Bismarck Speed

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delcyros
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Re: Bismarck Speed

Post by delcyros »

But You agree that there is a difference between "erreicht" (=achieved) and "errechnet" (=calculated)?
The authors of this report had full access to trial data. More informations such as displacement and water depth of the trials are needed to attempt to reconstruct the speed/displacement functions of this ship but I take it from the report that a speed of 30.6 kts was achieved by BISMARCK even though the conditions remain unknown.
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Herr Nilsson
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Re: Bismarck Speed

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delcyros wrote:But You agree that there is a difference between "erreicht" (=achieved) and "errechnet" (=calculated)?
Yes, I agree.
delcyros wrote:The authors of this report had full access to trial data. More informations such as displacement and water depth of the trials are needed to attempt to reconstruct the speed/displacement functions of this ship but I take it from the report that a speed of 30.6 kts was achieved by BISMARCK even though the conditions remain unknown.
The authors didn't even have access to the correct displacement data of Bismarck. :(
Maybe Bismarck achieved 30.6 kts, but we can't compare it to anything without additional data.
IMHO Bismarck was possibly able to run 30.1 kts at 150.000 SHP at 75% payload. It's just an educated guess, but I think anything more would need much more SHP.
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
delcyros
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Re: Bismarck Speed

Post by delcyros »

I agree. It´s impossible to compare this with other data without further information.
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Re: Bismarck Speed

Post by delcyros »

Aside from the reported trial speed of 28.374kts at ~117,000 SHP, are there any different speed / power data aviable for BISMARCK or TIRPITZ? I mean, from fuel consumption trials including as far as displacement was known...
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Herr Nilsson
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Re: Bismarck Speed

Post by Herr Nilsson »

Eureka! There's an original document of the EKK (Erprobungskommando Kriegsschiffneubauten) with a comparison of the speed/power curves of Tirpitz and Bismarck. It clearly states that Bismarck made 30.1 kts at 150,170 SHP and 75% payload.
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Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
delcyros
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Re: Bismarck Speed

Post by delcyros »

A great find, congratulations.

Do I have it to take that the document includes more speed figures than the top speed? If so -are there data´s aviable at lower speed, too?
And what is meant with 75% -a range in between 46,934 and 47,683ts, I guess?
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José M. Rico
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Re: Bismarck Speed

Post by José M. Rico »

Herr Nilsson wrote:Eureka! There's an original document of the EKK (Erprobungskommando Kriegsschiffneubauten) with a comparison of the speed/power curves of Tirpitz and Bismarck. It clearly states that Bismarck made 30.1 kts at 150,170 SHP and 75% payload.
That has to be the data from the Meilenfahrten of 23 October 1940, I believe.
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Re: Bismarck Speed

Post by Herr Nilsson »

@delcyros
There are two complete speed/power curves (each for one ship), starting from 7.5 kts and 2000 SHP up to 30+ kts. On these curves are markings (puncture with a small circles) for the speed/power pairs of values of the trial runs. There are only the 0% and 100%-weights of Tirpitz. Compared to that the weight of Bismarck would be 49385 mt at 75%.

@José
The last marking on the speed power curve of Bismarck is a bit more than 150,000 SHP. As we know there was a trial run with 150,170 SHP. Therefore my asumption was that it was this trial run.
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
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Re: Bismarck Speed

Post by alecsandros »

@Herr Nilson:

Could you please tell us what was Tirpitz speed at 53000t ? (100% load)
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Re: Bismarck Speed

Post by dunmunro »

Herr Nilsson wrote:@delcyros
There are two complete speed/power curves (each for one ship), starting from 7.5 kts and 2000 SHP up to 30+ kts. On these curves are markings (puncture with a small circles) for the speed/power pairs of values of the trial runs. There are only the 0% and 100%-weights of Tirpitz. Compared to that the weight of Bismarck would be 49385 mt at 75%.

@José
The last marking on the speed power curve of Bismarck is a bit more than 150,000 SHP. As we know there was a trial run with 150,170 SHP. Therefore my asumption was that it was this trial run.
These loading weights are not well defined, and IMHO do not correspond to actual displacements, but are a percentage of design full load, which was considerably less than their actual full load values. I wonder how the power curve compares to my estimate:

Image
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José M. Rico
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Re: Bismarck Speed

Post by José M. Rico »

dunmunro,
Bismarck was faster than KGV. Get over it.
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Herr Nilsson
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Re: Bismarck Speed

Post by Herr Nilsson »

dunmunro wrote: These loading weights are not well defined, and IMHO do not correspond to actual displacements, but are a percentage of design full load, which was considerably less than their actual full load values.
I'm sorry Duncan, but the loading weights are well defined:
displacement without payload and 100% payload
displacement without payload and 100% payload
1.jpg (94.77 KiB) Viewed 4409 times
The values for Bismarck according the weight list from April 30th 1940 are:
Displacement without payload: 43356 mt
Displacement with 100% payload: 51395 mt
75% payload
75% payload
2.jpg (99.51 KiB) Viewed 4409 times
Regards

Marc

"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
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Re: Bismarck Speed

Post by alecsandros »

José M. Rico wrote:dunmunro,
Bismarck was faster than KGV. Get over it.
:clap:
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Re: Bismarck Speed

Post by dunmunro »

There's still no proof of that... :negative:
delcyros
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Re: Bismarck Speed

Post by delcyros »

@delcyros
There are two complete speed/power curves (each for one ship), starting from 7.5 kts and 2000 SHP up to 30+ kts. On these curves are markings (puncture with a small circles) for the speed/power pairs of values of the trial runs. There are only the 0% and 100%-weights of Tirpitz. Compared to that the weight of Bismarck would be 49385 mt at 75%.
With the 7.5 kts datapoint I was able to extrapolate the required speed to make 30.6 kts according to the MMF-model. The prediction for this speed is 161,500 SHP required but more datapoints would allow better model prediction. This may or may not be in within the powerplants capabilities for overload power (I don´t know).
The dataset from TIRPITZ with 100% runs would also allow to factor in displacement changes more precisely, namely to verify them with the KM set calculations.
Do You happen to know where exactly the measured mile was taken from? I guess from Pillau / Neukrug but which of the three ranges? The 25m, the 34m or the 65m range?

Thanks in advance,
delc
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