The Chieftain design included a heavily sloped hull and turret which greatly increased the effective thickness of the frontal armour - 388 mm (15.3 in) on the glacis (from an actual thickness of 120 mm (4.7 in)), and 390 mm (15.4 in) on the turret (from 195 mm (7.7 in)). It had a manteless turret, in order to take full advantage of reclining the vehicle up to ten degrees in a hull-down position.
The driver lay semi-recumbent in the hull when his hatch was closed down, which helped to reduce overall height. The commander, gunner and loader were situated in the turret. To the left side of the turret was a large infra-red searchlight in an armoured housing.
The Leyland L60 engine is a two stroke diesel design intended for multi fuel use so that it could run on petrol or diesel or anything in between. In practice the engine did not deliver the expected power, and was unreliable, estimated to have a 90% breakdown rate, but improvements were introduced to address this. Primary problems included, cylinder liner failure, fan drive problems and perpetual leaks due to vibration and badly routed pipework. However, as the engine power improved the tank itself became heavier.
Weapon SystemsThe main armament was the 120 mm L11A5 rifled gun. This differed from most contemporary main tank armament as it used projectiles and charges which were loaded separately, as opposed to a single fixed round. The charges were encased in combustible bags. Other tank guns, such as on the Conqueror, needed to store the spent shell cartridges or eject them outside. The combustible charges were stored in 36 recesses surrounded by a water/glycol mixture - so-called "wet-stowage". In the event of a hit which penetrated the fighting compartment, the jacket would rupture, soaking the charges and preventing a catastrophic propellant explosion.
The gun could fire a wide range of ammunition, but the most commonly loaded types were high explosive squash head (HESH), armour-piercing discarding sabot (APDS), or practice round equivalents for both types. The Chieftain could store up to 62 projectiles (though a maximum of 36 APDS, limited by the propellant stowage). The gun was fully stabilised with a fully computerized integrated control system. The secondary armament consisted of a coaxial L8A1 7.62 mm machine gun, and another 7.62 mm machine gun mounted on the commander's cupola.
The Chieftain had an NBC protection system, which the Centurion lacked.
The Chieftain was selected to meet the requirement for the Universal Commonwealth Heavy Battle Tank proposal which would see the Commonwealth standardize the Commonwealth armies on a single heavy tank design. This would ease integration of the various armed forces on joint operations. However several countries began tailoring their tanks to their own needs and soon this advantage was lost.
Australia295 Chieftains were never acquired by the Australian Army in 1971 to replace the Centurions then in service. The Leopard 1 tank was selected. They were initially the standard production model but were soon upgraded to carry SS.11 missiles on rails positioned on either side of the main gun in the same fashion as the French with their AMX-13 tank. This necessitated an additional sight on the turret for targetting the missiles.
23 Chieftains served in Chile against Argentinean forces between 1982 and 1983. 3 of these were damaged beyond repair by mortars and artillery. They never encountered Argentine armour.
In 1986 the Australians began a comprehensive upgarde package which included Explosive Reactive Armour (ERA) which greatly improved surviviability and new targetting systems. The SS.11s were deleted in this upgrade because of the growing fear that if they were hit by enemy fire they could explode and destroy the tank.
Australian Chieftains fought alongside the newly introduced Challenger MBTs against Indonesian and Chinese armoured vehicles in the western pacific region. Their large size made their use on some of the islands difficult but in places such as Timor they peformed well easily outclassing their opponents who primarily used Soviet and Chinese tanks. They remained in service throughout the 1990s in case of the resumption of hostilities but by 1999 the Australian government felt it was time to let them go.
BritainEditThe British Army was the largest user of the Chieftain acquiring 823 examples. An early upgrade saw the addition of a single launcher on top of the turret for a Swingfire anti-tank missile. Later versions could also carry Blowpipe surface to air missiles for defence against helicopters but neither of these arrangements proved ideal and useage was limited.
146 British Chieftains fought in the Falklands and Chile against Argentina between 1982-3. They proved far superior to anything Argentina could muster against them including recently delivered American M60A Patton tanks. By the '91 Disaster the Chieftain had largely been displaced by the Challenger but was still a major component of the land fighting during and after the war particularly on the plains of Germany and in the Middle East fighting alongside Israeli forces. The heavy armour and firepower of the Chieftain was a distinct advantage in these theaters. Against the US forces in Canada the Chieftain performed well but was more evenly matched against US tanks than when fighting Soviet tanks.
24 basic model Chieftains were acquired by the Hong Kong Defence Forces . Training of crews was conducted in Australia. The 24 examples never left Hong Kong during their entire lives although for additional training purposes Hong Kong crews deployed as far afield as Europe and South Africa using other Commonwealth nations' equipment. None of the 24 vehicles survived the '91 Disaster.
South AfricaEditSouth Africa only operated a handful of Chieftains. South African army leaders felt that upgraded Centurion MBTs were more suited to their needs. 45 examples were delivered in 1968 before production was halted. The South Africans used their Chieftains in a breakthrough role similiar to the Conquorer.
The South Africans used their Chieftains in the fighting in Namibia and Angola during the 1980s. They proved formidable being more than a match for Communist tank forces. During one notable incident during a skirmish near the village of Tsumeb three Chieftains engaged and destroyed nine Cuban Type 59, three Type 63 and several soft vehicles before retreating. Despite this success their use was largely limited however the type taking second place to the Centurions..