Category: Cold War British MBT 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