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TECHNICAL REPORT No. 372-45

GERMAN FIRE EFFECT TABLES

August 1945

This document has been transcribed in this format from a copy
provided courtesy of William J. Jurens.

USNTME Cover


UNITED STATES NAVAL TECHNICAL MISSION IN EUROPE

File: S71 (40AW/wef)

Serial: 0892

21 August 1945.

CONFIDENTIAL

From: Chief, U.S. Naval Technical Mission in Europe.

To: Chief of Naval Operations (Attn: Op-16-PT).

Subject: German Fire Effect Tables.

Enclosure: (A) (EW) Two rolls of microfilm comprising one set of copies of 8 volumes of a German document Awa A IA 100/40 g.Kdos Unterlagen und Richtlinien zur Bestimmung der Hauptkampfentfernung und der Geschosswahl (Basis and Guiding Principles for the Determination of the Fighting Range and Choice of Projectiles) and one set of German Penetration Curves.

1. Enclosure (A) is forwarded herewith for information.

2. A Technical Report (Number 372-45) is under preparation.

3. It is recommended that enlarged copies of theses microfilms be made and distributed to recipients of copies of this letter.

[Signed]
L.V. HONSINGER
By direction.

CC: (W/O Enclosure)
BuOrd
Naval Proving Ground
Naval War College
Bureau of Ships
ComInCh (Readiness)


TECHNICAL REPORT No. 372-45

GERMAN FIRE EFFECT TABLES

SUMARY

German Fire Effect Tables classified as "Goheime Kommandosache" which is equivalent roughly to our "Secret" consist of 8 volumes. Microfilm copies have been forwarded as enclosure (A) to NavTecMisEu letter of 20 August 1945 serial No. 0892. The first volume contains a general discussion of fundamental principles underlying the construction of theses tables. The other volumes contain general ballistic and penetration data for German and foreign guns as well as fire effect diagrams for specific combinations of German and foreign ships. The introductory volume also discusses the basis underlying the distribution and the arrangements of armor aboard ships as well as the best choice of projectile for various types of targets. Miscellaneous data on effects of fragments, smoke and incendiary action are also given. The date of the Tables is 1940.

August 1945

U.S. NAVAL TECHNICAL MISSION IN EUROPE


CONFIDENTIAL

TABLE OF CONTENTS

1. Introduction.

    (a) Armor
    (b) Projectiles
    (c) Guns
    (d) Targets
2. Armor.

3. Armor Arrangement.

4. Projectiles - General.

5. Delay of Fuzes.

6. Effects of Detonation.

7. AP Projectiles.

8. Effect of AP Projectile Hits.

9. Effects of an effective AP penetrative hit.

    (a) Blast
    (b) Fragments
    (c) Incendiary Effect
    (d) Smoke
10. Effect of an AP Projectile Penetrating in Broken Condition.

11. Common Type Projectiles - General

12. Effect of Penetrative Effective Hits of Common Projections.

13. HC Projectiles - General.

14. Effects of Hits of HC Projectiles.

    (a) Blast
    (b) Fragments
    (c) Incendiary Effect
    (d) Smoke
15. General Remarks on use of Different Types of Projectiles.
    (a) Armor Piercing Projectiles
    (b) Common Projectile
    (c) High Capacity Projectiles
16. Choice of Projectiles for Different Targets.

17. The Best Choice of Fighting Range.

18. Power of Guns.

19. Rate of Fire.

20. Divided Armor.

21. Dispersion of German Guns.

22. Conclusions and Recommendations.

    (a) Ballistic Matching of all three types of Projectiles
    (b) The use of three types of Projectiles
    (c) Armor Piercing Projectiles
    (d) German Deviation of Projectile Design.
    (e) The General Set-up of the Fire Effect Tables.
    (f) Arrangement of Armor.


CONFIDENTIAL

GERMAN FIRE EFFECT TABLES

1. Introduction.

Microfilm copies of these tables, as well as penetration curves for all German naval projectiles have been forwarded as an enclosure to NavTec letter Serial 0892. All volumes are complete. It is of interest to note that in the construction of these tables they assume that the quality of the foreign armour and projectiles was "the best known, namely, German", in order to avoid disappointment. They felt quite sure that they were the leaders in the field of armour and projectiles.

The following general subjects are discussed in the first volume as a basis for the best choice of projectiles and fighting range:

    (a) Armor.
    (1) Type and quality.
    (2) Arrangement aboard ship.

    (b) Projectiles.
    (1) Discussion of the various types.
    (2) Their effect on detonation.

    (c) Guns.
    (1) Velocity.
    (2) Maximum range.
    (3) Dispersion.

    (d) Targets.
    (1) The target overmatches the projectiles.
    (2) The target and projectiles are matched.
    (3) The Projectiles overmatch the target.

2. Armor.

General detailed reports about the quality and production methods of German armor have previously been prepared and will not be repeated here. Of interest is the statement that in general, for main protection over 100 mms thick, class A armor is used.

3. Armour Arrangement.

In the discussion on this subject, they state that the advance of long-range gunnery and bombing forced them to use a greater part of the available armor weight for horizontal protection. They therefore accepted it as a fact that neither the vertical armor alone nor the horizontal armor alone can keep out the heaviest missiles that may be fired against them under all conditions. They decided to distribute the armor in such a way that, at the most important fighting ranges, both the vertical and horizontal armor will help protect the vitals of the ship, and take a chance with the gun fire at very long ranges and also with bombing from very high altitudes. For this reason, they attached the heavy armored deck to the lower half of the armored side belt, instead of the upper edge. In discussing the difference between the German and the foreign armor arrangement they state that, while the foreign practice causes more missiles to detonate higher up in the ship, it has the serious disadvantage that where the main belt is hit directly the deck does not contribute anything to protection. They adopted the policy of having the main deck above the armored deck about 50 mms. thick in order to keep out most of the GP type bombs (50% filler). They figured that the SAP bombs (about 25% filler) would probably penetrate this deck and they therefore put in about 30 mms. thick longitudinal and athwartship bulkheads for protection against fragments from such types of bombs. They felt that the main protective deck might also be penetrated by heavy AP bombs (about 6% filler) but that it would require either very high altitude or rocket assistance to accomplish this.

4. Projectiles - General.

In the first volume there is a table showing all German naval standard projectiles, consisting of 15 cms., 20.3 cms., 28 cms., and 38 cms. They show for each calibre three types of projectiles, which may be roughly classified as AP, Common and HC (nose fuze only). The length of the modern projectiles is about 4 calibers and the W/D3 ratio in pounds-inches is about 0.5. They state that all three types in any one caliber are ballistically matched and require only the use of one range table. The pertinent data for the different types of projectiles are given in the following table:

Gun Type of
Projectile
Length Total
Weight
Weight of
cap
Weight of
Explosive
(cal) (kg) (kg) % (kg) %
15 cm SK C/25 HC
C
AP
4.5
4.4
3.7
45.5
45.5
45.5
-
-
5.31
-
-
11.7
3.89
3.06
0.88
8.6
6.7
2.0
20.3 cm SK C/34 HC
C
AP
4.7
4.7
4.4
122.0
122.0
122.0
-
-
16.3
-
-
13.4
8.93
6.54
2.30
8.3
5.4
1.9
28 cm SK C/28 HC
C
AP
4.2
4.2
3.7
300.0
300.0
300.0
-
-
31.95
-
-
10.7
23.33
16.94
7.84
7.8
5.6
2.6
28 cm SK C/34 HC
C
AP
4.4
4.4
4.4
315
315
330
-
-
44.65
-
-
13.5
21.8
16.0
6.6
6.9
5.1
2.0
38 cm SK C/35 HC
C
AP
4.6
4.6
4.4
800
800
800
-
69.35
112.5
-
8.7
14.0
64.25
32.6
18.8
8.0
4.1
2.35

5. Delay of Fuzes.

There is no discussions on the delay of the fuzes used in the Common and AP projectiles. This is rather puzzling, as the question of the fuze delay would obviously enter in the choice of projectiles for certain targets. Captain Moisman was interrogated on this point and he stated that German AP projectiles previously had a fuze delay of 0.035 seconds. Later on, however, they developed a variable delay fuze which could be set just prior to loading on either 0, 0.015 or 0.035 seconds.

6. Effects of Detonation.

For each type of projectile the effect o the blast, fragments, incendiary action, smoke and chemical gas are discussed. There is no definitive statement, however, as to any tests that they conducted for the introduction of gas in naval projectiles or whether they have actually made up any. It is stated that, considering the small amount of chemical material that may be incorporated, the effect on the whole would be small but might on occasions force masking, if detonated in a closed compartment. Captain Moisman was interrogated on this point and he stated that they conducted extensive tests with the introduction of gas in AP projectiles and they finally developed a capsule which could be introduced in place of the inert capsules which are usually inserted in the cavities of their AP projectiles. Since they invariably used precast explosives, it would be a simple matter to substitute the gas capsule for the inert material. To his knowledge, however, they have never actually loaded any projectiles with gas.

7. AP Projectiles.

General information on the details of design and heat treatment of projectiles have previously been furnished and will not be repeated here. Also samples of most German naval AP projectiles are on the way to the Naval Proving Ground, which will presumably be examined and tested for their metallurgical and ballistic properties.

In general, the long range development of German AP projectiles followed very closely our own trend. Starting with the short capped projectile (about 7% cap) without wind-shield, they finally developed that long projectile with about 14% cap and wind-shield. No mention is made in this report about any spotting feature for German projectiles. Percent filler varies from 1.9% for modern projectiles to 2.6% for the older types, and the W/D3 ratio varies from .48 to .53.

8. Effect of AP Projectile hits.

In discussing the effect of AP projectile hits on the target they divided it up into three different classes:

    (a) Conditions under which the projectile will completely penetrate the target and remain in effective bursting condition.

    (b) Conditions under which the projectile will penetrate the target but will break up on impact.

    (c) Conditions under which the projectile will not hole the target and no part of the back of the armor plate will be dislodged.

They actually give separate sets of curves for conditions (a) and (b). For a 16" projectile against plate of caliber thickness, the two curves practically coincide at normal impact but at 30% obliquity it requires about 10% more striking velocity to obtain an effective penetration than one in which the projectile breaks up. They state that they do not have enough data to give curves for condition (c).

9. Effects of an effective AP penetrative hit.

(a) Blast. Due to the relatively small amount and strong confinement of the explosive, they consider the blast effect only of minor importance and believe that the effect will probably extend only to a few meters.

(b) Fragments. A curve giving the thickness of homogeneous armor for complete protection against fragments of AP projectiles of different calibers is given. The values from these curves are reproduced in the following table:

Calibre in Cms.
Thickness of Homogeneous
Armor in Mms.
15
21
27
33
39
12.5
16.0
20.0
25.0
32.5

It is stated that the above figures are based on results obtained from static fragmentation tests. They also point out that the pieces of armor from the back of the plate may cause quite appreciable damage.

(c) Incendiary Effect. They consider that, due to the short duration of the detonation flame, the incendiary effect will not be very strong. They feel, however, that the flame as well as the hot fragments will cause fires to easily combustible material. Also the fragments may penetrate cartridge cases, etc.

(d) Smoke. The effects of smoke will, of course, depend on the available facilities for ventilation. They consider that the concentration of CO is probably negligible, as it is transformed quickly into CO2, and that the worst possible effect may be the necessity of wearing a gas mask in the vicinity of the explosion.

10. Effects of an AP Projectile Penetrating in Broken Condition.

They consider that, in general under these circumstances there will be either no detonation or partial detonation. The effects of such a hit are entirely unpredictable, as it depends on the type of target and what is behind it whether it can be seriously damaged by the large, but relatively low velocity, fragments that may get through.

11. Common Type Projectiles - General.

As previously pointed out, the Common projectiles have about the same weight and length as the AP projectiles. Here again, the general line of long range development parallels closely our own, with the exception of one case where they actually put a 8% cap on a 15" Common projectile, for the purpose of penetration of relatively light Class "A" armor. They started with the one-piece body without wind-shield, in the next step a wind-shield was added and the threads for the attachment of the wind-shield were cut directly in the body; finally they adopted the method now standard with us of having a separate hodd for the attachment of the wind-shield, the hood being soldered to the body. The percent filler varies from 4% (for the projectile with the 8% cap) to 6 %, and the W/D3 ratio is the same as for the AP projectiles, being about 0.5.

12. Effect of Penetrative Effective Hits of Common Projectiles.

As far as blast, incendiary and smoke effects are concerned, the same remarks as for AP projectiles apply in general, except that due to the slightly larger amount of explosive, the effect may also be expected to be a little larger than for the AP projectiles. On the basis of static fragmentation tests conducted, they estimate that for the same caliber it requires about 18% more thickness of armor for protection against fragments from Common projectiles than from the AP projectile.

13. HC Projectiles - General.

These types of projectiles are very similar to our own HCs, except that, as previously stated, they have no base fuze and they have the same weight and shape as the AP projectiles. The percent filler varies between about 7% and 8 %.

14. Effects of Hits of HC Projectiles.

(a) Blast. Due to the larger percent filler of these projectiles, the blast is quite appreciable, but since the explosion does not take place in a confined space, its effect is not very significant. The size of the hole in a given plate due to the detonation of these projectiles depends of course, on the thickness of the plate. They found that, for thin plates, the size of the hole was practically independent of the striking velocity, while against relatively heavier armor plate the velocity has a pronounced effect. This is in general agreement with the data obtained from our own tests. The following table gives some results on the size of hole for different calibers as a function of velocity and plate thickness:

Cal. Velocity
M.S.
Thickness of Homogeneous Armor (mm)
15 20 25 30 40 50 60 80 100 105 110 125
15 cm HC 770
700
600
500
400




1200




900




W


600
W

400
W


300


200
W







20.3 cm L/47 700
600
550
500









T


1200
W


1000

320
W
T
W






28 cm L/4.2 700
600







W
600

400

W
28 cm L/4.4 700
550
500






1700
W

W
W




38 cm HC L/4.6 700
550









W

W

Diameter of Hole (mm)

The symbol "W" signifies that there was no tear in the plate.

(b) Fragments. From actual experiments (probably static fragmentation tests), they found that the following plate thicknesses are necessary for protection against fragments from HC projectiles:

Calibre in Cms.
Thickness of Homogeneous
Armor in Mms.
15
21
27
33
39
17
22
27
34
42

These figures are approximately 35% higher than those for the AP projectiles.

(c) Incendiary Effect. They consider that the incendiary effect will obviously be greater than for AP projectiles, due to the higher explosive content and larger number of fragments. However, due to the detonation being in open space, there is not so much incendiary material around to catch fire easily.

(d) Smoke. Here again, while the quantity of smoke will be larger, its effect will be very small due to the detonation being in the open.

15. General Remarks on use of Different Types of Projectiles.

(a) Armor Piercing Projectile. This is for primary use against strongly armored targets. Even if the projectile cannot penetrate in effective condition on all parts of the target, they consider that quite serious damage can be inflicted, even when the projectile breaks up. Also, on every target there are always some weak spots where the projectile will penetrate in effective bursting condition.

The disadvantages of armor piercing projectiles are their small explosive filler, and the fact that when they hit a lightly armored part of a ship the fuze may not be initiated at all or the projectile may go completely through the target before detonation. Another point that they mention, which was also emphasized in a recent BuOrd circular letter, is that the hole from an armour piercing projectile is on the average equal to the diameter of the projectile, while with High Capacity projectiles against thin plates large holes may be opened up.

(b) Common Projectiles. The advantage of Common projectiles is the slightly larger explosive content and the consequent increase in the number and velocity of the fragments. They emphasize that the Common projectile should be used only when the maximum armor of the target is such that it can be penetrated in effective condition by these projectiles. If one is not certain of that then the armor piercing projectiles should be used.

(c) High Capacity Projectiles. The high capacity projectile is primarily to be used where fragment effect is desired, that is, against personnel, AA positions, fire control instruments, searchlights, etc. They consider that this projectile should be used against lightly armored ships up to and including Destroyers, as it is possible with these projectiles to do serious damage to the machinery and engine spaces and seriously affect the water-tight integrity of the ship. For larger ships, like merchantmen, they do not consider the High Capacity projectiles very suitable, as, due to their large size, they do not think that the effect can be felt in the vital spaces like the engine and boiler rooms.

16. Choice of Projectiles for Different Targets.

The subject is divided up into a few parts, considering separately the following types of targets:

    The main armor of the target cannot be penetrated by own projectiles (Target A).
    Some part of the fighting efficiency of the target can be destroyed by own penetrating projectiles (Target B).
    The main armor of the target can in general be penetrated by own projectiles (Target C)
    The main armor of the target can be penetrated by own projectile at all ranges of interest (Target D).
    A lightly armored target which can be destroyed by high capacity projectiles (Target E).
Target A. Where the armor of the target is relatively much stronger than the projectiles - such as in the fight of a Cruiser against a Battleship - the effect of the armor piercing projectiles will be very small and they recommend the use of HC projectiles. They call attention, however, to the fact that no serious damage, that is, sinking damage, can be expected even with numerous hits, but its fighting power may be seriously affected. In this connection, they give the results of tests in 1937 where 3 Destroyers were firing against the "HANOVER" with their 12.7 cm projectiles. They got about 206 hits; the ship was quite appreciably damaged but, even with this number of hits which damaged the AA battery, aircraft, smoke stacks, masts and bridges, she was afloat.

Target B. Where the target only slightly over-matches the projectiles, as in the case of a Battle Cruiser against a Battleship, they consider the use of AP projectiles desirable and only in certain tactical conditions, where it is considered desirable to damage the AA installations, etc. should High Capacity projectiles be used.

Target C. In the case of evenly matched ships, the armor piercing projectiles are, of course, the logical and only choice for heavy ships. In the case of Cruisers, if it is considered that the target's armor can be penetrated in effective condition by the Common projectile, then that projectile is preferred. Again the HC projectile would only be used under special tactical conditions. Some results of tests on the "HANOVER" with 28 and 38 Cms. AP projectiles in the engine and boiler room spaces are given. In the case of the engine room, the detonation of the 28 cms. projectile cause the engine room to be abandoned due to steam; the main machinery was damaged but it could be repaired during a yard overhaul. In the case of the 38 cms. projectile, the main engine was completely destroyed, requiring a new installation. In the boiler rooms, the effect of the 28 cms. projectile was to force abandoning of the boiler room and again, the damage could be repaired during a yard overhaul. In the case of the 38 cms. projectile, complete reconstruction would have been required.

To show the ineffectiveness of the HC projectiles as far as causing sinking damage is concerned, they cite the example of the "CHESTER" having 76 mms. side armor and 50 to 26 mms. deck armor. They claim that she was hit by seventeen 15 cms. H.C. projectiles. The result was that 3 guns were put out of commission, the fire control destroyed and 77 men killed or wounded. However, the maneuverability of the ship was not seriously impaired and she managed to get away. If the German Cruisers had used armor piercing projectiles, they figure the ship would never have gotten away. They emphasize the fact that sometimes it takes just one "lucky hit" to sink a big ship. They cite as examples the "INVINCIBLE", "QUEEN MARY" and "INDEFATIGABLE" at the Battle of Skagerrak. They state, however, that while those sinkings were the results of Barbette hits due to probable damage control steps taken, it would require today a hit directly in the magazines in order to accomplish the same results.

Target D. Where the projectiles overmatch the target as in the case of Battle Cruiser vs. Cruiser if the Common type projectile is sufficient to penetrate the target, then it should be used. If, on the other hand, there is any doubt whether the Common projectile is sufficient, the AP projectile should be used. Again the High Capacity projectile is only to be used for topside damage if for some reason top side damage is considered of primary importance.

Target E. When the target can be destroyed by HC projectiles as in the case of Battleship vs. Cruiser, or Cruiser vs. Destroyer and Merchantman, H.C. projectiles should be used. They consider that in some cases only a few hits of these projectiles are sufficient to cause sinking damage, particularly with some hits on the waterline. Against merchant ships particularly they emphasize that the morale effect of the High capacity projectile as compared to deeply penetrating projectiles, is worthy of consideration. However, in order to insure some deep penetrations, they consider that a mixture of H.C. and Common projectiles would be desirable.

17. The Best Choice of Fighting Range.

They discussed in general the familiar questions of the region where the vertical armor can be penetrated and the region where the horizontal armor can be penetrated. They point out that consideration must be given to the fact that the region of deck penetration may be so far out that the percentage of hits will be very small. They also discuss the difference between the side armor and the barbette, due to the fact that the barbette will always be normal to the line of fire. Detailed instructions on how to compute these regions from the range table and penetration data are given. An example is worked out in detail for the case of "BAYERN" vs. "TIRPITZ" to illustrate the general procedure. There is nothing new in the reasoning or the conclusions, which follow the general pattern of computing your own and target's penetration zones of vertical and horizontal armor and then choosing a fighting range and target angle which will give the most advantageous conditions for your own ship. Towards the end, the usual word of caution is given that, after all calculations are made, there are many factors which make results doubtful, such as the quality and exact construction of the target material. Also there are many tactical considerations, such as visibility, wind, etc. which must be taken into consideration. It is of interest that they considered themselves so far superior that they state that it is best to choose the longest range compatible with all other conditions, as at the long range the superiority of men and material of the Germans will pay dividends, while the shorter ranges even an inferior enemy may succeed in getting hits. They also emphasize the fact that, under no circumstances, should it be assumed that if you can not use the best projectiles the fight is hopeless. They give the usual story that the will to win and the reckless attack to annihilate the enemy is more important for the success of a mission than the specific choice of the best projectile.

18. Power of Guns.

They apparently did not feel very sure of the Intelligence about foreign guns. They, therefore, plotted the power (muzzle energy) of their own guns as a function of the caliber for different lengths of guns and they have drawn average curves for 45, 50 and 55 caliber. If, on a basis of some Intelligence, the power of a gun fell without the expected dispersion of their mean curves, they did not fully trust the information.

19. Rate of Fire.

They complain that the Intelligence about the rate of fire of foreign guns is very vague. They are not sure whether these are theoretical figures or actual rates obtained in service. The following data is given for the German ships:

Ship Caliber Rate of Fire -
Round per Minute
BISMARCK
GNEISENAU
38 2
SCHARNHORST
GNEISENAU
28 2
Battle Cruisers
Heavy Cruisers
Light Cruisers
28
20.3
15
2
4
7
They assumed for foreign ships corresponding rates of fire.

20. Divided Armor.

For divided armor they use a formula which corresponds to the assumption that the energy required to penetrate a divided armor structure is equal to the sum of the energies required for the individual plates. They point out the difficulties in determining the deck penetration region, due to the curves being very flat and also that when penetrating through a number of plates the effect of any yaw imparted to the projectile may be appreciable.

21. Dispersion of German Guns.

They give curves for the probable error as a function of elevation for all German Naval guns. For the most important elevations - that is between 15 and 30 - probable error varies between 0.50 and 0.80% of range for the modern guns and projectiles. These, however, are Proving Ground probable errors. They use a factor to convert Proving Ground probable error to Battery probable error, which varies with the range and the battery. However, the variations are not large and the factor usually lies between 1.5 and 1.7. This factor is with delay coils which they introduced in 1939-1940. Without delay coils the factor was about 2 to 3 in addition to numerous wild shots.

22. Conclusions and Recommendations.

As pointed out in the report, the general line of development of the different types of German projectiles followed very closely that of our own. Some of the outstanding differences are listed and discussed in the following paragraphs:

(a) Ballistic Matching of all Three Types of Projectiles.

The W/D3 ratio for German AP projectile is about 0.50 as compared to 0.060 to 0.68 for U.S. Navy projectiles. With such a relative low W/D3 ratio, it is quite possible to make the HC projectile the same weight as the AP and still get an acceptable percent filler. On interrogation of Captain Moisman and R. Steinhardt, it was brought cut that their choice of the relatively low W/D3 ratio for the AP projectiles was partly influenced by the fact that they wanted to match it with the HC. They had started developing a new gun of 52 cms and for that gun they considered a heavier W/D3 ratio for the AP projectiles. While ballistically matched projectiles are obviously desirable, it is questionable whether the advantage (with modern fire control, where it is only necessary to turn a knob in order to get the correct ballistics for the HC projectiles) is worth while considering the limitations that it imposes on the design of AP projectiles.

(b) The Use of Three Types of Projectiles.

Here again, while having three types of projectiles may seem to be an advantage in that you can choose the most desirable projectile for any given target, actually however, since the armor and construction of any target is not exactly known this advantage may not be real. Captain Moisman was interrogated on this point and he stated that the service did not like the Common projectiles for that very reason, and for any new construction they would have abandoned it and they might also have taken it of from existing ships. On the other hand, their destroyers only had an HC projectile an they were going to develop a Common projectile for the 12.8 destroyer guns. The information on this point, however, conflicts with that obtained from Dr. Straeter of the Rhienmettall Co., who stated that to his knowledge many Common projectiles for the 12.8 guns were produced and he assumed that they were actually put in service. Captain Moisman was Gunnery Officer of the "GRAF SPEE" and he stated that they used Common projectiles against the British cruisers and he partly attributed the failure on the part of the Germans to sink the British cruisers to the use of these projectiles, as he thought they might have broken up against the British armor.

(c) Armor Piercing Projectiles.

As stated previously, the W/D3 ratio for the German projectiles is much lighter than for the U.S. projectiles. One of the reasons was their desire to match it ballistically with the HC projectile. Another reason, however, may be that it is believed (subject to check from the detailed armor reports now under preparation) that the Germans have not emphasized the projectile-breaking qualities of their Class "A" Armour as much as we did. The tests of German projectiles versus our type of armor at the Naval Proving Ground ought to throw some light on this.

(d) It is seen in general then where the German practice in projectile design and in the choice of types deviated from ours that they were not quite satisfied with it and that their general tendency lately was to follow more in our direction.

(e) The General Set-up of the Fire Effect Tables.

The German Fire Effect Tables, in addition to the usual material regarding best choice of range and target angle, also contain the information regarding the best choice of projectile fo a given target. Such information is usually disseminated in separate circular letters or pamphlets by us. Since the distribution of Fire Effect Tables is usually very limited, it is considered that the policy of having he choice of projectiles in a separate pamphlet is sound. However, a short discussion of this subject in the Fire Effect Tables might be desirable.

(f) Arrangement of Armor.

The question of armor arrangement involved, in addition to questions of protection and ballistics, also fundamental questions of design of ship and stability. As pointed out in the report, both schemes have certain advantages. However, the principal advantages of the German scheme is that no projectile can go through the side belt into the vital places without encountering first some part of the deck structure except for underwater hits. If short-range gunnery was the most important item to be considered, then this scheme would be advantageous. However, as pointed out by the German themselves, since the advent of long-range gunnery and bombing makes the question of horizontal protection much more important, the advantages of the German scheme appear rather dubious.

Prepared by:

A. Wertheimer,
Technican.




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