IN THE first few days of the Yom Kippur war in October 1973, Israeli armoured units were attacked by Egyptian forces armed with Soviet-made anti-tank missiles. The Israelis “suffered wholesale destruction”, according to an American Army manual written soon afterwards to help counter the weapon in question. There was not much that could be done. As the American guide noted, the missile system—called Sagger by Western forces—could be carried in a suitcase, launched and steered using a joystick to hit a target 3km (1.9 miles) away. It would then penetrate any vehicle armour in existence.
Tanks had been destroyed with weapons carried by foot soldiers
before; America introduced its M1 Bazooka during the second world war.
But never had infantry so decimated armoured vehicles. Of Israel's
roughly 2,120 tanks, about 840 were destroyed during the 20-day war. The
era when “the tank was king” had ended, says Keith Brendley, head of
Artis, an American firm that develops protection systems for military
vehicles. Since then anti-tank munitions have become even more powerful,
but steel armours have improved little. Now, however, aided with new
materials and advanced sensors, a promising and eclectic array of
alternative and often ingenious new forms of armour is emerging.
Anti-tank missiles and rocket-propelled grenades (RPGs) penetrate
armour with a shaped charge. This explodes after the tip of the warhead
has sunk into the target. The brunt of the blast is projected straight
ahead, forcing a powerful spike of metal, usually copper, into and
through the armour. Using steel alone, few vehicles today could carry
enough armour to stop even an inexpensive RPG reliably.
Armour that explodes? Yes, really
To provide added protection, engineers have developed
explosive-reactive armour. This involves covering parts of a vehicle
with bricks of plastic explosives sandwiched between metal plates. When a
warhead hits the outer metal plate, the explosives underneath (also
specially shaped) detonate and force the sandwich to rapidly bulge as
the plates move apart. This can shear the armour-piercing spike into
bits, which are then less likely to pierce the underlying armour.
The Israel Defence Forces, shaken by their losses during the Yom
Kippur war, developed an early but effective explosive-reactive armour
that kept tank losses exceptionally light during the 1982 Lebanon war.
The innovation, however, created a new problem: the explosive bricks
generate shrapnel which can kill nearby infantry or civilians. As a
result, when America's Bradley and Stryker fighting vehicles are clad in
explosive-reactive armour they are not used in civilian areas.
Dynamit Nobel Defence, based in Burbach, Germany, is marketing a new
metal-free explosive armour, called CLARA, that limits the number of
such flying fragments. (The replacement materials are secret.) But no
army has purchased it. Defence officials with one western European
government have expressed concern that the extra protection to their
armoured-vehicle crews would come at too great a cost: even explosive
armours that produce less shrapnel could unacceptably endanger people
near vehicles. Peter Lehniger of Dynamit Nobel Defence concedes that the armour “may not be, from a moral point of view, a good trade-off”.
Engineers are finding ways to use less explosive material. OJSC NII
Stali, a Russian manufacturer, claims that by 2008 its reactive armour
required only a quarter of the amount of explosives used in its 1999
version, but provided just as much protection. The earlier model's
explosives detonated three to five microseconds after a warhead strike.
Such “sluggishness”, according to the firm, has been eliminated,
reducing the penetrating power of the spike. A danger, however, is that
faster-reacting, more-sensitive explosives might detonate accidentally
if hit by a bullet or another vehicle.
OJSC NII Stali and others are now developing non-explosive reactive
armour, known as NxRA. This uses “energetic” but non-detonating
rubber-like materials. Sandwiched between hard plates, they discharge a
rapidly expanding gas to absorb energy from a warhead. The gas pushes
out the external layer of armour so that it encounters the emerging
spike at a glancing angle. “Bulging armour”, as this system is sometimes
called, also increases the distance a spike must travel to enter the
Non-explosive reactive armours typically provide less stopping power,
but they have an advantage in countering “tandem charge” munitions from
systems like America's shoulder-launched Javelin and aircraft-launched
Hellfire missiles. Once a brick of explosive armour detonates, that spot
becomes more vulnerable to a second charge carried towards the rear of
the same munition and detonated about 500 microseconds later. Rubbery
non-explosive armour, in contrast, often remains partially intact.
So-called “cage” armour can provide additional protection against tandem
charges: metal bars (or even a strong fabric-like material) can make a
warhead's first charge detonate a couple of dozen centimetres away from
With a clean hit, the Russian-made RPG-7, the most widely used
anti-tank weapon, can sometimes penetrate more than 25cm of solid steel.
A more recent model, the RPG-29, is even more formidable. To counter
it, some European Union countries are developing electric armour. This
consists of two electrically charged metal plates separated by an
insulating layer. The idea is that when hit, the metal in a projectile
shorts the two charged plates together, forming a circuit and releasing a
surge of electricity which can break the warhead up.
Antoine Vincent, in charge of electric armour for the European
Defence Agency (EDA), says it has tested well against RPGs. A study by
BMT Defence Services, a British firm, notes that electric armour, being
lightweight, makes it easier to airlift vehicles. Even so, neither BMT
nor the EDA think the technology will be deployed soon. It has proven
difficult to rearm the metal plates from batteries fast enough to zap
the second charge of a tandem warhead. Some of the power-management
technologies being developed for electric vehicles may help on that
front. But, says Mr Vincent, electric armour still does not deliver
enough electricity to fry the metal in many kinetic-energy projectiles,
which destroy armour with their impact. An RPG warhead may eject a
copper spike weighing several hundred grams. Kinetic-energy projectiles
can weigh several kilograms.
Another approach is to use new materials. Steel armour performs well
against a powerful, broad blast, but if the energy is focused on a small
spot the metal can “melt like butter”, says an engineer with an
American manufacturer of armoured vehicles. To cope with that,
scientists have developed hard ceramic composites made from rubber and
epoxy resins. Unlike steel, they respond to tremendous pressure by
snapping. This action can break up a projectile or a shaped charge. A
ceramic armour called Dorchester Level 2, used on British Challenger 2
tanks, is reportedly at least three times as resistant to some strikes
as the same weight of steel.
The shockwave from a buried “improvised explosive device” (IED) can
tear into a vehicle or toss it over. SJH Projects, a small British
company, has developed a so-called “stone sponge” material that, fixed
to a vehicle's undercarriage, partially absorbs the blast. XPT, as it is
called, is a roughly 2cm-thick sheet of silica particles glued together
with a strong, heat-resistant resin. Small pores, visible with a
magnifying glass, channel the blast into mazes of micro-chambers. As
they are destroyed, the blast-energy is absorbed. It costs about $17,000
to protect a jeep-sized vehicle using XPT, and it only works once.
Steve Holland, the owner of SJH Projects, says NATO trials with
crash-test dummies show that the material dramatically reduces spine and
Does this mean armour is catching up with weapons technology? Hardly.
Armour is getting better, but weapons are getting deadlier. Consider
the Panzerfaust 3 (literally, “tankfist”), a shoulder-fired anti-tank
guided missile that flies at more than 720kph (450mph). After striking
its target, the exploding warhead shoots out a spike of copper at more
than 7km a second (25,200kph) with enough energy to blast through a
metre of steel, or any armoured vehicle used today, according to its
manufacturer, Dynamit Nobel Defence. (Like many defence suppliers, it
makes both weapons and anti-weapon systems.)
Moreover, some munitions can kill a tank crew without even
penetrating the armour. A high-explosive munition known as “squash
head”, fired by some British tanks, flattens a ball of plastic
explosives against an armoured vehicle. It immediately explodes,
transmitting a compression shock wave into the crew compartment, where
it strips off “spall”—flakes of metal, some the size of a frisbee—that
fly into occupants. Summing up the outlook for vehicle survivability,
Stuart Wheeler, an armour expert at the Tank Museum in Bovington,
England, says: “It looks grim.” Armour and vehicle designers, he says,
are still looking for a comeback.
Fight fire with fire
It may be on the way. On March 1st an RPG was fired at an Israeli
tank patrolling near the Gaza Strip security barrier. A radar system on
the tank tracked the incoming warhead, feeding data to a computerised
gun that shot it down with a small burst of projectiles. Israel plans to
deploy the system, called Trophy, more widely. Daniel Klein, an
armaments official at the EDA, reckons that the foiled attack, probably
the first of its kind, bodes well for defending military vehicles. An
additional benefit, he believes, is that Trophy and other so-called
“active protection” systems are lightweight. Some modern military
vehicles have become so heavy with armour that their manoeuvrability is
impaired and they are unable to use certain roads and bridges.
Iron Curtain, another active-protection system, has been developed
for American forces by Artis. It uses radar and optical sensors to
calculate the trajectory of an incoming warhead, and then intercepts it
with a projectile fired from a roof-rack (pictured). The impact causes
the warhead to combust before it hits the armour. Mr Lehniger, of
Dynamit Nobel Defence, says that Iron Curtain and similar systems might
be able to defeat his firm's Panzerfaust 3 missile. If so, the
achievement will be especially instructive to those who, decades ago,
considered protecting vehicles to be a doomed endeavour.