1921 firing trials against Baden

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Tiornu
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Post by Tiornu »

that first shell looks to me to be cpc rather than ap, but i could be wrong. the second looks like the first improved version of late-wwi, which was transitional to the well-known greenboy. the wwii shell was a later type.
marty1
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Post by marty1 »

There both 15" APC.
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Post by marty1 »

The attached image shows Vdrop for 15-inch MkI APC from several sources. Campbell, the Baden Trials & NavWeps all appear to represent about the same family of Vdrop curves. Campbell's data actual comes relatively close to the Baden Trials. He has 1537-fps at 15000-yrds as opposed to 1550-fps at 15500-yrds.

On the other hand the KDOS-100 curve for 15-inch MkI APC looks fairly optimistic as to the MkI being able to hold onto its velocity with range. It looks like the Germans under-estimated the velocity drop for the MkI.

Image
Bill Jurens
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Armor tests

Post by Bill Jurens »

I may be missing something here, but...

The GKdos100 curves etc. represent the penetration of German Projectiles into German armor of roughly WWII vintage, which is -- as one might expect -- all the Germans had to test against. It's not surprising, at least to me, that testing British projectiles against German armor of WWI vintage would give somewhat different results. I'd be surprised if that didn't happen.

Bill Jurens.
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Post by marty1 »

Meanwhile back at the Seydlitz. The range estimate for none-Penetrating 15-inch APC at Jutland was apparently 19,000-yrds. It struck the turret face – armor thickness ~250mm of WWI era KC. Using the Baden & Campbell Vdrop data we can probably expect an impact velocity of about 1400-fps. Descent angles (again from Campbell) probably about 19 or 20-degrees. The face of the of the Seydlitz's turret armor looks to be inclined approximately 20 to 22-degrees. The net compounded angle of impact relative to the turret face inclination is probably about zero.

Image

Based upon the Baden Trials, the 15” APC should have been capable of penetrating about 14.75-inches of WWI era KC at a range of ~19000-yrds and 0-degree Obliquity. This exceeds the Seydlitz’s turret face armor thickness. Yet from Tiornu’s above account this hit should have been very near limit velocity for 15-inch APC vs WWI era German KC. So why didn’t this particular round penetrate? A closer look at the details regarding this particular 15-inch APC hit on the Seydlitz suggests that the bursting charge from this projectile exploded prior to complete penetration. So while the shell just succeeded in barely holing the armor this probably wasn’t on account of the projectile being very near the Seydlitz’s turret face limit velocity vs, 15” MkI APC.

There are several other examples of 15-inch APC hits during Jutland that did not result in penetrations. These may be worth examining and comparing to the Baden Trials.
Last edited by marty1 on Wed Mar 16, 2005 1:52 am, edited 1 time in total.
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Re: Armor tests

Post by marty1 »

Bill Jurens wrote:I may be missing something here, but...

The GKdos100 curves etc. represent the penetration of German Projectiles into German armor of roughly WWII vintage, which is -- as one might expect -- all the Germans had to test against. It's not surprising, at least to me, that testing British projectiles against German armor of WWI vintage would give somewhat different results. I'd be surprised if that didn't happen.

Bill Jurens.
As far as I know no one is questioning that on this thread nor are they asserting that German WWI era KC is Comparable to WWII KC. I'm not sure where that idea arose?

The question is was an improved windscreed added to to British 15-inch MkI APC after WWI? Or can we take for granted that the Germans KDOS estimate of British 15-inch APC greatly underestimates the projectiles velocity drop vs range?
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Post by Tiornu »

"Based upon the Baden Trials, the 15” APC should have been capable of penetrating about 14.75-inches of WWI era KC."
i don't understand how the baden trials can tell us anything about the hit on seydlitz.
the british 15in windscreen was changed when going from the 4crh to the 6crh shell. i don't know about any other windscreen changes, if there were any.
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Post by marty1 »

Tiornu wrote:"Based upon the Baden Trials, the 15” APC should have been capable of penetrating about 14.75-inches of WWI era KC."
i don't understand how the baden trials can tell us anything about the hit on seydlitz.
What dont you understand?

Tiornu wrote:"the british 15in windscreen was changed when going from the 4crh to the 6crh shell. i don't know about any other windscreen changes, if there were any.
This was a change to 15" MkI? Or is the 6crh in reference to a different 15" Mark. Moreover are you refering to the increase in windscreen length between 15" MkXII APC and 15" MKXXII APC? I am asking specifically about MkI.
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Post by Tiornu »

"What dont you understand?"
it looks like you're trying to synthesize results from two pools of data that are not comparable. why would the baden trials illuminate the performace of a different weapon?
i didn't know there was a mk 22. the change to a longer windscreen was between the mk 13a and the mk 17b.
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Post by marty1 »

Tiornu wrote:"What dont you understand?"
it looks like you're trying to synthesize results from two pools of data that are not comparable. why would the baden trials illuminate the performace of a different weapon?
i didn't know there was a mk 22. the change to a longer windscreen was between the mk 13a and the mk 17b.
Not really. I am simply looking at performance of British 15-inch MkI APC vs. WWI German KC, and how it relates to the Krupp Penetration Equation. Actual firing trial data of the period is the most illuminating information I would hope to get on this subject. I'm not trying to ram anything down anyones throat on this. I just think the Baden Test Data that Jose posted is a fun subject to kick around, and hope he will continue to post this sort of material in the future.

Yess --there is a Mk22 with a much longer windscreen than MkXII.
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José M. Rico
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Post by José M. Rico »

Hi Marty,

There is nothing at all in the Baden Report about the exact type of 15-inch APC used during the trials other than the fuze utilized and the filling. That should give us a clue...

… as to why didn't that 15" APC round penetrate Seydlitz's relatively thin 10-inch turret face, I have no idea. According to the data available, one would expect that plate to be easily pierced from 19,000 yards but… Is the range and I.V. you gave, correct? Are you guys sure it was an A.P.C. shell?

In the Baden trials there is one round that hit the 10-inch upper belt and penetrate it right away. I am attaching the info on Round 17:

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

Round 17.

Target: 10-in. belt above boiler room.
Shell: 15 in. A.P.C.
Fuze: 16 D.
Filling: 70/30 Shellite.
S.V.[striking velocity]: 1,550 fps [472 mps].
Delay: 38 ft.
Nature of burst: E.O.
Point of impact: 10 in. belt 3 ft. below upper deck.
Angle of impact from normal: Vertical, 13 deg. 40 min; horizontal, 5 deg. 10 minutes Resultant, 14 deg 40 min.

After piercing the 10 in. belt the shell pierced the outer bunker bulkhead (hole 4 ft. by 2 ft.), the main deck and the inner bunker bulkhead (hole 5 ft. by 1 ft. 6 in.), finally bursting against the funnel casing above the centre boiler of the foremost boiler room.
The armoured gratings over this boiler were unshipped and many fragments of shell entered the boiler.
Two of these entered the steam drum, and the remaining fragments severely damaged the tubes each side.
The nose of the shell weighing about 400 lb. Went through the port electric cable passage (under the main deck, in the centre boiler room) and, after piercing the bulkhead between the two boiler rooms, it was found embedded in the tubes of the port boiler. Most of these tubes were broken.
The transverse bulkhead between the foremost and No. 2 centre boiler rooms was pierced in three places, two of these fragments piercing the outer shell of the centre boiler in No. 2 boiler room. One of these fragments traversed the boiler, making 3 in. holes in the casing each end, but did no further damage. The other fragment entered the outer casing, grazed the steam drum, and removed a 30 in. manhole cover in the after end of the casing without damaging the steam drum or tubes.

Image

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

By the way nice graphics Marty! Do you do that manually or use some kind of special software?

José
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Armor Penetration

Post by Bill Jurens »

Marty wrote:

"The question is was an improved windscreed added to to British 15-inch MkI APC after WWI? Or can we take for granted that the Germans KDOS estimate of British 15-inch APC greatly underestimates the projectiles velocity drop vs range?"

Please don't misinterpret my comments below as being sarcastic or due to impatience. Sadly, I still seem to be missing something here...

I simply cannot understand how information taken from a German document showing the results of German projectiles impacting German armor in the 1930s, could be used to determine anything with regard to British tests of British projectiles impacting German armor in 1920 or so. This would seem to be comparing apples and oranges, certainly for projectiles and probably for armor. I can't for the life of me see how Kdos 100 ( the commonly circulated versions of which were perloined from my original copy by the way, without my knowledge or permission ) could possibly have to say about any of the Baden tests.

To answer the questions:

1) The British did indeed adopt a more streamlined windscreen for most bullets between the wars, which -- as might be expected -- increased the striking velocities somewhat. Just about everybody did. All of this is in the range tables, or can (with some skill) be re-computed. The nominal striking velocity for a given British projectile at a given range is really not in any doubt at all, or certainly need not be.

2) KDOS100 says nothing at all about British projectiles of any type. It just gives curves of penetration velocity vs angle of impact and plate thickness. The German curves are generic, representing the performance of their own projectiles, not British ones.

Bill Jurens
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Post by marty1 »

Bill Jurens wrote: I simply cannot understand how information taken from a German document showing the results of German projectiles impacting German armor in the 1930s, could be used to determine anything with regard to British tests of British projectiles impacting German armor in 1920 or so. This would seem to be comparing apples and oranges, certainly for projectiles and probably for armor. I can't for the life of me see how Kdos 100 ( the commonly circulated versions of which were perloined from my original copy by the way, without my knowledge or permission ) could possibly have to say about any of the Baden tests.
Hi Bill:

My Understanding from Jose -- and he can correct if I'm wrong -- is that the two KDOS Figures he posted earlier on this thread were for British 15-inch APC. "38.1cm gun of the British Queen Elizabeth, the 15" Mark I". See the thread on this forum entitled: "Questions About 38,1-cm Psgr.zu", November 14, 2004.

We are not comparing KDOS penetration values with those of the Baden Trials. There are two separate lines of discussion going on. I am mostly interested in performance of 15" MkI APC vs. German WWI KC armor. That's why I am interested in the Baden Trials and subsequently segued into Jutland. I am looking for additional cases of 15-inch MkI APC failures vs. German WWI KC Armor.

My discussion regarding the KDOS figures was simply to show how I guess N.Okun back calculated the Krupp Constant for 15-inch APC vs. WWII era KC n/a. But there are two different Krupp Constants for the Krupp Equation being discussed on this thread. One for MkI APC vs. German WWII KC n/a -- one for determining MkI APC vs. German WWI KC. However since my previous questions to this forum regarding the Krupp Equation have fallen on deaf ears I assumed the expertise was not here. So I'll run with what I have back calculated myself based upon actual firing trial data -- unless of course you have access to real Krupp Constants -- in which case I would love to hear what you have to say on the subject.

The only real cross pollination that is occurring on this thread is the velocity decay data. Moreover the figure that Jose posted (photos/69.jpg) is a much less aggressive velocity drop than what is typically referenced for 15" MkI APC. I see only two possibilities with this:

1) The Germans underestimated the Vdrop for MkI
2) The British added a fair bit to the nose length of their wind-screen on 15-inch MkI APC. This would have had to have occurred sometime after the Baden Trials as the trial data indicates a velocity of ~1550-fps at 15500-yrds. So the Baden Trial Vdrop matches up reasonably well with commonly referenced Vdrop for this projectile. In my mind this was the proper Vdrop data to use for any Jutland data I wished to examine.

I do have one question for you. You mentioned the velocity data for 15-inch APC MkI is not in doubt. Fair enough. I don’t have firing\range tables for this particular projectile. I only have the J.Campbell Data and the Baden Trials data. As far as recreating this data in the absence of actual range tables, what would you choose for a drag function? In addition what would you choose for a form factor? Personally I’d run with a simple G1 (or KD1 depending upon what part of the world your from) and based upon the nose length I’d guess the form factor to about ~0.75. What would be your inclinations regarding the appropriate drag function and form factor for this projectile? No cheating now :D – pretend you don’t have access to any range table data.
Last edited by marty1 on Wed Mar 16, 2005 6:59 am, edited 1 time in total.
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Post by marty1 »

José M. Rico wrote:Hi Marty,

There is nothing at all in the Baden Report about the exact type of 15-inch APC used during the trials other than the fuze utilized and the filling. That should give us a clue...

… as to why didn't that 15" APC round penetrate Seydlitz's relatively thin 10-inch turret face, I have no idea. According to the data available, one would expect that plate to be easily pierced from 19,000 yards but… Is the range and I.V. you gave, correct? Are you guys sure it was an A.P.C. shell?

In the Baden trials there is one round that hit the 10-inch upper belt and penetrate it right away. I am attaching the info on Round 17:

By the way nice graphics Marty! Do you do that manually or use some kind of special software?

José
Hi José:

Thanks for posting the results of rnd 17 as well as the additional figure. Regarding the Seydlitz non-perforating hit, the information is derived from John Campbell's excellent book "Jutland, An Analysis of the Fighting". If you don't already have the book, you should get a copy.

The 15-inch hit at 17:10 on the Seydlitz Turret Face is described by Campbell as having occurred from a range of about 19,000-yrds. He also indicates that the Valiant was engaging the Seydlitz during this time frame. While Campbell is not explicit about the hit being either 15-inch APC or 15-inch CPC he does give an ammunition expenditure tally for many of the Battleships and Battle Cruisers involved at Jutland. Valiant apparently fired off 278 APC and only 10 CPC during the course of the battle. The probability is that the Seydltiz turret hit was from 15" APC, but of course the text by Campbell is not definitive on this particular matter. Personally I think it was 15-inch APC hit in which the base charge prematurely detonated.

But since 15-inch CPC has been brought up, were there additional 15" CPC trials within the Baden Test Report? It might be interesting to kick this around a bit for giggles. Was Round-10 the only CPC shoot during the trials?

As to the graphics question -- it's pretty sloppy I will admit -- but it's the best I can do with the software I have. :D
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Post by Tiornu »

"I am simply looking at performance of British 15-inch MkI APC vs. WWI German KC, and how it relates to the Krupp Penetration Equation."
yes, and that's why the baden trials won't help you. no mk 1 shells were used, to the best of my knowledge. chances are that the full-sized shells were greenboys, which were standard until 1923 when replaced by the mk 5. (the trials were conducted in feb 1921.) a lightweight ap shell was also used, 1520 lbs.
forgetting the various marks for a moment, the shell body and cap differences could be completely irrelevant. it may be (i cannot say) that the only reason the shell failed to pierce seydlitz's armor is because it exploded too soon to do so. this could be because of the fuze action or because the filler was (i believe) pure lyddite. i don't know of any system to predict when a filler will self-initiate.
José, can you post the illustration for round 16? that's the one that i think gives a frightening depiction of what a modern ap shell can do. it knocks out a plug of casemate armor that shoots across the entire width of the ship, right through both splinter bulkheads, and that's in addition to the damage caused by the shell itself.
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