History
The FV4201 Chieftain was an MBT (Main Battle Tank) used by the British army from the late 1960s
all the way into the 1990s. It set a standard in NATO for MBTs by introducing sophisticated
rolled
homogenous armour with an excellent 120mm rifled gun.
It was brought in to replace the Centurion tank. Despite being successful,
there was worry in the west of the Centurion having to fight the IS-3 and T-10, the bigger &
heavier
Soviet designs that went into service after WWII. Britain decided to create a superheavy tank
and
put a
large gun on it called the Conqueror. This tank was meant to work alongside the Centurion to
take on
the
bigger Soviet tanks while the Centurion would be able to deal with tanks such as the T-54 &
T-55.
What was soon realised as Centurion was being produced, was that the process to build its
replacement
had to start. They wanted to combine the firepower of the 120mm gun used on the Conqueror with
the
mobility and handling of the Centurion to create the ideal tank. This was part of the thinking
in
the
development of the Chieftain.
Timeline
Early Days
Despite the fact that the British invented the tank and used it to great effect during the final
years of WWI, further tank development in Britain was lost after the war due to a lack of money,
resources, & the conflicting demands of policing a world wide empire.
Germany, however, saw the potential of the tank after being on the end of many tank offensives
during
WWI. British tank designs lagged behind Germany during WWII in terms of firepower and armour
protection, with many suffering from mechanical unreliability.
The British army doctrine meant that it had different classes of tanks for infantry support and
offensive operations. By 1944, Fieldmarshal Montgomery and others were advocating for a
universal
tank to replace infantry and cruiser classes. However, the idea was not pursued until after WWII
had
ended.
Initial Development
The design of the universal tank began in 1946 under the designated name “A45”, just as the final
example of the cruiser tanks, the “Centurion” , was entering service with the British army. The
development of the A45 was slow & the concept of the universal tank was compromised when it was
found that it was too difficult to modify the design of the A45 for special purpose tasks such
as
amphibious assault or minesweeping.
The A45 project was abandoned in 1948 in favour of further development of the Centurion. The
Centurion by contrast was able to be adapted for roles envisioned for the concept of the
universal
tank.
The Soviet Threat
The development to a successor to the Centurion began in 1951 under the name “Medium Tank No 2.” The threat now was posed by the massed armies of the Soviet Union & the Warsaw Pact states. The Soviet block was equipped with thousands of effective medium tanks such as the T-34-85, and heavy tanks such as the IS-3 equipped with a powerful 122mm calibre gun. To counter this, western countries wanted to pursue a strategy of quality over quantity - to rely on a technological advantage over sheer numbers.
Initial Designs
However, in the early 1950s, the only NATO tanks producing tanks in large numbers were the
United
States and Britain. The two countries cooperated in tank design including a desire for a
standard
main armament. The British and Americans identified the need for a gun that can defeat 120mm of
rolled homogenous steel armour inclined at 60° at a range of 2000 yards.
Joint assessment was completed in 1956 and recommended a 120mm calibre gun with bagged charge
ammunition. At this point, the US and British went their separate ways for development as the US
army was not convinced with using bagged charge ammunition and preferred a smooth bore gun with
a
calibre of 90mm.
The L60 Engine
Leyland motors was appointed as the main design contractor for the new tank designated as
“FV4201”.
The hull of FV201 was decided to be a cast hull with well sloped armour with a cast turret front
with a roof and rear turret section that was rolled plate armour.
In late 1957, the standardisation committee of NATO determined that all NATO fighting vehicles
should be powered with an engine capable of running on a wide range of fuels from diesel to
petrol,
and even domestic heating oil.
In Jan 1958, a new engine was installed on FV4201 to conform with this new policy - called the
“L60”. The L60 multi-fuel engine proved to be the Chieftain’s main drawback. From the very
beginning, the Royal Armoured core held severe reservations about this engine, but these were
brushed aside. Britain's NATO partners found that the concept of a mulit-fuel engine was
impractical
and abandoned the idea and many adopted standard diesel engines. Only the British pursued this
concept with an unsuitable engine.
First Trials
Running trials began in early 1960 on roads with the engine speed governed at 1800 RPM. Attempts
to
run the engine on different fuels also proved troublesome. It was determined that it would take
approximately 8 hours to modify the engine to different fuels which proved impractical on the
field
under combat conditions. Failures were observed from excessive engine vibrations, and
overheating of
the gearbox to name a few.
Gunnery trials showed that the performance of the 120mm L11 main gun was very good. Although
successful, the trials demonstrated that there were still faults to be fixed before serious
production could begin, in particular with the engine and transmission.
Into Service
The FV4201 Chieftain was accepted into service in 1965 to allow production to start. Over the
next 2
years, only an extra 35 brake horsepower could be squeezed out of the L60 engine before it
equipped
the Chieftain Mk1 of which 40 were built. The MK1 was only used for troop trials & training.
The first service model Chieftain models, the Mk2, was delivered to the British army in 1966.
The
first tank regiment to be equipped with the new MBT was called the “11th Hussars”.
Teething Problems
The next major variant, the Chieftain Mk3, rolled off the production line in 1969. It featured an
improved 650 hp L60 Mk5 engine & many other enhancements. However, it still remained
underpowered
for a tank that now weighed 53 tons (~48000 kg).The L60 still having problems with unreliability
meant that many attempts were made to address this.
These problems were eventually fixed, but not before the reputation of the Chieftain’s engine
became
infamous. Under the engine modification program called “Totem Pole”, the engines of previous Mks
of
Chieftains were upgraded to the same standard of the final production variant, the Chieftain
Mk5.
The Mk5
The Chieftain Mk5 was released in 1975. It featured the L60 Mk8A engine of 750 hp with a top
speed of
30 mph. The Mk5 was the definitive Chieftain tank, weighing in at 55 tonnes - almost 10 times
greater than the original requirements.
Despite the terrible engine, at the time, it had the best MBT gun and the most heavily armoured
in
the world, until the introduction of the Leopard 2. The hull armour was welded & cast steel
which in
combination with its excessive thickness and extreme sloping made it almost impenetrable.
Stillbrew
The turret front was also very strong when it was first introduced into service. However, due to
many Chieftains being destroyed or disabled by T-62s during the Iran-Iraq War in 1980, forensic
examination was undertaken. It was concluded that the front of Chieftain's hull and turret was
inadequate. This led to the introduction of the Stillbrew armour package.
Stillbrew armour consisted of plates of steel-titanium alloy mounted over the cast turret of the
tank with a thick layer of rubber in between. In effect, it was an early type of composite
armour.
It was manufactured in England and used in early 1980 to upgrade the Chieftains as part of a
crew
protection package.
Further Variants
In British army service, variants of the Chieftain go all the way up to Mk11. Mk1 - 5 were the production Mks, while Mk6 - 11 were improvements on the production variants. Over 1000 improvements were done on the Chieftain during its service life. Mk12 and Mk13 upgrades were cancelled due to the introduction of the Challenger 1 in 1983.
Gloabl Experts & End of Service
The Chieftain was sold into the Middle East, the IDF (Israel Defense Force) initially helped
with
its
development as at one point they were planning on buying it. However, the British government
decided
that it was to side with the Arabs more than the Israelis at the time and didn’t sell to Israel.
This also led to the creation of the Merkava tank. The Chieftain was sold to a number of Middle
Eastern countries which include Iran, Kuwait, Oman and Jordan.
Overall, the Chieftain was a successful design despite its problems with the L60 multi-fuel
engine.
It served with the British army until 1996 with the introduction of the Challenger 2. It was
mainly
stationed in the Rhine during the Cold War ready to defend Germany against a possible Warsaw
Pact
attack.