From Crowoods Centurion
The FV3800 series
The 1947 policy on fighting vehicles (see Chapter 2. page 44) included a requirement for a number of Self-Propelled Guns (SPGs) These were unspecified at the time but investigations took place into the use of the Centurion hull as a base for both SPGs and support vehicles. The proposed requirements were:
FV3801 Gun Tractor
FV3802 25-pounder SP Artillery Field Equipment
FV3803 Command Post Vehicle
FV3804 Ammunition Vehicle
FV3805 5.5in SP Guns 1956
FV3806 7.2in SP Gun
FV3807 120mm SPAT Gun
FV3808 SP Mounting, Medium
FV3809 155mm SPAT Gun
The FV3805. The driver's hatch. located high on the superstructure to the right of the gun (as viewed in the picture) is open. His visibility seems to be limited but apparently it was deemed adequate. The forward-facing exhaust presented no problem.
A comedy of errors, or a compounded felony? The FV3802 with its 25-pounder gun is fitted with a Monowheel trailer. Note just five road wheels each side instead of the Centurion's six.
Of these, only the FV3805 and FV3802 SPGs reached the prototype stage. The FV3805 was unusual in that it was a reverse-drive vehicle. That is lo say that it was driven in the opposite direction to the gun tank, with the engine at the front. This demanded that the driver be relocated to a position to the left of the gun. The brakes and steering, operated by mechanical linkage in all other versions, were converted to hydraulic operation. Built by Leyland in 1957 from gun tank Mk7 03ZR07, the FV3805 carried a 5.5in howitzer. The first version, with a gun but no superstructure, was built to assess the feasibility of the reverse drive and the location of the exhaust. The second version was a much more complete vehicle with an integral superstructure. Besides the driver the FV3805 carried a commander, a gunner and a loader/radio operator. However the reverse drive, the key to the success of the design, was its Achilles' heel.
Of the two types, the FV3802 was arguably the more interesting vehicle as well as being less successful. Powered by the Meteor 4C engine with shaft-driven fans, it used a modified version of the Centurion's AEC-Rackham suspension, with two full sets of suspension units and a shortened set on each side, providing just five paired road wheels per side. Unlike the FV3805 it was a rear-engine vehicle. The gun was a 25-pounder field gun mounted with its barrel pointed to the rear, so to fire it had to be reversed, but as in the FV3805 the design exposed the softer engine compartment to enemy fire. All Centurion-based SPGs were abandoned in favour of the more compact FV433 105mm Abbott.
The Conway. Its 120mm gun and rudimentary turret look top heavy on the Centurion hull.
THE FV4004 CONWAY
The requirements outlined in the new policy of 1947 were gradually being refined in the light of requirements and cost. By late 1950. the FV201 was beginning to be regarded as somewhat superfluous, particularly as the Centurion was fulfilling the expectations of the tank regiments. However, the appearance of the first Soviet JS3 at the Berlin Victory Parade in 1945 had caused some interest. With the Cold War placing this tank, with its sloping glacis plate and huge 122mm gun. on the opposing side, that interest became great concern. Here was a tank that packed a big punch and was hard to hit. The main concern was to develop a tank that could knock out the JS3. That would take time although such a vehicle did eventually emerge: the Conqueror. However, something was needed in the interim period and the plan, in late 1950. was to mount a 120mm gun on a Centurion hull. The gun chosen was an American model, the L1A1 which was earmarked for the Conqueror. It would be mounted in a rolled steel turret made by the Auster Light Aircraft Company in Rearsby. Leicestershire, the same company that made the aircraft that were used by the Army's Air Observation Post Squadrons. The new tank would be the FV4004, code-named the Conway.
Development was not straightforward and by the beginning of 1951 problems were already presenting themselves. A wood mock-up produced in October 1951 clearly showed these problems. The gun had to be mounted high to allow for recoil without fouling the turret ring and this added to the weight, already limited to 50 tons, and to the overall dimensions and high centre of gravity which made transport by road and rail difficult. Nor did the turret design allow for an elevation of more than 10 degrees: hardly adequate for the long-range firing envisaged to knock out the JS3 without getting too close. Room was needed in order to store the large ammunition but the Centurion hull, designed originally for 17-pounder rounds, could only hold twenty rounds of 120mm APDS and HESH ammo.
Just one Conway was made, by ROF Barnbow, but by the end of 1952 the design had shown itself to be impractical. The development of the Conqueror was well under way. with the design already signed off in March 1952. The first Conqueror would come off the production line in January 1954 and was unlikely that the Conway would have any useful application with the Conqueror coming into service so soon after. In December 1952 the FV4004 Conway was cancelled. The sole example is preserved at the Tank Museum, Bovington.
FV4005 Stage 1, a single experimental vehicle designed solely to prove the stability of the Centurion or FV215 as a firm gun platform.
FV4005 Stage 2. The fabricated turret embodied two conventional recoil systems.
Along with a number of engineer and recovery vehicles, based on the FV200 hull, there would be types of Self-Propelled Guns (SPGs) as yet unspecified (see Chapters 2 and 6). With the Conqueror experiencing difficulties in production and the Conway abandoned, the much needed tank-destroyer role was unfulfilled and in their quest for bigger guns, the design engineers turned to the concept of the SPG. One train of thought, made apparent in November 1951. was that the only orthodox weapon capable of defeating without question 6in (150mm) of armour sloped at 60 degrees (LOS of 300mm) at a range of 2.000yd (1.830m) would be a 180mm gun. firing a squash-head round. The most likely mounting would be a limited traverse SP mounting with reasonably heavy frontal armour. Two versions of this equipment were considered:
1. A limited traverse lightly armoured SP mounting based on the Centurion hull for early production and weighing some 50 tons. This would be known as the FV4005.
2. A longer-term design based on parts of the FV214 and known as FV215.
FV4005 was to be designed in two stages. Stage 1 involved one experimental vehicle designed solely to prove the stability of the vehicle such as a Centurion or FV215 as a firm platform for a gun of this size. A traversing carriage embodied a concentric recoil system in a mounting in a trunnion on an undercarriage.
Stage 2 embodied two conventional recoil systems with a hydro-pneumatic recuperation and an independent run-out control. The undercarriage was similar to that of the Stage 1 design but of fabricated construction.
Weight considerations limited the degree of protection for the crew to no more than splinter protection. Progress was slow: by December 1952, the specification for the FV4005 had changed to a 183mm gun. and as late as July 1955 FV4005, a Stage 2 with the 183mm gun, was fitted with a hydro-pneumatic recoil system and a turret. But by August 1957 the vehicles were dispersed. The mounting on the Stage 1 vehicle was sent to Shoeburyness P&EE for its use and the hull returned to service. Another vehicle was sent to the Royal Military College of Science and others were kept at FVRDE.
Why had all this work been abandoned? The same reasons may be considered as those that caused the demise of the Conqueror, namely that the new 105mm gun under development for the Centurion was far more effective than the Conqueror's in that it could knock out the dreaded JS3. And this gun was fitted to a known, reliable base, the Centurion that was already in service. Common sense had. it seems, prevailed.