George Forty on PzKpfw IIIH Front Hull Resistance

[rexford]

GERMAN TANKS OF WORLD WAR II, by George Forty, has an interesting passage on page 67 regarding the effective resistance of the PzKpfw IIIH front hull (32mm over 30mm, both face-hardened by many but not all accounts).

"from late 1941 many PzKpfw IIIs had extra face-hardened plates fitted, for example, on to the frontal armor, which defeated the 2-pdr and 37mm except at very short ranges. British tank gunners were complaining that their AP shot just bounced off the enemy tanks."

It is unfortunate that a reference is not given.

Anyway, 2-pdr and 37mm uncapped AP have 100m face-hardened penetration of 62mm and 65mm (vertical target armor), which suggests that 32mm/30mm on PzKpfw IIIH upper front hull was at least as effective as a single 62mm face-hardened plate, if not more so.

The British tests in Cairo during May 1942 suggested that 32mm/30mm resisted like a single 69mm face-hardened plate.

The penetration resistance figures from Forty's passage and the Cairo tests suggest that two face-hardened plates in contact did not lose resistance compared to a single face-hardened plate of the same overall thickness.

If the PzKpfw IIIH had carried 32mm/30mm homogeneous plates in contact, the effective resistance against 2-pdr AP hits would have been about 73% of the overall thickness, or 45mm. The reduction in penetration range due to using face-hardened armor instead of homogeneous would be 700m down to about 100m.

It's also worth noting that the Cairo tests showed that 32mm/30mm face-hardened had the same resistance regardless of projectile diameter, so scaling factors (T/D ratio) did not come into play.

[ November 07, 2003, 10:54 PM: Message edited by: rexford ]

[Mr. Tittles]

I recently dressed myself in my dark cape, put myself into a deep trance state and contemplated spaced armor effectiveness while in a deep deserted cave.

I ordered pizza but it never arrived.

One of the things I came up with (besides the rule never to eat cave spiders) is that spaced armor is most effective if the first plate struck is at a 45 degree angle downward, like the lower hull of a panther or T34, and the second plate is sloped back, like the upper plate of a panther/T34.

The advantage of this is that the AP round after penetrating the initial plate, is deflected upwards so that it attacks the next sloped plate at an even greater angle. This ricochet upwards is key. If the armor arrangement is viewed from the side, it forms a V shape.

[Mr. Tittles]

A secret revealed to me by a talking cave spider (yes, he had glowing eyes) was that the first plate will strip ballistic caps off the penetrator and the second plate should be face hardened.