From: Employee@MilVeh.com
Date: Thu Aug 07 2003 - 20:31:45 PDT
The ubiquitous RPG-7 anti-tank grenade launcher can be
picked up for a mere $10 in most of the world's
trouble spots but is capable of destroying a tank and
killing its crew. When the grenade hits the tank, its
"shaped-charge" warhead fires a jet of hot copper into
the target at around 1,000mph. This is capable of
penetrating more than a foot of conventional solid
steel armour.
The new electric armour is made up of a highly-charged
capacitor that is connected to two separate metal
plates on the tank's exterior. The outer plate, which
is bullet-proof and made from an unspecified alloy, is
earthed while the insulated inner plate is live.
The electric armour runs off the tank's own power
supply. When the tank commander feels he is in a
dangerous area, he simply switches on the current to
the inner plate.
When the warhead fires its jet of molten copper, it
penetrates both the outer plate and the insulation of
the inner plate. This makes a connection and thousands
of amps of electricity vaporises most of the molten
copper. The rest of the copper is dispersed harmlessly
against the vehicle's hull.
But despite the high charge, the electrical load on
the battery is no more than that caused by starting
the engine on a cold morning.
In a recent demonstration of the electric armour for
senior Army officers, an APC protected by the new
British system survived repeated attacks by
rocket-propelled grenades that would normally have
destroyed it several times over.
Many of the grenades were fired from point-blank range
but the only damage to the APC was cosmetic. The
vehicle was driven away under its own power.
Prof John Brown, of the Defence Science and Technology
Laboratory, which developed the Pulsed Power System at
its R&D site at Fort Halstead, Kent, said it was
attracting a lot of interest from both the MoD and the
Pentagon.
With the easy availability of RPG-7 rocket launchers
"it only takes one individual on, say, a rooftop in a
village to cause major damage or destroy passing
armoured vehicles", he said.
But the use of electric armour, which will protect
against all shaped-charge warheads including artillery
and tank shells, would reduce the threat to zero.
> You are looking at a VERY BIG capacitor.
>
> The latent heat of vaporization (amount of energy to
> turn liquid metal to
> vapor) for metals is as follows:
>
> Lead 8.7 x 10 E 5 = 0.87 million Joules /
> Kg
> Copper 5 x 10 E 6 = 5 million joules/Kg
>
> Assume a bullet weighs about 25 g (<1 oz):
>
> Lead 0.87 x 10 E 5 x 0.025 = 21,750 joules
> Copper 5 x 10 E 6 = 125,000 joules
>
> A joule = 1 watt-second (1 watt for 1 second) so
> for:
>
> Lead a 22 KW generator would provide enough power to
> defeat 1 bullet/ second
> Copper a 125 KW generator would provide enough power
> to defeat 1 bullet/second.
>
> In reality, the efficiency would be less than 50%
> requiring a generator many
> times larger. Batteries are out of the question.
>
> That's the physics, folks.
>
> -John
>
>
>
>
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