Range and Penetration Table for the 38 cm SK C/34

[Thorsten Wahl]

It seems there are some misreadings from the chart entered into the penetration table

speed differences SK 38 c/34 e

Unbenannt.JPG (19.78 KiB) Viewed 2882 times

attached you can see a samplechart with differences from every kilometer to the next "Striking velocity" this chart should bee smoth, but there are some "edges" so you could check and maybe correct if you want

The same "problem" exists with the armour pentration data.

Then you should rename "sweep zone" to "danger space" according to english terminology

50% ige Längenstreuung called the range around the mean point of impact in wich 50% of shots land (within gaussian distribution) at 20.000 m - 110 m (50% ige Längenstreung ) out of a 4 gun salvo 2 shots land normally in the area between 19.945 and 20.055 m and the other 2 shoots outside within gaussian distribution

IMHO the facehard data does not fit correctly the penetration chart given in the gkdos, even the penetration data generated by facehard intersects the data from the chart at around 21 km. It seems the original chart is something steeper, but i dont have a high resolution chart to check this to "death".

But i also know the gkdos charts were created by using the best fitting curve ruler to several points on the paper.

[Thorsten Wahl]

).. out of a 4 gun salvo 2 shots land normally in the area between 19.945 and 20.055 m and the other 2 shoots outside within gaussian distribution
.

small correction not 4 shot salvo but 4 single shots

according to Bismarcks AVKS tests no salvo test were made, to identify salvo spreads, because lack of time at the testing period

[José M. Rico]

Hello Thorsten,

It seems there are some misreadings from the chart entered into the penetration table

attached you can see a samplechart with differences from every kilometer to the next "Striking velocity" this chart should bee smoth, but there are some "edges" so you could check and maybe correct if you want

The same "problem" exists with the armour pentration data.

I'm not sure I understand you chart correctly. The "X" axis is for Km. what does the "Y" axis stand for?

The striking velocity decreases as the distance increases up until 32,000 meters, which is the point in which the acceleration due to gravity begins to be greater than the deceleration due to air resistance. After that, the striking velocity increases again.

Of course, the original 100/40 g.Kdos chart is very smooth.

Then you should rename "sweep zone" to "danger space" according to english terminology

Yes, Ulrich translated it as "sweep zone" which is more a literal translation I guess.

50% ige Längenstreuung called the range around the mean point of impact in wich 50% of shots land (within gaussian distribution) at 20.000 m - 110 m (50% ige Längenstreung ) out of a 4 gun salvo 2 shots land normally in the area between 19.945 and 20.055 m and the other 2 shoots outside within gaussian distribution

Thanks! We were wondering what actually that meant for a long time.

[tommy303]

you should rename "sweep zone" to "danger space" according to english terminology

....or "beaten zone" which was used extensively in 19th century English for the same concept.

[Thorsten Wahl]

appended a Table with the Fall of Speed
The problems of difference I meant were on kilometres 4, 10, 13, 14, 20, 22 km

this sequence is also expected to be smoth in general

If you create a similar sequence from the pentration data you can see the same problem

[Thorsten Wahl]

I forgot the upload

Differences SK38 Impactspeed.JPG (18.6 KiB) Viewed 2683 times

[Bill Jurens]

I find Mr. Wahl's graph, posted Wed Oct 28, 2009 7:38 pm , most interesting, but cannot comment upon it as I can't quite understand how it was created. Could Mr. Wahl give more details on exactly exactly how this chart was derived, please, and can he confirm the labels for the ordinate and abscissa?

Thanks in advance...

Bill Jurens

[hammy]

Gentlemen ; RE the explanation regarding the Neue Art types of armour - could you supplement this with a post explaining the actual process involved please ?
I know you make your armour plate in forging rollers and then lay it flat on a bogey trolley before spreading the carbon on top (charcoal?) and then trundle the thing inside the big oven , lower the drop door , turn the heat on and leave to bake for a week or two so the carbon is "adsorbed" into the face of the steel , I then assumed you turned off the heat and allowed the thing to cool slowly so as to leave you with a "soft" untempered back , but a hard , carbonised face .
And then cleaned it before sending it through to the Armour erection floor workshop for trial assembly/final fettling , before it goes to the hull .
Do you use water spray to rapid-cool and help temper the plate face as well ?
The process I know dates from about 1910 era , can anyone give us the manufacturing process for these Neue Art types that enabled you to obtain plates with such consistently precise incremental degrees of hardness from face to rear face ?

[tommy303]

Hammy,

The following link should give you a good overview of the manufacturing processes.

http://www.eugeneleeslover.com/ARMOR-CHAPTER-XII-A.html

[Thorsten Wahl]

Its a simple analysis from the fall of striking velocity between every km to the next km, because of drag
from the
"Range and Penetration Table for the 38 cm SK C/34 Guns" statet here http://www.kbismarck.com/38cm.html

in the attachment you can find data, chart and also the labels

the fall should be steadily and smooth without Ecken und Kanten
Rashes in the graph indicates that there are misreadings
the misreadings are not huge but cause slight problems in deeper analysis

negative values at the end are showing the effect of gravity in reincreasing speed at higher angles of fall
seems it is impossible to post an spreadsheet
so I post an image

Differenzanalyse.JPG

(171.51 KiB) Not downloaded yet

[José M. Rico]

Oh, I see what you mean.
I will check it everything out again as soon as I have some time.

The curve is the one on the left under "Endgeschwindigkeit Ve"

[hammy]

Thanks tommy , thats an excellent resource

[Bill Jurens]

To Thorsten Wahl:

OK, I see what you are doing now. I am sure the discrepancies are due to slight 'errors' in reading the graph. They could be smoothed further using second or third differences as you have done. In that regard, one must remember that the original chart itself represents a theoretical construct rather than a set of actual measurements. When these tables and charts were constructed, about the only variables that could be measured directly were range to impact (itself difficult to determine due to unavoidable dispersion errors) and time of flight. Usually the procedure was to force a smooth line through a scatter plot of range vs angle of departure, then adjust the ballistic equations until they gave similar results. Once range vs angle of departure was determined, the other variables, e.g. angle of fall and striking velocity were assumed to vary in a similar manner. Usually, time of flight and range could not be made to match exactly; this was because the equations, really only good for 2 Degree of Freedom trajectories and incapable of directly accounting for projectile yaw, etc., were only approximate. The results of all the test firings, etc., were plotted to large scale on a big graph, and smoothed using flexible battens similar to those then used in shipbuilding on the mold loft floor. After the master graph was completed, figures were picked off manually and inserted into range tables. This process also graphically achieved the tranformation of the original data set, which used angle of departure as an independent variable to the range table matrix, which used range as an independent variable.

Bill Jurens.

[dunmunro]

Here's a set of very comprehensive penetration tables:

http://www.navweaps.com/index_nathan/Pe ... _index.htm

[Thorsten Wahl]

Here's a set of very comprehensive penetration tables:

http://www.navweaps.com/index_nathan/Pe ... _index.htm

According to the data from above I made a small grafics
the result looks very interesting
the SK 38 gun is partly better in belt penetration than the US 16/50 gun.
and the British 14/45 gun is completly better in belt penetration than the US 16/45 gun

the original penetration data for the SK 38 from the gkdos-chart are additional around 3,5% better than the data from facehard