Long 88mm lacking punch?

[cbo]

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1:

17Pdr APDS @ 30^ Source: Hunnicutt's Sherman.

500yrds - 192mm

1000yrds 176mm

17Pdr APDS @ 30^ Source: CM Data

500ms - 190mm

1000ms - 190mm<HR></BLOCKQUOTE>

You must have blinked, John - it is even worse :

500yds - 208mm

1000yds - 192mm

1500yds - 176mm

Hunnicutt p. 565.

Claus B

[This message has been edited by cbo (edited 08-26-2000).]

[Paul Lakowski]

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

You must have blinked, John - it is even worse :

500yds - 208mm

1000yds - 192mm

1500yds - 176mm

Hunnicutt p. 565.

<HR></BLOCKQUOTE>

In the Ordnance board report the values for 17Lb APDS into 'homo plate' are reported to be

<PRE>

0° 30°

500 yrds 250mm 208mm

1000 yrds 232mm 191mm

2000 yrds 192mm 161mm

</PRE>

I was looking at Hunnicutts Pershing book and the 90mm ammo diagrams that Claus posted to the TANK NET. Claus could you post the link here?

The US projectile tips look different than the German, the 90mm APCBC has a tip to rod diameter ratio of 9:1 compared to ~ 4:1 for german APCBC rounds while the HVAP shot is 14:1 like the british APDS and different from the german AP 40 type shots which are ~ 9:1 for the 75 and 88mm guns.

May be this has an impact in sloped penetration , in the diagrams the difference between 30° and 0°at 1000 yards seems like 1.25 for this APCBC round. We know from APFSDS work that theres a hugh difference in penetration route of a pointed rod compared to a flat tipped rod - flat tipped rods take a shorter route through the armor while sharp tipped rods take a longer [ Vs thin plates at sharp angle IE 70°]. This is similar to what happens with ricochet- sharp tipped rods ricochet at lower velocities than flat tip rods.

So in short the sharper tipped projectiles get better penetration Vs vertical plate but suffer more Vs slanted armor.

[This message has been edited by Paul Lakowski (edited 08-26-2000).]

[cbo]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski:

I was looking at Hunnicutts Pershing book and the 90mm ammo diagrams that Claus posted to the TANK NET. Claus could you post the link here?<HR></BLOCKQUOTE>

Certainly.

These are from papers provided by Robert Livingston:

http://www.mobilixnet.dk/~mob75281/pic/diag/17pdrAPBCvelocity.jpg http://www.mobilixnet.dk/~mob75281/pic/diag/90mmHVAPvelocity.jpg http://www.mobilixnet.dk/~mob75281/pic/diag/90mmAPCvelocity.jpg

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

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

Claus B

[cbo]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski:

The US projectile tips look different than the German, the 90mm APCBC has a tip to rod diameter ratio of 9:1 compared to ~ 4:1 for german APCBC rounds while the HVAP shot is 14:1 like the british APDS and different from the german AP 40 type shots which are ~ 9:1 for the 75 and 88mm guns.

<HR></BLOCKQUOTE>

I am not shure how you calculate the tip to rod diameter or ogive radius but cross-sections of US 76mm and 90mm projectiles compared with the 7,5cm PzGr 39 shows that the penetrating cap of the German projectile is nearly flat while the actual projectile have a fairly shot but pointed nose.

The cap of the US projectiles follow the nose of the projectile which is slightly longer than the German projectile. Unfortunately, I do not have a cross-section of the 8,8cm PzGr 39-1, but I would be surprised if it did not look like the other rounds with the blunt penetration cap.

Claus B

[PzKpfw 1]

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

You must have blinked, John - it is even worse :

500yds - 208mm

1000yds - 192mm

1500yds - 176mm

Hunnicutt p. 565.

Claus B

<HR></BLOCKQUOTE>

LOL no my power blinked out, while I was trying to correct it we just got it back on, I just edited it then saw this...

Regards, John Waters

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

People who can smile when things go wrong

have found someone else to blame.

[Dittohead]

Bumping this excellent thread.

[:USERNAME:]

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

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

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

Claus B

<HR></BLOCKQUOTE>

At 2000 meters the panther HE is traveling at 650 meters a second? It had to be deadly accurate. I bet you could walk some into a window of a building at that range. Very scary.

If I wasnt so tired I would use this data to find time of flights. A 75mmL48 AP takes 1.44 seconds to go 1000 meters and reaches a height about 2.5 meters max. Its INITIAL velocity is 750 meters a second. So a panther 75mm HE would take less yet its the same shell really.

I find this crap too fascinating. I should have my head examined.

Lewis

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

At 2000 meters the panther HE is traveling at 650 meters a second? It had to be deadly accurate. I bet you could walk some into a window of a building at that range. Very scary.

If I wasnt so tired I would use this data to find time of flights. A 75mmL48 AP takes 1.44 seconds to go 1000 meters and reaches a height about 2.5 meters max. Its INITIAL velocity is 750 meters a second. So a panther 75mm HE would take less yet its the same shell really.

I find this crap too fascinating. I should have my head examined.

Lewis<HR></BLOCKQUOTE>

No Lewis, when you start dreaming up formulas to solve the intractable problems of terminal ballistics [ like I did last nite] then you need your head examined

[PzKpfw 1]

Rick pointed out to me tonight after reading this topic some, that if you look at the US 90mm chart Claus posted the URL to and carefuly examine the curve, you'll see that it could penetrate 190mm @ 30^ at roughly 1000ms and 244mm @ 0^. And added that the chart also indicates that the 90mm ammunition couldn't defeat the Panther frontaly above 400ms.

This pretty much meshed with Jim Warfords (anyone who reads Armor magazine has seen Jim's Soviet/Russian work) posting on Tankers; a year or more ago relating that he had watched the actual US Army Ordinace Dept live fire tests, films of the 90mm vs the Panther, and the 90mm ammunitions inability to defeat the Panther's glacis even at close range.

Anyway thought this was all interesting as its a pretty much given in looking at various games penetration data that the 90mm can be kill the Panther at longer ranges and I also recently read somehere as well, that that British 17lb APDS could not defeat the Panthers glacis either; due to the 55^ slope.

Paul sending you snippets of Ricks E-mail as he has some questions for you; on W-C and 60mm @ 2000ms @ 60^ etc.

Regards, John Waters

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

People who can smile when things go wrong

have found someone else to blame.

[This message has been edited by PzKpfw 1 (edited 08-28-2000).]

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski:

This is from Karl Brandel.

"you find the test of the KWK43 against the Tiger II frontal turret armour which it perforated completely (185mm). It exited

the tank through the rear turret armour (80mm IIRC = > 265mm at nearly the vertical) (8^)."

Now this could be within 20% of 230mm vertical penetration value @ 100m but how would you stretch this to 170mm?<HR></BLOCKQUOTE>

Paul this got me thinking, I read an account from an Waffen SS Panther crew with 6th SS Pz Army in Hungary during the retreat, they had to destroy Tanks they had no fuel for and only had enough explosives to detroy 1 tank, so they decided to use the explosives on their Panther and use the Panther to destroy the other AFVs to deny them to the Soviets.

So they destroyed all the vehichles except 1 with the Panther, the last AFV besides their own was a Tiger II, so they shot it at PB range frontaly like 5 times and all rounds failed. They finaly gave up on a frontal KO and destroyed it with a rear hull hit after several shots, then destroyed their Panther and began a walking retreat.

Regards, John Waters

------

"Go for the eyes Boo, go for the eyes!!".

[Simon Fox]

Some great posts from Claus (cbo) there. Good to see some lucid and logical examination on both the sources of various published data (ie empirical or calculated) and also some narrowing down of where exactly various groups of data deviate and some rationale for this deviation.

[PzKpfw 1]

A lot of this research probably would have been easier especialy the access to the actual live fire test data reports and ammunition specs had the main German Artillery & Anti tank proveing grounds not been in the Soviet sector when the war ended.

Williams & Backofen's Soviet Kinetic Energy Penetrators Armor Magazine article details that the Polte firm in Magdeburg was the primary developer of all German AP ammunition, as well as the leader in the German ballistic research feild. Polte was working on shell carrier crush up & the incendiary effectiveness, but when the war ended all the data ended up in Soviet hands.

The article also goes into German use of solid aluminum & or magnesium windscreens on arrowhead ammunition (later plastic and steel) to attain an behind armor incendiary effect and the Soviet use of solid aluminum windscreen on Soviet KE penetrators.

Regards, John Waters

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

People who can smile when things go wrong

have found someone else to blame.

[This message has been edited by PzKpfw 1 (edited 08-28-2000).]

[Rattus]

"you find the test of the KWK43 against the Tiger II frontal turret armour which it perforated completely (185mm). It exited the tank through the rear turret armour (80mm IIRC = > 265mm at nearly the vertical) (8^).

Now this could be within 20% of 230mm vertical penetration value @ 100m but how would you stretch this to 170mm?"

The thickness of multiple armour plates are not straightforwardly additive. I think a good rule of thumb works out to be 1/2 the thickness of additional plates - so in this example it would only be effectively 225mm - which is very close to 20% of 170mm. Furthermore, the inside of the rear armour plate wuld not be face hardened.

Note the above rule of thumb dooes not work for laminated plates.

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Rattus:

"you find the test of the KWK43 against the Tiger II frontal turret armour which it perforated completely (185mm). It exited the tank through the rear turret armour (80mm IIRC = > 265mm at nearly the vertical) (8^).

Now this could be within 20% of 230mm vertical penetration value @ 100m but how would you stretch this to 170mm?"

The thickness of multiple armour plates are not straightforwardly additive. I think a good rule of thumb works out to be 1/2 the thickness of additional plates - so in this example it would only be effectively 225mm - which is very close to 20% of 170mm. Furthermore, the inside of the rear armour plate wuld not be face hardened.

Note the above rule of thumb dooes not work for laminated plates.

<HR></BLOCKQUOTE>

This is true when the airgap between the plates is quite small say 1-8 projectile diameters , but when this distance reaches 20:1 or more and the striking velocity exceeds 800m/s the overall resistance goes up so by 900-1000m/s its 10 % , thats from actual test.

[Rattus]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski:

This is true when the airgap between the plates is quite small say 1-8 projectile diameters , but when this distance reaches 20:1 or more and the striking velocity exceeds 800m/s the overall resistance goes up so by 900-1000m/s its 10 % , thats from actual test.<HR></BLOCKQUOTE>

Thanks Paul, can you clarify your post a little for me please, you are referring to the striking velocity against the first plate(?) and saying that at the mv of 800+ m/s with the plates space 20+ calibres apart the resistance of the second plate iceases with initial striking velocity until at c1000/ms the resistance is effectively 10(100?)%?

[Ben Galanti]

Just a quick correction on the CM data for the 17 pdr at 30 degrees.

500m -- 201mm

1000m - 190mm

It had be listed as 190mm for both in a couple of posts. They're pretty close to the hunnicut values, but the yards to meters thing also needs to be adjusted for.

Ben

[jpinard]

I think everything in CM is perfect, and wish you all would stop wasting BTS's time.

For those of you complaining about the smallest thing like this... Do you have no life???

Steve & Charles, pleas start working on CM2. I'm really looking forward to the Russian Front! I'm hoping I can take the Germans and conquer both Stalingrad and Moscow!

[Paul Lakowski]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Rattus:

Thanks Paul, can you clarify your post a little for me please, you are referring to the striking velocity against the first plate(?) and saying that at the mv of 800+ m/s with the plates space 20+ calibres apart the resistance of the second plate iceases with initial striking velocity until at c1000/ms the resistance is effectively 10(100?)%?<HR></BLOCKQUOTE>

No thats the target as a whole, buy 1100 m/s its 20% for AP type warheads , while APFSDS is ~ 10% loss over 1.2 to > 2.0 KM/s.

It makes a big difference , Ogorkeiwcz reports that spaced plates reach about 1.2 Em compared to solid RHA of the same mass.

<BLOCKQUOTE>quote:</font><HR>

Just to expand here it should look roughly like this .

<PRE>

standoff 1-3 4-5 6-7 8-10 15-20 [in projectile diameters]

Relative change -10% -20% -10% 0% + 10%

</PRE>

Its been noted that slanted spaced impact is more severe than normal impact as YAW plays a role.In the case of Ogorkiewcz's 1.2 , he's probably refering to LEO-1A3 which features about 20-30cm air gap beteen the first and second plates. This amount of space Vs APFSDS is only going to offer 8-10:1 projectile diameters, which should offer no change in resistance. So clearly the rate of 'tumble' in the rod is significant.

<HR></BLOCKQUOTE>

John got RIcks Email , not sure about 241mm @ 30o must have been against substandard American 240 BHN target plate.

If we can get Jim & Rick [ & Steve Zaloga]here, maybe we can re invent the 'Tankers Net' He He He

[This message has been edited by Paul Lakowski (edited 08-28-2000).]

Second edit at coffee time ]

[This message has been edited by Paul Lakowski (edited 08-28-2000).]

[RMC]

Just chiming in to support this great thread.

JPinard,

CM is not perfect, not will it ever be. BUt it's damn good. Like CC before it, claims of realism will be tested. There are many people on this board. Some of them know things that Charles and Steve don't. Their participation can only help make the game better. If everyone subscribed to your way of thinking, CM would be lacking in many details that went in or were changed from user/fan input.

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by jpinard:

I think everything in CM is perfect, and wish you all would stop wasting BTS's time.

<HR></BLOCKQUOTE>

Thats fine JP your entiteled to your opinion. & I dont think anyone here whom posted believes bringing up a relevant issue Ie, turret traverse speeds, Tiger E TF armor ,German optics etc, etc, is wasteing BTS's time.

To adress both your posts:

Do you think that the Panther should be given an ahistorical traverse speed? its currently 46secs when in reality it could traverse 360^ in 18 secs @ 2500rpm this gives Shermans etc an very signifigent advantage, add that to the Panthers cost in CM, and this is not a relevant issue even though it negatively effects players use of these tanks?. If the time was taken to program these 'realism' factors into CM originaly should it not stand to reason they should be correct? or attempted to be made as correct as possible.

Did you read this thread? as it concerns historical aspects as well as an implied game aspect, thats another thing wargames especialy concerning WW2; they attract an historian crowd as well, so game boards can also reflect strong historical debates etc.

Or the trivial in your opinion, incorrect data used in the Tiger E mantlet which to you may be seen as a waste of time; while Tiger E's TF armor in CM is being penetrated @ 500ms by 75mm M61 APCBC something that did not happen in actual British wartime LF tests if it had their would never have been a need for upgunning tanks & TD's to 76mm, 17lb or 90mm guns etc.

So in your opinion were not even suposed to qustion this?. Again look at the Tiger cost in CM, justify spending the points vs their survivability w/o ppls questioning certian areas, & the fact the Tiger E mantlet was upgraded in 1.04 or any other change tells you that obviously Charles & Steve saw merit eneough in these trivial discussions to fix the topics problems. Whether you like it or not ppl are going to question what they percieve as incorrect especialy if it's a game as touted for realism as CM is. as well as that if these were such trivial matters as you imply BTS would have locked these threads by now.

<BLOCKQUOTE>quote:</font><HR>

For those of you complaining about the smallest thing like this... Do you have no life??? <HR></BLOCKQUOTE>

Why does our bringing up realism questions imply we have no life etc? because we spend our free moments playing CM & posting here.

I'd also sugest if these issues are trivial to you then don't read them, the subjects title should generaly give you enough info for you to determine if the threads trivial or not, and remember this as well; we all have diferent opinions of whats 'perfect' etc, as the old adage goes; opinions are like a##%oles everyone has one.

Basicly if ppl did not love CM so much you wouldn't have to post any of this as no one would care.

Regards, John Waters

---------

"Go for the eyes Boo, go for the eyes!!".

[This message has been edited by PzKpfw 1 (edited 08-28-2000).]

[Måkjager]

Well said John , well said

[Ari Maenpaa]

jpinard,

I really can't answer you any better than John Waters did. But couple of words anyway:

My motivation to "complain about the smallest things" is to help to get them as real as possible. To know that little details in a game (CM in this case) are "real", boosts enormously my enjoyment when playing.

After all most wargames are supposed to represent history as accurately as possible. And that is why many of us play them.

On the other hand I find it somewhat disturbing when I know for sure that something in the game is in clear conflict with reality AND that it could be fixed pretty easily.

Also I can learn much when making questions on this kind of forum because there are some very good experts contributing. This very thread, for example, has taught me many new facts about armour perforation.

I can only imagine that there are many people who think like me.

Of course perfection will never be achieved. Many factors in CM will require compromises. And this is BTS's game. They decide what to do with our suggestions.

For wasting of time: many of the questioned aspects in CMBO will be there in CM2 also. So I don't think it's counterproductive to get them fixed already in CMBO. At the same time we get even better CM1

Anyway I never meant to sound unthankful. CM is the BEST computer game I have ever played. That is why I like to contribute on this forum.

Thank You Charles and Steve.

Ari

[Bastables]

User input has had a great deal to do with why CM is so realistic. I can remember several aspect that were improved thru what some would call wasteful pedantic; The panzershreck team given the ability to run, the 2 inch mortars new ability to run, Rifle grenades for US troops, improved handling of artillery including but not limited to more realistic handling of shell dispersion and spotting round. Those are the ones that I can remember offhand, dozens more have found their way into the game due to user pedantism, the game is built from the ground up from a manic attention to detail by Charles and Steve. For instance the change in German Fieldgreay uniform to better reflect the lower quality textiles in use near the end of the war, just a waste of time eh?

John,Paul and Claus input is appreciated, there is no whining for a pet feature in this ie HMG team should be able to run as fast as Sections, this input is a part of what makes CM so dam good.

[This message has been edited by Bastables (edited 08-29-2000).]

[Simon Fox]

Here's some user whining for you Bas

SEND ME THE BLOODY MOVIE!

As for the rest of the thread there is nothing like a good argument/discussion as long as the quality is of a reasonable standard.

[Bastables]

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

Here's some user whining for you Bas

SEND ME THE BLOODY MOVIE!

As for the rest of the thread there is nothing like a good argument/discussion as long as the quality is of a reasonable standard.<HR></BLOCKQUOTE>

Ah you're one of the many who did not see the thread detaling the IP hell which has made my Email accounts unusable until the buggers get their act together and sort out my new ISDN connection

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I cannot eat these eggs, they are of completely different sizes.