John the Gingerbeer espoused:
It was pretty conclusively demonstrated in Desert Storm that bulldozed berms
of sand are pretty useless. But a proper tank fighting position is something
else entirely.
[Tomb] Given. But here's another point: Normal armour for tanks is in
the area of armour 3-5 (3d12-5d12). Adding a D6 ain't much. Perhaps
the discussion should be: How big of a round will be stopped by a prepared
tank fighting position (possibly concrete included)? By a quickly bulldozed
sand or dirt berm? By a rocky outcrop or ridgeline? I'm guessing the sand
berms might not stop 120mm rounds, but might
stop (just throwing some out) low-velocity 73mm guns, ATGMs, and 20mm
cannon. Thoughts?
Additionally, the ground type may play into it - I'm thinking being
behind a good ridgeline in Ontario on the Canadian Shield is like being behind
a couple of inches of dirt then solid granite! That'll stop or deflect a
pretty big round. And out West, if you get Prairie hardpan, it'll be almost
impossible to entrench without vehicles or explosives, but it would deflect
(once you had entrenched) far better than typical temperate climate earth.
> --- kaladorn@magma.ca wrote:
> stop (just throwing some out) low-velocity 73mm
73mm RCLR HEAT Round is stopped by:
36" Concrete 30" Granite 36" Rock 156" Packed Snow 100" Soil 50" Soil, Frozen
24" Steel 100" Wood, Dry 60" Wood, Green
> ATGMs,
120mm Sagger stopped by: 36" Concrete 30" Granite 36" Rock 96" Soil 48" Soil,
Frozen 24" Steel 108" Wood, Dry 66" Wood, Green
and 20mm
> cannon. Thoughts?
20mm antitank fire at 200 yds stopped by:
30" Brick Masonry
24" Non-reinforced concrete
18" Reinforced concrete 30" Stone Masonry 48" Wood 30" Sandbags filled with
brick rubble 30" Sandbags filled with gravel 60" Sandbags filled with loam 30"
Sandbags filled with sand, dry 60" Parapets of loam 48" Parapets of sand
> On 29-Aug-02 at 11:09, John Atkinson (johnmatkinson@yahoo.com) wrote:
These are numbers to stop the round. Does the imply that X% (say 30%) of this
amount will make it innafective versus heavy armour? Or is this the army
manual saying this is the minimum volume needed to make the rounds survivable?
> --- Roger Books <books@jumpspace.net> wrote:
> > 73mm RCLR HEAT Round is stopped by:
It's off a chart entitled "Material Thickness, in Inches, Required to Protect
Against Direct Fire HE
Shaped-Charge" on page 3-12 of FM 5-103 Survivability.
Just filling in some details:
> > > 73mm RCLR HEAT Round is stopped by:
The 73mm HEAT - the original RPG-7/SPG-9 round, and also the one fired
by
the low-pressure gun of a BMP-1 so it's not just RCLR - is impact-fused,
so simply hitting the berm detonates it. I suspect that John's figures are the
thicknesses necessary to stop the round from harming infantry behind the
obstacle - they're in the right ballpark for that, anyway.
FWIW this particular round isn't a threat to heavy armour. It can still
hurt modern tanks if it hits rear/top/bottom armour, and some places in
the sides, but that's because modern tanks usually don't have very heavy
armour
there :-/
> --- Oerjan Ohlson <oerjan.ohlson@telia.com> wrote:
> The 73mm HEAT - the original RPG-7/SPG-9 round, and
All HEAT rounds (AFAIK) are impact fuzed. And yes,
that is the point--sheetrock would stop the round per
se, the depth of the berm is to prevent it from injuring people behind it.
> John Atkinson wrote:
> >The 73mm HEAT - the original RPG-7/SPG-9 round, and
True. What I meant to say was that the 73mm only has an *immediate* impact
fuse - ie., doesn't have any *delayed* impact setting which would allow
it to penetrate some way into the berm, and even through thin brick
walls/concrete slabs, before exploding.
(For some reason I can only recall the Swedish terms for the fuse types and
have to make do with roughly translating them into English >:-( )
Other types of shaped-charge rounds do have this kind of delayed impact
fuse, though they're usually called "bunker busters" or "HEDP" or something
similar rather than "HEAT". Still, some (IIRC most!) of these rounds have
better armour penetration than the old 73mm :-)
Later,