Bismarck with 3 triple turrets

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Javier L.
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Bismarck with 3 triple turrets

Post by Javier L. »

What would you think of a Bismarck with 3 triple turrets instead of 4 double turrets? I know the Germans never constructed a triple turret with 38 cm guns but let's just think about it. Maintaining the same hull dimensions, don't you think this new design would save a lot of weight, make the ship either a bit faster or a bit better protected, and gain an additional gun? :think:
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Post by Bgile »

Those are the reasons why some navies did that, but there are reasons for having 4 twin turrets also and that is why the Germans did it with Bismarck and the British did it with most of their ships. Even the KGV class had an even number of guns. It was an ongoing debate throughout the world's navies.

With respect to triple turrets, the US seems to have got it right, but the Nelson class had some trouble with awkward loading arrangements.
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Post by Javier L. »

Hello Bgile,

I brought this subject because I made some calculations and I think a Bismarck with 3 triple turrets wouldn't save much weight at all. Let me explain my reasons.

1) Each double turret of the Bismarck had a weight of 1.056 tons. There were four turrets so that makes a total weight of 4,224 tons.

2) The Germans never constructed a triple turret with 38 cm guns so all we can do is guess what the weight of such turret would be. Here are the weights of triple turrets of other countries:

40.6 cm triple turret of North Carolina 1,460 mt.
40.6 cm triple turret of Nelson: 1,503.7 mt.
38 cm triple turret of Litorios: 1.595 mt.
40.6 cm triple turret of Iowa: 1,735.4 mt.

Considereing that Bismarck turrets were particularly big when compared with other double turrets, I think it would be fair to assume that an hypothetical german triple turret of 38 cm could weight about 1,500 mt.

3) The result is:

4 double turrets of 38 cm weight: 1.056 x 4 = 4,224 mt.
3 triple turrets of 38 cm weight: 1.500 x 3 = 4,500 mt.

So we find that the 3 triple turrets weight 275 mt more that the 4 double turrets.

4) Of course this is not all since the weight of the barbettes counts too. Ok let’s make more calculations.
The length of a circle equals = number PI (3.1416) multiplied by the diameter of the circle. So, the diameter of Bismarck barbettes was 10.5 m. that multiplied by 3.1416 equals 32.98 m., and that multiplied again by a height of 5.2 m. (for barbettes A and D) gives a result of an area of 171.5 square meters…and multiplied by 8 m. (for the elevated barbettes B and C) gives and area of about 254 square meters. If we add everything we find that the combined area of the 4 Bismarck barbettes is (171.5 x 2) + (264 x 2) = 871 square meters.

Now let’s calculate the area of the hypothetical barbettes for the 3 triple turrets. Since we don’t know the diameter of these barbettes we can only guess. I gave a diameter of 12 meters (only 1.5 meters more than the barbetes for double turrets). The results were the following:
(207.35 x 2) + 301.6 = 716.3 square meters.

5) So here we find that the 4 double turrets have 154.7 (871-716.3) square meters more that the 3 triple turrets. Round up to 155 square meters. Now the key question is: what would be the weight of 155 square meters of German KC armor with a thickness of 220-340 mm? This is important because if it is less than 275 mt (see number 3 reference above) then we find that the weights more or less cancel each other.

6) But this is not all. When we remove the 4th Bismarck turret we must cover the cylindrical hole left by it. The area of that “hole” is = (10.5 / 2)² x 3.1416 = 86.6 square meters. That is 86.6 square meters of 50 mm thick upper deck that must be covered + 86.6 square meters of battery deck that must be covered + 86.6 square meters of 100 mm thick armor deck that must be covered. And all that must have a considerable weight too.

7) Because all of the above reasons I think that a Bismarck with 3 triple turrets wouldn’t have saved weight at all when compared with the real Bismarck of 4 double turrets. And there is more, in the hypothetical 3 triple turret design, because of the space left by the 4th double turret, we could now add 4 additional boilers in 2 separate compartments, (not necessarily in the same section as the missing turret because a different internal hull distribution could be made). That additional boilers could make the ship a bit faster but adding more weight too. And I don’t think the side belt could be shortened either in the 3 triple turret design because it would need to cover the additional machinery.

So I don’t see much benefit at all from a Bismarck with 4 double turrets and a Bismarck with 3 triple turrets:

. . . . . . . .4 double turret Bismarck . . . . . 3 triple turret Bismarck:
weight:. . . . . . . . .50,000 tons. . . . . . . . . . . about the same
speed: . . . . . . . . . 30 knots . . . . . . . . . . . . . . . . 31-32 knots because of additional boilers
guns:. . . . . . . . . . . 8 x 38 cm . . . . . . . . . . . . . . 9 x 38 cm
turrets: . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . 3

What do you all think? Does it make sense?

Javi
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Post by marcelo_malara »

You can shorten the ship if you use three turrets, that would save weight in armour and structure, which in turn means you need less power, saving further weight in machinery.
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Post by Matthias »

Dunno.If they kept the ship 36 meters large, they needed anyway a lenght of at least 250 meters to have a right lenght/width ratio.On the contrary the ship would have been too large and then she should have had difficoulties of manouvre and navigation in a raw sea, and in speed.Remember that keel's measures and form are mostly an important factor in a speed ship and manouvrability.;)
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Post by Bgile »

marcelo_malara wrote:You can shorten the ship if you use three turrets, that would save weight in armour and structure, which in turn means you need less power, saving further weight in machinery.
This is not true. Adding length can increase speed. That is why Iowa class were so long with very "fine" bow. Hydrodynamics.

One advantage of having fewer turrets is that you have more useable deck space for the secondary and AAA batteries. The US considered that to be very important, for good reason - US battleships were major fleet AAA ships.

It's all a compromise. Smaller barbettes give more room for torpedo protection space.

And on and on, LOL. Both systems have advantages.
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Post by marcelo_malara »

You are right, but 200 mts are more than enough for 30 kts.
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Post by Javier L. »

My calculations were based on a Bismarck with 3 triple turrets but with the same hull dimensions: 250 x 36 meters.

Of course, the hypothetical 3 triple turret design could be shortened. If we take away Section IV the ship is shortened by about 15 meters I think. The result is a ship with the same machinery but less displacement. But the problem I think is that I'm not sure the ratio lenght/beam (235 x 36 meters) would be appropriate.

I think that keeping the same hull dimensions would be a better choice rather than shorten the hull.

. . . . . . . .4 double turret Bismarck . . . 3 triple turret Bismarck . . . Shortened 3 triple Bismarck
weight:. . . . . . . . .50,000 tons. . . . . . . . . . about the same. . . . . . . . . 45,000 tons
speed: . . . . . . . . . 30 knots . . . . . . . . . . . . . . . 31-32. . . . . . . . . . . . . . . . 30 ?
guns:. . . . . . . . . . . 8 x 38 cm . . . . . . . . . . . . . 9 x 38 cm. . . . . . . . . . . . . 9 x 38 cm
turrets: . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . 3. . . . . . . . . . . . . . . . . . 3
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Post by marcelo_malara »

So you may reduce the lenght to 235 mts and the beam to 33.5 mts to maintain the lenght/beam ratio. That will give a grown North Carolina, and with 130000 hp you may get 29 knt, but I think that the reduced underwater volume will no be enough to float a hull with increased armour.
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Post by Matthias »

You should also change the machinery.A 36 mt beam give you the space to host 12 boilers, but if you reduce the beam to 32 mt, for example, like in Iowa class, you have to change the steam production sistem in order to fill the space you have properly.
As you stated correctly speed in knots is directly proportional to the waterline lenght/beam width ratio, so to obtain a faster ship, at least in teory you should build a hull with the highest ratio as possible (think to the regatta vessels, how they are made...;)).
But in a 50.000 tons ship, a longer hull gives problems of maneuverability, expecially with a raw sea, like Hood had.
Evidently, if german engineers projected Bismarck and Tirpitz with four twin turrets and 251 meters long, the main reason was to obtain a ship that would have had a good equilibrium between fire power, speed, protection and "agility".
I think they fulfilled their aims.;)
Americans did the same with Iowa class and three trice turrets, but this is another story...;)
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Post by 1Big Rich »

But in a 50.000 tons ship, a longer hull gives problems of maneuverability
Not necessarily. The Iowas for example, had twin rudders and were very handy. The Fletcher class DD turning radius was actually GREATER than that of the BBs. But manuverability was probably the worst characteristic of the Fletchers.

Bismarck too, had a very sensative helm, where even small changes to the wheel would alter her course. I suspect, but have never had it confirmed, that this was due to the placement of the twin rudders between the races of all three props, but I digress.

BTW, if you're interested, we've had some speculation on what triple turret Bismarck would look like over on the Warship Projects board, in the "Own Design" forum. Here's a direct link:

http://www.phpbbplanet.com/forum/viewto ... ipprojects

Regards,

Big Rich
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Post by Matthias »

1Big Rich wrote: Not necessarily. The Iowas for example, had twin rudders and were very handy. The Fletcher class DD turning radius was actually GREATER than that of the BBs. But manuverability was probably the worst characteristic of the Fletchers.
But they also had four screw and 212.000 HP of engine power.I didn't mean that the hull lenght is the only parameter for the maneuverability of a ship, it's only one.Also, Iowa and Bismarck class had very different hulls...;)
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Post by ontheslipway »

The Iowas for example, had twin rudders and were very handy. The Fletcher class DD turning radius was actually GREATER than that of the BBs. But manuverability was probably the worst characteristic of the Fletchers.
This may also indicate that the Iowa's lost more speed than the Fletchers during a turn.
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Post by 1Big Rich »

I didn't mean that the hull lenght is the only parameter for the maneuverability of a ship, it's only one.Also, Iowa and Bismarck class had very different hulls...
I agree, Bis and Iowa have very different hullforms, yet their both handy ships. About the only thing they have in common hull wise is twin rudders...
This may also indicate that the Iowa's lost more speed than the Fletchers during a turn.
I don't know about that, foeth. While there is a lot of hull, that is also a lot of inertia for friction overcome. I think Fletchers single rudder might have more to do with it.

The post-war solutions for the Fletchers was the fitting of a larger rudder to improve manueverability. The Alaskas were also no known as particularly handy ships, and IIRC, they had a single rudder as well.

Regards,

Big Rich
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Post by Karl Heidenreich »

After visiting the link 1 Big Rich displayed for us I wonder this:
Why 3 triple turrets and shortening the ship? Instead of that there can be an accomodation for Four Triple Turrets and then having the undisputed mightiest warship @ 1941. It´s obvious then that the ship might be slightly larger but that can help to accomodate aditional boilers too. The speed of 30 knots can be maintained, though, and maybe for hydrodinamics the relation can help Bismarck to be even faster. Probably that will mean a four propeller - four shaft arragement.
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