Categories
Cold War Belgian Prototypes

M41 LCTS 90

Belgium (1992)
Light Tank – 1 built

At the end of WW2, the US Army was using the 75 mm M6 gun-armed M24 Chaffee light tank, an otherwise satisfactory and reliable light tank. Nonetheless, by 1949, the US Army had decided to replace it, leading to the T41E1 and, which was eventually type classified as the M41. Fitted with the more powerful M32 76 mm main gun, gun stabilization (the British Vickers system), and a rangefinder, the M41 marked a step-change in the firepower of light tanks for US forces. Weighing just 23.5 tonnes (nearly 6 tonnes more than the Chaffee), the M41, powered by a Continental or Lycoming boxer 6 cylinder engine delivering 500 hp, was an agile tank with excellent firepower for its weight. Widely exported, it saw decades of use in dozens of armies around the world, but by the 1990s was seriously obsolete. An inadequate fire control system, no laser range finder, and a gun incapable of tackling even second-line Soviet tanks meant the M41 had had its day. Like other light tanks of WW2 or post-WW2 era, it was simply not able to offer a modern army what was needed in terms of firepower. Whereas particularly Western armies could afford the development of a new era of light, capable, and well-armed platforms offering increased protection, second-rate armies could not. Many armies around the world were still operating or had vehicles like the M41 or AMX-13 in stock or were looking to perhaps add some capability to their armored forces by adding a turret to an APC like the M113

The Belgian firm of Cockerill, with a very long history of development and manufacture, offered exactly this option in the early 1990s in the form of a light turret with a new powerful 90 mm gun, offering performance similar to the well-regarded Royal Ordnance 105 mm gun but without the weight. This option, therefore, potentially allowed more cash-strapped militaries to upgrade otherwise obsolete vehicles to modern firepower standards or to add much-needed firepower to an APC or wheeled platform. For the purpose of tests and to potentially elicit sales, this new turret, known as the LCTS, was mounted on a surplus M41 Walker Bulldog, presumably from surplus Belgian stocks as the Belgian Army had operated 135 of them between 1958 and 1974. Despite the potential benefits on offer, this turret did not find any interest in itself, but its descendants are currently in service with the US Army and other forces around the world.

Design

The Hull

The M41 light tank was of a conventional layout, with the driver in the front, crew space in the central part, and engine in the rear. The turret was mounted roughly centrally on the vehicle and the new LCTS turret was mounted in exactly the same place as the original. The available photograph clearly shows the use of a turret-ring adapter mounted on the hull to match the new turret.

The Crew

Only a single crew member was used in the hull of the M41 light tank and this crew member, the driver, was obviously retained for this demonstrator vehicle too. Sat in the front left of the hull, the driver, his controls, hatches, optics, etcetera would remain unchanged from the M41 or other platform on which the turret could be placed, notwithstanding any additional upgrading done at the same time as adding the turret. The previous crew complement of the M41 consisted of three more men, with the commander, gunner, and loader in the turret but, for this vehicle, that original turret was completely removed and so were these crew positions.

Inside the new turret was space for just two crew, seated roughly side by side. The first, the commander, sat on the left of the turret under a single-piece hatch. He was provided with a single forward-facing sight for the primary weapon and had 5 periscopes around his hatch for observations. Any additional sights, including a thermal sight, were presumably available as aftermarket options for potential buyers.

The second crew member in the turret was the gunner and he sat on the right of the turret, also with a single one-piece hatch. He too had a single primary forward-facing sight for the main gun and an array of 5 periscopes around his hatch for all-round observations. With no loader in the turret, the gunner would have to fulfill this function too, but it allowed for a substantially smaller turret as well, which was a substantial size and weight tradeoff for a reduced rate of fire available.

Automotive

The M41 tank used a 6 cylinder Boxer-type petrol engine from either Continental or Lycoming AOS 895-3 delivering 500 hp at 2,800 rpm. This allowed the 23.5-tonne tank to reach speeds of up to 45 mph (72.4 km/h) on a road. Later versions of the M41, the M41A1, and M41A2 used a fuel-injected version of this engine, the AOSi-895-5.

The suspension was provided by means of 5 double road wheels with rubber tires and 3 rubber-tired return rollers, all running on tracks 21 inches (533 mm) wide. The CD 500-3 cross drive transmission was at the back driving the sprocket to move the tracks and a single idler wheel was located at the front. There is no information in Janes, from Cockerill, or from the photograph of the vehicle available to suggest any changes to the hull used. Any upgrade program from a buyer may obviously have included upgrades to whatever power plant or drive desired. The available photograph of the vehicle from Janes does show some reel on the back deck of the hull, but this does not appear to have any relevance to the design or automotive elements.

90 mm armed LCTS turret on the hull of an M41 light tank. Source: Janes

The Turret

The turret was the whole point of the design. Able to be fitted to a variety of hulls, it was only fitted to the chassis of an M41 light tank for demonstration purposes. Using this hull was a clear sign of the potential market for a turret that could modernize existing light tanks, such as the M41 or AMX-13, which were still in widespread international service but which were otherwise obsolete. Adding this turret would offer potential clients a relatively cost-effective way to make an old platform into a capable modern vehicle without the expenditures needed to develop or purchase a completely new vehicle.

Firepower

The LCTS turret was fitted with a pair of 7.62 mm machine guns of a type not specified, as these would be changeable by the client. One of the machine guns was fitted coaxially with the main gun and the other would be mounted on the roof of the turret for anti-aircraft protection. Up to 750 rounds of 7.62 mm ammunition could be carried in the turret.

The main armament, however, was not changeable like the machine guns, as it was inherent to the design. Consisting of the 90 mm Cockerill Mk. 7 gun, this was mounted centrally in the narrow front of the turret. The gun was able to be rotated a full 360 degrees and was capable of -9 to +20 degrees of vertical movement. Turret traverse was powered and the speed of rotation was 30 degrees per second. This meant it would take 12 seconds to make a single full 360-degree revolution.

Two banks of four smoke grenades were carried on each side of the turret. Eight additional grenades were carried inside the turret. Up to 12 rounds of 90 mm ammunition could be carried in the turret, as well as some additional rounds in the hull of the tank, although this would depend on what the donor hull being used would be. For example, mounting the turret on an M113 would allow significantly more potential stowage than on an AMX-13 hull, so the exact stowage could not be determined. It is worth noting that the gun and turret, during various iterations, were trialed for several vehicles, including the British Saladin armored car at one point. Stowage on the M41 for its original 76 mm gun was 57 rounds with 13 in the turret, 11 in a ready rack, and 33 in the hull. For this new smaller turret, just 12 90 mm rounds were able to be carried in the turret and, assuming a substantially smaller or no space for a ready rack, this would still leave hull stowage for around 30 rounds in the hull. In total, therefore, perhaps around 40-45 rounds could be stowed using this turret on a modified M41.

The 90 mm Cockerill gun (also sold as the 90/46 KEnerga by MECAR), launched in around 1982, went through various stages of development. The Mk. 7 was a modification of the Mk. 6 and was itself modified and replaced by the Mk. 8 in 1992. Weighing less than ¾ of a tonne and with a length of 4.365 m (L/48.5), the 90 mm Cockerill operated at a pressure of just 310 MPa and produced a recoil stroke of just 350 to 370 mm.

Ammunition for the Cockerill gun was made by MECAR and included a potent Armor-Piercing Fin-Stabilised Discarding Sabot – Tracer (APFSDS-T) round with a muzzle velocity of 1,500 m/s able to defeat NATO triple heavy targets, High Explosive Plastic (HEP) to defeat bunkers, structures, light armor and also for indirect fire use, smoke, canister, High Explosive Anti-Tank (HEAT), and training rounds.

Armor

The hull armor for the M41, as would be expected from a light tank, was poor, with just 30 mm at 40 deg. on the front, 25 mm on the sides, and 20 mm at 40 deg. on the rear. The new LCTS turret was basic and based on a simple welded steel shell. The basic shell provided protection from small arms fire and could, if required, be supplemented with some additional layers bolted to the exterior to increase protection. This would also increase the weight from 2,400 kg and the ballistic protection improvements would not be sufficient to resist enemy tank fire and would only go as far as providing protection from heavy machine-gun fire. More than that would be somewhat pointless, given that the prospective vehicle on which this would be mounted was relatively lightly armored too.

Conclusion

The LCTS turret was similar in size to the ACEC AK90E turret as fitted to the ACEC Cobra a few years prior. It too mounted a 90 mm gun and seated the two crew side by side. The AK90E turret was larger though, weighing some 200 kg more and able to stow 17 more 90 mm shells than the LCTS. Given that both firms are Belgian, and offered these very similar turrets just a few years apart, it is hard not to see the LCTS as a direct development from the AK90E both on a purely visual comparison but also based on the technical specifications of the two.

The LCTS 90 turret with the Cockerill Mk.7 gun mounted on the hull of a Belgian M41. Illustration by Ardhya “Vesp” Anargha, funded by our Patreon campaign

Comparison between ACEC AK90E and LCTS Turrets

ACEC AK90E LCTS
Crew 2 (Commander & Gunner) 2 (Commander & Gunner)
Main Armament 90 mm Cockerill Mk.7 or Mecar 90 mm KEnerga Cockerill 90 mm
90 mm Ammunition (turret stowage only) 29 12
Secondary Armament Coaxial 7.62 mm MG Coaxial and roof-mounted 7.62 mm MG
7.62 mm ammunition 750 rounds 750 rounds
Traverse Speed 28 deg./sec 30 deg./sec
Elevation Range -10 to +25 -9 to +20
Fire Control OIP LRS 5 incl. Thermal day/night sight and laser range finder unknown
Commander’s Optics 4 M17 observation periscopes 5 periscopes plus gun sight
Gunner’s Optics 4 M17 observation periscopes 5 periscopes plus gun sight

The LCTS, as shown, received no orders. It was undoubtedly a capable platform on which to mount the very capable 90 mm Cockerill gun and combined with some modern fire control and ranging would have provided a serious way to upgrade otherwise obsolete vehicles to a modern standard. Despite the lack of sales, Cockerill continued their development and refining and the descendant design of the LCTS 90 mm is the LCTS 90MP – a highly successful turret with a 90 mm gun in service, amongst others, with the US Army. 

ACEC AK90E turret. Source: Janes

M41 LCTS 90 specifications

Total weight M41 or other vehicle hull weight plus 2,400 kg (turret) as mounted on the M41 estimates ~23 tonnes
Crew 3 (commander, gunner, and driver)(assuming donor vehicle uses a single hull crewmember – commander and gunner in turret)
Engine 6 cylinder Boxer-type Continental or Lycoming AOS-895-3 petrol engine delivering 500 hp at 2,800 rpm or the AOSi-895-5 fuel injected version
Armor bulletproof – capable of being improved
Armament 90 mm Cockerill Mk.7 gun plus two 7.62 mm machine guns
Ammunition 12 x 90 mm rounds (turret) plus hull stowage, 750 7.62 mm rounds

Sources

MECAR. KEnerga 90/46 lightweight gun system advertisement.

MECAR 90 mm Mk.3/ Mk.8 ammunition at mecar.be

Foss, C. (1994). Janes Armour and Artillery. Janes Information Group

Cockerill (John cokerill Ltd.). Performance Tables for 90 mm Mk. 3 gun.

Icks, R. (1972). M103 Heavy tank and M41 Light Tank (Walker Bulldog). AFV Profile Weapons 41. Profile Publications, UK

One reply on “M41 LCTS 90”

Hey, your section title “Desing” should be spelled as ‘Design’. Thank you for this wonderful article, this is a tank I had never heard of before!

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