United Kingdom (1950)
Heavy Tank Project – None built
Chimera began as a design exercise in April 1950 at the School of Tank Technology (STT) to design and draw up the plans for a tank capable of engaging and destroying the Soviet IS-3. The Soviet behemoth had first shown up in numbers at the Berlin Victory Parade of September 7th, 1945 and the British tank industry began working overtime to come up with new and innovative ways to tackle this tank, as it appeared to render all British designs at the time relatively obsolete.
Requirements – How to Beat an IS-3?
Individual firms, such as Vickers and Leyland, began to look at ways to quickly mount 120 mm guns onto existing hulls, while Chertsey and the STT looked at other ideas and design exercises. The course looked at the IS-3 and evaluated what they knew about it. Instead of focusing on what was good, they looked at what was bad and how these issues could be improved upon in a British counter.
The issues highlighted several areas, notably the omission of refinement, lack of crew comfort, low power-to-weight ratio, and its limited ammunition count. The team set about a design that could overcome these issues and try to match its better aspects. The team realized that, in order to overcome the faults found in the IS-3, the Chimera would need to weigh 55 long tons (55.9 tonnes) and have a crew of four. The designers were convinced that although 55 long tons was ten long tons heavier than IS-3, the installation of a powerful engine, increased crew space, additional ammunition capacity and other capacities such as gun handling would compensate for the higher profile and weight gain.
The Chimera was also to feature set design criteria that included a low maintenance score i.e. be quick to fix with minimal costs or resources and ideally a small training curve for ease of operation and a training program that was forgiving for new crews.
In order to overcome the IS-3, the Chimera needed to mount a weapon able to penetrate 120 mm of armor at 2,000 meters and, if possible, be multirole, able to tackle both armored targets and provide adequate support against soft targets or fortified positions.
For defensive purposes, Chimera was to have enough armor to survive being hit by the IS-3 at 1,000 meters. The designers calculated that the 122 mm gun had 173 mm of penetration at 1,000 meters.
Finally, it was noted that the IS-3 was underpowered or lacked agility on the battlefield and therefore Chimera was to have as large an engine as possible, and not less than 1,000 bhp to give it an advantage in the mobility department.
Several weapon layouts were considered. The initial idea was for a 120 mm ADPS firing rifled gun which was discarded as it was calculated that in order to achieve a 100% chance to penetrate the IS-3 at 2,000 meters, the round would need to be traveling at 4,000 fps, which was not possible to achieve in a gun the size and weight required for Chimera. They, therefore, chose to go with a large rifled weapon designed to fire High Explosive Squash Head (HESH) as its primary ammunition, with High Explosive (HE) and High Explosive Anti-Tank (HEAT) as secondary rounds. HESH would suffer no loss of performance over distance and double up as an effective secondary round at the same time.
The amount of Plastic Explosive (PE) filler to overcome the armor on the IS-3 was estimated at 24 lbs (10.8 kg) and, with an average of 40% filler, would require a 60 lb (27.2 kg) shell from a gun with a caliber of at least 5 inches (127 mm). It was desired that the gun be mounted rigidly, meaning that it would have no recoil mechanism and would be mounted rigidly to the turret, but could still go up and down. Also, a Centurion-like mantlet was to be avoided. This may have been designed in order to save space and internal volume and other UK vehicles had had problems when trying to mount 120 mm guns. Secondary weapons were to consist of machine guns either coaxially mounted, pintle-mounted, or even a bow gun configuration, although the latter was quickly dropped. A pair of Campbell smoke dischargers were also chosen for screening purposes. The issue of obscuration was raised, however, and the team looked at various bag charges and settled on a relatively smokeless charge that would alleviate a lot of the issues but no bore evacuator or muzzle brake was to be fitted and a limited amount of obscuration would be present.
The armor thickness was matched quite closely to that of the IS-3, at least on paper. The designers estimated the Soviet turret to be 200 mm thick at the front, and so, Chimera’s was to be 8 inches (203 mm) correspondingly. They did not know what the turret side of the IS-3 was and chose Chimera’s to be 3” (76 mm). The Chimera team estimated the IS-3 to have 120 mm of frontal armor at 55°, however, they did not appear to have taken into consideration the secondary angle of the pike nosed design which gave it in excess of 200 mm of effective thickness from the front, providing the hull was facing the shooter. In response to this, Chimera’s frontal plate was 114 mm thick at 55° for 199 mm of effective protection.
The IS-3 did have thicker side armor with its 45° sloped inner side offering 90 mm of protection to the 75 mm of Chimera that tapered to 50 mm at the rear, although this was nearly twice as thick as many British tanks that often had to rely on only 40 mm of side armor. The IS-3 did offer better protection on the roof with 60 mm to the Chimera’s 25 mm and both had similar belly plates of about 25 mm.
The IS-3 was armed with the powerful D-25 122 mm AT cannon which, at combat ranges (1,000 meters), could perforate 158 mm of Rolled Homogeneous Armor (RHA) with its BR-471 Armor Piercing High Explosive (APHE) rounds or 180 mm with Armour Piercing Capped Ballistic Capped (APCBC) rounds, forcing the IS-3 to close to around 500 meters to be combat effective. The 120 mm High Explosive Squash Head (HESH) from the Chimera would have scabbed up to a maximum depth of 375 mm, but an optimal armor depth of 100-200 mm would have resulted in a large amount of spall and the relative thickness of the IS-3 frontal plate having little to no effect on the hypersonic shockwave.
The next comparison the team made was in engine power. The IS-3 was considered underpowered with what they believed to be a 520 hp engine and a top road speed of 40 km/h and to that end they decided to go with a 1,040 bhp engine which would give it about 18 hp/ton and a top speed of 50 km/h on roads. This maneuverability advantage would give the Chimera the edge in choosing where and when to strike.
The dimension comparison between Chimera and IS-3 was a bit of give and take. Chimera was somewhat shorter at 28.5 ft (8.6 meters) to the IS-3’s 32.3 ft (9.8 meters), but also slightly wider at 12 ft (3.6 meters) to 10.6 ft (3.2 meters). Chimera and IS-3 were relatively even on the height measurements, with the former being 9 ft (2.7 meters) to the IS-3’s 8ft (2.4 meters) but had better gun depression of -10 degrees to the Soviet’s -3 degrees.
Although the Chimera was never built, it did show the need for a large 120 mm or greater gun. It also showed that HESH would also feature heavily in the destruction of these Soviet tanks, a fact that remained true until the Soviet adaptation and integration of composite armor much later. They also assumed, correctly, that the Soviet layout was inferior to a more conventional system as later analysis of a captured IS-3 proved the limited hull space to be cramped and uncomfortable over any long period of time. Where the designers did go wrong was on the armor calculations and eventually the Soviets replaced the IS-3 with the heavier T-10 tank, and later the T-55 and T-62, both of which would have no difficulties in destroying Chimera at an equivalent range.
It should be noted that there are several ‘Chimeras’ in School of Tank Technology designs as certain names (especially those beginning with ‘C’) crop up several times over the years the school was in service. It would not appear that the name was specifically reserved for one class of type or course and one can surmise that this appears to be based purely on the UK not being willing to throw a good name away.
Chimera heavy tank specifications
5 inch 2,400 fps 127 mm QF rifled gun
40 rounds HESH and HE
2 x .300 Robinson machine guns
1 x No 19 and 1 x No 88, 1 x Infantry telephone.
Road 155 miles, off-road 93 miles
Meteor Mk XI Supercharged 1,040 hp
Borg and block triple plate
Synchronized Merritt Brown
211 UK Gallons
25 UK Gallons
? UK Gallons
Power to weight ratio
Number or road wheels
Horizontal Helical Sprung
Height of Idler from rear ground
30 inches (76cm)
Length of track on ground
163.2 inches (4.1 meters)
20 inches (50.8 cm)
12 ft (3.6 meters)
9 ft (2.7 meters)
28.5 ft (8.6 meters)
Vertical obstacle crossing
3.5 ft (1.06 meters)
10.5 ft (3.2 meters)
To hull top
Glacis plate: 4.5 inches @ 55° 198 mm
Nose plate: 4.5 inches @ 55° 198 mm
Bottom plate: 1 inch (25 mm)
Side hull plates: 2 inches + 1 inch on first ¾ (76 – 50 mm)
Hull rear: 2 inches (50 mm)
Hull roof: 1 inch (25 mm)
Turret Mantlet: 8 inches (203 mm)
Turret Front: 8 inches (203 mm)
Turret Sides: 3 inches (76 mm)
Turret rear: 3 inches (76 mm)
Turret roof: 1 inch (25 mm)
United Kingdom (1984 – 1986)
Cold War MBT – None built
The Newcastle-based firm of Vickers Defence Systems had been building tanks on Tyneside for decades but had struggled in the 1980s to find markets for its tanks. With the unveiling of the Chobham armor technology in 1976 and Vickers being brought into the committee on its use, they obviously wanted to make use of this latest protection technology for their own tanks to try and meet the new export markets. The first attempt to move beyond the otherwise very competent Mk.3 design was the Mk.4, later reworked and known as the Valiant. The Valiant was a solid design with several significantly advanced features such as the all-aluminum hull and brand new fire-control system. When the Valiant failed to receive any orders, plans were put in place to upgrade the mobility aspect of the vehicle, but the hull was lost to an accident leaving just the turret needing a new body. A solution proposed was to use the already in production Challenger 1 hull for this to create a brand new tank – the Vickers Mk.7.
The Mk.7 started life as a goal to combine Chobham armor technology with the experience gained in the production of the Mk.3. The first attempt had been the Mk.4, a new turret made from cast steel with Chobham armor and an all-aluminum hull. That project was let down very early by the RO L7A3 105 mm gun which, despite being an excellent gun in its own right, was simply inadequate for the modern battlefield with a new generation of Soviet tanks like the T-72 fielded and exported in increasingly large numbers. The Mk.4 turret, therefore, was redeveloped quickly to be a ‘Universal’ Turret, one with a carefully designed mounting able to take the L7A3 105 mm, the L11A5 120 mm, and even the German 120 mm smoothbore. In this way, it could appeal to both first-world armies who wanted a 120 mm gun and also to an export market where a 105 mm gun might be considered a cost-effective alternative. The vehicle was quickly rebranded as the Valiant.
The Valiant had also included a state-of-the-art suite of fire control making it a very potent machine for delivering firepower on the battlefield. Its drawback had been an automotive one and despite plans in hand for an improved version, an accident wrecked the hull.
With the loss of the Valiant hull, ideas for improvements based on the Valiant’s automotives had to be shelved, as there was no budget to design and build a new hull. Instead, the work was done to salvage the turret, repair the optics, and hunt for a new hull with hopefully some improved mobility.
The first candidate for this new hull was that of their direct opposition, the Challenger I hull of ROF Leeds. Their proposed marriage would have been the first instance of the Vickers Mark 7, but it never got further than a proposal.
The optics for the Universal Turret were state of the art for the time. Firstly, 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 stabilised panoramic (360 degreesdegree) sight. This sight had various magnification modes, x3 and x10 and incorporated ana Nd-YAG-type laser rangefinder. In addition to this was 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 L30 x10 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 instrumenta Vickers instruments GS10 periscopic sight for target acquisition. The loader was provided with a single AFV No.10 Mk.1 observation periscope. The driver’s optics consisted of a single wide-anglewide angle episcope in the centre-front of the hull
The Universal Turret was able to mount a choice of main gun with the two primary options being the British 120 mm L11A5 rifled gun or the German 120 mm smoothbore from Rheinmetall with ammunition storage in the hull, turret bustle, and with a ready rack in the turret basket.
Elevation for the main gun was limited to -10 to +20 degrees and, loaded manually, the rate of fire was given as 10 rounds per minute (1 every 6 seconds) with the British 120 mm gun. 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 stabilisation system was an all-electric system developed by Marconi. This system 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 machine Hughes chain 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.
The turret was large and rectangular with vertical sides and an angled front made from flat panels and with the gun located centrally on the front 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 which 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 aluminium plating and also contained the ready-ammunition stowage. The turret sat on the Challenger 1 hull which was conventionally arranged with the driver in the front, fighting compartment in the middle on top of which the turret sat, and engine compartment in the rear.
The turret was a steel base structure and, although the exact makeup was never released, it should be borne in mind that the original Valiant (or Mk.4 originally as it was) was based on the technology from the Mk.3. The Mk.3 had moved from an all-welded steel turret to a cast one to improve ballistic protection and, although the technology for the Mk.4 followed much of the lessons from the Mk.3, it appears to have switched back to an all-welded turret in order to accommodate the block-like Chobham armor packs on top. This would be in contrast to the Challenger 1, then coming into service, which used a front half made from a complex steel casting and welded rear portions with the Chobham packs over the front and sides.
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 centre 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.
The hull used heavy sections of Chobham across the front and sides with the driver sat recessed within the armour at the centre-front of the tank. Spaced armour covered most of the upper sections of the hull and all this combined to make the Challenger 1 one of the best protected tanks of the era.
Tracks and Suspension
The tracks and suspension for this vehicle were identical to those on the Challenger 1, with 6 large road wheels, each on a swing arm. Each wheel had a rubber tyre and ran on steel tracks fitted with removable rubber pads. The suspension was an improvement over the torsion bars of the Valiant and consisted of hydropneumatic units.
Power for the vehicle was provided by the Rolls Royce CV12 26-litre diesel engine located in the rear of the hull. Producing 1,200 hp and delivering it through a David Brown TN37 automatic transmission with 4 forward and 3 reverse gears. As the complete Challenger 1, the vehicle had a top speed of 56 km/h and with the new turret would be around the same weight so likely a very similar performance as well.
The Rival and the Name
At this time, around 1983, Vickers Defence systems was a direct rival to the Royal Ordnance Factory Leeds which was producing the Challenger 1 MBT. The Challenger 1 was just entering service with the British Army as the replacement for the Chieftain. Both the Valiant and Challenger 1 had already been rivals during British Army trials in 1982 and, despite more capable the fire control system of the Valiant, the Challenger had won out. Vickers were left needing a new foreign market for the tank and a new hull. Asking for a joint partnership with ROF Leeds to use the Challenger 1 hull when ROF already had the Challenger in production and were seeking overseas orders was simply not viable and, understandably, the project ended before it even began. When the solution appeared in the form of the Leopard 2 hull being made available from the German firm of Krauss-Maffei, the turret found a new lease of life as the Mk.7/2, implying that Mk.7 was just to be the original Valiant turret/Challenger hull combo or that Mk.7 was the general ‘fit the Valiant turret onto an MBT platform’ project name.
Given that when the Mk.7/2 was unveiled, it was identified as the Mk.7, it is logical to assume the latter and that the ‘2’ was added retrospectively.
It is with some irony perhaps that in Egypt, in 1985, the Mk.7/2 was tested against the rival Challenger 1 and the fire control system once more proved itself to be superior to that of the Challenger 1, which was suffering from issues with firing on the move and engagement speed.
As it turned out, the Egyptians bought neither the Mk.7/2 nor the Challenger 1, and less than a year later Vickers Defence Systems bought the ROF Leeds plant and with it the rights to Challenger 1 and was awarded contracts for the Challenger-based Armoured Repair and Recovery Vehicle (C.A.R.R.V.).
At the same time, Vickers also acquired tank-design authority from Royal Armament Research and Development (RARDE) at Chertsey. Vickers, by 1986, therefore had all of the cards with the exception of the superior turret from the Valiant – that was repackaged and sold off to Brazil for their EE-01 Osorio. Instead of simply trying to get the British Ministry of Defence to replace Challenger 1 turrets with the Valiant Universal Turret as envisaged in 1984, Vickers had other plans.
In 1986, just a year after taking over ROF Leeds, Vickers submitted a completely unsolicited plan to the MOD for a new tank to replace the Challenger 1. At a time when the Challenger 1 was brand new in service, this was certainly a bold move. Development of the Challenger 2 was to start thereafter and a working prototype was ready by the end of 1989. The Challenger 2 was a completely new tank despite sharing a name and general shape with the Challenger 1 and built-in much of the preceding years’ worth of knowledge gained by Vickers. Development of the Challenger 2 finally gave Vickers the Chobham-armored tank they had wanted and started nearly a decade earlier.
Resolving the key problems with the Challenger 1, the Challenger 2 more than anything else perhaps best illustrates the potential Vickers had offered way back with the Valiant but which had been lost. The Valiant turret with the Challenger 1 hull would have resolved the fire control issues with the Challenger but it did not really resolve the mobility problem. The Mk.7/2 on the other hand, resolved the mobility problem but was stymied by the fact that the German government limited exports of the Leopard 2 tank hull. Having suggested using the Valiant turret on the Challenger 1 and being rejected, Vickers had simply moved on to a design to replace the Challenger so that, when they took over control, changing the turret on the old hull would not suffice. Instead, the new tank would improve on the old one in all areas.
4 (driver, gunner, loader, commander)
Rolls Royce CV12 26-litre diesel engine producing 1,200 hp
56 km/h (road)
190 km (118 mi)
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.
Welded steel and Chobham
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
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.
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.
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.
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.
SPARTAN: Royal Military College of Science.
Discussions with Lucian Stan regarding radiation penetration
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 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.
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.
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
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.
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.
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.
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.
Specifications (Laird Centaur)
5.62 long x 2 m wide, height varied by model
Total weight, battle ready
3.05 tonnes empty
1 + other (Driver plus crew depending on body)
115 kW Rover 3.5 litre V8 petrol producing 1260 Nm of torque at 2,500 rpm
80 km/h (road)
700 km (road)
Various including: HOT / MILAN anti-tank guided missiles, Oerlikon GAM-BO 20 mm cannon, 20 mm Rheinmetall Mk. 20 Rh 202, 7.62 mm machine guns, 120 mm Wombat anti-tank rifle
Protected fuel tanks, 5 mm hull floor anti-mine protection as standard. Other ballistic protection options available
Semi-elliptical leaf springs and shock absorbers for wheels (front), modified (shortened) CVRT Scorpion tracks (rear)
70% gradient (31.5 deg. slope)
Tilt Angle (side slope)
100% gradient (45 degree)
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.
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.
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.
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.
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.
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).
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.
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.
Bovington Tank Museum Archives, STT section, Cerebos box
21ft 5.5 inches x 9ft 10 inches x 8ft 4 inches (6.53 x 3.00 x 2.54 m)
3 (commander/gunner, driver, loader)
Jaguar 9 liter 90° V8, 350 bhp
28 mph (45 km/h)
17 inches (0.43 m)
Track Center Distance
8 ft. 4 inches (2.54 m)
Length of Track on Ground
14 ft. 7 inches (4.45 m)
Normal ground pressure
8.4 psi (57.92 kPa)
Vertical obstacle crossed
3ft 8 inches (1.12 m)
7ft (2.13 m)
Manual Command to Line-Of-Sight (MCLOS) ATGM
0.3/7.62 mm MG
Maximum, Minimum Missile Range
6000 yards/5.4 km, 500 yards/457 meters
350 fps (107 m/s)
12 High Explosive Anti Tank Missiles
Front: 120 mm @ 65 degrees
Sides: 25-20 mm
Rear 25 mm
Bottom 20 mm
The final decades of the Cold War saw a generational change in Western tanks as they faced off against the armies of the Warsaw Pact across Central Europe. The Soviet-led forces were dominated by tanks such as the T-55, T-72 and variants of both, and there were continuing concerns over even newer Soviet tanks with improved armor and firepower. The Western tank armies of NATO were dominated by an older generation of tanks in a long and slow process of improvement and replacement: the British wanted a replacement for the Chieftain, the Americans were replacing the aged M60 with the new M1 Abrams, and the Germans were replacing the Leopard I with the Leopard II. Much of that Western generational change from tanks based on steel armour had come about as a result of the British development of a new type of armor, announced in June 1976 as ‘Chobham’. A whole new level of protection for Western tanks promised to provide a true qualitative edge in protection over their Soviet contemporaries. With this new armor, and a need for a replacement for Chieftain urgently required, there was a clear opportunity for a large and lucrative contract for a new main battle tank for the UK, and potentially for export.
Based in Newcastle-Upon-Tyne in the northeast of England, engineers at the British firm of Vickers, with decades of tank building experience, were, at this time, developing a new ‘conventional’ tank for the export market: the Mk. 3. Using the availability of this new Chobham armor, they applied that knowledge to their Mk. 3 to produce one of the first of this new generation of tanks moving away from tanks reliant solely on steel armor, analog fire control and ranging to a new era of enhanced protection and digital fire control. Originally simply referred to as the Mk. 4, it soon gained a much more marketable name, the Valiant.
The Valiant followed a conventional layout with the driver in the center of the front of the hull, the turret roughly central, and the engine in the back. On top of the hull was the large rectangular turret 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, and 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.
Work on the Valiant began in earnest at the end of 1977 and progress began on manufacture from March 1978 through November that year and the initial turret was finished in September 1979.
A working prototype was being put through mechanical trials in June 1979, meaning it had taken less than 2 years to go from drawing board to the testing ground. Those automotive trials ended in September with some problems identified and the vehicle was returned to the factory for modifications in December. There, it was taken apart and thoroughly examined and the improvements started. Reassembled and improved, it was ready for unveiling to the British Army as a potential replacement for the aging Chieftain.
When the British Army received this tank in March 1980 at Bovington Camp in Dorset, it was faced with a tank unlike anything it had seen to that point. Gone was the highly sloped casting of the Chieftain to try and deflect incoming shells. Instead, this was replaced with a very rectangular turret made up of a series of flat faces, the defining characteristic of a tank made with Chobham technology and a general shape for which this new Western tank-generation would exploit.
Trials of this new tank began immediately to check for automotive performance and firing trials over their course. The formal public unveiling took place at the British Army Exhibition at Aldershot in June 1980 along with its formal new name ‘Valiant’. This new development was made possible by the formulation of an international sales consortium with Societe de Fabrication d’Instruments de Mesure (SFIM) (responsible for the panoramic stabilized commander’s sight), Vickers Instruments (gunners, telescopic, and unitary sights), Marconi Radar UK (gun stabilization and fire control), Philips and Odelft of Netherlands (panoramic stabilized thermal imager), and Simrad of Norway (laser range finders for the commander and gunner) each of whom invested financially in the project.
With these new partners, the redevelopment of the turret unveiled in 1980 was progressed and manufacture commenced at the Elswick, Works of Vickers, in 1981 followed by a demonstration of the finished product in the British Army Exhibition at Aldershot in 1982. British Army trials were completed by late 1982 after the tank had covered over 4,500 km of automotive and operator trials with few problems.
Still bearing ‘Trade Plates VRM 447 BB’, the Valiant, with turret reversed is put through its paces. The single periscope for the driver dates these images to 1982.
Following the 1982 unveiling, a promotional video was created at Long Valley, Aldershot, with the vehicle painted in a very-non-standard camouflage scheme for dramatic purposes. The goal was not to show some new style of camouflage, but simply to be noticed despite the non-military emulsion paints used and not to be confused with the Chieftain 900 project: an armor and mobility upgrade option offered for the old Chieftain.
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 stabilised panoramic (360 degree) sight. This sight had two magnification modes, x3, and x10 and incorporated a Nd-YAG-type laser rangefinder and had been added to the design in 1979 following a tour of the plant by Derek Rile and Patrick Michon of SFIM as part of their UK-wide sales tour. In addition to this was a PPE Condor-type 2-axis gyro-stabilised image intensifier (Phillips UA 9090 thermal sight) displayed on a 625-line television monitor for the gunner and commander alike.
The gunner had a x10 magnification Vickers Instruments L30 x10 telescopic laser sight with Barr and Stroud LF 11 Nd-YAG-type laser rangefinder fitted with a projected reticle image (PRI) for ranging. This was mounted coaxially with the main gun, directly on the rotor for the gun eliminating mechanical error. In addition to this, the gunner was provided with a Vickers Instruments GS10 periscopic sight for target acquisition mounted on the roof. The loader was provided with a single AFV No.10 Mk.1 observation periscope. The driver was well equipped with optical equipment too, including his own image intensifier, a PPE Badger Jenno viewer.
Through the clever use of electronics, the commander could access the imagery from both the gunner’s 2-axis gyro-stablised day-sight (and independently operate it), as well as the driver’s optics. Originally, the driver was provided with just a single wide-angle AFV No.44 Mark 2 modified periscope, but this was supplemented by the end of the 1982 trials with an additional periscope on each side of the original. The range of the night vision was limited to 1,200 m for the gunner and commander and 500 m for the driver.
Tracks and Suspension
The original tracks and running gear from the Vickers Mk. 3 were changed out in December 1979 for a wider track on which the Mk. 4 was running by March 1980. Running on six large rubber-tyred road wheels, similar to those on Chieftain, each wheel station was, however, attached to a trailing arm connected to a torsion bar. Additional secondary torsion bars were mounted inside the trailing arms for the arms of wheel stations 1, 2 and 6. During operation over particularly rough terrain, these secondary bars could be released to provide additional shock absorption. In addition to this, stations 1, 2, and 6 also had hydraulic shock absorbers. With the adoption of the Universal Turret for the 120 mm gun and the additional weight this brought about an improvement whereby all wheelstation-trailing arms were fitted with the secondary torsion bars. Later this type of suspension was changed to a hydrogas suspension system on a vehicle designated as Valiant 2.
The track, like that of the Mk.3, was a manganese steel single connector type. It was 558 mm wide, having replaced the original 520 mm wide track from the Vickers Mk. 3 and provided additional ground contact on which to spread the weight of the vehicle, reducing ground pressure to between 0.81 kg/cm2 and 0.83 kg/cm2. On its return run, the track was supported by 3 small rubber-tyred return rollers. Each side of the tank required 98 track links, each of which was fitted with a removable rubber pad to reduce road damage. Interestingly, Vickers’ own performance figures for the Valiant in its later form state a ground pressure of 0.92 kg/cm2 with a wider body (explained by the switch to wider side skirts with improved protection), a longer gun length (explained by the switch to a 120 mm gun), and a faster top speed (explained by the switch to the German MTU engine). All these modifications added weight and is the likely explanation as to why this ground pressure figure is higher.
The emphasis on the maneuverability of the Valiant was not to focus on top speed, but on acceleration. This meant an emphasis on the available torque from the engine. Trials were done using the derated Rolls Royce CV12TCA Condor diesel engine delivering 1,000 hp at 2,300 rpm to roughly match the very similarly sized General Motors 12V71T diesel engine delivering 915 hp at 2,500 rpm which was also tried. Ideally, the goal was the use of the Condor delivering its normal power output of 1,200 to 1,500 hp. There was sufficient space in the engine bay for engineers at Vickers to also contemplate the use of the German MTU 872 1,200 hp diesel engine. Operating with the RR Condor at 1,000 hp, the vehicle was capable of 51 km/h on the road with a range of 380 to 603 km depending on weight and engine from a fuel tank holding just 1,000 liters. Later figures state 1,150 liters. Vickers’ performance figures for the Valiant give the top speed as 70 km/h presumably quoting a top speed for the most powerful engine option.
The 17.41 liter RR Condor engine made at the Rolls Royce plant in Shrewsbury was a V12 (60 degrees) diesel engine with a 135 mm bore and a stroke of 152 mm with a low compression ratio and turbo-chargers. The V12-1200A, as used on the Valiant, weighed just 2,638 kg complete with water-filled radiators and coolant and rated at 1,000 hp was eventually selected to power the Challenger MBT, Chieftain 900, the Indian Vijayanta and even a re-engined Chieftain project.
The engine was matched to an automatic gearbox with mechanical speed gear as well as a centrifugal clutch as the TN12-1000 gearbox. The TN12-1000 was developed from the one used on the Chieftain and Mk. 3 providing gear-change efficiency improvements. The TN-12-1000 cross-drive transmission was produced by Self-Changing Gears Limited, Coventry, and weighed 1,361 kg, the same as the earlier TN-12 but was able to handle greater torque, specifically 3,660 Nm compared to 2,509 Nm of torque on the TN-12. The TN-12-1000 was also used in the Chieftain 900 and was able to manage engines up to around 1,200 gross hp.
This system provided 6 forward and 2 reverse gears. The important change was the elimination of the torque converter which reduced wasted torque from the power system, allowing for up to 150 hp of power available which would otherwise be wasted.
The vehicle was also fitted with an electrohydraulic differential which provided ease of steering and braking for the driver who, like on the Mk. 3, steered using a very simple yoke system instead of tiller bars. The steering, by means of handlebars, little different to a bicycle, used a twist-grip throttle control, a simple handle for the brakes, and a button which served as an override for the gearchange to prevent the gearbox from the automatic change down for improved performance for example during cornering or when firing on the move.
Underneath the square-cut appearance lay a tank similar to the Vickers Mk. 3. The regular armor of the Mk. 4 provided protection against small arms and cannon fire but was insufficient to protect against direct fire from Soviet tanks, unsurprisingly, as without the Chobham, it weighed just 30 tonnes. The primary way in which this weight was kept so low was the use of an all-welded all-aluminum alloy armor for the main structure of the hull. The type of alloy used was developed from 7039 series aluminum armor produced by Alcan Specialty and Aerospace Limited of Birmingham, England to produce a material more resistant to corrosion, ballistically stronger, and with better resistance to stress. Chobham technology had been made available to Vickers by the Ministry of Defence when it was announced in 1976 and two company directors from Vickers served on the Chobham Armour Committee, so they were well aware of its potential.
The turret, on the other hand, was primarily made from steel with the Chobham armor packs added across the front and sides. The adoption of aluminum for the hull differed from the Mk. 3, which had a conventional all-welded rolled armor steel hull. The turret itself followed on internally from the lessons of the Mk.3 using a cast steel front to produce a good ballistic shape which could not be matched in aluminum, and then with steel sections welded to the sides and rear in much the same fabrication manner as that used on Chieftain. It is not known, however, if when the turret was modified to take the universal mounting if this form of cast/weld steel was retained or if there was a switch to an all-welded steel plate turret underneath to simply manufacture.
With the addition of the Chobham armor, the appearance was changed, as was the weight, an additional 16.3 tonnes, with the likelihood that in the future, as armor technology improved, more weight could be added. Across the frontal 60-degree arc (30 degrees from centerline each direction), the Valiant, with this new armor, offered ballistic protection above that of the then in-service 56-tonne Chieftain, a design which had started in the 1950s.
An important additional consideration for the tank was the ‘future battlefield’ of the 1980s and 1990s seeing a potential large-scale use of nuclear or chemical weapons. Crew protection, therefore, was supplemented by a built-in nuclear, biological, and chemical warfare air filtration system made by Westair Dynamics and located on the back of the turret. This NBC filter system was mounted externally which made 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.
Inside the vehicle was the Graviner Firewire CO2-based automatic fire fighting system, although these CO2 cylinders could be switched for an alternative gas like Halon if required.
The turret design itself had the same diameter ring as that of the Chieftain and was supported on a ball race with a semi-type basket. The turret crew were situated on a turntable that rotated with the turret.
The Valiant, using a clever design, was able to offer a choice of guns with either the tried and trusted Royal Ordnance L7A3 105 mm rifled gun or, in a new mounting in the Universal Turret, with the L11 120 mm rifled gun. In order to potentially fulfill the NATO need for a common 120 mm smoothbore gun, the Rheinmetall 120 mm gun could also be fitted, a gun finishing development for use in the M1E1 and Leopard 2 at the time. When it first appeared, the Valiant mounted the 105 mm gun, but this was quickly exchanged for the superior L11A5 120 mm rifle instead. The advantage of the Universal Turret mounting being that the main gun could be removed in one piece from the front of the turret through the trunnions without having to remove the turret. This was achieved by using a wide-diameter gun rotor with pre-loaded trunnion bearings and extended cradle bearings. Not only did this allow for different guns to be mounted easily but also for good stability and thereby accuracy from the gun.
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 information into the computer system and the barrel was clad in a rigid thermal sleeve (a patented Vickers design) made from a material called Fibrelam Vickers developed with Ciba-Geigy of Duxford. This sleeve reduced distortion and was used on the Valiant, the Mk. 7 vehicle and even had a 105 mm gun version for the Mk. 3. That sleeve was thoroughly tested at Fort Halstead by the Royal Armament Research and Development Establishment (R.A.R.D.E.) and found to offer a significant improvement in reducing barrel sag in hot weather.
The fire control and gun stabilization system was an all-electric system developed by Marconi. This 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 Centaur 1 fire control system (FCS) was a state of the art solid-state system designed specifically for Valiant which completely integrated all of the different sightings and optics. The gun itself had a 2-axis gyro-stabilized mounting located underneath the breach and with the Centaur 1 FCS the gun could be directly slaved to either the commander’s gyro-stabilized day or thermal sights. Further, these balancing systems interfaced with the 3 primary sighting systems: the gunner’s telescopic laser sight, the commander’s gyro-stabilized panoramic laser sight, and the thermal imaging system. The ballistic computer took range data from the laser range-finders, manual values, and tracking data (for a moving target) and calculated a firing solution with supporting data from a tilt-sensor measuring the tilt-axis on the trunnion, with manually entered data such as ammunition type, barrel wear, and charge temperature. The Centaur system then superimposed a mark over the gunner’s sight graticule and tracked the target with the pressing by the gunner of the laser button. The gun was then ready to fire within 3 seconds of the tracking starting.
The elevation range for the 105 mm L7 gun was -10 to +20 degrees and it was capable of firing all commonly available 105 mm rounds. Storage was provided for up to 56 rounds of 105 mm, 44 rounds for the 120 mm Rheinmetall smoothbore, or 52 rounds for the L11A5. Rounds could be carried in the turret, in the basket as ready rack ammo and in a space alongside the driver as well.
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.
Secondary armament included a single 7.62 mm machine Hughes chain 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.
Firing trials at Lulworth took place at the end of 1982 against simulated targets using APDS at 1,500 m range and found to be excellent. By early 1983, the vehicle, refitted with the Universal Turret mount, was showing off the 120 mm L11A5 to potential Middle Eastern customers. Marketing literature from Vickers at the time sub-divided the configurations for potential buyers as Configuration 1 with the 105 mm L7A1, 60 rounds, of APDS or HESH, Configuration 2 with the 120 mm L11A5 with 44 rounds (different from the earlier plan for 52) of APDS or HESH, or Configuration 3 with the Rheinmetall 120 mm smoothbore with 44 rounds of APDS and HESH (MP).
Other than the British Army there was other interest in the Valiant, specifically in the Middle East but also from some European nations including Spain who at the time were seeking a new tank. Vickers may have hoped for some success here as, after all, they had already sold a number of their Mk.3 tanks to Kuwait in the 1970s. In order to try and gain interest, the Valiant was packed up and shipped out to Doha, Qatar, a 3-month trip. This tour involved showing off the Valiant to Qatar, Jordan, Abu Dhabi (United Arab Emirates), and finally Egypt. The Valiant did its tour of prospective users offering these nations a tank objectively better in many ways than certainly the British Challenger. Sent with British Army crews, the Valiant, Challenger 1, and Stormer painted in desert colors performed a variety of trials whilst the team from Vickers traveled separately to talk about the technology. On one occasion, in Bahrain, there was a ‘mishap’ where the Vickers team got lost on the way to the firing trials and accidentally found itself driving past the targets on the firing range, something on which to focus the mind.
Despite these trials, there were no orders from this tour, and other than the sale of a single gold-plated Sterling SMG, was unsuccessful, although it had led to an invitation to participate in desert trials in the United Arab Emirates in July and August 1983.
Those trials in the UAE were to involve comparisons of the British Challenger 1, the French AMX-40, and the Vickers Valiant. Here, the lighter weight and automotive power of the Valiant was impressive leaving the other two contenders behind. During an off-road trial, however, the Valiant suffered a small disaster. A drain plug in the final drive had come out. This led to sand getting into the unit as well as a loss of lubricant and causing the unit to fail.
A new one had to be flown out from the UK delaying Valiant for two days but it was back operational to take part in firing trials where once more it outperformed the other two vehicles. It was not the only one of the three to suffer mechanical problems. The AMX-40 suffered a severe set of problems with the automotive system and was out of use for over a week. In fact, the only one without major problems was the Challenger 1. The UAE, however, bought the Leclerc instead.
The Fall of the Valiant
The Valiant had been a strong performer. Automotively powerful albeit it still a little underpowered but with a world-beating fire control system. The British had gone with the Challenger 1 MBT and there were no orders for the Valiant. The Valiant 2 was to improve on the Valiant with planned automotive improvements in the engine and suspension but whilst at Larkhill, the Valiant slipped off the low loader during transport and rolled into its roof. The optics were damaged but repairable, the hull was twisted and had to be scrapped. The Valiant was dead and all that could be salvaged was the significant investment in the turret. With no hull on which to make a Valiant 2 and with a large sum of money invested in a failed project, Vickers was in trouble. A review of automotive options for a new chassis were considered and would eventually lead to the attempt to use the Leopard 2 which created a whole new tank: the Vickers Mk.7/2.
Had the Valiant received orders, Vickers was planning a series of variants, specifically a bridge layer, an armored recovery vehicle (ARV) version and a self-propelled gun. Options also all available for the Vickers Mk.3.
The ARV was to be fitted with a 30-tonne direct-line pull capstan winch capable of up to 75-tonne of pulling by multi-reeving of the rope. A hydraulic crane was also available with an auxiliary 3-tonne winch.
The 13.4 metre long bridge laying version was to carry a class 60 bridge. The self-propelled gun variant was simply designed to take the universal 155 mm howitzer turret developed by Vickers Shipbuilding and Engineering. None of those three vehicles were ever built, however.
The Valiant, despite its good features, was not a success. It received no orders despite a lot of interest from the British and even being shortlisted by the Spanish in 1985, but Vickers would not give up. The turret was the biggest selling point, as a Universal Turret was able to offer a wide range of firepower and optical options. The turret would live on and was modified once more. It would go on to be tested on the Leopard 2 hull to create the Vickers Mk.7/2, having a maneuverability boost from its MTU engine. That vehicle would fail too, but the lessons learned would eventually lead to the turret contract for Brazil for their EE-01 Osorio.
Vickers Mk.4 Valiant Specifications
29.53 m long (with 105 mm gun)
10.62 m long (with 120 mm gun)
8.47 m (gun to the rear)
3.3 m wide (with side skirts)
3.6 m with improved skirts
RO L7A3 105 mm rifle or L11A5 120 mm rifled main gun
or Rheinmetall 120 mm smoothbore
coaxial 7.62 mm or 12.7 mm machine gun
roof-mounted remote-control 7.62 mm or 12.7 mm machine gun
4 (driver, gunner, loader, commander)
Rolls Royce CV12TCA Condor diesel engine 1,000 hp at 2,300 rpm or normally rated for 1,200 hp. Possible to uprate to 1,500 hp.
General Motors 12V71T diesel engine delivering 900 hp at 500 rpm.
German MTU 872 1,200 hp diesel engine
51 to 61 km/h (road) depending on engine (Vickers state 70 km/h)
All aluminium alloy hull with Chobham across front 60 degrees. All steel turret with Chobham armor across front and sides.
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.
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.
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.
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’.
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.
United Kingdom (1950-57)
Heavy SP Anti-Tank Gun – One Stage 1, Two Stage 2s Built
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.
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.
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”.
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.
Specifications (Stage 2)
7.82 (without gun) x 3.39 x 3.6 m
(25’7″ x 11’1″ x 11’8”)
5 (driver, gunner, commander, x2 loaders)
Rolls-Royce Meteor; 5-speed Merrit-Brown Z51R Mk. F gearbox 650 hp (480 kW), later BL 60, 695 bhp
United Kingdom (1950-1957)
Heavy Gun Tank – 1 Mock-Up & Various Components Built
Viewing the public debut of the Soviet Union’s IS-3 heavy tank at the Berlin Victory Parade of September 1945, the Western powers – including Great Britain – were shocked. As heads of the British, American, and French Armies watched these machines clatter down the Charlottenburger Chaussee, they saw the shape of a new generation of heavy tanks. From the exterior, the IS-3 was a tank with well-sloped and – apparently – heavy armor, a piked nose, wide tracks, and a gun at least 120 mm in caliber. At least in appearance, this was superior to anything being fielded by the other victorious Allied powers at the time.
The respective officials knew that they had nothing in their arsenal capable of potentially combatting this menacing tank that was now in service with an increasingly aggressive USSR. In response, the militaries of these countries began to develop heavy tanks that – they hoped – would be able to combat the IS-3. The United States would develop the M103 heavy tank, while the French experimented with the AMX-50. Britain went in a different doctrinal direction and created a ‘Heavy Gun Tank’. This was a uniquely British designation that was not governed by weight, but the size of the gun. This vehicle was based on the experimental FV200 ‘Universal Tank’ chassis and given the official and somewhat long-winded title of ‘Tank, Heavy No. 1, 120 mm Gun, FV214’. This vehicle would be better known as the ‘Conqueror’.
Weighing in at 65 long tons* (66 tonnes) with armor up to 13.3 in (340 mm) thick, the Conqueror was one of the largest and heaviest tanks Britain would ever field. Like the M103 and AMX-50, the Conqueror was armed with a powerful 120 mm Gun, specifically the ‘Ordnance, Quick-Firing, 120mm, Tank, L1 Gun’. This gun could punch through an impressive 17.3 inches (446 mm) at 1,000 yards (914 meters) firing Armor Piercing Discarding Sabot (APDS) ammunition. This was more than enough to combat the IS-3 but, at the time, this was unknown to the British War Office (WO). As such, even greater firepower was investigated.
What followed was the FV215. With its monstrous, 183 mm gun, this vehicle has become something of a legend among enthusiasts of a particular age, largely due to a popular video game. Unfortunately, this has meant a number of falsehoods have been spread about the vehicle. This article will highlight the truth behind this uniquely British vehicle.
*As this is a British vehicle, mass will be measured in ‘Long Ton’ otherwise known as the ‘Imperial ton’. It will be shortened to ‘ton’ for ease with a metric conversion alongside.
In the aftermath of the Second World War, the War Office reviewed the future of the British Army’s tank arm. In 1946, it did away with the ‘A’ designator used on tanks such as the Churchill (A.22) and Comet (A.34). The ‘A’ number was replaced by the ‘Fighting Vehicle’ or ‘FV’ number. In an attempt to streamline the tank force and cover all the bases, it was decided that the military needed three main families of vehicles: the FV100, the FV200, and FV300 series. The FV100s would be the heaviest, the FV200s would be slightly lighter, and the FV300s would be the lightest. It should be noted that the rest of the FV series 400, 500 etcetera were not in weight order although these first 3 serials were. All three projects were almost canceled due to the complexity that would have been involved in producing the respective series. In the end, both the FV100 and FV300 series were canceled. The FV200 hung on in its development, however, as it was projected that it would eventually replace the FV4007 Centurion.
The FV200 series included designs for vehicles that would fill various roles ranging from a gun tank to engineering vehicles and Self-Propelled Guns (SPGs). It was not until later years that the other uses of the FV200 chassis were explored, such as with the FV219 and FV222 Armoured Recovery Vehicles (ARVs). The first of the FV200 series was the FV201, a gun tank that started development in 1944 as the ‘A45’. This tank weighed around 55 tons (49 tonnes). At least two or three FV201s were built for testing, but the project went no further than that. Work on the project ceased in 1949.
As the ‘Heavy No. 2’ part of its designation implies, the FV215 was intended to be a follow up to the FV214 Conqueror – ‘Heavy No. 1’. The vehicle was also known as the ‘FV215, Heavy Anti-Tank Gun, SP’ (SP: Self Propelled). The project started life in mid-1949, and was aimed at increasing the firepower of the ‘Heavy Gun Tanks’. 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 (1,828 meters), a feat impossible even for the powerful 120 mm L1 gun of the FV214. By 1950, Major General Stuart B. Rawlins, Director General of Artillery (D.G. of A.) had concluded that there was no such gun available with that level of ballistic performance. 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 was of the non-doctrinal opinion that a ‘kill’ did not necessarily mean the complete destruction of an enemy vehicle. For example, a blown-off track was also 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 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’. The 183 mm L4 became one of the largest and most powerful tank guns in the world. With the gun developed, the rest of the vehicle had to be designed around it. It is estimated that the vehicle would have cost between £sd44,400 and £sd59,200 (£1,385,662 – £1,847,549 in today’s Pounds) per unit.
The FV215 in Detail
Based on the Conqueror adaption of the FV200 chassis, the hull of the FV215 would have shared some similarities. For example, the hull would have been 25 feet (7.62 meters) long. It would have been slightly narrower than the FV214 at 12 feet (3.6 meters) compared to 13.1 feet (3.99 meters). With a planned height of 10.6 feet (3.2 meters), the FV215 would have been slightly shorter than the FV214. Unladen, the vehicle would weigh 61 tons (62 tonnes) while being in ‘battle order’ – i.e. fully equipped – would have seen the weight climb to 65 tons (66 tonnes).
The FV215 would have been operated by a 5-man crew consisting of the commander (turret left), the gunner (turret front right), two loaders (turret rear), and the driver (hull front right).
While the basic chassis and running gear remained the same as the FV214, the layout of the rest of the vehicle was completely changed. Three turret layouts were considered – front, middle, and rear. A rear-mounted turret was chosen as was considered more advantageous to balance. The power plant was also moved to the center of the vehicle.
The driver remained at the front right of the hull. Like on the Conqueror Mk. 2, he had a single periscope – in this case, a No. 16 Mk. 1 periscope with a 110° field-of-view – mounted at the top of the upper-glacis plate for vision. He would have had a large hatch above his head that would pop up and swing to the right. As with the FV214, two traditional tiller bars would have been used to operate the vehicle. Also, the driver’s seat could be placed at various heights and positions, allowing the driver to operate head-out or under the protection of a closed hatch. Extensions atop the tiller bars would allow easy operation when driving head out.
The glacis is listed as being a 4.9 inch (125 mm) thick steel plate, sloped at 59 degrees. Side armor was to be 1 ¾ inch (44 mm) thick plus the 6 mm thick ‘bazooka plates’ added over the running gear. The floor would have been 0.7 inches (20 mm) thick, with an extra 0.6 inch (16 mm) ‘mine plate’ installed below the driver’s position. The roof of the hull would have been 1 ¼ inches (32 mm) thick.
Mounted at the rear of the hull, the new turret was large and boxy. Unlike the Conqueror’s cast turret, the FV215’s turret was to be of welded construction. Existing dimensions list the turret as 12 feet (3.6 meters) wide sitting on a 95 inch (2.4 meter) diameter turret ring. Overall, the turret would have weighed 20 tons (20.3 tonnes). Unfortunately, the exact thickness of the turret armor is unknown as records list the turret face only as “will protect from a 100 mm gun in a 30-degree arc”. The rear of the turret and the roof would have been 0.6 inches (17 mm) thick.
A feature carried over from the Conqueror was the rangefinder. On the FV215, this would have been used by the gunner, not the commander as with the FV214. This was placed laterally across the front of the turret roof, and was made by the York-based company of Cook, Throughton & Simms. The rangefinder had a 6 foot (1.8 meter) sight-base and used the ‘coincidence’ method of ranging. This method consists of laying two images on top of each other. When the two images completely overlap, the range measurement is taken. This information is then used by the gunner to accurately range the gun.
The commander – located on the left of the turret – would have been equipped with a large rotating cupola designated the ‘Cupola, Vision, No. 5’ mounting a ‘Sight, Periscope, AFV, No. 11’ along with a ‘Periscope, Tank No. 20’ and ‘No. 21’ providing an uninterrupted view of 140 degrees. A collimator was also provided that would display the view of the gunner’s main sight.
Two smoke dischargers, presumably the ‘Discharger, Smoke Grenade, No. 1 Mk. 1’ as on the Conqueror, would have been placed on the sides of the turret. Each launcher featured 2 banks of 3 tubes and were fired electrically from inside the tank. Atop the roof, on the hatch for the two loaders, was an air-defense mounting point for a machine gun. This was set to be a .50 Cal (12.7 mm) Browning M2 heavy machine gun – known simply as the .5 Browning in British service. This was an uncommon choice for British vehicles of this era. The machine gun could elevate to +70 degrees and depress 5 degrees. Four boxes totaling 950 rounds were carried for the .50 Cal.
The ‘Ordnance, Quick-Firing, 183mm, Tank, L4 Gun’ was one of the only parts of the FV215 that was built and tested. A small number of the guns were built, but it is unclear just how many. Records suggest at least 12 were built. In an effort to get it into service before the development of the FV215 had finished, the W.O. explored the idea of mounting it on the Centurion chassis. This resulted in the development of the experimental FV4005, a vehicle that would have been rushed into production should the Cold War have turned hot. A similar connection can be found with the Conqueror and the FV4004 Conway. Unfortunately, the exact length of the 183 mm gun is currently unknown to the author, 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) while its mount weighed 7.35 tons (7.4 tonnes). Although the turret was capable of full 360-degree traverse, firing was physically limited to a 90-degree arc – 45 degrees over the left and right of the vehicle. It could also fire directly to the rear. A safety lockout prevented the gun from firing over the ‘broadside’ position. The gun would have a vertical traverse range of +15 to -7 degrees, however, it is unclear whether – as with Conqueror – it would have been fitted with a limiter that halted it at -5 degrees.
The gunner sat on the left of the gun, in front of the commander. This was unusual for British tanks as it was more common for the gunner to be located on the right of the gun. He had hand controls for elevation and traverse, both of which were electrically powered. Duplicate controls were also available to the commander, but only the gunner was equipped with manual backups. The elevation controller also featured triggers for the main gun and coaxial machine gun. The gunner would aim the main armament via the ‘Sight, Periscope, AFV, No. 14 Mk. 1’.
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 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 approx half the 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 2 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.
This oversized ordnance is the reason the vehicle would be manned by two loaders. Between them, they could achieve a rate of 2 to 2 ½ rounds per minute. Also, due to its size, ammunition stowage was limited to just 20 rounds. Twelve of these would have been ‘ready-rounds’ stowed in the turret against the interior of the walls.
The size and power of the gun were also why the rear-turret design was chosen for the FV215. Because of its – estimated – 15 foot length, the gun would overhang the front of the vehicle considerably should it have been placed in a centrally mounted turret. This could lead to the gun being buried in the ground when approaching or descending steep inclines, fouling the barrel. Having the gun at the rear also made the vehicle a more stable firing platform as the front half of the vehicle acts as a counterweight to the recoil force, preventing the vehicle from tipping too far backward.
As well as the roof-mounted machine gun, secondary armament consisted of a coaxial L3A1 .30 cal (7.62 mm) machine gun – the British designation of the US Browning M1919A4. This was not coaxial in the traditional sense, as it was not integral to the main gun mount. Rather, the machine gun was placed in a blister, cast into the roof with the range-finder and located on the top-right corner of the turret. The L3A1 had the same vertical traverse range as the main gun at +15 to -5 degrees. Six boxes totaling 6,000 rounds were carried for the ‘coaxial’ machine gun.
While the Conqueror was equipped with the Rolls-Royce Meteor M120 petrol engine, it was planned that the FV215 would use the Rover M120 No. 2 Mk. 1. This 12-cylinder, water-cooled petrol engine produced 810 horsepower at 2,800 rpm. This would have propelled the vehicle to a top speed of 19.8 mph (32 km/h). A Merritt-Brown Z5R gearbox would also be installed, providing 5 forward gears and 2 reverse. Due to the turret being relocated to the rear of the vehicle, the power plant was placed centrally in the hull, separating the driver’s compartment from the fighting compartment. The engine was also placed 6 inches (15 cm) off the centerline, but whether this was to the left or right is unknown. The exhaust pipes would emerge from the sides of the hull roof, just in front of the turret and terminate in large trumpet-like tubes. The reason for these are unknown. The Rover engine would be fed by 250 UK gallons (1,137 liters) of fuel. As with the Conqueror, a small, auxiliary 4-cylinder petrol engine was provided to drive a generator that would supply the vehicle with electrical power, with or without the main engine running.
Like the FV201, Centurion and Conqueror before it, the FV215 was set to utilize a Horstmann suspension system with 2 wheels per-bogie unit. The wheels were made of steel, measuring approximately 20 inches (50 cm) in diameter, and constructed from 3 separate parts. These consisted of an outer and inner half, with a steel rim in contact with the track. Between each layer was a rubber ring. The idea behind this was that it would be more efficient on the rubber and would not need to be replaced as often. The Horstmann system consisted of three horizontal springs mounted concentrically, guided by an internal rod and tube. This allowed each wheel to rise and fall independently, although the system did struggle if both wheels rose at the same time. Four bogies lined each side of the hull of the vehicle, giving it 8 road-wheels per side. There were also 4 return rollers, 1 per bogie. The advantage of using bogies lies in maintenance and crew comfort. Having externally mounted bogies means there is more room inside the tank and also, should the unit become damaged, it is relatively easy to remove it and replace it with a new unit.
Despite the engine being repositioned, the drive sprockets remained at the rear of the running gear, with the idler wheel at the front. Going by the pre-production imagery, it would appear the spoked idler of the FV214 was replaced with a solid wheel. The track was 31 inches (78.7 cm) wide and had 102 links per side when new. The suspension gave the vehicle a ground clearance of 20 inches (51 cm), and the ability to climb a 35 inch (91 cm) vertical object. It allowed the tank to cross trenches up to 11 feet (3.3 m) wide, negotiate gradients up to 35 degrees, and ford water obstacles up to 4.5 feet (1.4 m) deep without preparation. The vehicle had a turning circle of 15 – 140 feet (4.8 – 42.7 m respectively) depending on gear selection. It could also pivot or ‘neutral’ steer on the spot with each track turning in opposite directions.
So Close, Yet So Far
In 1951, the company of Vickers had filed a report on the concept of the FV215 and, by June 1954, a contract had been signed for the production of a prototype vehicle known as ‘P1’ (Prototype No.1). In October that year, it was also clear that the AA mount for the .50 cal machine gun would not be ready, and as such an L3A1 was substituted. In March 1955, the same year the FV214 entered service, the order had increased to include two pre-production vehicles. A full-scale mock-up – including interior components and a faux engine – was completed between July 1955 and January 1957, with 80% of accompanying schematics also produced. Work started on P1 in September 1955 with a selection of spare parts. The two pre-production vehicles were canceled in early 1956, but work went ahead on P1 which was set to be completed at some point in 1957. Troop trials would then take place by the end of that year. This, however, is where the FV215 story ends.
In 1957, with just the gun, a couple of turret faces, and a number of other smaller parts built, the FV215 project was officially canceled. This decision was largely down to the Army. From the outset, the Army was not keen on the concept of the vehicle, mostly due to the fact that large-caliber weapons provide a number of logistical issues, mostly caused by the sheer dimension of the weapons. One only has to look at the Conqueror and the issues its size presented to operators during its time in service to understand this hostility to the FV215. At the same time, there was a new contender in the race to find an opponent for the USSR’s heavy armor. Of course, by the mid-1960s, the FV215’s intended opponent, the IS-3, would prove to be a far less threatening tank than the Allies had imagined roughly 12 years prior in 1945.
The new contender was the FV4010, a heavily modified, turretless vehicle built on the Centurion chassis and armed with the newly developed Malkara Anti-Tank Guided Missile (ATGM). This vehicle offered the same damage potential as the 183 mm gun, but in a lighter vehicle and with better accuracy at long ranges. Even though this vehicle also went through full-scale development, it too would not see production or service. The Malkara missile, however, was accepted for service.
Had the FV215 entered service, it would have filled the role much the same as the Conqueror. Its role on the battlefield would have been to support other friendly troops, rather than strike out on its own. It was designed to destroy enemy tanks from afar, covering the advance of the lighter tanks such as FV4007 Centurion. In offensive operations, the FV215 would be placed in overwatch positions and fire over the heads of the main force as it advanced. In defensive operations, the vehicle would again take an overwatch role, but this time from key, pre-set strategic positions to meet an advancing enemy.
Busting a Myth: FV215A & B
Over the years, a couple of erroneous designations have emerged concerning this vehicle. These are the ‘FV215A’ and ‘FV215B’. The ‘FV215A’ is the false designation, probably mistaken for the planned AVRE (Armoured Vehicle Royal Engineers) vehicles of the FV200 series. The FV215B is simply a fictional designation for the FV215 Heavy Gun Tank.
Had it entered service, there is no doubt that the FV215 would have been one of the most deadly gun-tanks to have ever existed. At the same time, it is not hard to see why it was not accepted for service. The Conqueror on the other hand, would end up staying in service for 11 years, finally being retired in 1966. It was Great Britain’s first and last ‘Heavy Gun Tank’.
The logistical and high-cost nightmare of the Conqueror would have only continued with the more heavily armed FV215. Heavy vehicles are expensive, not only to build, but to maintain. The heavier a vehicle, the harder the wear and tear on parts, so parts have to be replaced more often increasing maintenance time and burden and so on.
On top of this there was another issue: the feared Soviet heavy tanks like the IS-3 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 the Conqueror and FV215 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 the improved anti-armor performance of smaller guns and by the appearance of a new generation of accurate Anti-Tank Guided Missiles (ATGM).
It is perhaps ironic that the Soviet tank which perhaps started this fear, the IS-3, was itself found to be seriously wanting in combat. Losses during the invasion of Prague to little more than lightly armed civilians showed serious tactical failings in the way in which tanks were handled along with the utter disaster of their use in the 1967 Six-Day War with Israel. Here, Egyptian IS-3s were lost in large numbers to mechanical failures and to ‘inferior’ lighter tanks like the British-supplied Centurion and American-supplied M48. The paper-tiger had had its day and the IS-3-smashing Heavy Gun Tanks were as obsolete as the tanks they were designed to counter.
An article by Mark Nash, assisted by David Lister, Andrew Hills & Ed Francis.
Illustration of ‘Tank, Heavy No. 2, 183mm Gun, FV215’. The representation of a 6 ft (1.83 m) gives some idea of the scale of the vehicle and its 183 mm L4 gun. The vehicle is represented in the standard British Army green. As the vehicle never entered service, some of the smaller details – such as the wire reel and lifting eyes – are speculative. This illustration was produced by Brian Gaydos, based on work by David Bocquelet, and funded by our Patreon campaign.
25 feet x 12 feet x 10.6 feet (7.62 x 3.6 x 3.2 meters)
61 – 65 long tons (62 – 66 tonnes)
5 (Driver, commander, gunner, 2 loaders)
Rover M120 No. 2 Mk. 1, 12-cylinder, water-cooled, 810 hp
19.8 mph (32 km/h)
Ordnance Quick-Firing (QF) 183 mm Tank L4 Gun (20 rounds)
Sec. 1 – 2 L3A1 (Browning M1919A4) .30 Cal (7.62mm) Machine Gun (6000 rounds)
.5 Browning (Browning M2) .50 Cal (12.7 mm) heavy machine gun (950 rounds)
Front (Upper Glacis): 4.9 inch (125 mm) @ 59 degrees
Sides: 1 ¾ in (44 mm) + 0.2 in (6 mm) ‘Bazooka Plates’
Roof: 1 ¼ in (32 mm)
Floor: 0.7 in (20 mm) + 0.6 in (16 mm) ‘Mine Plate’
Face: “protection from a 100 mm gun in a 30-degree arc”
Rear: 0.6 in (17 mm)
Roof: 0.6 in (17 mm)
In 1954, the British, of C. A. Parsons Ltd. made history. At a public display of armored vehicles, they unveiled an odd-looking, silver turretless tank hull. This vehicle was a world first. Inside the engine bay was a new, experimental turbine engine.
The vehicle was a testbed, serving to illustrate the future possibility of mounting a turbine engine in an armored vehicle. Other countries, notably Nazi Germany in the Second World War, had considered turbine technology in a tank, but it was this British tank which was to make history as the first armored vehicle in the world to be propelled by a turbine engine. However, despite proving that the technology worked, the project ended without adoption by the British Army and it was not until a generation later, with the appearance of the Swedish Strv 103 ‘S-Tank’ and the later American M1 Abrams or Soviet T-80, that this engine type would be seen in a production vehicle.
In the aftermath of the Second World War, the War Office (W.O.) reviewed the future of the British Army’s tank arm. In 1946, it did away with the ‘A’ designator used on tanks such as the Churchill (A.22) and Comet (A.34). The ‘A’ number was replaced by the ‘Fighting Vehicle’ or ‘FV’ number. In an attempt to streamline the tank force and cover all the bases, it was decided that the military needed three main families of vehicles: the FV100, FV200, and FV300 series. The FV100s would be the heaviest, the FV200s would be slightly lighter, and the FV300s would be lightest. While the FV100 and 300 series were canceled, the FV200 hung on in its development, as it was projected that it would eventually replace the Centurion.
The FV200 series included designs for vehicles that would fill various roles ranging from a gun tank to an engineering vehicle and Self-Propelled Guns (SPGs). It was not until later years that the other uses of the FV200 chassis were explored, such as with the FV219 and FV222 Armoured Recovery Vehicles (ARVs). The first of the FV200 series was the FV201, a gun tank that started development in 1944 as the ‘A.45’. The most well-known member of the FV200 family is the FV214 Conqueror Heavy Gun Tank.
Armored fighting vehicle design is commonly conceived as revolving around a pyramid of factors: firepower, armor, and mobility. An AFV can rely on two of these, but not all three. For instance, a heavily armed and armored tank will sacrifice mobility, a fast tank will sacrifice armor, and so on. The idea behind installing a turbine engine into an armored vehicle was to overcome this ‘pyramid’. If an engine could be developed that would provide the same performance yet weigh less, then thicker armor and a more powerful gun could be carried.
The idea of using a turbine engine in an AFV was championed by none other than the father of British jet aircraft, Sir Frank Whittle. While aircraft powered by engines of his design – the Gloster Meteor – were engaging V1 rockets by the end of WW2, he was not the first to develop the jet engine.
Even before the Second World War, Nazi Germany was experimenting with jet propulsion. By War’s end, Germany had become the first nation to actively employ jet-powered aircraft in combat, namely in the form of the Messerschmitt Me 262. The end of the War brought the British capture of equipment, documents, and German scientists. With them came insight into some of the AFV plans the Germans were hoping to employ in the later years of the War. One of these plans was for a turbine-engine powered Panzer variant. This project reportedly even had the backing of the Waffen SS.
In late-1948, the Power Plant branch of the Fighting Vehicle Research And Development Establishment (F.V.R.D.E.), based in Chertsey, filed a report on this German AFV turbine project. This lead to a project to investigate the possibility of developing a turbine engine for use in future British tanks and armored vehicles. To this end, in January 1949, a contract was signed with C. A. Parsons Ltd. of Newcastle upon Tyne for the development of this new turbine engine. It was outlined that the engine was to be capable of developing 1,000 hp at 15℃ (60℉), or 900hp at 43℃ (110℉). Although various types of turbine were in development at this time, Parsons opted for a simple, cycle-based engine with a centrifugal compressor driven by a single-stage turbine, in conjunction with a two-stage ‘work’ turbine.
The Turbine Engine
Turbine engines consist of four main components; the compressor, combustion chamber, the turbine, and the heat exchanger. Simply explained, they all work in conjunction thusly:
The compressor serves to compress airflow, in-turn raising the temperature before the fuel injection. The combustion chamber’s role is to provide a continuous flow of fuel into the turbine while keeping it at a constant temperature.
Quite obviously, the turbine is the heart of this engine type. A turbine is simply a propeller propelled by the force hitting it; in the case of this engine that would be hot, vapourised fuel. The main turbine drove the compressor while a separate ‘work’ turbine would transfer the rotary propulsion directly to the gearbox.
The heat exchanger increased the temperature of air before it entered the combustion chamber, reducing the amount of fuel that was consumed bringing the air up to the required temperature. Unlike regular combustion engines where overheating is detrimental to performance, the opposite is true for turbines. The hotter it runs, the greater the power output.
C. A. Parsons Limited. Btd., based in Newcastle upon Tyne, England, was founded in 1889 by Charles Algernon Parsons and quickly established itself as a leading manufacturer of steam turbine equipment on land and for naval use. This work continued into the development of the turbine engine envisioned by the Power Plant branch of the FVRDE. To assist with the project, 5 German scientists from the late WW2 project were assigned to the developmental team.
Unfortunately, one of the benefits of the turbine engine could not be met by Parsons: the weight. It was found that, at the time, only be using thinner gauge materials and inferior lighter alloys could the engine be brought to a weight equal to a standard engine. At the time, a standard engine was projected to weigh around 4,100 lb (1,860 kg), while the turbine weighed in at 5,400 lb (2,450 kg).
The final design of Parsons’ Turbine received the model number ‘No. 2979’. It featured a single-stage centrifugal compressor, driven by an axial flow turbine. Only the turbine disc was air-cooled. The smaller ‘work’ turbine was of the two-stage axial flow type, which ran in conjunction with the compressor. A reduction gear unit was fitted to reduce the work-turbines revolutions-per-minute from 9,960 rpm to 2,800 rpm. Lucas Ind., a Birmingham-based company, provided a fuel pump and an air-fuel ratio control unit with an integral throttle unit. To prevent the work turbine from over-speeding during gear changes, it could be mechanically connected to the compressor turbine. This also provided engine-braking. When starting, the compressor turbine was rotated via a 24-volt starter motor and the fuel ignited by a torch-igniter. The rest of the starter sequence was automatic, commencing with the press of the starter button on a new dashboard which was made by the Austrian company Rotax.
For trials, it was decided that the engine would be placed in the hull of a vehicle from the FV200 series, Prototype ‘P7’ (No. 07 BA 70) of the FV214 Conqueror trials to be exact. The hull was one of three FV221 Caernarvon hulls built at Royal Ordnance Factory, Leeds.
The engine bay was modified with a new support structure to hold the turbine engine. A standard five-speed gearbox was introduced with Merritt-Brown steering. The gearbox compartment of the hull had to be lengthened to accept the new gearbox. What was the fighting compartment was completely gutted to make way for a cyclone air-cleaner unit, consisting of 192 cyclone units mounted in 8 24-unit banks. Two new fuel tanks were also introduced into the fighting compartment, along with a homelite generator. This was required as the turbine lacked a generator drive. The driver’s compartment – which remained at the front right of the bow – was largely unaltered, apart from the addition of a new instrument panel with 29 separate dials, gauges, and instruments which were all crucial to monitor the engine.
The new engine and cyclone air-filter also necessitated some external modification. A large circular plate was placed over the fighting compartment/air-filter bay with a large vent in the roof. The engine deck saw the heaviest modifications. The old deck, which was covered in hinged louvers, was replaced with 3 flat panels that were bolted down. The left and right panel featured 3 small vents, while the central featured one large vent. A taller section with two vents was built up at the rear of the engine deck to provide extra room. The rear plate also saw the addition of a large ventilation ‘box’, through which exhaust gasses and excess heat would escape.
Most other features of the hull remained identical. The Horstmann suspension, tracks, fenders, and fire extinguisher system were all standard to the FV200 series of vehicles. A small addition to both the left and right fender was a folding ladder placed over the idler and sprocket wheels. This allowed the test crew to easily scale the vehicle. An unexplained feature of the test vehicle was the second hatch placed next to the driver. This hatch was without a door, and it is unclear whether it was an original feature of P7 or introduced for the tests. Altogether, the vehicle weighed about 45 long tons (45.7 tonnes). The hull’s overall dimensions were unchanged at 25 feet (7.62 m) long and 13.1 feet (3.99 m) wide.
By September 3rd, 1954, the FV200 test vehicle was ready for trials at the FVRDE in Chertsey. The race was on to get the vehicle ready for its first public display on the 30th of that month. On the 4th, the engine was started and allowed to idle for 10 minutes. It would not accelerate past 2,700 rpm and had to be turned off after the throttle became stuck open. By the 9th, repairs had been made and the vehicle was towed onto the FVRDE test track ready for its first driven trial. Under its own power, the vehicle successfully moved out onto the track. Moving off in 4th gear with the turbine running at 6,500 rpm, the vehicle successfully completed a full circuit of the track in 15 minutes.
Between the 21st and 22nd, P7 ran the same circuit again, achieving a combined running time of 2 hours 3 minutes. In general, the vehicle ran well with only minor issues arising that were easily fixed. Occasionally there were starting troubles, but it was found that the addition of four extra batteries dealt with this. The first major breakdown came on the 23rd. The driver attempted to change from 4th to 5th gear but it would not engage. The vehicle was halted with the driver attempting to get it down into 3rd. Instead of 3rd, it slipped into reverse and jammed. The vehicle then had to be towed to the onsite workshops for repairs.
By the 27th, repairs had been completed. Static and short road checks were undertaken and showed that the vehicle was back in full running order. All that remained was to give the vehicle a fresh coat of silver paint for its public display.
P7 made history when it was demonstrated before a large crowd of military and public spectators on September 30th. The vehicle ran without fault, but it was not pushed too hard, achieving a top speed of just 10 mph (16 km/h). For the test, the vehicle was operated by one man, the driver, accompanied by another man next to him under the mystery hatch. What the role of this man was is unknown. On the 30th, they were joined by FVRDE staff members who sat on the rear of the engine deck. Staff present on that day recalled that the onlooking crowd was visibly impressed. Even the film news company, British Pathe were present to record the demonstration.
Results & Further Trials
Parsons’ turbine had now reached a total running time of almost 12 hours. Through tests up to and including the public display of September 30th, the acceleration of the vehicle was found to be acceptable. Deceleration, however, proved to be a recurring issue. It was far too slow, making gear changes prone to malfunction. The engine was also found to be extremely loud. How loud, exactly, is unknown, but it was loud enough that the operator’s appeared to require ear-defenders (as seen in the video of the 1954 display). Attempts were made to reduce the noise level to 92 decibels or under. Following the public display, running trials were paused and the engine removed from the hull. It was completely stripped down and rebuilt, incorporating new modifications.
By April 19th of 1955, the engine had been reinstalled and P7 was ready to re-commence trials. Despite some initial faults, the engine was running well by May 24th. During tests on this day, the vehicle successfully negotiated 1:6 and 1:7 gradient slopes and performed successful hill-starts.
On June 8th, the final turbine tests were undertaken, consisting of cold and warm starts. Further tests would be carried out utilizing a second turbine engine, ‘No. 2983’. This was an improved engine with much of the initial teething troubles fixed, and an increased output of 910 hp. This increased power would allow P7 to be ballasted in order to compare its performance with the weight of vehicles in operation at the time. The last report from C. A. Parsons came in April 1955. By March 1956, the FVRDE had completely taken over the project. From there, unfortunately, we do not know what happened to the turbine project.
After the Trials
As discussed, we do not know what happened to P7 in the immediate years following the turbine trials. At some point in the early 1960s, P7 was turned into a dynamometer vehicle and served with the Military Engineering Experimental Establishment (MEXE) in Christchurch, on the south coast of England. Strictly speaking, it was not a true dynamometer, but an ‘active’ or ‘universal’ dynamometer as it could be driven under its own power or absorb energy. A standard dynamometer is simply a means of measuring force, moment of force (torque), power, or any combination thereof. This is a chassis dynamometer as it used a full power train on its own, and was basically used not only to measure the engine power of a unit connected to it, but also to calibrate said unit.
To convert it to this role, a new diesel engine was installed and a large welded ballast superstructure was built over the chassis, with a large glazed cab at the front. A large wheel on a pivoting arm was added to the back of the vehicle which was used to gauge travel distances accurately – an upscaled version of a ‘Surveyor’s Wheel’. At some point, the vehicle’s original all-steel tracks were replaced with the rubber-padded tracks of the FV4201 Chieftain. The vehicle was also painted bright yellow and received the new registration number of ’99 SP 46′.
It is unclear how long the vehicle was in operation before it was retired. The last use of the vehicle, however, was an interesting one. The vehicle ended up at The Tank Museum, Bovington. It did not go on display though, it was turned into a commentary box beside the museum’s vehicle arena. For this, a larger cab was built atop the dynamo cab. This is how the vehicle sat for a number of years, before it was scrapped in the early 2000s.
P7 and C. A. Parsons’ engine made history in 1954. The trials proved that a turbine did have a place as the powerplant of Britain’s heavy AFVs of the future. Despite this, the engine type would never be adopted by the British Army. Even today, the British Army’s current serving Main Battle Tank (MBT), Challenger 2, uses a conventional, combustion diesel engine. It was not until the appearance of tanks like the Strv 103, the later M1 Abrams and T-80, that the turbine engine became a front line AFV engine.
Unfortunately, the vehicle no longer exists. Despite its technologically important history, the vehicle ended up being scrapped by The Tank Museum, thus marking the end of a unique chapter in the history of British military technology.
An article by Mark Nash, assisted by Andrew Hills.
The FV200-based turbine test vehicle made history when it debuted on September 30th 1954 before a public and military audience. For the public display, the vehicle was painted in a shiny silver livery, with dark grey highlights on the ‘bazooka plates’ and road-wheels. Illustration produced by Ardhya Anargha, funded by our Patreon campaign.
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