Categories
Cold War British Prototypes

RO2004 Light Tank

United Kingdom (1985)
Light Tank – Partly Built

The RO2000 series of vehicles was a late Cold War attempt by the Royal Ordnance PLC to standardize the vehicle fleet of the British Army and for export to Middle Eastern countries. The central idea of the RO2000 was a common platform encompassing the engine, transmission, chassis and suspension, with just the rear combat module varying between vehicles. The vehicles were meant to be easy to manufacture, mechanically simple and cheap both due to their small size and due to parts commonality.
Of the four RO2000 vehicles, the most potent was the RO2004 light tank, armed with an adaptation of the still-potent L7 105 mm gun made famous by the Centurion.

This is the modular hull of the Vickers RO2000 AFV series of vehicles. (Source: Royal Ordnance/ Tank Museum)

RO2004 Light Tank

The Royal Ordnance RO2004 light tank was to be built on the RO2000 universal lightweight chassis and come fitted with a version the famous L7 105 mm gun firing standard NATO ammunition. While its basic armor is unknown, it was to be upgradeable with a new ‘dynamic armor’ that was in development. The 105 mm gun was to be a low recoil version on the L7 with a new distinct pepper pot-style muzzle break called the Improved Weapon System (IWS) which had been developed in 1989 by Royal Ordnance.
The new gun was conventionally rifled and made from Electroslag Refined Steel (ESR) with a fume extractor, thermal sleeve horizontal sliding breech mechanism, and distinctive pepper pot muzzle brake that reduced recoil forces by 25 percent. Royal Ordnance also offered an automatic muzzle reference system (MRS) that could be fitted to the gun to greatly improve the accuracy of the weapon system. RO also developed. alongside the IWS, a new 105 mm APFSDS (Armor Piercing Fin Stabilised Discarding Sabot) round that they claimed to have a penetration of 540 mm of Rolled Homogeneous Armor (RHA) at a range of 2,000 meters.
A high rate of fire was expected due to the use of a bustle-mounted autoloader coupled with a state of the art gun control and computerized Fire Control System (FCS). Passive Thermal Imaging (TI) and image intensifiers came as optional extras. The Royal Ordnance dynamic armor (not to be confused with the later Electrical Armor of the same name) was, in essence, a mix of a conventional laminated plate with Explosive Reactive Armour (ERA) built into it, providing protection against kinetic and shaped charge attacks. On top of this would also be more conventional ERA blocks as a preliminary line of defense.
The crew of three consisted of the commander, gunner, and driver. The layout was somewhat atypical with the driver front left while the commander and gunner were situated adjacent to each other with the gunner in the normal loader’s location by UK standards. Vision was provided by a panoramic sight for the commander as well as 7 episcopes and an individual laser sighting system for the gunner. The driver had full day-night low light thermal vision (LLTV).
Power was to be provided by a Perkins TV8-640, 320 hp 8-cylinder turbocharged diesel engine coupled through a T320 automatic 6-speed epicyclic gearbox. The top speed was estimated at 55 km/h (34 mph).
The suspension consisted of transverse torsion bars, 5 per side. Each was connected to a pair of roadwheels, leading to a total of five pairs and 10 wheels per side. Two return rollers per side were also present. Later proposals by Royal Ordnance included hydraulic adjustable suspension.


The RO2004 Light Tank. This illustration was produced by Brian Gaydos, funded by our Patreon Campaign

Conclusion

A single turret of a RO2004 was built and displayed. The vehicle was advertised at many arms expositions and even proposed to the British Army but, like the rest of the series, did not receive any orders. The fate of the built turret is unknown. The Royal Ordnance PLC was bought by British Aerospace in 1987, currently known as BAE Systems.

Side drawing of the RO2004 light tank taken from a Royal Ordnance RO2000 series Technical Datasheet.

Specifications

Dimensions (L-W) 6.3 x 2.81 x 2.41 meters
Weight 21.5 tonnes
Crew 3 (Driver, Commander, Gunner)
Propulsion Perkins TV8-640, 320 hp 8 cylinder turbocharged diesel with T320 automatic 6-speed epicyclic unit
Suspension Transverse torsion bar, 5 per side, telescopic dampers 1,5
Speed 55 km/h
Armament 105mm Low Recoil Gun IWS
1x 7.62 mm Hughes chain gun
Total Production None built

Sources

Royal Ordnance files relating to the RO2000 program in the Bovington Tank Museum archives
Royal Ordnance RO2000 series Technical Datasheets
Armoured trials and development unit, Bovington Camp, Report on the RO2000 series, 9 June 1986
Royal Ordnance RO2000 sales brochure
Royal Ordnance RO2000 press release

Categories
Cold War British Prototypes

RO2001 Self-Propelled Gun

United Kingdom (1986)
SPG – 1 Built

The RO2000 series of light vehicles came about as a government evaluation into developing a new generation of vehicles known as Future Family of Light Armoured Vehicles (FFLAV). FFLAV began to progress swiftly after the 1990-1991 Gulf War, which had highlighted key areas of concern in the older vehicles used by the Army, notably the FV430 and CVRT series which were already three decades old. FFLAV was to streamline at least three key series of vehicles into one family; the FV430 series, the FV510 Warrior family, and the CVRT (Combat Vehicle Reconnaissance Tracked). This would have left an opening for up to 7000 replacement vehicles, leading to one of the largest modern defense contracts ever issued.

122 mm Vickers R02001 Artillery Self-propelled Gun prototype (Source: Royal Ordnance/ Tank Museum)

The RO2001 Self Propelled Howitzer

The Royal Ordnance RO2001 self-propelled howitzer was designed for the export market and was based on the UK’s RO2000 universal chassis. Had it been accepted for UK service, it was proposed to mount a L13A1 105 mm gun similar to that of the FV433 Abbot Self Propelled Gun or, alternatively, the Royal Ordnance L118 light 105 mm gun.
The export version for Egypt was meant to be armed with a 122 mm D30 howitzer which was manufactured in Egypt by Abu Zaabal Engineering Industries Company. It was based on the Russian designed howitzer. It had a computerized gunsight system for both direct and indirect fire modes.
Although the prototype was fitted with the 122 mm D30 howitzer, the vehicle hull and superstructure could be adapted to fit most 122 mm howitzers. The superstructure and gun mount enabled the gun to have a traverse of + 30 deg from the centreline: +70 deg elevation and -5 deg gun depression. There was enough storage space for 84 rounds for the main gun.
The hull was to be rolled steel with the driver to the front left and the other 4 crew including commander and loaders in the rear. Unlike the Abbot, the RO2001 did not have a fully rotating ‘turret’, with the rear superstructure being built up and designed to fit a variety of weapons or possible refits including the D30 122mm gun. Secondary protection was by means of a 7.62 mm machine gun as well as L8 grenade dischargers with VIRSS (Visual and Infrared Screening Smoke).
It was powered by a Perkins TV8- 640 8-cylinder turbocharged diesel engine but had a maximum horsepower of 320 hp. It had a maximum road speed of 55 km/h. Fuel tank capacity 454 liters. The transmission was an engine – gearbox coupling with a Twyflex centrifugal clutch. The T320 gearbox had self-changing gears. It was an automatic 6-speed epicyclic unit with manual hold controls. It had regenerative, disc brake steering. The main breaks were Lockheed disc brakes that were hydraulically operated. The suspension consisted of traverse torsion bars: 5 stations per side with telescopic dampers on the front and rear wheel stations. The track was cast steel link drive pin type with rubber bush inserts and rubber road pads.
The vehicle electrical system was a screen suppressed and waterproofed 24V electrical system. There were two 6TN batteries giving 100 amp-hour capacity for engine starting. An additional two 6TN batteries gave 100 amp-hour capacity for auxiliary systems.
The prototype RO2001 lightweight artillery self-propelled gun (SP122) fired over 300 rounds during trials in Egypt and covered 10,000 km. It was shipped to Britain so that it could be put on show at the British Army equipment exhibition arms fair in the summer of 1986. It stood on the Royal Ordnance stand next to the 120 mm mortar (RO 2003).

Front view of the 122mm Vickers RO2001 Artillery Self-propelled Gun (Source: Royal Ordnance/ Tank Museum)


The RO2001 Self-Propelled Gun (SPG). This illustration was produced by Brian Gaydos, funded by our Patreon Campaign


Conclusion

Only one vehicle was built and was sent to Egypt, where it was fitted with a D30 howitzer made by Abu Zaabal Engineering Industries with sighting systems for both direct and indirect fire. However, no advanced fire control was attached to this version. The competition was from a US platform but neither was accepted for service. Unfortunately, like so many good ideas put forward, political bickering and incompetence saw interest wain and the UK once again began the ongoing waste of money that became synonymous with its research and development process.

Artist’s impression of the 122 mm Vickers RO2001 Artillery Self-propelled Gun. (Source: Royal Ordnance/ Tank Museum)

Specifications

Dimensions (L-W-H) 6.2 x 2.81 x 2.70 m (excluding gun)
20 ft 4 in x 9 ft 2 in x 8 ft 10 in
Armament 105 mm or 122 mm Howitzer
7.62 mm or 12.7 mm Machine-Gun
Traverse 30° left and right
Elevation +70°
Depression -5°
Crew 5 (Commander, Gunner, Driver, 2 x Loaders)
Optics One vision periscope, 360° panoramic sight, day/night driving optional
Weight 20 tonnes
Ground clearance 0.46 m
Maximum road speed 55 km/h (34 mph)
Maximum gradient 30°
Maximum trench width 2.2 meters
Maximum vertical obstacle 0.75 meters
Ground pressure 0.5 kg/cm
Propulsion Perkins TV8-640, 320 hp 8 cylinder turbocharged diesel with T320 automatic 6-speed epicyclic unit
Main brakes Lockheed disc brakes
Fuel capacity 454 liters
Steering Regenerative, disc brake steering
Suspension Transverse torsion bar, 5 per side, telescopic dampers 1,5
Track Cast steel link dry pin type
Radio Clansman or customer-specific
Total Production One built


Side view of the 122mm Vickers R02001 Artillery Self-propelled Gun (Source: Royal Ordnance/ Tank Museum)

Sources

Royal Ordnance files relating to the RO2000 program in the Bovington Tank Museum archives
Royal Ordnance RO2000 series Technical Datasheets
Armoured trials and development unit, Bovington Camp, Report on the RO2000 series, 9 June 1986
Royal Ordnance RO2000 sales brochure
Royal Ordnance RO2000 press release

Categories
Cold War British Prototypes

RO2000 Platform

United Kingdom (1986)
Multi-Role Platform – Several Built

The RO2000 series of light vehicles were a part of a government initiative into developing a new generation of vehicles, known as the Future Family of Light Armoured Vehicles (FFLAV). This was a follow up on the Family of Light Armoured Vehicles (FLAV), whose origins can be traced back to the 1980s when it had failed to deliver a workable platform.

This is the Vickers RS2000 AFV series of vehicles modular hull. (Source: Royal Ordnance/ Tank Museum)

FFLAV

FFLAV began to progress swiftly after the 1990-1991 Gulf War. This conflict had highlighted key areas of concern with the older vehicles used by the Army, most notably the FV430 and CVRT series which were already three decades old. One highlighted area of concern was the overlapping roles that the equipment fulfilled, with roles duplicated on the FV430, CVRT, and even old Centurion types in service. Not only did this lead to a bigger logistic footprint than required, but was also expensive to maintain and required extensive manpower and training in familiarity to keep them operating successfully.
The MOD concluded that, if the units could be consolidated by using a more coherent approach and creating a family of vehicles that fulfilled all roles on a universal chassis, it would go some way to reduce the issues noted above.
The FFLAV was meant to streamline at least three key series of vehicles into one family; the FV430 series, the FV510 Warrior family, and the CVRT (Combat Vehicle Reconnaissance Tracked). This would have meant that up to 7000 replacement vehicles would have been needed, leading to one of the largest modern defense contracts ever issued in the United Kingdom. Such an opportunity did not go unnoticed and nearly all the major defense firms showed interest. Given the size and scope of the project, these firms began to form consortiums to increase their odds of winning any sole contract for the program. However, at this stage, it was still officially a study and not an official development/procurement request.

RO2003 Self-Propelled Mortar based on the RO2000 platform, the other vehicle built on the platform. Source: Technical spec sheet on sale on Ebay
Three key consortiums were formed:

  1. Alvis/Hagglunds/Panhard/ENASA
  2. GKN/Mowag
  3. Royal Ordnance PLC/BAE

As is typical in any large multinational defense design and procurement project, the three consortiums promptly settled on trying to push their own nation’s domestically-made vehicles as the best possible option, while retaining civility amongst themselves.
The first consortium chose to propose the Panhard VBL, Alvis CVRT upgrades, the ENASA BMR-600, and Hagglunds CV90. The second one submitted the GKN Warrior 2000 and MOWAG’s own Piranha APC.
However, the third team was the only group to seemingly understand that the MOD did not want yet more variants of the vehicles they already had and wanted to reduce the existing collection into one single family. It was the Royal Ordnance PLC that drew up and actually made some of the RO2000 series.
Despite various levels of research being carried out and several pre-production vehicles having been made, the UK once again decided to go through a different route and opted to proceed with the fiscally disastrous MBAV, MRAV, TRACER and later FRES programs.

Black and white drawing of the RO2002 APC variant.


The RO2000 common platform without any combat module installed on the back. This illustration was produced by Brian Gaydos, funded by our Patreon Campaign

RO2000 Series

According to a report from the Armoured Trials & Development Unit at Bovington, the RO2000 series stemmed from a design, called SP122, done by the Royal Ordnance for a self-propelled howitzer for the Egyptian army, a design which would become the RO2001. The vehicle was meant to be built in Egypt, the industry of which was not well developed, and thus the vehicle had to be simple and easy to manufacture. It was then decided to use the chassis for a family of vehicles, four of which would actually be designed. Other reports indicate that all the vehicles were designed at the same time and only after that was the SPG version offered to Egypt.
The basic RO2000 vehicle had a steel chassis, with a Perkins TV8-640 V8 turbocharged diesel giving 320 hp coupled to a 6-speed epicyclic automatic gearbox, both placed at the front of the vehicle, leaving the rear space empty for the addition of the fighting compartment. The suspension consisted of 5 double wheels mounted on torsion bars, with an idler at the rear and two return rollers per side. These features were meant to be simple, cheap and low maintenance. It was also advertised as being easily upgradeable for the needs of the British army, mainly because the stock configuration was technologically primitive for the day and era. The vehicle could manage a gradient of 30o, a trench measuring 2.2 m or an obstacle 75 cm high.
The armor values are not specified, although they were probably very low given the low weight of just 13.5 tonnes for the base vehicle. However, it was advertised that a new armor package could be installed to optimize protection against kinetic and HEAT shells.
Maintenance-wise, the vehicle was meant to be easily pulled apart, taking just 40 minutes to take out the engine, 35 minutes to take out the gearbox and 25 minutes to take out the final drive unit, all with ‘the simplest of equipment’.
The RO2000 chassis, probably in the form of the RO2001 howitzer, underwent at least 10,000 km of testing in ‘arduous conditions’.

Side drawing of the RO2004 light tank.

Conclusion

The RO2001 and RO2003 were built, while RO2004 was only partially constructed. The vehicles were displayed at various private arms exhibitions. On paper, they filled the role needed and would have been valuable assets to the British Military. Unfortunately, like so many ideas put forwards, political bickering and incompetence saw interest wain and the UK once again began the ongoing waste of money that became synonymous with its research and development process.
However, the technical simplicity and small size of the RO2000 series were double-edged swords, as they also meant that the vehicles were seen as unsophisticated and hard if not impossible to upgrade and improve. The Royal Ordnance PLC was bought by British Aerospace in 1987, currently known as BAE Systems.

RO2001 Self Propelled Gun that was pitched to the Egyptian army, based on the RO2000 platform. Source: Think Defence

Specifications

Dimensions (L-W) 6.2 x 2.81 meters
Weight 13.5 tonnes
Propulsion Perkins TV8-640, 320 hp 8 cylinder turbocharged diesel with T320 automatic 6-speed epicyclic unit
Suspension Transverse torsion bar, 5 per side, telescopic dampers 1,5
Total Production None built

Sources

Royal Ordnance files relating to the RO2000 program in the Bovington Tank Museum archives
Royal Ordnance RO2000 series Technical Datasheets
Armoured trials and development unit, Bovington Camp, Report on the RO2000 series, 9 June 1986
Royal Ordnance RO2000 sales brochure
Royal Ordnance RO2000 press release

Categories
Cold War British Prototypes

Comet Crocodile

USA/Great Britain (1946)
Trial Tank

The Crocodile flamethrower was a successful piece of equipment and is probably best well known for being used by the Churchill tank, and to a lesser extent the M4 Sherman, during World War 2. Immediately after the war, however, a new Universal tank, the A41 Centurion, was being delivered and was replacing the A34 Comet and other tanks as the mainstay of Britain’s tank fleet for a generation to come. The Centurion was significantly faster and a modern tank compared to the ponderous and archaic design of the Churchill, and it makes good military sense to have a single platform for a variety of weapons rather than multiple specialist single-role platforms.
One role the Churchill had performed well was that of the Crocodile, where its slow speed was not a hindrance. If the Centurion was going to replace all the older types of vehicles completely, it would need to be evaluated in the Crocodile role as well. With a view to this, in April 1946, the British military took a standard A34 Comet and having made minor modifications for the purposes of towing – namely the fitting of the Crocodile towing link – and attached a Crocodile fuel trailer to it.

The previous Crocodiles. The famous Churchill on the left with the lesser known Sherman version on the right.
There is no information to suggest that the flame projector itself was ever fitted, and photographs of the project show that the test vehicle retains the hull BESA machine-gun mount rather than the flame projector. This confirms that this vehicle was a non-functional flamethrower prototype and just a test vehicle for towing rather than an actual flamethrowing tank in its own right. This is because the key aspect of the Comet which the Churchill lacked was speed. This was to be a speed trial to test the trailers being towed by a fast tank, like the Comet, and indeed, to be later towed by the Centurion which was already in production at the time.

The Trial A34 Comet fitted with Crocodile Flamethrower trailer. Photo: The Tank Museum.

The Tests

A34 Comet serial number ‘T.336092’ was used for the trial. It had been fitted with 15 ½″ wide tracks and a new final drive with the ratio 4.5:1. This was to be a speed and endurance trial for tank and trailer alike along Long Valley, Surrey, in Southern England.
Trials commenced in April 1946 as the modified A34 ‘Crocodile’ set off on its 500 miles (805 km) journey along the course at top speed of which half was to be on the road and a half to be across country.

Close up view of the Crocodile flame projector during trials on a Churchill tank, April 1944. This is notably absent on the Comet indicating that a conversion to a flamethrower did not take place. Photo: IWM

Close up of the coupling as fitted to the A.34 (seen here on a Churchill). The notable difference is the fuel pipe with is not believed to have been fitted to the A.34 as it had no projector. Photo: Mark Nash

Results

The tests proved too extreme. While it is not known if the trailer was even loaded, it is likely it was ballasted to match the weight of a full trailer. Hauling one full of fuel was probably just too hazardous. The ground was hard and dry to start with, becoming progressively muddier with occasional stops to check on the condition of the trailer and hitch. At the 148-mile point, the problems began. The bolts securing the coupling started to work loose from the vibration and had to be re-tightened. This happened again at the 191-mile point with loosened bolts and one which had completely sheared off, and again a retightening after 260 miles.
After 100 miles of off-road driving (300 miles of the 500 miles total), the entire coupling failed. The Tank Museum at Bovington recounts that the tests ended when the trailer broke its axle and damaged its tires “while crossing a half-timbered trench against a 26″ step”.
Army Trials Report No. 1771 however, provides an alternative account. The shock, vibration, and forces on the coupling during the journey meant that the entire coupling link sheared its securing bolts and came off the trailer, causing damage to the bottom housing plate. Whichever account is correct, the trials for that trailer were over.

A photograph taken during the trials shows the trailer completely off the ground towed over a timber beam at high speed by the Comet, something inadvisable full of fuel. Photo: David Fletcher
The tank too had suffered from the severity of the tests with the steering brakes being severely scored (deep radial scratches indicating severe wear) and damaged, but the remainder of the mechanicals remained in good condition. Despite the high speeds, long journey, and towing a trailer, there was no evidence of the wheels or wheel bearings being badly worn, and despite the high wear on the steering brakes, the drivers reported that the steering was normal with no adverse effects on- or off-road. With a completely broken coupling though, the trial had to end before it had been completed.

Close up of the Crocodile trailer being towed by a Churchill tank in August 1944. Photo: IWM

Conclusion

The test of the A34 with the Crocodile fittings was neither a success nor a failure. The tank survived the extreme tests rather well and the trailer had never been intended for such rough treatment, yet survived 300 miles of the roughest possible handling. Other than the mechanical strength of the coupling there was nothing, in theory, preventing the use of the trailer at high speed other than the terrifying nature of it going wrong.
A report following the test concluded that the standard Crocodile trailer was not capable of withstanding fast towing or normal cross country towing, but that a fix was already in the works. A new one-piece fully cast connecting link was designed to replace the existing bolted type and it was suggested that a further trial of a trailer with that link should be tested, although it does not appear to have taken place.

Centurion Crocodile tank during trials. Photo: Tank Museum
The Centurion tank was also eventually trialed with the Crocodile trailer equipment as well, building on the work done on the Comet Crocodile trailer towing trials. The A34 Comet Crocodile was, therefore, not a true flamethrowing tank in its own right although there was nothing to prevent the flame equipment being fitted if the military had chosen to do so. She was really just a towing modification test rig for the Centurion Crocodile but flamethrowers had mostly fallen out of favor with the British military by then anyway. There is no information to suggest that the Comet tank was ever even planned to be fitted with a flame projector unit and no special name or mark was applied to the modified A34 used.

Specifications

Dimensions
L x W x H
6.55 m (w/o trailer) x 3.04 m x 2.67 m
(21ft 6in x 10ft 1in x 8ft 6in)
Total weight, battle ready 33.53 tonnes (32.7 long tons)
Crew 5 (commander, driver, gunner, loader/radio op, hull gunner)
Propulsion Rolls Royce Meteor Mk.III V12 Petrol/gasoline engine, 600 hp (447 kW)
Suspension Christie system
Top speed 32 mph (51 km/h)
Range (road) 155 miles (250 km)
Armament Flame Thrower
1x 7.92 mm (0.31 in) BESA machine guns
1x Flame thrower
Armor From 32 to 102 mm (1.26-4.02 in)
Total Production 1

Links & Resources

Tank Museum, Bovington
A.34 Comet – A Technical History, PM Knight (LINK)
British Battle Tanks, David Fletcher
Osprey Publishing, New Vanguard #136: Churchill Crocodile Flamethrower, David Fletcher


The Comet Crocodile trial vehicle. Illustrated by Alexe Pavel, based on an illustration by David Bocquelet.

Categories
Cold War British Prototypes

A46 Light Tank

United Kingdom (1946-47)
Light Tank – None built

The origins of the A46 and its descendants, the FV300 family, began in the middle of 1943 during the Second World War. At this point, the United Kingdom and the United States discussed that for a while at least, the US would provide enough tanks and war materials so that the UK could begin to scale back its industrial output that had been operating in high gear since the retreat from France and concentrate on new industrial capacity.
The UK, whilst seeing the attractiveness of such an offer in the short term, did not want to be indebted more than it was to the US after having grudgingly been compelled to share all of its indigenous technology so far. The thought of being further chained to its creditors was not something the UK wanted. It’s also worth noting that the US believed the UK would lose to Germany early in the war and, as such, regarding payments of Lend Lease, they did not want payments in pound sterling. UK gold reserves and the liquidation of British assets in America had, instead, to be sold to the US at a fraction of their value industry. The final debt would be US$1.2 trillion to be repaid finally in 2006.
The UK had decided that further reliance on US technology and control was unacceptable both from a sense of fiscal foresight and partly out of a wounded sense of national pride. Britain, therefore, proceeded to build and develop light and medium tanks of its own. Whilst many of American Lend-Lease tanks were adequate, the UK also desired to adjust the balance in its own forces and sense of self-dependence by producing its own light tanks to replace the American M3/M5 light tanks in service.

Background

The War Office settled on designing the next generation of light tanks, the platform chosen was to be based on the A17 Tetrarch and A25 Harry Hopkins light tanks that were in service, notably reusing their unusual steering systems. This required any steering to be done by curving the track via a steering wheel along with additional skid steering using Girling internal expanding brakes that could be used for sharp turns. The whole suspension was carried on four bulbous independently sprung wheels on each side.
The ‘Tetrarch’ or ‘Light Tank Mk VII A17’ had been produced by Vickers-Armstrong in the late 1930s and saw limited action in WW2. Armed with a 2 pounder (40 mm) gun and only lightly armored, its overall career was unremarkable but it saw limited service with the UK and Soviet forces and smaller trials in Switzerland.
The second tank, Light, Mk VIII, A25 also known as the ‘Harry Hopkins’ after President Roosevelt’s chief diplomatic advisor, was a later design also built by Vickers-Armstrong in 1941 and used many of the lessons gained in developing the A17’s.

The failed Harry Hopkins tank was the forefather of the A46 Light tank. Source: tankmuseum.org
The A25 did not fare much better. During the early design phase, the light tank concept was out of favor due to the losses in France the prior year and ongoing problems with the vehicle’s development which led to large delays. By 1943, only six A25s had been produced and the UK was now equipped with the American M3/M5. Once the order in 1943 came through for a late war/post-war light tank to be developed, Vickers quickly picked up the contract, as, although its previous light tanks had not been a combat successes, they did employ one of the essential criteria listed; namely to employ a steering system that required little power such as that found on the A17 and A25. Vickers must have been laughing all the way to the bank with that contract.
The official reason for wishing to reuse this steering system stemmed from the fact it required a smaller engine and lighter transmission over conventional ones. Thus, a smaller frame could be built, which was highly desirable in a light tank. This feature was particularly important for the A46, which was expected to be air portable without disassembly, although the ability to be easily dismantled prior to transport was included if required for long distance flights.

Development

Lessons from the Tetrarch and, to a lesser extent, the M3/M5 tanks had also been taken into consideration. Vickers decided they wanted a gun capable of being effective against other light and medium tanks yet have a useful High Explosive (HE) round and ideally share a commonality in parts or munitions with guns in service. The new vehicle was therefore to mount the 77mm QF gun which Vickers had been testing on the new A34 Comet medium tank. The new 77mm gun had been given the highest priority to A46 development initially, over that of even the Comet. Although debates were held at the Tank Board about this, where some saw the turretless Stuarts tanks fulfilling these roles while the UK was at war and felt instead that the 77mm should be prioritised for the Comet which should actually see combat.
Two prototypes were to be designed, a version with a rear mounted engine and another with a forward mounted engine. The gun tank type would initially have a rear engine whilst the load carriers and self-propelled guns would have front engines. Vickers happily agreed as it saw future growth in this system and it was one of the UK’s first modular designs that could allow the chassis to be reused for a variety of roles. Although Vickers had not even presented any official plans, the War Office ordered 80 to be built in 1944.

Line drawing of the A46 Light Tank based on the original development files and blueprints. Source: Ed Francis
Fast forward to November 15th 1944, and the 44th meeting of the Tank Board took place. It is recorded in the minutes that a meeting had taken place at Chertsey on the 14th November to consider the paper proposals as requested for the light tank roles. Mr. Little explained the layouts were in the same building and the board agreed to review them after the meeting was over. The next minutes held on 3rd January 1945 noted a mock-up of the gun tank would be ready by the end of the month for inspection and that no real issues had thus hindered the project. Production should have begun around mid-1946. It was noted during minutes that the light tank concept “looked extremely good and should appeal psychologically to the troops”.


Vickers Light Tank A46. The resemblance to the Tetrarch and Harry Hopkins can be seen in the tank’s running gear. Illustration by Yuvnashva Sharma, funded by our Patreon Campaign

The A46

The 46th Tank Board minutes also give the first full description of the A46, or to use the Vickers codes; ‘M132’ and ‘M131’. The former had a front engine and the latter the rear mounted block.
Vickers had managed to build one full-size mock-up gun tank before the war’s end, as well as a series of wooden display models. By late 1944, the War Office was looking at three new lines of tanks. These would consist of the A45 series, which would go on to become the FV200 heavy line, the A41 line based around the universal tank concept including Centurion, and the new Vickers light line.
Each of these lines would have its own gun tanks, command, bridge layers and support vehicles. By 1946, a new threat began to loom on the horizon with American and Soviet clashes of ideology mounting. Europe was still in tatters but, with the Soviet threat looming, the British began a slow but steady rearmament program. The aim was to do away with much of the wartime stock and instead to focus on this series of standardised vehicles. Each class and category would come under a new Fighting Vehicles designation commonly referred to as an ‘FV’ number.
These were detailed in the Fighting Vehicle Divisional notes 15, dated November 1946, where it was outlined how all vehicles were to be classified in categories between 1 to 19 with 00 as the basic platform and subsequent numbers to be sub-variants of this. For example, FV200 was to be a series of heavy vehicles with ’00’ the stock model, FV201 the gun tank etc. Each possible vehicle combination had been considered although the numbers would stretch far further than the original 19 and deviate over the years. A46 therefore has the dubious honor of being the last ‘A’ series number. With these FV numbers, a standard series of engines would also be introduced. Heavy tracked vehicles were to have the 800 hp Meteor (fuel injected) engine, medium tracked vehicles the 350 bhp Meteorite and light tracked vehicles the B80 Rolls Royce.
By 1947, A46 testing had switched to a front-engined arrangement and design progress was making steady headway. It was hoped that all vehicles developed from this would have the same layout. The engine and gearbox would be to the front right-hand side and connect to the rear drive sprocket via a centreline shaft. Vickers decided to add stowage bins to the back of the vehicle to increase ammo capacity and modified their drawing accordingly. It was realized that a three-man crew would have been too cramped for the long distance type of activity a light recon tank might have been required to carry out. As there was no compromise on the gun, Vickers passed it over to the Elswick department who began working on an autoloader for the 77mm gun.

The Vickers Elswick works were a part of the development of the A46 light tank took place. Source: Wikimedia Commons

Fate

A46 did not go much further from this point. Work had begun on a full size mock-up, however. The design specifications had changed completely and the project had become an experimental fully enclosed APC named CT-26 that still retained the front mounted engine and track/suspension system from A46 but was otherwise its own project from now on. The requirement for a new light line would instead move over to a new family, the FV300 series.

The A46 Light Tank project morphed into the CT-26 APC seen above. This vehicle was not successful either. Source: Aviarmor.net

Specifications

Dimensions (L-W-H) 16 ft (21ft 5in Gun Forward) x 9 ft 6 in x 6ft 6 in
(4.87 x 6.52 x 2.89 m)
Total weight, battle ready 16 tons (32,000lbs)
Crew 4 (commander, Driver, Gunner, Loader)
Propulsion (various choices) Engine General motors 6-71M Diesel engine producing 207 bhp at 2000 rpm
Rover meteorite Mk 204 1,099 cu in (18.0 L) petrol V8 at 350 hp
Rolls Royce Meteor supercharged (Merlin) V12 engine. In excess of 1000 bhp
Transmission Splicer synchromesh gearbox. (5 forward, 1 reverse.)
Speed 28 mph
Armour Turret: front 75mm, sides 50mm, rear 40mm, top 14mm
Hull: upper 76mm, lower 50mm, side 25mm, upper 19mm, rear lower 25mm, top Front 14mm, floor 19mm
Armament 1 x 77 mm HV rifled gun with 50 rounds
1 x 7.62mm coaxial machine gun with 2,250 rounds
Elevation: +20/-12 Degrees
For information about abbreviations check the Lexical Index

Sources

A46 development files at the Bovington Tank Museum Archives

Categories
Cold War British Prototypes

FV4010 & Malkara

United Kingdom (1954-60)
Heavy Tank Destroyer – 3 Hulls Built

The story of FV4010 and its missiles begins in the strange post-war phase, following the collapse of the Third Reich and the Rise of the Soviet Union as the perceived global antagonist. It had long been appreciated during the Second World War that the Soviets were capable of making excellent tanks and in large numbers but despite a few mutterings at the top levels nobody was quite prepared for how quickly relations between the Allies would cool off and then fall apart altogether. The first real taste of what the UK might face came during the victory parades which passed through Berlin in 1945. The US and UK had already displayed their armor when columns of IS-3 tanks drove past the spectators and they came as quite the shock.
Those that were able to get a good view, including a number of intelligence officers, noted that these new tanks were, at least on paper, far more powerful and numerous than anything the Allies had encountered, including the German heavy tanks which had caused them quite a headache. With their excellent armor, large 122mm guns, good mobility, and huge production capacity, the IS-3 sent both the UK and the US into a tank designing frenzy focused on how to combat these should either side decide to mobilize.
Two distinct lines of thought began to evolve. The first involved the use of conventional kinetic energy (KE) guns to defeat the Russian armor. These would be based on the L1 120mm gun, itself based of the US M58, and a temporary, but not satisfactory solution had been found in the FV4004 Conway tank destroyer. An even larger platform was proposed to be built on the FV200 chassis known as the FV215 Heavy Tank Destroyer wielding the L4 183 mm Anti-Tank gun, the largest dedicated tank killing gun ever made. A more financially prudent line of reasoning was to use Anti-Tank Guided Missiles (ATGM’s) on tank chassis already in service.

Early and late FV4010 heavy missile tank destroyer versions. Drawings by Ed Francis based on original documents held at the Bovington archives.

Development

FV4010’s birth begins sometime around the 32nd FVDDL (Fighting Vehicle Design Department Liaison) report. In the report, the notion of a mobile platform developed to mount very large guided missiles able to tackle any Soviet tank in service or likely to enter service in the foreseeable future is mentioned. Design work had already been carried out by several FVDD groups and Tank Technology Officers at the School of Tank Technology (STT) in the UK. These designs, such as the Cento, Apollyon, and Cerebos, were exercises for just such a vehicle and, as such, a lot of preliminary work had already been carried out.
The 34th FVDDL report dated July 1955 recorded that preliminary design investigations into a tank-sized vehicle with the FV or Fighting Vehicle reference number 4010 could soon be carried out. No clear description is given at this stage other than it should ideally carry 20 guided weapons or if this were not advisable that a smaller tracked vehicle, able to carry 3 or 4 missiles, should also be considered. This smaller version would turn out to be the FV426. The vehicle and its missile launching arm were actually built and the mock-up missile tested for weight and balance. Sadly, it ended up as a range target at Lulworth before being recovered by the Tank Museum, which promptly chopped the launching arm of and left it as a semi-restored FV400.
The hull chosen for FV4010 was to be Centurion based, much like those in the STT papers, although a smaller version using the A34 Comet chassis was considered. The Comet version was to mount three to four missiles on launching rails on a turretless hull. One such vehicle was reportedly sent out to Libya in the 1950s for testing. However, to date, no further reliable information or photos have surfaced. The one thing the FV4010 and FV215 did have in common was that both platforms were to be heavily armored as both were built around the weapon first and foremost, which in this case was the Malkara missile.


Two original drawings of the early Centurion Mark III-based FV4010 missile tank destroyer. Source: User Ogopogo on the Facepunch forums, initially discovered by Mike Verrel

The Missile

The development of the Malkara missile, a heavy anti-tank wire-guided weapon system, began in 1952 at the Government Aircraft Factory (GAF) in Australia, along with the Aeronautical Research Laboratory (ARL) and Weapons Research Establishment (WRE) which were working on a heavy missile named Project J. This was a radio-guided 6ft (1.8 meter) long, 8 inch (203 mm) missile with a 55 lb warhead and a total weight of 173 lb (78 kg). Australia had also been working on a smaller ATGM known as Project E, a 70 lb (31.7kg) wire-guided missile with a 15 lb 4.5 inch (6.8 kg – 114 mm) HEAT warhead and a maximum range of about 2000 yards (1.8km).
The missiles creator was Dr. William Butement CBE who had taken over the role as the first Chief Scientist in the Defence Scientific Service of the Australian Department of Supply and Development in April 1949. Before this, he had been living in the UK, serving the Crown during the Second World War where his work on using radar to track targets and direct searchlight made him just one of the many unsung heroes of that war.
Although he assumed a more managerial role during the initial Malkara development, he was responsible for the semi-solid paste fuel used to power the missile and is oft quoted as giving the platform the name Malkara, an Aboriginal word meaning shield. The weapon’s guidance and control were developed by Prof J.M. Evans OAM, a research scientist specialising in the stability and control of flight vehicles at the ARL, and Chief Designer of Malkara’s shape and performance.
The UK, meanwhile, was running a parallel project called Heavy GW (Br), as well as a smaller HEAT based version named Light GW (Br), similar to projects J and E. Heavy GW was to mount a 7.5 inch (190 mm) 60lb (27kg) HESH warhead. With a 2ft long warhead, this missile was going to measure in at some 8ft (2.4 meters) long! With both teams working and operating on near identical projects, it was decided to drop one and merge with the Australian project. Those working on the UK’s version were sent over to Australia to begin testing at the Woomera missile range, a journey that still took over a week by air alone.
The Malkara missile itself was and remains the largest wire-guided anti-tank missile of its type ever made. Its 8 inch (203 mm) HESH warhead has a whopping 56 lbs (25 kg) of explosive filler alone. To put that into perspective, a modern 155mm HE shell has about 15 lb (6.8kg) of filler. This ensured any target struck by Malkara was, if not destroyed outright, left unable to take part in the battle any longer. Later tests against Conqueror MBT range targets cracked the front glacis in half. The UK ordered 150 of these missiles outright.

A Carrier For the Malkara

With the missile in place, a series of design projects were started and a rough idea of what they wanted was drawn up. The first iteration was based on a Mk III Centurion and consisted of a well-sloped casemate mounted to the rear, with the engine placed forward. The missile was assembled inside and came out at a 45 degree angle from the rear, facing up. This version often creeps up on the internet as being the actual final platform. A simple glance would inform most that there would barely be enough room for the crew, let alone 20 missiles. The final design mentioned below would be built on a Centurion Mk VII.
Before they got to chopping up perfectly good tanks, the team decided that the best approach would be to build up the basics of the fighting compartment and how it would all work. Unlike the Americans, who had the budget to build a vehicle from scratch only to then discover it didn’t work, the UK placed a lot of emphasis on detailed drawings, followed by wooden models, mockups, soft steel shells and then production. Using this approach, each phase could be stopped easily at minimal cost, obvious faults found and inevitably allow for the usual political interference that comes with any AFV development.

One of the few images of the FV4010 available online. Although often presented as the final version, this is an earlier variant based on the Centurion Mark III. Source: Warthunder forums.
The team decided to build the fighting compartment as a complete module with launching arms and stowage, but the rest of the vehicle could wait as it was not expected the Centurion would change so radically over the next few years. In the meantime, the mockup was mounted on a standard 4 wheeled truck chassis with a generator to the front for power, where the engine would be in any finished design. This, it was reasoned, would allow them to iron out any faults and issues with launching and other parts of the vehicle.
The FVDDL report number 35 dated June 1956, noted the first of the mock-up hulls was ready to go to Australia and it was planned to have at least three of these mock-up’s built and the firing platforms then tested in both Woomera and at the Lulworth ranges in the UK. They were fully fitted and furnished inside to the FV4010 specs, with every detail in place including spare missiles (wooden), crane arm, cupolas and even provisional stowage. The first rig was mostly made of wood and the second of mild steel armor. FVDDL report 36 dated June 1957 states the mobile test rig was now equipped to fire both Malkara and Orange William and a second rig was nearing construction for Malkara trials for early 1958.
Meanwhile, back in Australia, FVDDL report 36 from June 1958 states that test rig one had expended all its munitions and test rig two was now up and running with some 150 missiles to be fired at the Long Range Weapons Establishment, Woomera. These missiles were essentially duds made out of wood and concrete. After firing, they could be recovered and reused, with only the rockets motors replaced.
Unlike the first rig, the stage 2 rig was armored all round and had a working butterfly hatch on top. This allowed one missile to be fired onto the target while a second was being prepped below. Once fired, the launching arms would rotate around 180 degrees on a pair of centrally mounted pinions and a new missile would be in the launch position.
Each missile came in several parts for storage, with the body and wings separate. Each of the four main wings and four secondary fins were clicked onto the missile, once the butterfly launcher had rotated a cable was pulled out and the missile was now armed. The total time for each missile to be laid, fitted and rotated into firing position was 15 seconds. The whole rotation was powered, although it could be done by hand in an emergency. Once on the hull roof, the missile could be panned left and right 30° from within the hull.

Sources

Assorted Malkara development papers, Bovington
Assorted FV4010 development papers, Bovington


Malkara missile and one of the FV4010 test rigs in the bottom half. The images were taken in June 1960 at the Royal Armoured Corps Centre in Lulworth. Source: Ed Francis

Loading/Firing Procedure

1) Attach missile to underside launching plate, allow missile amplifier plate to heat up – max 10 seconds.
2) Connect firing circuit connection
3) Connect wings and fins
4) Missile control wire plug placed in the clip on the underside of the missile.
5) Launching plate to be turned over-loader makes sure arms are clear
6) Control wire and plug to be transferred from the plate to roof point
7) Connection points retract
8) Programmed flight data added, wind speed, temp, elevation etc.
9) Missile fired, launcher plate revolved to present fresh missile.
Three mounting points were provided for the missile, two fore and one to the rear. The forward mounts were located just behind the wings and consist of pins projecting from the body of the missile. The rear pin provided lateral restraint, a further forward mount was designed by GAF to help stabilise the missile during rough cross-country travel experienced in Australia. The pins were designed to be strong enough to allow the missile to undergo the 180-degree swing from hull to the deployment position but weak enough to offer little resistance if the missile fired and they were still accidentally in place.

Rig 3

Once the second rig had completed its trials, the third and final rig was to begin testing. This would have had a full crew and be fully armored to the levels required of it when coupled with Centurion. Engine, tracks, suspension, fuel capacity and width were to be the same as Centurion Mk 7, with the length and height to be the minimum possible.

Malkara missiles mounted on a Humber Hornet at the Bovington Tank Museum. The blue on the warhead indicates that this was a practice round. Source: User growler2ndrow on Flickr.
The third rig was to be as close as possible to the real thing. The engine was to be mounted at the front with the louvers and decks moved over. Towards the rear was a large raised superstructure, heavily armored and able to stop any Soviet return fire with 8 inches (212 mm) at 45° for 300 mm effective plate over the front of the superstructure. The lower nose plate was 4 inches 101 mm at 45° for 142 mm effective armor. Upper hull front was 6.5 inches at 50° for 256 mm of armor. Sides were just 2 inches (50 mm) at 12° with the upper sides and rear at 17 mm and 12 mm respectively. 6 mm skirting plates were attached as standard.

Conclusion

The project stopped due to two main issues. The first was that Malkara was a bit of a black sheep in the missile family,
Then, as now, politicians tried to find faults in projects that they had little influence over, and rival firms with strong bonds were able to put a lot of influence over these men. Secondly, the project had moved back to the UK and despite several attempts to run demonstrations at Kirkcudbright, on each occasion the demonstration was put off due to bad weather and strong winds, and each time new invitations were sent out less people would respond. The media then waded in and highlighted issues which were duly unfair or outrightly not true but public opinion and support had gone.
With newer projects and firms, notably Vickers, putting more pressure on the government to support their new missiles, like the Vickers Vigilant, the end of Malkara seemed certain. Those in service were instead used on Humber Hornet as mobile air portable heavy anti-tank units in the Parachute Squadron, Royal Armoured Corps which came into existence on 3 February 1965, raised from cadres of Cyclops Squadron 2nd Royal Tank Regiment and The Special Reconnaissance Squadron (SRS). Malkara, however, was not quite finished. The Australians redesigned and altered the bits they had and ended up with the Ikara ship-borne long-range anti-submarine guided weapon that was developed for the Royal Australian Navy.
The Royal Navy had also shown interest in Malkara and a close-range anti-ship missile and although it was never taken in for direct service, it did end up forming the basis of the Sea Cat missile after Short Brothers of Belfast converted it over.

Malkara missile during testing in South Australia, at the Woomera Rocket Range in 1959. The flare on one of the fins, that was used for aiming, is visible on the lowest fin. Source: https://guides.naa.gov.au/

All Details for Malkara Unless Stated Otherwise

Malkara specifications

Project J Max range 2000 yards
Malkara Max range 1500 yards Mk I and 4000 yards Mk2
Malkara min practical range 400-500 both Mks
Project J min range 300 meters
Max direct fire unguided (loss of controls) 1000 meters
Boost acceleration 22g
Boost duration 0.6 secs
Sustainer duration 25 to 4000 yards
Velocity during sustained flight 137 m/s
Roll stabilized 2 pairs of wings
Control type Command Cartesian
No of wire cores 4 cores (2 on service model)
Control type of signal Shaped D.C.
Launch angle 3.5° above LOS target
Fuse type Eclectically operated
Fuse arming distance 250 yds
Arming delay 2 secs
Power type thermal batteries
Ground equipment sight monocular x 10
Cone diameter 8”
Explosive weight 56 lbs
Chance of hit on stationery 75% at 500 m 95% at 3000 m on 2.3 m sq target
Chance of hit on moving target similar to above with 2.3×4.4 m at 4.5m/s crossing
Malkara Penetration 150 mm at 60 degrees equivalent
Project J Penetration about the same
Max angle of fire +20/- 10 degrees
Firing weight 189.5 lbs
½ cruise wt 172.5 lbs
Roll 0.450 lbs. ft. sec2
Pitch 15.7lbs. ft. sec2
Yaw 15.7lbs. ft. sec2
Malkara Length 77 inches
Project J length 75 inches
Wingspan 31 inches
Wing weight 3 lbs each
Rate of Fire 4 rpm
Lethal blast radius > 100 meters
For information about abbreviations check the Lexical Index

Illustration of the Mk. III FV4010.

Illustration of the Mk. V FV4010

Illustrations by Tank Encyclopedia’s own Bernard ‘Escodrion’ Baker. Paid for by our Patreon Campaign.

Categories
Cold War British Prototypes

Chimera 1984

United Kingdom (1984)
Self-Propelled Anti-Tank Gun – None built

Chimera was a British School of Tank Technology study design to develop a casemated Armoured Fighting Vehicle (AFV) that could make constructive use of the remaining, dated FV4201 Chieftain Tanks then still in service. It is worth noting that there are several ‘Chimeras’, the UK not being one to throw a good name away and recycled it for several other projects. For the sake of brevity, all reference to Chimera in this text will refer to the 1984 version.
The project was part of the British LAIC (Long Armour Infantry Course), formerly known as the Tank Technology course. It had been renamed due to the expanding mechanization meaning that infantry now had an equivalent need to understand the technical aspects of the equipment they were operating and officers were invited from various Commonwealth nations.
This particular Chimera began in 1984 as part of LAIC number 35 at the Armour School, part of the Royal Armoured Corps Centre at Bovington, Dorset. The course involved a study to find a cheap and effective way to make a Self-Propelled Anti-Tank Gun on the Chieftain chassis that was to utilize new armor and technology but still be cheaper to produce and operate than the new FV4030 Challenger 1 main battle tank that was entering service.

Design

The result was a casemated design; the turret was removed, the gun was built into the hull and traverse was done by moving the whole vehicle left or right, much in the same way as the Jagdpanzer IV or Jagdpanther late war German tank destroyers. This design concept has several pros and cons over conventional turreted tanks. It lowers the overall profile of the vehicle and allows the placing of heavier armor over the front of the vehicle increasing its survivability. It often allows a more powerful gun to be fitted, however, this comes at a cost of only being combat effective to targets approximately 45° in front of it and less able to defend itself against threats to its flank and rear like a turreted MBT. This type of vehicle is ideally used as an ‘ambush’ weapon: laying in wait in a concealed location then changing location as soon as it fires its gun to another preplanned position to avoid detection.
As mentioned above, aiming was done by steering the vehicle to the left or right should the target be out of the vehicle’s primary arc of fire and therefore such machines are particularly vulnerable if the tracks are damaged. Having to start the tank’s engine and move the whole vehicle to bring the gun into position to fire on an enemy vehicle can reveal its position. This is not ideal. As the Germans found out in the Second World War, if used as a defensive vehicle they can excel, however, it’s their unsuitability for offensive deployment that highlights their greatest flaws. Used in place of conventional tanks, they will inevitably struggle against anything not approaching head-on. Finally, as a side note, they tend to be very long which can cause logistics issues and maneuvering issues around bends or corners.
The overall hull of the Chieftain was lengthened and an extra road wheel added to help take the weight of the Chobham frontal armour which was to be twice that of Challenger 1. It also helped to move the centre of gravity more to the centre. One issue found by the Germans and the Russians, particularly in the later heavily armored casemated vehicles, was that the extra frontal weight put undue stress on the forward suspension often resulting in them having steel road wheels at the front. By increasing the overall length of the hull, it helped to alleviate this somewhat.
The weapon was initially designed around the L11 120 mm rifled cannon gun with the early 1980s muzzle reference system mirror and shroud above the muzzle. This is sometimes marked up as the XL30 120 mm gun which was a considerably more powerful 120mm piece originally designed for the MBT-80 MBT. The XL30 also had the advantage of being shorter yet more powerful than the L11 and could use either the old ammunition or the new CHARM rounds entering service.
The frontal armor was incredibly thick for its time. It was 610 mm to 700 mm of Chobham armor on the upper half of the glacis angled at 20° or the equivalent of about 1400 mm of conventional Rolled Homogeneous Armor (RHA), yet considerably lighter at 2141 kg per ‘cheek’. The lower front of the vehicle was 110 mm of steel at 34° for 132 mm effective frontal plate, enough to stop cannon fire and older Soviet era 100 mm rounds at a distance but vulnerable to more modern rounds. It was envisioned such a vehicle would be deployed hull down ideally, therefore the lower plate would be out of sight and could not be targeted.
The roof section or slope leading up to the midway point was also conventional steel but 122 mm of it angled back at 80° for nearly 700 mm effective armor. The side armor was split between very thick on the upper half and thin on the lower half. Above the track line it was 310 mm thick along the sides for the first 50% of the hull and then dropped to 40 mm for the latter half. The lower side armor remained the same as Chieftain at 40 mm. The rear, back deck and bottom were 25 mm each. Two ‘bazooka’ plates protected the tracks along the sides and these were overlaid with 30 mm applique layers over the first 2/3 of either flank. The total armor weight for the vehicle was 32.5 tons.
Power was supplied by a late model L60 multifuel engine, likely to have been the 12A/N model (formerly known as 14A), giving at 750bhp. By this time, many of the older issues with the L60 had been rectified and although still somewhat temperamental its performance had increased dramatically over the earlier engines. It was also proposed to fit the Rolls Royce MBT-80 engine in this vehicle, replacing the L60. The MBT-80 engine was a 1500 hp unit able to squeeze 2000 hp when required (a less ambitious version of 1200-1500 hp ended up in the Challenger).
The crew was to consist of four men: the commander and gunner on the right hand side; the driver and loader on the left hand side. Both commander and loader have their own hatches which double as entry exit for the gunner and driver who does not have a conventional hatch. Optics were provided by 4 episcopes for the commander and 5 for the loader, the gunner had his own day/night thermal system. Close protection was given by a 0.5″ heavy machine gun remote weapon station located either over the main gun or to the side of the loaders hatch.

A handmade drawing of the Chimera 1984 tank destroyer, made in 1984. It closely matches drawings from official documents and is probably an original piece relating to the project – Source: Army.ca

Conclusion

The vehicle was built up as far as a large model and presented before a board of MOD and UK leading tank experts in 1985, where it was viewed as successful in achieving the targets set and the project was effectively filed away. No orders were given for modifications to start on the remaining FV4201 Chieftain Tanks still in British Army service. A similar but later design for a casmated Chieftain known as the Combat Test Rig or CTR and erroneously as the Jagdchieftain had also been carried out. However, that was part of the FMBT-70 program and unrelated to this project.

Side note: Tank versus tank

Tank Versus Tank: The Illustrated Story of Armoured Battlefield Conflict in the Twentieth Century is a 1988 book by Kenneth Macksey. It covers tank construction, development, technology, tactics and strategy from the first appearance of the tank on the battlefield up to the Yom Kippur War in 1973. The last chapter of the book deals with a “What-if scenario”, seeing an invasion of NATO by the Warsaw Pact somewhere in Central Europe. For this, Macksey presents the Goliath, an ‘assumed’ advanced tank destroyer used by NATO forces. However, the images presented are of the Chimera 1984 tank destroyer! The Goliath-Chimera is described as being able to reliably survive a frontal hit from the latest Soviet APFSDS rounds while taking out the latest Soviet MBTs at more than 1000 m. This is one of the few cases of a fake ‘fake tank’ in AFV history.

A 1990s battlefield envisioned. The NATO forces are on the left, with the Goliath-Chimera tank destroyer in the small village. Source: Tank versus Tank

Side view of the Goliath-Chimera tank destroyer. Source: Tank versus Tank

Beautiful illustration showing the Goliath tank destroyer in combat. Source: Tank versus Tank

A 3D model of the Chimera tank destroyer, probably done by a private modeller. Source – Quora

Specifications

Armament 120 mm XL30
Armor Front Armor: 610-700 mm of Chobham armor (1400mm RHA equivalent)
Crew 4 (driver, commander, gunner, loader)
Propulsion Late model L60 multi fuel engine (likely the 12A/N model developing 750 bhp)
Total production None built

Sources

CHIMERA: School of Tank Technology
LAIC: Armour magazine
Kenneth Macksey, Tank Versus Tank: The Illustrated Story of Armoured Battlefield Conflict in the Twentieth Century


The 1984 Chimera tank destroyer in NATO colors. Illustrated by Jaroslaw “Jarja” Janas, paid for with funds from our Patreon campaign.

Categories
Cold War British Prototypes

Excalibur Light Airborne Tank Destroyer

United Kingdom (1960)
Light tank destroyer – None built

School of Tank Thought

The Excalibur was a British light airborne tank destroyer designed at the School of Tank Technology in the 1960’s. The project called for a machine that weighed not more than 30 tons, was able to fit inside a Royal Air Force (RAF) Blackburn B-101 Beverley heavy transport aircraft and was fully amphibious. The vehicle was to have excellent mobility, mount a weapon capable of destroying any Soviet tank of the period and offer as low a profile as possible. During this period, the primary threat to NATO was the Warsaw Pact (composed of the USSR and its satellites) and, more importantly, it’s vast tank formations which were massed along the East German border. Many vehicles studied or designed in the School of Tank Technology during the 1960s focused on manoeuvre and destroy tactics with rapid reaction airborne vehicles being sought after to plug the expected Soviet breakout tactics.

Blackburn B-101 Beverley heavy transport aircraft. The Excalibur was meant to fit inside it.

Legendary Name

This vehicle is named after the legendary sword of the mythical English King, Arthur. It was the sword the King “pulled from the stone”, although different versions of the Arthurian Legend say it was given to him by The Lady of the Lake. The legend has it that after the death of the mythical King, it was thrown back into to the Lake from where it came, with the Lady retrieving it.

Design

To this end, the designers chose to go with a quite unusual configuration. Rather than choose the standard casemated layout that many opted for in this time period, the engineers chose to mount a semi-rotating turret on the front of the tank chassis to allow for maximum gun traverse whilst keeping a relatively low profile. This design overcame several core problems with casemated designs, notably their weakness to immobilizing factors. Casemated or turretless tanks with the gun mounted in a frontal superstructure rely on their tracks to pivot and make adjustments before firing. Any damage or terrain that prevents this effectively neutralises the vehicle’s offensive ability as their gun traverse is often very poor once immobile. By having a front mounted turret with 45° arc of fire to either side, the Excalibur overcame this problem as it no longer needed to rely on hull adjustments to bring its weapons to bear and this, in turn, would help to lower its overall signature and thus increase it survivability.
In order to keep combat weight down to meet the criteria of fitting and being transported in the Beverley aircraft, the developers went with a light aluminium armor layout. The hull front and turret superstructure were 50 mm of well-angled armor tapering down to 40mm on the lower front plate. The superstructure is 25 mm and 15 mm at the rear. The sides of the vehicle have several stowage boxes built in and a 5 mm separate backing plate remained behind this spaced plate.
Aluminium armor was chosen as it is light enough for making airborne tanks but strong enough to stop what was required in the design specs, notably artillery fragments and machine gun fire. The notion of having a light vehicle with RHA levels of armor to stop APDS rounds and guided missiles of the period was out of the question. Excalibur survivability would come from agility and ambush tactics.
Several weapons were considered in the design but a 105 mm low-pressure gun was chosen. Low-pressure weapons were built to fit onto platforms or chassis that require a large caliber but cannot handle the high recoil pressures or have space for a long recoil. Whilst not ideally used for conventional Kinetic Energy rounds, they work very well with HEAT (High Explosive Anti-Tank) and HESH (High Explosive Squash Head) rounds that require lower velocities on impacting to work effectively. In fact, due to the way they work, the rounds are often better than the high-pressure version as they require less casing meaning increased HE filler. Low-pressure guns do require the gunner to compensate the large drop of the shell over larger distances in order to hit far-away targets. The range of such a weapon is also significantly smaller than that of a high-pressure gun. Although recoilless rifles have similar performance to low-pressure guns in terms of velocity, they are unsuitable for any vehicle with an enclosed space, such as Excalibur. Close protection was provided by a pintle mounted heavy machine gun and a coaxial pair consisting of a 0.5 (12.7 mm) and a 0.3 (7.62 mm) machine guns.
Despite the front mounted weapons, the center of gravity was fairly good and the weight at the nose end not excessive due to the use of aluminium armor and the fact that low-pressure guns are much lighter than their high-velocity counterparts.


Swingfire missile. The Excalibur was meant to be able to mount eight such missiles for AT duties.
Excalibur could also come fitted with Swingfire missiles in the main body. If required, these would be in a series of bins mounted in the boxy body above the tracks. With Swingfire’s ability to change its course by 90° in the first second of firing (something no other ATGM has been able to emulate), it would allow the Excalibur to fire from a defiladed position (behind a hill or ridge exposing little if any of the vehicle) knocking out any tank with its 800 mm of penetration but these fittings were an optional extra. A later series of designs drawn up to a General Staff Operational Requirement (GSOR 1006) had the Swingfires mounted in several positions including along the sides and top racks. Other guns were also considered, from 76.2 mm pieces with drum fed magazines and long HV 105 mm or even 120 mm weapons.
Power was provided by a Leyland L50 multi fuel two stroke 580 bhp engine that ran on diesel or MT80 petrol delivering a top road speed of 48 mph (77 km/h) via an Allison XTG 411-3 automatic transmission with a road range of 318 miles (611.5 km). Suspension was torsion type and the running gear consisted of 5 pairs of double road wheels with the 22 inch (55.8 cm) rubber, brushed steel tracks supported by four return rollers. The engine also had one more feature; it had a built-in waterjet system. This allowed the Excalibur to cross large bodies of water relatively quickly as the whole system required no preparation being inherently amphibious.
The crew of three were all based in the turret at the front, the commander and gunner to the right and loader/radio operator to the left. The gunner doubled up as the driver as the Excalibur was never designed to shoot on the move and the whole system could be switched from gunner to mobility mode at the flick of a switch.

Just a Peculiar Idea

The Excalibur itself was never built however the GSOR 1006 project did see the plans dusted off and further designs drawn up for a service vehicle. However, this too never entered service.

Shrivenham, one of the places where the School of Tank Technology was based.

Excalibur specifications

Dimensions 25.10 x 8.11 x 11 ft
(7.6 x 2.47 x 3.3 m)
Total weight, battle ready 60,000 lbs (30 tons) max
Crew 3 (commander, gunner/driver, loader/radio operator)
Propulsion Leyland L50 multi fuel two stroke 580 bhp
Transmission Allison XTG 411-3
Suspension Torsion bars
Steering T-bar mechanism
Speed 48 mph (77 km/h)
Ground clearance 16 in (40.6 cm)
Track 22 inch (55.8 cm) rubber, brushed steel
Armament 105 mm low pressure gun
2 x 7.62mm machine guns
12.7mm HMG
Optional: 8 x Swingfire missiles
For information about abbreviations check the Lexical Index

Sources

School of Tank Technology (STT) Excalibur, British National Archives


The Excalibur Light Tank Destroyer. The unusual front turret is clearly visible. Illustrated by Bernard “Escodrion” Baker. Illustration paid for thanks to Patreon donations.

Categories
Cold War British Prototypes Cold War Canadian prototypes Coldwar American Prototypes

FV4201 Chieftain/90mm Gun Tank T95 Hybrid

USA/UK/Canada (1957-59)
Main Battle Tank – none built

ABC Countries

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

Guns

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

Medium tank guns

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

Armor

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

The Canadian Intervention

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

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

Conclusion and one last hybrid

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

T95/FV4201 hybrid (T95 with FV4201 turret) specifications

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

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

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

Links, Resources & Further Reading

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


T95 hull with XM60 Turret and standard 90mm Gun.


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


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


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


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

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

Categories
Cold War British Prototypes

FV4005 Stage I & II

United Kingdom (1950-56)
Anti-tank SPG prototype – 2 built

In the early 1950s, the opening years of the Cold War, the western powers were highly concerned with the amount of powerful armor available to the USSR.
In answer to this, the British military developed a ferocious new anti-tank gun, the 183 mm (7.2 in) L4. The race was on to find a suitable mount for this monstrous weapon. It was first proposed to be used as part of the FV215 project. This self-propelled gun (SPG) design was based on the FV200 Universal tank concept. This vehicle, however, did not go further than the mock-up stage.
Designers tried again, this time with a proposal to mount the gun on the chassis of Britain’s trusty new Main Battle Tank, the Centurion. This vehicle would go under the project title of FV4005.

Original blueprint on the FV4005 Stage II – Photo: Andrew Hills/Ed Francis

Design and Development

The FV4005 was a separate project from the Centurion based vehicle, the FV4004 Conway, armed with the 120 mm (4.72 in) L1 gun. The two projects were not related but had the same goals. The FV4005 was fitted with a much larger gun.
Vickers-Armstrong was in charge of the development of the tank. The Centurion chassis chosen for the project was that of the Mk.III. The platform for the gun was made to fit perfectly into the existing turret ring of the hull. Only slight alterations were made to the chassis. A large recoil spade was added to the rear of the vehicle and an equally large travel lock, or “Gun-Crutch” as the British called it, was added to the front.
The recoil spade helped to keep the vehicle in place while firing, meaning the gunner didn’t have to re-adjust after every shot. The travel lock was used to keep the gun from swaying while the vehicle was moving, helping to reduce stress on its components.

Britain’s Biggest Boom-Stick, the 183mm L4

In 1950, work started on the Ordnance Quick Firing 183 mm (7.2 in) L4 gun. At the time, it was the largest and most powerful tank gun in the world. The cannon was based on the 183 mm (7.2 in) BL 7.2 inch howitzer, a WWI era weapon. The gun itself weighed a mighty 4 tons and when fired it produced the equivalent of 87 tons of recoil force.
The L4 was designed to be chambered for only one type of ammunition, HESH (High Explosive Squashed Head). It was separately loading ammunition. The projectile was loaded first followed by the correct propulsion cartridge. Each shell weighed a combined total of 104.8 kg (231 lbs). A shell of this size understandably produced a substantial amount of fumes and smoke inside of the fighting compartment. As such, a large fume extractor was added to the barrel, a relatively new feature at the time.
The 183 mm was tested in live fire trials against a Centurion and a Conqueror. In 2 shots, the 183 blew the turret clean off the Centurion and split the mantlet of the Conqueror in half. In total, the gun fired 150 shells.

Stage I

The FV4005 Stage I was a relatively simplistic vehicle, serving as little more than a test-bed for the 183 mm L4 gun. The hull of a Mk.III Centurion tank was chosen for the project. The gun was mounted on a platform in the turret ring, completely open to the elements devoid of any armor.

The Stage I, possibly in Workshop 5 (the so-called secret shed at Elswick) – Photo: warspot.ru
The L4 was expected to have a rate of fire of 6 rounds per minute. As mentioned above, the separately loading 183mm HESH ammunition equipped to the FV4005 weighed a combined total of 104.8 kg (231 lbs) each. As such, the gun would require 2 loaders to service the weapon effectively. 6 rounds a minute would still be a hopeless fantasy, however.
To combat this, in an attempt to ease and quicken the loading process, Vickers-Armstrongs developed a mechanized ammunition feed system, similar to that used on the 104-mm Green Mace anti-aircraft gun. Contrary to popular belief, this was not a traditional auto-loader. It was simply a loading assistance device that would help to align the shells and propellant with the breach. The mechanism did not include a rammer.*
Testing highlighted stability issues with the platform when the gun was fired. It was also surmised that the open, unarmored fighting compartment, necessitated by the loading-system, was not worth the price in crew safety. As such, work began on re-working the gun platform.

The Stage I during trials – Photo: Ed Francis
*It should be noted that exact details of whether the Stage I used an auto-loader is a gray area. As such, portions of information are missing from this segment concerning the vehicles weapon. In the not too distant future, we hope to shed light on these areas.

Links, Resources & Further Reading

Ed Francis
Archives, The Tank Museum, Bovington, England
Key Publishing Ltd., The Big Gun Centurions, Classic Military Vehicles. Written by David Fletcher.
An article on the FV4005 by Yuri Pasholok on warspot.ru (Russian)

Stage II

The FV4005 Stage II was the final form of the project. It was designed and built in 1955. The open gun platform was replaced with a large, box-like turret. The loading assistance device was also deleted, in favor of more traditional loading. With the addition of the large, approximately 2-meter high turret, the FV4005 weight climbed to 50 tons.

The FV4005 during trials in 1956. Note the driver in the hull, and the commander at the very top of the turret. Photo: warspot.ru
Despite being an extremely prominent target, the turret armor was only 14 mm (0.55 in) at its thickest. This was easily penetrable even by large caliber machine guns rounds. It also only had enough space to store 12 rounds. These rounds were stored in racks of 6 on each side of the large bustle.
The turret housed 4 crew members. These were the commander on the forward left, gunner on the front right and 2 loaders positioned behind the gun. On the left of the gun, in a small box on the cheek, was a coaxial .30 cal (7.62 mm) machine gun. This was most likely used for ranging rather offensive/defensive fire. There was a large door in the rear of the turret bustle for crew access and ammunition re-supply. The driver was located in the standard position in the hull.
It should be noted that the lack of armor was intentional. This vehicle was designed to engage at long-range, shoot and re-position. Flexibility was slightly hampered by the turret, however. In theory, it was fully traversable. On uneven ground, this was not recommended due to balancing issues with the gun. As such, the vehicle only really had a 90 degrees arc of fire to the left and right.

The Stage II turret being towed to firing trials – Photo: Ed Francis
A rear view of the vehicle. Note the recoil spade and the box above it. This box holds the winch to raise and lower the spade - Photo: Ed Francis
A rear view of the vehicle. Note the recoil spade and the box above it. This box holds the winch to raise and lower the spade – Photo: Ed Francis

A rear view of the turret showing the rear door open in a display of how ammunition is loaded into the vehicle – Photo: Ed Francis

Fate

January 1957 marked the end of the road for the 183 mm armed SPGs, despite admirable performance during trials. The intended role of the vehicles had been overtaken by increasing development of ATGMs (Anti-Tank Guided Missiles). These granted the same, if not better, anti-armor capabilities, with the experiments ultimately culminating in the Malkara and Orange William missile systems.
Work would continue on the gun. Had it have been adopted, the L4 would’ve been succeeded by the 180mm “Lily White”. This only got as far as conceptual stages, however.
The FV4005 Stage II is the only one of these 183mm armed vehicles to survive to this day. The turret is original, but it was mounted on a spare Mk.VIII Centurion hull, not the original it was trialed with. It is missing the recoil spade and travel lock. This “Cut-and-Shunt” representation of the vehicle now sits as a “gate-guardian” at The Tank Museum, Bovington, alongside an M4 Sherman. Its predecessor, the FV4004 Conway is safe and sound in the VCC (Vehicle Conservation Center) at the site.

The 4005 as it stands today out side the Bovington Tank Museum – Photo: warspot.ru

An article by Mark Nash

FV4005 Stage II Specifications

Dimensions (L-W-H) 7.82 (without gun) x 3.39  x 3.6 m
(25’7″ x 11’1″ x 11’8”)
Total weight 50 tons
Crew 5 (driver, gunner, commander, x2 loaders)
Propulsion Rolls-Royce Meteor; 5-speed Merrit-Brown Z51R Mk. F gearbox 650 hp (480 kW), later BL 60, 695 bhp
Speed (road) Apx. 30 km/h (19 mph)
Armament QF 183 mm (7.2 in) L4 Tank Gun
.30 Cal. (7.62 mm) machine gun.
Armor 120 mm frontal hull armor. Turret 14mm all over.


Tank Encyclopedia’s own illustration of the FV4005 Stage II by David Bocquelet