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Armor penetration of HE shells

Posted: Wed Jan 08, 2014 12:14 pm
by Francis Marliere
Gentlemen,

please forgive me to open here a can full of worms but I wonder about the armor penetration of HE shells.

I have read at http://www.navweaps.com/index_nathan/Pe ... _index.htm :

"According to Nathan Okun, a nose-fuzed projectile would penetrate 0.2 calibers of homogeneous ductile plate (obliquity not important when filler explodes in most cases) or 0.3 calibers of a face-hardened KC-type plate. Thus a typical 5” gun firing a nose-fuzed projectile would penetrate 1.0” of homogeneous armor or 1.5” of face-hardened armor throughout its range, with most of the penetration from the explosive force of the burster rather than kinetic energy."

While I have great respect for Mr Okun's expertise, I am a bit surprised for two reasons.

First, the difference in deck armor penetration appears very low between AP and HE shells.
According to http://www.navweaps.com/Weapons/WNUS_16-50_mk7.htm a USN 16"/50 AP shell penetrates 3.9" of deck armor at 20.000 yards, which is rather close to the 3.2" (16" x 0.2) that the HE shell is supposed to penetrate.
The numbers are even stranger for 8" guns (http://www.navweaps.com/Weapons/WNUS_8-55_mk9.htm). The HE shells penetrate 1.6" of deck armor while the AP one defeats 1.5" at 17.600 yards and 2" at 21.200 yards. Hence at battle range HE shells perform as well as (or better than) AP ones. I may be mistaken but that sounds strange for me.

Then, another article by Mr Okun (http://www.navweaps.com/index_nathan/Mi ... scarmr.htm) shows a formula which gives different results. For most circumstances, HE shells are said to penetrate 0.156 of STS plate (plus a small bonus for the projectiles which keep a high velocity).

Thank you for any help,

Francis Marliere

Re: Armor penetration of HE shells

Posted: Wed Jan 08, 2014 7:48 pm
by tommy303
You might be missing the essential point that an AP shell is designed not only to pierce armour plate, but to carry on past the plate into the interior of the target and detonate its payload inside where it will do the greatest amount of harm. While the contact detonation of an HE shell might blow a hole in nearly the same amount of deck armour, the majority of blast and splinters are on the outside of the target structure and causes comparatively localized damage behind the plate.

Re: Armor penetration of HE shells

Posted: Wed Jan 08, 2014 9:09 pm
by Thorsten Wahl
here you are
Splitterwirkung.JPG
Splitterwirkung.JPG (60.21 KiB) Viewed 6912 times
Image3.jpg
Image3.jpg (70.31 KiB) Viewed 6912 times

Re: Armor penetration of HE shells

Posted: Thu Jan 09, 2014 9:05 am
by Francis Marliere
Thorsten,

thank you very much for the documents.
However, I don't speak a single word of German. Could you please explain them a bit ?

Thanks a lot,

Francis Marliere

Re: Armor penetration of HE shells

Posted: Thu Jan 09, 2014 2:42 pm
by delcyros
It says that 17mm Wh armour material (barely) offers some degree of protection against lateral fragmentation of 150mm HE nose fused projectiles.
-or that 28mm Wh are required to protect from 283mm HE nose fused, f.e.

However, distance to burst is unknown and keep in mind that Wh material in this thickness usually is treated much harder and better suited for fragment protection than US aequivalent STS steel in this thickness.

Sometimes people make this mistake stating that german Panzer had face hardened armour. That has only been done experimentally. Face hardening was applied only to thicknesses larger than 4". What they had was thin plates treated homogeniously to very high hardness levels of acceptable ductility. If they were sampled, the hardness was found to be large enough to believe it was face hardened, but that´s strictly incorrect as it was hard on both sides.

Re: Armor penetration of HE shells

Posted: Tue Jan 14, 2014 7:54 pm
by RobertsonN
Regarding the extrahard Wh splinter armor for, e.g. splinter bulkheads, was this material classified as Wh (UTS 85-95 kg/mm2) or was it Wotanstarrheit as used in AA directors or something else?

The finding that base-fused HE had a splinter penetration effect intermediate between nose-fused HE and APC seems different from British pre-WW1 tests which showed that CPC (powder filled) had a greater splinter effect (at least as far as penetration is concerned) than Lydite-filled HE,

Neil Robertson

Re: Armor penetration of HE shells

Posted: Thu Jan 16, 2014 12:28 am
by Byron Angel
RobertsonN wrote:Regarding the extrahard Wh splinter armor for, e.g. splinter bulkheads, was this material classified as Wh (UTS 85-95 kg/mm2) or was it Wotanstarrheit as used in AA directors or something else?

The finding that base-fused HE had a splinter penetration effect intermediate between nose-fused HE and APC seems different from British pre-WW1 tests which showed that CPC (powder filled) had a greater splinter effect (at least as far as penetration is concerned) than Lydite-filled HE,

Neil Robertson

..... My understanding of the Projectile Committee test results is that the difference lay in the differing explosive characteristics of lyddite versus black powder. The explosion of the lyddite burster in the WW1 APC would blow apart the projectile body into a very wide fan (140-180deg) of numerous but relatively small (fist-sized from photos) fast moving fragments, excluding the projectile nose which appeared to come off in a single large lump. OTOH, the burst of a CPC powder filled projectile produced a narrow cone (20-40deg) containing a small number (perhaps less by several orders of magnitude judging from photos) of relatively slow moving but very large fragments whose inertia would carry them through successive light bulkheads deeper in the ship.

Think akin to the difference between a modern HE shell and an old black powder charged shell of the horse and musket period. The modern shell will burst into several hundreds of fragments, while the black powder shell would break up into perhaps 10 or 15 large and heavy fragments.

B

Re: Armor penetration of HE shells

Posted: Fri Jan 17, 2014 7:55 pm
by Thorsten Wahl
General construction regulation - delivery instructions for armor material
(MDV 147 Allgemeine Baubestimmungen I Nr. 47 Liefervorschrift für Panzermaterial)
Wotan weich, hart, starr were only defined by minimum physical properties of chromium nickel molybdenum/chromium molybdenum steels the basic difference is heat threatment
note the mentioned the proofing conditions for the determination of the material properties
follow link
https://drive.google.com/file/d/0B12aaM ... sp=sharing