Bismarck Myths

[Thorsten Wahl]

At around 40 sec of flight time the target was able to leave the precalculated landing zone of the projectiles by own maneuver. This forces the enemy to increase dispersion artificial in range and deflection.

[Bgile]

The loading clock for the Iowa class shows 29 seconds between salvos and includes approx 2.5 seconds for elevation of the gun and approx 2.5 seconds for return to loading position. Loading angle is +5 degrees and elevation rate is 12 degrees per second. I assumed firing cycles for major caliber guns always included that time duration. I take it that is not true.

Obviously if they were firing at less than (5 + 2.5 * 12) = 35 degrees, the time could be as short as 24 seconds, but I thought that was true for all battleship guns. Apparently not so for the British 15" gun. I wonder why they discontinued the variable loading angle in the 14" gun if it provided a significant advantage in combat as implied in the post above.

When the British compared actual loading times for their 15" gun and the 15" gun on Baden after WWI, they came up with times greater than 30 seconds for their gun. I can't recall the actual time, but it was 35 seconds or more. Did they make a mistake and they could actually load faster than they thought they could?

[tommy303]

In the original design for the 15-inch mountings, the British went to a lot of trouble to develop a method of any angle of elevation loading--this being a natural extension of any bearing loading as introduced years earlier. However, once they introduced it to the QE and the Rs, they found it wanting. The problem was, that at some point near to maximum elevation, the hydraulic run out proved insufficient to meet all demands when the guns were being fired at their maximum rate, resulting in the guns stalling as run out was uphill, so to speak. There was also the problem of shell seating. If the shell driving band was not seated very firmly in the bore, the shell could slide back out at higher barrel elevations when the rammer was withdrawn.

Hood appeared with I believe pneumatic run out, and the ships modernized in the 30s for 30* elevation were also given pneumatic. This prevented the stalling problem, but may not have overcome the problem of the shell backing out. At the time of the Baden trials, the 15s were being loaded at 5* like every other main gun in the RN, so that added to the loading cycle. I do not know if the seating problem was ever solved, but I suspect not completely since the all elevation loading was not continued in battleship guns after Hood, and designers must have felt that the increased loading times it could theoretically permit was hardly worth the extra effort in designing the feature into newer heavy gun mounts.

As an aside, the Japanese also used any elevation loading in their 14 and 16-inch turrets, but dropped the feature when the mountings were modernized in the 1930s, reverting back to the more usual 3 - 5* fixed angle; it was not apparently even contemplated for the Yamato class. Likewise, the Italians had any angle loading for their 12-inch dreadnoughts, but must have been similarly dissatisfied with the results, for when they rebuilt and modernized their dreadnoughts, they gave the new guns a fixed loading angle of 12* while the new Littorios were given 15*. One can presume that a shell slipping back out of the breech was not a problem at 12 and 15*. Of other naval combatants, the Germans chose not to, probably because of complications resulting from the need to eject and dispose of spent cartridge cases, while the USN does not appear to have embraced the idea at all with its dreadnoughts and treaty battleships. Only the French seem to have persisted in the practice; they seem to have come late to the idea, for their dreadnoughts had fixed loading angles, but the Richelieus and Dunkerques were given any elevation loading; like the British and Italians, they found that 15* was about the maximum angle shells could be rammed without backing out when other guns were firing.

[tommy303]

I need to correct myself:

The USN did briefly experiment with any elevation loading with the 12-inch guns of its early dreadnoughts, but reverted back to fixed loading angles with the introduction of the 14inch battleships.

[RobertsonN]

In practice, the twin 15 in mounting performed well at Narvik, the Renown against S/G, at Calabria, Oran and Matapan. The presence of Malaya saved one convey from an attack by S/G. While I don't have any detailed accounts, the ones I do don't mention problems. One of the Hood survivors stood next to Holland and heard reports coming in, none of which mentioned problems firing the guns. The ships that had them were generally good sea boats and the forward turrets little troubled by wetness. S/H were unable to use their foremost turrets against Renown. Photographs of modern American battleships in moderate conditions in the Pacific show them to have been wet forward due to fine lines and the greater weight of triple turrets. In the Atlantic this might have been more of a handicap. Similar comments apply to the VVs. Raven and Roberts thought the British twin 15 in the most efficient and reliable of all heavy guns/mountings.
POW fired 55 shells out of an attempted 74 for an output of 74% and three hits (3 out of 55 is respectable). However, having done this only two guns were still working (Dulin & Garzke). The output of DOY at the North Cape was 68%. Roberts in an article in Warship (1983) gives a detailed account of the performance of KGV and Rodney against Bismarck. At the end of the action only five guns on KGV were still operating, whereas all those on Rodney were still apparently functional. It was Rodney's brilliant opening phase that decided the action and this by a ship which was on its way to America for a refit that did not have all the normal crew on it. Brown in From Nelson to Vangaurd says that the problem with the loading system of the KGVs was of a structural/design nature. The designers had not allowed for the fact that the hull flexed several inches due to heavy seas and also expansion due to the upper deck heating up due to strong sunlight (not a problem at the North Cape!). This lead to repeated jams in the loading mechanisms. Why? I can only speculate. The KGVs were excellent in armor thickness and extent. During the design process, the armour deck was raised from middle deck to main deck level, really putting a quart into a pint pot as far as armor extent was concerned. (Only Yamato was clearly thicker but extent was less.) This, despite the reduction to 10 guns, still made them overweight and top heavy. So the hull depth was reduced to 51 ft (Nelson was 55.5 ft). This would have increased the stress in the upper deck, which was probably of borderline thickness anyhow (Vanguard was also wanting in this respect). The large openings in the decks for the quadruple turrets did not help. The original full load displacement of 40580 tons rose to about 45000 tons later in the war, which might have aggravated this problem.
As far as the Hood's tactics are concerned there is some support for my view from the German battle handling of Scharnhorst against Revenge: it says "Hauptkampfentfernung unter 150 hm. Auf eigene Lage (3 to 4 dez.) achten". This says: "under 16500 yards. Keep the enemy between 30 and 50 deg either forward or aft of the beam". It goes on to say that there may be some advantage in fighting over 20000 m because here the Revenge's deck armor can be penetrated (although so to a lesser extent can Scharnhorst's): historical support for Thorsten's view.
Holland's choices were, however, restricted by the tactical inhomogeneity of Hood and POW. The two shadowing British cruisers might have closed to give support but chose to stand off.

[RF]

It was Rodney's brilliant opening phase that decided the action

Not quite sure on this one. Bismarck straddled first after opening fire after Rodney, and it did take some time for Rodney to find the target.

[Bgile]

I don't think the British cruisers at DS chose to stand off. The Germans were going very fast and were difficult to catch.

[RobertsonN]

RF and Bgile are correct; exaggerating to call Rodney's fire brilliant and British cruisers probably unable to make up seaway quickly enough to take part in the action.
A point I wondered about rof. The guns are loaded and then elevated. But then is there not a wait until the ship next rolls through the even keel position before the guns are fired? This might add up to half a roll period, say 7 seconds, to the firing cycle time.

[tommy303]

A point I wondered about rof. The guns are loaded and then elevated. But then is there not a wait until the ship next rolls through the even keel position before the guns are fired? This might add up to half a roll period, say 7 seconds, to the firing cycle time.

Depends on what kind of sight is in use. If it is a gyro P sight, or equivalent, no you would not have to wait as long as the sight was working and the roll of the ship was not to severe. If the P sight was not present or not working, the director layer would manually keep the sight on target and the guns would follow the changes as the ship rolled. If the roll was too quick, the layer would fire the guns as his horizontal wire was about to touch the horizon line.

You might find the Gunnery Pocket Book interesting, and although it is a few years after the time period in question, it gives a good over view of systems, including sights.

http://www.hnsa.org/doc/br224/index.htm

[RF]

I don't think the British cruisers at DS chose to stand off. The Germans were going very fast and were difficult to catch.

Norfolk did fire up to six salvoes from A and B turrets, but the shells could come nowhere near Bismarck, let alone the target that Holland wanted them to attack, namely Prinz Eugen.

[tommy303]

Norfolk did fire up to six salvoes from A and B turrets, but the shells could come nowhere near Bismarck, let alone the target that Holland wanted them to attack, namely Prinz Eugen.

I believe with radar ranging and visual for line at what they thought was Prinz Eugen, but what turned out instead to be a coastal command bomber which flew between Norfolk and Prinz Eugen. The German cruiser was well out of range, and six salvos were fired before the mistake was realized.

[RF]

The PE was two miles in front of Bismarck and hardly in a position to be sighted and targetted by Norfolk.

Wake-Walker opened fire on Bismarck not an aircraft and the fall of shot was plotted. The distraction attempt failed as Norfolk was well out of range.

[Tiornu]

Rodney's opening gunnery against Bismarck was pretty pathetic. I believe they didn't even straddle until the 17th salvo.

[lwd]

I seem to remember reading that they got a good range from KGV and that helped. Don't remember where I read that though.

[paulcadogan]

believe with radar ranging and visual for line at what they thought was Prinz Eugen, but what turned out instead to be a coastal command bomber which flew between Norfolk and Prinz Eugen. The German cruiser was well out of range, and six salvos were fired before the mistake was realized.

That was actually Suffolk. At 6:16 her 284-radar picked up a target closing with her from the direction of the Germans which she thought was Prinz Eugen. She opened fire at what the radar said was 19,000 yards range, despite her plot showing PE as out of range, firing 6 salvoes. The range decreased so rapidly it became clear something was wrong, then the Sunderland was identified.

I believe Suffolk's gunfire made Bismarck train her guns on her (as shown on one of the battle photos) but the latter did not open fire. I guess it was quickly realized that Suffolk was too far away to be a threat.

The Norfolk fired only three salvoes at about the time PoW was circling the sinking Hood. They were directed at Bismarck but fell well short, probably because the ship was much further away than her range-takers thought.