Jagdpazner 38(t) "Hetzer" armour quality.

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Peasant
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Jagdpazner 38(t) "Hetzer" armour quality.

Post by Peasant » 26 Sep 2020 21:42

At around 18 min into this video Hilary Doyle remarks that the armour made for this vehicle was significantly inferior and that 60mm plates were equivalent to only 30mm of face hardened armour on Pz.III and 20mm side plates to the 14.5mm ones on the halftrack that was located nearby.

Now, I assume he was comparing the ballistic quality of Czechoslovakian made RHA to that of the german one, and it inspired me to look for more information about this topic. I know of no original documents, or references of any kind for that matter, describing ballistic testing of the armour of this vehicle so I wanted to ask, perhaps somebody here had a better luck researching this topic?


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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Mobius » 27 Sep 2020 00:10

In Spielberger's Light Jagdpanzer book the German's battlefield results indicated the front resistant to Russian 76.2mm shell fire. Also, one improvement that was needed was to add protection around the driver's visor because shells would slide up off the front armor and penetrate the glass there.
50% is like a mild steel value.

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Peasant » 27 Sep 2020 07:54

From Panzer Tracts No.9:

Image

So he may have been correct about the side armour plates.

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Contender » 27 Sep 2020 10:17

Why the side skirts then?

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Yoozername » 27 Sep 2020 18:46

Mobius wrote:
27 Sep 2020 00:10
In Spielberger's Light Jagdpanzer book the German's battlefield results indicated the front resistant to Russian 76.2mm shell fire. Also, one improvement that was needed was to add protection around the driver's visor because shells would slide up off the front armor and penetrate the glass there.
50% is like a mild steel value.
'He probably cited this report....

http://www.panzer-elmito.org/cazacarros ... -44_D.html

As a side note, there are late war reports that do mention the name Hetzer. More than likely originating among the troops long enough to be mentioned along with official name

http://www.panzer-elmito.org/cazacarros ... zer_E.html

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Peasant » 27 Sep 2020 23:21

From the "Catalog of Enemy Ordnance Material" describing Jg.Pz.38

Image

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by critical mass » 01 Oct 2020 12:27

ow, I assume he was comparing the ballistic quality of Czechoslovakian made RHA to that of the german one, and it inspired me to look for more information about this topic. I know of no original documents, or references of any kind for that matter, describing ballistic testing of the armour of this vehicle so I wanted to ask, perhaps somebody here had a better luck researching this topic?
I don´t think that Witkovitz was allowed to keep their own specifications of armor plate -seperate from the germans- at this late stage of ww2. If that is true, then the whole argument, while factually sort-of-true bears no relationship to the problem at hand.

Surface hardened 50-60mm plates were considerably more resistent than late ww2 RHA. That´s well estblished. The advantage comes from two sources: I) the resistence of the plate to plastic deformation and II) its ability to break up incoming shot. FHA cannot fail by ductile holing but by plugging/ discing. More importantly, surface hardened armor cannot flex under load.
However, these two aforementioned advantages only materialize at normal to low obliquity impact condition, where change of shape effects of the attacking projectile have the biggest effect on perforation. As You know, the armor plate of the HETZER was not vertical. It was employed in highly sloped installations all around. Under oblique impact, FHA is distinctly inferior to RHA in terms of resistence because the plate will always break up incoming shot, and thus inhibiting ricochet. A more ductile, softer plate can flex under the impact and let the projectile ricochet off, leaving a scoop.
I maintain tha nobody with a sane mind would use FH for HETZERs 60° glacis plate. It´s somewhat incorrect by Doyle to suggest that the HETZER had inferior ballistic resistence because it used softer Siemens-Martin-armor. It does not. All armor was made electric hearth or Siemens-Martin with Duplex process. These are distinctly superior processes than open hearth heats and produce much cleaner steels wiht less non-metallic impurities as noted by the british post ww2 assessment of german armor (pointing out that no such duplex processed heat was used for british armor plate, f.e.).

60mm FHA, tilted at 60° would have offered LESS resistence than 60mm RHA when attacked by 3" projectile. This is, as You might notice, the exact opposite Doyle´s statement that 60mm HETZER plate = 30mm FHA. It suggested to me that Doyle is not familiar with the basic correlations between metal properties and ballistic resistence. The superiority of FHA at normal impact was a non sequitur because of the requirement to fail by ductile modes in highly oblique conditions. Soft RHA plates were exactly what was needed to provide optimum ballistic resistence for the HETZER. I was little bit shocked by this reappearance of urban myths.
As You have noticed in this thread:
download/file.php?id=457569&mode=view
Lean alloyed, softer E19 plates were inferior at normal attack but slightly better at high obliquity than the somewhat harder and richer alloyed E22 plates in this thickness range. That beeing said, the hardness should remain high enough to offer sufficient resistence to plastic deformation but soft enough to to ensure that the plate fails by ductile plastic deformation.

Bottomline is that FHA plate was certainly better for Stug because its nose plate was near vertical but the RHA plate was better for HETZER because it resisted by deflecting the shot with highly sloped plate.

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Mobius » 01 Oct 2020 13:44

The Hillary Hetzer video has produced a lot of heat at warthunder.
I think I'll add CM's analysis to my comments there.
https://www.youtube.com/watch?v=ewG_hfrar7A

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Contender » 01 Oct 2020 15:54

Mobius wrote:
01 Oct 2020 13:44
The Hillary Hetzer video has produced a lot of heat at warthunder.
I think I'll add CM's analysis to my comments there.
https://www.youtube.com/watch?v=ewG_hfrar7A
Why bother? You'll be drowned out by children throwing around cringe opinions based off of "pop culture" :roll:
critical mass wrote:It suggested to me that Doyle is not familiar with the basic correlations between metal properties and ballistic resistance
I do not believe he or many other historians for that matter are familiar with armor penetration theory, metallurgy, or other more detailed aspects of WWII armor despite all the great work they have done in the past. Furthermore Youtube is all about the clicks & manipulating its algorithms for maximum exposure which motivates channels to produce hyperbolic click-bait style videos, accuracy is not the goal for any popular youtube channel rather it is grabbing people's attention which I suppose worked for them since this video is being discussed here. End point never trust e-celbs even if they were something else before.

-Good post btw.

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Yoozername » 01 Oct 2020 19:31

Since the AFV was so nose heavy, why would anyone design in a heavy slab of soft material? they could use a piece of real armor that was much thinner, and get equal protection with less weight. Not FH, just RHA in the reported 240 range.

I believe the extremely sloped armor was adequate against many weapons. Empirical evidence seems to indicate very few, if any, photos showing the plate penetrated. Much like the 20 mm plate on the StuG vehicles with it's even greater slope (20 deg). I believe the 20 mm plate on the StuG was FH?

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by critical mass » 02 Oct 2020 08:42

Its not working like this. There was no disadvantage by using 200 or 240 BHN glacis plates. And there is a definitive disadvantage employing >280BHN RHA plates at 60° when the attacking penetrator is supposed to be 1.0 cal/D or larger. The plate does not resist with its ultimate tensile strength under extreme oblique impact but with it´s elastic modulus, which for most steel armor is pretty much the same. What harder RHA does is tha the additional work hardening effects considerably increase chances of locally brittleness and thus, of early failure.

It´s more important to employ good cross rolled RHA plates with as little as possible impurities to not compromise the elastic modulus. There is a very flat, optimum hardness range at 60° depending on section thickness and the calibre of the attacking projectile.

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Re: Jagdpazner 38(t) "Hetzer" armour quality.

Post by Yoozername » 04 Oct 2020 02:57

Mobius wrote:
27 Sep 2020 00:10
In Spielberger's Light Jagdpanzer book the German's battlefield results indicated the front resistant to Russian 76.2mm shell fire. Also, one improvement that was needed was to add protection around the driver's visor because shells would slide up off the front armor and penetrate the glass there.
50% is like a mild steel value.
Yes, and armor and mild steel weigh almost the same. Why would anyone put weight on that does not offer protection? That would be my point.

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