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Tapered Thickness of Panther Mantlet


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OrRiginally posted by Mr. Tittles:

" http://www.geocities.com/mycenius/

http://www.100thww2.org/support/77657mm.html

If the Panther mantlet was so vulnerable to 57mm fire, why would these reports not note it?"

Why don't you try to answer your question this time? U.S. 57mm APCBC vs British 6 pdr APCBC against Panther mantlet.

I gave you a hint. What do we know about U.S. APCBC-HE?

;o)

Lorrin

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Originally posted by Mr. Tittles:

Curved surfaces distribute stress better than sharp-cornered welded

boxes, so curved mantlets acted a bit thicker than their weak granular

structure would lead us to expect. That is, they were kinda the same as

if they were RHA.

http://www.yarchive.net/mil/ww2_tank_armor.html

The old egg-shell theory of curved mantlet protection which has been discussed before. Or the Roman arch theory of curved mantlet resistance, where an arch is stronger than a plate.

Could be.

But what about the British firing tests with 6 pdr APCBC where the Panther mantlet was penetrated at a wide variety of angles. That information, which I posted some time ago, seems to have been forgotten. Those tests do not support a "curved is better" theory.

On the other hand, if one compares a curved mantlet to a flat but sloped piece of armor plate, there is more material to resist the hit and encourage a ricochet if one looks at the armor strike pictures in the Panther Fibel and thinks about it a little.

The British firing tests would be my best bet for what is really going on. I have requested additional info on the tests and am trying to obtain the precise impact angles, I currently have drawings that show the approximate location of the various hits.

Lorrin

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I think the ability of the 76mm M62 to penetrate and the inability of the 76mm M79 NOT to penetrate is more pertinent than your approximate locations of 6 pdr hits. It certainly seems that the mantlet was not RHA-like but rather face-hardened -like.

You have a very strong propensity to throw this shatter-gap into any situation where you can. In this case, its inmaterial. Whether the US 76mm had shatter gap does not address the fact that the US 76mm M86 COULD penetrate the Panther mantlet at 200 yards or so AND the 76mm M79 could not.

Do you think any of the Mycenius data supports any shatter-gap theory?

[ September 17, 2004, 04:51 PM: Message edited by: Mr. Tittles ]

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20 deg

M70 57mm AP

HOMO

500 3.9in

1000 2.9in

Face Hardened

500 3.2in

1000 2.4in

57mm M86 APCBC

HOMO

500 3.3 ins.

1000 2.9 ins.

FH

500 3.4 ins.

1000 3.1 ins.

This is penetration data for US 57mm ATG using US ammo. It, like the US 76mm ammo, shows the same properties as far as the solid shot doing better against homog armor, but not as well against face hardened armor.

If you read through..

http://www.thetroubleshooters.com/history358.html

The US unit trades AP rounds (I would guess APCBC) for british HE. The British had a AP ammo shortage and the US unit no HE. The US unit goes on to use its HE to good effect, but I wonder about the brits (maybe they only had APDS and it was innacurate?).

In any case..there is evidence that US units also had APDS..

http://www.bluespader.com/Pg13.html

[ September 17, 2004, 05:30 PM: Message edited by: Mr. Tittles ]

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If 76mm APCBC hit the Tiger driver plate at 12° side angle, the resultant resistance would equal 109mm at 0°. With shatter gap, rounds fail when they have 1.05 to 1.25 times the armor resistance, which would result in M10 failures from point blank to 550 meters range, and then penetrate from 550m to 750m.

On M10 hits against the Tiger side armor at 30° side angle, the resistance would equal 103mm at 0°, and M10 hits would be expected to fail from point blank to 800m, and then penetrate from 800m to 1000m.

http://spwaw.com/lholttg/penetration.htm

?

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Rexford,

I have a question about your latest table converting the Panther mantlet to a vertical equivalent thickness of armor. You've include a column labelled "cast deficiency" which has values ranging from .94 to .81. What does that model?

Is it a specific conversion from any cast armor to a RHA equivalency? Is it some sort of "fudge" factor applied only to the Panther? (Reminding me of the "Armor Quality" rankings in CM:BB.) Why do the values change so dramatically?

Thank you,

KEn

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Originally posted by Mr. Tittles:

I think the ability of the 76mm M62 to penetrate and the inability of the 76mm M79 NOT to penetrate is more pertinent than your approximate locations of 6 pdr hits. It certainly seems that the mantlet was not RHA-like but rather face-hardened -like.

You have a very strong propensity to throw this shatter-gap into any situation where you can. In this case, its inmaterial. Whether the US 76mm had shatter gap does not address the fact that the US 76mm M86 COULD penetrate the Panther mantlet at 200 yards or so AND the 76mm M79 could not.

Do you think any of the Mycenius data supports any shatter-gap theory?

I disagree with you on all points and have provided what I believe are reasonable explanations. You seem to disregard or downplay my explanations.

Shatter gap appears to explain many cases where 76mm M62 APCBC (not M86, as you incorrectly stated in the above quotation) fails against armor that it should defeat. So it seems natural to see if shatter gap might explain test failures or odd behavior.

Our studies of capped and uncapped rounds shows that they can have different failure regimes (penetration/effective resistance ratio's), which could account for the different effective ranges between 76mm M62 and M79.

Your observation that 76mm M79 did not penetrate the Panther mantlet at close range is not news to us, we had the Mycenius firing test report more than 10 years ago and Jim O'Neil, who provided the report to the Mycenius site, got it from me. The other firing test reports on the Mycenius site originated from our group, as did several of the other articles that are posted (a few have my hand writing on them).

We've examined the 76mm M79 AP failure issue for many years (over ten) and the data we've looked at throws out any possibility of face-hardened armor.

If the Panther mantlet was face-hardened, and you compared the face-hardened penetration of the 76mm APCBC and AP rounds at 200 yards to the 100mm mantlet center thickness, you would come to the conclusion that face-hardening alone does not explain the hit failures. Something else is occurring.

Shatter gap is one possibility. There are others.

6 pdr APCBC firing tests are more pertinent than the 76mm trials because they will show if the Panther mantlet slope effects for rounded armor hits are below, equal or greater than the slope multipliers for a flat plate at the same impact angle. That is one of the key issues that we are discussing on this thread, and addresses some of your past questions.

The 76mm M62 and M79 tests show very little regarding the ballistic resistance of the Panther rounded mantlet areas because of potential interference from other issues.

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Shatter gap theory as we've been able to detail it results in a penetration failure potential for U.S. 76mm APCBC if the "penetration/effective armor" resistance ratio is between 1.05 and 1.25, more or less.

Let's apply that to the firing test results on the Mycenius site.

Penetrates 100mm/30 degrees at 500 yards.

Well, penetration at 0 degrees is 117mm, resistance of plate is about 125mm at 0 degrees. Suggests above average penetration or below average resistance of armor, with penetration close to effective resistance. So no shatter gap.

Penetrates Panther mantlet at 200 yards. Penetration equals 123mm, a hit on the mantlet center is resisted by about 95mm, so the penetration/resistance ratio is above 1.25 at 200 yards but may fall into the shatter gap ratio beyond that range.

Just to clarify a point in my previous post, the 250m face-hardened penetration of the U.S. 76mm M79 and M62 rounds is 124mm and 123mm, respectively, which blows apart the theory that the firing trial failures against the Panther mantlet were due to face-hardened armor. Compare the data, throw out the theory.

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Originally posted by Mr. Tittles:

The US Army standard catalog of Ordnance lists the 76mm M79 against FH armor as 3.2in (81mm) at 500 yds and 2.8in (71mm) at 1000yds. This is 20 degree FH armor. I doubt that it would penetrate 124mm at 250m. You are probably looking at Homog penetration values.

76mm M79 Homog armor 20 deg

116mm at 500yds

101mm at 1000yds.

Those figures you posted are questionable and we looked at them in the past and disregarded them. We made it a point to analyze published figures before using them, since many "official" numbers are questionable.

75mm M72 AP penetrates about 95mm of vertical face-hardened armor at 0 degrees and 0 yards.

76mm M79 AP was fired at 2600 fps, versus 2030 fps for 75mm M72 AP, and based on velocity differences alone the M79 should penetrate about 95mm x (2600/2030)raised to 1.25 power, or 129mm at point blank. Throw in a larger diameter round and the 0 yard/0 degree penetration figure we just estimates increases some more.

1. Looks like the catalog contains some bad data.

2. There is nothing, anywhere, which suggests that the Panther mantlet was face-hardened.

==========================================

Now, would you please explain why a "100mm thick at its center" face-hardened Panther mantlet would defeat the 76mm M62 APCBC round beyond 200 yards? Please show the penetration and armor thickness figures to support your contention?

It would be good to see your theory backed by numbers and analysis.

My copy of TM9-1907 shows the 76mm M62 round penetrating the following thicknesses of face-hardened armor at 500 yards (the 250 yard penetration would be higher):

500 Yard Penetration of 76mm M62 APCBC

Face-Hardened Armor

======================================

4.76 inches at 0 degrees (121mm, armor is 100mm)

4.15 inches at 20 degrees (105mm, armor is 91mm)

3.65 inches at 30 degrees (93mm, armor is 84mm)

[ September 19, 2004, 08:12 AM: Message edited by: lorrin ]

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The M62 76mm round penetrates 100mm of RHA in U.S. Army Test No.1

Report on Comparative Firing Program Witnessed at Shoeburyness, Essex, 23 May 1944 by U.S. Army Headquarters ETO representatives.

at 500m. It does this twice actually with rounds 10 and 11. It does not exhibit BDF going off either. One could logically surmise that at 500 yds range, it had the potential to penetrate the panther mantlet. But in actual test against panther front, it can only penetrate mantlet at 200 yds. The panther mantlet is behaving 'tougher' than its actual thickness. If the M62 could hole 100mm of RHA/30deg at 500m (without any shattter), then why would it not have better performance against a panther mantlet?

At 100 yds and 400 yds, it fails to penetrate 120mm RHA at 30 degrees. It again shows that the BDF is not going off. It leaves gouges in the armor as a result of the hits. No where in these tests is there any mention of shattering or hits not leaving gouges. Since it CAN penetarte a panther mantlet at 200 yds, it can be logically stated that the panther mantlet is NOT equal to 120mm RHA/30 deg. In certain spots it may be equal to 120mm+ but not very many.

The complete inability of the M72 solid shot to achieve a penetration against the mantlet is very odd. Since the panther mantlet is more than likely just a cast piece of metal, it is should achieve penetration.

Its my contention that the mantlet does not behave like sub-RHA and the very agressive curvature does play into the penetration equation. It can not be equated to equations like other armor is. The 90mm solid shot M77 round does penetrate the panther mantlet, bow and turret. Interestingly, the 90mm has a harder time against the mantlet than the vertical turret front!

I suspect that the typical T/D rules are being altered by the curvature of the armor. The mantlet is acting like a tough nut to crack. The penetrating round is experiencing an increase in armor resistance as it moves through the armor. It must push material out of its way and is also experiencing side forces as it moves through. Its being squeezed and opposed. Its acting like its 'depth-hardened'.

Another mantlet consideration is that the extreme edge angles would not allow penetration. Even the 17pdr APDS would ricochet (mycenius). The need for a round to get at least half its diameter into the mantlet needs to be considered. The point of the AP round must be able to engage the armor to penetrate. Many hits along the upper inches would just direct the round off into space (or towards the driver/radio-operator compartment for downward ricochets).

[ September 19, 2004, 06:24 PM: Message edited by: Mr. Tittles ]

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Originally posted by lorrin:

Do you have the net address of the standard ordnance catalog?

Thanks.

Lorrin

I downloaded it from here. Its the late 44 version and the 75mm solid shot is not even mentioned for the sherman and 1918 guns.

http://www.carlisle.army.mil/cgi-bin/usamhi/DL/showdoc.pl?docnum=712

[ September 19, 2004, 06:42 PM: Message edited by: Mr. Tittles ]

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The Mycenius data clearly shows that the US 90mm M82 round was inferior to the M77 solid round prior to D Day. The in theatre testing during July showed they were using M77 rounds.

The USA catalog lists the 90mm M77 as having 4 in/20 deg penetration against face hardened plate at 1000yds. It lists 4.8 in against homog armor at same range/angle.

[ September 20, 2004, 12:53 PM: Message edited by: Mr. Tittles ]

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http://www.panzerdiesel.com/data/e/27p5_karo.html?SID=e688b03e16b0b83222d331b662a115b1

Heres a panther thats taken some hits.

The one hit on the hull barely gouges the armor. The one striking at the junction of the front turret armor and the side armor shows that bthis is a weakness in the interlocked german armor scheme. There might be a ricochet above the turret MG hole.

The mantlet appears to be very smooth in this picture. It does not have zimmerit on it. For a cast piece, would you expect such a smooth surface?

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These are my last words on the Panther mantlet business until I have better information on the British 6 pdr APCBC trials against the mantlet:

1. Failure of 76mm M62 APCBC against the Panther mantlet beyond 200 yards could be due to shatter gap, and no remarks would be found in the report because no remarks were made on any of the other failures.

76mm APCBC M62 penetrates about 123mm of RHA at 200 yards and 0 degrees, Panther mantlet center is 100mm case, so armor would have to put up 123% of flat rolled armor equivalance to stop 76mm hits beyond 200 yards. And that's on center area hits.

Ditto for 76mm M79 AP except the percentage is even higher for flat rolled equivalence.

2. The British trials with 6 pdr APCBC show that the Panther mantlet did not offer any unusual resistance values and the cast armor did not act like it was better than rolled armor. When I have more data the factors can be expressed numerically.

3. Curved mantlet armor may be more resistant than a flat plate, or it may be less resistant. Or it may offer the same resistance for similar impact angle and T/D ratio.

The British trials suggest that the Panther mantlet was not capable of stopping 76mm APCBC hits beyond 200 yards unless something else was occurring (like shatter gap), since the 76mm APCBC could outpenetrate 6 pdr APCBC against all sorts of armor.

4. The Isigny APDS rounds bounced due to excessive yaw which impacted the accuracy and penetration capability.

5. 6 pdr hits on the Panther turret anti-tank guns in Italy resulted in 6 pdr failures, which is contrary to the British firing trials. Difficult to explain, lots of possibilities (including subpar ammo).

There is what appears to be conflicting data here.

[ September 20, 2004, 08:44 PM: Message edited by: lorrin ]

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76mm APCBC M62 penetrates about 123mm of RHA at 200 yards and 0 degrees, Panther mantlet center is 100mm case, so armor would have to put up 123% of flat rolled armor equivalance to stop 76mm hits beyond 200 yards. And that's on center area hits.

The USA catalog lists the 90mm M77 as having 4 in/20 deg penetration against face hardened plate at 1000yds. It lists 4.8 in against homog armor at same range/angle.

These values are very close to each other.

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Originally posted by Mr. Tittles:

http://www.quarry.nildram.co.uk/Molins.htm

website with 6 pdr info.

We obtained most of our British penetration data directly from Bovington Tank Museum, so we know what we are using and have the background info for the tests.

We collected a set of ordnance board curves for 6 and 17 pdr APCBC, APDS, etc.

The John Salt Snippets provide a wide assortment of penetration stats.

Before using the info from Bovington or John Salt's Snippets we compared to actual shot-by-shot firing tests at a variety of angles.

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Originally posted by Mr. Tittles:

http://www.quarry.nildram.co.uk/Molins.htm

website with 6 pdr info.

The posted penetration data for 6 pdr APCBC fired at 790 m/s on the site you identified is not correct, and the actual muzzle velocity was 792 m/s. It is not equal to 68mm at 0 degrees and 500 yards (457m), and is not consistent with the Ordnance Board Curves.

A check on the 6 pdr APCBC penetration at 790 m/s vs at 830 m/s is to take the higher velocity penetration and multiply it by:

87mm x (790/830)raised to 1.43 power.

According to our data, the 6 pdr APCBC fired at 792 m/s would penetrate about 97mm vertical at 457m, and the 30 degree penetration would be about 78mm

The 6 pdr APCBC round fired at 831 m/s would penetrate about 104mm vertical at 457m, and about 83mm at 30 degrees.

So both figures for 30 degree penetration by 6 pdr APCBC at 460m look questionable.

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The British used a large number of different ballistic limits, so some variations could occur due to whether 50% of the rounds succeeded, or 80%, or one merely had to punch a small hole allowing light to pass as opposed to having 80% of the round pass through.

My data is keyed to 50% success where the round makes it through with most of its mass.

But 68mm/30 degrees/500 yards for the 790 m/s 6 pdr APCBC is way too low and may be a typo.

87mm at 30 degrees for 831 m/s 6 pdr APCBC seems high for rolled homogeneous armor, and could be the face-hardened figure or it could be for a lesser degree of penetration (like a small pinhole counts as a success).

Most British sources for 831 m/s 6 pdr APCBC have 81mm at 30 degrees and 500 yards for 50% success, so 87mm would be about right for 20% success but not 80%. Look through the John Salt WW II Penetration Snippets and don't rely on one source.

Our face-hardened figure for 831 m/s 6 pdr APCBC at 457m is about 88mm with 50% of rounds making it all the way through, so while the site you identified says the penetration is against machineable quality armor (homogeneous) at 80% success it may be a face-hardened figure at a lower success rate.

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