Bismarck/Tirpitz = most powerfull European battleships

[Karl Heidenreich]

After viewing Thorsten's links I wonder how on Earth is somebody going to base his calculations with the navweaps and it's supporters material... it's clearly unaccurate.

[Dave Saxton]

The constant for Wh @ up to 80kg/mm2 vs 38cm and larger projectiles is 660. The constant for deck 2 for Wh @ 90kg/mm2 is 720, IIRC. Anyway the product squared is ~1.2 The coefficient representing the thickness ratio from the chart is .89 =107%

Result is ~140mm over machinery
Result is ~160mm -195mm over magazines.

One would have to also take into account the impact angle on the scarps for the wing tanks protection.

[JtD]

Formula 6a, page 78, which the table on page 98 is based on:

(C2/C1)^2 = 1.2, as you say
e = 80/130 = 0.615

Therefore

V2/V1 = sqrt((1-0.615)^1.6 + 1.2 * 0.615^1.6) = sqrt (0.22 + 0.55) = 0.88

Not 1.07. Point out mistakes if you wish.

[Dave Saxton]

0.615 is the ratio but it's not the coefficient you multiply the product by. If it is .88, then 1.2 x .88 is ~1.07

[phil gollin]

[A] - .......... the USN empirical formula is as smashed up as a formula can get in a forum. It's just a quick reference and provides good averages for certain shells and ranges. ..............

- .......... There are even formulas simulating the loss of mv/shot...

Ignoring, again, the insults ;

Re. [A] - it only provides "good" averages for USN shells and armour.

Re. - You don't need a formula for loss of muzzle velocity per shot, that is a given value provided with the gun range tables. What might be useful is the actual erosion values measured at any particular time (some RN ones are available in the "gun logs".

------------------------

In addition, discussions also seem to forget the fact that ships, in general, are moving in a seaway, changing the angles from the theoretical.

And, both projectile penetration and armour resistance are matters of statistics and quality control. The accuracies of armour penetration often, not always, quoted in these sorts of discussions end up quoting figres which are mere flights of fancy.

.

[Dave Saxton]

Formula 6a, page 78, which the table on page 98 is based on:

(C2/C1)^2 = 1.2, as you say
e = 80/130 = 0.615

Therefore

V2/V1 = sqrt((1-0.615)^1.6 + 1.2 * 0.615^1.6) = sqrt (0.22 + 0.55) = 0.88

Not 1.07. Point out mistakes if you wish.

I realize now that we are not on the same page. If you follow Gercke's disccussion to the next page, he gives the correct formula for calculating the effective thickness of a two plate system. He gives:

(C1/C2) squared multiplied by e, or the coefficient representing the thickness ratio taken from the table.

If the product is 1 or greater the system provides effective thickness matching or exceeding the sum thickness. The proceeding page deals with calculating the value of e.

This simple formula works. I have applied it to the post war British testing of spaced armour and the formulas predictions match the results.

[JtD]

This is not what he says on the next page. Next page says:

If the coefficient (I gave) multiplied with the ratio C1h/C is larger than one, then the velocity is larger for two plates then it would be for one plate.

Please note, it is C1h and C, not C2. And it's not squared. C1h is the C value for the first plate and C is the C value for a single plate. Please note the line on page 78: "Since C1h = C is a good approximation..." and reduces the formula to what I wrote above. It would be different if the thinner plates had a considerably higher quality than the single plate, but this is not the case.

You're multiplying the wrong values. The C1/C2 has been accounted for in the value you take from the table.

Eventually what he's saying is that a single plate is always better, the best protection being offered by a single plate of the highest quality (rightmost column in the table).

Please also not that this is a shell velocity ratio and not the effective thickness of the armour.

As to matching British test results - where did you get the C values for the British tests from?

[alecsandros]

Says who. And more importantly, why?

Says ADM213/915.
The purpose of the space array tests was to determine the most effective arrangement and properties of the armor deck system. Tests showed that the best results come when the second deck is harder than the one above, consequently having a higher ballistic coefficient.
The ratio between C2 and C1 was ~ 1.07, coming from C2 ~ 705 and C1 ~ 660.

Okay, so 0.8% of the ships vitals were protected by the inclined part of the turtle deck against fire that also hit the upper deck at 25° angle.

2 factual errors in the same proposition. 0.8% ? and "25* angle".
If you care so much about this discussion, the least you can do is get a plan o Bismarck in front of you and only post anything AFTER you see the armor arrangement.

The quote you brought for the upper deck armour contradicts the original building plan. 50mm is what is in the original document says, 80mm is what some website claims without giving a source. You decide.

You show a typical lack of respect for primary German documents and the people who worked months or years for translating them and posting them online FOR FREE.
The quote is from Jose's site, and the sources he used are the most up to date as you can find.
If you don't understand the scope, shape, area and function of the turtle deck, how can you bring into question the "original building plan", which you seem to not have any idea about?
(and if you would take the time and read carefully the quote I posted, you will observe that it depicts the upper deck as having thicknesses of 50 and 80mm, so I don't know what your problem is anyway)

Okay, so when you say that Richelieu's deck was penetrated because of the poor quality of the armour which was not made up for by greater thickness, you don't mean that Bismarck's deck would not be penetrated when hit in the same way.

You are mixing my posts with your ideas. What I said was just that - that Richelieu's armor decks might have been of poorer quality than if they would have been made from STS or Whotan. Period.

4 guns out of 8 are fired. Means each gun fires every second salvo. So it fires every 36 seconds. Not what you meant? Please be as clear as Bgile was in the meantime.

You seem to have the same reading comprehension problem Phil Gollin has. Again, take a few minutes and re-read my and Bgile's post, and you'll see that:
1) they prove the same thing, that Bismarck's artillery could fire at 18 sec intervals
2) you did not understand neither mine, nor "Bgile clear post".

[JtD]

Says ADM213/915.
The purpose of the space array tests was to determine the most effective arrangement and properties of the armor deck system. Tests showed that the best results come when the second deck is harder than the one above, consequently having a higher ballistic coefficient.
The ratio between C2 and C1 was ~ 1.07, coming from C2 ~ 705 and C1 ~ 660.

No, that's not what it says. But I think I prefer discussing that with Dave Saxton, conversation is much more mature with him.

2 factual errors in the same proposition. 0.8% ? and "25* angle".
If you care so much about this discussion, the least you can do is get a plan o Bismarck in front of you and only post anything AFTER you see the armor arrangement.

Okay, so you didn't understand what I wrote. But, considering your tone, I won't clarify since you didn't ask for it.

You show a typical lack of respect for primary German documents and the people who worked months or years for translating them and posting them online FOR FREE.

How can the preference of a primary German document over some data on a website be interpreted as lack of respect for primary German documents?

The quote is from Jose's site, and the sources he used are the most up to date as you can find.

Great, so maybe he can show the original German documents that specify 80mm of upper deck armour in the vicinity of the main batteries.

You are mixing my posts with your ideas. What I said was just that - that Richelieu's armor decks might have been of poorer quality than if they would have been made from STS or Whotan. Period.

Ok. And I said the poorer quality of French deck armour was compensated through greater thickness. Highest single deck thickness after Yamato.

You seem to have the same reading comprehension problem Phil Gollin has. Again, take a few minutes and re-read my and Bgile's post, and you'll see that:
1) they prove the same thing, that Bismarck's artillery could fire at 18 sec intervals
2) you did not understand neither mine, nor "Bgile clear post".

I didn't get your post. I very well understood Bgiles, because he actually managed to say what he meant.

[Herr Nilsson]

The quote you brought for the upper deck armour contradicts the original building plan. 50mm is what is in the original document says, 80mm is what some website claims without giving a source. You decide.

You show a typical lack of respect for primary German documents and the people who worked months or years for translating them and posting them online FOR FREE.
The quote is from Jose's site, and the sources he used are the most up to date as you can find.
If you don't understand the scope, shape, area and function of the turtle deck, how can you bring into question the "original building plan", which you seem to not have any idea about?
(and if you would take the time and read carefully the quote I posted, you will observe that it depicts the upper deck as having thicknesses of 50 and 80mm, so I don't know what your problem is anyway)

There is no primary source which indicates that the upper deck was 80 mm except the small areas around the 4 after secondary turrets.

In case of Bismarck the armour deck was probably 95 mm around turret Anton and Bruno (Tirpitz 100 mm) and 100 mm around Caesar and Dora.
The sloped part near the main armament was 120 mm.
The lower belt of Tirpitz was 320 mm not 315 mm.

[alecsandros]

There is no primary source which indicates that the upper deck was 80 mm except the small areas around the 4 after secondary turrets.

Who said anything else... ?

[Herr Nilsson]

If you're saying the upper deck was 50 mm over the magazines, everything is fine

[Dave Saxton]

The necessary velocity required to penetrate a single plate or a combinations of plates is equated with effective thickness. Note that he is talking about two plates systems. One constant, what ever you want to call it, is for the main plate within the two plate system and the other is for the second plate. It's straight forward enough. What he says is that it is possible for two plate systems to match or exceed the performance of a single plate, by meeting certain specifications of design. Indeed this is true. There are numeruos examples of two plate systems matching or exceeding the performance of a single plate of the same sum thickness. That a two plate system cannot match the performance of a single plate as a rule of thumb is simply not true. Furthermore, we find the required specification of design being utilized by the Tirpitz's two plate system.

[JtD]

For your entertainment and education I've put Gerckes formula into an Excel sheet, which you can find here:

http://www.mitglied.lycos.de/jaytdee/Compoundarmour.xls

If you have any further question, feel free to ask.

[JtD]

As there are apparently no questions left, could one of you please explain to me how you arrived at the figure of C2 ~ 705...720 for Wotan hart?