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IMAGINE the soldiers of the future, warriors who will be equipped with body
computers, personal communicators and the very latest weapons and night sights.
With the help of military communications satellites and aircraft, these soldiers
will broadcast images of the battlefield to their commanding officers on the
other side of the world. At the same time they can download digital maps of the
surrounding area and view the latest reconnaissance images and videos as they
are taken by spy satellites and uncrewed spy planes.

But while the technologies of the digital battlefield are sweeping through
the armies of the Western world, a quieter revolution is underway in an area
much closer to the average soldier’s heart. At the Defence Clothing and Textiles
Agency (DCTA) in Colchester, Essex, materials scientists are developing combat
outfits for British troops of the future. And they have ambitious plans.

Global camouflage

Modern soldiers have to be prepared for chemical, biological and nuclear
attacks, as well as being protected against the more conventional hazards of
bullets, shrapnel and fires. They need to be camouflaged not only in visible
light but also in the infrared and radio regions of the electromagnetic spectrum
to keep them safe from night sights and radar. And their equipment must provide
acoustic camouflage, too: it must be quiet to put on and wear. Clothing must
keep soldiers cool during prolonged bouts of physical activity, and warm and dry
afterwards. And as if all this were not tough enough for the designers, the
garments must be weatherproof, durable, comfortable to wear—oh, and
washable too.

The DCTA’s past designs have used an onion skin approach to protect
troops—lots of layers, each one contributing a particular characteristic
or function. But with too many layers, a soldier starts to look like Michelin
man, and is about as handy on the battlefield. So the trick is to combine as
many functions as possible in a single layer. For example, modern military
underpants draw sweat away from the skin to keep the wearer dry, while holding a
layer of air in contact with the skin to act as thermal insulation. And the
linings of camouflage jackets are coated with particles of carbon that can
absorb the chemicals used in biological, nuclear and chemical attacks. By using
different combinations of layers, soldiers can equip themselves for battle in
conditions ranging from humid jungle heat to dry arctic cold.

So how few layers can you get away with? The British Army’s Combat Soldier 95
system, introduced last year, has cut the number to eight, thanks to advances
such as the high-tech underpants. But the next generation of clothes must have
fewer layers. The DCTA’s goal is to reduce the number to three in a clothing
system known as Crusader 21, which will replace the current outfits in 2005. But
squeezing all the functions of modern battledress and more into these layers
will be tough. “We must push clothing technology to its limits,” says Richard
Scott, the chief scientist at the agency’s science and technology division.

Perhaps ironically, the main threat to soldiers on the battlefield is the
weather, says Scott. “More soldiers have died from hypothermia and exposure than
in battle.” The DCTA is developing smart materials in which the level of
insulation can be varied so that they can be used all year round.

“Air is the major insulator in clothing,” says Colin Lowe, director of the
agency’s science and technology division. “So we’re looking at ways to change
the amount of air trapped in a single layer.” The simplest approach is to build
inflatable pouches into a garment. These would be blown up manually by the
soldier or by small pressurised cylinders of carbon dioxide. “It may even be
possible to develop sensors that monitor the external temperature and adjust the
level of insulation accordingly,” says Lowe.

Another possibility is to use artificial fur with fibres that rise and fall
according to the temperature. In the DCTA’s laboratories, Scott reaches for a
swatch of material of his own design. It is a 3D textile in which two
conventional layers are separated by strong fibres about 2 centimetres long.
With the fibres erect, the material provides as much insulation as a thin
duvet.

“But watch,” says Scott, holding up the textile so that the fibres are
clearly visible. Taking a firm grip on the outer layers he pulls them in
opposite directions, forcing fibres in between to lie flat. Collapsing the
fabric cuts its insulation by a factor of four to about twice the level of an
ordinary business suit. “In a real garment, you would apply the force using
Velcro or zips that pull the layers in opposite directions,” he explains.

The agency’s laboratories are now testing the material’s thermal insulation
properties, and Scott says a prototype garment will be evaluated over the next
year or two.

Comfort also looms large in the design of fire-resistant clothing, which in
the past has tended to be bulky and awkward. “For 99 per cent of the time,
soldiers don’t need it anyway,” says Scott. “What we’re looking for is a smart
material that sits passively in the clothing without interfering with comfort
and becomes heat resistant only when there is fire.”

The team is investigating a class of substances that swell and char at high
temperature to form a thick protective layer. “An increase in thickness of only
a few millimetres can provide up to 30 seconds of protection,” says Scott. “This
will save lives.” For longer-lasting fires there is little that clothing can do,
he explains, as the respiratory system becomes damaged by hot gases.

The “intumescent” materials being developed by the agency contain chemicals
that work rather like the ingredients in a cake. For example, baking soda
contains sodium bicarbonate, which decomposes during cooking to form carbon
dioxide. And because this gas is trapped in the dough, the cake rises. In the
context of materials science, ingredients that do the job of baking soda are
known as blowing agents, and the dough is replaced by carbonaceous materials
that trap gases and burn to form a protective layer of carbon.

In a cake, this process takes 40 minutes at gas mark 5. For a soldier trapped
in a fire it must be completed in a second or two. So intumescent materials also
contain catalysts to trigger the blowing agent at the desired temperature. But
setting the triggering temperature is far from easy. “You don’t want it to
trigger on a hot day or in the washing machine,” says Scott. “And if the
triggering temperature is too high you could end up protecting a corpse,” adds
Lowe.

Chameleon effect

Another way to protect against heat is by reflecting it away. By way of
demonstration, Scott picks up a piece of green material, pulls out a lighter and
holds the flame against it. Immediately, it turns white. He says the change
occurs in nanoseconds. When the flame is removed the material returns to its
original colour, unmarked.

This trick relies on a thermochromic dye with a molecular structure made of
several benzene-like rings. Its colour depends on the arrangement of double
bonds around each ring. As the temperature rises, a reversible reaction
rearranges some of the double bonds and the molecule loses its colour. The
problem for the design team is to produce the range of colours required by the
Army and fix them to the material. “We can get pastel shades and green but we
haven’t got the blacks or browns needed for camouflage,” says Scott.

Camouflage itself represents one of the toughest challenges on the modern
battlefield. The most difficult are radar camouflage and masking the soldier’s
thermal image at far-infrared frequencies. Thin metallised coatings can help
with thermal signatures. But a soldier covered in metal stands out like a beacon
at radar frequencies. “And then there are the face and hands,” says Scott. “This
one will be difficult.”

The team has ten years to get it right, but even then their work will not be
finished. Scott is already looking towards protecting troops from the next
generation of weapons, such as powerful adhesives and super lubricants that
temporarily immobilise soldiers. “But we don’t yet know how we’ll do it,” he
adds with a shrug.