Gun - vs- Armor penetration tables

[simovitch]

I have a question for anyone who knows about ballistic testing procedure.

Generally speaking, regarding the actual plate used for testing, does the penetration (mm) listed mean that a plate of that thickness was used, or that the projectile in question embedded in some generic plate at that depth?

Example below: did the 75mm Gun penetrate a 60mm thick plate from 457m that was sloped 30 degrees from vertical, or did the testing entity (lets say USA in the 30's and 40's)use a standard block of armor (sloped 30d) and measure the depth of the resulting impact to be 60mm deep?

[JudgeDredd]

I would've thought the latter was true.

If they used a plate of 60mm and it was penetrated, thay haven't actually found the definitive penetration of the projectile...only that it has gone through 60mm. They could've used 50mm, saw penetration. Used 52mm, saw penetration. Used 54mm, saw penetration etc...but I would've thought they would have used a BIG block of metal and then measured the penetration of the projectile.

They may even have shaved a mm or 2 off for margin of error (it could be possible that whilst the projectile penetrated 60mm into a 200mm block, is it not possible a 62mm block (not having all the extra thickness) would be penetrated by the same projectile under the same conditions?

I'm making an non educated guess, as you may have noticed

[carnifex]

The testing procedures are unique to the entity performing the test - you would need to examine the procedures from that particular test to determine their standards. For example, the current Department of Defense ballistic test for armor identifies two separate penetration standards. There is CP, or Complete Penetration, and PP, Partial Penetration.

3.24 Penetration, complete (CP). A complete penetration occurs when the
impacting projectile, or any fragment thereof, or any fragment of the test specimen
perforates the witness plate, resulting in a crack or hole which permits light passage
when a 60-watt, 110-volt bulb is placed proximate to the witness plate.

3.25 Penetration, partial (PP). Any impact which is not a complete penetration
shall be considered a partial penetration.

[GoodGuy]

ORIGINAL: simovitch

Generally speaking, regarding the actual plate used for testing, does the penetration (mm) listed mean that a plate of that thickness was used,...

No.
Say the Germans took a high performance 75mm gun (say the German Panther 75mm KwK 42 L/70), then they considered the penetration performances of comparable existing guns or identical gun designs (say a PaK barrel), most likely, and I guess they then computed (roughly) what penetration depth could be expected (probably taking into account the [muzzle] velocity), before commencing any live fire testing.
The test environment is quite important, means it really matters what material is put behind the test plate. If the material behind the plate is harder than the actual test plate, then it's more likely that a rather "thin" plate is being penetrated (well, physics :p). In other words, such a setup makes it somewhat easier for the round to penetrate, so the round will penetrate more armor as compared to a case where "softer" backing material is being used.
That's why today's penetration tests are standardized in a way that there's a certain backing material (forgot which one) projected to be used, in order to make results comparable. Did the Germans employ such standards? Or the US? You'll have to research that.

EDIT: If I am not mistaken, JENTZ points out that at least the Germans used 30° (from vertical?) as standard setup, plus they used the same types of what they called "homogeneous" armor plates, so that results could be compared.
Some sources indicate that these plates were of better quality, means like a type of reference plate. I am not sure whether that's true or not, as I think it was Jentz who pointed out that the steel grades (coming from the different foundries) for quality assurance and tests (yes even test shooting) were in fact samples, so it's hard for me to believe they conducted tests on "best" plates.
On the other hand, I have not read anything about German armor production/testing from other authors (if there are any who cover that topic).

http://www.panzerworld.net/75l70

http://www.panzerworld.net/armourpenetration

My personal guess is, that the US were less consistent there, means one or another field or lab test was commenced using vertical plates, it seems.

...or that the projectile in question embedded in some generic plate at that depth?

Well, for the Germans, see my ref. to the "homogeneous" plate above. Probably a plate of say 200mm or even more, to cover all possible results (say with Panther gun, KingTiger, or even prototypes like the PaK 80 L/54,8 [also dubbed PaK 44, K 44 or K 81] - this gun could penetrate 201mm of armor at 1000 meters [30 degrees]). The exact setup is unknown to me, you might find it in Jentz, and probably in his works or works from other authors for US procedures.

Example below: did the 75mm Gun penetrate a 60mm thick plate from 457m that was sloped 30 degrees from vertical, or did the testing entity (lets say USA in the 30's and 40's)use a standard block of armor (sloped 30d) and measure the depth of the resulting impact to be 60mm deep?

I've seen some shady references on the net that indeed suggested that with some tests the US were just interested to see if they could penetrate the frontal armor of a given enemy tank, so that they took plates (and an according thickness) that would indeed "just" simulate the front plate of let's say a Mark IV tank, or they even took an enemy tank (eg. field tests in France, 1944). Jentz and others may have shed some light on that speculation, I don't know whether the mentioned refs are just wild speculations or not, sorry.

[simovitch]

The exact setup is unknown to me, you might find it in Jentz.

That would be helpful but I don't have Jentz. I have researched dozens of website, forums and online sources and none can really answer this rather basic question.

The evidence seems to point to firing at witness plates of different thickness until "the definition of penetration" is achieved and recording that thickness and type of plate(s) at that range. I just need confirmation.[:)]

[Jeffrey H.]

Just from a physics and dynamics POV, testing with a thin plate or a thick block will yield different results. Also, as mentioned above the mounting of the specimen to be struck will have an effect.
 
As for a specific answer to this circumstance, I can't say.
 
 

[simovitch]

I think I found my answer. While the different countries used different definitions of "penetration" they all seemed to use many different thicknesses of target plate, and the criteria included the projectile passing completely, or almost completely through the plate.

USA, for instance:

[06 Maestro]

I assume that the tests would seek the maximum thickness of total penetration. To do otherwise seems to be a waste of effort by giving non pertinent results.

The last few mm of plate will give way much easier that in the center of the plate. I offer as evidence, "spalling". This is what occurs on the opposite end of the initial impact. An area larger than the diameter of the round will beak away (in many tiny pieces). It follows then that a projectile that could penetrate 60mm would not be able to reach that depth in a 100mm plate-or even a 65mm plate. How deep it could actually penetrate I have no idea, but it must be less. Even if it is 2mm less, what is the point of such a classification system? You could end up with weapons with a rated capability of 55mm penetration when those could actually penetrate 60mm-or something like that.

I can't site specific official standards for these types of tests, but I think actual penetration is the standard.

Ah, damn, I had a visitor that interrupted my reply for a little too long.

[bartholimew]

That depends on many factors for the projectile and plate, tensile strength and scaling. As a general rule thicker armor is more effective if it is softer. Pirana LAV on the other hand have armor thickness of only 3/8 inch and depend partly on the hardening effect of the thin armor to deflect the first shot. (plus angle of plates, composition etc.)

Keep in mind all this data pertains to 1st hit only within a designated splash radius...that figure is missing from the tables presented. The Density of the plates change after it is struck by a non penetrating round. With enough hits in the same vicinity, on the same plate penetration can and will occur. Had a good chuckle at the guy some time ago who stated a Panther could never be frontally KO'd by a Sherman M4A1 even after consecutive hits at 300m or less. Great articles below present a clearer picture.

www.arl.army.mil/arlreports/2003/ARL-TR-3038.pdf

http://www.navweaps.com/index_nathan/M79apdoc.htm

[Sarge]

Don’t forget “sloped “ angle can double the penetration thickness/value.

[GoodGuy]

ORIGINAL: bartholimew

Keep in mind all this data pertains to 1st hit only within a designated splash radius...that figure is missing from the tables presented. The Density of the plates change after it is struck by a non penetrating round. With enough hits in the same vicinity, on the same plate penetration can and will occur. Had a good chuckle at the guy some time ago who stated a Panther could never be frontally KO'd by a Sherman M4A1 even after consecutive hits at 300m or less. Great articles below present a clearer picture.

Well, then consider the picture of a Tiger that was shown in the "Tigerfibel" (manual that was put in each Tiger I), where that particular Tiger was hit by 227 tank rifle rounds, fourteen 52mm AT rounds and eleven 76.2mm AT rounds. The "hits in the same vicinity" have to occur in an area of say half of a foot wide, and it takes quite some hits. Imho, it's rather a theoretical approach that does not apply to real world environments anyways, (as tanks are moving, as there was the superiority of German barrels and optics, etc.), so that a Sherman would rather get to a Panther's side or rear (if he's really lucky), than score a penetration from the front. With the original gun mantlet design of the Panther, the mantlet even deflected shells into the driver/radio op compartment, killing that particular crew member, while the tank was still fully operational.

We've had the discussion about a Sherman vs Panther here in the general forum already, the Sherman would have to have hit the gun mantlet, in particular the rather vertical parts with 0°-10° degrees, an area that's like what ... probably less then 2 feet in size? (as the rest of the gun mantlet was curved - I think 40°). And then the shell still had to go through 110 mm of armor. Jentz pointed out that the probability to receive a hit at these parts was rather low (means extremely lucky), not just for the Tiger II, but also for the Panther. There are pictures of Panther turrets with a hole, but these are either from TDs (90mm) or from high calibre AT guns. There is footage showing a Pershing tank picking on a Panther in Cologne, which defended the square in front of the cathedral... It took a Pershing beast to punch through the turret (cutting the commander's legs in the process).

[bartholimew]

I see your point. A tiger can survive 14 X 52mm rounds plus 11 X 76.2 rounds? OK sure. The math in the links above would support that. The panther 82mm front hull plate at 35 degree slope will be eventually breached by a sherman pumpkin launcher. Every time the plate is hit it weakens at a molecular level, the 82mm becomes an equivalent to 81.79mm, next hit an 81.44mm equivalent and it gets more complicated because the effects of the slope are integrated to the lesser until the plate cracks.
If you take billions and billions of 22 cal pellets and fire them at a panther a couple of centuries later it will bore a hole in the armor.[:D]