7,5 cm Kwk/StuK/Pak 40 Firing Table Data

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Yoozername
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#376

Post by Yoozername » 29 Mar 2018, 07:55

Nick the Noodle wrote:
Mobius wrote:I also agree that some of the 'maths' don't get it right. That is why I collect so much data. I average them all together to find a consensus.
No knock on Bovington but they did get the MV of the 75mm/L43 wrong.
The Mark V round listed, I suspect is the Vickers HV 75mm, and an error in the original report. Just a gut feeling.
He has those 'Scientific-Gut' feelings to go along with his Advanced degrees.

{I have no idea what he is saying BTW...what 'Mark V' round????]

Richard Anderson
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#377

Post by Richard Anderson » 29 Mar 2018, 18:53

Yoozername wrote:
This is getting odd, but in fact APG was the Ordnance Department Museum in WWII.
His 'point' was that it wasn't taken very good care of, ergo,somehow it invalidates all the testing that was done that proves him to be a numbtard.

Was it not taken care of back then? Could it possibly matter? How many rusty tanks could they have outside in the elements in 1939???
Oh, I understand, but I lost track of his "point" a while ago and was just trying to clarify that historical datum. :D
Richard C. Anderson Jr.

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whelm
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#378

Post by whelm » 29 Mar 2018, 23:01

Ulater wrote: Strange thing about that is that as long as it is a cast armor, it fails to meet your imagined standard of 89 mm RHA protection, RHA that was a standard medium for testing, and offers better protection than the cast armor of same thickness.
At least in the US they didn't often write this down in the called for specs but I believe it was implied and would explain at times why the actual thickness of a cast part may have been thicker then what one would expect on a tank.

T1 heavy tank in 1940 for example called for:
Front vertical and near vertical surfaces and turret wall, 3" minimum.
Side and rear plates 2.5"
top and bottom 1"

The armor indicated is in terms of best grade rolled plate obtainable. Castings used will provided equivalent ballistic characteristics.
And it was well known that rolled plate was stronger at the time, so an equivalent protection would indicate they wanted the casting to be slightly thicker to equal out to called for specs under rolled.

Nick the Noodle
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#379

Post by Nick the Noodle » 30 Mar 2018, 00:09

Ulater wrote:
Consensus is not the way to go imho. Science is science, not opinion.
Good thing that this discussion is almost about pure science, except for your opinions.
There is a great deal of data on weapons, much of it apparently at odds with each other. The 40 family is no exception. Until I actually own and test fire the gun I have to rely on other peoples data. The question is, who can you trust?
Its not a matter of trust.
The M62A1 should be superior to the Pz Gr 39, all else being equal.
Why?
The US 76mm should be superior to the German 75mm equivalent.
Why?

As for 89mm/3.5" armour, I am almost certainly correct with that viewpoint. When all 3 major WW2 tank producers facing the Heer have that armour on the single most area likely to be hit, it is almost certainly effective.
Strange thing about that is that as long as it is a cast armor, it fails to meet your imagined standard of 89 mm RHA protection, RHA that was a standard medium for testing, and offers better protection than the cast armor of same thickness.

There also needs to be a very good reason why the lower energy Pz Gr 39 round, with lower momentum to boot, should be able to penetrate a greater thickness of armour.
I guess its the same good reason that bumped up the penetration of captured soviet field guns by aproximately the same percentage.
If the heavier US 76mm round has a higher muzzle velocity than that of the '40' family, it has both greater energy and momentum. Unless the specific characteristics of round Pz Gr 39 itself is superior to that of the 76mm, it will be markedly inferior, having 15% less energy and 9% less momentum.

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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#380

Post by Nick the Noodle » 30 Mar 2018, 00:24

Yoozername wrote:
Nick the Noodle wrote:
Mobius wrote:I also agree that some of the 'maths' don't get it right. That is why I collect so much data. I average them all together to find a consensus.
No knock on Bovington but they did get the MV of the 75mm/L43 wrong.
The Mark V round listed, I suspect is the Vickers HV 75mm, and an error in the original report. Just a gut feeling.
He has those 'Scientific-Gut' feelings to go along with his Advanced degrees.

{I have no idea what he is saying BTW...what 'Mark V' round????]
Not all info is on the internet. You might want to consider buying books. Less stalking and failed harassment on the internet with silly user names may also be a good choice, with time spent more productively elsewhere.

Fire and Movement by the RAC Tank Museum has data on the performance on tank rounds. Page 23 has the details on the 76mm, page 24 on the PaK 40. Given that the Museum does not have a target audience, beyond giving treadheads info, I consider the evidence they provide genuine, much like Anthony Williams work on ammunition: http://www.quarryhs.co.uk/miltech.htm. BTW, the Mk V round is listed on page 22 of the museums book.

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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#381

Post by Nick the Noodle » 30 Mar 2018, 00:37

Richard Anderson wrote:
Yoozername wrote:
This is getting odd, but in fact APG was the Ordnance Department Museum in WWII.
His 'point' was that it wasn't taken very good care of, ergo,somehow it invalidates all the testing that was done that proves him to be a numbtard.

Was it not taken care of back then? Could it possibly matter? How many rusty tanks could they have outside in the elements in 1939???
Oh, I understand, but I lost track of his "point" a while ago and was just trying to clarify that historical datum. :D
The 40 family was one of the most effective guns in anybody's arsenal. It was powerful enough to prevent a medium tank to have enough armour everywhere to counter it. This why both the Soviets and USA limited effective armour to the front, 3.5" on the gun shield, and went for bigger guns instead.

The British did the same for their Challenger A30. This tank was used to support advancing Cromwells against armour, from a hull down position. Its initial armour was less than the mediums it was intended to support, but was uparmoured to 3.5" where likely to be hit. Details in David Fletcher's Universal Tank.

When everybody is using the same thickness of armour to counter the opponents main AT weapon, it is probable it is reasonably effective.

I would go even further and state, contrary to many peoples opinions, that late in WW2 everyone was producing the right tanks they required. This means no best tank of WW2, because every country needed a different tank.

Yoozername
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#382

Post by Yoozername » 30 Mar 2018, 00:53

The 40 family was one of the most effective guns in anybody's arsenal. It was powerful enough to prevent a medium tank to have enough armour everywhere to counter it.
A Soviet 45mm M42 can be said to do the same thing. Not sure if you thought out that statement? Or are you going for the 'drift' point now? That is, you are going to somehow change your argument?
If the heavier US 76mm round has a higher muzzle velocity than that of the '40' family, it has both greater energy and momentum. Unless the specific characteristics of round Pz Gr 39 itself is superior to that of the 76mm, it will be markedly inferior, having 15% less energy and 9% less momentum.
Well, ,yes...the Pzgr 39 design was superior. And it has been discussed here also. So, maybe you need to do some searches and learn.
When everybody is using the same thickness of armour to counter the opponents main AT weapon, it is probable it is reasonably effective.
Well, no, it is on you to support your knee-jerk theory. That would be reasonable.

Yoozername
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#383

Post by Yoozername » 30 Mar 2018, 01:52

And it was well known that rolled plate was stronger at the time, so an equivalent protection would indicate they wanted the casting to be slightly thicker to equal out to called for specs under rolled.
Well, not exactly. Even RHA has a spec that calls for something like -0/+6%. Meaning that all produced plate can not be under a nominal value, and not greater than a nominal value *1.06. So, a Panther front glacis might be 80mm minimum and 84mm maximum. Of course, the plate makers do not want to have rejected lots, so they will try to be on the + side a bit. the design of manufacture must take this into account when jigging up for welding.

Castings can vary much more and control of that is not that easy. Designs have to take that into account. So calling out 'equivalent protection' or more would seem odd. The casting manufacturer would have spec. Not an equivalence.

whelm
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#384

Post by whelm » 30 Mar 2018, 02:54

Yoozername wrote:
And it was well known that rolled plate was stronger at the time, so an equivalent protection would indicate they wanted the casting to be slightly thicker to equal out to called for specs under rolled.
Well, not exactly. Even RHA has a spec that calls for something like -0/+6%. Meaning that all produced plate can not be under a nominal value, and not greater than a nominal value *1.06. So, a Panther front glacis might be 80mm minimum and 84mm maximum. Of course, the plate makers do not want to have rejected lots, so they will try to be on the + side a bit. the design of manufacture must take this into account when jigging up for welding.

Castings can vary much more and control of that is not that easy. Designs have to take that into account. So calling out 'equivalent protection' or more would seem odd. The casting manufacturer would have spec. Not an equivalence.
that was to avoid wastage during production, if the plates/castings were below spec it was rejected, if it meet spec or was above (to the limit) it would be accepted. Most, all? countries had that but some often didn't follow it or allowed things that were vastly over weight through (Germany, Panther's with crazy high lower front plates at times for example probably due to needing anything and everything pushed out to the front)

They had a +/- tolerance on dimensions on the drawn plans as well as for angle, which again varied by country and date. M6 as an example again 1941 plans call for a max +1 angle tolerance for plates and only a decimal .005 inch tolerance on dimensions.

Image

This is a useful one for US armour if your only given one number and want to find what it is in either basis or actual. Other countries again had their own versions.

Yoozername
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#385

Post by Yoozername » 30 Mar 2018, 03:56

Are you trying to say that curve was used during manufacturing? or design?

0.005"? Really?

whelm
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#386

Post by whelm » 30 Mar 2018, 05:01

Yoozername wrote:Are you trying to say that curve was used during manufacturing? or design?

0.005"? Really?
0.005" is what it lists yup, mind you it's an early draft.

design and technically it should come out to that after being built if you measured in an ideal world. The chart would change a few times from start of war, mid war and end of war. So using the M6 again as an example as it's easy, hull front called for a 5 inch basis. To reach that the non angled vertical areas would need to be 5 inches actual, but the more angled a surface was the less thick it would need to be, so the upper hull front which was about 30 deg would only be around 4 inches.

The US would apply that same chart towards enemy vehicles they examined, here's a panther for example where they take actual and find basis.

Image

Also an example of a panther with a very heavy lower plate.

Ulater
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#387

Post by Ulater » 30 Mar 2018, 06:48

Unless the specific characteristics of round Pz Gr 39 itself is superior to that of the 76mm,
Yes, it is superior.

Yoozername
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#388

Post by Yoozername » 30 Mar 2018, 15:07

It would appear that handwritten document is a British (CW?) one? They spell 'Armour' instead of Armor. It also says that the information in brackets [armor basis) has somehow been obtained from 'US Sources' originating in Russia. Very interesting. What is the last part HQ 3352...? Is there a date or where is that document from?

The 'Armor Basis Curve' is for US RHA?

Richard Anderson
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#389

Post by Richard Anderson » 30 Mar 2018, 17:11

Yoozername wrote:It would appear that handwritten document is a British (CW?) one? They spell 'Armour' instead of Armor. It also says that the information in brackets [armor basis) has somehow been obtained from 'US Sources' originating in Russia. Very interesting. What is the last part HQ 3352...? Is there a date or where is that document from?

The 'Armor Basis Curve' is for US RHA?
DSD (W) looks also to be a British office abbreviation, but not one I have run across before. It would be very interesting to see the earlier report referenced, which is the "HQ 3352-4?" That appears to be a file serial #. I have never run across any American technical intelligence on the Panther indicating American personnel measured the armor on a Panther in the Soviet Union. I would be fascinated to have more context on this snippet. What is the archival reference, what was stapled to it?
Richard C. Anderson Jr.

American Thunder: U.S. Army Tank Design, Development, and Doctrine in World War II
Cracking Hitler's Atlantic Wall
Hitler's Last Gamble
Artillery Hell

Yoozername
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Re: 7,5 cm Kwk/StuK/Pak 40 Firing Table Data

#390

Post by Yoozername » 30 Mar 2018, 18:57

Yes, it is interesting and the source would be great. But it is a design tool for armoring a tank, or guesstimating what an enemy tank might have as far as protection. Again, we need to factor in armor type/quality.

Here is a Panther armor thickness drawing. Please note these are NOMINAL dimensions. There is no tolerance or GDT like modern drawings have. In fact, there are RHA and castings in the drawing. Casting of note is the turret frontal armor of the Panther. It, and the mantlet (not shown) are castings. I would expect most manufactured Panthers to have variance ABOVE the NOMINAL armor thickness dimension called out here.

I believe this is from a thread Welm posted to, so he can add a link if he likes.

Image

This picture shows the casting along with its casting #106...the casting include both the side 50mm 'ears'...the casting part is the 'yellow' paint and does not include the white parts that are mounted into it. A bad design IMO.

Image

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