Categories
Cold War British Prototypes Cold War Canadian Prototypes Cold War US MBT Prototypes

FV4201 Chieftain/90mm Gun Tank T95 Hybrid

United States of America/United Kingdom/Canada (1957-1959)
Main Battle Tank – None Built

ABC Countries

By the end of the 1950’s, tank development in both the UK and USA was becoming more streamlined with fewer outrageous ideas for atomic or super heavy monster tanks. The ‘Main Battle Tank’ concept had taken hold by 1957, inheriting the role of the medium tank. Heavy tanks were still seen, certainly in the US, as being the ones to take out the heaviest enemy armor but soon too that role was subsumed into the duties of the MBT.
The Soviets weren’t much for caring about such things and still had their own heavy tanks and well protected medium tanks which were causing consternation in the West. The Western powers lacked parity in both numbers and quality with the Soviets and both the US and UK had identified the need for a new medium tank for the 1960-1970 era. The United Kingdom, for instance, was still using the Centurion tank (a WW2 era design) and the USA, which was using the M48A2, was still developing the tank which would eventually become the M60.
In the short term, the UK would up-armor and up-gun their Centurions to meet the perceived threat of the Soviet T-55 tank until their own new tank, the FV4201, could enter production.
The FV4201 is better known as ‘The Chieftain’ and, despite being near the end of its development, many features still had not been settled on. The US equivalent program, the T95, was typical of US programs, an enormous entanglement of overlapping developments and was busily trying to encompass all of them. The project was still fairly new, however, with prototype hulls only authorised to be constructed in 1955. Thus, from 1957 to 1959, there were basically two tanks under development, the British Chieftain, which was nearing completion, and the American T95 which had only just started.
The United Kingdom, Canada, and the United States were already liaising closely in the new Cold War era on a variety of developments and tank design was not omitted from this. Work between the United States, the UK, and Canada, known as the ‘ABC’ countries (America, Britain, & Canada), had even achieved some degree of interchangeability and standardization for tank programs by 1957. Programs which had been fulfilled were standardization of the British 105mm gun, the British 120mm gun, an American version of the British 120mm gun, the American 105mm T254 and 120mm T123E6 guns, and three projects related to the FV4201 and T95.
These were:
-Mounting the FV4201 turret on the T95 chassis
-Fitting the US T208 90mm gun in the FV4201
-Mounting the US T95 turret on the FV4201 chassis
It was noted though that “in order to permit the FV 4201 turret to be mounted on the T95 hull, the U.K. consider modifying their turret ring with the T95 hull mounting surfaces”. It was agreed that “if the U.K. ring can be made interchangeable with the U.S. ring in respect to mounting surfaces on the hull, it will be possible to mount the complete turret providing major modifications are made to the turret basket”. The major modifications being that the British turret basket was too big for the T95, a smaller turret basket would be needed which would reduce significantly the amount of ammunition which could be carried. Even so, the expectation was that the T95 with a reworked 4201 turret and basket would carry at least 50 rounds of main gun ammunition. The panel reviewing the situation were adamant that all medium tanks must have ready rounds “stowed in the turret fighting compartment… in a favorable position for rapid loading of the main armament”.
That was not the end of the problems with the idea though. The turret bustle of the 4201 masked the air louvers on the T95 hull which “would undoubtedly affect the engine cooling”. One curious note records that one issue was that the driver’s periscope on the T95 hull interfered with the 4201’s gun mantlet. Exactly what this means is not clear as the FV4201 turret design was mantletless.

Guns

The British FV4201 was scheduled to enter production in 1962 with an expectation of prototypes available for trials by 1959. This new British tank meant to replace the Centurion was to mount a 120mm main gun using bagged charges. A lightened version this gun was also in development in the USA to weigh just 4156 lbs.(1885 kg). Since the initial specifications for the FV4201 were provided in the 1957 conference the design had changed slightly, improving the hull armor slope and the depression of the main gun (in a mantletless type turret) was improved from -7.5 degrees to -10 degrees.
The FV4201 turret would not be able to mount the T123E6 120mm American gun though as the weight would put the turret out of balance but it could mount the US 90mm instead. To do so would involve the use of an adaptor sleeve and the mounting surfaces of the gun but this was seen as having value for the tank in the short term.
On the other hand, the British 120mm bagged charge gun could be mounted in the T95E1 turret with only minor modifications made to the gun mount albeit at a weight increase of 1600lbs. (725.7kg). Of note here is that the T95E1 turret was the fifth turret in the American T95 program. When the T95 chassis was chosen to be common to both medium and heavy tank programs, five more chassis (for a total of 9) were ordered along with this turret. Four of those chassis went to the heavy gun tank program but as that program had no turrets ready three of the chassis were expediently fitted temporarily with existing turrets just for automotive trials. The remaining chassis got this new fifth turret and therefore was designated T95E1 to differentiate it from the others. The mention in the conference specifically for T95E1 can only, therefore, relate to this vehicle.

Medium tank guns

The 90mm T208 gun mentioned could fire the T320E60 APFSDS-T rounds at 5,200fps (1,585 mps) and defeat 5″ (127mm) of armor angled at 60 deg. at a range of 2000 yards (1828.8m). The other gun mentioned in the Tripartite Meeting on Tank Armament is the American 105mm T254 which is a lightened version of the British 105mm gun. The T254 was known to fit in the T95 turret, although “it is not planned now to install this gun in this type of turret since the installation is not ideal from the standpoint either of turret balance or turret configuration” but would be mounted on a T95 for test purposes (which would be known as T95E5). The advantage of the T254 gun was that if that gun became the standard US medium tank gun then it would be able to utilise the same ammunition as the up-gunned (105mm) British Centurion (assuming a suitable primer for the shell was selected). The Canadian contingent considered it “highly desirable that the gun and ammunition [for medium tanks] be standardized. To this end, the 90mm smooth bore can be placed in the FV4201 and the T95 turret modified to accommodate the 105mm X15 and possibly the UK 120mm bagged charge gun”.
The Canadians were anxious to see comparative firing trials between these two guns and to make an objective decision on their choice for a new medium gun tank although both were expected to exceed the requirement to defeat 120 mm of homogeneous armor plate at 60 deg. at 2000 yards which had been agreed as the standard at the Third Tripartite Conference.

Armor

Like the FV4201, the T95 was to use cast sections of armor for the nose with the sides and floor made from armor plate welded to the cast sections. This was a departure for the Americans who had already been using an all cast hull for the M48. The entire T95 turret was cast armor but the FV4201 turret was only cast in the front with the other sections made from plate armor welded on.
Overall, the T95 was expected to be a significant improvement over the M48A2’s which were already in service as “for example, the latter [M48A2] can be defeated from the direct front by the US 3000fps [914.4mps], 90-mm AP projectile on the upper hull front from 125 yards [114.3m] and on the turret front from within 1,550-yards [1,417.3m] range. The new medium gun tank, on the other hand, cannot be defeated from the front by this projectile”.
It was further theorized that the frontal armor was sufficient to defeat a theoretical Soviet 100mm AP shell traveling at 3,500 feet per second (1066.8mps) at 1,500 yards (1,371.6m) across a 60-degree arc. The armor was considered deficient, however, in terms of protection for the engine deck, sides, and rear, as well as having defective floor armor insufficient to protect from high-pressure mines. A final note on the protection for the T95 was the consideration of siliceous cored armor inside the frontal hull and turret castings although this still had not been done by this time and did not form part of the consideration for the interchangeability of the guns or turrets.

The Canadian Intervention

The Tripartite meetings of the ABC countries featured many Canadian needs. They did not class themselves as a tank producer nation, just a user, but they also had specific requirements they wanted from the tanks they were being expected to purchase. Being able to purchase either UK or US tanks effectively meant that the Canadians could be selective with what they wanted and expect that anyone who wanted to sell tanks to them would meet their demands.
For the new medium gun tank, they had agreed back in 1955 to the weight limit for this vehicle being set at 50 short (US) tons (45.36 tonnes). Both the T95 and FV4201 met this requirement, with the T95 being 20,000lbs (9,072 kg) under the weight limit.
The Canadians wanted standardization of guns, ammunition and gun mountings. They also demanded that any gun chosen had to meet the 120mm/60deg./2000 yard standard and be used in comparative firing trials. There is a small irony here that neither the FV4201 nor the T95 actually had that level of protection themselves. Further, the Canadians noted that, in comparing the designs of these tanks, the US had placed their emphasis on reducing the size of the vehicle and that while the T95 had less protection against kinetic energy ammunition than the FV4201, it did have a higher level of protection against chemical energy weapons (HEAT rounds).
In estimating the performance of the guns on offer, they determined that the UK 120mm bagged charge gun appeared to be more effective than the US 90mm smoothbore. In terms of sighting arrangements, the Canadians also preferred the British system for gun control as it was simpler, making use of a ranging machine gun compared to the US which “was still developing complex arrangements in preference to the ranging rifle system”.
In a nutshell, the Canadians wanted the best of both worlds, they wanted the hitting power of the British gun combined with the lighter, lower, more mobile US T95 to which they recorded that “the UK gun in the US tank would seem to be the logical answer. It may be technically possible to mount the 120mm bagged charge gun on the T95. With such a combination we should, for once, achieve a qualitative superiority over the Russians”.
The T95 with British gun combination favored by the Canadians was eventually effectively created by the US T95E6 mounting the 120mm T123E6 gun although the British 120mm X23E2 gun or lightened US version of it were still possible for mounting. In the meantime, while those experiments and considerations were going on, the UK had already submitted drawings to the Americans for a cost analysis for the re-engineering needed to fit the T208 and T208E9 guns in the FV4201. As it turned out, this project too came to nothing.
R.P. Hunnicutt (Abrams) records that the British 120mm gun was eventually mounted in a T96 turret in Study F of the T96 program (this being the heavy tank program) although the bagged charge was not popular with the US testers leading to the proposal to adopt a new breech and combustible case ammunition for it instead. The Americans were suitably impressed with the British 105 and 120mm guns though. So much so they made their own versions of them and “these two weapons and the original British guns were superior for tank use because of their lethality combined with lightweight, relatively short tubes, and short rounds requiring less loading space”. The only drawback of using the 120mm gun in the T95 turret was the necessity for a single loader to handle the two-piece ammunition” although a loader assist mechanism was considered to make this concern moot. Either way, the Americans elected to move on to a single piece round and modify the gun accordingly.
That modified gun was then fitted into a T95 turret in Study G (back to the medium tank program) producing a balanced gun capable of being stabilized for firing on the move.

T96 Study F turret with British 120mm bagged charge gun fitted on T95 hull. Note the use of a mantlet.Source: Abrams by Hunnicutt
T95 Study G fitted with the American version of the British 120mm gun Source: Abrams by Hunnicutt

Conclusion and one last hybrid

After the T95 program had been abandoned, the turret interchangeability concept didn’t go completely away. An initial assessment was even carried out on the XM60 as to whether it could take the British turret, the conclusion was that it was possible although it would certainly have been an odd-looking tank. The end outcome of all of the interchangeability studies is hard to gauge. The British stuck with their bagged charge gun, the American eventually chose their own gun for their own use and the Canadians were left without the tank they wanted. The option the Canadians had chosen suited their needs better than either the T95 or FV4201 could on their own: plenty of hitting power with a much more mobile vehicle. The T95 program was eventually terminated and the Canadians didn’t take Chieftains, preferring the mobility and firepower of the up-gunned Centurion instead.
The interchangeability of the guns was in itself a good idea, especially for replacement in wartime and the British turret and guns were well regarded. The interchangeability of the turrets was not easily rectified though, the Chieftain was nearly at the end of development and the British were unlikely to completely redesign the turret basket when there was no perceived market. The Canadians, after all, found the T95 turret acceptable in its own right, they just wanted the better gun. So, at the end of all this work, the overall outcome was that the interchange of T95 and FV4201 was indeed possible.
The FV4201 needed some work on the ring and basket, to take the T95 turret and the idea of mounting the T95 turret on the Chieftain was an altogether bigger task which no one was interested in trying. The report terminated discussion of the matter saying “it appears unlikely that the US T95 turret can be mounted on the UK FV4201 chassis without a major redesign of components which cannot be contemplated at this time”. As a result of the problems involved in modifying turret rings to match each other and overlapping demands for which gun was preferable, the whole affair was terminated with no prototypes completed.
The discussion does provide a real insight into just how hard it can be to design a tank to suit more than one role and customer and the idea of swapping turrets from the T95 and Chieftain tanks or even the XM60 as well as a variety of gun options remains popular if not in military circles then at least in those of modellers.

T95/FV4201 hybrid (T95 with FV4201 turret) specifications

Dimensions Length – 426.1 inches (10.82 m) (est. based on T95E6)
Width – 124 inches (3.15 m) (within the 124 inch limit imposed by the Berne International Loading Diagram)
Height – >112 inches (2.84 m)
Total weight, battle ready >32 US short tons est.
Crew 4
Propulsion air cooled, 8 cylinder, 560 horsepower AOI-119505A with 4 speed hydraulic converter-type transmission providing at least 13.5 horsepower per ton
Suspension
Speed (road) 35 km/h est.
Range >150 miles (241.4 km) at 17.5 mph (28.2 kph) with  230 US gallons (870.6 litres) fuel
Armament various options
Armor Sectional cast hull with welded plate and sectional cast turret with welded plate sides, roof and rear
Hull front upper – 3.8″ @ 65 deg. (96.5mm) (to be equivalent to 4.4″ @ 60 deg. (111.8mm)  which is an increase of 0.4″ (10.2mm) over the M48A2 which was 4″ at 60 deg. (101.6mm))
Hull front lower – 3.2″ to 5.5″ @ 50 deg. (81.28mm to 139.7mm)
Hull sides – 1.5″ to 4″ (38.1mm to 101.6mm)
Hull rear – 1″ at 0 to 20 deg. (25.4mm)
Hull top – 0.8 to 1″ (20.3mm to 25.4mm)
Hull floor – 0.5 to 0.7″ (12.7mm to 17.8mm)
Turret – FV4201
Total production zero
For information about abbreviations check the Lexical Index

T95E1 with British 120mm gun (the Canadian Option) specifications

Dimensions Length – 426.1 inches (10.82 m) (est. based on T95E6)
Width – 124 inches (3.15 m) (within the 124 inch limit imposed by the Berne International Loading Diagram)
Height – 112 inches (2.84 m)
Total weight, battle ready 32 US short tons est.
Crew 4
Propulsion air cooled, 8 cylinder, 560 horsepower AOI-119505A with 4 speed hydraulic converter-type transmission providing at least 13.5 horsepower per ton
Suspension
Speed (road) 35 km/h est.
Range >150 miles (241.4 km) at 17.5 mph (28.2 kph) with  230 US gallons (870.6 litres) fuel
Armament British 120mm bagged charge main gun with at least 50 rounds
Armor Sectional cast hull with welded plate sides, floor and rear, and fully cast turret
Hull front upper – 3.8″ @ 65 deg. (96.5mm) (to be equivalent to 4.4″ @ 60 deg. (111.8mm) which is an increase of 0.4″ (10.2mm) over the M48A2 which was 4″ at 60 deg. (101.6mm)
Hull front lower – 3.2″ to 5.5″ @ 50 deg. (81.28mm to 139.7mm)
Hull sides – 1.5″ to 4″ (38.1mm to 101.6mm)
Hull rear – 1″ at 0 to 20 deg. (25.4mm)
Hull top – 0.8 to 1″ (20.3mm to 25.4mm)
Hull floor – 0.5 to 0.7″ (12.7mm to 17.8mm)
Turret (T95E1) front – 7″ at 60 deg. (177.8mm)(compared to the M48A2 with just 3.7″ at 60 deg. (94mm))
Turret (T95E1) gun shield – 15″ (381mm)
Turret (T95E1) sides – 3″ @ 45 deg. (76.2mm)
Turret (T95E1) rear – 2″ (50.8mm)
Total production zero
For information about abbreviations check the Lexical Index

Links, Resources & Further Reading

Report of the Tripartite Technical Conference on Tank Armament – October 1957
Abrams – Hunnicutt
Fourth Tripartite Conference on Armour – October 1957
Tank Factory – William Suttie


T95 hull with XM60 Turret and standard 90mm Gun.


The hull of T95 Pilot No. 2 with 90mm Gun T208.


FV4201 hull with T96 Study F turret and British 120mm bagged-charge gun, without fume extractor.


T95 hull with an impression of an Americanised FV4201 Turret with M48/M60 style commanders cupola and 120mm gun with fume extractor.


T95 Hull with the standard FV4201 Chieftain turret and 120mm gun.

All illustrations are by Tank Encyclopedia’s own David Bocquelet.

Categories
Cold War British Prototypes

Chieftain Casement Test Rig (CTR) SPG

United Kingdom (1972)
Self-Propelled Gun – 1 Prototype Built

The Chieftain CTR ‘Jagdchieftain’

This prototype British Cold War self-propelled gun has received the popular nickname of the ‘Jagdchieftain’ because of its similarity to the WW2 German Jagdpanther anti-tank self-propelled gun (SPG). Its correct designation is the Chieftain Casement Test Rig (CTR). This is the name given to the vehicle by William Suttie in his book ‘Tank Factory.’ The Tank Museum, Bovington call it the ‘Concept Test Rig.’
It was a 1972 joint project between UK and the Bundeswehr (West German Army). In Germany, tank designers had been experimenting with the Panzer VT1-1 and VT1-2 Leopard 2 chassis SPG armed with twin 120 mm cannons. The Casement Test Rig (CTR) had a semi-fixed single gun. The gun was set in a casement hull superstructure on a Chieftain tank chassis. A lot of aluminum was used in an effort to reduce weight.
Jagdchieftain Concept Test Rig SPG prototype
This prototype test vehicle is often called the Jagdchieftain but its correct name is the Concept Test Rig (CTR) – Photo: Colin Rosenwould Tankfest 2011
In the early 1970s, NATO believed that to deal with an overwhelming force of Soviet armor the Allies would fall back while inflicting as many casualties as possible until more troops and tanks could be shipped into Europe from America and Britain. The designers wanted to create an anti-tank SPG that had a low profile, a powerful gun and that could travel just as easily in reverse as forward. It was to be the ideal ambush weapon that could wait for the enemy to appear in a concealed location then open fire inflicting as much damage as it could before quickly reversing out of danger to its next preplanned ambush location. For survival, the front armor would be thick and sloped.
This was not the first time a British casemated self-propelled gun had been proposed. There were the class 40, 50, 60 tanks as well as rival Vickers A,B,C,D designs and the Alvis external concept. None progressed further than wooden mockups.

The Engine

Underneath the superstructure is basically a conventional Chieftain chassis, In order to conform with British and German requirements it could be fitted with the British Leyland L60 engine or the Leopard tank ten cylinder MTU multi-fuel power pack preferred by the Federal German Army of that time. The chassis was slightly widened to accommodate the MTU power pack.
The exhaust system was slightly different to that on the operational Chieftain tank in that it had a raised box on top of the chassis
The exhaust system was slightly different to that on the operational Chieftain tank in that it had a raised box on top of the chassis. The rear stowage boxes are missing – Photo: Colin Rosenwould Tankfest 2011

The Armor

The front sloped glacis plate was to be heavily armored against all current and future anti-tank (AT) weapons in the 1980-90s. Had the ‘Jagdchieftain SPG’ entered production, it seems probable that the new Chobham armor would have been applied. This was not fitted to the prototype but was simulated by the addition of 5 tons of lead plate covered in sheet metal.
The prototype’s superstructure was fabricated from aluminum in order to try and keep the weight down but even so, the Mechanised Vehicle Experimental Establishment (MVEE) estimated the final weight would be 55 tons. The term ‘Chobham armor’ has become the common generic term for composite armor developed in the 1960’s at the British tank research center on Chobham Common, Surrey, England.
Front view of the Chieftain Casement Test Rig (CTR) SPG
Front view of the Chieftain Casement Test Rig (CTR) SPG’s sloped front armour plate prior to the gun being fitted
The Casement Test Rig SPG was based on the Chieftain tank FV4211 nicknamed the “Aluminium Chieftain”. After the project was canceled, the CTR was kept in storage to monitor the hull welds to gain information on deterioration of the aluminum armor.

The Gun and Crew

The main armament was intended to be the British 120 mm L11 rifled gun, although for trial purposes only a dummy tube was installed. Unlike the Swedish S-Tank, which had a fixed gun, the British CRT self-propelled gun concept allowed the gun to elevate from −10 to +20° and traverse +/− 2°, allowing fine tracking without moving the hull.
The crew of three comprised a commander and two driver/gunners. One of the drivers and the commander were able to drive the vehicle forward from their positions, while the second driver/gunner had a rear vision block to allow him to drive it backwards, so they could reverse away from the enemy after ambush without showing their rear. This enabled the vehicle to use the ‘Shoot and Scoot’ tactic.
Development of the Casement Test Rig SPG was inspired by Swedish S-tank that had the same driving configuration. Two of these Swedish vehicles had been tested at Bovington in 1968. During the development of the CRT a further ten S-Tanks were borrowed for a more intense assessment during a military Exercise called ‘Dawdle’ in Germany.

Trials

The Concept Test Rig was assembled by the Fighting Vehicle Research & Development Establishment (FVRDE) at Chertsey but trials at Woolwich confirmed what had been seen in Germany on Exercise Dawdle: accurate gun laying was inferior to a turret in terms of speed of engaging targets and that it could not fire accurately on the move. The project was dropped and the vehicle was eventually sent to the Tank Museum at Bovington in 1990.
Jagdchieftain Concept Test Rig SPG prototype
Chobham armor was not fitted to the prototype, but it was simulated by the addition of 5 tons of lead plate covered in sheet aluminium alloy – Photo – Colin Rosenwould Tankfest 2011

FV217 Conqueror self-propelled gun proposal

This design did not get past the wooden model stage. A prototype was not built mainly for the same reasons the Chieftain Casement Test Rig (CTR) SPG project was dropped. Some call it the JagdConqueror because of its resemblance to the German WW2 Jagdpanther but that was never its official name. It was called the Conqueror Casement Test Rig (CTR) Self-propelled gun (SPG). It was to be fitted with a 120 mm gun.
It seems a strange thing to do as the Conqueror tank was already armed with a 120 mm gun but this vehicle would have been simpler and cheaper to build (a factor that would appeal to politicians). It would also have had a lower profile and thus have been harder to target. It would have been an ambush weapon that would sit in wait for advancing Soviet tanks and fire at them from cover, when they came within range of its gun. It would not have been as adaptable as the tank version.
FV217 Conqueror self-propelled gun

CTR Specifications

Dimensions (L-W-H) 24’6″ (without gun) x 11’5″ x 9’5″
7.51 (without gun) x 3.5 x 2.89 m
Total weight, battle ready 55 tons (11000 Ibs)
Crew Commander and two drivers who also serviced the gun.
Propulsion British Leyland diesel L60, 695 bhp or
Leopard tank ten cylinder MTU multi-fuel power pack
Speed 48/30 km/h road/cross-country (29.82 mph/18.64 mph)
Range/consumption 500 km (310.68 miles)
Proposed Production Armament British 120 mm L11 rifled gun
Proposed Production Armor Chobham Armor
Total production 1 prototype

Sources

Ed Francis – The FV3805 Restoration Project
Chieftain by Rob Griffin
Colin Rosenwould
Tank Museum, Bovington, Dorset, England
Steve Osfield
Tank Factory, William Suttie, 2015

Gallery


Illustration of the Chieftain test rig by David Bocquelet
Jagdchieftain Concept Test Rig SPG prototype
Side skirts were used to protect the side of the vehicle. If it had entered production, Chobham Armour panels would have been attached on top of the skirt panels – Photo: Colin Rosenwould Tankfest 2011
Jagdchieftain Concept Test Rig SPG prototype
The gun and gun mantlet on the Concept Test Rig SPG were not real units – Photo: Colin Rosenwould Tankfest 2011
Jagdchieftain Concept Test Rig SPG prototype
The front stowage unit behind the head light on top of the track guard is missing on the CTR prototype – Photo: Colin Rosenwould Tankfest 2011
Jagdchieftain Concept Test Rig SPG prototype
The top mesh exhaust box was not used on the production models of the Chieftain tank – Photo: Colin Rosenwould Tankfest 2011
Jagdchieftain Concept Test Rig SPG prototype
The downward pointing exhaust pipe and rear stowage box are missing – Photo: Colin Rosenwould Tankfest 2011
Jagdchieftain Concept Test Rig SPG prototype
The rear skirt panel has been removed. You can see the support bracket – Photo: Colin Rosenwould Tankfest 2011
Handlebar steering system
The handlebar steering concept was used on the CTR. It was also tested on the FV432 Armoured Personnel Carrier (FV432 APC) – Photo: Ed Francis
Chieftain Casement Test Rig prototype without the gun fitted
Chieftain Casement Test Rig prototype without the gun fitted
Top view of the crew hatches and engine covers on the Chieftain CTR
Top view of the crew hatches and engine covers on the Chieftain CTR self-propelled gun

Categories
Cold War British Prototypes

FV3805

United Kingdom (1956)
Self-Propelled Gun – 2 Prototypes Built

The Design

The vehicle itself started back in the late 1950’s based upon the idea of using the hull of a Centurion tank and fitted with a BL 5.5 inch QF field gun (140mm howitzer) in a built up casemate on the hull. The idea was a good one offering commonality of automotive parts with the Centurion tank which was the main tank in service with the British Army at the time. A wooden mock-up of the vehicle had met with approval and two prototypes P1 and P2 were manufactured and underwent testing.
FV3805 Wooden mock up
This is the wooden mock-up of the Centurion FV3805 Artillery SPG prototype
The project eventually lost out by the early 1960’s to the FV433 self-propelled gun known commonly as the ‘Abbot’ and both prototype Centurion FV3805 SPG P1 and P2 were thought to have been sold for scrap. The Abbot was chosen because the FV3805 SPG was not air-portable and with NATO standardization of 105mm and 155mm guns the British 5.5 inch gun (140mm) was being made obsolete. With a limited traverse of the gun it was an inferior design to the smaller, lighter and more capable Abbot anyway.
The vehicle is built ‘backwards’ very similar to the WW2 Archer 17pdr SPG. The engine and gearbox are at the front and the superstructure built over the front of the machine but facing over the engine deck. The driver position was moved to the center of the vehicle on the left side.
wooden mock-up of the Centurion FV3805 Artillery SPG prototype in firing position
Wooden mock-up of the Centurion FV3805 Artillery SPG prototype in firing position
Following the unsuccessful trials P2 had its 5.5 inch gun and mounting removed and a steel plate with vision port welded over the hole in the front of the superstructure. Centurion FV3805 SPG P2 lived on in service as an Artillery Range Observation vehicle sporting the name ‘Major Picton’s Palace’ until sometime in the 1970’s when again it has vanished from military records. Research is still trying to locate the fate of P1 which is still lost. (Information – Andrew Hills)
Centurion FV3805 artillery self-propelled gun prototype
Centurion FV3805 artillery self-propelled gun prototype

The British BL 5.5 inch Artillery Gun

This artillery field gun was produced between 1941 to 1945. It weighed 13,647 lbs (6,190kg) and had a barrel length of 13ft 9in (4.19m). Its caliber was 5.5 inch (140mm). It fired a high explosive HE shell that weighed 100 lbs (45.5kg) and a smaller one that weighed 82 lbs (37kg). The 100 lbs shell could be fired at a maximum range of 9.2 miles (14.81 km). The lighter 82 lbs shell could be fired at a maximum range of 10.28 miles (16.55 km). The letters BL stand for ‘breach loading’.
FV3805 Centurion Artillery SPG gun crewFV3805 Centurion Artillery SPG gun crew
It was fitted with a Welin breech and Ashbury mechanism with a hydro-pneumatic recoil system. It had a rate of fire of two rounds per minute. The 100 lb shell was fired at a muzzle velocity of 1,675 feet per second (511 m/s) and the 82 lb shell was fired at 1,950 feet per second (590 m/s).
It fired two part ammunition. The high explosive HE shell was loaded first followed by the propellant charge canister that would have the correct amount of powder bags in it for the range of the target. It could also fire 100 lb smoke or colored flare marker shells. The normal HE fuze was No 117. In late 1944 a VT fuze T100 became available.
This gun was first used in the deserts of North Africa in 1941. Most British, Polish and Commonwealth forces were equipped with this gun. The normal organization was an artillery regiment of 16 guns organized into two batteries. It continued to be used during the cold war in conflicts like Korea. It was purchased by many different nations. Both Pakistan and India used this gun in their border wars. In the British Army it was replaced by the L121 FH-70 155mm towed Howitzer. It remained in UK service with Territorial Army regiments until 1980.
The 5.5 inch QF gun fitted inside the enclosed casement on the top of the Centurion tank chassis
The 5.5 inch QF gun fitted inside the enclosed casement on the top of the Centurion tank chassis

Ammunition

The following information was found in an original document covering the ammunition stowage on the FV3805 SPG.
(a) At least 25 HE rounds (fused) and 5 HESH (fuzed) are to be carried in the SP. It is desired to carry 35 HE and 5 HESH.
(b) Provision shall be made fro the stowage of:-
12 Bulk packed VT Fuzes
5 Cartridges charge 2 (7 if 35 rounds HE are stowed)
12 Cartridges charge 4 (17 if 35 rounds HE are stowed)
18 Cartridges charge super (27 if 35 rounds HE are stowed)
40 Tubes P.S.A
768 rounds .303 ball SAA
288 rounds .303 tracer

The 105mm gun

At one point in 1964, the Centurion FV3805 SPG was tested with a 105mm gun. The following reference was found on official records “16.2.64. Abbot mounting fitted to 5.5in SP (P2). Proofed at K Battery at 7½°. Recoil at 14 in – steady’”

MOD Shoeburyness

The following account is from Roger Walton who actually drove the Centurion FV3805 artillery SPG prototype whilst he was in the British Army: – In 1977 whilst serving in Northern Ireland I noticed a posting requiring a driver of tracked vehicles. I loved driving so I put my name down. In February 1978 I arrived at the Army MOD Shoeburyness and Foulness Defence Evaluation and Research Agency [DERA]* weapons testing complex, near Southend-on-Sea in Essex.
It was not a glamorous posting. I was in a team of 3 drivers, a Lancer from the 16/5th, one from 3rd Royal Tank Regiment RTR and myself being Queens Own Hussars, plus REME and 120 gunners.
It was my first time in a weapons proofing establishment and I was expecting to see loads of Chieftain tanks. My first Monday at the tank workshops I was horrified to learn that they only had one Chieftain, a rare mark one which was being used to calculate various things which the civilian boffins thought we didn’t need to know.
FV3805 being driven at the MOD Shoeburyness
The FV3805 being driven at the MOD Shoeburyness and Foulness Defence Evaluation and Research Agency weapons testing complex, near Southend-on-Sea in Essex
Back at the workshops, I was introduced to a number of AFV ‘funnies’ used for towing, recovery and as gun platforms. The Centurion FV3805 SPG was sat in yard. Never having seen this vehicle before I was keen to find out more so I asked after the beast.
It was explained that it was a prototype and had been intended for the artillery. At this time it was a none runner fitted with a 105mm gun from an Abbot Artillery SPG.
It was soon sanctioned by the powers that be to get it running so it could be used as an ammunition carrier whilst out on the sands firing range.
It did not take long to get her back in a running condition. I soon learned the quirkiness of this vehicle. The engine and gearbox were what I normally found in an old Centurion tank, except the drive was all reversed.
The gun was on a fixed/limited traverse facing over the engine decks. The driver sat to the left of the gun. The drivers control sticks, gear stick had all been shortened.
It didn’t drive any differently to a normal Centurion tank, but I do remember having a limited view to the front. I was totally blind due to the gun being on my right. You could see bugger all to the right. Also due to the higher than normal driving position obstacles had to be carefully negotiated. As a driver you had a small hatch which you had to be careful using due to the height from the ground.
The only obstacle on the base at this time was the sea wall. As you crested this we had to turn right to go onto the beach drive 100 yards or so to get onto the ramp onto the sands.
It was being used to carry and store ammunition for other vehicles being tested at the base. I remember one time it being used to take ammunition onto the beach to supply an American M110 that was being put through tests. After delivering the ammo the FV3805 withdrew back down the beach during the live firing of range safety rules.
*DERA is now known as QinetiQ (pronounced kinetic)

Artillery Observation Vehicle

At some point, the 5.5 inch gun was removed from the prototype FV3805 and the vehicle was converted into an artillery observation vehicle to be used on the firing ranges. The holes left by the removal of the gun were blanked off with armor plate and an observation glass panel was added instead. It was painted light blue instead of the traditional British Army olive green so it was noticeable on the firing range. It was eventually transported to Duxford when it was no longer needed where it stood out in the rain, sun and snow for a number of years.
FV3805 Centurion Artillery observation vehicle
The FV3805 Centurion (on the right) was painted light blue and used as an artillery observation vehicle after the 5.5 inch gun was removed. On the left is the FV207 Conqueror SPG prototype fitted with a 4.5 inch naval gun. Other guns were tried. The protective armoured casement has not been constructed yet.(MOD Shoeburyness beach firing range 5th June 1984.)

The Centurion FV3805 SPG P2 restoration project.

FV3805 P2 reappeared on the Isle of Wight, in Southern England at the Military Museum. Here she has sat outside in the salty air rusting away quietly and becoming rather sorry looking until 2015.
Phase 1 of the restoration; moving the vehicle under cover to dry out has been completed. The next steps will be to organize the stripping of the paint and components from the tank for restoration.
Phase 2 is getting the vehicle running. The biggest hurdle being the Rolls-Royce Meteor MkIVB engine which on inspection appears to be completely seized and likely is unrepairable. The gearbox is intact but needs an overhaul. The wheels and tracks are all complete.
Phase 3 is fitting the gun. The gun itself is problematic. There is a lack of 5.5 inch guns for sale at the moment.
The focus at the moment is on restoration of the running components so she can be shown to the public. The FV3805 Restoration Project is on Facebook at https://www.facebook.com/FV3805
(Information – Andrew Hills)
FV3805 awaiting restoration
FV3805 awaiting restoration on the Isle of Wight, England (Photos: The Mighty Jingles)

Ammunition stowage

At least 25 high explosive HE rounds (fused) and 5 HESH (fuzed) rounds are to be carried in the self-propelled gun. It is desired to carry 35 HE and 5 HESE.
Provision shall be made for the stowage of:-
12 Bulk packed VT fuzes
5 Cartridges charge 2 (7 if 35 rounds are stowed)
12 Cartridges charge 4 (17 if 35 rounds HE are stowed)
18 Cartridges charge super (27 if 35 rounds HE are stowed
40 Tubes P.S.A.
768 rounds .303 ball SAA
288 rounds .303 tracer.

Specifications

Dimensions (L-W-H) 7.82 m without gun x 3.39 m x 3 m
(25ft 7in x 11ft 1in x 9ft 9in)
Total weight, battle ready 50 tons
Crew 4 (commander, driver, gunner, loader).
Propulsion Rolls-Royce Meteor; 5-speed Merrit-Brown Z51R Mk. F gearbox 650 hp (480 kW), later BL 60, 695 bhp
Speed 48/30 km/h road/cross-country (29.82/18.64 mph)
Range/consumption 190 km (118 mi)
Armament British BL 5.5 inch Artillery Gun
Gun depression 3 degrees
Gun elevation 70 degrees
Gun traverse 30 degrees left and right from centre line
Rate of fire 3 rpm for 10min or 1 rpm for 3 hours.
Armor 35mm-195mm (17mm-58mm on cab)
Ammunition used 100 lb HE shell, 82 lb HE shell, 100 lb Smoke shell, 100 lb coloured flare shell.
Ammunition Stowage 76 shells and 96 charges
Total production 2 prototypes

Sources

Ed Francis – The FV3805 Restoration Project
The Wight Conflict and Remembrance Museum
The National Archives, Kew Memorandum TR 4/57, TR 1/58 Effect of 5.5 inch gun-muzzle blast on FV 3805
The Centurion and variants on Wikipedia
BL 5.5 inch Medium Gin on Wikipedia

Gallery

Centurion FV3805 artillery SPG
Wooden mock-up of the Centurion FV3805 artillery SPG. Notice the drivers escape hatch and vision slit to the left side of the 5.5 inch gun.
Centurion FV3805 artillery SPG prototype with limited travers turret built inside a fully covered casement.
Centurion FV3805 artillery SPG prototype with limited travers ‘turret’ built inside a fully covered casement.
Centurion FV3805 SPG with the 5.5 inch gun at full elevation
Centurion FV3805 SPG with the 5.5 inch gun at full elevation.
side view of the Centurion FV3805 SPG with the 5.5 inch gun
Side view of the Centurion FV3805 SPG with the 5.5 inch gun.
Centurion FV3805 SPG ammo storage racks on the right side of the vehicle
Centurion FV3805 SPG ammo storage racks on the right side of the vehicle.
Centurion FV3805 SPG ammo storage racks behind the drivers position
Centurion FV3805 SPG ammo storage racks behind the drivers position.
View of the rear hatch at the back of the Centurion FV3805 SPG
View of the rear hatch at the back of the Centurion FV3805 SPG with more ammo storage racks on both sides of the vehicle.
Centurion FV3805 artillery SPG in firing position
Centurion FV3805 artillery SPG in firing position at MOD Shoeburyness.
The only photo of the Centurion FV3802 SPG to show the top/rear hatch intact and open
A photo of the Centurion FV3805 SPG showing the top/rear hatch intact and open.
Centurion FV3805 SPG showing the top/rear hatch intact and open.
Centurion FV3805 SPG showing the top/rear hatch open.
Centurion FV3805 SPG showing the top/rear hatch closed
Centurion FV3805 SPG with the top/rear hatch closed.

Artillery observation vehicle

Artillery observation vehicle centurion FV3805
Artillery observation vehicle centurion FV3805 with the 5.5 inch gun removed. An observation window was inserted into armour plate to fil0e the gap left by the gun’s removal

Restoration project

This photo confirms that the last remaining FV3805 Centurion PG was the P2 prototype
This photo confirms that the last remaining FV3805 Centurion PG was the P2 prototype. It is not known what happened to the P1. P2 was nicknamed ‘Major Picton’s Palace’. For many years Major Ian Picton was in charge of ‘A’ Section Trials and normally involved with Sands Shoots at MOD Shoeburyness. It was warm inside and was a good place to lurk on a rainy day.
This photograph was taken of the Centurion FV3805 SPG at IWM Duxford before it was moved to the Isle of Wight
This photograph was taken of the Centurion FV3805 SPG at IWM Duxford before it was moved to the Isle of Wight. (Photo – Ossie)
Centurion FV3805 rear hatch
Because the Centurion FV3805 rear hatch is so large it is hoped that when the vehicle is restored to a running condition it will be the first AFV that can offer ‘tank rides’ to veterans and members of the public in wheelchairs.
The Centurion FV3805 SPG was originally painted British Army Green.
The Centurion FV3805 SPG was originally painted British Army Green.
Centurion FV3805 SPG P2 under restoration on the Isle of Wight.
Centurion FV3805 SPG P2 at The Wight Military and Heritage Museum 2015.

May 2019 Update

Tanks Encyclopedia writer Mark Nash visited the Wight Military and Heritage Museum in May 2019 to inspect the progress in the restoration of the Centurion FV3805 self-propelled gun P2. Unfortunatly there has not been any work undertaken on the vehicle for the past four years and, in the words of a staff member “has all but ground to a halt”. It is left out in the open without any covering and spider webs cover the hull. Its condition is deteriorating. This is very sad as it is the only surviving example of this vehicle. The owner has offered to sell it but the price he is asking is very expensive. (There is also an ownership dispute that has not yet been settled). The vehicle used to run but the engine has now seized due to water getting into the engine via the exhausts. Any useful engine parts have been cannibalised.

Looking in through the rear hatch, you can see the Drivers position in the front left corner of the superstructure. (Photograph: Mark Nash Photography)

This tattered piece of tarp weight down by a pallet and old tyre is the only protection the vehicle has from the elements. (Photograph: Mark Nash Photography)

A view of the cannibilised engine through the vehicle’s rear hatch. (Photograph: Mark Nash Photography)


Illustration of the FV3805 Centurion Self Propelled Gun (SPG) prototype by Jarosław Janas