Ancestors of the Challenger Tank (Chieftain 5/2, FV4211, FV4030)

[overscan (PaulMM)]

The Challenger tank was arguably born in about 1970 when the UK, impressed by the performance of their BURLINGTON (Chobham) armour, but concerned that a wholly new MBT would not be in service before about 1985, proposed the development of a near-term improved tank using some existing components of the Chieftain tank. This was given the designation Chieftain 5/2 for security reasons, but was really a whole new design, reusing existing automotive targeting and weaponry components.


Three different designs were initially presented, design 3 being the recommended one.

 

[overscan (PaulMM)]

The Chieftain 5/2 became FV4211, of which 9 were under construction and one completed, now on display at Bovington. This lead to FV4030, and hence to Challenger.

 

[JFC Fuller]

I was under the impression that FV4211 was little more than an experiment in using aluminium for MBT's with Chieftain as the baseline, the work of which would have probably ended up in MBT80? Indeed my understanding was that FV4211 was basically cancelled in 1972 when it was decided to join the FMBT programme with Germany (1972-1976).


Also I posted in this thread earlier and it has vanished:


Anyway, Challenger 1 was Shir 2 FV4030/3 as originally designed for Iran as part of a phased development programme that included Shir 1, basically just a Chieftain with the RR CV12 and the TN37 transmission used in Challenger. Gun and fire control systems were similar. Challenger only really existed because Vickers and RR Motors faced the abyss.

 

[Przezdzieblo]

The first idea was to add "Burlington" to Chieftains, but it boosted weight above 60 metric tons level. Then FVRDE/MVEE went with "aluminium Chieftain", aka Chieftain mk 5/2, which received designation FV 4211. Project codename - "Almagest". Abandoned circa 1972 when there was a decision to start FMBT jointly with Germans.

MBT-80 was planned as a pretty new tank, not just overgrown Chieftain. But during program various Chieftain-based test vehicles were used.

 

[JFC Fuller]

Przezdzieblo,

That was exactly my understanding of FV4211 as well. Challenger was basically the product of the Shir development programme undertaken for Iran and the ensuing cancellation of that programme following the revolution. Challenger was thus a heavily evolved but not fundamentally revolutionary Chieftain derivative whereas both FV4211 and MBT80 seem to have been intended to push the use of Aluminium in the chassis. Challenger / Shir 2 used the armour design of FV4211 but with a steel rather than aluminium hull.

Overscan,

This is the first time that I have heard that 9 FV4211 vehicles were under construction, I would love to hear more about the history of that programme. What is your source for 9 vehicles having been under construction?

 

[Abraham Gubler]

Overscan thanks a lot for this excellent information from the Burlington file... Interesting to see at those early days the UK referred to it as Burlington. Then of course the mafia of British military publishing told the world that this armour was Chobham armour… The rest is history but perhaps now those American adherents to using the term Burlington armour can rest vindicated.

 

[overscan (PaulMM)]

Well, calling a top secret armour technology developed at a facility in Chobham "CHOBHAM" would be like calling the Stealth fighter program "PALMDALE". BURLINGTON was a codename for the special armour technology. The Shir-2 project armour technology was called "PAGEANT", it was essentially the same thing, renamed, so the US didn't realise the UK was intending to sell BURLINGTON to Iran.


Sealordlawrence, - FV4211 used aluminium primarily to keep weight down to 55 tons, in order to reuse major Chieftain automotive components without impact on mobility (already marginal on Chieftain). For Shir, Iran wanted a new higher powered engine, which removed the weight restriction, and wanted steel, as they were concerned about stress corrosion cracking with aluminium armour.

On the 9 prototypes - see http://www.tanknutdave.com/component/content/article/305


Attached - Chieftain 5/2 BURLINGTON configuration.

 

[Abraham Gubler]

I was under the impression that Burlington was so-called for the US Army armour research base in the town of Burlington, Vermont... Chobham vs Burlington or backwards rationalisation gone mad?

 

[Przezdzieblo]

Form "Chobham armour" was used in official press release in 1976, but special armour programme was called that way much earlier. FVRDE guys called it also "Harvey`s armour". "Burlington" was a codename for programme at all, but there were also other designations of sub-programmes, f.e. of "anti-Burlington", of Anglo-German info exchange, of Anglo-Swiss deal about armour informations, of Americanized "Burlington". IMHO there is no problem with "Chobham armour" properness, it is just a matter of how deep people are involved with that story.

 

[overscan (PaulMM)]

No, the Ballistic Research Laboratory. See Hunnicutt's Abrams for instance. Interesting quote from there:

In early July 1973, Major General Robert J. Baer, the XM1 Project Manager, and personnel from the Ballistic Research Laboratory escorted representatives from Chrysler and General Motors to the United Kingdom for an update on the British developed Chobham special armor. During this trip they observed the proposed design of a new United Kingdom vehicle utilizing this special armor as well as the manufacturing processes required for its production. Based upon the newly obtained data, both contractors reevaluated their proposed armor configurations.

Chrysler made a number of changes, but they retained the basic design in their original proposal. However, General Motors made major changes in the configuration of their proposed tank. The most obvious change was in the turret where the vertical front and side walls were replaced by sloped armor. The modifications by both contractors
required additional work by the Ballistic Research Laboratory to develop new special armor combinations. By January 1974, both Chrysler and General Motors completed
the final design of their special armor configurations and some of the hull and turret armor structures had been delivered to Aberdeen Proving Ground for ballistic tests.

This was probably FV4211.


Here's GM's XM1 before and after the UK visit:


They do say imitation is the sincerest form of flattery

 

[JFC Fuller]

Overscan,


Iranian interest in the CV12 was not just down to power, the Leyland L60 was a horrendous engine and was notoriously unreliable. Using aluminium is not simply a way of making up for a poor power plant but also allows for weight to be distributed into other parts of the design- armour etc. MBT80 was to have made extensive use of aluminium and would have had a 1,500hp version of the CV12. I am not entirely sure when the CV12 project was started but it is unlikely to have been in any sort of advanced stage when FV4211 was being trialled.

 

[overscan (PaulMM)]

Overscan,

Iranian interest in the CV12 was not just down to power, the Leyland L60 was a horrendous engine and was notoriously unreliable.

Iran wanted a new engine, which, being higher powered, meant weight was not as much of an issue. I didn't say increased power was the only or primary reason.

Using aluminium is not simply a way of making up for a poor power plant but also allows for weight to be distributed into other parts of the design- armour etc.

This makes no sense at all. What you say above is "aluminium doesn't just save weight, it can also save weight".

In the context of FV4211, use of alumininium is explicitly mentioned as a weight control measure allowing uparmouring of Chieftain with the same basic engine without affecting mobility. Heavier armour = lower mobility unless you increase power. Therefore use of aluminium allowed fitting of improved Chobham type armour without increasing overall weight.

MBT80 was to have made extensive use of aluminium and would have had a 1,500hp version of the CV12. I am not entirely sure when the CV12 project was started but it is unlikely to have been in any sort of advanced stage when FV4211 was being trialled.

Don't understand what your point is here, unless you think I believe aluminium is only used on tanks with low power engines.

 

[JFC Fuller]

Overscan,

You seem to have interpreted an innocuous series of statements as an assault on your credibility- it most certainly was not. I was merely pointing out that the use of Aluminium in AFV design for weight reduction can be used to modify weight ratios between different parts of the design as well as to keep overall weight down and that the Leyland L60 was an awful engine (both true), whilst also musing as to whether continued FV4211 development may have resulted in the use of a different engine. That final point about engines is far from irrelevant as we know that in exactly the FV4211 timeframe FVRDE was encouraging RR to develop a rotary diesel engine based on the Wankel design- indeed FVRDE even funded RR to buy a license for the Wankel. This culminated in the 2-R6 at 350hp and a proposal for a 4 rotor version (4-R6) based on it rated at 700hp, possibly not coincidently the same as the original design ambition of the Leyland L60. The use of the RR CV12 family in design studies began in about 1972 when the rotary concept began to fall from favour before finally being abandoned in 1974.