KGV and PoW GAR during Op. Rheinubung

[Antonio Bonomi]

Hello everybody,

@ all,

many thanks for your usual support and inputs on the previous thread about Tirpitz readiness status during Op. Rheinubung.

viewtopic.php?f=1&p=67404#p67404

Now we migrate here in from there, the discussion about KGV and POW Gunnery Aspect Reports ( GAR ) during Op. Rheinubung.

Bye Antonio

[Antonio Bonomi]

Hello everybody,

here the link suggested by CAG :

http://www.navweaps.com/Weapons/WNBR_14-45_mk7.htm

Bye Antonio

[Alberto Virtuani]

Dunmunro wrote on the "Tirpitz sails on part of Rheinubung" thread: "That was my rough estimate based upon Rodney's 77% output where 385 = 77% and 500 = 100%. If 339 = 62% then 549 = 100%.
I should have better numbers tomorrow."

Hi Duncan,
waiting for your analysis of the GAR, where the 62% comes from then ?

Bye, Alberto

[dunmunro]

Dunmunro wrote on the "Tirpitz sails on part of Rheinubung" thread: "That was my rough estimate based upon Rodney's 77% output where 385 = 77% and 500 = 100%. If 339 = 62% then 549 = 100%.
I should have better numbers tomorrow."

Hi Duncan,
waiting for your analysis of the GAR, where the 62% comes from then ?

Bye, Alberto

The report will require some time to analyse - hopefully something in a few hours

If you read the last few pages of the Tirpitz thread you will note that I estimated Rodney's 100% output and then added 10% to that to give an estimate for KGV.

Rodney fired 375 rounds (not 380 from my first estimate - Roberts gives rnds per gun) from Roberts Rodney had 77% output in salvo fire. If we assume all salvo fire then 375 rounds = 77% so 100% = 487 rounds therefore 100% for KGV would equal Rodney multiplied by (10/9 or 1.111) = 541 rounds.

KGV fired 339 rnds and 339 rnds fired / 541 rnds possible = 62.6%. This is just a rough estimate but it clearly shows that KGV's output was in the ~60+ % range.

My preliminary analysis shows 90+ % output from KGV until 0920.

[Antonio Bonomi]

Hello everybody,

@ Dunmunro,

take your time Duncan, you are the best one on doing those analysis, no one is in a hurry about it.

Any help or additional material or documents you may need, just feel free to ask and I will see what I can do to help you about it.

Here the original KGV battle track for May 27th, 1941, from 08.48 until 10.22, it may be helpful to refer to it to realize the KGV possible bearings.

KGV_May_27th_1941_track_01.jpg (86.09 KiB) Viewed 7693 times

Bye Antonio

[dunmunro]

OK here's a very rough, initial, analysis:



I'll have to leave it now until later tonight or tomorrow.

Red = failure to fire
salmon = wooded or cease fire

Timing is difficult to make exact except where specific times are given, especially the A turret jam at 0920.

KGV fired 34 salvos from 0853 to 0913 - other salvo/min intervals are estimates.

0920: "The 14in, which for a new and untried design of mounting had been doing extremely well in the all important early stages, now commenced to have their troubles..."

0920 A turret jammed after firing an average of 23 rnds/gun

Y turret jammed after firing an average that was very near 23 rnd/gun as well (inferred from the report).

Most gun casualties are not timed so there is a considerable amount of guesswork. However, the number of rnds fired/gun is usually noted for casualties that resulted in lengthy stoppages. OTOH minor stoppages amounted to only ~30 rnds of which only 7 appear to have been prior to 0920.

Gun output after 0920 was poor.

[Alberto Virtuani]

@Dunmunro:
Hi Duncan, I really like your approach and I do hope you can get to a conclusion, especially for the first minutes of the battle: I was wondering how you would have started this work not having many exact timings in the GAR......

I have some doubts however that it will be possible to determine exactly the total number of salvos fired by KGV. For sure, looking at your preliminary spreadsheet, to the battle map posted by Antonio, and reading the GAR, I see that Y turret was not bearing for at least 15 minutes (from 8:48 to 8:53 reading the GAR, from 9:15 to 9:18 and from 10:02 to 10:06 due to turns), it was out of action for 7 minutes (after 9:34, why have you assumed until 9:38 ?), and that fire was interrupted from 10:09 to 10:18.

The total battle time was 94 minutes (8:48 to 10:22), therefore, even without the last mentioned 10 minutes, we have 84 minutes fire. We also know that gun no.4 of Y turret fired 49 shots and even assuming (very improbable situation) that it NEVER missed a single shot (100% output) we should assume that the salvos were at least 49 + 15(Y not bearing) +7 (Y out of action), assuming almost 1 salvo per minute rate of fire, that is an impressive more than 70 salvos in total (not all of them complete, of course, due to some turrets not bearing).

Am I missing something in this reasoning ?

One more question: I would assume also turret B was blinded while turning at 9:54 as well as turret A , am I wrong ?

Bye, Alberto

[dunmunro]

@Dunmunro:
Hi Duncan, I really like your approach and I do hope you can get to a conclusion, especially for the first minutes of the battle: I was wondering how you would have started this work not having many exact timings in the GAR......

I have some doubts however that it will be possible to determine exactly the total number of salvos fired by KGV. For sure, looking at your preliminary spreadsheet, to the battle map posted by Antonio, and reading the GAR, I see that Y turret was not bearing for at least 15 minutes (from 8:48 to 8:53 reading the GAR, from 9:15 to 9:18 and from 10:02 to 10:06 due to turns), it was out of action for 7 minutes (after 9:34, why have you assumed until 9:38 ?), and that fire was interrupted from 10:09 to 10:18.

The total battle time was 94 minutes (8:48 to 10:22), therefore, even without the last mentioned 10 minutes, we have 84 minutes fire. We also know that gun no.4 of Y turret fired 49 shots and even assuming (very improbable situation) that it NEVER missed a single shot (100% output) we should assume that the salvos were at least 49 + 15(Y not bearing) +7 (Y out of action), assuming almost 1 salvo per minute rate of fire, that is an impressive more than 70 salvos in total (not all of them complete, of course, due to some turrets not bearing).

Am I missing something in this reasoning ?

One more question: I would assume also turret B was blinded while turning at 9:54 as well as turret A , am I wrong ?

Bye, Alberto

Y turret was wooded until 0900 according to page 140. KGV turned "...to open A arcs at 0859."

Determining the number of salvos is difficult but we have to remember that most salvos were fired with half guns. If KGV's maximum possible output was ~550 rounds, this would imply about 120 salvos when the periods that Y was wooded are taken into account. However, the rate of fire declined at some points in the battle, especially when radar ranging was not available, during turns and during periods of poor visibility. Rodney reported firing 113 salvos which is a useful guide to how many KGV might have fired.

I assumed that Y turret jammed at ~0934 (about 14 mins after A turret since they jammed after firing about the same number of salvos) but I made an error in the timing column for resuming fire (thanks). I'm still trying to decide exactly when it jammed, but the fact that Y1 ceased fire permanently at that point, after ~48 salvos tells us that it was around 934-937. Y turret ceased fire for 4 to 5 minutes at 0915 when the turret was order to train round ~180 degree to prepare to open fire on the opposite course.

B turret was wooded during the turn but since both guns were out of action I didn't indicate it on the page.

[Alberto Virtuani]

Dunmunro wrote: "Y turret was wooded until 0900 according to page 140. KGV turned "...to open A arcs at 0859.""

Hi Duncan,
I just saw it, however at page 144 the GAR, Gunnery - 14" Control, point 2 ends at 8:53 and point 3 states that "a turn to starboard opened "A" arcs and "Y" turret joined in". Then it accounts for salvos from 8:53 till 9:13. Difficult to understand which is the right timing.....

you wrote: "If KGV's maximum possible output was ~550 rounds, this would imply about 120 salvos"

Where are you getting the 550 as maximum output ? If Y turret gun no.4 fired 49 shells and was wooded or out of action with the whole turret for 22 minutes (see my previous post), or even for 28 minutes if we use your assumption about Y turret joining action at 8:59, we have at least space for 70 full salvos (or 140 semi-salvos), possibly 75 (150).
Am I making any big mistake here ?........

Bye, Alberto

[dunmunro]

Dunmunro wrote: "Y turret was wooded until 0900 according to page 140. KGV turned "...to open A arcs at 0859.""

Hi Duncan,
I just saw it, however at page 144 the GAR, Gunnery - 14" Control, point 2 ends at 8:53 and point 3 states that "a turn to starboard opened "A" arcs and "Y" turret joined in". Then it accounts for salvos from 8:53 till 9:13. Difficult to understand which is the right timing.....

you wrote: "If KGV's maximum possible output was ~550 rounds, this would imply about 120 salvos"

Where are you getting the 550 as maximum output ? If Y turret gun no.4 fired 49 shells and was wooded or out of action with the whole turret for 22 minutes (see my previous post), or even for 28 minutes if we use your assumption about Y turret joining action at 8:59, we have at least space for 70 full salvos (or 140 semi-salvos), possibly 75 (150).
Am I making any big mistake here ?........

Bye, Alberto

The track chart shows Y to be wooded ( KGV's bow is aimed almost directly at Bismarck ) until KGV turns south at 0859 allowing Y to open fire at ~0900.

Again, I based ~550 possible (100% output) for KGV on Rodney's 375 rnds fired @ 77% output. Neither ship fired at maximum salvo rate and during turns and periods of poor visibility. Requested output on Rodney was much lower during some phases than others and I'm sure the same was true of KGV when her type 284 radar failed. Rodney fired 60 salvos from 0847 to 0928 (41 mins) and 53 salvos from 0929 to 1014 (45 mins) however 11 of these salvos were fired between 1008- 1014. Rodney was, on average, considerably closer to Bismarck so she had better spotting visibility and much lower ToF to the target allowing a higher RoF at the closer ranges.

[Alberto Virtuani]

Dunmunro wrote: "I based ~550 possible (100% output) for KGV on Rodney's 375 rnds fired @ 77% output. Neither ship fired at maximum salvo rate and during turns and periods of poor visibility."

Hi Duncan,
my fault, I have not read carefully (and understood....) your previous posts. Thanks for confirming. However the 62% output is just another assumption based on 550, isn't it ? I have not found this figure in the actual GAR. The only sure number is 339 actual shots fired.

If this is the case, we should take into account also that, disregarding the intervals when the 2 ships did not fire at their maximum rate (turns, radar unavailability, etc), the theoretical rate of fire of the 14" Mk VII was much higher than the one of the 16" Mk I (2 rounds per minute vs 1,5 rounds per minute, theoretical of course..... BTW this was one of the reasons why the RN considered that 12 or even just 10 14" guns could have a broadside weight per minute equivalent or superior to the 9 16").

Therefore, if we want to use the Rodney as reference, I guess we have to multiply the 550 by 1,333 to get a more reliable figure (732 ordered to fire), and in absence of a sure 62% output reference, this would mean a total output for KGV on May 27 of around 46%.
BTW, this 732 match fairly well with my previous hypothesis that, if gun no.4 in Y turret was able to fire 49 actual shells, it could have misfired sometimes (x times) as all the guns do in a normal prolonged fire action, it was not firing (because wooded or Y was out of order) for 28 minutes, then the theoretical salvos number for KGV is something around or more than 49+28+x = more than 80/85 full salvos, 800/850 shots ordered to fire to which we have to subtract the ones when a turret was not bearing.....)

What do you think ? You are the expert here, and I can be making a big mistake, of course......

Bye, Alberto

[dunmunro]

Dunmunro wrote: "I based ~550 possible (100% output) for KGV on Rodney's 375 rnds fired @ 77% output. Neither ship fired at maximum salvo rate and during turns and periods of poor visibility."

Hi Duncan,
my fault I have not read carefully your previous posts. Thanks for confirming. However the 62% output is still an assumption, isn't it ? I have not found this figure in the actual GAR. The only sure number is 339 actual shots fired.

In any case, we should take into account also that, disregarding the intervals when the 2 ships did not fire at their maximum rate (turns, radar unavailability, etc), the theoretical rate of fire of the 14" Mk VII was much higher than the one of the 16" Mk I (2 rounds per minute vs 1,5 rounds per minute, theoretical of course.....this was one of the reasons why the RN considered that 12 or even just 10 14" guns could have a broadside weight per minute equivalent or superior to the 9 16").

Therefore, if we want to use the Rodney as reference, I guess we have to multiply the 550 by 1,33 to get a more reliable figure (731 ordered to fire), and in absence of a sure 62% output reference, this would mean a total output for KGV on May 27 of around 46%.
BTW, this 733 match exactly with my previous hypothesis that, if gun no.4 in Y turret fired 49 shells, it was not firing (because wooded or out of order) for 28 minutes, then the theoretical salvos number for KGV is something between 70 and 75 full salvos.....)

What do you think ? You are the expert here, and I can be making a big mistake, of course......

Bye, Alberto

The salvo rate wasn't a really a function of rate of fire, rather it had more to do with visibility, the prevailing seastate and the need to be able to clearly identify own salvos. Theoretically Rodney could have fired at 3 salvos per minute but she only did that twice during the entire engagement and her overall salvo rate was about 1.3 salvos per minute. Output is based upon rounds fired divided into rounds "requested" not the number of rounds that the ship could fire at it's maximum rate of fire. None of the ships at Denmark Strait came close to matching their theoretical rate of fire. If KGV and Rodney fired with very short intervals between salvos it would have become almost impossible to decide which shell splashes came from which firing ship.

The RN considered that 10 or 12 guns would fire more guns per salvo and would have a higher hit rate over a given length of time than a ship with fewer, but heavier guns.

[Alberto Virtuani]

Dunmunro wrote:" Theoretically Rodney could have fired at 3 salvos per minute but she only did that twice during the entire engagement and her overall salvo rate was about 1.3 salvos per minute. Output is based upon rounds fired divided into rounds "requested" not the number of rounds that the ship could fire at it's maximum rate of fire."

Hi Duncan,
yes, you are right, and I'm calculating output in this way. However if we take as reference Rodney because we don't have the exact number of "requested" shots for KGV, then we should consider that rate of fire between the 2 ships was quite different.

No ship can fire in action at her max rat of fire for evident reasons : however if a ship has guns with a RoF slower by design , then this is affecting also the battle condition by almost the same amount......

As you say, Rodney salvo rate was 1,3 salvos per minute. KGV was probably able to fire almost 1 salvo per minute, as PoW actually did at DS, until her turn..... As you see the ratio is 1,33 difference between the 2 ships, exactly as the theoretical RoF would suggest.

Bye, Alberto

[Steve Crandell]

As you say, Rodney salvo rate was 1,3 salvos per minute. KGV was probably able to fire 1 salvo per minute, as PoW actually did on May 24, until her turn..... As you see the ratio is 1,33 difference between the 2 ships, exactly as the theoretical RoF would suggest.

Bye, Alberto

Um ... no. Rodney was firing faster than KGV according to your statement. KGV actually had a theoretical rate of 4 half salvos per minute, but only achieved 1.

[Alberto Virtuani]

@Steve Crandell,
thanks, you are absolutely right, my mistake, I mixed up Rodney 1,3 ( referred, I guess, to semi-salvos per minute, as the theoretical 3 salvo per minute cannot be full salvos as each gun could only fire at its best each 40 seconds) with KGV full salvos, of course....

Still my reasoning is valid: KGV had higher rate of fire that Rodney and this should be taken into account when making our assumptions.

Why do you say KGV achieved 1 semi-salvo per minute ? The "green" PoW achieved almost 2 semi-salvo per minute at DS and I assume KGV could do at least in a similar way.....

Bye, Alberto