Search found 1164 matches

by marcelo_malara
Sat Sep 14, 2019 5:08 pm
Forum: Naval Propulsion
Topic: Lurrson effect rudders for Bismarck?
Replies: 2
Views: 103

Re: Lurrson effect rudders for Bismarck?

Hi, it seems an effect applicable to small vessels, the stern is lifted a little and this reduces resistance. Nowadays we have trim tabs for the same. Don´t think that a ship of the Bismarck size would benefit from it.

Regards
by marcelo_malara
Sat Sep 14, 2019 5:06 pm
Forum: Books and Reference
Topic: Axis ships damage reports
Replies: 0
Views: 51

Axis ships damage reports

Hi guys. I have a document titled Ships Damaged or Sunk by Enemy Action which contains brief descriptions of the damage received by the RN ships in WWII. In the Hyperwar web site I can find the same for the USN.

Is there anything like this for Italians and Japanese vessels?

Regards
by marcelo_malara
Sun Aug 25, 2019 2:15 am
Forum: Bismarck General Discussion
Topic: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940
Replies: 28
Views: 753

Re: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940

Guys, I made some rough and very simplified calculations. Length...Beam..Diagonal...Water plane 250...…..36......126,29......4500 ……...t...…….Density....Volume dspl…..Draught...……..Wetted area....Resistance SW...40000...1,025....39024,39024.....8,672086721...8880,791328....9102,811 FW...40000...1,00...
by marcelo_malara
Sat Aug 24, 2019 11:01 pm
Forum: Bismarck General Discussion
Topic: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940
Replies: 28
Views: 753

Re: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940

The difference in density from 1.025 to 1.008 traduces in 13 cm in the draught, don´t know it would make much difference in speed.

Regards
by marcelo_malara
Fri Aug 23, 2019 10:01 pm
Forum: Bismarck General Discussion
Topic: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940
Replies: 28
Views: 753

Re: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940

There are some writings of D.K.Brown about this, shallow waters (meaning about 10-20 m) allows more speed, I think that 65 m is out of the effect.

Regards
by marcelo_malara
Fri Aug 23, 2019 3:23 am
Forum: Bismarck General Discussion
Topic: Battleship Bismarck: A Design and Operational History
Replies: 59
Views: 8982

Re: Battleship Bismarck: A Design and Operational History

What was the wind direction and speed that day?


Regards
by marcelo_malara
Thu Aug 22, 2019 12:12 am
Forum: Bismarck General Discussion
Topic: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940
Replies: 28
Views: 753

Re: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940

Yes, with a little algebra you can reorder the original formula to mine. The system seems to have worked well, because the contemporary Jane´s gave 28 feet draught for Bismarck and 24 for Scharnhorst. My theory is that it would not have been difficult for the would-be Allies to assess the correct di...
by marcelo_malara
Tue Aug 20, 2019 3:35 pm
Forum: Bismarck General Discussion
Topic: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940
Replies: 28
Views: 753

Re: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940

Let me try to understand this. There are 13 bars, I count how many are above water line, I take the next below water, in the photo would be number 9, so I start with 9 m, and add the decimeters to this. Right?
by marcelo_malara
Tue Aug 20, 2019 2:08 am
Forum: Naval Technology
Topic: Question For Bill Jurens & All Re Barrel Length
Replies: 8
Views: 812

Re: Question For Bill Jurens & All Re Barrel Length

I think that you can see a PIAT in action in the movie "A bridge to far". Anyway, I don´t follow much tank developments, but I believe that the guns have the upper hand here, with velocities in excess 5500 fps an APFSDS dart would penetrate about 80 cm of armour, far beyond any practical thickness. ...
by marcelo_malara
Tue Aug 20, 2019 1:55 am
Forum: Bismarck General Discussion
Topic: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940
Replies: 28
Views: 753

Re: FYI: meaning of the notation of the draft measurements during Bismarck’s trial runs, fall 1940

Wow, that is really tricky, why did they go to such complication? May be so the draught was not guessed at a foreign port? I always have the impression that German displacements above allowable limits were tolerated because it is relatively easy to guess a ships displacement knowing length, beam and...
by marcelo_malara
Fri Aug 16, 2019 12:28 am
Forum: Bismarck General Discussion
Topic: 3-shaft propulsion
Replies: 115
Views: 2724

Re: 3-shaft propulsion

Guys, I think that we have to go back to pre-Dreadnoughts days to understand this. I took a look at the Jane´s Warships of WWI. In those days the triple expansion reciprocating engine reigned supreme. Battleships displaced around 15000 t, and the machinery developed about 15000 hp. This was achieved...
by marcelo_malara
Thu Aug 15, 2019 7:00 pm
Forum: Bismarck General Discussion
Topic: 3-shaft propulsion
Replies: 115
Views: 2724

Re: 3-shaft propulsion

I took a look to the book "Distinguished liners" (a compilation of articles from the The Shipbuilder magazine related to passenger ships). It seems there were more cases of three shaft passenger ships than warships. The arrangements named are: -two reciprocating machines in wing shafts and a LP turb...
by marcelo_malara
Wed Aug 14, 2019 11:06 pm
Forum: Bismarck General Discussion
Topic: 3-shaft propulsion
Replies: 115
Views: 2724

Re: 3-shaft propulsion

The hard fact is that were far fewer three shafts warships than two or four shafted ones. I suspect that three shafts without gearing was a difficult proposition (because of the HP/LP tandem arrangement). Once the designers got used to 2 or 4 shafts, with the appearance of the gearing it would have ...
by marcelo_malara
Sun Aug 11, 2019 5:23 pm
Forum: Bismarck General Discussion
Topic: 3-shaft propulsion
Replies: 115
Views: 2724

Re: 3-shaft propulsion

Thanks Byron. As a side note, in Argentina we had two Dreadnoughts built in US in 1910, they had three shafts, I am trying to find out how the turbines were disposed, I had no plans but a photo of a cutaway model extant in the Naval Museum don´t show turbines in tandem.

Regards
by marcelo_malara
Sat Aug 10, 2019 5:08 pm
Forum: Bismarck General Discussion
Topic: 3-shaft propulsion
Replies: 115
Views: 2724

Re: 3-shaft propulsion

Thanks Marc! Incredible source! So basically is like Byron said, two turbines in tandem in each shaft. I think that technically it is more demanding, you have to perfectly align not one but two turbines to each shaft.


Regards