Category: Cold War British Prototypes

United Kingdom (1960)
Main Battle Tank – None Built

Nicholas Peter Sorrell Straussler (1891* – 1966) is perhaps most famous for designing the inflatable floatation screen for tanks such as the M4 Sherman, commonly referred to as a ‘Duplex Drive’ or DD tanks.

Born in Hungary in 1891*, at a time when it was still Austria-Hungary, he had, as a young man, come to the United Kingdom in 1910 or 1911. He may have found work during World War One in one of the hundreds of ordnance factories supporting the war effort. Certainly, he was demonstrating his engineering skills when he filed his first patent in January 1911 for a rotary engine.

(*His UK death certificate indicates a date of birth which could be 1892)

Early Engineering Work

After the First World War, he remained in the UK and applied for British nationality, marrying Edith Arbib in 1923. His engineering skills quickly found purpose and, by 1928, he was running the firm of Folding Boats and Structures Ltd. He was also designing small scout cars both with and without armor, both for domestic use and for export. He was finally naturalized as a British citizen in February 1933.

He would eventually open a small workshop in Brentford, West London, and produced a variety of unusual-looking but highly effective designs in partnership with the Alvis motor company, which proved to be both effective off-road and ruggedly reliable, gaining him some limited production contracts. He continued with armored vehicle design work, operating as Straussler Mechanization Ltd. until it entered voluntary liquidation in 1941 and its assets sold off in 1942. He would marry a second time in 1944 to a woman twenty years his junior, Josephine Vassie, and produce one child, Roderick, in 1945. They divorced or separated in around 1958.

A complicated private life aside, his most famous contribution to the war effort was to build on his work on Folding Boats and create an erectable canvas screen and outboard motor, tested on a Tetrarch light tank in July 1940. By the spring of 1942, this unusual arrangement was accepted as part of the general solution to solve the problem of how to get tanks ashore for an amphibious assault. The Infantry Tank Mk.III, better known as the ‘Valentine’, was equipped with these screens as well. Later, by 1943, the Valentine was replaced as the primary vehicle for ‘Strausslerisation’ using a floatation screen by the Sherman.

That development was a successful addition to the Allied arsenal in WW2 and, clearly, Straussler was keen that this development see wider adoption.

Designing the Ultimate Tank

After World War Two, Straussler continued work as an engineer and was, at some point, inspired to try and design a new type of vehicle. This was to combine two of his areas of design expertise, a screen for helping vehicles cross water, and a highly flexible suspension system allowing for a wide range of movement from track units and wheels alike to improve mobility.

Key features of the main battle tank design were to reflect what he felt were the fundamentals that would be needed from an “ideal” tank, specifically:

• A vehicle as small and light as possible with a low profile.
• Screen around the tank to allow it to be amphibious in water.
• As small a crew as possible.
• The largest possible primary “heavy caliber” armament, which would be loaded, aimed and fired automatically.
• As much ammunition as could be carried.
• The ability to mount alternative or additional weapons as may be required or desired.
• Simple suspension system, allowing for ease of movement cross-country with low ground pressure and allowing the vehicle to operate on wheels or on tracks equally, including the braking system.
• Suspension units mounted or unmounted by means of the vehicle’s own power.
• Simple driving mechanism.
• Easy access.
• All-round visibility.
• A crew compartment distinct from the main gun and engine provided with its own ventilation.
• Easy maintenance with a simple and reliable design.
• Width of 3,150 mm.
• Railways loading width.
• Height “below that of a normal man” – 1,700 mm.
• 700 – 800 hp engine.
• 28 – 32 hp/ton. (28.4 – 32.5 hp/tonne)
• 2 speed gearbox.
• Wheel speeds of 80 km/h.
• 65 km/h on tracks.

“There is no Tank either projected or existing which has only a few of the features of the ‘Straussler’ let alone all the large numbers of highly desirable properties which are assembled in a single device. There is nothing in any of the design features which are mechanically, technically, or operational of doubtful or of difficult nature and which cannot be designed, and manufactured by any competent organisation to produce a highly successful tank”

Nicholas Straussler

Layout

The whole tank was to be divided into three basic compartments. The front compartment housing the crew, behind this was the ammunition compartment, and at the rear, the engine compartment and fuel.

The tank was to be of a very low profile, with the gun projecting directly out of the front of the well sloped glacis and with a flat roof to a slowly sloping back. On each side of the vehicle would be two pairs of track or drive units, consisting of four double rubber-tired road wheels on a common frame able to rotate around a central pivot and around which was a track. At the rear of the tank would be a large and permanently affixed electrically-driven and steerable propeller system to provide propulsion in the water for the tank when floating. To aid in crossing a water obstacle, the tank would also have a large fabric screen that could be installed and easily erected. When not in use, this was to be held in a “perimental trough” (a recess running around the outside of the tank) and sealed with a rubber gasket.

Each track unit was designed to be fitted with a pair of large cantilevered spring leaf units, providing cushioning on the move. Braking was to be provided within the unit as well, in the form of 8 large disc brakes, constituting a pair per track unit. Further, because of the electrical drive system, electrical braking could be employed as well, providing an easy and simple method to control the speed of the tank. The 600 mm wide track itself was not particularly important to Straussler, although he did suggest the use of a “spring leaf” type of track, as it was cheap and light and could resist the sort of sideways forces imparted on a track during turning using its flexibility.

The middle compartment, designed to house the ammunition, had within it a cage which was rigidly attached to the breech of the gun, which projected through the front of the tank, through the crew space, and into this section. Ammunition would be loaded through the roof via a large trap-door style hatch into the middle compartment. Likewise, in order to refuel or access the powerplant, another hatch was on top of the hull over the rear section as well.

Date

Sadly, there is no date on Straussler’s design for this low profile main battle tank. The design can, however, be roughly dated by some of the technology within it. For example, the ‘perimental trough’ mentioned by Straussler is similar in description and purpose to a patent design granted to Straussler in 1947. That design was for a collapsible screen, as before, for imparting buoyancy on an armored vehicle. However, this was to be fitted into an armored box around the vehicle to prevent damage, instead it would be a permanent ‘trough’ into which such a screen could go on a purpose-designed vehicle.

A second clue is the use of the folding propeller at the back of the tank. In March 1942, Straussler filed a patent in the United Kingdom for this design shown on a Valentine tank with a wading screen clearly in place. Although filed in 1942, this design was not granted a patent until 1945.

A further clue is found in the name itself ‘Main Battle Tank’. The term itself originated after WW2 and was first used around 1957. These three clues combined would imply a date of design of not earlier than around 1957 and perhaps as late as 1965 or so.

Armor

Armored side skirts could be fitted to enhance the protection of the vehicle and especially to protect the drive units. However, no other mention of armor is included in his letter accompanying the design and the drawing itself shows no implicit thickness of armor either. Based solely on the drawing, it can only be inferred that protection was to be very light and this would be in keeping with a planned weight of just 25 tonnes. Given the low weight, a relatively low level of protection could be expected and the vehicle would have to rely for its primary protection on its low profile. At just 1.7 m high, allowing it to be easily concealed or camouflaged, the armor, or lack of it, would leave the vehicle highly vulnerable to even just cannon fire.

Crew

Just two men were supposed to operate this vehicle according to Straussler’s design, specifically a commander and a driver. Access for them was by means of a large hinged “trap-door” arrangement on the roof of the tank, with one for each man. Each man would sit in the forward section of the hull, on the right, sitting upright alongside each other. This meant only their compartment would need forced ventilation.

As well as telling the driver where to go and operating the radio to receive their own instructions, share combat information etc., the commander was also tasked with firing the primary armament. Aiming and loading were done automatically as the primary sight (a telescopic periscope) for the gun was placed on the roof between the driver and commander’s positions. The sight could be shared so that, in theory, both men would be able to aim the main gun.

Armament

The ‘ideal’ characteristics for a main battle tank, as outlined by Straussler, had to include the largest possible primary armament which could be carried. For this vehicle, Straussler proposed a 120 mm gun, although he does not mention if it were to be rifled or smoothbore. Considering a probable design date of the mid to late 1950s and his British experience, this would strongly suggest a rifled gun as a logical assumption.

Straussler had proposed that guns should be loaded, aimed, and fired automatically and that the tank should carry as many rounds as possible. However, his design principles included the smallest possible size characteristics as well, and the result was that just 31 shells could be carried inside in the “shellcage”. With a predicted firing rate of up to 12 rounds per minute (one every 5 seconds), this meant a continuous barrage of fire of just 2 ½ minutes if firing took place without a break. The automatic loading system was to be driven by an independent electrical motor moving new shells into the breech and the casing from spent shells out of the breech. As the gun was fixed in a side-mounted gimbal, it could move in both traverse and elevation, both of which were controlled via a hydraulic motor by the commander.

Possibly, the most unusual part of the armament plan for the vehicle was the position of the main gun. The basic layout of the vehicle and the protrusion of the gun from the front implies a centrally ( or close to center) mounted gun, as this is commonly seen on numerous other vehicles of a roughly similar design, from the Jg.Pz. 38 t and Jagdpather, to the Swedish S-tank. However, this is not the case at all. Close examination of the drawings show that the gun was in fact offset to the front left, meaning that both of the crew were sequestered inside not only the front ½ of the vehicle, but also the front right of that third.

An advantage of this layout was that it obviated the problem of the mounting of the gun being too far back. As such, when the gun elevated, depressed or traversed, it would leave a large ‘track’ in the frontal armor which had to be empty to allow gun movement. Given the arrangements, this ‘hole’ in the front armor would not leave any weakness in protection for the crew, who would be separated by both a lateral and transverse bulkhead, meaning that all the barrel might need was some kind of flexible canvas shroud to prevent water ingress. The gun itself was rigidly fixed to the “shellcage” of 31 rounds and automatic loading mechanism. The drive motors were fixed at an angle, causing the shells to be carried at around 25º to 30º to the vertical in the center, directly behind the crew compartment. The drive motor was inside the right sponson. If the gun rotated or traversed, this angled arrangement would prevent fouling.

As well as the 120 mm main gun, 4 machine guns were also to be carried, of either a ‘heavy’ (i.e. 0.50 caliber) or ‘light’ (i.e. 0.303” or 7.62 mm caliber) type. These machine guns would be placed in a pair of turrets, with one on each side of the front of the tank’s hull, mounted on top of the mudguards over the tracks. These turrets would be rotated, aimed, and fired remotely from inside the tank, although this would seriously occupy the crew inside, who already had plenty to do. Nonetheless, the position of these twin machine gun turrets would, in theory, allow for a level of protection across a wide arc on both sides as well as to the front, although how these were to be aimed was not explained by Straussler.

Engine, Steering, and Propulsion

The vehicle was to make use of a hybrid-type of drive system, whereby an engine drove an electrical generator which, in turn, drove electric motors to drive the tracks and provide the vehicle’s propulsion.

Straussler wanted a multifuel engine, i.e. one which could run on petrol or diesel or any available fuels. This type of engine could be the ‘normal’ kind of piston-driven engine or the Wankel type of engine as an alternative system. The Wankel type engine consists of a single triangular piston with curved faces with reciprocates within a roughly ‘8’-shaped cylinder. They are commonly known as rotary engines and have seen commercial use in some sports cars but were, and still are problematic for some issues like lubrication. The advantages, however, offered by a Wankel engine would have appealed to Struassler, not only because of the larger proportional size to weight and power output characteristics, but also because this type of engine produced a more uniform torque than a ‘normal’ type of piston engine as well as less vibration.

Nonetheless, this desire or at least the consideration of a Wankel type motor harkened back to Strausssler’s work decades earlier and his 1911 patent for an engine of exactly that type.

This engine would drive a single generator which would then drive the electrical motors. One motor was provided for each track. With four tracks, that meant four motors. In his design submission, Straussler does not expressly detail the use of the motors, but this sort of system would have allowed the driver to vary the electrical current being supplied to each track in order to provide turning forces as well as providing redundancy from damage. For example, even if one track unit on each side was damaged by enemy fire and the motors stopped working, as long as there was at least one operational motor and drive unit on each side, then not only could the vehicle still move under its own power, but it could also turn. With a fixed gun, not being able to turn meant not being able to fight, so providing this kind of redundancy with 4 tracks was a rational and logical step. What it also meant was that the vehicle would be able to neutrally steer around the center of the four units by powering one side one way and the other side the opposite direction.

The system had other advantages in common with some other hybrid designs, namely in the layout of the vehicle. Lacking the need to have the engine and gearbox mechanically connected (as this system did not need a gearbox) to the final drives, it meant that it would create a more efficient internal volume unencumbered by rotating shafts and differentials, etc. Instead, the engine and generator could be simply connected by electrical cabling to the motors. Each motor would then drive one wheel within each track unit, so that, of the four double rubber-tired road wheels, the lead wheels on the front track units would be powered and so would the rearmost wheels on the rear track units.

Improved Mobility on Land and Water

The intention of Straussler was to have the tank as capable of moving on wheels as it was on tracks. This was not new, in the sense that the concept had been around for decades, most famously with wheel-cum-track machines, and the reason was exactly the same. Tracked vehicles tend to be better off-road, especially on a soft surface, as the tracks spread the load on the ground and gain more traction, whereas wheeled vehicles are better on hard surfaces, like roads. With less weight moving around, there was also less wear and tear.

In order to change between wheels and tracks, Straussler envisaged a hydraulic jacking system, whereby the center 2 pairs of rollers on each side could be lifted. By doing this, it would transfer the weight of the vehicle to be borne by the large driven rollers at opposite ends of each side. The tracks, once removed, could then be gathered up and stowed on the tank, as it would be driving on just the four driven rubber-tired road wheels.

When in the water, propulsion would be provided by both the tracks and by the electrically driven propeller at the back, which could be both steered as well as raised, so it did not foul with obstacles under the vehicle when not in use. When traveling in the water, the fabric screen would be erected from its collapsed position in the trough around the outside edge of the tank. The screen would neither make the tank taller than it had been beforehand, nor wider or longer. It would, in fact, only serve to displace enough water to provide the buoyancy the tank needed whilst floating in the water. The closest vehicle showing how this might have looked in real life if it had ever been made, is the Swedish S-tank.

Of note during the transit of the tank through water by this method is that Straussler envisaged that it could be used as a transporter too. Specifically, he stated that between 15 and 20 men could be accommodated on the roof, enough to form a small assault party to seize a structure or other without the need for boats.

This was not the only potential use for the roof space either. Quite why Struassler thought that adding a rocket launcher might add value to his design is unclear, although his inspiration perhaps might stem from something like the ‘Calliope’ system. He declined to outline what sort of rockets or other items might be mounted. It is possible, therefore, that he was thinking of this type of chassis for being the basis for vehicles like a bridge layer, but he declined to elaborate on the comment. Be it for rockets or men, the roof was available for transport, but hopefully not at the same time for safety reasons.

Suspension

The most complicated part of Struassler’s design was not the unusual gun mount, vehicle layout or even the roof-mounted screen and rockets. Instead, it was the suspension and this, perhaps more than anything else, is the primary defect of the design.

Nicholas Straussler was undoubtedly a talented engineer and had paid a lot of attention to vehicle suspension before WW2. In 1935, he filed a patent for a centrally pivoted system with separate sprung wheels as outriggers on each end and secondary sprung wheels underneath to provide tension and spread ground pressure.

The lineage of thought from this 1935 design to his MBT design is readily apparent with a close examination of the drawing provided. The same basic system was maintained, with a central pivot (dark blue) on a longitudinal frame (orange) and with a pair of large wheels (yellow) at each end of the beam. Around these wheels would go the track (green), but this design provided track tension and springing slightly differently. Instead of the coil springs as used in 1935, this design clearly made use of long leaf springs (light blue) linking the large wheels via their pivoting sub-frame (pink). With that long spring leaf above the central pivot, there was a single return roller (light orange) mounted centrally, directly above the pivot for the whole unit. Directly below this central pivot was another addition to his 1935 idea, and second tensioning wheel (light orange) and one which also served to provide track tension, as it was attached to another spring leaf (light blue) which was shorter than the top one but also attached to the sub frame for the main road wheels. In this way, whichever way the entire unit rotated during passage over the ground, this wheel would be pushed down against the track, providing tension and contact of the track with the ground. Likewise, when the hydraulic system was used to rotate the track units, it would be done to put one end of the unit in contact with the surface, presumably a road. With or without the track units fitted, this would serve to elevate the tank somewhat.

However, despite the seemingly advantageous nature of this suspension, Straussler chose not to patent it.

Conclusion

This vehicle was far from Straussler’s last design for anything, let alone military items. By the late 1950s, Straussler had retired from running a business but not from inventions. Living in Geneva, Switzerland, he continued to produce designs including a folding boat and a folding motorized tricycle, amongst other things. He returned to England and died in London in 1966, aged 75, leaving a long history of inventions and his folding screen floatation system as his defining legacy.

The Straussler MBT, however, was not one of them. The design was not going to get any interest from the authorities who, at the time, would have been building more conventionally designed vehicles, such as the Chieftain. The concepts in inherent amphibious capacity were useful ones, but not essential and the light armor and unusual suspension were perhaps just a step too far for the authorities to engage with. Likewise, the roof-mounted rockets were an unnecessary addition and added nothing to the fightability of the design and in fact detracted somewhat from the otherwise clever idea to have the roof plate serve as a means of transport for troops over a water obstacle.

Perhaps the cleverest part of the design is the hardest to see in the side view – the loading system. The British were not advocates at the time of automatic loading systems, let alone one mounted in the manner Straussler designed, but the ability to mount the gun in this way would have provided the vehicle with the ability to deliver substantial firepower quickly against an opponent, creating the effect of more than one conventional tank for less than half the crew.

It is hard to assess Straussler’s design as being perhaps a step too far as an invention and this perhaps is reflected in the lack of a patent submission for what was a novel layout and could quite rightly have received legal protections. Straussler was certainly no stranger to the process and maybe it is the fact that he did not specifically try and protect this layout that indicates that even he felt it had serious limitations too. The design today is in the files in the archive of The Tank Museum, Bovington, a mostly forgotten idea from one of the foremost engineering freethinkers of his generation.

Sources

British Patent GB1622, Rotary Internal Combustion Engine, filed 21st January 1911, granted 21st September 1911
British Patent GB453200, Improvements in or relating to wheel suspensions for endless track vehicles, field 4th March 1935, granted 4th September 1936
British Patent GB623427, Improvements in buoyancy imparting means for vehicles, filed 10th December 1946, granted 17th May 1949
England and Wales Marriage Registration Index, 1837-2005, Page 746, Volume 1A.
England and Wales Marriage Registration Index, 1837-2005, Page 801, Volume 1A.
England and Wales Death Registration Index 1837-2007, Page 268, Volume 17.
England and Wales Death Registration Index 1837-2007, Page 701, Volume 5C.
England and Wales Birth Registration Index, 1837-2008, Page 530, Volume 1A.
Fletcher, D. (2020). Strausslers and Alvis. https://www.keymilitary.com/article/strausslers-and-alvis

United Kingdom (1984-1986)
Main Battle Tank – 1 Built

Despite the progressive weakening of the Soviet Union in the 1980s, the prospect of a nuclear war in Western Europe was perhaps just as likely in that decade as anytime during the Cold War. The significant quantitative advantages that the Warsaw Pact had in tank terms had led to a serious rethinking in NATO as to how to increase the survivability and fightability of their own tanks. That redevelopment had been assisted in no small amount by the British development of a new type of armor called Chobham. This new generation of tanks had left some designs out in the cold and one of those was the Vickers Valiant or Vickers Mk.4. The Valiant failed to receive orders and was seriously damaged in a transportation accident. Its biggest problem, however, was considered to be the relatively low mobility, as the emphasis of the design had been on acceleration and torque rather than top speed.

With the design a failure and the need for a new successful product, the firm of Vickers was spurred at the end of the Valiant project to combine its own Universal Turret concept with a new high mobility hull and was considering its own options for a Valiant 2. When the hull for Valiant was ruined in an accident and with significant money already spent by Vickers and its partners, it needed a new option.

The solution to both a new hull and the mobility problem was found in the form of the West German Leopard 2 hull and mating the Vickers Universal Turret to that hull produced a very capable vehicle known as the Vickers Mk.7/2. The market being eyed was, once more, the lucrative Middle Eastern one.

The work on the Vickers Mk.7 built on the experience and knowledge of the engineers at the British firm of Vickers. That company, which had nearly a century of tank building experience was based in Newcastle-Upon-Tyne in the northeast of England. They had some export success with the Vickers Mk.3 and some failure in the form of the Mk.4 – better known as the Valiant. The success of the Valiant though was a Universal Turret concept. This turret could fit a variety of tanks through the use of a universal coupling, a design that also permitted the Vickers Shipbuilding 155 mm howitzer turret to fit a variety of vehicles. With the new Chobham-based armor package, this turret also offered a choice of guns that could be fitted, such as the RO L7 and L11 105 mm and 120 mm rifles and the Rheinmetall 120 mm smoothbore. The turret was a state of art design with modern optics, fire control, and armor, so adding this turret to the existing hull of the Leopard 2 provided a vehicle arguably better than the Leopard 2 or any other NATO tank then in service. From the Leopard 2 addition to the turret, the name was given as ‘Mk.7/2’.

Layout

The Vickers Mk.7/2 followed a conventional tank layout, with the driver in the front of the hull, the turret roughly centrally, and the engine in the back. The hull was identical to that of the Leopard 2. The turret was large and rectangular with vertical sides and an angled front made from flat panels. The gun, located centrally on the front of the turret, was flanked by a pair of smoke dischargers when it was on the Valiant. These would later be moved to the rear sides of the turret. On the roof were two circular hatches for the commander on the right, and the loader on the left. A rectangular sight was provided on the front right of the turret roof for the gunner who, in keeping with British general tank-layouts, was located on the right, in front of the commander. All 3 turret crew were positioned on a turntable that rotated with the turret and which was supported on steadying rollers as opposed to the conventional turret-basket concept. The floor of this rotating platform was covered with non-slip aluminum plating and also contained the ready-ammunition stowage.

The final crew member, the driver, was located in the hull on the front right, with an ammo rack to his left. The driver lay in a reclining position with automatic controls and steered by means of a wheel with a conventional accelerator and brake pedals.

Unveiling

Early ideas of using the upgraded Universal Turret from the Valiant project (repaired after the accident) had been looking for a new hull with improved mobility. Initially, Vickers had considered the existing Challenger 1 hull which would mean a joint Venture with Royal Ordnance Factory Leeds where it was made. At this time, however, ROF Leeds and Vickers were direct rivals competing for the same markets so this concept proved untenable. The German firm of Krauss-Maffei in Munich however, was much more receptive and, at the time, a hull with no weapons was not subjected to export controls meaning that, from the German point of view, that they could effectively be selling Leopard 2 hulls to countries where the government had export bans in place for a whole tank.

Work on the Mk.7 began in 1984 after trials of the Valiant elicited interest in the advanced turret with a goal to demonstrate the tank in the summer of 1985. The vehicle was unveiled on time in June 1985 and was set for Middle East demonstrations shortly thereafter.

Optics

A tank that is blind is worse than useless and modern optics are essential to the survivability and fightability of any vehicle. The optics for the Mk.7/2 were concentrated, as would be expected, in the turret.

The commander was provided with a slightly raised cupola consisting of 6 fixed x1 magnification non-reflecting Heliotype viewers. Sighting for the commander was provided by the French SFIM VA 580-10 2-axis gyro stabilized panoramic (360 degrees) sight. This sight had various magnification modes, x2, x3, and x10 and incorporated an nd-YAG-type laser rangefinder. In addition to this is a PPE Condor-type 2-axis gyro-stabilised image intensifier (Phillips UA 9090 thermal sight) displayed on a 625-line television monitor for both gunner and commander alike.

The gunner had a x10 magnification Vickers Instruments L31 telescopic laser sight with Barr and Stroud LF 11 nd-YAG-type laser rangefinder fitted with a projected reticle image (PRI) for ranging. In addition to this, he was provided with a Vickers Instruments GS10 periscopic sight for target acquisition. The loader was provided with a single AFV No.10 Mk.1 observation periscope.

Tracks and Suspension

The tracks and suspension for the Mk.7/2 were identical to those on the Leopard 2, as this was the hull on which the Vickers Universal Turret was placed. As such, suspension was provided by means of torsion bars for each of the 7 road wheels and 4 return rollers. Additional rotary shock absorbers were fitted to wheel stations 1, 2, 4, 6, and 7, and the 635 mm wide track was made by Diehl and fitted with removable rubber pads with rubber-bushed end connectors.

Automotive

The automotive elements of the Vickers Mk.7/2 were dependent on the engine and transmission of the Leopard 2 main battle tank. This meant that the power was provided by the German MTU MB873 Ka-501 12-cylinder 4-stroke turbocharged diesel engine delivering 1,500 bhp and a Renk HSWL 354/3 hydro-kinetic planetary gearbox containing all of the gear change and steering and providing 4 forward and two reverse gears. The top speed was 72 km/h. In the event of a failure of the automatic gear, the transmission could be used in manual mode with a single forward and reverse gear.

Armor

The Federal Republic of Germany (‘West Germany’) had received Chobham technology via the Americans after the British had shared it with them so it had come full circle to now have a German tank with the British Army and now a British turret to try and meet an export market in the Middle East. The hull armor was identical to that of the Leopard 2, with Chobham-type armor across the frontal arc on top of a rolled homogeneous steel armored base. The Valiant had saved a lot of weight using the unconventional approach of an all-welded-all-aluminum-alloy armor hull. Now, with the larger Leopard 2 hull in steel, the weight had gone up but, likewise had the engine power to move the vehicle

The turret was also a steel base structure and, although the exact makeup was never released, it should be borne in mind that the Valiant (or Mk.4, as it was originally) was based on the technology from the Mk.3. The Mk.3 had moved from an all-welded steel turret to a partially cast one to improve ballistic protection. Despite this switch, it appears that, in order to accommodate the blocky sections of Chobham, Vickers returned to an all-welded steel structure. This would be different to the Challenger 1 then coming into service – this had a complex steel half-casting covering part of the roof, sides, and all of the front to which rolled homogeneous armor was welded to complete the structure followed by the Chobham packs to complete the external appearance. Chobham armor covered the whole front of the turret and the sides to approximately ⅔ of the way back, at which point they became hollow boxes for storage around the rear corners. In the center of the turret at the back was the large and effective nuclear, biological, and chemical warfare air filtration system made by Westair Dynamics. Mounted externally, the unit was easy to access, making replacement and maintenance easier and consisted of a multi-stage high-efficiency filtration process and worked to create an overpressure inside the tank which served not only to keep gases out of the tank but also to evacuate fumes from the weapons.

An automatic fire fighting system, the Graviner Firewire CO2-based (could be switched for other gases, like Halon) was fitted to the Valiant, and an automatic fire fighting system from the Leopard was simply used on this Mk.7.

Firepower

The Universal Turret’s enormous selling point was not only the coupling allowing it to be mated to a wide variety of the most common tank hulls in the world’s armies at the time, but also the choice of different guns on offer. The Valiant had started with the reliable Royal Ordnance L7A3 105 mm rifled gun but this was quickly switched out for the L11A5 120 mm rifled gun. When it came to the Mk.7/2 tank, there was no option for the 105 mm gun as no potential buyer would have wanted one, as this was now the age of the 120 mm gun for NATO tanks. If the purchaser did not want the very capable L11A5 rifle, they could also choose the Rheinmetall 120 mm smoothbore which had been approved for the German Leopard 2 and the American M1A1 Abrams. With probably the most reliable hull in the world at the time (the Leopard 2), and this turret featuring some of the most advanced fire control of any vehicle, the addition of the best tank gun available in NATO and armor to match any contemporary, the Mk.7/2 was a true world-beater. Exports of this tank would technically and potentially mean that the UK was selling tanks as good as, or better than its own and those of its allies.

Ammunition storage for the 120 mm Rheinmetall smoothbore ammunition amounted to 44 rounds (20 in the hull front, 15 in the turret bustle, and 9 in the ready rack in the turret). With the British 120 mm L11A5 rifle storage was listed as being reduced to just 38 rounds. The reason for the low amount of stowage is unclear, as with this turret, the smaller Vickers Valiant was able to store 52 rounds and the turret was unchanged stowage-wise. Fifteen in the turret, plus an additional 20 in the hull rack next to the driver would make 35 meaning just 3 rounds in the ready rack instead of 9.

The elevation range for both of the guns was identical at -10 to +20 degrees. Loaded manually, the rate of fire was given as 10 rounds per minute (1 every 6 seconds). A Vickers muzzle reference system (MRS) on the end of the barrel added additional information into the computer system and the barrel was clad in a thermal sleeve to reduce distortion.

The fire control system and gun stabilization system was an all-electric system developed by Marconi. This system had a built-in laser rangefinder and a brand new ballistic computer to improve the chances of a first-round hit against static and moving targets as well as for supporting firing on the move. This system used the SFCS 600 computer derived from the GCE 620 system installed on the Vickers Mk.3 with some improvements known as the Marconi Radar Systems Centaur 1 system.

The RO L11A5 120 mm gun made by Royal Ordnance, Nottingham, was 7.34 m long and weighed 1,782 kg. It featured improvements over the earlier designs by using a forged upstand for the muzzle reference system and featured a smaller volume and lighter fume extractor than the L11A2. As a result of these changes, the gun was out of balance, so 7.7 kg of additional weights had to be added to counterbalance it normally.

Secondary armament included a single 7.62 mm Hughes chain machine gun mounted coaxially with the main gun and a second 7.62 mm machine gun (L37A2) in a remote-control mount next to the commander’s cupola on the roof. In total, 3,000 rounds for these could be carried. Both of these weapons were interchangeable with a variety of commercially available 12.7 mm machine guns.

Fitted with the British L11A5 rifled gun, firing trials were conducted in Egypt in 1985. In total, 43 rounds of Armor-Piercing Discarding Sabot (APDS) ammunition were fired at targets 2.6 m high between 1,100 m and 2,600 m, achieving a total of 32 hits – 74.4% accuracy. A second set of 40 shells (26 APDS and 14 Practice) were fired at the 2.6 m high stationary target between 1,100 m and 3,000 m, achieving 33 rounds on target – 82.5 % accuracy.

When the firing trials were repeated against a mix of stationary and moving targets using both gunner and commander’s stations to control the firing, a total of 65 APDS rounds were fired at ranges from 1,100 m to 2,370 m. In total, 37 rounds hit the target – 56.9 % accuracy.

A rate of fire of 6 rounds in just 43 seconds could be achieved using High Explosive Squash Head (HESH) ammunition (8.4 rounds per minute). In perhaps one of the most peculiar firing trials ever asked of a tank, the Egyptian team had the Mk.7/2 driven up an 18 deg ramp, brought to maximum elevation (20 deg.) and fired. The purpose was to test the strength of the coupling between the hull and the turret and firing an APDS shell to provide the stress. The British team expressed strong concerns about this test, not from the point of view of the coupling but because they really had no idea just how far an APDS round would go fired in this way even if the backdrop was the vast expanse of the Egyptian desert. Nonetheless, the round was fired, the coupling survived, and seemingly no random camel herd discovered the true range of a maximum elevation 120 mm APDS shell.

Markets

The market for the Mk.7/2 was a large one: Egypt. Egypt had been trying hard to modernize its military and, in particular, its outdated tank fleet. Mated to the Leopard 2 hull, the Mk.7/2 had been finished and formally unveiled in the summer of 1985 and evaluated for reliability and other parameters. Late on in that summer, the combined Vickers and British Army demonstration team led by Peregrine Solly and the Mk.7/2 were shipped out to Egypt for a very rigorous examination of everything including reliability, ease of maintenance, mobility, and firing.

The driving assessment showed it to have a range of 263 km cross country with an average speed of 55 km/h and a top speed of 80 km/h. On soft sand, just 151 km were driven, but it is noteworthy that the area selected was impassable by any Egyptian vehicles then in service. There, the Mk.7/2 managed to traverse the ground albeit at a reduced average speed of just 39.4 km/h. A further 274 km were then driven off-road, where it was still able to reach a top speed of 80 km/h and an average speed of 60.3 km/h.

Trials in the scorching 35° C Egyptian desert took place between 5th September and 1st October 1985 operated by both British and Egyptian crews. Firing trials showed the fire control system to be very good and that the MTU engine was easy to remove and maintain. Whether Egypt was ready to place an order is not known, but the Mk.7/2 had certainly made a good impression of itself. When the German government closed the chances of exporting the Leopard 2 hull, so ended the project and all chances of a contract with Egypt.

Termination

The tank had proven to be an effective combination of firepower and mobility. With the proven 120 mm British gun and the option to switch relatively easily to the German 120 mm gun if desired, and combined with the latest generation of optics, this tank was a fearsome opponent. With the Leopard hull, the tank gained a proven and reliable chassis and engine with the mobility found lacking on the Valiant but the project was just not going to happen. At the time, the export of an unarmed hull was not covered by German government export restrictions on arms, but by exploiting this loophole Krauss-Maffei could, in effect, circumvent the restriction to put a German-hulled tank into the hands of a nation which might other not be able to obtain the Leopard 2. It would also mean that countries that could buy the Leopard 2 could also buy this version which was better in many ways and also outside of the control of the German government. Virtually, at a stroke of a pen, the project was thus killed, the German government canceled the export of tank hulls, and lacking their own alternative, the Vickers Mk.7/2 was dead. A somewhat ignominious end to probably the best tank of the day.

Conclusion

The Valiant had not been a success and had died in ignominious circumstances only to be reborn as the Mk.7. The early plan to mate this excellent Universal Turret with the hull of the Challenger 1 to make the Mk.7 had failed due to competing business interests with ROF Leeds. Ironically, Vickers acquired ROF Leeds in 1986, when it won the contract for the Challenger Armored Repair and Recovery Vehicle. At the same time, Vickers had also taken over design authority from Royal Armament Research and Development (RARDE) at Chertsey. Yet this had come too late for the Mk.7 and, with the availability of the Leopard 2 hull, the chances for a second Mk.7 had appeared as the Mk.7/2. This was a world-leading design and yet, thanks to the German government pulling the plug on export licenses for the hull, this too failed. With no more options and no contracts for other vehicles, the attention for a market for the turret shifted from European and Middle Eastern eyes to South America. The technology of the Vickers Mark 7/2 turret seems to have been merged with that of the Vickers Mark 4 turret in order to create two brand new turrets for Brazil’s new MBT by Engesa, the Osório, which would also meet a similar ignoble end despite promising beginnings. The Mk.7/2 marks a true lost opportunity for a truly world-class vehicle.

Sources

Ground Defence International #69. November 1980
Ground Defence International #70. December 1980
Janes. (1985). Arms and Artillery. Janes Defence Group
Ogorkiewicz, R. (1983). Vickers Valiant. Armor Magazine March-April 1983
Lobitz, F. (2009). Kampfpanzer Leopard 2. Tankograd Publishing, Germany

United Kingdom (1958)
Self-Propelled Gun – None Built

Spartan began as a design study at the Royal Military College of Science, Shrivenham for a Weapon and Fighting Vehicle Design involving the Officers on the group as well as members of the Technical Staff Course. The project was for the design of a close support artillery weapon that would be able to take part in the 1958 Tactical Battle in Nuclear War doctrine.

The UK was both at the forefront and also, paradoxically, a late bloomer in the Self Propelled Artillery (SPG) game, with the first platforms being the Mk.I Gun Carriers in World War 1. These were built as a result of the tank making its debut on the battlefield and the sudden realization that conventional horse-drawn artillery could be left lagging behind a more mobile army. The first of these was ready on March 3rd, 1917, participating in a Tank Trials Day. Fifty vehicles were ordered by the Army, to be produced by Kitson & Co. While the thought process was in the right area, they were still hindered by their ungainly design and never used in anger.

Various other systems were experimented with and, running alongside, the UK also built a series of vehicles called Dragons (a name taken from the simplification of ‘Drag Gun’) but these were no more than mechanical mules. What was needed was an all in one system, which was solved by the Birch Gun.

The Birch Gun, named after General Sir Noel Birch, who was Master General of Ordnance at the time, was a coupling of an 18 pdr gun (83.3 mm) with a Vickers Medium Mk.II chassis by the Royal Arsenal. This produced what could be argued as the first modern SPG, with a front-mounted engine, rotating gun turret, a crew that could travel with the weapon, and good cross country performance. Birch Guns were used in the Experimental Mechanized Force maneuvers of 1928 but by 1931 they had all been removed from service. This revolutionary design, which put the army decades ahead of its rivals, went the same way as anything that was new, innovative, or remotely useful to the army; precisely nowhere, as they chose not to use it. This inability or unwillingness to adapt or welcome new concepts would stymie the British Army until the present day where they still have the same issue.

By 1939, the UK realized it was inevitably going to be embroiled in another war with Germany and her allies. Hitler’s rise to power and the swift annexation of Czechoslovakia followed by the invasion of Poland led the UK to try and rapidly get the next generation of military vehicles into service as it was clear that mechanized mobility had been key to Germany’s success so far. Unfortunately, lessons learned with the Birch gun were not replicated and throughout most of the Second World War, the UK’s mobile self-propelled guns were lacking compared to both her opponents and her Allies.

Post-war, the UK began to reinvest in the concept of mobile artillery and, with new threats looming in the shape of Soviet Russia, new doctrines and tactics had to be accounted for in the design work. Several different vehicles and concepts were initialized. The FV304 and FV305 were to be built on the FV300 chassis armed with 25 pdr (88 mm) and 5.5 inch (139.7 mm) guns. Work stopped with only partial construction on the first and early layout work completed on the latter.

FV3802 and FV3805 were another two programs. FV 3802 was to be armed with the 25 pdr. while FV3805 was to have the 5.5 inch gun. Both were mounted on modified Centurion chassis in rear large casemates. Two prototypes were made (P1 and P2), although neither were accepted for service.

Spartan

The introduction of tactical nuclear weapons (one must remember that, at this point in history, the consensus all round was that the next war would be nuclear without a doubt) left the army in need of new tactics based around mobility, counter-attack, and survival in an irradiated wasteland that would be the conflict zone. To avoid offering a nuclear strike target, the artillery had to be able to concentrate its effort by increased range, rate of fire, and lethality whilst having good mobility to remain dispersed and yet stay in contact. Protection also had to be altered. Open topped vehicles were unsuitable for this type of warfare and therefore protection had to be ensured to protect from flash burns, secondary blast effects as well as conventional threats.

The designers decided that heavy and conventional artillery would be required to break through the surviving enemy defenses, larger long-range field guns would be situated further back from where it’s believed tactical nuclear weapons would be used, and so they settled on the mobile medium range of SPG. Each vehicle would need to be amphibious without preparation (to prevent crew being irradiated), highly mobile with long endurance, and carry enough supplies to allow logistics trains to be reformed behind them.

Spartan was to be built of relatively thin welded steel armor stiffened with support braces with priority given to extra room for supplies and the large volume of ammunition that was expected. This increased internal volume also helped with buoyancy. In order to get the high arc of fire required to effectively ‘lob’ shells over ridgelines and areas in which enemy forces may be hiding, the gun was positioned as high above the vehicle floor as possible to allow for a lower breech drop. To achieve this, the gun cradle was to be suspended from two beams arched across the roof.

The fighting compartment housed a five-man detachment consisting of the commander, two loaders, gunner and driver, and 210 rounds of ammunition. Charges, fuses, and other requirements were kept in sponsons to either side. Large rear watertight doors to the back could be opened to assist in loading shells, which were gravity fed to assist the loader in battle. Other than being airtight with an overpressure system to prevent gas biological and nuclear agents from entering the vehicle, the armor itself* would stop harmful gamma rays while a plastic spall liner would protect against fast neutrons. All the optical devices had polarizing filters to prevent blindness from nuclear flash.

*While the original authors quote the armor would be adequate, correspondence between the author and a nuclear physicist confirmed suspicions that such material would offer no protection against the level of gamma radiation likely to be received.

Automotive power was provided by a turbo-blown, supercharged 400bhp Foden FD12 compression ignition engine which could run on fuels ranging from Diesel, Avtur, Kerosene, and MT 80. Sufficient fuel was carried to allow for a 24-hour operational day and the power and speed allowed it to keep up with other MBTs at an average combat speed of 15 mph (24 km/h). A Merritt Brown gearbox and disc brakes were fitted for the final transmission. The entire powerpack could be extracted via the rear doors on a pull-out roller sheet due to the gun and seat etc. being mounted from the ceiling.

The suspension was via 12 road wheels in 6 pairs on either side via hydraulically adjusted torsion bars allowing the vehicle to lower itself to the ground to provide a stable firing platform.

Firepower

The gun was designed to replace the 25 pounder field gun and the 4.2 inch mortar in service. At a high angle, it was to engage targets between 1500 yards and 17,500 yards (1.4 km to 16 km) with a rate of fire of eight rounds a minute and new ammunition giving a marked performance upgrade over the 25 Pdr. The gun itself was a twelve-foot long (3.6 meter) monobloc non-autofrettaged barrel.

Autofrettage is a process by which the barrel is produced from a smaller caliber one by increasing the pressure on the inside of the barrel past its elastic limit. This enlarges the inner diameter of the barrel by pushing the inner layers of the barrel outwards, thus increasing the density as well. This gives a higher density barrel with better strength, lifetime, and safety. Made from a single forging of high-quality steel with a yield of 55 tons per square inch the gun was fitted with a fume extractor to assist with drawing fumes from the main compartment.

The gun was built to handle UK 105 mm HE and HESH bagged charges. However, an adaption existed to fit a replaceable liner and breach block that would allow it to use the US 155 mm rounds if required, this procedure taking about 2 hours. The new HE round was torpex based with a 60/30/10 mic fo RDX/TNT/AL mixture and an explosive filler of 6.6 lbs (3 kg) offering 250% more effective explosive volume over the older 25 pdr round. The horizontal sliding breech block was fitted with a semi-automatic gear for opening and closing the breach.

An automatic tube loading device with a tube magazine was incorporated for use when the British ammunition was fired. The ring-type cradle had parallel extension members at the rear to take anti-rotational slides for the block. The gun rammer was provided by compressed air in the engine compartment.

Sighting arrangements for the gun consisted of a conventional rocking bar sight and a long-necked dial sight. Laying for elevation was by means of a quadrant elevation bubble clinometer. A separate anti-tank periscope sight was mounted outside the cupola roof to avoid the effects of heat shimmer on the barrel.

Conclusion

The Spartan project certainly identified an area of light Self Propelled Artillery that was required for the MOD and the factors identified were already being used in several Russian developments despite there being no common communication between the developers. To add credence to this, a few years later, the F.V.433 Abbot began development which is remarkably similar in many ways to Spartan and may well have taken inspiration from the preceding project.

Sources

SPARTAN: Royal Military College of Science.
Discussions with Lucian Stan regarding radiation penetration

United Kingdom (1977-1984)
Half-track – ~9 Built

Land Rover, as a brand, has achieved somewhat of a cult status since the firm first unveiled the ‘Series 1’ vehicle at the Amsterdam Motor Show in April 1948. The mindset behind the vehicle, right from the start under the control of Maurice Wilks, was to produce a vehicle based on the idea of a WW2 era American Jeep but with its mechanical problems resolved and capable of operating in the civilian world as a utility vehicle and tractor. The Land Rover or ‘Landy’, as it is affectionately known, proved in the years since 1948 to be a simple, reliable, and rugged vehicle. Affordable and relatively easy to maintain, the body, made of duralumin, was rust resistant, meaning these vehicles endured for decades. By the end of 1976, over 1 million vehicles across various marks had been built at the Solihull plant in Birmingham. This rugged, simple reliable vehicle had an established market with several armies, not least of which was the British Army.

At the end of 1977, the Anglesey-based firm of Laird sought to reshape the well-proven Land Rover in a new form to provide a more capable off-road platform for military use, capable of a variety of duties and with a higher load capacity than the Land Rover. Work would end in 1984, when markets for the vehicle dried up, leaving the Centaur one of just a few half-tracks of the modern era.

The Name

The Centaur of Greek Myth was the offspring of Centaurus, with many myths about them on their savagery, bawdiness, and even wisdom on occasions. In common parlance a Centaur, half man half horse, is simply seen as the amalgam of human knowledge with the speed and power of the horse. In this regard, the Laird Centaur was well named, combining the mature driving ‘human’ Land Rover half with the tracked back end from the CVRT.

Unveiling and Markets

With a strong history and a rugged proven platform behind the Land Rover, as well as potentially lucrative markets at home and abroad, the firm of Laird started work in November 1977 on making a cost-effective tracked off-road platform which would be capable of fulfilling various types of roles. This would be based around the front half of a Land Rover married to a lengthened high strength load platform carried on a modified shortened form of suspension taken from an Alvis Scorpion CVRT. Concept approval was gained in December 1977 and an engineering model was begun in January 1978. Completed in April 1978, it appeared at the British Army Equipment Exhibition in June 1978.

Following this concept, there was a period of modification which ran through September 1978 until a pre-production prototype was approved that month. Production of the first vehicle began the following month.

The Land Rover had been widely exported, as had the Scorpion, which meant there was a relatively small logistical footprint for operating and maintaining the Centaur. The first vehicle was finished at Laird’s works in Anglesey in April 1978 and began trials in May to show off its capabilities.

Testing of the first vehicle was finished by the Motor Insurers Research Association (MIRA) in April 1979, after having traveled 3,687 miles (5,934 km). This was followed by 3 months of cold-weather testing which took place in Norway, followed by tropical trials in Libya and Tunisia. The second prototype, P2, was sent on a sales tour of Nigeria from July to August 1979 and P4 was sent to Oman that August as well. P5 was allocated to the British MOD, and P6 was to be sent to Kuwait and the United Arab Emirates.

https://www.huntleyarchives.com/preview.asp?image=1017722&itemw=4&itemf=0001&itemstep=1&itemx=1
Laird Centaur 06SP17 filmed during trials in Norway.

In total, the vehicle was 5.62 m long and just 2 meters wide, meaning it would fit into a variety of cargo aircraft fairly easily. The internal space in the back, behind the cabin, had a well in the center, between the sponsons that were over the tracks, measuring 1.05 m wide x 2.6 m long. Above this was the full cargo space measuring 1.78 m wide x 3.28 m long. Height varied by model.

Six pre-series vehicles were built and prepared in various configurations for testing. One was retained by Laird for their own use and promotion, another by Rover (owners of the Land Rover brand at the time), another (P3) went to Racal Tacticom for fitting out with electronics and radios, and the remaining four were sent for evaluation.

Variants

Three specific variants were proposed for feasibility studies by the British Ministry of Defence (MOD), although it is not entirely clear what those three were. Based on the trials, they would appear to be a rigid-body version as an ambulance/command post, a general duty soft top vehicle, and a hard-top armored personnel carrier. There were several other versions proposed, however:

Prime Mover/General Purpose – the ‘base’ vehicle, whether fitter for radio or not, with just a soft-top /canvas tilt for general haulage duties.

Fuel/Ammunition Resupply – a general-purpose vehicle carrying a 2,700-liter liquid bladder in the back.

Mine Layer – both as a carrier for the 72-tube Ranger EMI anti-personnel mine and for towing the British bar minelayer. It was able to scatter hundreds of anti-personnel bombs and lay up to 700 anti-tank bar mines in under an hour.

Command Post – rigid body with a pair of windows on each side with multiple radios fitted along with a map table.

Stretcher Carrier/Ambulance– with space for up to four full-length stretchers, the rigid body ambulance variants could go where other ambulances could not so as to retrieve wounded men and return them to the aid post. This is basically the same body as the command post variant but without the radios.

Tank Destroyer – drawn as fitted with a 120 mm Wombat anti-tank recoilless rifle mounted in the back.

Armored//Unarmored Personnel Carrier – the platform had a load capacity to enable it to be converted with a light ballistic body to serve as an armored personnel carrier. Even without this extra protection, the 5 mm hull floor protection and tracks enabled the Centaur to move up to 10 men across an area strewn with anti-personnel mines in relative safety. An enclosed canvas tilt would be able to keep the weather off and this was standard across all of the open-top variants. The fold-down tailgate acted as convenient access to and from the rear of the body just 0.43 m from the ground with simple bench seating along the sponsons above the tracks.

Reconnaissance – open-top with the upperparts and door removed, the Centaur reconnaissance version provided a mobile platform for scouting and was proposed with a pair of 7.62 mm General Purpose Machine Guns (GPMG).

Missile Carrier – a missile carrier version was displayed at the Paris Air Show in 1979 fitted with missile mountings for either the French HOT or European MILAN anti-tank guided missile systems. Even as just a haulage vehicle, there was sufficient space for two such launchers, crews, and space for 27 missiles.

Air Defence – one option for the Centaur was to use its rugged platform as a dual purpose fire support and air defense version. Fixing a gun-shield-equipped S20 pintle mount to the rear deck, the otherwise unarmed and unarmored Centaur could provide highly mobile air defense. With the 20 mm Rheinmetall Mk.20 Rh 202 cannon, it was capable of providing protection for convoys or troops against targets up to 2,000 m and was capable of 1,000 rounds per minute. A second version was also trialed, mounting the Oerlikon GAM-BO 20 mm cannon instead.

Laird Centaur 06SP17 with Bar Minelayer. Source: Laird

Laird Centaur 48BT07 fitted with the 72-tube EMI Ranger anti-personnel mine launcher during testing. Source: IDR and Empire’s Twilight

Hard-top body painted up as an ambulance and an artist’s impression of a pair of them in use. Source: Laird

Unarmored and unarmed personnel carrier along with armored body version fitted with a single 7.62 mm GPMG on the roof. This light ballistic body could be used for moving troops with limited protection from enemy small arms or shell fire or as a box-body for other purposes. Source: IDR

Reconnaissance variant as proposed in artwork from Laird and fitted with a pair of 7.62 mm GPMGs and pictured with troops from Oman. Source: Laird

Automotive

The structure of the automotive elements was as simple as could be managed. With the tracked part at the back based around elements taken from the Alvis Scorpion CVRT, no bespoke wheels, tracks, suspension springs, engine, transmission or other elements were used. The front part was just a Land Rover cab and controls with the same front wheels, steering rack and semi-elliptical leaf-springs with double-acting hydraulic telescopic dampers. One interesting note on the front wheels is that these were also offered with the Tyron run-flat safety bands, so even a puncture from the terrain or enemy fire would not cripple the drive. The tires ran on a track center of 1.33 m, whilst the tracks ran at 1.63 m, meaning that the rear footprint of the vehicle was slightly wider than the front.

The 5 double road wheels ran on Scorpion-type track but the wheels were smaller than those on the Scorpion. These track units were also shorter, putting down 1.06 meters of track on the ground at each side. The whole vehicle was powered by the 115 kW Rover 3.5 liter V8 petrol producing 1260 Nm of torque at 2,500 rpm. The engine was connected to the standard manual synchromesh gearbox from the Land Rover with 4 forward 1 reverse gears as well as the standard high/low ratio box allowing for all of those gears to operate in high or low range to create 8 forward and 2 reverse gears.

Not only are the front wheels driven like a ‘normal’ Land Rover operating in 4-wheel drive mode but the rear-drive, which would normally go to the rear wheels, instead went to Scorpion final drives to turn the sprockets. On either side of the ‘rear’ differential (at the front of the track units), there was also a pair of twin-caliper disc brakes to assist in steering. The ground clearance was 0.25 m. Of the 6 vehicles produced as prototypes P1, P2, and P3 were made in right-hand drive, and P4, P5, and P6 were built in left-hand drive. At some point after purchase in Oman, P4 was refitted with a Chevrolet 5.7 liter V8 petrol engine and an automatic gearbox – no details of the performance are available.

The share of drive to front and rear respectively was regulated through a differential built into the gearbox, providing equal power to both of which could be locked to improve traction over soft ground. The tracks, suspension at the back and drives were all interchangeable with the British Scorpion. The rubber-padded tracks made for a quiet and durable track for running both on and off-road. Suspension for the track section was provided by means of a torsion bar and tensioning by means of a hydraulic adjuster.

Enough fuel was carried in a single 200-liter petrol tank for up to 700 km of road use, although this would be reduced with a load it would carry or off-road, uphill etcetera. The fuel tanks in the Land Rover were normally held under the seats in the cabin in simple tanks, but here the tanks were made from ‘Explosafe’ to protect the tank from rupture. Fuel consumption was fierce and, during testing, the Centaur was found to use 4.15 mpg (1.47 liters per km).

To make it useful as a prime mover or other variants, the Centaur was provided as standard with a NATO compliant British tow hook. With this it could tow any of the standard NATO duty trailers or other equipment like a light 105 mm gun, fuel bowser, or even the Bar Mine Layer.

Armor

In general, the Centaur was unarmored, although there were some ballistic kits for the body on top of the normal ballistic kits already in widespread use, like the fiberglass and plastic-based vehicle protection kit (VPK) in use for internal security in Northern Ireland at the time. As a standard feature, however, a 5 mm thick steel plate was fitted underneath the whole vehicle as protection from mines.

Vehicles

The six vehicles produced by Laird, known as P1 to P6 which were extensively trialed. P1 was trialed in Libya and Tunisia. P2 was sent to Kenya and Nigeria for trials before being returned to the UK. P3 was modified for trials with a hardtop body fitted with radios for use as a mobile command post, whereas P4 was sent for testing in the deserts of Oman where it was purchased by the Sultan. P5 was fitted with the mine-launching rocket system and later fitted with a 20 mm cannon. P5 survives in the Bovington Collection. P6 was sent to Iraq in 1979 or 1980 for trials before being returned to the UK but was sold back to Iraq in 1980. Found in a scrapyard in Kuwait in 2005, the vehicle was recovered and is currently in private hands for restoration. Another vehicle based on the Land Rover Defender 110 (long wheelbase) was designated P7 and an eighth vehicle designated P8 remains incomplete at The Tank Museum Bovington.

Conclusion

The Centaur, for all of its potential and capabilities, was seriously expensive for what was really just a slightly better off-road 3.5-tonne truck. When it was shown off in 1978, the cost was GB£35,000, the equivalent of just over GB£175k in 2020 values (US$215k), and this seems to have dissuaded potential buyers from this otherwise interesting vehicle. There were no doubt other problems for the vehicle too, such as truly what it was for. As a general-purpose truck, it was no better than some wheeled options and more expensive. For air defense, the short range of the cannon was inadequate against helicopters. For reconnaissance, it was less useful than a lighter wheeled vehicle and it could not carry enough armor to be a useful armored vehicle. The Centaur truly seems to have died because it was designed without a clear role.

Sources

Land Rover Owner International May 2018
International Defence Review February 1979
Cullen, T., Foss, C. (1993). Jane’s Land-Based Air Defence 1992-1993. Jane’s Information Group
Laird. Centaur Multi-Role Military Vehicle. Sales Catalogues – unknown publication years

United Kingdom (1956)
Heavy Tank Destroyer – Design Only

Cerebos was a project designed by the 7th Tank Technical Officers (T.T.O.) Mechanical and Gunnery AFV design exercise held at the British Royal Armoured Corp (R.A.C.) School of Tank Technology (S.T.T.) in 1956. In the study, the designers were tasked with coming up with a heavy tank destroyer using guided anti-tank missiles as its primary offensive weapon. It had to be able to operate on the front lines of a European conflict, have relative immunity from Soviet guns at combat ranges, and a very high chance of scoring a direct hit and killing any Soviet vehicle of the day.

Background

The concept of a heavy and super-heavy missile vehicle had already been on the minds of British AFV designers for a few years during the early part of the Cold War. The Anti-Tank Guided Missile (A.T.G.M.) was a relatively new technology in an era when tank guns were still relying on ranging machine guns for calculating the distance to the target. The ability to effectively engage a tank at twice the effective range of such a gun and to effectively track and guide the missile to the target was highly desirable. This fact, combined with the huge leaps in armor penetration capabilities from shaped-charge (SC) technologies used in High Explosive Anti-Tank (HEAT) type warheads, especially compared to ‘conventional’ anti-tank ammunition of the period, made many think the era of the conventional armored tank was over. This was simply because, using conventional armor technologies, no tank could hope to survive against HEAT warheads such as the French SS.10, Soviet AT-1 Snapper, and later the Mosquito or Swedish Bantam. In order to stop such weapons, steel armor would need to have been over 500 mm thick, which in turn would have led to impractical machines. One result of this technological shift away from conventional armor was a generation of very lightly armored main battle tanks like the German Leopard. Whilst this shift was recognised early in Western nations, despite projects like the British Conqueror and some American heavy tank/tank destroyer projects, it took longer to be recognised in the Soviet Union, at least in the eyes of the West. Tanks like the IS-3 and T-10 loomed large in the imagination and nightmares of Western planners along with some incorrect assessments of the armor of a new generation of Soviet medium tanks. This meant that new means of countering this Soviet armor were needed.

The debate over the end of the tank has been waged since almost the very beginning of the weapon. For each new anti-tank weapon, a new defense innovation was found and, conversely, for each new step-up in armor, a new weapon to defeat this armor was found. In this way, to a broad extent, the evolution of anti-tank weapons very much reflected the evolution of tank armor. Within this context, there are few evolutionary leaps that were as profound in tank terms as this first decade or so after the end of WW2. The A.T.G.M. had gotten to the point where it was closer to forcing the tank into obscurity than ever before and, were it not for the vast fleets of tanks in Soviet service that remained an active threat forcing NATO to maintain its own significant fleet of tanks, armored warfare may have taken a very different route.

In the meantime, all nations were still churning out regular tanks expected to fight other tanks and so, much like the Second World War, tank destroyers were still being developed and built with the sole aim of breaking up enemy tank formations at long range. For the British, the appearance of heavy Soviet armor and the prospect of large enemy armored formations posed a particular threat. Many of those vehicles were virtually immune to the UK’s best tank-guns then in service and in such large numbers that even if they could match Soviet armor with British firepower they could still be overwhelmed.

There was little the British could do to counter the enormous numerical advantage of the Soviet forces in Europe but there was something which could be done about the guns and this fed into the motivation behind the development of the Royal Ordnance L7 105 mm rifled gun and eventually the L1 120 mm rifled gun too. Despite some heavy Anti-Tank concepts in the UK, the 7th T.T.O. Course opted instead for an A.T.G.M.-based Anti-Tank platform over a gun-based solution. The weaponry for this option consisted of a version of the Malkara missile, and this, it was felt, would provide the offensive power required to counter the Soviet threat. It also provided the additional benefit that the avoidance of a turret allowed all available protection to be focussed on the hull instead and all for less weight than a conventionally armed and armored gun-tank.

Cerebos

This was the context and logic behind the Cerebos, a turretless guided-missile tank destroyer with heavy armor. It was intended to operate on the front lines, have enough protection to withstand strikes from enemy tanks using conventional guns, and ideally use the chassis of a vehicle already in service as a platform. It was desired to have a missile able to destroy the heaviest Soviet vehicles then known in service or considered to potentially enter service. An ideal rate of fire of four rounds per minute was requested, with a minimum of two rounds per minute, with two missiles ready to fire at any time.

Layout

The goal was to reuse, as far as possible, the hull of an existing vehicle and Cerebos did just that and was based around a heavily modified Centurion tank. This meant a high degree of commonality of parts between Cerebos and the standard battle tank of the British Army of the day, which would reduce the logistical burden of the vehicle. The modifications, though, were extensive. Instead of the sloped glacis of the Centurion, Cerebos used a steeply angled ‘pike’ type nose, similar in style to that on the Soviet IS-3 tank. The driver sat along the centreline of the tank with a forward observation window cut directly out of the armor. The commander sat directly behind him, and the loader sat even further back on a swivel chair that allowed him the freedom of movement to assemble the missiles.

The missile bin had to be as equally protected as the vehicle itself and yet maintain a potential 360° arc of fire. This was somewhat problematic, as adding a conventional missile rack on the top of the vehicle would add not only excessive weight but would also result in a large and conspicuous target that would be vulnerable to small arms fire, shell splinters, etc. It would also be heavy, requiring dedicated hydraulics just to operate. To overcome these issues, the designers had the missile bins located inside the hull of the vehicle in a vertical arrangement, with 5 additional missiles stowed vertically running alongside the left and right sides of the inner hull. On firing the missile, the silo roof would fold open in two triangular parts. The weapon was then fired and guided on to its target by the commander. Once the missile was away, a new one was selected and attached to what amounts to a ‘potter’s wheel’ type base. This base rotated 360 degrees in the missile chamber, with the four fins being added from a separate supply located in front of each missile. This might seem odd as an idea, but the fins were the part of the missile which increased their storage volume and this semi-assembly of the missile attaching the fins meant that a larger number of missiles could be stowed inside the tank.

Protection

Cerebos was based on the Centurion but it was better protected from enemy fire than the Centurion. Sporting heavy frontal armor with a glacis plate 120 mm thick angled back at 65° and a lower front plate 120 mm thick angled at 55°, the Cerebos was felt to be well-enough protected to be able to take any reasonable enemy fire which might be forthcoming from the Soviet tanks of the day. In more conventional UK armor terms, the sides were still quite weak though, with just 25 mm on the upper sides (at 8°) tapering to 20 mm (at 10°) on the lower hull sides. The roof and rear were 25 mm thick, just enough for protection from small arms fire and shell bursts. The belly plate, just 20 mm thick, was sufficient to provide some protection from landmines but the focus of armor was on the front, facing the enemy, making the best use of the weight allowance available for maximum effect.

Automotive

Power for Cerebos was provided by a 9-liter Jaguar 90° V8 petrol engine delivering 350 b.h.p. at 3,750 rpm connected via a Merritt Brown 6-speed (4 forward and 2 reverse) gearbox. Drive was delivered, just like the Centurion – to the rear sprockets. This engine was expected to permit the 21-ton (21.3 tonnes) Cerebos to achieve a top speed of 28 mph (45 km/h) and operate for a maximum range of 220 km at 14 mph (22.5 km/h).

Armament

The primary armament proposed for Cerebos was a Manual Command to Line-Of-Sight (M.C.L.O.S.) type anti-tank missile that looked somewhat like a slightly smaller and sleeker Malkara missile, measuring 5 ft. (1.5 m) long and 10 inches (254 mm) in diameter. Unlike the High Explosive Squash Head (H.E.S.H.) warhead on the Malkara, this 20 lb. (9 kg) warhead was a shaped charge High Explosive Anti-Tank (HEAT) type. The total missile weight was expected to be 85 lb (38.5 kg) and these would be launched vertically from within the missile tube. Once assembled with its fins, it was ready for launching and this could be done whilst a missile was already underway as the targeting was being carried out by the commander with missile assembly taking place independently.

A pair of launchers and 12 missiles (two already assembled and ready to fire, with another ten stowed) could be carried. Although no performance data for these missiles was given, it can be estimated from the diameter of the warhead and the performance of contemporary missiles to achieve a penetration of approximately five times its diameter, which would equal about 750 mm of armor plate – more than sufficient to defeat any known Soviet tank in service at the time.

The maximum range for the missile was just as impressive as the anti-armor performance expected – far exceeding the range available from a conventional tank gun. Cerebos was to be able to engage targets at ranges of up to 6,000 yards (5.4 km), although the missiles did have a minimum safe distance as well – 500 yards (460 meters). With a flight-speed of 350 feet per second (107 m/s), the missiles had a potential maximum flight time of about 50 seconds. For ease of stowage, the missiles were kept without their fins. The gunner would have to assemble the bare missile, attach the fins individually by means of the snap-on fasteners and then load a missile into the missile bin. This whole process was estimated to take not more than 2 minutes per missile. This would mean (assuming two were already loaded) that up to 4 missiles could be fired in a 4-minute window.

Secondary armament for Cerebos was primarily for self-defense and consisted of a single Browning .30 caliber (7.62 mm) machine gun remotely operated from within the hull with a 360° degree arc of fire and provided with 4,250 rounds of ammunition. Six No.36 smoke dischargers were provided, with 3 per-side, and the crew was provided with grenades and small arms.

Conclusion

For its time and era, the wings being clipped on was nothing new and this type of missile-build-before-launch concept was also to be added into the FV4010 heavy missile vehicle, as the later fold out missiles and overall lighter materials were still some years away. Two flaws not raised in the original documentation but more observable with hindsight are the lack of a telescopic mast or periscope allowing firing from the reverse side of slopes and the poorly placed second cupola that had much of its view blocked by being located behind the first. Other issues are the commander acting as the missile gunner, guiding it to its target, placing undue stress, and preventing him from monitoring the battlefield. The Cerebos was no more than a design project and never built, however, many of the ideas and features later appeared on the Malkara launching FV4010.

Sources
Bovington Tank Museum Archives, STT section, Cerebos box

United Kingdom (1960s)
Experimental Turret – 3 Built

In recent years, thanks largely to erroneous publications and popular video games such as ‘World of Tanks’ and ‘War Thunder’, a comedy of errors has surrounded the history of the officially named ‘Centurion Mantletless Turret’. This redesigned turret – intended for installation on the Centurion – is often incorrectly identified as the ‘Action X’ turret, with the X being the Roman numeral for 10. It is also known as the ‘Action Ten’ or simply as ‘AX’. In turn, vehicles fitted with the turret, such as the intended Centurion, then have a false suffix attached to them, ‘Centurion AX’ being an example. There is also a false belief that the turret is associated with the FV4202 project, however as we will see, this is not the case.

But what is the truth behind the awkwardly titled ‘Centurion Mantletless Turret’? (for ease this will be shortened to ‘CMT’ throughout the article) Unfortunately, that is currently a hard question to answer, as much information surrounding the turret and its development has been lost to history. Thankfully, due to the efforts of amateur historians and Tank Encyclopedia members Ed Francis and Adam Pawley, some fragments of its story have been recovered.

The first falsehood to tackle is the name ‘Action X’. The name ‘Action X’ appeared in a book published in the early 2000s after the author cited seeing the name written on the back of a photo of the turret. What he fails to mention is that this was written in the 1980s, and does not appear in any official material.

Development

By the late 1950s, early 1960s, the FV4007 Centurion had been in service for over 10 years and had already proved to be a reliable vehicle, highly adaptable, and well-liked by its crews. In those 10 years of service, it had already been in use with two types of turrets. The turret of the Mk.1 Centurion was built to mount the famous 17-Pounder gun. It was roughly hexagonal with a gun mantlet on the leading edge. This gun mantlet did not run the entire width of the turret, but to the left-hand side was a step in the turret face with a large bulbous blister mount for a 20 mm Polsten cannon. The Centurion Mk.2 brought with it a new turret. While still roughly hexagonal, the large bulbous front was changed to a slightly narrower casting, with a mantlet that covered most of the turret face. The 20 mm Polsten mounting was also removed. Large stowage boxes were added to the outer circumference of the turret and gave the tank its instantly recognizable appearance. This turret would stay with the Centurion for the rest of its service life.

The FV4201 Chieftain was also in development in the early 1960s, and well on its way to becoming the British Army’s next frontline tank. The Chieftain featured a new mantletless turret design. The mantlet is a piece of armor at the breach end of the gun barrel that moves up and down with the gun. On a ‘mantletless’ turret, the gun simply protrudes through a slot in the turret face. With the Centurion proving to be a great export success, it was hoped the Chieftain would follow suit. The Chieftain was, however, expensive.

This would appear to be where the story ‘Centurion Mantletless Turret’ comes in. Evidence suggests that the turret was developed alongside the Centurion and Chieftain, as a means of creating a method for poorer countries to upgrade their Centurion fleets if they could not afford to invest in the Chieftain.

Overview

The design was quite different from the standard Centurion design, but it remained somewhat familiar to existing Centurion operators, foreign or domestic, making the transition easy on potential crews. A large sloped ‘forehead’ replaced the mantlet of the standard turret, with sloping cheeks replacing the vertical walls of the original. The coaxial Browning M1919A4 machine gun was moved to the top left corner of the ‘forehead’, with the aperture of the coaxial gun surrounded by 3 raised ‘blocks’ in the cast armor. The machine gun was connected to the main gun via a series of linkages.

The gun mount was designed to be adaptable and could carry either the Ordnance 20-Pounder (84 mm) gun or the more potent and infamous L7 105 mm gun, making it ideal for operators of both guns. The gun would pivot on trunnions placed in the slightly bulbous turret face, the location of which is identified by welded ‘plugs’ visible in the turret cheeks. The gun would be aimed via a unity sight that emerged from the turret roof, in front of the Commander’s cupola.

One of the things that the mantlet helps to protect from is shrapnel and debris entering the fighting compartment through the gun mount. In this mantletless design, plating was installed on the inside of the turret to ‘catch’ any fragments that made it through.

Internally, the layout of the turret was pretty standard, with the loader on the left, gunner front right, and the commander behind him in the right rear corner. The decision of what cupola would be equipped on the turret would likely have fallen to the end-user. For the trials, the turret was predominantly equipped with a ‘clam-shell’ type cupola – possibly a version of the Commander’s Cupola No.11 Mk.2. It had a domed two-piece hatch and around 8 periscopes and there was a mounting point for a machine gun. The loader had a simple flat two-piece hatch and a single periscope at the front left of the turret roof.

The turret bustle stayed the same basic shape, with mounting points for the standard bustle rack or basket. A feature carried over from the standard turret was a small circular hatch in the left turret wall. This was used for loading in ammunition, and throwing out spent casings. On both the left and right turret cheeks, there were mounting points for the standard ‘Discharger, Smoke Grenade, No. 1 Mk.1’ launchers. Each launcher featured 2 banks of 3 tubes and were fired electrically from inside the tank. The typical Centurion turret stowage bins were also installed around the outside of the turret, although they were modified to fit the new profile.

Unfortunately, most of the armor values of the turret are currently unknown, although the face is around 6.6 inches (170 mm) thick.

Not an FV4202 Turret

It is a common misconception that the ‘Centurion Mantletless Turret’ and the turret of the FV4202 ‘40-ton Centurion’ prototype are one and the same. The FV4202 was a prototype vehicle developed to test many of the features that would be employed on the Chieftain. However, these turrets are not the same. While they are extremely similar, there are noticeable differences.

The CMT is far more angular in its geometry compared to the FV4202 turret, which has a much rounder design. The cheeks of the CMT are straight angles where the FV4202 is curved. The trunnion holes on CMT are both in a downward angled section, while on the 4202 the slope is facing up. The armor ‘blocks’ around the coaxial machine gun are also shallower on the FV4202. It would also appear that the gun was mounted slightly lower in CMT. It is not clear as to whether there are any internal differences.

While the turrets are not identical, it is evident that they do share a similar design philosophy, both being mantletless designs with a similar placed coaxial machine gun.

Trials

Just three of these turrets were built, all of which took part in trials undertaken by the Fighting Vehicle Research and Development Establishment (FVRDE). Two turrets were mounted on a regular Centurion chassis and put through a series of tests. The remaining one was used for gunnery trials. While info on most of the tests has disappeared, details of the gunnery trial that one of the turrets – casting number ‘FV267252’ – underwent in June 1960 at the request of the ‘Turret’s and Sighting Branch’ are available.

The turret was subject to fire from rounds as small as .303 (7.69 mm) and .50 Caliber (12.7 mm), through 6, 17 and 20-Pounder rounds, as well as 3.7 in (94 mm) rounds. Both Armor-Piercing and High-Explosive rounds were fired at the turret. The results of the test are displayed below in an extract from the report ‘Trials Group Memorandum on Defensive Firing Trials of Centurion Mantletless Turret, June 1960’.

Conclusion

Of the 3 built, just one of the turrets – casting number ‘FV267252’ from the 1960 report – now survives. It can be found in the car park of the Tank Museum, Bovington. One turret has disappeared, while the other is known to have been destroyed in further firing trials.

Large chunks of the history of the Mantletless Turret remain missing, unfortunately, and the history we do know has been twisted and contorted. The name ‘Action X’ will no doubt continue to plague this turret for years to come, thanks in no small part to Wargaming.net’s ‘World of Tanks’ and Gaijin Entertainment’s ‘War Thunder’ online games. Both have incorporated a Centurion equipped with this turret into their respective games, identifying it as the ‘Centurion Action X’. World of Tanks is the worst offender, however, as they have also mated the turret with the hull of the FV221 Caernarvon and created the entirely fake ‘Caernarvon Action X’, a vehicle that never existed in any form.

Centurion fitted with the Mantletless turret equipped mounting the L7 105mm gun. Illustration produced by Ardhya Anargha, funded by our Patreon campaign.

Sources

WO 194/388: FVRDE, Research Division, Trials Group Memorandum on Defensive Firing Trials of Centurion Mantletless Turret, June 1960, National Archives
Simon Dunstan, Centurion: Modern Combat Vehicles 2
Pen & Sword Books Ltd., Images of War Special: The Centurion Tank, Pat Ware
Haynes Owners Workshop Manual, Centurion Main Battle Tank, 1946 to Present.
Osprey Publishing, New Vanguard #68: Centurion Universal Tank 1943-2003
The Tank Museum, Bovington

United Kingdom (1950-1957)
Heavy Self-Propelled Anti-Tank Gun – 3 Built (1 Stage 1, 2 Stage 2)

In the late 1940s, the British War Office (WO) was concerned that – after the debut of the IS-3 in 1945 – the Soviet Union would continue to develop heavily armored tanks. As such, the War Office filed a requirement for the development of a gun capable of defeating a 60-degree sloped plate, 6 inches (152 mm) thick, at up to 2,000 yards (1,830 meters), and a suitable vehicle to carry it.

This requirement led to the development of the ‘Ordnance, Quick-Firing, 183 mm, Tank, L4 Gun’, the largest purpose-built anti-tank gun to have ever been created. It was intended that this gun would be mounted on a new ‘Heavy Gun Tank’ based on the FV200 series chassis. This was designated the ‘Tank, Heavy No. 2, 183 mm Gun, FV215’.

A project was also launched to find a way to get the gun into action quickly on an existing hull. This could then be constructed quickly should the Cold War turn hot before the FV215 was ready.

This is where the FV4005 project comes in.

The Quest for Firepower

The development of the L4 started in 1950, and was aimed at increasing the firepower of the ‘Heavy Gun Tanks’. This was a uniquely British designation that was not governed by tank weight, but the size of the gun. A requirement was formulated for a tank armed with a gun capable of defeating a 60-degree sloped plate, 6 inches (152 mm) thick, at up to 2,000 yards (1,830 meters), a feat impossible even for the powerful 120 mm L1 gun of the FV214 Conqueror. By 1950, Major General Stuart B. Rawlins, Director General of Artillery (D.G. of A.) had concluded that there was no gun available with that level of ballistic performance and an investigation was launched. Initially, the British Military looked at the development of a 155 mm gun that would be standardized with the USA. However, even this lacked the required punch and, as such, 6.5 and 7.2 inch (165 and 183 mm respectively) High-Explosive Squash Head (HESH) shells were looked at.

At this time, the British Army came to the conclusion that a ‘kill’ did not necessarily mean the complete destruction of an enemy vehicle, and just damaging it was enough to take it out of action was enough. For example, a blown-off track is seen as a kill as it took the enemy vehicle out of action; today this is known as an ‘M’ (Mobility) kill. A ‘K’-Kill would be the destruction of a vehicle. The term used for this method at the time was ‘disruption not destruction’. The 6.5 in/165 mm HESH was not thought to be powerful enough to ‘kill’ a heavily armored target in this manner unless it hit bare armor plate. Attention, therefore, turned instead to the larger 7.2 in/183 mm shell which – Maj.Gen. Rawlins thought – would be powerful enough to render the target inoperable, and therefore ‘kill’ it, wherever it impacted.

The projected gun was designated the 180 mm ‘Lilywhite’. The background of this name is unknown. It may be an interpretation of the ‘Rainbow Code’ used by the WO to identify experimental projects. The ‘Red Cyclops’ flame gun attachment for the FV201, and the ‘Orange William’ experimental missile are examples of this. If this was the case, however, the name should be ‘White Lilly’. It may even simply be named after a Lieutenant Colonel Lilywhite of the Royal Army Ordnance Corps. It must be said that this is all speculation, and no evidence currently exists to support the theory.

It was not until December 1952 that the designation of the gun was officially updated to 183 mm. The design of the gun was accepted and was serialized as the ‘Ordnance, Quick-Firing, 183 mm, Tank, L4 Gun’. In reality, only the HESH shell underwent further development and the number of charges was dropped to one. The 183 mm L4 became one of the largest and most powerful tank guns in the world.

Background of the Project

From the start, the FV215 was the intended mount for the 183 mm gun, with development starting around the same time as the gun in 1950. The vehicle was based on the FV200 series chassis, with similarities to the FV214 Conqueror. The turret, however, was moved to the rear of the vehicle. The turret was capable of full 360-degree traverse, but it had a limited firing arc due to the size and power of the gun. This ‘Heavy Gun Tank’ would take a while to develop, so, in November 1950, the WO filed a requirement for a stop-gap vehicle capable of carrying the weapon into service should hostilities erupt before the completion of the FV215. A similar connection can be found with the Conqueror and the FV4004 Conway.

Following the end of General Rawlins’ investigation, and with some degree of urgency to get the 183 mm gun into service as quickly as possible, a carrier design was finalized, as this extract from a 1951 ‘AFV Development Report’ describes:

“A limited traverse, lightly armoured S.P. mounting based on the Centurion hull and weighing some 50 tons[*]. This would be known as F.V.4005 and could be in production by December 1952. Because of the use of parts in existing production, it was considered that quick limited production could be achieved. It was also clear that much would be learned about the hitherto unknown art of mounting so large a gun as an S.P. mounting.”

*50 long tons. Long tons are a unit of mass unique to the United Kingdom; for ease, it will be shortened to ton when used again. 1 long ton is equal to about 1.01 metric tonnes, or 1.12 US ‘Short’ tons.

The design of the vehicle would be held in limbo, ready to go into production if necessary. This stopgap vehicle would be based on the Centurion of the FV4000 series, with the original turret removed. The vehicle would go through two ‘Stages’ or ‘Schemes’. ‘Stage 1’ was built to test the gun and its mount on the Centurion chassis. The ‘Stage 2’ was a finalized design and would be the production standard. The vehicle was given the designation of ‘Heavy Anti-Tank, SP, No. 1’ – ‘SP’ standing for ‘Self-Propelled’. Officially, the FV4005 was never given the traditional British ‘C’ name such as the FV4101 Charioteer and FV4004 Conway before it. However, extensive account files of Vickers Ltd. from 1928 to 1959, shed some light on what it may have been. This particular extract – graciously provided by researcher Ed Francis – is from December 1952:

“Design and manufacture of equipment for mounting 180 mm gun on “CENTAUR” Tank – FV4005. Trials have now been carried out at Ridsdale and certain modifications to design have been found necessary… ”

In total three prototypes were ordered – a single Stage 1, and two Stage 2s. The FV4005 would fill the role of a ‘Heavy Gun Tank’. As such, the vehicle would engage targets from long-range, firing over the heads of attacking lighter tanks.

The Centurion Hull

The Centurion was chosen as the basis for this vehicle and three Mk.3 hulls were removed from service for the prototype development. Other than the removal of the turret and various small additions, the hull would remain mostly unaltered. Armor on the hull remained the same thickness, with about 3 inches (76 mm) at roughly 60 degrees on the front slope. A 650 hp Rolls-Royce Meteor petrol engine, located at the rear of the vehicle, propelled the tank. The Centurion used a Horstmann style suspension, with 3 bogies per side carrying 2 wheels each. The drive sprocket was at the rear with the idler at the front. The driver was located at the front right of the hull.

Details of the 183 mm L4

Just a small number of the ‘Ordnance, Quick-Firing, 183mm, Tank, L4 Gun’ were built, but it is unclear just how many. Records suggest at least 12 were built. Unfortunately, the exact length of the 183 mm gun is currently unknown, but it was somewhere in the region of 15 feet (4.5 meters) long. It was fully rifled with a large ‘bore-evacuator’ (fume extractor) placed roughly half-way down its length. The gun alone weighed 3.7 tons (3.75 tonnes).

High-Explosive Squash Head (HESH) was the only ammunition type to be produced for the 183 mm gun. Both the shell and the propellant case were of gargantuan proportions. The shell weighed in at 160 lbs. (72.5 kg) and measured 29 ¾ inches (76 cm) long. The propellant case weighed 73 lbs. (33 kg) and measured 26.85 inches (68 cm) long. The case contained a single charge that propelled the shell to a velocity of 2,350 fps (716 m/s). When fired, the gun produced 86 tons (87 tonnes) of recoil force and had a recoil length of 2 ¼ feet (69 cm).

HESH shells have an advantage over regular kinetic energy rounds as their effectiveness does not decrease with distance. This shell works by creating a shockwave on detonation. Once this wave reaches a void, it reflects back. The point at which the waves cross causes tension feedback which rips apart the plate, carrying a scab with approximately half the kinetic energy forwards, scattering shrapnel around the interior of the target. Test firing of the L4 against a Conqueror and a Centurion proved how powerful the round was. In two shots, the 183 mm HESH shell blew the turret clean off the Centurion, and split the mantlet of the Conqueror in half. HESH could also serve as a dual-use round just as capable of engaging enemy armor as for use as a high-explosive round against buildings, enemy defensive positions, or soft-skinned targets.

Stage 1

In a 1951 Ministry of Supply: Fighting Vehicle Division ‘AFV Development Report’ – regarding the development of an AFV mounting of the 183 mm gun – the ‘Stage’ or, ‘Scheme 1’ is described as such:

“Embodies a concentric recoil system in a mounting in trunnions on an undercarriage, the whole of which rests on the existing turret race rings. No crew protection is provided and one prototype only will be made to obtain experience of firing such a large gun from the Centurion hull.

It is anticipated that although all round traverse will be possible, firing will be confined to a limited angle forward on either side of the fore and aft line.

Prototype should be completed by 31st December, 1951”

The Stage 1 was built as a test vehicle, as such, it lacked a few components. On the Stage 1, a bespoke platform was constructed that was installed over the original turret ring. This platform was a solid floor, did not incorporate a basket, and was not, in any way, enclosed. The L4 gun was installed in a rigid mount and was completely fixed in elevation. The platform was capable of full horizontal traverse, but firing would be restricted to a limited arc over the front and rear of the vehicle. As mentioned in the report, the gun used a concentric recoil system. This utilized a tube placed around the breech end of the barrel, acting as a space-saving alternative to traditional recoil cylinders.

Space on the platform was limited, as such, there were only positions available – presumably – for the gunner and loader. The gunner was seated on the left of the gun in a well-padded seat complete with a back-rest. Behind him was a large rack for ammunition stowage. The fact that the gun was fixed in elevation allowed the installation of a mechanical ‘loading assist’ device to help the loader handle the combined 233 lb (105.5 kg) weight of the ammunition by aligning it with the breach. This was not an automatic loader as it lacked a rammer. There was no seat for the loader. The driver’s position – the front right of the hull – was unchanged.

The only other changes to the Centurion hull were the addition of a large recoil spade at the rear and a large folding travel lock or ‘gun crutch’ to use the British term. The spade was used to transfer recoil forces from the chassis directly to the ground, easing the strain on the suspension. When the vehicle was in position, it would be lowered to the ground. When the gun was fired, the spade provided a back-stop by digging into the ground.

The ‘Stage/Scheme 1’ was subjected to numerous firing trials. Despite some issues with the concentric recoil system, the trials were a general success. Work then progressed to the ‘Stage/Scheme 2’ vehicle.

Stage 2

In the same 1951, Ministry of Supply: Fighting Vehicle Division ‘AFV Development Report’, the ‘Stage/Scheme 2’ was described as the following:

“Embodies two conventional recoil systems with a hydropneumatic recuperator and an independent run out control. Undercarriage similar to above [Stage 1] but of fabricated construction.

A superstructure for crew protection will be provided but weight considerations will preclude more than a limited degree of splinter protection.

A sight is being designed in which the body is fixed with relation to the gun mounting, and internal moving parts apply angle of sight, target elevation and correction for trunnion tilt. The range scale is visible in the sight eyepiece.

Layout designs have been prepared and details will be completed shortly.

A prototype should be available by March, 1952.”

The Stage 2 was built closest to what a production version of the FV4005 would consist of. As such, a number of changes were made between the two Stages. The biggest change was the design and construction of a fully enclosed turret to the form of little more than a large box. The loading assist for the loader was also deleted, and the concentric recoil system was replaced by a hydropneumatic type.

The turret was welded and fabricated from ½ inch (14 mm) thick steel and was there to protect the crew from small arms fire and shell splinters. As this was intended to be a second line vehicle that would keep out of the range of enemy AFVs, the FV4005 did not need really thick armor. Also, with the addition of this impressive gun, the chassis and engine could not take any extra weight. The turret was split into two parts: a sloped face and a completely boxed rear end. The turret face was mantletless, with a large face-plate angled at a very shallow angle. The cheeks were also slightly angled. These angled sections terminated in completely vertical turret walls and a flat roof. The roof stepped up as the rear section of the turret was taller and box-like, with external structural ridges. Internally, this rear section was where the ammunition was stowed against the walls. In total, 12 rounds were carried.

There were two hatches on the roof and one large door on the rear. The roof hatches were two-piece and, in front of them, were two single periscopes installed in the turret roof. The large rear door was used for crew access, but it was also used for ammunition resupply via a winch and rail. Charges would be placed on the rail and then winched into the turret. Turret crew would consist of four men including the gunner and commander. As the loading assist of the Stage 1 was deleted on the Stage 2, two loaders were required. One loader would handle the charge, the other the projectile.

On the turret face, to the left of the gun, was a large square bulge. This was the housing for the primary gun sight. The particulars of this sight are unknown, however, there is a suggestion that it was based on the TZF-12A of Panther fame. This, however, cannot be corroborated. While the turret was capable of full 360 degrees horizontal traverse, firing was limited to a limited arc over the front and rear of the vehicle. This was a safety feature necessitated by the power of the gun.

Like the Stage 1, the Stage 2 featured a recoil spade installed at the rear of the vehicle. However, on the Stage 2, a hand-cranked winch was installed on the rear of the vehicle to lower the spade.

Like the Stage 1, the Stage 2 went through a number of firing trials. Where the Stage 1’s concentric recoil system suffered some faults, the Stage 2’s more typical hydro-pneumatic system operated without issue. In total, 150 rounds were fired during the tests at Ridsdale, Northumberland. In a 1955 Fighting Vehicle Division ‘AFV Development Liaison Report’ of the Ministry of Supply it is stated that: “General functioning [of the Stage 2] has proved satisfactory”.

Fate

Despite the general success of the project, the FV4005 suffered much the same fate as the FV215. The feared Soviet heavy tanks, like the IS-3, which these vehicles were designed to defeat, were not being made in the massive numbers expected, indicating a shift in policy to lighter, more maneuverable, and more lightly armored tanks. The need for ‘Heavy Gun Tanks’ like the Conqueror, FV215 and the FV4005 stand-in, from this perspective, was simply becoming absent. Other changes were also taking place as technology-wise, larger caliber guns with their huge ammunition were becoming obsolete by improved anti-armor performance of smaller guns and by the appearance of a new generation of accurate Anti-Tank Guided Missiles (ATGM).

The FV4005 project was officially canceled in August 1957, around the same time as the FV215. The three constructed prototypes were divided between various establishments. The Stage 1 was given to the Shoeburyness Proof and Experimental Establishment where the turret was removed and the Centurion hull returned to service. One Stage 2 was offered to the Royal Military College for Science, while the Fighting Vehicle Research and Development Establishment (FVRDE) kept the other Stage 2. The Centurion chassis were also likely returned to service. At some point, one of the turrets found its way to The Tank Museum, Bovington, where it sat alone for a number of years before being mated with a spare Centurion hull owned by the Museum. The vehicle now sits as a ‘Gate Guardian’ outside the museum, alongside a Sherman Grizzly.

Illustration of the FV4005 Stage 1 with the open top gun platform, produced by Pavel Alexe.

Illustration of the FV4005 Stage 2 with enclosed turret, produced by Pavel Alexe, based on work by David Bocquelet.

Both Illustrations were funded by our Patreon campaign.

Sources

2011.2891: Ministry of Supply: Fighting Vehicle Division, AFV Development Progress Report, 1951, The Tank Museum, Bovington
2011.2896: Ministry of Supply: Fighting Vehicle Division, AFV Development Liaison Report, 1955, The Tank Museum, Bovington
2011.2901: Ministry of Supply: Fighting Vehicle Division, AFV Development Liaison Report, 1957, The Tank Museum, Bovington
Vickers Ltd. Account Records, 1928 to 1959 (Provided by researcher, Ed Francis)
Bill Munro, The Centurion Tank, The Crowood Press
Pat Ware, Images of War Special: The Centurion Tank, Pen & Sword Books Ltd.
Simon Dunston, Haynes Owners Workshop Manual, Centurion Main Battle Tank, 1946 to Present.
Simon Dunston, Osprey Publishing, New Vanguard #68: Centurion Universal Tank 1943-2003
David Lister, The Dark Age of Tanks: Britain’s Lost Armour, 1945–1970, Pen & Sword Publishing
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