|A naked Conqueror turret|
That's where I came in, Although I do have a local Conqueror, I've not got a thickness gauge or any experience of using it, so the likelihood of me being successful is nil, but what I could do was start combing archives for a primary source answer. I did find some interesting stuff but no armour value. Again the mystery deepens. There isn't a given value. Even on documents that list all the other armour thickness, the frontal turret thickness isn't given, just the level of protection it is required to give.
But first, lets talk about the Conqueror's early life. In the late 40's the British opinion was that armour had the upper hand in the armour vs gun battle, and looking at Soviet tanks of the time they were concerned about tank armament. The British were facing a dilemma. On one hand they needed a weapon with a high enough rate of fire to "suppress" enemy positions during an attack, this of course was entirely suited to guns such as the 20 pounder or the US 90mm. But both those guns were deemed inadequate against the latest Soviet armour. The answer was obvious, looking back at the Second World War they could see a system that had worked, the Sherman Firefly and 75mm armed Sherman's that had made up a large chunk of the British armoured force.
So the plan was formed to give Centurion regiments a 120mm armed Centurion. Initial trials resulted in the FV4004 Conway, and it was foreseen that over time the tank could be developed into something with a lower turret.
As an aside, its curious to note that despite the perceived issues in 1948 the British were looking at developing a new infantry tank with utterly ridiculous armour (400mm-350mm) and only a 77mm gun.
The Conqueror was to be grouped into RAC regiments, with Cromwell's as command tanks, and armoured regiments would be equipped with Centurions with 20 pounders and FV4004 Conway's. However the Conqueror production and development went a lot faster than had been foreseen, and therefore the plan changed to one squadron in each RAC regiment and one troop in each armoured squadron would be converted into Conquerors. This resulted in a total requirement of 250 tanks needed.
|Note the direction the Commanders cupola is facing.|
But back to the armour values. The first big surprise was a 14mm Burster plate attached to the hull. This stand off armour was for the role of detonating HEAT and HESH warheads away from the hull. Some of you might ask why you've never heard of this before? Simply because it wasn't fitted in peacetime but was held as a theatre reserve to be deployed in the time of war. The other obvious question is how would that effect gun depression over the front hull? One suggestion was to shave 10mm of armour off the front slope to improve the depression, but that was never implemented. On the Conqueror although the gun could depress to -7.5 degrees, beyond -5.5 degrees a limiter kicked in that prevented the gun from being laid or used. This was in place because the Conqueror had a nasty habit of sticking its gun barrel into the ground. This was caused by the huge length of the L1 120mm barrel, which swung about a lot preventing it from firing on the move. See this video for an example, notice how much the gun barrel bounces around:
(video should start at 20 seconds in, if not that's where you want to be)
But what of the turret armour, the thing that set me off on the trip. Well the requirement was to be immune from the Soviet 100mm gun at point blank range through an arc of 60 degrees (30 degrees either side of the gun barrel). However after testing the best that could be achieved with the turret was that level of protection through half the required arc. This does allow us the ability to make a guess on the required thickness, as the documents helpfully included a table of Soviet gun performance.
But the issue remained that the turret wasn't very well armoured. That's when I hit gold. There was a proposal for a new better shaped turret, with drawing!
And to close off, here's some follow on data on the Conqueror, that's just to help you to form a picture of the technical abilities of a Conqueror.
Turret traverse speeds were measured and found to be between 22-24 seconds for 360 degrees. Maximum elevation of the gun was 15 degrees. Reloading the gun took seven seconds and the road speed was 21.3 mph.