NG_Machines of War Tank
Transcript
00:00It's the silhouette that brings fear, 70 tons of armored firepower that can kill once every
00:14four seconds. In every corner of the world the tank has proved all-conquering, the iron fist
00:23that crushes armies and shatters morale. These mighty machines of war represent the culmination
00:33of a centuries-old struggle to perfect the art of mobile armored combat. Most generals
00:40would want to go to war with the tank.
01:04This is the 2nd Platoon D Company, part of the famed 1st Cavalry Division of the
01:09United States Army. We're riding out with them as they advance into the field at Fort Hood, Texas.
01:18They're aboard the Abrams M1A2, the culmination of a century of tank design.
01:30As this killer machine is put through its paces, we'll reveal how the tank was perfected over time.
01:37The gun has evolved into an awesome weapon that can take out a moving target three kilometers away.
01:44Warheads can now punch through 800 millimeters of steel.
02:07Tank armor has had to become strong enough to repel weapons like these, yet remain light
02:18enough to maintain a tank's speed and mobility. The effectiveness of this, the ultimate tank,
02:25was proven in 1991 when the Abrams first saw action.
02:29During Operation Desert Storm, over 1,500 Abrams tanks went head-to-head with 4,000
02:41Iraqi tanks under the command of Saddam Hussein. Despite the appalling conditions,
02:49the Abrams had the edge, according to Lieutenant General Paul Funk. We were on a 25 kilometer
02:56front and the winds were gusting up to 60 miles an hour. I mean, I called the cavalry squadron
03:02commander, the great Terry Tucker, and I said, what's your visibility like? He said, one to 300
03:07meters. But we know they're here somewhere. Right after that, boom, we slammed into it.
03:14I can still see that fight with the tracers, a pause, and then a tank turret going 60 feet in
03:21the air when all that ammunition and everything else blew up as a result of the hit by our
03:26tankers. In four days, U.S. forces wiped out most of the Iraqi tanks without losing a single tank
03:34crew member. The ease with which the fast-moving, fast-shooting Abrams hauls its 70 tons around the
03:43battlefield belies the humble beginnings of this quintessential war machine. In the early
03:521900s, engineer David Roberts was working to devise a way to drive a tractor across the
03:58muddy fields of eastern England without the wheels sinking in. He came up with the idea
04:06of chain belts fitted with wooden blocks. His tractor would lay out its own rolling
04:16road under its wheels as it moved along. This was the first steerable tracked vehicle.
04:23The tracks acted like snowshoes, spreading the load over a wide area, preventing the
04:31tractor from sliding and sinking into the mud. It wasn't hard to imagine these tractors
04:38carrying armor and guns instead of plows and hay bales. In the muddy battlefields of northern
04:49France, the First World War had ground to a spluttering halt. Troops were pinned down in
04:57their trenches by the murderous efficiency of the machine gun. What was needed was an
05:03armored tractor that could break the stalemate. But the tank that was born out of Roberts's
05:10invention looked nothing like the tank we know today, as military historian David Fletcher
05:16explains. This is a Mark 4 tank from 1917. The gun is in a sponson on the side. The main reason
05:26for this is that within the tank, the engine occupies most of the center of the vehicle. That
05:32in turn is due to the fact that the tank was designed with cross-country movement as its most
05:39important feature. The gunnery is really a secondary matter. The original purpose is simply
05:45to break the siege that had grown up around the lines of trenches and wire. Its job was to crush
05:51down the wire so the infantry didn't get tangled up in it, to keep down the heads of the machine
05:57gunners, kill them if possible so the infantry were not massacred, and then drive into and over
06:02the trenches. In other words, we'd put the ability to move over the ground, above the effects of
06:09firepower. 1917, the battle for Cambrai in northern France. The Mark 4 tank was an instant success,
06:18breaching the German defenses and shielding the advancing infantry from machine-gun fire.
06:28But the Mark 4 had an Achilles heel. Even though the tank moved no faster than walking
06:34pace, the crudely riveted track could break,
06:39leaving the tank a sitting duck. To understand why these early tracks broke, we've come to a
06:46modern tank track factory and asked engineer Jim Rowbottom to run a road test. We've built a
06:53section of track consisting of two different lengths, and this is made to the same configuration
06:59as track would have been built to in 1916. The track section is pounded on our rocky road for
07:09seven hours to simulate the wear from moving 28 tons of Mark 4 tank across the battlefield.
07:16If we look at the links that hold the two pieces of track together, and the state of the track pin,
07:22the pin has worn because it's been rubbing against the track link. This hole into which
07:27the pin was located has elongated quite a lot. The actual structure of the link means that it is
07:33quite incapable of a long life, and it has begun to fall apart, which is something that we wouldn't
07:42really want to happen. To minimise metal fatigue in modern track, shock-absorbing rubber bearings
07:50are fitted to the pins that connect the links. The rubber bearings also ensure a snug fit,
07:55reducing play and wear. Rubber pads are fitted to the underside of the track sections to dampen
08:04vibrations from the ground. Compared with the plodding warhorse of World War One, the modern
08:12Abrams is a thoroughbred. Its padded tracks can last the course for up to 3,000 miles and give
08:20the tank agility at speed, but it's taken almost a century to get to this point. Among the first
08:31tanks that could move a little faster than walking pace were these 1917 Renaults. Smaller
08:38and lighter than the British Mark IVs, they travelled around the battlefield with a top
08:42speed of just under five miles an hour. As with all tanks of the time, speed brought with it
08:49increased vibration. This placed enormous strains on the tank's components, not to mention its crew.
08:55This time the solution didn't come from farmers, but from the automobile industry. J. Walter Christie,
09:08an American engineer in the late 1920s, discovered that equipping each of a tank's
09:13wheels with independent suspension gave much more than a comfortable ride. These Christie
09:21prototype tanks were lightweight and agile. Without suspension, a tank can't move quickly
09:27over the rough terrain of a battlefield. Christie's design kept the track in contact
09:33with the ground and gave the tank superior handling. The US Army were impressed, but
09:40couldn't convince the irascible Christie to manufacture his tank to their specifications.
09:45When the communist Russians heard the Americans hadn't used the suspension system,
09:50they snapped up Christie's design for their new tank. This is the Soviet T-34, deemed by many to
09:59be the finest tank of the Second World War. Its most interesting characteristic by far is this
10:04suspension system, the method of springing, that enabled tanks to travel fast across country
10:10without completely wrecking the physical health of the crew. You ever get the chance to see a
10:16Christie tank on the move over rough country going fast? These wheels are literally bounding up and
10:22down quite independently of one another, but they're giving the crew a superbly comfortable
10:27ride for their day. More important than comfort was the additional speed that Christie's suspension
10:34gave to these tanks. Fully armed and laden, the T-34 could go into battle at 40 kilometers an hour.
10:41During the Battle of the Kursk in the summer of 1943, wave after wave of Russian T-34s proved
10:53too much for the German armored divisions. 60 years later and the bigger, heavier Abrams can
10:59cross the battlefield at over 65 kilometers an hour. As well as speed, it boasts the tank's
11:06second great asset, a powerful gun. This gun can launch deadly projectiles that kill at a
11:15range of three kilometers, but first you have to find your enemy and get them in your sights.
11:29In Operation Desert Storm in 1991, outnumbered U.S. tank forces were
11:34fighting on unfamiliar terrain in atrocious conditions and at night.
11:41But when it came to hunting down their targets, the Abrams had the technological edge.
11:51They had night capability, but we had the thermal imaging sights and capabilities,
11:58and so we could see about at night three times farther than they could.
12:02First contact this unit had with the enemy came in poor visibility at night.
12:08We got off the first set of rounds. The Iraqis were turning their turrets at the same time.
12:13We got off the first set of rounds, two-thirds of the Iraqi tanks were on fire. The next volley
12:18from our guns before they could fire, and all of them were dead.
12:22The Abrams thermal imaging system works by detecting any object on the battlefield
12:27radiating heat. Because it sees heat, not light, it can work in pitch darkness.
12:37Using his thermal imaging screen, the tank commander scours the horizon. An enemy tank
12:43appears as a hot silhouette. Its heat signal shines brightly on the screen. He passes this
12:49on to his gunner sitting in front of him.
13:02Our job is to work together as a team. We have a gunner's position here. He's the guy
13:08they call the killer in the hunter-killer team, and I am the hunter.
13:13They've located the target. To fire accurately and kill, the gunner needs to know the exact
13:19range.
13:20Fire and adjust.
13:25I have a laser range finder. When I see the target, I'll press these buttons here. It
13:30sends out a laser, which comes back and gives me a range to that target.
13:35The laser range finder is the last word in accuracy.
13:39It works by sending a laser pulse in a narrow beam towards the target and measuring how
13:44long it takes for the pulse to bounce off and return to the Abrams. As the speed of
13:49light is constant, it's a simple calculation for the onboard computer to make.
13:59Thanks to their laser technology, the Abrams crew can seek out and hit a moving target
14:06while travelling at full speed over rough terrain.
14:15Back to 1916, and in the tanks of the First World War, gunners had very little technology
14:20to help them in the mayhem of battle. They worked out the range to the target using trial
14:25and error.
14:36It was a technique passed down from their artillery ancestors of the 17th century.
14:44Guns were heavy and had to be manhandled into position. They were sighted by eye and range
14:50was guessed at.
14:54The noise and smoke of battle didn't make it any easier.
15:06We've asked artillery expert Colin Herriot to demonstrate how difficult and slow it is
15:12to aim a big gun and hit the target.
15:18Colin will try to hit this, a barn door, from about 100 metres away. His only aid is a homemade
15:25replica gunner's rule, the 17th century.
15:30This is the gunner's rule. It's a marked stick. I aim the bottom mark on the gunner's rule
15:36at the muzzle ring and aim it at what I want to shoot at.
15:43He'll keep firing till he finds the range and hits the target. It's a technique known as straddling.
15:50I'm going to try and hit this.
15:54He'll keep firing till he finds the range and hits the target. It's a technique known as straddling.
16:00Uncover your vent. Firing. Give him fire.
16:12We've overshot with that, so let's depress the barrel, see if we can get a considerably lower.
16:21We may fall short, we'll just have to see. That's how we straddle. If we do fall short,
16:27we know the next one, we just raise it a little bit more and we should hit the target.
16:33Firing. Give him fire.
16:43Seem to have kissed in front of the target there, so we've got to elevate just a little bit more
16:49to try and smack somewhere in the middle.
16:54Firing. Give him fire.
17:00Colin is a skilled gunner and working quickly, he can only fire two to three rounds a minute.
17:06Every telltale puff of smoke from his cannon gives away his position, making him a target.
17:13Fast forward 300 years and First World War tank gunners were just as slow at finding their range.
17:25I'm in the position of the starboard gunner. He's got this control arm sticking out here,
17:30which fits under the right armpit. His right hand then goes forward to this pistol grip arrangement under here
17:36and then he sets his eye to the telescope here. And now, using his body weight,
17:41he can elevate and depress the gun and even, to some extent, swing it round to track a target.
17:48The gun will fire out to about 7,000 yards. In fact, in anything more than 1,000,
17:54you'd be lucky to see anything, never mind hit it.
17:57Don't forget that the gunner can't see anything else, only what's through his telescope,
18:01so he's virtually got to be directed into whereabouts in his arc the target is in the first place.
18:11If the tank was to improve, the whole process of aiming and firing needed to be speeded up.
18:22The breakthrough came from the war at sea rather than the war on land.
18:32The British Royal Navy had used an optical system to calculate range for some time.
18:37It helped their gunners hit targets many miles away.
18:43But the range-finding equipment was big and heavy, not easy to fit into a turret.
18:52It wasn't till towards the end of the Second World War that this optical range-finding technology was made compact enough.
19:02Two lenses were positioned on either side of the turret.
19:06Each lens was connected to the same eyepiece by prisms.
19:11As the distance between lenses is known, the distance to the target is calculated using trigonometry.
19:20The gunner sees two images, one from the left, one from the right.
19:25Turning a hand crank pivots the lenses on either side till the images line up and merge.
19:39Better optics and range-finders meant tanks could hit targets at far greater distances.
19:45This encouraged tank designers to fit much bigger guns with more power.
19:50One of the most feared tanks of the Second World War was the German Tiger, with the most powerful gun yet mounted on a tank.
19:58It's an 88mm high-velocity gun that was originally designed for anti-aircraft work.
20:03And the British had already come to dread it in the desert.
20:07The Germans had enough flexibility in their system to convert their anti-aircraft guns into the anti-tank role with a gun like that.
20:15The sort of accuracy and hitting power it's got, you could take out other tanks at ranges where they cannot effectively take you out in return.
20:23That's its real asset, that big gun.
20:28Even as it destroyed everything it came across, the Tiger had one weakness.
20:33It couldn't fire its gun on the move.
20:36The gun's powerful recoil would have seriously damaged the turret and the tank.
20:41The gun's powerful recoil would have seriously damaged the turret unless the tank was stationary.
20:47The tank's crew had to halt, swing the turret, unlock and elevate, aim, then fire.
20:53By the time they'd done all this, they might have lost the advantage of their big gun and become a target themselves.
21:01Even tanks with smaller guns couldn't fire accurately on the move, simply because their barrels bounced around so much.
21:09Engineers had to come up with a mechanism that would keep the barrel steady, however rough the terrain.
21:20They began with this, a gyroscope.
21:23A gyroscope is a spinning wheel on an axle.
21:26Once spinning, it resists changes to its direction due to the forces created by the fast rotation of the wheel.
21:33If a spinning gyroscope is put into an environment that rolls around, it'll remain stable.
21:39Connect the gyro to the controls that position the gun, and the gun remains locked to the gyro.
21:45It's totally stabilised.
21:48The gyros in an Abrams tank keep the gun barrel steady, even as the tank crosses the roughest terrain.
21:57By fitting further gyros, it's possible to keep the gun locked on target, so it can fire on the move with accuracy.
22:06Now the tank had an accurate and powerful gun that could fire on the move, designers could turn their attention to what it fired, its ammunition.
22:16During the war, the tank was used as a weapon of mass destruction.
22:20It was a machine gun, and it was a very powerful weapon.
22:24It was a machine gun, and it was a very powerful weapon.
22:28By fitting further gyros, it's possible to keep the gun locked on target, so it can fire on the move with accuracy.
22:34Now the tank had an accurate and powerful gun that could fire on the move, designers could turn their attention to what it fired, its ammunition.
22:42During the Second World War, designers came up with an ever-growing arsenal of deadly weapons.
22:51One of these was known as the squash head.
22:54To demonstrate the deadly nature of this weapon, we've asked chemist and explosives designer Sidney Alford to set up an experiment.
23:04So, here we have 150 grams of plastic explosive.
23:09Sidney has welded steel armour to a metal plate, and bolted this in place on the side of a mock-up turret.
23:16I'm going to plonk it onto that target.
23:22His challenge? To destroy the inside of the turret without penetrating the armour.
23:28I'll plonk it a bit more.
23:30This plastic explosive he's patting into place will replicate the behaviour of the real squash head.
23:36That now represents the explosive, which has arrived inside a shell, which has squashed itself against the target.
23:48Inserting the detonator turns the harmless, inert putty into a lethal explosive that could blow most of the roof off a house.
23:56There's a melon sitting in for the crew.
23:59Goodbye melon.
24:03Firing!
24:05Four, three, two, one.
24:18Ah, here we are.
24:22At first glance, it looks as though Sidney's squash head has failed to do its work.
24:28But if you look round the back of the plate, I think I see one former melon, which is no more.
24:40And here, it's still warm.
24:45You would not like to share the inside of a tank with this travelling at, I would guess roughly the speed of sound.
24:54This scab of steel has been blasted off the inside of the armour.
24:59What I'll do now is unbolt this and we can have a good look.
25:03There we are.
25:10The squash head shell looks like any other as it leaves the gun tube.
25:15On impact with the turret, it sticks to the surface like a cow pat.
25:20The shock waves from the explosive cause little damage on the outside, but devastation on the inside.
25:27In the Second World War, the German Tiger quickly earned a reputation for being almost invincible.
25:35But it was severely compromised as a fighting machine.
25:41Its armour is thicker than virtually any tank before it, over 100 millimetres at the front.
25:47It weighs something in the region of 56 tonnes.
25:51As a consequence, it comes with all manner of limitations.
25:54To give an example, in order to bear this heavy load,
26:00extra wide tracks are needed and loads of wheels to press on the tracks.
26:05It is so heavy that it is endlessly stressing the engine and gearbox.
26:10You get this thing into really difficult country, you stand a pretty fair chance of having it completely disable itself.
26:17It was totally on the limit in terms of weight and power for anything that had been seen in action before.
26:25Tank designers needed to come up with lighter armour without losing any protection.
26:33One solution came from the Russian T-34, with an innovation that others were to copy, sloping armour.
26:41This piece of armour is 100 millimetres thick when positioned vertically.
26:46Angled at 30 degrees, the armour becomes twice as thick at 200 millimetres.
26:54To keep the armour at 100 millimetres thick, the tank had to be sloped.
26:59This was done in order to reduce the weight of the tank.
27:04The armour was twice as thick at 200 millimetres.
27:09To keep the armour at 100 millimetres thick only requires half as much steel, making the tank significantly lighter.
27:19The sloping armour of the T-34 had a downside.
27:23There was much less room in the front of the tank for the driver and the gunner.
27:27The solution? Smaller conscripts.
27:31On the plus side, some conventional shells simply bounced off.
27:44Sloping armour forced weapons designers to think again.
27:48They were looking for something to penetrate this new generation of protection.
27:53The struggle between ammunition and armour entered a new phase.
27:59In their quest to come up with more deadly weapons, designers looked back into history
28:05and surprisingly found the answer in a principle discovered in the 17th century.
28:12In the days of the big sieges, gunners observed they were losing power from their cannons.
28:18A cannonball had to be loose enough not to jam in the barrel.
28:23This allowed a lot of the force of the gunpowder to escape through the gap around the sides.
28:29Gunners devised an ingenious way to plug this gap,
28:33a tightly fitting wooden bung called a sabot, or wooden shoe.
28:38Well, I'm just fixing the sabot here onto the base of the round shot, or cannonball if you like.
28:45400 years on, we've asked artillery expert Colin Herriot to demonstrate what a sabot round does.
28:51It's just a piece of wood like that.
28:53When the cannon fires, if you've just got a cannonball in there, you lose a lot of power.
28:57With this lump of flat wood, the blast would hit it,
29:01and before this blows apart and disintegrates, in that millisecond that will give the initial impetus
29:06and will throw the cannonball further and faster.
29:10That was the theory. Colin has two attempts to prove it.
29:15He'll fire his cannon at this makeshift target.
29:18The first round will be a plain shot without the sabot,
29:21and the second will have his homemade sabot attached.
29:27For both shots, the distance to the target is the same,
29:31the amount of powder and charge and the size and weight of cannonball identical.
29:36It's a test to see which round has more power.
29:40The plan is to shoot a naked ball.
29:46Ball's going in.
29:49She's primed, and she's ready to go.
29:55Leaving.
29:57Dune fire.
30:05The first round hits the target, but it's very low down.
30:09There's the ball.
30:13She's come through there.
30:18Hit there and bounced off.
30:22Will the shot with the sabot attached do any better?
30:26Leaving. Giving fire.
30:43Look at that.
30:45Smack dead centre.
30:48Ball's gone through a good four inches of very strong Douglas fir.
30:53Not only does the sabot give it more power,
30:56but it does give it more accuracy.
30:59She's ploughed right through.
31:01Let's have a look round the back end and see what it's done there.
31:04The simple addition of a small disc of wood
31:06has effectively increased the punching power of Colin's cannon by a third.
31:10Come through pretty fast.
31:12We then have the second target over here.
31:15It's hit it so fast,
31:17it's almost as if the wood doesn't even know it's been hit.
31:20Right through.
31:26Late in the Second World War in 1943,
31:29a Belgian scientist working for the British
31:31took the sabot principle one step further.
31:35Ladislaus Permutter calculated that a smaller projectile
31:39would fly through the air much faster than a big shell.
31:43And if this projectile were made from a dense heavy material
31:47like tungsten carbide,
31:49it could penetrate even the thickest armour.
31:52But how to fire a small projectile from a big gun?
31:58Permutter's solution, a sabot that encased the projectile,
32:02increasing its girth, making it fit snugly into the barrel.
32:07No power was lost when the gun was fired.
32:10Armour expert Dr Paul Hazel.
32:13This is a relatively modern version of what Permutter invented in 1943.
32:19And what we have here is the penetrator,
32:22which is enclosed by this boot or this sabot,
32:26which carries this penetrator up the gun barrel.
32:30And when the whole assembly leaves the gun barrel,
32:33the sabot becomes separated by the air resistance
32:37that is offered to the sabot.
32:40And it's essentially like a very fast-moving crossbow bolt.
32:49As it sits in the breech,
32:51the sabot holds the projectile firmly in place.
32:55When the gun is fired, the assembly moves rapidly up the barrel.
33:00Almost immediately, the sabot peels away and falls to the ground.
33:10On impact, there's no explosion.
33:13The speed and density of the penetrator cuts through armour,
33:18causing complete devastation.
33:21This is an example of a target that's been struck by a 120mm sabot round.
33:26And here we have the type of projectile that was used.
33:30And as you can see around the outside of the target,
33:33we can see quite a significant amount of plastic deformation.
33:38In other words, the material has moved apart
33:41and has been permanently deformed as the projectile penetrates.
33:47These super-penetrating weapons inspired new concepts in armour.
33:51They experimented with special composites,
33:54using layers of ceramic and glass fibre sandwiched between steel.
33:59Some layers reduce the transmission of shock from squash-head rounds.
34:03Others provide resistance to new penetrating projectiles.
34:14The Abrams is clad in layers of composite armour
34:17designed to offer the best protection for its crew.
34:24In the first Gulf War of 1991,
34:27superior armour gave US forces another tactical edge.
34:34Lieutenant General Paul Funk.
34:37In Desert Storm, we knew we could not be penetrated
34:41in the frontal 60-degree arc,
34:43which is generally the best protected part of any fighting vehicle.
34:47We knew that we could not be penetrated
34:50at ranges of over 500 metres.
34:53So our idea was we were going to stand off at least 500 metres
34:57in any kind of a direct firefight with tanks or with their missiles,
35:01and we believed we could defeat them without losing our own crews.
35:05In fact, that proved to be true.
35:07Good armour meant Abrams' crews felt safe enough to get in closer
35:11then hit harder with their powerful gun.
35:15I can recall one battalion commander talking about his guy,
35:18calling him back, one of his company commanders,
35:21and telling him the RPGs are bouncing off the tanks up here.
35:25He thought that was pretty good, as he said,
35:28and I thought it was damn good.
35:30I mean, that's a great feeling,
35:32not one that you want to go out and try every day,
35:35but nevertheless, when you have that happen,
35:38you know, that gives you a little extra, you know,
35:41that gives you a little extra boost
35:44because you know your equipment's working the way it was supposed to.
35:48In the contest between ammunition and armour,
35:51more weapons were being devised
35:53with ever more devious powers of destruction.
35:56One of them was the shaped charge,
35:59first used in battle during the Second World War.
36:04This simple, hand-held, disposable weapon
36:07could immobilise a tank if you could get close enough.
36:21It quite literally changes shape to do its deadly work.
36:26It's better known today as the rocket-propelled grenade, or RPG.
36:32The shaped charge consists of a thin copper cone wrapped with explosive.
36:37On impact, the explosive is detonated
36:40and a powerful shockwave turns the copper cone inside out,
36:44creating a high-speed jet of hot copper.
36:50When the shell hits the tank and the explosive is detonated,
36:54it's this jet which literally cuts through the armour.
36:57We've brought together two experts in explosives
37:00to demonstrate the devastating power of a shaped charge,
37:04Manfred Helt and Sydney Alford.
37:07They'll fire a shaped charge at a stack of steel plates
37:10mounted onto the side of a scale mock-up of a tank turret.
37:16They stack up ten plates of steel, each five millimetres thick.
37:20That's 50 millimetres of armour.
37:23But the plates are angled at 30 degrees, like sloped armour.
37:27This doubles the thickness to 100 millimetres.
37:32Can you move it in, please?
37:34I'll leave it in three centimetres.
37:36What is the extent of exactly now?
37:38250 millimetres.
37:42Manfred and Sydney have allowed some distance
37:44between the copper cone of the shaped charge
37:47and the steel plate of the tank turret.
37:50They've allowed some distance between the copper cone of the shaped charge
37:53and the armour plates to replicate the way a real charge behaves.
37:57Better not tell him what's going to happen.
37:59No.
38:05A steel witness plate is hung behind the melon
38:08to record the penetrating power of the charge.
38:15Sydney inserts the detonator and retreats.
38:21OK, ready to fire.
38:24Firing.
38:25Four, three, two, one.
38:44So that charge behaved as a classic shaped charge.
38:49The piece of copper forming the cone,
38:51which started with a diameter of about 65 millimetres,
38:56has been squeezed down into a long rod,
38:59which was travelling exceedingly fast,
39:01going through the plate, through the melon
39:04and the other side of the tank.
39:09Remember the witness plate that we hung up inside?
39:12The melon has exploded.
39:15The jet has divided to give two holes.
39:20It's impressive and deadly.
39:25Sydney's small charge has blasted through 100 millimetres of steel plate.
39:31It has only a proportion of the power of a real rocket-propelled grenade.
39:36This is a PT-7 grenade, and quite typically,
39:39this type of warhead can penetrate approximately as far as the eye can see.
39:43Approximately 300 millimetres of steel.
39:46So if you take a look at this steel stack that I've got here,
39:49that means it can penetrate one, two, three layers of steel.
39:54Other variants of this type of warhead can penetrate anything up to
39:58between seven or even 800 millimetres of steel,
40:02so it's a very, very dangerous threat.
40:06But what can be done to stop shaped charges penetrating a tank turret?
40:13A young Manfred Helt went to the Middle East after the Six-Day War of 1967
40:18to test shaped charges against the armour of wrecked tanks left in the desert.
40:24He saw it as an opportunity to work with real armour out in the field.
40:34As he filmed his work, he noticed some tanks were less damaged after the explosion.
40:40He realised that his charge had detonated the munitions in the field,
40:44and that the explosion had caused the tanks to explode.
40:49Manfred had stumbled on something with amazing potential.
40:53He'd hit on what he called explosive reactive armour.
40:59Explosive reactive armour consists of a sheet of high explosive
41:03sandwiched between two steel plates.
41:06The explosive reactive armour is a thick layer of steel
41:10that is placed on top of the turret.
41:13Explosive reactive armour consists of a sheet of high explosive
41:17sandwiched between two steel plates.
41:20When a penetrating weapon hits it, the explosive layer detonates,
41:24forcing the two metal plates apart, repelling the incoming missile.
41:31Manfred Helt's design comes in the form of explosive boxes
41:35fixed to the outside of a tank.
41:37It's one of the more recent concepts in armour.
41:41To demonstrate Manfred's invention,
41:44we've asked him and Sidney Alford to fire another shaped charge.
41:51What we'll do now, we'll fire exactly the same charge,
41:55at exactly the same distance, at exactly the same target,
42:00but this time we now have a layer of Professor Helt's armour.
42:07One drawback with explosive reactive armour
42:10is that anyone outside the tank is in danger of being hit by flying shrapnel.
42:15Sidney has built a protective canopy to try and contain the fragments.
42:20Everybody ready?
42:22I'm ready.
42:23OK. Firing!
42:26Four, three, two, one.
42:37Oh-ho!
42:41Some of the steel plates look as though they've been penetrated.
42:44This is interesting. It's deflected the shock considerably.
42:49The actual penetration is, I think, much less.
42:55And my congratulations, Professor Helt's armour has worked very well.
43:00It hasn't come through.
43:02Now, there's a hole here,
43:05and that implies that the piece of armour hit it there and continued going.
43:12How far it went, I'm not sure.
43:16When the ten steel plates are laid out alongside those from the previous experiment,
43:21it's clear explosive reactive armour has protected the inside of the turret.
43:26The charge has only penetrated the top of the turret.
43:30The charge has only penetrated the top three layers of armour.
43:35I think that this is a pretty unambiguous demonstration of the effectiveness of reactive armour.
43:41It's pretty conclusive.
43:49Explosive reactive armour marked a watershed in the battle between weapons and protection.
43:56New technologies mean the future may lie with active armour systems
44:00that detect and detonate warheads before they get close to a tank.
44:10For designers, this is the Holy Grail.
44:13They could take away tonnes of passive heavy conventional armour
44:16and devise smaller, lighter vehicles.
44:26This would answer some strategists who feel that the concept of the tank is outdated
44:31and that modern armies need faster vehicles for rapid reaction forces.
44:38Do we need tanks anymore?
44:40I mean, that's for other people to decide, but we'd better think about it.
44:46This evolution has been an armour-anti-armour,
44:49mobile protected firepower against the enemy.
44:52I think you're always going to have a tank-like vehicle.
44:54Hell, let's not call it a tank anymore.
44:56I don't care, call it a horse.
44:59But I think what we have to have is,
45:01what is it that's going to fulfil the role that the tank plays today on tomorrow's battlefield?
45:09One proposal is this, the Stryker.
45:12It doesn't yet have active armour,
45:14but it's lighter and more mobile than the Abrams.
45:19It's available in many different versions
45:21and was designed to be airlifted into war zones.
45:32Stay low!
45:33Don't move!
45:34Stay low!
45:35Stay low!
45:36Stay low!
45:37Stay low!
45:38Stay low!
45:39Stay low!
45:40Stay low!
45:42Load it!
45:44Inside, a self-loading gun and a virtual battlefield on screens
45:48add to the complexity of the technology that can go wrong.
45:55Used in the recent conflict in Iraq, it was found wanting.
45:58Its armour couldn't keep out cheap and readily available rocket-propelled grenades.
46:05Once equipped with the extra protection needed,
46:07the Stryker becomes too large to be airlifted and deployed quickly.
46:20Over the last hundred years,
46:22the tank has benefited from countless improvements in technology
46:26and established itself as the supreme armoured fighting vehicle.
46:32The big question is, has it reached its limits?
46:38As the escalating battle between firepower and protection gathers pace once more,
46:43designers have plenty to keep them busy
46:46to keep this machine of war, the tank, in the front line.