Vickers Mk.7/2

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.

Vickers Mk.7/2
Crew	4 (driver, gunner, loader, commander)
Dimensions	10.95 m long (with gun), 9.77 m (gun to the rear), 7.72 m (hull length only), 2.54 m high (turret roof), 2.99 m (top of commander’s sight), 3.42 m wide (without side armor packs, 4.945 m of track on the ground.
Ground Clearance	0.5 m
Weight	55,000 kg
Engine	German MTU 873 12-cylinder diesel engine delivering 1,500 hp at 2,600 rpm
Speed	80 km/h top speed on a good surface. Up to 60.3 km/h cross country(road). Very soft sand 39.4 km/h.
Suspension	Torsion bar
Armament	L11A5 120 mm rifled main gun, coaxial 7.62 mm or 12.7 mm machine gun, roof-mounted remote-control 7.62 mm or 12.7 mm machine gun. Rheinmetall 120 mm smoothbore.
Armor	steel base hull and turret with Chobham armor arrays across frontal 60-degree arc.
For information about abbreviations check the Lexical Index

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