Jasper, Schmalenbach and 6 salvos...

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Alberto Virtuani
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Alberto Virtuani »

Hi Mr.Cag,
my 2 cents opinion on what you proposed above:
British witnesses clearly saw too few salvo falling around Hood, possibly the smoke of the deck fire was hiding the others..... Even assuming Vollsalve are fired (and AVKS exclude this possibility, as logical, except under special situations). there are too many witnesses who saw just 1,2,3 or max 4 splashes to have a possibility that Bismarck and/or PG were firing Vollsalve.

Also, and mostly, a fire for effect of only 3 Vollsalve (after the gabelgruppe, to respect the 40 shots ordered) without waiting for spotting and corrections, would imply just 1.5 minutes maximum after the deck hit for Hood explosion (5:58:xx), that we have already discussed at length in another thread.
It would also imply an enormous amount of shells expended during the whole battle (in this scenario we have at least 5 minutes fire on PoW with BS on steady course with other 60 shots ordered as minimum until 6:03 (in full salvo mode it would be even a greater number) while we know 93 were actually fired (vs 104, 108 or probably 112 ordered). Please remember, we have at least 48 shots (proved by PG photos or film) fired after 6:03...... :think:

A last option (that I have tried to put on paper in an alternative salvo chart) is that Bismack fired full salvos (or shortly separated A+B, C+D "doubles") spotting the fall of shots and correcting the firing parameters, but this basically changes nothing in terms of elapsed time (2.5 minutes after the deck hit), while it contradicts the British witnesses count of splashes (remember also Rowell accounting for a relatively high number of salvos fired in a zig-zag ladder mode after the deck hit...).

In the absence of any alternative official document, IMO the AVKS is the only reference we should use.


Bye, Alberto
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Cag »

Hi All

Hi Alberto thanks, so the observed British salvo count must be wrong in the Boards second inquiry?

Would that mean the British should have seen around 19-20 salvo group splashes from both German ships from open fire to Prinz Eugen switch and Hood exploding?

Thanks
Best wishes
Cag.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Alberto Virtuani »

Cag wrote: "Would that mean the British should have seen around 19-20 salvo group splashes from both German ships from open fire to Prinz Eugen switch and Hood exploding?"
Hi Mr.Cag,
no, just that they were unable to see all the salvos and just "counted" what they saw. In the same way, many witnesses saw very few salvos fired from Hood while Schmalenbach counted 10 of them......

What we know for sure is that the PG fired 5 salvos to Hood before 5:57:xx (Jasper), while British witnesses saw 1 or 2 salvos with HE splashes maximum......Therefore no surprise (for me) that Bismarck fired 9 heavy salvos instead of the 5 "counted" by witnesses.


Bye, Alberto
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Herr Nilsson »

Alberto Virtuani wrote:I also trust the excellent book of the Baron who did NOT copy from randomly picked documents (e.g. he was clever enough NOT to copy the blatantly incorrect Tovey point 17 and 19, regarding PoW retreat time and SF / NF distance, while other authors slavishly did....). He was there, he was the 3rd G.O. and he did hear Schneider repeated requests to open fire.
Alberto Virtuani wrote:...., if you accuse the Baron (BS 3rd GO) to have fully invented the long account of open fire (and the words he heard himself through the BS gunnery network),...
I'm still looking for the term "semi salvo" in regard of Bismarck's firing against Hood. It appears it has escaped my notice.
Regards

Marc

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Re: Jasper, Schmalenbach and 6 salvos...

Post by wadinga »

Hello Dave,

You are the goto man in all matters of German radar, but how did a "hard wired solution" cope with sea clutter, spurious returns etc? There must have been human filtering, and possibly rejection, before numbers went in to the FC solution.

If this radar indication had given an accurate "rate of change of distance" which as Alberto has pointed out would have been very high, and therefore prone to error, then rapid fire and hitting could be maintained, but if the wrong rate were being applied, then the spotter would have to realise the forest of splashes were happening in the wrong place.

The Duke of Wellington said
The history of a battle, is not unlike the history of a ball. Some individuals may recollect all the little events of which the great result is the battle won or lost, but no individual can recollect the order in which, or the exact moment at which, they occurred, which makes all the difference as to their value or importance.
How true :clap: :clap: :clap:
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Re: Jasper, Schmalenbach and 6 salvos...

Post by dunmunro »

One of the things that stands out is the poor accuracy of PE's 20cm gunfire, considering the flat trajecory of these weapons and the fact that PE had radar ranging. At best PE obtained about 5 hits from 157 rnds fired. Most of these were fired against PoW at relatively close range.

The other thing that is puzzling is that Jasper states that PE attained a salvo rate of one per 27-28 seconds and that she fired 28 salvos under forward director control and further salvos using the after director and after turrets only. Taken literally this means that PE fired 28 salvos in 770 seconds (28 x 27.5seconds) or 12.88 minutes. If PE opened fire at exactly 0555 then her forward director was wooded at 0607:53. This calculation also support an open fire time for Bismarck of ~0553 since it seems to support PE opening fire at ~0554.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Alberto Virtuani »

Hi Duncan,
PG fore director was wooded at around 6:04:30 as per her battlemap, and apparently control was never passed back to the fore director.

In my salvo chart for PG, she opened fire at 5:55:20, fired 5 salvos at Hood (including 2 initial full salvos), switched fire to PoW at 5:57:45, fired 28 salvos at PoW (including one initial full salvo) from 5:58:15 till 6:04:45 and finally 20 salvos in aft control using only the aft turrets, ceasing fire at 6:09:10.

Everything matches with PG open fire after 5:55, as well as Bismarck.


Bye, Alberto
Last edited by Alberto Virtuani on Tue Feb 28, 2017 10:15 pm, edited 1 time in total.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Dave Saxton »

wadinga wrote:Hello Dave,

You are the goto man in all matters of German radar, but how did a "hard wired solution" cope with sea clutter, spurious returns etc? There must have been human filtering, and possibly rejection, before numbers went in to the FC solution.
The way the fine ranging system worked was that the selected target pip was moved to the zero mark at the center of the screen via a hand crank. As long as the pip was held on the zero mark at the center of the screen, the range was measured electronically. The electronically measured range was automatically transferred to the fire control computers below decks via selsyns. It was not phoned in by the radar operators or by a person reading the data off the indicators, or from reading off from the digital gauge that the range was also displayed on for a reference.

In the report documents of Hipper's radar operations during the Battle of Barents Sea, they reported that they had to phone in the data from the aft radar set to the computer room because the cable carrying the electronic data had a faulty connection right where it hooked up to the fire control computer. Note that it was standard operating procedure that range and bearing data from the radars for the selected target was directly inputted into the fire control computer. They were phoning it in only because the primary procedure wasn't working.

There was, nonetheless, a human element in the fine ranging system operator. In practice all the operator had to do was hold the the target pip on the zero mark with the hand crank. If he failed to notice that the pip was not exactly on the zero mark or if he was slow to make adjustment then this would introduce an error. At the time of Denmark Strait, the range accuracy of the radar was 40 meters and the fine ranging system worked in 50 meter steps.

According to the AVKS report for Bismarck, the AVKS had Siemens come in and install a parallel system (parallel to the data stream of the optical range data) for electronic transfer of radar range data. Data from the radar was automatically transferred directly to the fire control computer regardless of which system the gunnery officers were using. Previously on Bismarck it could only transfer optical or radar range data, but not both at the same time. The AVKS did this in part so that they could compare the two data sets during testing, but I suspect it also made it so recalcitrant gunnery offers would often be using radar ranging by default.

Did intermittent inputs from the optical data stream and/or over riding "corrections" throw things off?

There can be little question that Bismarck had the correct range, and rate, on Hood at the very beginning. One salvo just over and one just short firing the initial bracket, followed by salvos producing hits, proves this.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by dunmunro »

Alberto Virtuani wrote:Hi Duncan,
PG fore director was wooded at around 6:04:30 as per her battlemap, and apparently control was never passed back to the fore director.

In my salvo chart for PG, she opened fire at 5:55:20, fired 5 salvos at Hood (including 2 initial full salvos), switched fire to PoW at 5:57:45, fired 28 salvos at PoW (including one initial full salvo) from 5:58:15 till 6:04:45 and finally 20 salvos in aft control using only the aft turrets, ceasing fire at 6:09:10.

Everything matches with PG open fire after 5:55, as well as Bismarck.


Bye, Alberto
PE's battlemap doesn't show her forward director wooded at 604:30.

I'm not sure it was possible for PE to have fired 20 salvos in ~4:25 (265 seconds). In any event Jasper clearly states a salvo rate of 27-28 seconds per salvo. You have PE firing 33 salvos at Hood and PoW ( 33x 27.5 = 15:07) and then 20 additional salvos after that...clearly somethings wrong here.

Jasper states that PE turned hard toward him at about the 8th salvo. If Jasper is meaning that he fired 8 salvos prior to this, then it means that he opened fire on PoW almost 4 minutes prior to PoW's turn. This implies changing target to PoW at ~0554-0557 (depending on when Hood blew up), and indeed PE's battle map has the change target to PoW order timed at 0555.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Alberto Virtuani »

Dunmunro wrote: "PE's battlemap doesn't show her forward director wooded at 604:30."
Hi Duncan, of it does. PG was ahead of Bismarck and her fore turrets were wooded at 6:04:xx. Jasper accoun tis clear enough.
PG_first_turn.jpg
PG_first_turn.jpg (4.44 KiB) Viewed 1288 times
Regarding the salvos, of course the RoF is related to shots per minute per gun, while the count of salvo is basically a count of semi-salvos (exception are the 3 Vollsalve). We have discussed already this aspect in detail in the past.....

The 27/28 secs RoF is perfectly respected by my timing above and by my proposed salvo chart. It's clearly impossible that PG fired ONLY 28 semi-salvos from switch fire (5:58:15) and 6:07:30, as this would NOT allow the aft director to fire enough salvos until 6:09:10 (cease fire) to reach the total of 184 ordered shots (157 fired shells).


Bye, Alberto
Last edited by Alberto Virtuani on Wed Mar 01, 2017 8:40 am, edited 1 time in total.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by dunmunro »

Alberto Virtuani wrote:
Dunmunro wrote: "PE's battlemap doesn't show her forward director wooded at 604:30."
Hi Duncan, of it does. PG was ahead of Bismarck and her fore turrets were wooded at 6:04:xx. Jasper accoun tis clear enough.
PG_first_turn.jpg
Regarding the salvos, of course the RoF is related to shots per minute per gun, while the count of salvo is basically a count of semi-salvos (exception are the 3 Vollsalve). We have discussed already this aspect in detail in the past.....

The 27/28 secs RoF is perfectly respected by my timing above and by my proposed salvo chart. It's clearly impossible that PG fired ONLY 28 semi-salvos from switch fire (5:58:15) and 6:07:30, as this would NOT allow the aft director to fire enough salvos until 6:09:10 (cease fire) to reach the total of 157 ordered shots.


Bye, Alberto
No the map does not show the forward director wooded until ~0607. This is easy to see on the battlemap. At 0604:30 PE's forward turrets are firing ~35degs abaft the beam but their maximum traverse was 55 degrees abaft the beam and this didn't occur until ~0607.

Jasper states the time per salvo.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Cag »

Hi All

May I say thank you Mr Saxon for that information it is a great help. I guess this information from the radar would be used in conjunction with the Vorzündwerk method of firing where the turret is moved through the firing bearing?

Thanks anyway for that, the wealth of experience and knowledge of experts here is excellent.

Best wishes
Cag.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Alberto Virtuani »

Hi Duncan,
we have already discussed the salvo count in a very long thread, pag.25 to 29 (viewtopic.php?f=1&t=5752&start=360). The salvos are counted as full or semi in the same way: one salvo is a salvo (2, 4 or 8 guns) fired at a certain time.
Jasper stated a RoF and RoF is clearly related to shot per minute per gun. If it was a (mostly semi-)salvo rate, then in 14 minutes, PG would have been able to fire ONLY 15 full salvos (thus 120 ordered shots) instead of 184, NOT counting for initial ranging salvos with flight time of 36+ secs, turns, switch fire delay, etc.....

Re. A-arcs, I think it was the first turn that wooded the fore turrets (it's discussed in the same thread I posted above....how tiring to have to repeat each time the same considerations.... :stop: ), but as I admit this is my interpretation, please try to build an alternative COMPLETE salvo chart for PG, respecting the max RoF of 27 secs and Jasper GAR.......

Here is my complete salvo chart for PG (based on Antonio's battlemap/distances, but differing from his one regarding PG aft salvos, respecting Jasper GAR, RoF and output loss: of course the turret failures are just an educated guess in most cases....):
PG_Salvos_Hood.jpg
PG_Salvos_Hood.jpg (32.99 KiB) Viewed 1271 times
PG_Salvos_PoW_Central-1-1.jpg
PG_Salvos_PoW_Central-1-1.jpg (123.68 KiB) Viewed 1254 times
PG_Salvos_PoW_Aft-1-1.jpg
PG_Salvos_PoW_Aft-1-1.jpg (82.21 KiB) Viewed 1254 times
I had to separate in 3 parts and to remove some (calculation and distances) columns to fit the max size allowed by the forum.


Bye, Alberto
Last edited by Alberto Virtuani on Wed Mar 01, 2017 12:03 pm, edited 6 times in total.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by alecsandros »

Hello Alberto,
I've been looking at other instances of German Hipper class cruisers firing their guns in battles. Contrary to what I expected to find, it appears that Battle of Denmark Strait is an exception in terms of actual rate of fire (effective rounds actualy fired per unit of time), the other engagements having a smaller rate of fire then Denmark Strait did.

Examples:
Koop in "Cruisers of Admiral Hipper class" mention the same Prinz Eugen in Fev 1942 (Channel Dash) as consuming 108 x 203mm shells in 14 minutes (firing against British destroyers that were attempting torpedo attacks). It's not clear to me if firing was continous per given interval, my impression is that it wasn't.

Same source mentions Hipper in Fev 1941 consuming 235x203mm and 760x105mm against unescorted convoy SLS64. Duration of firing: 68 minutes.
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Re: Jasper, Schmalenbach and 6 salvos...

Post by Alberto Virtuani »

Hi Alec,
very interesting instances, thanks.

I'm not really surprised by the "practical" RoF of PG and BS (despite the uneasy geometry/range decrease rate), while I'm impressed by the high RoF of PoW, despite the "common" critics to her gunnery....

Overall, the battle of DS was an exceptionally rapid encounter, with a remarkable RoF and absolutely fast development/maneuvers..... :think:


Bye, Alberto
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