. By this time the Hansa navy is sick and tired of always having guns a little smaller than the other guys (30,5 and 35,6 cm) so instead of taking the logic next step to a 40cm gun, they opt for a 41 cm gun in the next class of BC's. These are 35.000 ton ships with 6 guns in 2-2-A-2 arrangement, looking like like Renowns with a little wider hull. Anyway this Hansa really isn't very German in our perception of the term. N.Germany departed from S.Germany in 14th/15th century to have a common fate with Scandinavia, Baltic coast, Netherlands and, in my "extended version" with GB too. Although N.Germany is still the cultural and linguistic heartland, these "Germans" are clearly a seapeople, and would never find use for the limited task fleets of the second and third Reich's of OTL - so no special reason to expact any commonship in naval design and doctrines with the OTL Germans. In fact my main inspiration has been Jackie Fisher himself, the famous/mad First Sea Lord of the RN in early 20th century.

My reason for putting 40mm AA on board is mainly the excellent Swedish 40mm Bofors, in OTL production from the mid 30's, and in WWII also in allied lincense production. In my first experiments many years ago I tried a lot of arrangements/mounts, in order to exactly avoid something looking like the OTL USN quad mount. Some of my designs looked quite cool, but finally I had to admit, that in functionality nothing could beat the side by side in pairs arrangement of the USN quad. Not at least because of the relatively easy "feeding" of four round clips into the breeches. So any careful design would have to end with that result - no matter of the starting point.

As I have taken the advantage of having the 40mm Bofors available in this TL, I think it will also be the preferred light/medium AAA, but in the initial design probably not in those numbers. But with ample deckspace extra mounts can be quickly added. The 40mm being available from the start is however the reason why I have omitted 20mm. If you already have 40mm why go for 20mm? I have thought about adding a few 20mm quads (vierlings) as point defence, but decided that it, alongside with proton torpedoes and faser guns, was "too much of the goodies".

The ships they face are first the older surviving ships from before the 1920 war, pretty much the same as in OTL, but with for instance the French Normandies being completed, and with the IJN having a destinct Hansa design inspiration. After the Geneva Treaty the major powers are each allowed two over size ships. The CSN takes two modified Lexingtons, the IJN Kaga and Amagi, the French two oversize Normanies with 28knot speed and the Hansa two "Hood look-alikes" with 41cm guns but slightly slower (commissioning too late to take part in the 1920 war, but before the Geneva Conference).

The Hansa is accordingly allowed two 35.000 newbuilds before 1930 and completes two fast BB's with two triple 41 cm forward. The next generation is again French and they complete two Richelieu's (2x4 38cm) in mid 30's as the Dunkerques really have no meaning short of the OTL Panzerschiffe. Like in OTL most navies experiment with all forward armament, but only the French take it. Most significant is however, that like in OTL they do not fully optimise their all-forward ships, they still are protected for "broadside" battle. So while the Hansa does not have monopoly on all forward armament they do on optimising the protection and doctrines for it - but nobody really knows that yet. Had there been more, I guess we would have seen a lot of individual manoeuvring and with the fastest ship generally comming out on top. Fire control systems capable of making good solutions while manoeuvring would also be high priority.

IJN jumps right to Yamatos one more time, but the USN builds the "Hood type" design from September 1934: 35.000 tons, 710X101,5 feet, 30,5 knots, 8 16" (see Friedmann, US Battleships p235). The Italians and Austrians only focus on each other (no French-Italian antagony) and both complete a few slow but very heavily protected vessels for the Adriatic on top their OTL like early programmes.

The Hansa denounces all treaties in 1938, when the Soviets (under Trotsky) make a surprise attack on the Baltic provinces and succeed in advancing to the coast in many places, but before the end of 1938 is thrown back to the border and an armistice arranged through international mediation.

By this time the Borgmeister Nansen class is already laid down however and the Admiralty in general would prefer a lot of Nansens rather than a few of the 55.000 ton ships with 12 41cm in 3-3-A-3-3 proposed by the Design bureau. Other nations start on monster designs but none are completed when war breaks out again by October 1940. But this time the main Soviet attack is towards Romania and A-H and with the French, Italians, Spaniards, CSA and Japanese declaring war too.

The Nansens are mainly deployed in the Far East and I of course have a couple of them set up for a duel against a Yamato by 1942 or 43 - something like the wolfpack against the bull. My preferred place is the Balabac Strait between Borneo and Palawan (of the PI) during a Hansa invasion of PI(Spanish possession) - "Battle of Balabac Strait" sounds good anyway :D

Regards

Steffen Redbeard
 
I agree that with enough 40mm, you don't need 20mm. They were being removed from RN/USN ships by the end of the war as the 40mm was so much more effective.

Tony Williams: Military gun and ammunition website and discussion forum
 
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