Search found 180 matches

by RobertsonN
Tue Oct 22, 2019 7:12 pm
Forum: Bismarck General Discussion
Topic: bismark-after torpedo hit
Replies: 90
Views: 2844

Re: bismark-after torpedo hit

Under-bottom torpedo hits, if they can be arranged (now fairly easy, in the 1940's very difficult) are indeed, potentially lethal regardless of side protection. Bismarck's side protection system was certainly not inept in concept, but it certainly wasn't perfect either. The biggest problem lie in t...
by RobertsonN
Sat Aug 31, 2019 9:34 am
Forum: Bismarck General Discussion
Topic: It's up to you
Replies: 3
Views: 565

Re: It's up to you

Over on the NavWeaps Forum this kind of explosion used to be fairly regular. Each time followed by a silence for a few days. Then one or two people made posts and soon things were back to normal,

Neil Robertson
by RobertsonN
Sun Aug 11, 2019 4:05 pm
Forum: Bismarck General Discussion
Topic: Battleship Bismarck: A Design and Operational History
Replies: 59
Views: 9688

Re: Battleship Bismarck: A Design and Operational History

I am now close to the end of this book, having started on June 25. The authors remark that there was difficulty in damaging Bismarck at very close range because of the sea state. Waves were six to eight meters high. This would have meant that under a range of 5000 m, the last 100+ m of the shell tra...
by RobertsonN
Sat Aug 03, 2019 1:07 pm
Forum: Bismarck General Discussion
Topic: Battleship Bismarck: A Design and Operational History
Replies: 59
Views: 9688

Re: Battleship Bismarck: A Design and Operational History

My main criticism of this book so far in reading it has been the lack of German evaluations of the ship, particularly in relation to foreign ships. I have now come across some comment on this subject, although it is brief and made in passing in the operational history sections. The authors make no c...
by RobertsonN
Mon Jul 29, 2019 4:05 pm
Forum: Bismarck General Discussion
Topic: 3-shaft propulsion
Replies: 115
Views: 3905

Re: Battleship Bismarck: A Design and Operational History

Three shafts weigh less than four. Breyer in Marine Arsenal No. 2, p. 6, gives the weight of the shafts and propellers in Gneisenau as 366 mt. So one shaft with its propeller weighed about 120 mt,

Neil Robertson
by RobertsonN
Fri Jul 26, 2019 10:24 am
Forum: Bismarck General Discussion
Topic: Battleship Bismarck: A Design and Operational History
Replies: 59
Views: 9688

Re: Battleship Bismarck: A Design and Operational History

I did have a look in my copy of Axis Battleships again and can confirm that this is the more complete book as far as the design of the ship is concerned. Mind you, I did notice one glaring contradiction in it. It says the armor was intended to provide protection between 20000 and 30000 m. Later on, ...
by RobertsonN
Thu Jul 25, 2019 4:16 pm
Forum: Bismarck General Discussion
Topic: Battleship Bismarck: A Design and Operational History
Replies: 59
Views: 9688

Re: Battleship Bismarck: A Design and Operational History

Another omission in this book is any reference to the post-Jutland German designs for ships of the line and 'fast large fighting ships'. These were mostly of about the same size as Bismarck. While the ships of the line featured the usual sloping armor deck, the fast large fighting ships omitted this...
by RobertsonN
Thu Jul 25, 2019 10:27 am
Forum: Bismarck General Discussion
Topic: Battleship Bismarck: A Design and Operational History
Replies: 59
Views: 9688

Re: Battleship Bismarck: A Design and Operational History

I would agree mostly with this assessment. The book is very strong on the operational story and the wreck. There are many excellent photos of the ship as it is now, mainly taken during the Cameron 2002 expedition. There is a fairly detailed reconstruction of the probable trajectory of the ship from ...
by RobertsonN
Tue May 21, 2019 9:39 pm
Forum: Bismarck General Discussion
Topic: On the Origins of Scaling
Replies: 13
Views: 789

Re: On the Origins of Scaling

It is often helpful in developing one's own ideas to talk to other people about them as here. Looking at support for the ideas I am putting forward in Gkdos100: For the 38 cm APC sees against KC n/A that the curves are very close together at 90 deg obliquity (normal) are very close together (a diffe...
by RobertsonN
Tue May 21, 2019 8:27 pm
Forum: Bismarck General Discussion
Topic: On the Origins of Scaling
Replies: 13
Views: 789

Re: On the Origins of Scaling

The scaling effect in going from 15 in to 16 in is likely to be distinctly less than the difference in impact velocity, although it depends a bit on what the range is as the 15 in will slow down more than the 16 in as range increases, reducing that 100 m/s difference. In this example the 15 in proba...
by RobertsonN
Tue May 21, 2019 6:24 pm
Forum: Bismarck General Discussion
Topic: On the Origins of Scaling
Replies: 13
Views: 789

Re: On the Origins of Scaling

Could you give a reference for that opinion you have read? I have never come across anything suggesting that bigger plugs were in general thrown out of thick KC plates by large calibre shells than was the case for smaller shells against thinner armor. IIRC in US tests of 14 in APC against ultrathick...
by RobertsonN
Fri May 17, 2019 10:20 pm
Forum: Bismarck General Discussion
Topic: On the Origins of Scaling
Replies: 13
Views: 789

Re: On the Origins of Scaling

Normal Attack and Scaling At normal attack it is axial forces causing compressive failure that endanger the shell including shock-induced shatter and inertia-induced shatter sometimes called secondary shatter as it occurs later than shock-induced shatter provided that it has not happened. With shoc...
by RobertsonN
Fri May 17, 2019 9:55 pm
Forum: Bismarck General Discussion
Topic: On the Origins of Scaling
Replies: 13
Views: 789

Angle Attack: Breakage Mechanisms and Scaling On p. 93 of the USNMTE Gercke wrote: 'Because of the stresses caused by the transverse forces the projectile must be given a hardness gradient from the nose to the base in order to withstand them. In order to limit the value of M1 [the moment of force c...
by RobertsonN
Fri May 17, 2019 9:11 pm
Forum: Bismarck General Discussion
Topic: On the Origins of Scaling
Replies: 13
Views: 789

On the Origins of Scaling

Summary Scaling is the feature of armor penetration curves which show a reduced critical velocity with increase in calibre for given T/D (plate thickness/shell calibre) ratio. Scaling is a feature of the penetration curves given in Gkdos100. Nathan Okun attributed this scaling to a reduced ability ...
by RobertsonN
Tue May 07, 2019 7:39 pm
Forum: Bismarck General Discussion
Topic: Some questions regarding Bismarck's armor scheme
Replies: 17
Views: 1376

Re: Some questions regarding Bismarck's armor scheme

It is perhaps useful to study, as in Figs 12 and 13 of the paper by Hoyer (which appears elsewhere on this site), the curves showing the critical velocities needed for penetration and that of the projectile terminal velocity with range and inclination. If the critical velocity is below the terminal...