British postwar tests on armor

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Herr Nilsson
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Re: British postwar tests on armor

Post by Herr Nilsson » Sat May 04, 2019 10:00 am

The hole in the upper deck was just about 28 cm IIRC. Later on the estimation of the bomb size was corrected. I will try to find it again. Unfortunately I‘m very busy until Wednesday.
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Marc

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Alberto Virtuani
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Re: British postwar tests on armor

Post by Alberto Virtuani » Sat May 04, 2019 9:14 pm

Hello everybody,

in the report on the bombing of Gneisenau dated April 6, 1942 (T1022-3864 PG47996) there is an introductory short summary of what happened. This is the first part of the E paragraph at pag 3. Sorry for the small dimension that is due to the forum image size limit: if you save it you should still be able to read it...

Gneisenau_Bomb_PG47997B.jpg
Gneisenau_Bomb_PG47997B.jpg (58.32 KiB) Viewed 393 times

I have tried (very tiring indeed) to translate it via "google translator" and it gives something like this:
(I have integrated a bit, I hope in the right way (in italic what I couldn't understand anyway)):
Path of the bomb and the following detonation.
The bomb penetrated the upper deck at frame 185 with an impact angle of 70.5 °, the Battdck. at the 185.7 m bulkhead, it was deflected by the aft edge of the armored longitudinal bulkhead at frame 185.7 and detonated on the main armored deck at frame185.5, at the front stb corner breakthrough for the exhaust duct of the powder chamber. The jet of flame created during the detonation brought the cartridges in both powder chambers almost simultaneously to the burner. As an explanation, it is stated that two shipments were made in the ship, the time perhaps 10 Sec. lay apart. The blast wave cemetery in the area Abt. The Battdck. the facilities in the Batt and Zwdck., damaged in the Zwdck and Battdeck the bulkhead 166.2 mainly on Bb side and the bulkhead 185.7 in Battdck. Due to the flood of tower "A", the oil and water mixture got through the damaged ducts, etc. into the Zwdck. There have been formed here Olgase (oil gases???), located in Battdck. About 1/2 hour after hit fired. It is perfectly clear from the destruction in the area of ​​these rooms that explosions of considerable strength must have taken place.
From the above, it's unclear whether the main armored deck was penetrated or even pierced. The ventilation truck (exhaust duct) may have been the way the flash propagated below the MAD but this is unclear as well. No open hatch is mentioned, but may it be that the exhaust duct had an armored hatch/cover that could be closed when the ship was at action stations ? I have no clue.


Also interestingly, this summary is perfectly in line with Whitley account (viewtopic.php?f=1&t=8539&start=30#p83176 or see his book pag.177-178). Whitley must have read this report but he also "added" the open hatch to the 28cm magazine and also "interpreted" that it was the second explosion to ignite the magazines, while here it looks like it was the first one... Was there another, more detailed, report ?


If anybody has this full report (it's a very long one (100 pages) with heavy schemes (viewtopic.php?f=1&t=8539&start=45#p83262) and photos (viewtopic.php?f=1&t=8539&start=45#p83270)) and is able to see whether there are firm conclusions about the possible "penetration" of the Main Armored Deck, regarding the hatch that was subsequently never found (according to Whitley), please let us all know.


Bye, Alberto
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Re: British postwar tests on armor

Post by paul.mercer » Sun May 05, 2019 9:23 am

Gentlemen,
Did any of the 'Tallboys that hit Tirpitz go right through the ship and out of the bottom?

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Re: British postwar tests on armor

Post by dunmunro » Sun May 05, 2019 7:56 pm

paul.mercer wrote:
Sun May 05, 2019 9:23 am
Gentlemen,
Did any of the 'Tallboys that hit Tirpitz go right through the ship and out of the bottom?
The first hit penetrated the bow, and probably burst upon striking the seabed. The resulting damage and shockwave flooded most of the bow section. I'm not sure about the other two probable hits.

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Re: British postwar tests on armor

Post by Dave Saxton » Sun May 05, 2019 10:19 pm

paul.mercer wrote:
Sun May 05, 2019 9:23 am
Gentlemen,
Did any of the 'Tallboys that hit Tirpitz go right through the ship and out of the bottom?
I looked up Brown:

The hit scored on Sept 15 passed through the flare of the bow and out the side before bursting about 15 meters below the bottom of the bows as a gigantic mine.

There were no hits scored on the Oct 29 mission.

On the final mission there were 3 hits scored. The first hit passed through the catapult and detonated as it was penetrating the 80mm panzer deck. The explosion tore a 14 meters hole out the side of the ship amour belt and all. The port number 1 boiler room, the center boiler room, and the port turbine room, were flooded. The second hit just port of turret Bruno and broke up on impact with the panzer deck. Some sources claim it was dud, but I think a dud that remained intact would have passed through, and there is no confirmed evidence of this that I have seen. The third hit abreast the rear port 5.9" turret. It caused flooding of the port number three 5.9" magazine but no magazine explosion. As the ship reached a 70 degree list, C turret magazine partially exploded, blowing turret C out of the barbette.

The bombs used were the medium capacity versions instead of the high capacity versions. The warhead was still 5,100 lbs of Torpex! The 12,000 lb bombs were dropped from 13,000 feet and reached a impact velocity exceeding 345 meters/sec.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: British postwar tests on armor

Post by paul.mercer » Mon May 06, 2019 9:01 am

Gentlemen,
As always, many thanks for your replies.

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Re: British postwar tests on armor

Post by pgollin » Mon May 06, 2019 10:09 am

Alberto Virtuani wrote:
Sat May 04, 2019 9:14 pm
.

If anybody has this full report (it's a very long one (100 pages) with heavy schemes (viewtopic.php?f=1&t=8539&start=45#p83262) and photos (viewtopic.php?f=1&t=8539&start=45#p83270)) and is able to see whether there are firm conclusions about the possible "penetration" of the Main Armored Deck, regarding the hatch that was subsequently never found (according to Whitley), please let us all know.


.
.

I take it that you don't understand irony !

:clap:

.

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Alberto Virtuani
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Re: British postwar tests on armor

Post by Alberto Virtuani » Mon May 06, 2019 11:14 am

I take it that you don't understand. Full stop. :lol:

You should try to post if you have something to say related to the topic, not just to make useless controversy in any thread, only to satisfy your anger, as you have done above...
Last edited by Alberto Virtuani on Mon May 06, 2019 12:48 pm, edited 1 time in total.
"It takes three years to build a ship; it takes three centuries to build a tradition" (Adm.A.B.Cunningham)

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Re: British postwar tests on armor

Post by wadinga » Mon May 06, 2019 12:46 pm

Hello Phil,

Of course Mr Virtuani understands irony
using a big gun to hit a "butterfly"
Tirpitz=butterfly Whaaaatt???

From Wikipedia:
The bomb was aimed at the target during an operation and proved capable of penetrating deep into hardened reinforced concrete when it hit. This, however, was not the primary intention of Barnes Wallis's design. The bomb was designed to make impact close to the target, penetrate the soil or rock beneath or around the target, and then detonate, transferring all of its energy into the structure, or creating a camouflet (cavern or crater) into which the target would fall.
This 'earthquake' effect caused more damage than even a direct hit that penetrated the armour of a target, since even a burst inside a bunker would only damage the immediate surroundings, with the blast dissipating rapidly through the air. An earthquake impact shook the whole target, and caused major structural damage to all parts of it, making repair uneconomic. The attack reports below should be considered with this in mind.
The Tallboy was more ground penetrating than armour piercing. Armour piercing naval shells were converted into bombs for Pearl Harbour. The RAF developed both 1600 and 2000 lb AP bombs.

I read David Brown Tirpitz Floating Fortress as being slightly sceptical about Tallbuoy's armour, not concrete, piercing properties. The RAF had contemplated using either Chastise or Highball bouncing bombs against Tirpitz, which would have depending on mining effect. Of course the X craft also attacked with mines, for mining effect, not limpets, and a number of the FAA attacks were with A/S bombs for near miss mining effects. An earthquake effect, which Tallbuoy was designed to create, under Tirpitz in very shallow water might have broken her back, blown out her unarmoured double bottom, and deranged turret roller paths, machinery mountings and propeller bearings. Blasting a chunk out of the side of the ship from deck to double bottom worked quite well too. Interestingly Brown mentions another bizarre "indirect" weapon, a buoyant bomb supposed to near miss then float up underneath Tirpitz and explode against her bottom.

All the best

wadinga
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Re: British postwar tests on armor

Post by alecsandros » Mon May 06, 2019 12:52 pm

The Lancasters targeted the battleship, not it's surroundings.

The water in the fjord wasn't shallow at all (it isn't today and it wasn't back then either). From memory, Tirpitz skeletal remains are sunk to a depth of 80 meters or more.

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Re: British postwar tests on armor

Post by Alberto Virtuani » Mon May 06, 2019 12:53 pm

Hello everybody,

apart from the sterile provocations (irony...) of some above guys, I still have doubts about what happened to Gneisenau.

Especially, if the bomb was a 2000 lbs, then I may understand the penetration of both armor decks, if the bomb was a "smaller" one (1000 lbs and especially 500 lbs), I find it quite strange and in case it did perforate/punctured the MAD, then Tirpitz (not more protected than Gneisenau) could have easily been sunk using normal small bombs, instead of using the Tallboys... :think:

I hope someone can make clarity over this point regarding the German horizontal protection scheme efficiency against bombs.


Bye, Alberto
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Re: British postwar tests on armor

Post by alecsandros » Mon May 06, 2019 1:04 pm


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Re: British postwar tests on armor

Post by wadinga » Mon May 06, 2019 2:38 pm

Hello Alecsandros,
The water in the fjord wasn't shallow at all (it isn't today and it wasn't back then either). From memory, Tirpitz skeletal remains are sunk to a depth of 80 meters or more.
I should revisit your memory. The mooring site is very shallow, the "Beast" couldn't even capsize properly. See Antonio Bonomi's excellent postings at viewtopic.php?t=436 from 2005. Back in those distant days everything he posted was reliable.

As Antonio Bonomi posted:
They choose the place in order to still use the ship even if sunk, as the water below her was less than a meter and they knew she was going to be hit again and probably sunk, but this was not enough as we know.

From the report:
Calculations indicate that after the evacuation was underway there may have been as much as 17,000 tons of sea water in "Tirpitz", causing a listing moment of about 450,000 foot tons. Normally, the ship would have continued on over. However, a balance was reached at 60 degrees, apparently because the ship' s bottom was resting against firmer soil.
While "Tirpitz” was inclined at 60 degrees, turret “Caesar" suddenly exploded, the whole rotating structure being hurled out of the barbette. The reaction from this explosion upset the balance and the ship capsized.
Waterline L4 from the last diagram in the report, shows she didn't completely sink because she was resting on the soft mud bottom at a 134 degree list.
The diver's investigation of the bottom and port side of "Tirpitz" was halted because of the danger to the diver in penetrating further into the torn shell plating and also because of the short period of daylight.
The investigation revealed considerable information concerning the damage. The lower edge of the port waterline armor projects slightly out of the mud.
Poor little

So, for starters, it would appear you have got mixed up with cargo ship Tirpitz sunk in the Mediterranean in 80 metres of water.

It seems a Milanese Puccini fan may have got tragic heroine Madama Butterfly and the Nazi Death Star II mixed up.

All the best

wadinga
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Re: British postwar tests on armor

Post by alecsandros » Mon May 06, 2019 3:37 pm

Yes, I mis-remembered.
The ship was purposefully surrounded with sand and rocks, in order to avoid her capsizing and sinkage.
The depth of Tromso is another matter, though (see water depths here http://fishing-app.gpsnauticalcharts.co ... 38/19.6391)- and the Lancasters were targetting the battleship, not the anchorage point.

Photos of the breaking site and of the wreckage:

https://www.bismarck-class.dk/tirpitz/m ... d_now.html

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Re: British postwar tests on armor

Post by alecsandros » Mon May 06, 2019 5:19 pm

Alberto Virtuani wrote:
Mon May 06, 2019 12:53 pm

I hope someone can make clarity over this point regarding the German horizontal protection scheme efficiency against bombs.
I re-read some articles on Scharnhorst and Gneisenau's bombings while at Brest,
and counted 9 bombs hitting them (of 500 and 1000lbs varieties). Damage was considerable, yet all 500lbs bombs exploded on (or above) the MAD, while all the 1000lbs bombs (all 3 hit Scharnhorst in the same night) where all duds (several of them perforating all the way to the sea floor).

Altitude of bombing attacks is given as 3000-3700meters (10.000 -12.000 ft, level bombing).

bomb damage Scharnhorst at Brest:
https://www.scharnhorst-class.dk/scharn ... brest.html

sketchy details of bomb damage Gneisenau at Brest:
https://www.kbismarck.com/gneisenau.html

more details are given in Garzke and Dulin's "Axis Battleships"
Last edited by alecsandros on Mon May 06, 2019 5:41 pm, edited 1 time in total.

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