Challenger 1 Main Battle Tank. Vol. I

Finding a Successor to the Chieftain
In 1966 the British had at last started to replace the venerable Centurion with their first Main Battle Tank, the Chieftain. The Chieftain would soldier on as a gun tank until 1994 and achieve reasonable overseas sales before being replaced by Challenger 1.

It sounds very simple enough but the birth of Challenger 1 was anything but simple, for apart from all the usual criteria that affect tank design, politics probably have sometimes more influence than most, it was certainly the case for Challenger 1.
Once a new tank enters service and the vehicle procurement program is running well, design priorities switch to its replacement. This was especially true during the Cold War, and much as the 1950s had yielded technological innovations in many types of weapon systems, the 1960s had also seen advances of cardinal importance to armoured fighting vehicle design.
The Chieftain entered service in 1966 and was slated for replacement by 1985, a service life it would exceed by nine years. In the case of the Chieftain the choice of a replacement was complicated by a weak national economy and repeated defence cuts. Much of the research necessary to develop a replacement consisted of paper studies while the Chieftain itself went through its lengthy teething troubles. One such study survives from February 1976 (conducted by the Ministry of Defence and carried out by two civilians, and a major from the Royal Artillery). It lists the options for a possible Chieftain replacement for use in the 1st British Corps area in West Germany in the 1980s. The following suggestions were listed as serious options for a new British Main Battle Tank.

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It must be borne in mind that these were only paper suggestions (although the FV4222 was an updated specification for the FV4211, a design worthy of discussion). The report did not really reach any fine decisions and was a paper exercise, but the options it listed show clearly that by the mid 1970’s a great deal had transpired in the world of tank technology, developments that had given awareness of the need for a Chieftain replacement some urgency.

The FV4211
It also shows that as late as 1976 the Ministry of Defence was far from specifying its new MBT by even basic design parameters. It is likely that with Royal Ordnance Factory Leeds busy with Chieftain production, a certain amount of consideration was devoted to keeping the replacement’s general layout along the same general design parameters. This is a potential explanation for Chieftain Mk.5 derived options in the 1976 list. The principal technological development that was not included on the Chieftain series was Chobham armour, an innovation developed in 1964 when the Chieftain design was already finalised and in production. Alternately known as codename Burlington and codename Dorchester, two versions of this armour were in advanced stages of development and ready to test fit to an MBT by 1969. Chobham Armour was a quantum leap forward in the protection of armoured vehicles, and remains the optimal means of protecting an MBT even 40 years later. The potential advantage for a British MBT protected with Chobham armour in a tank versus tank engagement was plain to see.

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In 1970 the Fighting Vehicle Research and Development Establishment (FVRDE) constructed an experimental tank based on Chieftain tank components at ROF Barnbow, the first AFV to use the new armour. This tank, the FV4211, mentioned in the list above, was a truly innovative departure from an orthodox battle tank of its generation, representing in many ways the first modern MBT as we currently define it. The FV4211 was often known as the Aluminium Chieftain, and it was built using available components with a composite welded aluminium hull and turret. The use of aluminium was very much in vogue for the construction of lighter vehicles at the time and the FV4211 was the first MBT built on this basis. A welded aluminium hull and turret offered advantages in both in cost and weight. It was of a similar layout to the Chieftain both inside and out and utilised the same 120mm gun and 7.62 GPMG machine gun armament (and employed the L60/TN12 powerpack).