1921 firing trials against Baden

Guns, torpedoes, mines, bombs, missiles, ammunition, fire control, radars, and electronic warfare.
User avatar
José M. Rico
Administrator
Posts: 815
Joined: Sat Oct 16, 2004 10:23 am
Location: Madrid, Spain
Contact:

1921 firing trials against Baden

Postby José M. Rico » Fri Mar 11, 2005 10:02 pm

Hello,

The following data is from a report part of ADM 186/251. The original report is a bit extensive, so I am only including a brief summary and the results of the four rounds that were fired against 13 ¾ in. [350mm] thick WWI German KC plates:

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

H.M.S. “EXCELLENT’S” REPORT ON “BADEN” FIRING.

On 2 February 1921, firing trials were carried out against the ex-German battleship “Baden”, to the eastward of the Horse Tail Bank. The firing ship was the H.M.S. “Terror” [Monitor of the Erebus class], who was moored 500 yards from the target.
The ship was heeled to 11 deg. towards the firing ship, this angle varying about 2 deg. either way due to the roll; also the ship grounded at low water which reduced the heel about 1 deg. during that period. The amount of heel was produced by removing coal and armour plates on the port side of the ship and by flooding wing compartments on the starboard side. All oil fuel and bilge oil had previously been removed to reduce the chances of fire. This angle of heel kept the top of the 10 in. belt about 3 ft. above water amidships; and the trim of the ship had been previously adjusted by removing the revolving weight of “A” turret.
The gun used for the trial was the 15 in. B.L. Mark I, being the left gun in turret of H.M.S. “Terror.” The charges were adjusted to give a S.V. [striking velocity] of 1,550 fps. [472 mps] corresponding to an angle of descent of 13 ¾ deg. These were:

Charge: 172 lb. 4 oz. M.D. 16
Pressure in tons: 9ּ14
S.V.: 1,550 fps [472 mps]
Range corresponding to S.V.: 15,500 [yards] = 14,173 meters.

Detailed results of selected rounds:

Round 9.

Target: Barbette armour of “X” turret.
Shell: 15 in. A.P.C.
Fuze: 16 D.
Filling: 70/30 Shellite.
S.V.[striking velocity]: 1.550 fps [472 mps].
Delay: 3 ft.
Nature of burst: E.O.
Point of impact: 3 ft. 9 in. from top edge of fixed armour and 25 ft. 9 in. from midship line forward.
Angle of impact from normal: Vertical, 11 deg.; horizontal, 0 deg. Resultant from normal, 11 deg.

The [13 ¾ in.] armour was completely penetrated, a hole 17 in. diameter being made in it.
Apparently the shell burst when it was two-thirds of its way through the armour and the nose of the shell as far as the shoulder was found inside barbette 23 ft. from outer edge of entry hole.
Considerable damage was done to the roller path.
Some damage was caused to machinery in the pocket between girders where the nose of the shell was found.

Round 10.

Target: Barbette armour of “B” turret.
Shell: 15 in. C.P.C.
Fuze: 15 N.D.
Filling: Powder.
S.V.: 1.550 fps [472 mps].
Delay: On impact.
Nature of burst: -
Point of impact: 5 ft. 3 in. above forecastle deck and 23 ft. 4 in. from midship line forward.
Angle of impact from normal: Vertical, 11 deg.; horizontal, 5 deg. 20 min. Resultant, 12 deg. 10 min.

The shell burst on impact [failed to penetrate] with the plate, penetrating 1 ½ in. over a diameter of 9 ½.
The angle connecting the upper deck to the armour was torn away and flattened for 7 ft.
The forecastle deck was bulged downwards for 9 in. and a hole 6 in. by 4 in. was made in this. A large piece of the base was found on the upper deck under the burst.
The thin liners between the plates were loosened and partly squeezed out.

Round 14.

Target: Front plate of “B” turret.
Shell: 15 in. A.P.C.
Fuze: 16 D.
Filling: 70/30 Shellite.
S.V.: 1.550 fps [472 mps].
Delay: Blind.
Nature of burst: Blind.
Point of impact: Front plate of turret midway between the guns.
Angle of impact: Vertical, 12 deg.; horizontal, 11 deg. Resultant, 18 deg. 40 min.

Shell completely perforated armour, making holes of 18 in. in diameter flaked off to 36 in. by 48 in. outside and 24 in. by 36 in. inside.
Shell was found inside turret with nose resting against left girder of right gun-slide.
The center position sight and apparatus in its immediate vicinity was wrecked.
The shell was eventually exploded by a gun-cotton charge with the following result.
The sound of the burst was indistinguishable from that of the gun-cotton detonating, and degree of rapidity of burst was therefore difficult to estimate. Thick black smoke was emitted from all holes in the gun-house.
The left rammer (main cage to transport wagon) was unshipped and damaged.
The nose of the shell and a large part of the body were found lying on a platform 2 ft. below the burst, and two large fragments were lying where the shell had been. Part of the base weighting 30 lb. went through the main cage trunk and was found lying in the gun-house just near of this trunk. Other fragments were found lying about the gun-house and working chamber, but no other serious damage could be found.

Image
Round 14. Shell intact through 13 ¾ in. [350mm] armour at 19 deg. to normal, S.V. 1,550 fps [472 mps].

Round 15.

Target: Thickest part of conning tower (13 ¾ in.) [350mm].
Shell: 15 in. A.P.C.
Fuze: 16 D.
Filling: 70/30 Shellite.
S.V.: 1.550 fps [472 mps].
Delay: On impact.
Nature of burst: P.D.
Point of impact: A 1 in. angle iron round the conning tower 6 ft. from top of tower and 9 ft. 6 in. from center line forward.
Angle of impact from normal: Vertical, 18 deg.; horizontal, 25 deg. 50 min. Resultant from normal, 30 deg. 10 min.

The shell burst on impact [failed to penetrate], making a bulge 4 ft. 6 in. by 2 ft. 6 in. and 4 in. deep, and opening out the plates half an inch at a join.
The inner side of the plate attacked was badly flaked and cracked, two cracks 6 in. deep and 8 ft. 10 in. long being made. No loosening of plates or of securing bolts was made inside the conning tower, but outside the join of the plate attacked was opened from 1/8 in. at bottom to 7/8 in. at top of conning tower. This was 3 ft. from point of impact. The plate attacked was driven in 1 ½ in. from the plate immediately below it, the join being 2 ft. below point of impact.
The starboard door was blown off, the upper hinge bracket being broken.
The deck round the tower under the point of impact was blown away for 6 ft. 6 in. by 3 ft. 6 in. and a storeroom underneath was demolished.
The deck over the Admiral’s cabin was holed and several pieces of shell were recovered from this cabin.
The diameter of the bulge inside the conning tower was 5 ft. and superficial star cracks were made on the bulge.
The damage to fittings inside the conning tower was very slight.

Summary of Rounds. (Barbettes, turret front plate, and conning tower, 13 ¾ in. [350mm] thick.)

Image

This trial shows that A.P.C. will penetrate 13 ¾ in. [350mm] plate where C.P.C. will fail. Round 15 was fired at an angle of 60 deg. which serves to determine by comparison with round 14 the angle of impact at which perforation of 13 ¾ in. armour may be expected.
The performance of A.P.C. shell as regards penetration would appear to be satisfactory.
The insignificant damage caused by round 15 to instruments inside the conning tower, which were mounted on plates built up from the deck and not in contact with the side of the tower, shows that this method of fitting instruments is entirely justified.
Round 9. The German system of connecting the roller path support to the barbette armour was shown to be unsound.
Round 15. An armoured door is a danger unless its hinges are very strong and it is very securely fastened.

Image

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

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Sun Mar 13, 2005 4:19 am

Great Information.

I am trying to get a feel for dimensions involved with shot No14. I realize I am trying to measure along an arc, and the angle of the photo adds a bit of extra skew as well. My best guess is that shot No.14 penetrates the Badens "B" Turret about 18" to 20" from the edge of the left gun port. Does that look about right?

Does anyone know what centerline distance between the two gun ports might be?

Image

I suppose most folks here at familiar with the following web page:

http://www.navweaps.com/

There are Penetration figures given for British 15-inch Mk-I APC. The figures are for 90-degrees impact (0-deg NATO).

Range (yrds)-------Velocity (fps)-----------Penetration (inches)
8629----------------1853--------------------------16
14853---------------1537--------------------------12
19707---------------1329--------------------------11
23734---------------1178---------------------------9

The original reference implies the above represents "side armor" penetration. I assume this implies first generation K.C. Armor(?)

Using the above numbers as a basis for back calculating the empirical constant for the Krupp All-Purpose Penetration Equation I calculate:

C ~ 880 to 920.

This seems very high, but than I suppose these are WWI era APC projectiles vs WWI K.C. armour.

The trials against the Baden are at a simulated range of 15000-yrds. Moreover the charge is reduced such that striking velocities are about 1550-fps. If we assume that the penetration data from the NavWeapons web page is correct, the British 15-inch MkI APC should only be capable of penetrating about 12.1-inches of K.C. @ 0-degrees @ 15000-yrds.

The 15-inch APC penetration for the Baden trials should typically be less than the above 12.1" figure as the impact angles are occuring at about 11 to 30-degrees. Yet at 11-degrees and 18-degrees the 15-inch APC is penetrating about 13.75-inches of armor.

Hmmm...

User avatar
Ulrich Rudofsky
Contributor & Translator
Posts: 844
Joined: Sat Oct 16, 2004 9:16 pm
Location: State of New York

Postby Ulrich Rudofsky » Sun Mar 13, 2005 1:29 pm

The appendix of H. Evers "Kriegsschiffbau" 1943 (1st ed. 1931) contains detailed 1:500 plans of the SMS Bayern. Although there may be printing and paper distortions etc., the distance would come to about ~2.4 meters which matches your lower number of 98 inches (~2.5 m) fairly well.

PS: My 4.8 mm direct measurement on the plan should be rounded off to 5 mm, i.e., 2.5 m. Also the scale bar is not exactly 10 cm on the print, but 9.8 cm.
Last edited by Ulrich Rudofsky on Sun Mar 13, 2005 3:34 pm, edited 2 times in total.
Ulrich

User avatar
José M. Rico
Administrator
Posts: 815
Joined: Sat Oct 16, 2004 10:23 am
Location: Madrid, Spain
Contact:

Postby José M. Rico » Sun Mar 13, 2005 2:41 pm

Hello Marty,

It is indeed an interesting report. The Baden trials demonstrate that a 15-inch Mk-I APC would penetrate 350mm of WWI KC armor when hit at less than 20 degrees from 15,500 yards (1,550 fps). The penetration figures you gave from navweaps.com are most likely approximate with a considerable margin of error, but the result of the firing trial is a fact.

It would have been interesting to perform a similar firing trial against 350mm of WWII KC n/A armor such as that employed on the turret faces of the Scharnhorst and Bismarck Class battleships. The conning tower of Scharnhorst/Bismarck had the same thickness than that of Baden too, although made of the newer KC armor of course.

The complete Baden report includes a total of 17 rounds against plates of different thickness. Of the five rounds that hit the 4-inch roofs of Baden turrets, all except one failed to penetrate. However, that was no surprise at all considering the 15,500 yard range and the small angles of impact.

José

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Sun Mar 13, 2005 3:58 pm

Ulrich Rudofsky wrote:The appendix of H. Evers "Kriegsschiffbau" 1943 (1st ed. 1931) contains detailed 1:500 plans of the SMS Bayern. Although there may be printing and paper distortions etc., the distance would come to about ~2.4 meters which matches your lower number of 98 inches (~2.5 m) fairly well.

PS: My 4.8 mm direct measurement on the plan should be rounded off to 5 mm, i.e., 2.5 m. Also the scale bar is not exactly 10 cm on the print, but 9.8 cm.


Thanks again for you help Ulrich. I am surprised my measurments came out that close. I am usually happy if I can get within about 10% when scaling off of photos.

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Sun Mar 13, 2005 5:19 pm

José M. Rico wrote:Hello Marty,

It is indeed an interesting report. The Baden trials demonstrate that a 15-inch Mk-I APC would penetrate 350mm of WWI KC armor when hit at less than 20 degrees from 15,500 yards (1,550 fps). The penetration figures you gave from navweaps.com are most likely approximate with a considerable margin of error, but the result of the firing trial is a fact.

It would have been interesting to perform a similar firing trial against 350mm of WWII KC n/A armor such as that employed on the turret faces of the Scharnhorst and Bismarck Class battleships. The conning tower of Scharnhorst/Bismarck had the same thickness than that of Baden too, although made of the newer KC armor of course.

The complete Baden report includes a total of 17 rounds against plates of different thickness. Of the five rounds that hit the 4-inch roofs of Baden turrets, all except one failed to penetrate. However, that was no surprise at all considering the 15,500 yard range and the small angles of impact.

José


Hi José:

I agree with your assessment. I think the NavWeaps penetration data is suspect. The extremely high empirical constant required to get the Krupp All-Purpose Equation to work with the NavWeps Penetration Data was the first tip off.

Using the Baden Test Data for shots 9, 14, and 15 it is possible to get a better estimate of the Krupp Constant. Shots 9 and 14 are Complete Penetrations (CP) and Shot 15 is an incomplete penetration (IP). The respective angles of attack for 9, 14 and 15 are 11-deg, 18-deg, and 30-deg. So we can deduce that the limit obliquity occurs somewhere between ~20-degrees and 30-degrees. By the description of shot 14 it appears that 15-inch APC had very little trouble penetrating the 13.75-inches of Turret armor @ 18-degrees. So we can probably narrow the limiting obliquity to perhaps 25-degrees to 30-degrees.

Again using slope effects for US 90mm M82 APC vs. FH armor the slope effects for t/d = 0.916 (Note the 15-inch APC vs. 13.75" KC is t/d = 0.916) we get the following:

Obliquity------------------Slope Effect
0-----------------------------1.000
10---------------------------0.938
20---------------------------0.892
30---------------------------0.800
Interpolating
11(shot 9)---------------- ~0.932
18 (shot 14)-------------- ~0.898

So we know the limiting case from the Baden Trials falls between about 25-degrees and 30-degrees for 15-inch MkI vs. 13.75-inch of WWI era German K.C. Using the above slope effects combined with the results of the Baden Trials allows a back calculation of the Krupp Constant for 15-inch MkI APC vs. German WWI Era K.C. Armor. This turns out to be about 700 to 720. This range for a Krupp Constant appears to be much more reasonable than the 880 to 920 I derived when using the NavWeps Data.

Using the Baden Test Data, and assuming an average Krupp Constant of say 710 the NavWeps data should probably look something more like:

15-inch MkI APC vs. German WWI Era KC
Range (yards)------Obliquity(deg)-------Impact Velocity (fps)-------Penetration of German KC (inches)
----8629---------------------0-------------------------1853----------------------------------------20.9
---14853--------------------0--------------------------1537---------------------------------------16.5
---19707--------------------0--------------------------1329---------------------------------------13.8
----23734-------------------0--------------------------1178---------------------------------------11.9
Last edited by marty1 on Sun Mar 13, 2005 6:09 pm, edited 1 time in total.

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Sun Mar 13, 2005 5:32 pm

Are there any additional limiting cases anyone can think of? Perhaps documented cases of 15-inch MkI APC failing to penetrate any German Ships during Jutland? Ranges and hit locations and possible impact angles in which 15-inch APC did not penetrate.

Tiornu
Supporter
Posts: 1222
Joined: Mon Oct 25, 2004 6:13 am
Location: Ex Utero

Postby Tiornu » Sun Mar 13, 2005 8:46 pm

As i recall there was a 15in hit to seydlitz's turret face which must have been right at the brink between success and failure, as the shell was rejected but a large plug was sent into the gunhouse.
however, this is of no use here. i think we're trying to mix and match numbers from different sources when they are not in the least comparable. the specific grade of armor could very easily change the penetration figures by 10%, maybe more. more importantly, the shell design will make a dramatic difference. that's why jutland can't help us at all. those shells would give miserable performance especially as obliquity increased past 15 degrees.

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Mon Mar 14, 2005 2:36 am

Tiornu wrote:As i recall there was a 15in hit to seydlitz's turret face which must have been right at the brink between success and failure, as the shell was rejected but a large plug was sent into the gunhouse.


Any idea what the range and obliquity of this hit was?

My Janes indicates the turret armor on the Seydlitz turret was 8-inches of KC. Does this sound right to everyone?

Sounds like from your description the hit was probably below the perforation limit velocity, but probably hovering very close to penetration limit velocity.

Tiornu
Supporter
Posts: 1222
Joined: Mon Oct 25, 2004 6:13 am
Location: Ex Utero

Postby Tiornu » Mon Mar 14, 2005 4:01 am

the seydlitz's turret face was 250mm. i'm guessing the shell was ap rather than cpc.

User avatar
José M. Rico
Administrator
Posts: 815
Joined: Sat Oct 16, 2004 10:23 am
Location: Madrid, Spain
Contact:

Postby José M. Rico » Mon Mar 14, 2005 7:41 pm

Hello again,

I am attaching the 15" Mk I penetration curves from "Awa A IA 100/40 g.Kdos Unterlagen mad Richtlinien zur Beslimmung der Hauptkampfentfernung und der Geschosswahl". See links:

http://www.kbismarck.org/photos/69.jpg

http://www.kbismarck.org/photos/70.jpg

According to these curves, and I hope I read them well (correct me if I am wrong), for a striking velocity of 1,550 fps (472 mps) and an angle of about 11º, the side armor penetration equals to more than 400mm!

It is also interesting to note that, unlike in the Baden trials, the range corresponding to a striking velocity of 472 mps is not 14,173 meters (15,500 yards) but much more than that. So perhaps these penetration curves are based on a newer 15" AP shell using a different charge?

José

User avatar
Ulrich Rudofsky
Contributor & Translator
Posts: 844
Joined: Sat Oct 16, 2004 9:16 pm
Location: State of New York

Postby Ulrich Rudofsky » Tue Mar 15, 2005 1:53 am

Marty: I don't know if we ever posted a translation of this bulletin on the Bismarck site? "Documentation and Guidelines for the Determination of the Main Battle Distances and the Choice of Projectiles" [Unterlagen und Richtlinien zur Bestimmung der Hauptkampfentfernung und Geschoßwahl]? I can send you a draft copy by email.
Ulrich

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Tue Mar 15, 2005 2:07 am

Hi Jose:

I had not noticed it before but the NavWeps page velocity is given as only 1537-fps at 14853-yrds. Good eye on your part. Yet the British Baden trials clearly imply 1550-fps is associated with a range of 15500-yrds.

NavWep Data Again
Range (yrds)-------Velocity (fps)-----------Penetration (inches)
8629----------------1853--------------------------16
14853------------1537--------------------------12
19707---------------1329--------------------------11
23734---------------1178---------------------------9

What details are there in the Baden Report for the 15-inch APC used during the trials?

Regarding the velocity drop discrepancy between the Baden Trails and the KDOS-100 Report, was a different ballistic cap adopted for post WWI 15" MkI APC? A longer windscreen (increase in CRH) can make a big difference in velocity drop, particularly over these sorts of ranges.

On the Penetration Tables: it looks to me like you are reading the KDOS figures correctly. I make out the WWII era 15-inch APC Mk-I with impact V=472m/s @ 11-deg to be about 430mm of KC armour, or about 16.9-inches. Much higher than the NavWeapons web page estimates and somewhat greater than my Krupp Equation Estimate when using a Krupp Constant of 710.

One last comment on the KDOS-100 penetration values: N.Okun gives a Krupp Constant of C=687 for the Hoods circa-WWII era 15-inch APC. Using this Constant in the Krupp Equation yields penetration at @472m/s @ 0-degrees of about 450mm, which is precisely the penetration value listed in the KDOS-100 report for intact British 15-inch APC vs KC n/a armour. It seems likely that this is how N.Okun derived his Krupp Empirical Constants listed on his web page (another mystery solved). It is also possible to break away from the use of 90mm M82 APC vs FH for derivation of slope effects of APC vs KC armor (mystery number 2 solved). The KDOS-100 Penetration figure will do quite nicely for back calculating slope effects.

This has been very informative Jose. Thanks for bringing the Baden Trials to my attention.
Last edited by marty1 on Tue Mar 15, 2005 3:00 am, edited 1 time in total.

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Tue Mar 15, 2005 2:30 am

Here it is. I got these from the internet sometime ago. Dumped them onto my hardrive. I dont recall the URL -- if someone recognizes either of the images and knows the URL let me know so I can give them the approrpriate credit and cite.

This is apparently the old model 15-inch MkI APC

Image

marty1
Member
Posts: 219
Joined: Tue Nov 02, 2004 6:31 am
Location: Seattle

Postby marty1 » Tue Mar 15, 2005 2:43 am

This is an improved version of MkI 15-inch APC. It has a slightly different nose shape. The windscreen is slightly longer. The meplet is also slightly more pronounced on the new cap -- and the windscreen's ogive looks a bit more conical on the new cap. I dont think this will amount to large difference in Velcoity Drop (Vdrop) between the old cap and new cap -- at least not without crunching the numbers. However if an even longer windscreen was developed post war it may account for lower velocity drop with range.

Than again the KDOS-100 figure may simply be an underestimation on the part of Germans of the 15" MKI's APC Vdrop charachteristics.

Image


Return to “Naval Weapons”

Who is online

Users browsing this forum: No registered users and 1 guest