KGV Class Battleships

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Re: KGV class

Postby alecsandros » Fri May 07, 2010 6:50 pm

dunmunro wrote: What you are saying is so far from reality, that it represents a completely false impression of the RN FC.

See above
These are the 5"/38 FC computers and the Mk 1A was the post war variant of the Mk1. Radar integration, for example, was not achieved, until well into 1942 and in May 1941, the USN did not have any dedicated FC radars, and when they did achieve them, they were based upon UK technology.

Mark I was the computer used by American North Carolina, South Dakota and Iowa classes. The Iowa's received the modified Mark I A after the war.

During their action with Renown, in a heavy sea state, S&G both suffered from numerous turret and FC failures.

Agreed.

Massachusetts was carrying out a bombardment mission, with very slow deliberate fire, under essentially calm conditions, and this is not comparable to a BB versus BB action in the open sea, in gale force winds. Massachusetts did suffer a turret jam on that day. You cannot compare short BB versus BB actions, under ideal conditions to lengthy engagements in heavy seas. All nations BB FC and ammo systems were complex and likely to suffer a substantial loss of output under prolonged combat conditions, especially in heavy weather.

Yes, Mass fired in good conditions. However, for 2 time intervals at least, it's fire wasn't "very slow" at all.

The problem I was trying to adress concerns mainly the turret jams, and secondly the FC system (as the first will cause instant fire output, while the second can be - albeit hardly - substituted by more traditional approaches). I didn't know Mass had a jamed turret that day. Was it during the action? And how long did it last to correct it?

What about KGV's lower shells output (339 coming from 10 guns) than Rodney's? (380 shells coming from 9 guns)
And what about PoW turret jams in relatively good sea, while at Denamrk Strait?

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Re: KGV class

Postby dunmunro » Fri May 07, 2010 8:20 pm

Yes, it was a modern FC computer.
What I said was that the AMERICAN FC SYSTEM was superior to any other during the war. "Coupled with the stable element, servos, inegrated radar + director solution, it was superior to any other fire control system"

I have yet to see another computer which takes into account Earth rotation and gravitational variations into account, automaticaly delivers the solution to the turrets, which also, automaticaly train and elevate their guns based on that specific solution, which is modified in a continous, automated stream, by the Mark I computer.



KGV class: the firing solution was calculated and the infos sent to the turrets by phone/interphone


The above statement is incorrect, the gun orders were sent directly from the AFCT to the range/bearing receivers in the turrets . As I've pointed out, Washington also used a Follow the Pointer system at Guadalcanal, not RPC, so in late 1942 there was really no difference between RN and USN FC. All RN radar systems with a Precision Ranging Panel could send radar range data directly to the AFCT/HACS computer range inputs, and such systems were in use in late 1940/early 1941. The USN had considerable difficulty in implementing RPC, especially in the prewar/early war period.
The Mk 1 computer was used for the 5"/38 guns, and the Ford Mk8 Rangekeeper was used for controlling the 16" guns.

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Re: KGV class

Postby dunmunro » Fri May 07, 2010 8:46 pm

Yes, Mass fired in good conditions. However, for 2 time intervals at least, it's fire wasn't "very slow" at all.

The problem I was trying to adress concerns mainly the turret jams, and secondly the FC system (as the first will cause instant fire output, while the second can be - albeit hardly - substituted by more traditional approaches). I didn't know Mass had a jamed turret that day. Was it during the action? And how long did it last to correct it?

What about KGV's lower shells output (339 coming from 10 guns) than Rodney's? (380 shells coming from 9 guns)
And what about PoW turret jams in relatively good sea, while at Denamrk Strait?


Massachusetts was fighting in late 1942, and by that time the problems with the KGV class turrets had been rectified. Given the same conditions, a KGV class BB would probably have matched Massachusetts output. IIRC one turret was out of action for a ~15-30mins due to a dropped shell on the turret shell ring.

Both PoW and KGV had been rushed into service without a proper work up of the turrets under realistic conditions. As you know PoW still had civilian workers on board when she engaged Bismarck. After the experiences of the PoW and KGV, in the summer of 1941 both ships and all subsequent ships received extensive modifications to the turrets to reduce the likelihood of jams in the ammo feed system.

If KGV and Rodney had fought the battle side by side, in close order, then I doubt there would have been much difference in their respective outputs, especially as KGV suffered from having Rodney's gun smoke obscuring her visibility, during some phases of the battle.

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Re: KGV class

Postby alecsandros » Sat May 08, 2010 6:07 pm

dunmunro wrote:The above statement is incorrect, the gun orders were sent directly from the AFCT to the range/bearing receivers in the turrets.

The firing solution, e.g. the training of the turret and elevation of the guns were manualy inputed.

As I've pointed out, Washington also used a Follow the Pointer system at Guadalcanal, not RPC, so in late 1942 there was really no difference between RN and USN FC.

Yes, but the discussion, at least from my perspective, concerns the performance of the KGV class throughout the war. DoY's results at North Cape weren't the best possible, IMO. They could have been, it they would have incorporated the latest technology.

The Mk 1 computer was used for the 5"/38 guns, and the Ford Mk8 Rangekeeper was used for controlling the 16" guns.

No.
Mark 1, developed by Ford, was a mechanical computer which generated firing solutions for all US navy ships, including battleships. The Mark 8 was developed by Bell, and it was never used on a ship. It may have served as an inspiration, though, for the Mark IA.
http://en.wikipedia.org/wiki/Mark_8,_Fi ... l_Computer

I've counted 16 independent variables which were managed simultaneously and instantaneously by the Mark I. Including gun wear, projectile shape, diameter and rate of spin, [internal ballistics] and atmospheric pressure, temperature of the powder charges, magnus and coriolis effects [external ballistics].

It is of note that the IJN guns performed dubiously during Leyte (the attack over the carriers) while the US destroyers managed a significant number of hits over several ships. This may be due to the fire control system incorporated into the US warships.

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Re: KGV class

Postby dunmunro » Sat May 08, 2010 7:55 pm

"By the time of World War II most main battery fire
control was done by Range Keepers Mark 8 in Directors
Mark 34, mainly for cruisers, and Directors Mark 38, for
cruisers and battleships.
” The Ford range keepers were
superseded by the Ford Computer Mark 1 in the Gun
Director Mark 37. This director was first tested in 1939 and
it quickly became the standard dual-purpose director in
World War II, although many Range Keepers Mark 10 in
Directors Mark 33 also were built and used. The Bureau of
Ordnance considered the Computer Mark 1 to be “enormously
successful.“” The system included transmission of
data to and from the computer below decks by means of
synchros. Designed originally for the 5-inch/38 guns, it was
soon modified by Ford Instrument Co. for a number of other
guns and ammunition types as well."


http://web.mit.edu/STS.035/www/PDFs/Newell.pdf

The Ford Mk 1 computer was a development of the Mk 1O Range keeper, and was the first Ford FC computer to be actually named as a computer rather than as a range keeper, and the Mk 1 computer was used primarily with the MK 37 GFCS, where the Mk 10 Rangekeeper was used primarily with the Mk 33 director system.

The Bell labs Mk 8 Fire Control computer was never used in combat and remained as an experimental, developmental unit.

When discussing Ford Instruments FC equipment, you have to be very carful to distinguish between range Keepers and computers.
Last edited by dunmunro on Sat May 08, 2010 8:41 pm, edited 1 time in total.

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Re: KGV class

Postby dunmunro » Sat May 08, 2010 8:18 pm

alecsandros wrote:

I've counted 16 independent variables which were managed simultaneously and instantaneously by the Mark I. Including gun wear, projectile shape, diameter and rate of spin, [internal ballistics] and atmospheric pressure, temperature of the powder charges, magnus and coriolis effects [external ballistics].


The AFCT also included all these variables in its calculations, for example:

"The drift deflection also includes a component due to latitude of the ship as the Coreolis Force due to the rotation of the earth produces a similar effect to the drift and is represented by an alteration in the drift constant..."

http://www.it.usyd.edu.au/research/tr/tr223.pdf

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Re: KGV class

Postby alecsandros » Sat May 08, 2010 8:48 pm

dunmunro wrote: When discussing Ford Instruments FC equipment, you have to be very carful to distinguish between range Keepers and computers.


I should distinguish between them? You just said Mark I was used only for 5" inch guns!

As for AFCT, it did not have the same coplexity as the mark I:

"... No bearing deflections for wind are computed by the Fire control box and these must be allowed for in the spotting".
The more advanced AFCT is not presented as having inputs from the pitot tube or similar device which records wind speed.

Ford Mark I automaticaly received inputs for wind speed and direction.

Also, I see nothing about gun wear, poweder charge temperature, magnus effect or gravitational pull.

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Re: KGV class

Postby dunmunro » Sat May 08, 2010 9:33 pm

alecsandros wrote:
dunmunro wrote: When discussing Ford Instruments FC equipment, you have to be very carful to distinguish between range Keepers and computers.


I should distinguish between them? You just said Mark I was used only for 5" inch guns!

As for AFCT, it did not have the same coplexity as the mark I:

"... No bearing deflections for wind are computed by the Fire control box and these must be allowed for in the spotting".
The more advanced AFCT is not presented as having inputs from the pitot tube or similar device which records wind speed.

Ford Mark I automaticaly received inputs for wind speed and direction.

Also, I see nothing about gun wear, poweder charge temperature, magnus effect or gravitational pull.


~95% of all Mk 1 computers were used as primary control of 5" guns. The only exceptions were a handful of Mk1A units modified to control the 6"/47 and 8"/50 DP guns developed by the USN after WW2, while about two dozen or so units were used by the RN for 4.5" and 5.25" guns, post war.

AFCT = Admiralty Fire Control Table. This was the most advanced FC computer used by the RN during WW2.
AFCC = Admiralty Fire Control Clock. This was a simplified AFCT. The manual for this unit can be found here: http://www.hnsa.org/doc/afcc/index.htm
AFCB = Admiralty Fire Control Box. This was a very basic FC computer, designed for smaller vessels such as frigates where long range fire was not likely or as a back-up unit for turret local control, on larger ships.

The AFCT and AFCC correct for every factor which is likely to generate sufficient errors for it to be taken into account, including gun wear, powder temp, and the magnus effect (drift). The AFCT and AFCC receives radar ranges automatically from the radar RTU.

Here is the input table for the MK1:

Image
http://www.hnsa.org/doc/firecontrol/partg.htm
and as you can see wind direction and speed are entered manually by the computer operators, just like in the AFCT/AFCC.

Here's the input table for a Mk8 rangekeeper:

Image
http://www.hnsa.org/doc/firecontrol/partf.htm

again, very little difference between the Mk8 and the AFCT and AFCC.

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Re: KGV class

Postby Bgile » Sat May 08, 2010 11:46 pm

US FC computers didn't compute target course and speed?

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Re: KGV class

Postby tommy303 » Sun May 09, 2010 3:27 am

US FC computers didn't compute target course and speed?


I am not exactly sure what you mean Steve, but the US FC computers and rangekeepers both had inputs for target course and speed as part of the necessary data required for horizontal fire solution; the Mk1 Ford Computers also had inputs for change of altitude for determining slant range when engaging aircraft.

Also, I see nothing about gun wear, poweder charge temperature, magnus effect or gravitational pull.


alecsandros: gun wear was built into the rangekeepers and fire control tables and did not require a manual input, except to switch between cams when reduced charges were fired. This was part of the ballistic element of the rangekeepers and FC tables and operated through a set of cams and gears. New gun calculations and estimated rate of wear were provided by the gun makers and built into the tables and rangekeepers. Estimated wear was not generally linear and could, and would, change over time the more the gun was fired; generally the amount of wear increased rapidly the more the gun was fired, so it was necessary to measure the gun bores using a star gauge whenever a ship was in port after a major fire operation. This was normally done when a gun bore was thoroughly cleaned and serviced to remove copper deposits and after lapping the bore to remove high points that might have developed as the liner stretched. Once the bore had been thoroughly cleaned and gauged, new calculations were made for the expected wear of the liners from that point on, and new cams would then be machined and installed in the rangekeepers and fire control tables.

Powder temperatures were incorporated into the fire control equipment as a constant measured in the air conditioned magazines.

Magnus effect was a constant calculation built into the AFCT which could be modified by inputs for wind direction and wind velocity. Magnus effect was primarily a matter of how much a projectile yaws in flight, as virtually all spin stabilized projectiles apart from round balls will--i.e., the nose never quite matches the projected trajectory. Wind direction and speed can effect the amount of yaw, and hence drag, causing the projectile to hit either higher or lower than intended. Provided the gunmakers used optimum rate of spin, velocity, and projectile configuration for their product, AFCT could adequately compensate with wind direction and velocity inputs. Wind direction and velocity was also used in compensating for the amount of right or left drift caused by the direction of rotation imparted by the rifling and in which hemisphere the ship was operating at the time (Coriolis Effect was activated by a simple mechanical switch).

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Re: KGV class

Postby Bgile » Sun May 09, 2010 5:05 am

tommy303 wrote:
US FC computers didn't compute target course and speed?


I am not exactly sure what you mean Steve, but the US FC computers and rangekeepers both had inputs for target course and speed as part of the necessary data required for horizontal fire solution; the Mk1 Ford Computers also had inputs for change of altitude for determining slant range when engaging aircraft.



I think that they took bearing and range input and after several minutes generated a calculated course and speed for the target. The director was, I believe, servo controlled and would continue to track the target without any input from the director pointer. He could override it, and that would cause the computer to recalculate a new course and speed based on the director bearing input and the radar range.

Truthfully I'm not sure how much of this is my gunnery knowledge and how much is running a submarine analog FC computer. Given your own course and speed and the target's bearing rate and shaft rpm, you can get a good picture of it's course and speed, especially after own ship makes a turn and settles on a new course for a few min. With two course legs you can get a good target course speed and range solution. But that's OT.

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Re: KGV class

Postby alecsandros » Sun May 09, 2010 8:21 am

The goal of any FC system is to provide real-time firing solutions.
The firing solution ultimately boils down to 2 command categories: gun elevation (different between the guns mounted higher on the barbettes than the ones situated more closely to the deck) and turret training (again, different between the turrets due to the paralax problem, not to mention if they are to engage multiple targets)

Given the multitude of variables taken into accoutn while calculating the FS, it is only natural that the computations would be done automaticaly, by specialised machines. Considering possible rapid variables change, the output from the computaion machines to the firing devices (turrets/guns) should also be done automaticaly, thus sparing time and improving accuracy.

After all, the slower the time between basic observation (range, bearing, wind speed, etc) and final (correct) gun elevation and turret training disposition, the faster the shells can be against to the target. I hope this is in agreement with everyone around here.

Following this stream of thought, it is only logical that the more automated the flow of information between computation machine (AFCT, Mark I computer, etc) and turrets/guns, the faster and more accurate the orientation of the turrets and the elevation of the guns is.

Consequently, integrated servo-mechanisms, capable of training the turrets and elevating the guns automaticaly, based upon the firing solution provided by the computation machine provide faster and more accurate overall response.

Historicaly, the USN:
- implemented servos for both training and elevation on all ships after 1942.
the KGM:
- implemented servos for gun elevation on Bismarck class, heavy cruisers Prinz Eugen and Hipper, from 1940-1941.
the RN, IJN:
- did not implement servos for either ones.

Taking this into consideration, I can't help but wonder why did 2 of the strongest navies in the world fail to implement these solutions.

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Re: KGV class

Postby tommy303 » Sun May 09, 2010 6:57 pm

Consequently, integrated servo-mechanisms, capable of training the turrets and elevating the guns automaticaly, based upon the firing solution provided by the computation machine provide faster and more accurate overall response.


RPC was a useful tool in that it automated keeping the guns on target for elevation and (in the USN, train as well), thus eliminating the human element at the gun mountings, at least within the capabilities of the system. If the ship is on a steady course or maneuvering slowly, the system could keep up with the fire control solutions as they were generated. It certainly helped relieve the gun layers and mount pointers of a great deal of work. Essentially, these two would have only to oversee the train and elevation when the mount was under RPC, and apply fine corrections as needed. This was actually more often than one would think in the USN system as the synchros could over or under compensate for course and range changes and for pitch and roll under certain conditions. The German thyratron system was a bit more precise and with less lag time, which is why they chose to use it only for elevation: since they used a tight bracket system for ranging, they probably made the right decision in their RPC system, but one has to admit that it would have been useful to have it for train as well. Post war the USN investigated the German system when they examined the Prinz Eugen and found it had some advantages, leading to adoption of thyratrons in the late 40s and 50s.

RPC was not necessarily faster nor more accurate than follow the pointer, but it was a lot less work. In follow the pointer with the latest systems, the British layers and pointers could keep the guns on target as rapidly and as smoothly as RPC, provided their training and experience levels were of a high order. If you had relatively untrained or inexperienced crews, RPC was much better.

The main reason that RPC was not used for the turrets and guns in most navies, apart from the German and US navies, was most of the world utilized DC current instead of AC for domestic and military power supplies. DC can be used in simple modes, as was the case with the British H and P sights, but it could not provide the power output necessary for managing guns and turrets. In the USA, Tesla's AC had almost completely replaced DC in most power applications, and so the US had rather more experience with it than most.

Steve: I see what you are talking about now--mostly a matter of data flow within the system. I know in the German Schusswertrechner, enemy course and speed were fed into the A component of the FC computer which calculated it as one part of the rate of change formula, and with inclination from the director pointer and own course and speed from the pitot log, combined to form a flow of prediction data for relative range and rate of change. This was then taken up by the ballistic component which used the predictions from the A Component to generate continuous true gun range . I am sure in the USN computers and rangekeepers, it was handled in much the same manner. Both the German and USN used a closed loop data flow system whereby generated data was directed to the director whose crews would check for errors in train and elevation and apply corrections. However, there was a diffence in those old analog systems compared to the more modern FC systems.

In modern ones, a step by step calculation is used to generate the solution. When a correction or change is required to adjust the solution, it forces the computer to start over again and recalculate the solution. In analog, once it was running, corrections could be applied without stopping the data flow. It was rather like an old scale which uses a spring and hook to weigh something, with a pointer to show the weight. You could hang a bucket of water on the scale and it would show the weight. If you poke holes in the bucket, it will continue to show the weight as it changes when water runs out. On a digital scale, change the weight and the scale must recalculate everything.

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Re: KGV class

Postby lwd » Mon May 10, 2010 2:59 pm

tommy303 wrote: ... Post war the USN investigated the German system when they examined the Prinz Eugen and found it had some advantages, leading to adoption of thyratrons in the late 40s and 50s.....

This article addresses this to at least some extent:
http://www.navweaps.com/index_tech/tech-013.htm
The German system used "magnetic amplifiers" which were also a kind of AC electric transformer, but did not use any vacuum tubes to amplify the leverage (voltage) of the control circuits--they acted more like the nested coils in the ignition system of automobiles. They seem to have been quite satisfactory and U.S. ordnance designers studied them carefully during and after WWII. In some functions, the German-developed magnetic amplifiers turned out to be best and the U.S. Navy adopted them after WWII, but synchroes seem to have been best for raw power output for controlling weapon train and elevation machinery and are still used in many cases by many navies,

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SoDak at North Cape?

Postby dunmunro » Thu May 20, 2010 9:55 am

I wouldn't even want to think about it:

http://www.researcheratlarge.com/Ships/ ... amage.html


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