German light cruisers design: the aft turrets

[marcelo_malara]

Hi guys. An old question, which is the reason for the light German cruisers being built with two turrets aft?

Regards

[Tool1958]

Hi guys. An old question, which is the reason for the light German cruisers being built with two turrets aft?

Regards

Hi Marcello; - good question!

The translated German Wikipedia entry on the "Koenigsberg class" of light cruisers provides a plausible explanation.

“Armament - Interior view of the turret
To save weight, the Königsberg class decided to install three triple turrets instead of four double turrets - the first triple turrets in the German Navy.

One turret was at the front, two aft. This meant that only a third of the firepower was directed directly forward. One reason for this installation was the reconnaissance task that was taken into account during the design, as this would provide more firepower for a likely battle in retreat.

The two aft turrets were each moved about 2 m to port and starboard from the center line in order to be able to fire directly ahead past the superstructure.[2][3] In practice, however, this was not done because the muzzle pressure of the ship's cannons would have caused damage to the superstructure. For the first time in the German Navy, the K-class ships had a central fire control system.“

Source: Königsberg-Klasse (1929) https://de.wikipedia.org/wiki/K%C3%B6ni ... sse_(1929)

Regards Holger

[marcelo_malara]

Hi guys. An old question, which is the reason for the light German cruisers being built with two turrets aft?

Regards

Hi Marcello; - good question!

The translated German Wikipedia entry on the "Koenigsberg class" of light cruisers provides a plausible explanation.

“Armament - Interior view of the turret
To save weight, the Königsberg class decided to install three triple turrets instead of four double turrets - the first triple turrets in the German Navy.

One turret was at the front, two aft. This meant that only a third of the firepower was directed directly forward. One reason for this installation was the reconnaissance task that was taken into account during the design, as this would provide more firepower for a likely battle in retreat.

The two aft turrets were each moved about 2 m to port and starboard from the center line in order to be able to fire directly ahead past the superstructure.[2][3] In practice, however, this was not done because the muzzle pressure of the ship's cannons would have caused damage to the superstructure. For the first time in the German Navy, the K-class ships had a central fire control system.“

Source: Königsberg-Klasse (1929) https://de.wikipedia.org/wiki/K%C3%B6ni ... sse_(1929)

Regards Holger

Hi Holger. Yes, I know that, the classic explanation. But I was thinking if there wasn´t a not so easy explanation. May be something related to internal distribution, for example if both turrets are forward the superstructure needs to be placed further aft, and then the boilers would be further aft as well, and that would need a longer ship.

Regards

[Tool1958]

Hi Marcello

Yes, I know that, the classic explanation.

The reasons for installation two of the three 15-cm triple turrets on the stern of all five light cruisers of the German Navy up to 1945 were, in my opinion, only due to the defensive operating doctrine for reconnaissance tasks. This means to position the main focus of the artillery on the stern when in contact with enemy naval forces and the resulting reconnaissance for the retreat battle.

Perhaps one should also consider that this unusual Design, with emphasis on the firepower for a retreating battle, was also due to the inferior strength of the fleet and the lack of naval bases overseas?

But I was thinking if there wasn´t a not so easy explanation. May be something related to internal distribution, for example if both turrets are forward the superstructure needs to be placed further aft, and then the boilers would be further aft as well, and that would need a longer ship.

Is there any evidence for this?

Regards Holger

[marcelo_malara]

Hi Marcello

But I was thinking if there wasn´t a not so easy explanation. May be something related to internal distribution, for example if both turrets are forward the superstructure needs to be placed further aft, and then the boilers would be further aft as well, and that would need a longer ship.

Is there any evidence for this?

Regards Holger

Yes! Look at this plan from KM Nurnberg, the "stauung" deck. Go back to the aft turbine room, on the port side. Note that this turbine can not be placed further aft, because the lines of the ship are thinner toward the stern and the turbine casing could not be accommodated. Then the placement of the machinery and boilers is fixed by this. Then go to the longitudinal section plan, towards the superstructure, A turret and bow. The superstructure can not be placed much further aft to accommodate a B turret in front of it, because so the superstructure would be on top on the forward boiler room, and would interfere with the uptakes and stack. A B turret on the bow would need increasing the length of the ship,

May be all this is caused by the presence of the center diesel powered shaft. If this was eliminated, and a pure steam turbine two shaft adopted, the turbines (may be) could be placed more near the center of the ship, further aft, and space in deck towards the bow found to place a B turret.






https://postimg.cc/7bWH3r1S



https://postimg.cc/m1M519NX

[Tool1958]

Hi Marcello

But I was thinking if there wasn´t a not so easy explanation. May be something related to internal distribution, for example if both turrets are forward the superstructure needs to be placed further aft, and then the boilers would be further aft as well, and that would need a longer ship.

Is there any evidence for this?

Regards Holger

Yes! Look at this plan from KM Nurnberg, the "stauung" deck. Go back to the aft turbine room, on the port side. Note that this turbine can not be placed further aft, because the lines of the ship are thinner toward the stern and the turbine casing could not be accommodated. Then the placement of the machinery and boilers is fixed by this. Then go to the longitudinal section plan, towards the superstructure, A turret and bow. The superstructure can not be placed much further aft to accommodate a B turret in front of it, because so the superstructure would be on top on the forward boiler room, and would interfere with the uptakes and stack. A B turret on the bow would need increasing the length of the ship,

May be all this is caused by the presence of the center diesel powered shaft. If this was eliminated, and a pure steam turbine two shaft adopted, the turbines (may be) could be placed more near the center of the ship, further aft, and space in deck towards the bow found to place a B turret.

Hi Marello, thanks for posting. Great scale of this drawings in 1:100!

At this point I have to withdraw from the discussion. In my point of view, here, someone can only contribute effectively to this subject if he or she has a degree in marine engineering with a specific focus on plant construction.

Reagrds Holger