late 1943 Tirpitz instead of Bismarck in May 1941

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lwd
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by lwd »

José M. Rico wrote: ... A question for all: Would the battlecruisers Queen Mary, Indefatigable, and Invencible blow up again in a second battle of Jutland?
Coming back to this for a second. Looking at the diagram at:
http://en.wikipedia.org/wiki/File:HMS_T ... s_1923.jpg
It looks to me like the turrets and barbetts comprise about 20% of the horizontal target area of Tiger from a broadside perspective. If she is at an angle this would increase until they start to overlap signficanlty. So let's go with 20%. That means that if she is hit 10 times the odds of one or more hits on the turret or barbett is almost 90% even 5 hits results in the probability of one or more turret hits of ~66%. Furthermore from what others have stated it seems to me a penetration wouldn't be required but any hit that causes a signifcant plug or spalling could result in a catastrophic turret event. Until the ammo handling problems are fixed the British battlecruisers are in serious danger.

If someone can give me better numbers for the respective target areas I'll rework the numbers. I've also not considered secondary turrets, barbetts, or magazines.
RobertsonN
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by RobertsonN »

Target angle/total obliquity

I agree that confusion is easy. My understanding is that Nathan Okun considered the cases where the Bismarck was (a) 37 deg forward of the Hood's beam (what I have called 53 deg above) and (b) 17 deg forward of the beam (73 deg above). Offord was quite explicit: the Bismarck was bearing 50 deg from the Hood's bow to stern axis. Thus I thought both Offord's and Okun's analyses are for target angle = 90 deg when the enemy is abeam.
On the other hand, in an earlier post I did say that Nathan Okun calculated the total obliquity of a shell striking the Hood's belt to be (a) 44 deg and (b) 28 deg. These figures undoubtedly are in the other convention and should be (a) 46 deg and (b) 62 deg in the 90 deg means abeam convention. My apologies if this caused confusion.
Anyhow, my conclusion was that what Offord, Okun and you say are all broadly consistent. At 16500 yds the Hood was wise to keep target angle to about 50 deg, not just because of the very small chance 'the cinque in the armor' as Offord called it could be hit but also because the main belt could be penetrated as the enemy became more abeam. That seems implicit in Offord's submission to the Board of Enquiry.
RobertsonN
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by RobertsonN »

Re: Tiger

There is another line drawing on the web (further on in that Wikipedia article) showing the position of all the hits on the Tiger at Jutland. One of them was on a turret, with a hole being blown in the roof. Later on the turret managed to return to action. There is also a picture of a sailor in the turret looking out through the hole.
Tiger was hit 21 times at Jutland, including a 12 in hit on A barbette, an 11 in burst on Q turret and an 11 in burst on X turret.

The Tiger is sometimes given as an example of both how British battlecruisers could absorb a lot of punishment if they did'nt blow up and of how ships of this era could retain some effectiveness after serious damage because they were much simpler than WWII era ships.
lwd
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by lwd »

RobertsonN wrote:Re: Tiger

There is another line drawing on the web (further on in that Wikipedia article) showing the position of all the hits on the Tiger at Jutland. One of them was on a turret, with a hole being blown in the roof. Later on the turret managed to return to action. There is also a picture of a sailor in the turret looking out through the hole.
Tiger was hit 21 times at Jutland, including a 12 in hit on A barbette, an 11 in burst on Q turret and an 11 in burst on X turret.

The Tiger is sometimes given as an example of both how British battlecruisers could absorb a lot of punishment if they did'nt blow up and of how ships of this era could retain some effectiveness after serious damage because they were much simpler than WWII era ships.
Thanks for the info.

I also should have said verticle rather than Horizontal.

The distribution of turret and Bargette hits seems to be in reasonable agreement with my estimates though. Was Tiger the one where the Capatain was more insistent at the antiflash procedures be used at the expense of rate of fire?
RobertsonN
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by RobertsonN »

The number of hits on Tiger varies according to source. But all agree on these three. Parkes says that shell just penetrated X turret and remained lodged between the guns. He also says that the most damaging hit was one between Q and X turrets. This penetrated the 9 in belt and burst inboard, evidently high order. Some splinters penetrated the protection (1 in) deck and one splinter just missed the main steam pipe in an engine room. It also caused a bad cordite fire in the 6 in ammunition and a magazine was accordingly flooded. Many crew killed. This would be one of the few instances in the First War where the thin protective deck was penetrated. The results of this hit could easily have been worse. It was Lion where the greater care was taken with loading arrangements.
In Tiger the thickest deck was the uppermost one, which was 2 in thick over magazines (and therefore around barbettes), 1.5 in over secondary battery and 1 in elsewhere. Lower protective deck was 1 in only (increased to 2 in over magazines after Jutland). Belt was 9 in amidships only, thinning to 5 in abreast A, B and X turrets. There were side screens to the magazines for these, 2.5, 1.5 in and 1 in thick, the thickest where the distance to the side shell was least (i.e. A and X).
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by Byron Angel »

Campbell ("Battlecruisers - Warship Special 1") gives a useful account of the damage suffered by TIGER at Jutland. His description of the three bad hits (9, 10, and 13 by his count) as follows -

quote - - -

9 - Burst on 3.25in front roof plate of Q turret at about 13,500yds. The roof was holed over an area of 3ft 3in x 4ft 8in. Both gun loading cages were jammed but the left one could be used again after removing the cam rail actuating the cordite flash doors, though the right gun remained on secondary loading. The director gear was uninjured, and the guns were laid and trained by director and fired by percussion on hearing the forward guns fire. Three were killed and 5 wounded in the turet, an Q fired only 32 rounds in the battle compared to 109 by B.

10 - Pierced 6in side amour a little below the upper deck and burst 22ft from impact and 8ft from the after 6in hoist. 2-6in charges near the top of the hoist were set on fire bu the flash did not pass down the hoist. Severe damage was done to light structures, whilst the base ofthe shell went through the 1in armour deck adn penetrated the 3/4in thick web of the main steam pipe, andthe armour deck was also holed by another fragment. The after 6in magazine was flooded and due to faults in a ventilation pipe valve and in venting plates Q port magazine andthe after 6in shell room flooded, and water also entered Q shell room.

13 - Hit X barbette at about 13,500yds on 9in armour near junction with 3in armour and 1in upper deck. A piece of 9in armour 27in x 16in was broken off, and the shell entered the turret through the revolving structure about 3ft below the turret shield, but did not explode properly though the filling ignited. The centre training shaft was smashed, one of the flash doors jammed, the left gun depression control valve casting fractured and director laying and firing circuits cut. After 7 minutes the gun began firing again with both guns in director training, individual laying and percussion firing. A total of 75 rounds was fired by X in the battle but some probably went very wide as 2 hours 17 minutes after the hit it was discovered that the turret was 19deg off its correct bearing in director training.

- - - unquote

For what it's worth.

B
alecsandros
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by alecsandros »

delcyros wrote: ... and the CA employed in the production of HMS HOOD´s main side belt was basically of ww1 vintage quality (which is probably a tad bit lower in quality than KC/n.A.).
According to Nathan's research, the FH steel used for the construction of Hood's belt was similar to that used for Nelson class.
Thorsten has provided us with a very nice primary document, which compares the protection offeered by "Nelson armor" (pre-1930s CA)versus "KGV armor" (post-1930 CA).Teh equivalent quality, depending on the thickness of teh material used, is between 85 - 95%, with the thicker plates being closer together in terms of comparative protection.

Thus, the 12" portion of Hood's belt was about 91% of the equivalent quality of KGV armor, which is very close to Krupp post-1930s CA, or 10,927"
RobertsonN
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by RobertsonN »

These numbers for the relative value of Hood/Nelson's armor versus KGV's armor are probably consistent with the immune zones for KGV and Nelson against Tirpitz given in Addendum No. 2 to CB04039 of 1942. Namely, the inclined 14 in belt of Nelson and the 15 in belt of KGV are immune against the German 15 in down to 14000 yds, while the inclined 13 in of Nelson and the 14 in of KGV are immune down to 16000 yds. So in KGV a somewhat thicker belt of better armor make up for the inclination of the belt in Nelson. At this range and aof, though, inclination is of less value than at 10000 yds greater range.
All these numbers are probably optimistic compared with Gkdos 100 data.
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by paul.mercer »

alecsandros wrote:Completely hypothetical scenario:
What if the 1943 equiped Tirpitz would be sent back in time in may 1941 and woudl replace Bismarck.

The main improvements would be: Fumo26 radars, much more AA, better trained and experienced crew, new target tracking systems, giving the ship 360* turning
ability while still mantaining target lock.

What do you think ? Would these improvements be enough for a successfull Rheinubung ? (at least 1 convoy attacked and scattered)
Gentlemen,
This is an interesting question. However, I think to be fair that if Tirpitz is to have all the improvments mentioned above then PoW should have all the improvements fitted to the KGv class later on - including improved gunnery radar and guns that actually worked for more than a few shots at a time.
If one also puts in place the modifications to Hood that never took place then it really would be a terrific battle.
delcyros
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by delcyros »

According to Nathan's research, the FH steel used for the construction of Hood's belt was similar to that used for Nelson class.
Thorsten has provided us with a very nice primary document, which compares the protection offeered by "Nelson armor" (pre-1930s CA)versus "KGV armor" (post-1930 CA).Teh equivalent quality, depending on the thickness of teh material used, is between 85 - 95%, with the thicker plates being closer together in terms of comparative protection.

Thus, the 12" portion of Hood's belt was about 91% of the equivalent quality of KGV armor, which is very close to Krupp post-1930s CA, or 10,927"
I would be very interested to read more about these improvements in CA armour quality. Honestly spoken, I doubt that such a rapid improvement went on unnoticed by the british, who testimonied that rapid progress was made in their face hardened armour quality in the decades before 1910 but little progress appeared in the decade between 1910 and 1920, in which they were merely exploiting their findings.

I can guess about where it comes from. We have little cross country data aviable in this timeframe. The BADEN-trials (not those against the ship but those against some armour plates removed from the ship), evidence from Jutland, some russian AP and on british CA trials, the Ostfriesland trials with pre-1910 german KC against various U.S. Navy APC and the Indean Head trials of 1921 with US and british APC versus various US class A armour.
The HMS HOOD plates were ordered in 1916 and were not different to plates installed in the REVENGE class battleships, in RENOWN and REPULSE as well as in the QE´s and possibly in TIGER, too.
The Indean Head trials suggested that an 11 to 13% advantage exists in striking velocity for british plates over those typical for US manufacturers. Similarely, the BADEN trials show a very drastic inferiority of the KC plates (up to 30%) but this was not substantiated later by the real BADEN trials nor earlier by real penetrations through medium armour (5in to 9in british CA) at Jutland (or else the german L3.2 APC was much more effective in penetration than the Meppen trials or penetration graphs indicate: 0.5 cal at 500m/s and 30 deg obliquity, a possibility for which I don´t see any reason to accept).

Finally, the doc posted by Thoddy doesn´t only give relative figures for NELSON period CA and KGV period CA. It also gives average striking velocities at various conditions for KGV period armour and these need to be put in context with the ww2 trials on german improved KC/n.A. armour plates. It appears that the british trial plates comparatively tested against KC in 1946 were significantly better in resistence than average KGV plates guessing from the numbers of the original document comparing KGV and NELSON armour. It´s probably another case of selective comparison, which is my explenation for the BADEN tests, too. Anyway, german KC/n.A. was about as effective as the best quality 1946 british CA in thicknesses around 520 lbs in proper tests against 15in and slightly superior in resistence to average british CA used in KGV-class battleships. In tests conducted against 14in the british 480lbs trial plates seemed to be superior, but once more, these specially selected plates were also significantly superior to the figures cited for average british CA as of KGV quality.

The bottomline is I don´t think that HOOD´s CA is anything close to improved post 1930 KC/n.A. in terms of stopping power -it used an inferior steel quality, missed a proper temper and had a deeper chill than post 1930 british CA, causing larger scaling effects than ww2 period british CA. The latter was still using the same steel but tempered and had a much thinner chill, which greatly enhanced it´s stopping power against large projectiles. German KC/n.A. deep chill suffered from larger scaling effects but nevertheless was about as good as average british ww2 CA when attacked by major calibre APC owing to it´s superior steel quality and finer grain. Against ww1 period CA this should be quite significant because the temper advantage and the difference in chill depth beeing much less pronounced.
the U.S. Navy postww2 tested CA from Britain and KC/n.A. was found to be of about equal superior quality when attacked by large calibres (14in & 16in) compared to their own ww2 type class A (8.9 to 15% advantage) but only KC/n.A. was slightly better when attacked by 8in compared to US class A (3% advantage for KC as opposed to a roughly 10% disadvantage for CA over US class A).
alecsandros
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by alecsandros »

delcyros wrote:
The bottomline is I don´t think that HOOD´s CA is anything close to improved post 1930 KC/n.A
But who said that ? I only said that Hood's 12" belt was probably equivalent to a 10,97" KC n/A belt.
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by RobertsonN »

On looking at Addendum 2 of 1942 again, what strikes me is that despite the diagrams showing the belts of Nelson and KGV being proof against the German 15 in down to 16000 yds (machinery) and 14000 yds (magazines) with the enemy abeam (target angle 90 deg), it goes on to recommend a target angle of 60 deg (30 deg fore or aft of the beam) because this will allow all guns to bear and it will guard against superpenetration of the German 15 in shells. This probably puts it more in line with Gk dos 100 values.
The fact that the British looked to increase the resistance of the belt by inclining it in the Hood and Nelson would seem more consistent with there not having been an improvement in armour quality from Revenge. On the other hand, the improvement of quality of CA in the 1930s probably eased or even allowed the return to molded vertical belts seen in KGV.
Last edited by RobertsonN on Wed Jul 06, 2011 8:34 am, edited 2 times in total.
alecsandros
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by alecsandros »

RobertsonN wrote:On looking at Addendum 2 of 1942 again, what strikes me is that despite the diagrams showing the belts of Nelson and KGV proof against the German 15 in down to 16000 yds (machinery) and 14000 yds (magazines) with the enemy abeam (target angle 90 deg), it goes on to recommend a target angle of 60 deg (30 deg fore or aft of the beam) because this will allow all guns to bear and it will guard against superpenetration of the German 15 in shells. This probably puts it more in line with Gk dos 100 values.
Yes, I am also very interested in the perspective the major powers had over the enemies weapons during WW2. In this case, the British underestimated the German 15" gun by a very large margin. If we are to use KC n/A as comparable with British post-1930 CA when attacked by German 380mm shells, (which is a little bit of a stretch), the thickest portions of KGV's belt would be vulnerable up to 22.000y and Nelson up to 24.000y, considering 90* target angle.
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Re: late 1943 Tirpitz instead of Bismarck in May 1941

Post by Djoser »

José M. Rico wrote:
"It cannot be truly said that, "Hood was destroyed by a lucky hit". There are numerous magazines in a capital ship in addition to the four large ones which lie beneath the main turrets.
If therefore, a heavy shell penetrates the armour at the angle of descent given by long ranges, the chance of one of the magazines being ignited is quite considerable."

Admiral of the Fleet Lord Chatfield
Of course a second run of the Denmark Strait made have ended up with Hood afloat, but the possibility of blowing up again by an explosion of, let's say, the forward magazines this time, is there too.

A question for all: Would the battlecruisers Queen Mary, Indefatigable, and Invencible blow up again in a second battle of Jutland?
The ammunition handling procedures were surely to blame to a large extent, but again as has been mentioned, the volatility of the cordite charges the British used also played a significant role, as did the under-armoring of these ships.

I have posted elsewhere that the QM at Jutland went in a remarkably similar way to Hood--only it was the forward 4" magazines setting off the main magazines right next door, not the rear 4" magazines.

We can observe a clear-cut propensity to blowing up in the British BCs, what with 4 of them doing so within a very short time of action beginning--and there was also the HMS Vanguard suddenly blowing up while at anchor.
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