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To: sci-military-moderated@moderators.isc.org
From: psl@interchange.ubc.ca (Paul Lakowski)
Newsgroups: sci.military.moderated
Subject: Re: WWII Armor types
Date: 30 Oct 2001 23:17:25 -0800
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John D Salt wrote in message
news:...
> psl@interchange.ubc.ca (Paul Lakowski) wrote in
> news:de5bf54f.0110271532.871cbf@posting.google.com:
> [Snips]
> > "Journal of Battlefield Technology" Vol 1-1 pp 1 a article
> > was published on HEAT developement and standoff
> > penetration chart was published for Steel,Copper and
> > Aluminum cone shaped liners..
> [Chart snipped]
>
> Thanks for that: A cut-out-and-keep table if ever I saw one.
>
> Now this is where I get in well over my head on warhead and
> armour design, but I would guess that most WW2 HEAT rounds would
> use copper liners. I would further guess that 340 Brinell would
> be pretty close to the right hardness for German 30mm MQ plate in
> 1943 (on the strength of PRO document WO 185/118, DDG/FV(D)
> Armour plate experiments, if anyone cares).
>
> So the relevant line would be:
>
> Liner ------ 1.0 2.0 3.0 4.0 5.0 6.0
>
> Copper | --- 4.2 4.4 4.2 3.8 3.4 2.8 Vs 340BHN
>
> ...which means that an additional standoff of half-a-dozen
> calibres would have considerable benefits in protecting the main
> armour. Against the sort of HEAT weapon I'm thinking of, a 76mm
> gun or 66mm Bazooka, that means a couple of feet. How far are
> Schurzen typically hung from the main armour?
Actually John; Bazzooka and Pzfaust and PzSchreck warheads where iron
liner as where most german gun fired heat. Not sure about russians but
I think copper was too valuable to waste on warhead designs.
Pzfaust had ~ 0.4-0.6 Cd standoff while Bazooka was 2 Cd standoff so
the figures are about 3 Cd & 2.5Cd Vs mild steel which according to
Ogorkiewic HEAT penetration of mild steel [ ~ 100 BHN] should result
in a difference of ~ 2/3 so 3 Cds becomes 2Cd penetration for bazooka
into RHA . Which would be 5 inches of penetration , close to whats
quoted. Pz faust should do 2/3 of 2.4-2.6 or 1.6- 1.7 x 150mm =
240-250mm which exceeds the quoted penetration by 25-40mm . It could
be a spin on the warhead or the liner cone is not at as sharp an
angle.
But in a test of scaled Bazooka warheads in 1948 penetration at
standoff was tested and the increase in standoff that a Pz-IV side
skirts should offer ~66cm or ~ 10 cone diameters additional standoff .
By standoff alone the penetration drops to ~ 1.3 Cd penetration into
RHA or ~ 3.5 inches. More than enough to penetrate the 30mm side hull.
The 10mm mild steel plate should offer 2x 10mm x 0.67 = 13mm bringing
this down to 77mm penetration. Still more than a match for 30mm side
hull, even from 45° strike angle the standoff curve is about the same
[~ 3.4 inches of penetration ]while the plate resistance is up to 4 x
10mm x 0.67 @ 45° [÷ COS 0.7] = 38mm . Thus the penetration should be
~48mm or ~34mm @ 45°...just enough to penetrate.
But note that the same side skirts struck by a PzFaust warhead has the
opposite effect. The standoff goes from 0.4-0.6 up to 4.4 Cd standoff
[ 660mm ÷ 150mm warhead], and the penetration goes up by ~40% [roughly
1.6Cd to 2.3 Cd ], not down as in the case of the Bazooka.