Long 88mm lacking punch?

:USERNAME: · September 4, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by cbo:

While this is from Spielberger: "Panther..."

http://www.mobilixnet.dk/~mob75281/pic/diag/75mmKwK42velocity.jpg

Claus B

I am fascinated by this graph. A rough guess would be that the average velocity of the HE shell for the panther out to 1500 meters is 800 meters a second. Thats roughly a little less than 2 seconds flight time TO 1500 meters.

If it were a stugL24 firing, I would put the flight time at 4.25 seconds.

I am guesstimating these numbers but would like to make a valid point. High velocity in direct fire makes a BIG difference. The german L24 and L48 and L70 all fired the same HE shell and when DIRECT firing HIGH VELOCITY pays off. You CAN'T adjust fire till the shell lands and as the numbers show, a low velocity weapon is waiting while a high velocity weapon could have his sights already adjusted. Throw in the fact that the high velocity weapon is more accurate also and I rest my case.

Just how important SPLIT seconds can be is demonstrated in "IN DEADLY COMBAT" by Bidermann. He describes KOing soviet tanks and inspecting one that didnt burn out. He climbs inside and looks through the russian sights and sees his own AT gun possition. There was a shell in the red gun and the PAK gun blew away the soviet gunner before he could trigger the main weapon. A fraction of a second made the difference between life and death. The author seems to be KOing heavy soviet armor with a 37mm using some kind of tungsten round BTW. He also describes beating back determined soviet infantry attacks with the pak 37mm anti-personnel (not HE but grapeshot I suppose)rounds.

Lewis

PS I love this stuff

aka_tom_w · September 4, 2000

Lewis says:

"I am guesstimating these numbers but would like to make a valid point. High velocity in direct fire makes a BIG difference. The german L24 and L48 and L70 all fired the same HE shell and when DIRECT firing HIGH VELOCITY pays off. You CAN'T adjust fire till the shell lands and as the numbers show, a low velocity weapon is waiting while a high velocity weapon could have his sights already adjusted. Throw in the fact that the high velocity weapon is more accurate also and I rest my case."

Right on Lewis!

Many of us here have been saying things like this all along.

These high velocity rounds travel along a straighter path, get there faster, penetrate deeper, and thanks to range finders on Flak 88's and Zeiss gunnery optics and mostly smokless german powder, these rounds were MUCH more deadly accurate at long range (over 2000 meters) than they modeled in CM.

The round arrived at the target sooner, the German gunners could see it better, (great optics and smokless gun powder) so the rate of fire and the accuracy should both be modeled in CM to give these german high velocity rounds a much great chance to hit and higher rate of fire and deeper penetration ability than they now enjoy.

Just my opinions, as there are plenty of others here quoting research, stats and numbers.....

-tom w

------------------

<BLOCKQUOTE>quote:<HR> "Following are opinions (very abridged because of the size of this post) of members of the 66th and 67th Armored Regiments and 2nd Armored Division:

The consensus of opinion of all personnel in the 66th Armored Regiment is that the German tank and anti-tank weapons are far superior to the American in the following categories.

Superior Flotation.

Greater mobility. This is directly contrary to the popular opinion that the heavy tank is slow and cumbersome.

The German guns have a much higher muzzle velocity and no telltale flash. The resulting flat trajectory gives great penetration and is very accurate.

The 90-mm, although an improvement, is not as good as either the 75 or 88. If HVAP ammunition becomes available, it will improve the performance of both the 76-mm and 90-mm guns.

German tank sights are definitely superior to American sights. These, combined with the flat trajectory of the guns, give great accuracy.

German tanks have better sloped armor and a better silhouette than the American tanks.

The M24 tank has not been available long, but has created a very favorable impression.

The M4 has been proven inferior to the German Mark VI in Africa before the invasion of Sicily, 10 July 1943. "

-Brigadier General J. H. Collier, Commanding Combat Command "A"

Paul Lakowski · September 4, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by Kurtz:

Could you please explain this, I don´t understand what you mean by depth in this context. Do you by any chance mean diameter? I that case it makes sense to me.

Yes the depth is meant to be diameter.

:USERNAME: · September 5, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by aka_tom_w:

The round arrived at the target sooner, the German gunners could see it better, (great optics and smokless gun powder) so the rate of fire and the accuracy should both be modeled in CM to give these german high velocity rounds a much great chance to hit and higher rate of fire and deeper penetration ability than they now enjoy.

I was quoting HE but the argument can be made for AP of course. Compare AP flight times for a panther and a shereman 75mm at 1500 meters!!

A flat trajectory is more forgiving at range and allows hits where low velocity rounds would come up short or fly long.

I believe someone posted info from a french after-war evaluation of the panther gun and claimed that HE rounds could score a hit in about 4 rounds at 2000 meters. Thats scary shooting. Bet it would take a dozed rounds from a sherman and those dozen rounds would take alot longer.

Heres a factoid. The german 75mmL24 could max out a round to 6200 meters range. It took 23.5 seconds to get there.

Lewis

Simon Fox · September 5, 2000

But tom, the greater accuracy of a high velocity gun is modelled in the game IIRC, please see page 66 of the manual. I am not sure if the relationship between ToF, RoF and accuracy is modelled but it is alluded to in a round about way so it may be.

It would be nice if we could keep discussions of gun accuracy/optics etc seperate from this discussion of armour penetration. This thread is confusing enough as it is without going off on a tangent, though thanks to John for his 'summing up' which was most appreciated. I have some comments and questions, his post is on page 8.

I think it is important to put the discussion in its context. Generally, as I see it a multitude of factors determine armour penetration. These factors have varying quantitative significance to the final outcome. On top of this is an overall statistical uncertainty. As currently implemented CM accounts for by far the most significant factors involved but not all.

How significant overall are the deviations and how significant for specific instances are the deviations?

Can the extent of the most significant deviations be accounted for by known ballistic effects?

Can these deviations be modelled readily?

<BLOCKQUOTE>quote:<HR>1). The US & Brit LF test plate was 240 - 250BHN which was the same BHN of the plate used on their tanks, which would have BOOSTED actual penetration results for all German ammunition.<HR></BLOCKQUOTE>

Doesn't it actually decline if the projectile 'overmatches' the plate?

<BLOCKQUOTE>quote:<HR>The formula can't distinguish between rounds with different nose shapes, or different hardness, and materials, nor does it predict the angle-dependant performance of armour piercing caps.<HR></BLOCKQUOTE>

You are extrapolating a little too much there. The formula may be the 'basis' for CMs calculations but at least some of the factors you cite are accounted for in some way. I may be wrong but the manual indicates so, as do previous discussions here. IIRC the differences in projectile quality are in some way incorporated.

PzKpfw 1 · September 5, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by Simon Fox:

I think it is important to put the discussion in its context. Generally, as I see it a multitude of factors determine armour penetration. These factors have varying quantitative significance to the final outcome. On top of this is an overall statistical uncertainty. As currently implemented CM accounts for by far the most significant factors involved but not all.

Agreed.

<BLOCKQUOTE>quote:<HR>

How significant overall are the deviations and how significant for specific instances are the deviations?

Good question's Tom as I realy don'y know the deviation examples that stuck out concerned guns over 75mm, Ie, KwK.43, 90mm,& 17lb which showed an inconsistancy with published performance data, you can see the ratio in Claus's post in the summery.

The 90mm APCR-T & 17lb were since adjusted closer to Hunnicuts 30^ data. The 90mm T-33 APCBC performance in CM compared to Hunnicutt's data is quite high.

<BLOCKQUOTE>quote:<HR>

Can the extent of the most significant deviations be accounted for by known ballistic effects?

I would think so but leave the answer up to Paul etc. I compile data pretty good but get lost in the math all to easy.

<BLOCKQUOTE>quote:<HR>

Doesn't it actually decline if the projectile 'overmatches' the plate?

Overmatching means the target plate is thinner than the projectile diameter. Ie, the more the round overmatches the armor, the armor offers less protection vs obliquity of impact. Which increases penetration of overmatching projectiles.

German test plate at 300 BHN was around 10% more resistant to overmatching projectiles then US, UK plate @ 240 - 250 BHN, US & UK plate used in their AFVs matched their test plate. Below is an example of the diference, British results vs 250 BHN test plate:, German results vs 300 BHN test plate: in ( )'s

7.5 cm KwK.40 fireing Pzgr.39 APCBC @ 30^

500Yrds - 106mm (92mm)

8.8 cm KwK. 36 L/56 fireing Pzgr.39 APCBC @ 30^

500yrds - 124mm (103mm)

Soviet plate at 400 - 500BHN was very brittle due to its high hardness & tended to break up when hit repeatedly by overmatching projectiles. T-34's etc were very vulnerable to the 7.5cm L/48, 7.5cm L/70 & 8.8cm L/56 guns.

This is OT but it brings up diferent armor value science used by the difering countries as well in that both the Germans & Russians used critical angle critera in developing their armor plate Ie, the obliquity angle at which the armor material will defeat a KE penetrator at a specific impact velocity.

The US & UK critera was basicly range in relation to impact, Ie, in where the armor defeats the projectile, or the projectile defeats the armor, in otherwords how close the armor could get to an enemy tank or AT gun, before being holed.

<BLOCKQUOTE>quote:<HR>

You are extrapolating a little too much there. The formula may be the 'basis' for CMs calculations but at least some of the factors you cite are accounted for in some way. I may be wrong but the manual indicates so, as do previous discussions here. IIRC the differences in projectile quality are in some way incorporated.<HR></BLOCKQUOTE>

Simon, I am not sure what effects the formula has on CMs penetration values Armor quality is covered on certian AFVs Ie, the PzKpfw IV J is rated at 95% as is the Whirblewind, the Panther Ausf G is rated at 85% the Tiger E late has no armor rateing & the Tiger II is rated at 90%.

The US M4 Sherman is rated at 85% (which is interesting in itself),while their is no rateing for the M4 76mm (w), M4 76mm Jumbo, M4 Easy 8, M24 Chafee, or M26 Pershing.

All I have been told when I questioned Charles assertion that the Wa Pruf LF data for the KwK.43 was incorrect, was to get the British 1950 report as it was the source & had the answers.

As you can see in the summery; Sopwiths formula had limitations; that effected the mathmatical formula especialy concerning obliquity of impact. & dealing with test plate results, as in the results on any steel tested above the baseline steel, produced deviations as high as 150 f/s in the results. As well as their was no provision for calulateing diferences in German face hardened armour vs AP projectiles or the AOI dependant APCBC performance, or penetrator material diferences etc. I have no idea how these areas not covered by the Report were modeled in CM.

Regards, John Waters

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"I can picture in my mind a world without war, a world without hate. And I can picture us attacking that world because they'd never expect it. " -Jack Handey

[This message has been edited by PzKpfw 1 (edited 09-05-2000).]

Simon Fox · September 5, 2000

<BLOCKQUOTE>quote:<HR>German test plate at 300 BHN was around 10% more resistant to overmatching

projectiles then US, UK plate @ 240 - 250 BHN, US & UK plate used in their AFVs matched their test plate.<HR></BLOCKQUOTE>

This is interesting John because I always understood precisely the opposite for normal impacts. BTW I am not sure that you can use different allied and german test figures to prove your point. You need to have data from the same test with the same gun against different BHN plates.

Overmatching projectiles are those for which the ratio of calibre to armour thickness is greater than one.

Accordingly I have always understood that for overmatching projectiles the resistance to normal impact decreases as the hardness of the armour increases (ie BHN increases). Furthermore this relationship is non-linear and resistance declines quite rapidly as hardness increases. Therefore German 300BHN plate should actually be less resistant to an overmatched projectile than US/UK 245BHN plate.

For example the US 57mm APC round defeats a 38mm 300BHN plate at 378m/s whereas it defeats an equivalent thickness 245BHN plate at 393m/s (overmatching ratio of about 1.5:1) (this was from a US source will have to dig it out when I can remember where from!).

Paul Lakowski · September 5, 2000

Well the deviation can be immence. According to Jonas Zukas the difference measured in terms of ballistic limit penetration , the maximum difference can be ± 200 m/s striking velocity , but this only covers a small % of hits. What are these variations, well OTOH they are ...

Actual Muzzle velocity ± 50m/s

Actual plate hardness ± 25BHN

Actaul projectile hardness ± 25BHN

Actual YAW this can be ± 5°

Actual Plate thickness ? In the german case plates were stated thickness or over by 5mm. In the case of Cast armor the variation in actual cast thickness could be as much as ± 1cm in actual thickness [Pershing tank turret]

Flaws in the projectile or plate metallurgy

Individually these don't account for much but when all the ducks are in a row 1-2% of the time the difference could be ± 20-30% penetration value around a given mean data point.

You understand this is seperate from the criteria that John refers to but since the Russian value is 75% and the American value is 50% that suggest atleast a 5% difference for the same target plate hardness . If the values are 250-275BHN difference thats about 5% difference [from memory].

PzKpfw 1 · September 5, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by Simon Fox:

This is interesting John because I always understood precisely the opposite for normal impacts. BTW I am not sure that you can use different allied and german test figures to prove your point. You need to have data from the same test with the same gun against different BHN plates.

Yes Simon, the more the round overmatches the armor, the less protection the armor gives thru obliquity. This is interesting and brings up some interesting questions Ie, why are the effects of overmatching so diferent concerning resistance in German armor @ 300BHN compared to what one would expect from the overmatch definition?.

Was it becase of their use of hardening techniques? & what effect did the German use of Case Hardening & flame hardening their armor have vs overmatching projectiles.

The British BIOS report states that the German believed Flame Hardening had superior ballistic properties to Case hardening, and FH was used on all German plate up to 80mm. did this provide more protection per mm vs Overmatching, the general consensus has been yes, it did, but how much?. German WW2 plate is generaly considered 10% more resistant per mm then US & UK plate at all hardnesses why. Simon?.

Another example to both our points on overmatch effects, is Soviet armor @ 400 - 500 BHN was designed to defeat undermatching projectiles (37 - 50mm) as was the Shermans armor which was developed as proof vs the German 37mm PAK.

But when vs the 75L48 ammunition & above Soviet armor cracked on repeated hits with whole sections being blown out it offered no protection vs repeated hits, while the Sherman armor @ 240 - 250BHN under repeated penetrations vs overmatching projectiles didn't break up, & still offered follow up protection vs repeated impacts because of the lower plate hardness.

This also brings up the question of why high hardness steel(HHS)@ 270 - 300BHN if it is so vulnerable to overmatching is still used today in some MBTs and reportedly offers more KE resistance then say 250BHN armored steel.

The British results were used as an example Simon, to show difereing results with the same guns vs both countries diferent test plate standards & the results unintentionaly highlight overmatching as well. But compare the overmatching German penetration results vs the British results.

Each Country in WW2 tested captured guns vs their own test plates standards, instead of against their enemy's test plate standards. The US & UK test plate; used to test these captured guns was of lower quality material & BHN then German test plate, as well as that the measure of sucess criteria was much more leniant then the German standards.

It is very Interesting that the 57mm test was vs '300'BHN plate Simon, was it hardened plate or standard untreated?, pls find the source & post it or email it to me as Ill want to add it to my files.

Regards, John Waters

--------------

"die verdammte Jabos".

[This message has been edited by PzKpfw 1 (edited 09-05-2000).]

PzKpfw 1 · September 5, 2000

DOH!!

[This message has been edited by PzKpfw 1 (edited 09-05-2000).]

Simon Fox · September 6, 2000

Before I go on too much I need some clarifications.

By flame hardened do you mean face hardened (FH) which I beleive was flame and or later induction hardened?

I am pretty sure the results were for standard 300BHN RHA plate (ie not face hardened), I only wrote down the stuff for 245 and 300 BHN but IIRC a range of BHN values were tested.

Are all german test data for 300BHN FH plate? If so you are comparing apples and oranges. If you want to examine the effect of hardness on resistance to penetration for a variety of projectile calibres then you must reduce the variables to one. Therefore you must use either FH or RHA armour at all BHN not a mixture. Otherwise you are introducing the effects of the face hardening process.

Isn't it the case that FH armour is less resistant to penetration than RHA against capped projectiles? And that the converse is true for uncapped projectiles?

Paul Lakowski · September 6, 2000

Face hardened plate is not the same as hardened plate , all sides used RHA with ranges from 240 - 380 BHN these all resisted well with the increasing plate hardness blunting the projectile tip hardness unless that was more than 1.5 times the target hardness.

Semi hardened plate is 400-480 BHN while hard steel is usually ~500-600 BHN.

Face hardened plate was 'hard steel' on the front face and RHA on the rear, which was achieved by heat treating the one side.

German test plate was , to my knowledge, 275 BHN plate but the tolerance on plate manufacture was ± 25 BHN so the plate is some times refered to as 250-300 BHN.

PzKpfw 1 · September 6, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by Simon Fox:

Before I go on too much I need some clarifications.

By flame hardened do you mean face hardened (FH) which I beleive was flame and or later induction hardened?

The BIOS report states that Flame Hardening was used on all plates 30 - 50mm thickness & on 60 & 80mm plates Ie, the Panthers nose was FH, as were all all machine gun mantlets, & ball mounts. Plates under 30mm were incapable of being Flame Hardened as distortions occured in all attempts on Flame Hardening with less then 30mm thickness as the thickness declined below 30mm the distortions became greater.

Flame hardening was chosen to replace Case Hardening, because it was cheaper, & more eficent for mass production,& had better 'ballistic qualities' then Case Hardening.

The only areas not FH on the plate was the plate edges where welding had to be done, it was found that welding attempts on FH plate tended to crack the plate. Not all plants could FH plates above 50mm Ie, Krupp had no facilities for Hardening plates above 50mm thickness.

Electrical Induction Hardening (IEH) was initialy an Kriegsmarine Project set up in 1937 in secret, Krupp never knew of the project or plants purpose nor knew of the LF tests. A plant was set up at Dortmund Hoerde, in 1937 & operational in 1938. A second IE hardening plant was set up by Deutsche Edelstahlwerke in Hanover.

The Dortmund Hoerde plant's purpose was to provide the Kriegsmarine with an alternative source of hard faced plates, to replace the carburised plates from Krupp only plates of 100 - 150mm thickness were EI hardened.

The Kriegsmarine shut down the Dortmund plant in 1942 - 1943. The Dortmund plant produced over 1000 tons of EIH plate, that was stated to be of comparible quality to Krupp plate of the same thickness. The interesting part is that none of the plate was ever used by the Kriegsmarine, as they had no need for it, & it all was used for live fire tests.

The Hanover plant produced IEH 30 - 50mm thickness plates for the PzKpfw. III & IV tanks, from 1942 on. with 100 hulls produced a week & 1000 tons of armor plate per week. For this 2000 tons of steel were used , with 1500 tons produced at the plant & 500 tons suplied from the Krefeld Works, till the factory was destroyed in a March 1945 bombing raid.

The plate harness depth was 10% of the thickness of the plate. An IE Hardened plate of 23mm was the equivelnt of 40mm RHA & IEH plates were considered superior in resistance to untreated RHA plates. As with FH the edges were left untreated for welding. The Hanover plant could not IEH plates above 50mm thickness due to lacking the equiptment needed.

<BLOCKQUOTE>quote:<HR>

I am pretty sure the results were for standard 300BHN RHA plate (ie not face hardened), I only wrote down the stuff for 245 and 300 BHN but IIRC a range of BHN values were tested.

<HR></BLOCKQUOTE>

That would effect the results. All of the US live fire tests I have seen for WW2 used 240 - 250 BHN plate, vs their own ammunition (75 - 90mm) & vs German ammunition & as low as 220 BHN for small calibre (37mm) tests. Was this an wartime test or after war? if it was during the war it was an rare event.

<BLOCKQUOTE>quote:<HR>

Are all german test data for 300BHN FH plate? If so you are comparing apples and oranges. If you want to examine the effect of hardness on resistance to penetration for a variety of projectile calibres then you must reduce the variables to one. Therefore you must use either FH or RHA armour at all BHN not a mixture. Otherwise you are introducing the effects of the face hardening process.

Most likely yes, Simon all the plate production plants LF tested vs FH plate, they had to to pass inspection so it stands to reason that the LF plate used by Wapruf was FH treated.

Heres the fun part Simon, German test plate was of a higher standard then their production plate, hardness was generaly 250 - 300 BHN with the norm I have seen quoted 300BHN, can I say catagoricly that all the test plate was 300BHN no.

I know this Simon & thats the biggest problems in these discussions as I said earlier captured guns & ammunition were tested useing whatever country captured them's standard test plate.

<BLOCKQUOTE>quote:<HR>

Isn't it the case that FH armour is less resistant to penetration than RHA against capped projectiles? And that the converse is true for uncapped projectiles?<HR></BLOCKQUOTE>

No its the oposite as I understand it, the face was hardened steel to an certian depth, which was backed up by the underlayer of RHA which increased resistance. Ie, 50mm plates were Flame Hardened to a depth of 3 - 5mms and It was also possible to increase the depth by pre heating the plate before the FH process.

The face hardness requirement which varied on the composition of the steel was 200 kilo (127 tons). per square mm(around 555BHN). This requirement could not be attained if the carbon content was below 40%.

Regards, John Waters

----------

"I can picture in my mind a world without war, a world without hate. And I can picture us attacking that world because they'd never expect it. " -Jack Handey.

[This message has been edited by PzKpfw 1 (edited 09-07-2000).]

Dittohead · September 7, 2000

Although not specifically related to the 88mm, I have a question concerning the US Tunsten round.

From the charts 88mm Pzgr 40 HVAP increases penetration say 25%. But US HVAP increases penetration almost 100%. Is this right and why such a big jump in US rounds?

Tony

Paul Lakowski · September 7, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by Dittohead:

Although not specifically related to the 88mm, I have a question concerning the US Tunsten round.

From the charts 88mm Pzgr 40 HVAP increases penetration say 25%. But US HVAP increases penetration almost 100%. Is this right and why such a big jump in US rounds?

Tony<HR></BLOCKQUOTE>

Cause the tip to body diameter of the German AP 40 shot [except the 50mm ] are around 9:1 while the US rounds for the 90mm gun and others are 14:1 or more. This produces a greater penetration for the same mass Velocity and projectile length.This is also why they have worse slanted penetration.

aka_tom_w · September 7, 2000

<BLOCKQUOTE>quote:<HR>Originally posted by Dittohead:

Although not specifically related to the 88mm, I have a question concerning the US Tunsten round.

From the charts 88mm Pzgr 40 HVAP increases penetration say 25%. But US HVAP increases penetration almost 100%. Is this right and why such a big jump in US rounds?

Tony<HR></BLOCKQUOTE>

Good question

also is the HVAP round the same a the tungsten round? is that the same round with different names?

anyone?