DEVELOPMENT OF CHIEFTAIN

Chieftain entered service in mid-sixties. It replaced both Centurion and the heavy tank Conqueror. It became what is now called a "Main Battle Tank".

Before Chieftain, British Army used to have all sorts of different types of tanks, each serving a different purpose. There were heavy tanks, medium and light tanks, infantry support tanks and a few more. It made perfect sense as long as the front did not move too much. This was based on the WWI experience. However, during WWII things looked somewhat different. Tanks had to advance fast which meant they could not be very heavy. They also had to face mighty opponents which also meant they had to carry a bigger gun.

One of the most successful British tanks of WWII was Centurion. It didn't see much action as it entered service just before the end of the war. Centurion is said to have been an equal opponent to German tanks. I guess it is easier to fight Panthers and Tigers after they have been bombed by the RAF. Nevertheless Centurion later proved to be very successful and was supplied to many armies in the world. From Sweden, Israel to Australia.

When WWII ended, Western Allies faced even a mightier enemy. Back in the late 40-ties the Soviet Union used, what many consider the best tank of all times - the T-34. The T-34 wasn't the prettiest, it didn't carry the biggest gun. Surely it wasn't the most reliable either. It did have, however, one distinct advantage - there were many of them.

The design of Chieftain began with setting up requirements. The new tank was to be called a 'universal tank' and it was to combine mobility of Centurion and fire-power and protection of Conqueror. It was therefore not to exceed 45 tonnes and was to carry a 120 mm main gun. It was to have a crew of four, a traditional layout for British tanks and it was to have reliable engine and transmission. This looked really good on paper. Unfortunately the first thing the British do whenever they come up with a simple and effective plan is they sit down and say: "Well then, we have a good plan. Now, what can we change?" And they did...

Chieftain started gaining weight even before the first vehicles were available for trials. From the original 45 tons it soon grew to 50-something. It also became obvious that at that weight, the engine will be well underpowered.

When designing a new tank, armies usually select a well-proven, reliable and simple engine. This ensures uncomplicated maintenance and good availability of parts. The British Army on the other hand selected for it's new tank an engine that originated in an aircraft. Leyland L60's comes in straight line from a WWII German Junkers aircraft engine.

According to NATO's directive all allied tanks were to be equipped with multi-fuel engines. The theory was that when allied tanks were advancing through Eastern Europe (or perhaps withdrawing in an orderly fashion), they could refuel from various sources, such as: petrol stations, oil depots, even fish and chip shops. As a downside this also meant that such engine had to be very complicated, difficult to fix and maintain. Soon all allied armies abandoned the idea and went back to good old diesel engines. Except for the British of course who stuck to their multi-fuel L60.

Another source of concern was Chieftain's transmission. TN12 is a semi-automatic gearbox with 6 forward and 2 reverse gears. Gears are selected using a foot-operated gear selector. The gearbox is linked to the main engine by a centrifugal clutch which activates at 400+ revolutions per minute. Downshifting can be manual or automatic.

Chieftain's engine and transmission was to become it's major problem throughout it's entire life undermining customers' confidence in British armour. None of the modern British tanks was able to repeat Centurion's export success. In fact, none of them sold in any noticeable numbers.

First Chieftains started arriving to units in 1965. The new tank was designated FV4201 and became the first MBT - Main Battle Tank in the British Army. Chieftain was upgraded several times with each major modification bringing a new mark. First Chieftains used by the Army was Mark 2, the production model was Mark 5 and the final upgraded model was Mark 11. Eventually most Chieftains used by the British Army were upgraded to marks 10 and 11. They are quite distinctive because of the add-on armour, called Stillbrew, attached to the front of the turret and in front of the turret ring. Mark 11 can also be easily recognised by the TOGS (thermo-optical gunnery system) camera and cooling unit attached to the left hand side of the turret and replacing the massive spot light used on previous marks.

Chieftains were eventually replaced by Challenger 1 MBT in the mid 80-ties. Some of them were converted to engineering vehicles, some ended up as hard targets on various firing ranges. Some were scrapped but quite a few were sold to private owners and museums.