Bismarck range

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Bismarck range

Post by TTTT »

Bismarck/Tirpitz gets a lot of flak for for their supposedly short range.

If we compare range to the best of the US battleships, the North Carolina (Iowa had shorter range), this seems justified. North Carolina could go 17,450 nmi at 15 knots in 1941 (less later), while Bismarck could "only" go 9,280 nmi at 16 knots.

However, at higher speed a different picture emerges; North Carolina could only go 5,740 nmi at 25 knots, while Bismarck could go 6,640 nmi at 24 knots!

And Bismarck/Tirpitz has better range at all speeds compared to any European battleship.

Any thoughts on this?
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Re: Bismarck range

Post by Byron Angel »

North Carolina’s cruising range @ 24 kts can probably be checked in the FTP-218 pages on I-biblio.

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Re: Bismarck range

Post by marcelo_malara »

Fuel consumption is fairly linear with machinery horsepower, but machinery horsepower varies approximatly with the cube of the speed, so in this discussions care has to be taken with the speed. The hyperwar page mentions for BB 55 a max range of 15000 nm at 13 kt.
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Re: Bismarck range

Post by marcelo_malara »

At 24 kt about 5000 nm.
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Re: Bismarck range

Post by marcelo_malara »

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Re: Bismarck range

Post by TTTT »

Thanks, great source!

So, Bismarck vs. US battleships

16 knots
Bismarck: 9,280 nmi
North Carolina: 13,000
South Dakota: 15,110
Iowa: 15,000

24 knots
Bismarck: 6,648 nmi
North Carolina: 6,140
South Dakota: 6,860
Iowa: 10,000

27 knots
Bismarck: n/a
North Carolina: 3,640 nmi, top speed
South Dakota: 3,900, top speed
Iowa: 7,910

28 knots
Bismarck: 4,500 nmi
Iowa: 6,970

30 knots
Bismarck: n/a
Iowa: 5,000

I was wrong about NC being the best US BB, Iowa is clearly the best. Even so, Bismarck did well against NC and SD at higher speed.
Last edited by TTTT on Fri Sep 03, 2021 9:21 pm, edited 1 time in total.
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Re: Bismarck range

Post by TTTT »

Tirpitz vs. late war US battleships

16 knots
Tirpitz: 9,280 nmi
North Carolina: 12,610
South Dakota: 14,290
Iowa: 14,000

24 knots
Tirpitz: 6,693 nmi
North Carolina: 5,700
South Dakota: 6,230
Iowa: 9,220

27 knots
Tirpitz: n/a
North Carolina: 3,470 (at 26,5 knots top speed)
South Dakota: 3,760 (at 26,5 knots top speed)
Iowa: 7,360

28 knots
Tirpitz: 4,728 nmi
Iowa: 6,500

30 knots
Tirpitz: n/a
Iowa: 4,710

All late war USA BBs were heavier than earlier in the war and had less range/radius and slightly less speed. It is possible that the same also was the same for Tirpitz? Again the German ship does well against NCand SD at high speed.
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Re: Bismarck range

Post by marcelo_malara »

We have already discussed this before. Bismarck´s machinery was not efficient, her consumption was 325 grams/hp/hour, whereas for example Massachusetts´ was 305.

Why was this so? Don´t know for sure, I suspect this. Bismarck´s steam plant was a high temperature/high pressure on, at 58 kg/cm2, while the American´s was a little lower at 40 kg/cm2. Bismarck´s steam would attain a higher steam jet velocity, what would need a matching high rpm turbine for efficiency, which Bismarck´s single reduction gearing could not reach. Bismarck´s HP turbine turns at 2800 rpm for 270 rpm in the shaft, whereas the USN´s BB double reduction gearing would turn at 6000 rpm for 185 rpm at the shaft. Bismarck´s machinery turns slow for a fast shaft and propeller, both combined is inefficient.
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Re: Bismarck range

Post by hans zurbriggen »

Hello,
Bismarck class boilers were the most advanced among all navies, working @ 450°C and 58 kg/cm2: for comparison Yamato's boilers worked @325°and 20 kg/cm2, Littorio's @ 325°and 25,8 kg/cm2, KGV class @ 325° and 28 kg/cm2, Richelieu's @ 350°and 27 kg/cm2, Iowa class @ 454°C and 39,72 kg/cm2. Bismarck's boilers were also light and very fast to start, but their own efficiency was "only" 80%, worse than US boilers.
The real problem (as correctly pointed out by Mr.Malara) of Bismarck class were however the large and slow turbines (due to single reduction German choice). They were unefficient and very badly coupled with such extreme steam conditions. A best choice would have been smaller turbines, rotating faster, with double reduction (or much smaller turbogenerators, turning much faster and producing electricity for electrical motors).

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Re: Bismarck range

Post by TTTT »

But still - the numbers show that Bismarck/Tirpitz had better range/radius than any European BB, and - at high speed - better range than 2 out of 3 US BB classes.
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Re: Bismarck range

Post by marcelo_malara »

That should be caused by her longer hull. Hull length determines wave making resistance, a longer hull has less resistance, so it would be no wonder that Bismarck could make the same speed with about the same or less power than the USN shorter BB, except of course for Iowa which was longer than all of them.
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Re: Bismarck range

Post by TTTT »

But Bismarck was also wider than all of them - with the exception of Yamato. Vanguard was as long as Bismarck - and Richelieu and Littorio not much shorter.
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Re: Bismarck range

Post by marcelo_malara »

Please post the hp vs speed numbers you can find for comparing.
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hans zurbriggen
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Re: Bismarck range

Post by hans zurbriggen »

Hello, see below numbers I have: however obtained speed and power depend on trials. I doubt these rough data can be used for any meaningful comparison. I would say that also hull shapes (in addition to length/beam)are key to determine speed and propulsion efficiency.

Bismarck: length 250.6 oa (wl 241,7), beam 36, 163.000 hp, 31 knots (peak) achieved by Tirpitz in extra-power @ very heavy load, 53.200 tons (design power was 138.000 hp for 29 knots)
Richelieu: length 247.85 (wl 242) , beam 33, 179,000 hp, 32.63 knots (peak) achieved in extra-power @ 43.800 tons quite light displ. (design was 155.000 hp for 32 knots, unknown displacement; extra-power designed for 175.000 hp)
Littorio: length 237.7 (wl 232,4), beam 32.4 (wl),139,561 hp, 31.4 knots (peak speed obtained by Vittorio Veneto at trials @ extremely light displ.= 41.900 tons); extra-power was 160.000 hp (never tested as war was declared and fears of potential damages prevented it)

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Re: Bismarck range

Post by TTTT »

Richelieu could "only" do 30 knots after her refit in 1943. According to Wikipedia "typical" top speed of Littorio-class in operations was 28 knots.

I guess fuel capacity give some perspective of how effective the machinery was.

Max fuel capacity:
Bismarck: 8,294 tons (this site) (7,400 Wikipedia)
Tirpitz: 8,297 (this site) (7,780 Wikipedia)
North Carolina: 7,554
South Dakota: 6,768
Iowa: 9,033

This seems to indicate that the US machinery indeed was somewhat more efficient (unless the numbers from Wikipedia is correct?).
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