The FV4201 Chieftain was the best tank on NATO's hand until the Leopard 2 was introduced
in 1979. With its success and shortcomings, it set the later Western main battle tank
design criteria in any respect. It waited against a possible Red Strom in Berlin and
defended Iran. Now, we are investigating the Chieftain, a legendary British knight.
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Despite its problematic mobility, the Chieftain was the best main battle tank with the highest
firepower and ballistic protection in NATO for nearly 15 years. Its L11A5 gun has paved
the way for the 120mm main gun as standard in the Western World. The story of the Chieftain
goes back to the late 1940s. By the rising of the Iron Curtain, the British
Army of the Rhine began to face the Soviet tank with big guns and thick armour, like
IS-3 and T-10. Against the possibility of happening of the unthinkable, the UK had to
develop better tanks. The first solution was to develop a 64-ton
monster with a 120mm gun, the Conqueror heavy tank.
Soon, the Western military planners realized that the heavy tank concept was obsolete.
So, the UK decided to develop a medium later, later defined as the main battle tank, with
a 120mm gun to replace both the Conquerors and the Centurions.
By evaluating the Korean War experience, the British Army prioritised firepower, and survivability
over mobility. The new tank's main gun's elevation angle and rate of fire had to be high. It
could engage the enemy at long range, from defensive positions. It had to be able to
withstand medium-calibre artillery ammunition. Thus, Leyland Motors began a study on a new
tank in 1956 and built three prototypes called FV4202 based on the Centurion Mk7. It has
a new turret without a mantlet and a reclined driver seat. The reclined seat design reduced
the hull's height and weight. The design without a mantlet made it possible to reduce the turret
height but increase protection. Also, it allowed a higher elevation angle for the main gun.
The FV4202 never reached the mass production stage, but the British engineers adopted the
new turret and hull design for the next tank, called FV4201 Chieftain.
The first prototype was completed in 1960. The tank was publicly unveiled in 1961. The
result of using these two new design criteria was highly satisfactory.
The Chieftain had a 280-millimetre front armour that was 80 millimetres thicker than the Conqueror's,
but it was nearly 10 tones lighter. During the later development process, the
UK worked with Israel, which had a priceless modern tank warfare experience. Israel intended
to produce the vehicle domestically. Even the UK sent two tanks to Israel for trials.
But after the 1967 Six-Day War, London changed its policy in the Middle East and this plan
was never actualized. In 1966, the British Army received the first
production variant of the tank, called Chieftain Mk 1, which had a 585 horsepower engine. These
tanks were used only for training, and their engines were constantly replaced with more
powerful and reliable ones. The operational variant of the tank was Mk
2 with a 650 horsepower engine. It was entered service in 1967.
The Mk 3 variant followed the Mk 2 in 1969, which had an improved auxiliary generator,
650 horsepower engine, dry-air cleaner element, modified cupola, oil-filled top rollers, axle
arms and track tensioner. The Mk 3/3 had a laser range-finder, modified
720 horsepower engine, and a new low-loss air cleaner system.
The final production variant was the Mk 5 with the 750 horsepower L60 Mark 8A engine
and upgrades to the NBC protection system. The Chieftain Mk 6, Mk 7, and Mk 8 were the
earlier variants brought up to Mk 5 standards. The Mk 9 and Mk 10 were Mk 6 and Mk 7 variants
with the Improved Fire Control System. Similarly, the Mk 11 and Mk 12 were the Mk
8 and Mk 5, which had the Improved Fire Control System. But, they also had the additional
Stillbrew armour, as well as the Thermal Observation Gunnery Sight and more advanced NBC filtres.
The Omani Mk 7Cs had the L20 sight incorporated the Type 520 laser range-finder. These tanks
were upgraded variants of the Mk 5s. Oman also bought 15 new-built Mk 15 designated
as the Qayd Al Ardh. The Iranian Chieftain Mk 5/5Ps had improved
mine protection and additional shock-absorbers on the rear station, as well as a 750 horsepower
engine. This country also ordered the FV4030/2 Shir
1 variant of the tank. The Shir 1 had the 1,200 horsepower Rolls-Royce CV12 diesel engine.
So, the hull's rear was reconfigured to accept a new power pack. It also had an improved
bogie suspension. But due to the 1979 Iranian Revolution, Iran cancelled the project.
In 1979, Jordan ordered this variant following the cancellation of the Iranian contract.
Different from the Shir 1, this tank, called Khalid, also had the Integrated Fire Control
System, Tank Laser Sight and the No 84 Day/Night Sight.
Iran also cancelled the FV4030/3 Shir 2 variant incorporating Chobham armour.
But, this tank led to the development of Challenger 1.
But, these cancellations have caused a problem between Iran and the UK. Tehran has demanded
the money paid for the programme. However, London rejects this demand, citing the sanctions
imposed on Iran. Currently, Iran is modernizing its Chieftain
fleet. This modified variant, called Mobarez, has a thickened underbelly mine armour and
more fuel capacity. Iran has also fitted new shock absorbers to the front and rear suspension
units of the tank. Other modifications include a laser range finder, a more powerful engine
and the addition of light amplifying and infra-red systems.
The Chieftain also has armoured recovery and repair, armoured engineer, and bridge-laying
variants. We may mention that one of the most notable
non-serial variants of the tank is the self-propelled anti-aircraft gun model with the Marksman
turret. The only front service user of the Chieftain
is Iran. Jordan still keeps these tanks in its inventory,
but they are in storage. Also, the Iraqi pro-government Shiite militias
have refurbished and used the Chieftain. Kuwait, Oman, and the UK are the former users
of the tank. The 4-person crew of the Chieftain Mk 5 consisted
of a commander, driver, gunner, and loader. Its hull length was 7.52 metres. The tank
was about 10.8 metres long, 3.66 metres wide, and 2.9 metres high. Its combat weight was
55 tons. The 750 horsepower Leyland L60 No 4 Mk 8A multifuel engine provided a maximum
road speed of 48 kilometres per hour. The range of the tank was 500 kilometres. The
Chieftain Mk 5 could negotiate 0.91-metre vertical steps, 3.15-metre trenches, and it
can ford to a depth of 1.07 metres. It had a 120mm L11A5 rifled main gun and two 7.62mm
machine guns. Thanks to its successful stabilization system,
the Chieftain had achieved 98 per cent first shoot to hit rate at a range of 1,500 metres
in trials during the British Army service. But, the actual fearsome part of its firepower
was its 120mm rifled gun. The L11A5 could penetrate the front armour of any Soviet tank
at long range. The 120mm ammunition were three pieces; projectile,
charge, and igniter. The combustible charges were stored below
the turret ring level and surrounded by a pressurised water/glycol mixture. This way,
in case of being hit, a possible explosion of the charges was prevented.
Using separated ammunition was a fact that made reloading easier for the small L15A5
armour-piercing discarding sabot munition, shortly APDS. The loader could wait by holding
the second of it on his lap while the gunner fired the first round. It increased the rate
of fire. The L31A7 high-explosive squash head round,
shortly HESH, could not pierce the armour, but it could defeat armoured targets by causing
spall, which could injure or kill a vehicle's occupants. The munition did not have only
good anti-armour performance but was also effective against fortifications and structures.
The tank could also fire armour-piercing fin-stabilized discarding sabot munition, shortly APFSDS.
But, the British Army was too slow to recognize the importance of this type of round. APFSDS
was superior to APDS. Even the trials in 1973 had revealed this fact, the Brits ignored
it. The misjudgement of the British Army has caused
a severe setback. Until Rheinmetall introduced its 120mm smoothbore
gun, the UK had dominated the tank gun market in the Western World.
The smoothbore guns were effective to fire APFSDS. By missing this development, the Brits
have given the superiority of the tank gun to the Germans.
Initially, the Chieftain had the 12.7mm L21A1 Ranging Machine Gun, which fired a three-round
burst of illuminating rounds to determine the enemy's exact location and range.
In the early 1970s, the Thales Optronics Tank Laser Sight Unit replaced the ranging machine
gun. With its laser sight, Improved Fire-Control System, and muzzle reference system, the Chieftain
could accurately engage the stationary targets at a range of 3,000 metres and moving targets
at 2,000 metres. On the left side of the turret, in an armoured
housing, there was a big infrared searchlight whose range was 1,000 to 1,500 metres.
The actual thickness of the hull's front arch, produced by the welding of the tensile and
cast steel plates, was 120 millimetres. But thanks to its slope, it provided a thickness
of 280 millimetres. Similarly, the front arch of the turret was
195 millimetres thick, but it provided 390 millimetres of thickness with its clever design.
In the 1980s, the British Army realized that the ballistic armour of the Chieftain was
weak against the shape-charged anti-tank munitions. So, the front arch of the turret was reinforced
by the Stillbrew composite armour. This armour, which was also effective against kinetic energy
munition, was applied only to the British Chieftains.
The early examples of urban camouflage were seen on the Chieftain tanks of the British
Army of Rhein. The mobility was the biggest problem of the
Chieftain. Its L60 multifuel engine was developed based
on the Junkers Jumo 204 engine of the BV 138 flying boat.
The engine was too weak for a 55-ton tank and highly unreliable. The early examples
of the L60 had a breakdown rate of 90 per cent.
Coolant leaks within the cylinder block were ordinary, which caused white smoke billowing
from the exhaust. It increased the risk to be seen by the enemy.
Over time, the engine constantly upgraded. But, as the engine power improved tank itself
became heavier. So, the Chieftain never gained a satisfactory power/weight ratio. Its Hortsman-type
suspension was also insufficient. The tank had acceptably good road performance. But,
its cross-country performance was far from good.
During the Iran Iraq War, it experienced many problems. For example, in the 1981 Operation
Nasr, which witnessed the biggest tank battle of the war, the Iraqi Army's 350 T-62s and
T-72s managed to destroy or capture 214 of 330 Iranian tanks, including the Chieftains.
The Iraqis lost only 45 tanks in the battle. Because of engine failure, many Iranian tanks
had been abandoned by their crews without a fight. Many immobile Chieftains had become
a sitting duck for the Iraqi tank gunners. But, we should consider the other facts in
the Iranian defeat. After the Iranian Revolution, the Mollas had
discharged or even prisoned a big part of the Iranian military personnel because they
had been trained by the enemies of the regime, the Westerners.
So, at the beginning of the war, the Islamic Republic of Iran Army had suffered a lack
of well-trained tankers and technicians. Also, its command structure had collapsed. In this
situation, Iran could not use its Chieftains effectively. Also, this tank was designed
in the 1950s. Of course, since then, the USSR had developed
new types of munitions against the thick armour of the Chieftain.
Initially, Iran had 894 Chieftains. When the war ended, only 60 to 200 of them were still
operational. Still, the Chieftain gained many victories
during the war. On many occasions, they hurt the Iraqis badly.
During the 1990 Iraqi Invasion of Kuwait, Saddam's tanks faced the Chieftains again.
In the 1990 Battle of the Bridges, 36 Chieftains of the Kuwaiti 35th Brigade managed to destroy
30 Iraqi tanks and hold the Iraqi offence for a while. After their ammunition ran out,
they withdrew towards Saudi Arabia. We may say after the Centurion, the brightness
of the British tanks in the international market began to fade out. But, the Chieftain
was still a shining knight of the crown. Its successful design features and 120mm gun have
shaped the future of Western tanks. It managed to reach a big market in the Middle East.
This tank fought well against all odds. So, the Chieftain has deserved to be a true legend.
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