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From: psl@interchange.ubc.ca (Paul Lakowski)
Newsgroups: sci.military.moderated
Subject: Re: WWII Armor types
Date: 28 Oct 2001 14:46:01 -0800
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cray74@hotmail.com (Mike Miller) wrote in message
news:<5dcb47db.0110271754.5bd4c309@posting.google.com>...
> OTOH, I could probably argue the Schurtzen would be a weight-
> efficient way to fragment and induce a tumble in a 14.5mm AP
> round.
>
> So I can form my conclusion(s), but I wouldn't trust them.
>
> Mike Miller, Materials Engineer
Well thats the whole point of the sheilds.There as mass efficent as
the equivelent in armor but its the post impact tumble rates and
decapping of APCBC ammo .Dr Elders paper showed that ~0.15d plate was
all thats needed to decap so 5-10mm plate would effectively decap
projectiles up to 33-67mm diameter, so it should still be effective
against 75mm shells.
BTW if anyones interested I can Email his paper to
them.
Here are some sample effects of yawed penetrators that doesn't include
the damage effects of the plates directly.
The results are as follows
Yawed impact of Steel Ogive AP shot [ 4:1 L/d ] at sub ordnance
penetration velocity produced Yaw as follows from tests.
Int. J . Impact Engng Vol 22- (1999) REVIEW Non Ideal Projectile
Impact on Targets ,pp 100-381 [pp212].
AP @ 800-900m/s
°YAW = % loss of pen
2° = 1% loss
4° = 2-3% loss
6° = 3-4% loss
8° = 4-6% loss
10° = 5-7% loss
20° = 10-14% loss
30° = 15-21% loss
40° = 20-28% loss
50° = 25-35% loss
The immediate post impact yaw of AP shot through thin mild steel
plates is ~ 4-12°,if these projectiles are given enough space to
tumble they could easly strike the main armor yawed at 60° or
more.Int.J.Impact engng Vol-19, pp395-414.
Tests on finite thickness of various metals struck by APM2 -7.62mm AP
shots [Rc 62 hard steel core] struck thin steel plates [ T/d 0.4] @
850m/s resulted in the penetrators shattered atleast into halfs every
time.Int.J.Impact engng Vol-25 pp423-437.
Tests on mild steel chains immersed in epoxy resin , struck by 0.30 &
0.50 AP shots [T/d ~ 1:1 ; chain fractional volume 0.2 ], showed the
thickness effectiveness of the panels ~ the similar to mild steel
plate in resistance [ 50% to 100% of mild steel 80 BHN].These studies
didn't look at impact on follow on plates so don't take into account
yawing etc.The average resistance should have been 0.24 Te but ended
up ranging from 0.21 to 0.42 Te.The movement of the chains in relation
to the penetrator , while being struck was credited with this
effectiveness.
Looking at the anti heat theory the previously mentioned standoff
penetration figures for steel liner shaped charges [ WW-II HEAT]
suggest that since the PZfausts warhead standoff was only 0.4 to 0.6
cone diameters stand off.Which means that any amount of spaced plate
should have increased the penetration substitally . These 'Schnerzen'
plates offered standoff distance of about 66cm {Pz tracks #4} which is
4.4 cone diameters for a Pzfaust. At these standoffs the penetration
should up 35-50% and not down at all.
The standoff on a bazzooka is ~ 2 cone diameters [J of Applied Phys
1948 Vol 19, pp575]and the penetration should be ~ 2 cone diameters
penetration and any increase should reduce this penetration to 1.3
cone diameters @ 9:1 standoff ~ 51cm which is still a penetration of >
3.5 inches RHA. Still more than enough to penetrate the side armor of
just about any tank in WW-II.
BTW I thought Speilberger reported no damage to the side hull plates
in the tests...." Firing tests utilizing the russian 14.5mm anti tank
rifle at a distance of 100m [ 90°] showed no tears or penetrations of
the 30mm side armor, when protected either by plates or wire mesh."