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Tuesday, April 12th 2011, 4:50am

French Tanks

The French Army was one of the first to field tanks in warfare, trailing only the British Army. In 1917 at the height of the Great War, France deployed the most successful tank of all time [1], the FT-17, which was copied by countries around the world, and remains in use in some countries to the present day.

Note [1]: At least, for our alternate history!

Light Tanks
- Char-6 Bruyere (AMX-13/75)

Medium/Cavalry Tanks
- Char-8 Montbrun (AMX-34)
- Char-13 Tigre (AMX-40)

Heavy/Infantry Tanks
- Char-2 Lefebvre (Transall FT-37)

French Army Tank Guns, 1940-1950
  • CN-75-45 (75mm/L45) - The tank mounting of the mle 1938 TAZ AT and AA gun. Used only on the Char-2E Lefebvre heavy tank.
  • CN-75-38 (75mm/L38) - A short-barreled, short-recoil version of the CN-75-45, this was developed for the Char-6A Bruyere. The design's recoil-dampening mechanisms were a source of problems, and the gun was replaced quickly by a CN-75-60 in an oscillating turret.
  • CN-75-53 (75mm/L53) - This 75mm/L53 tank gun was developed from the preceding CN-75-45 gun, which was itself a version of the mle 1938 TAZ anti-tank and anti-aircraft gun. The CN-75-40 was used in limited quantities on the Char-8A1 tank. The gun was quickly replaced by the longer-barreled F2 model on the Char-8A2.
  • CN-75-60 (75mm/L60) - A clean-sheet 75mm tank gun design. The most successful of the French 75mm AT guns. The gun came in a standard turret mounting and an oscillating turret with an auto-loader, which had a nine-round magazine. The autoloader in the oscillating turret had some teething troubles through early 1944, but nothing like the CN-90-54 M1 which was intended to replace it.
  • CN-90-54 M1 (90mm/L54) - A modified version of the 90mm anti-aircraft gun equipped with a five-round autoloader and installed in an oscillating turret for the Char-8A3. The autoloader proved extremely unreliable and the turret too cramped for crew efficiency, and so was withdrawn from service. The gun itself, without the troublesome autoloader, was later placed in the Char-13 tank as the CN-90-54 M2.
  • CN-82-70 (82mm/L70) - The CN-82 series gun was developed as the largest gun able to fit in a standard turret on the Char-8A3 Montbrun, intended to replace the unsuccessful CN-90-54 M1.
  • CN-90-54 (90mm/L54) - A re-designed CN-90-43 M1 without the autoloader, and with a bore evacuator installed.


Monday, April 25th 2011, 10:32pm

Transall FT-37

FT-37 / Char 2E “Lefebvre”
-- Length: 7.0 m
-- Width: 3.3 m
-- Height: 3.0 m
Weight: 45 metric tons
-- 1x 75mm/L45 gun
-- 1x Fusil-mitrailleur Modèle 1930 in turret
-- 1x 6.5mm MG in hull
Speed: 35 kph (22mph)
Engine: 600 hp diesel
Transmission: 2x4 forward, 1 reverse
Suspension: Torsion bar
-- Turret face: 120 mm (sloped equivalent)
-- Turret sides: 90mm
-- Glacis: 100 mm (sloped equivalent)
-- Sides: 80 mm
Constructors: Transall

Notes and History:
The FT-37 heavy tank was developed by the multinational Transall, which pitched the design to the members of the FAR Treaty Alliance; the tank design was eventually purchased by all three major powers (Russia as the TT-37, Atlantis as the AT-37, and France as the FT-37). The FT-37 demonstrated a wide variety of capabilities, with an excellent gun, outstanding armour, and exceptional mobility (at least for a heavy tank); as a result, the Lefebvre ended up becoming the standard French heavy tank for the next decade. The original design specified a capacious turret ring which proved to be highly fortuitous for up-gunning later in the 1940s. Approximately 248x tanks were ordered by France and delivered through the late 1930s, equipping the heavy tank regiments of the French Army. Despite regular proposals to up-gun the design to 90mm, slightly under half of the tanks were actually up-gunned before they were moved to the inactive reserve in 1943, being replaced by the more mobile but more lightly-armoured Char-8A3.


Tuesday, April 26th 2011, 6:51pm

Renault Char-6 Bruyere

Renault Char-6 Bruyere (Renault Bruyere Cavalry Tank)
Design of the Char-6 Bruyere light tank started as a collaboration between Renault and AMX (Atelier de Construction d'Issy-les-Moulineaux) during the late 1930s, operating under the oversight of DEFA's tank design group. In the late 1930s, French armour developers called for two different types of vehicle - a highly mobile, lightly-armoured tank, and a well-armed medium-weight cruiser tank. Responding to the request for a light tank, Renault and AMX initially drew up their own separate projects, known as the Renault 18t and the AMX 12t, to meet the French Army's light tank requirements. The Renault proposal featured a lightweight 75mm/L39 gun in a cast turret, while the AMX prototype had an autoloading 47mm gun in an oscillating turret. After initial trials, the newly-formed Armoured Cavalry Branch rejected the AMX 12t design due to its unreliable autoloading gun and oscillating turret, but similarly condemned the Renault 18t for its extremely poor mobility, attributed to an unreliable petrol engine and obsolete leaf-spring suspension system.

After the rejection of both designs, DEFA proposed that further development of the light tank be merged, with the hull of the AMX 12t to be enlarged in order to mount the turret of the Renault 18t. Since the two tanks had turet rings of similar size, this was accomplished with relative ease. A more reliable Renault-manufactured diesel engine was also prepared, as AMX's original powerplant, composed of two eight-cylinder engines mounted on the right side of the tank, proved unable to deal with the power requirements of the enlarged vehicle. The trailing idler wheel of the 12t, which proved a maintenance issue, was also replaced with a raised idler. In this configuration, the French Army declared itself satisfied with the joint project, and christened it the Char-6 Bruyere light tank.

Production started at Renault in 1941, with AMX serving as a primary parts constructor until December of 1942. Renault had some production difficulties during this time, being unable to reliably meet the French Army's production demands, and suffered some reliability issues with the twelve-cylinder diesel engine. These issues caused Renault to lose money on tank production through the end of 1942, at a time when they wished to concentrate more fully on the profitable and high-volume civilian automobile market.

In late 1942, AMX returned to the Armoured Cavalry Branch with a prototype variant which they had been developing. This variation resurrected the idea of an oscillating turret, but adopted the same 75mm/L60 gun used by the Char-8 Montbrun medium tank. AMX proposed a number of other major changes to to the hull to increase reliability and lower manufacturing costs. These upgrades could also be applied as a rebuild alternative to existing Bruyere light tanks. Although DEFA signed off on the proposed changes, Renault management believed the "D Series Upgrade" would drive up their own costs further, and elected to opt out of their production contract, focusing on production of civilian vehicles. AMX took over all production responsibilities. As AMX was also by then the primary constructor for the Char-8 medium tank, this move made the company the largest armoured vehicle manufacturer in France.

Starting in 1943, AMX began rebuilding Char-6A tanks with the new modification package, reclassifying them the Char-6D1 mle.1941 m.43. New vehicles, manufactured new to the same standard, were designated the Char-6D2. The adoption of the lighter oscillating turret and other space- and weight-saving components meant that, despite the increase in the Bruyere's firepower, the Char-6D weighed three and a half tons less than its predecessor.

The Bruyere was distinctly identifiable by its use of a rear-mounted turret, with the engine located forward, to the right of the driver's compartment. The oscillating turret also became a major identification factor. The autoloader for the 75mm/L60 gun was located in the turret bustle, and had two six-round magazines. This allowed twelve rounds to be fired off in short order; but after the magazines were expended, the tank was forced to withdraw so the crew could reload the magazines from outside the tank's hull. This proved to be the tank's principle weakness, particularly in the export market. The French Army, by contrast, did not see this as a particular problem, and developed a particular preference for oscillating turrets with autoloading guns.

The Bruyere's combination of light weight, low cost, heavy firepower, and outstanding mobility made the vehicle a success on the export market. Bruyeres were sold to the Indochinese Army, the Philippines, Chile, Greece, Bulgaria, and Siam.

Specifications: Char-6A mle.1941 (R18/75)
-- Length: 6.5m (hull and gun); 5m (hull)
-- Width: 2.6m
-- Height: 2.4m
Weight: 18 tons
-- 75mm/L40
-- One 6.5mm GPMG
Speed: 55kph (road), 25-30kph (cross-country)
Engine: Renault V12 diesel, 22.4L, 342hp
Power/Weight Ratio: 19 hp/ton
Transmission: Manual
Suspension: Torsion bar with five road wheels and two return rollers
-- Turret face: 40mm
-- Glacis: 40mm
-- Sides: 15mm
Constructors: Renault (primary), AMX, Hotchkiss

Specifications: Char-6D mle.1943 (AMX-13/75)
-- Length: 6.5m (hull and gun); 5m (hull)
-- Width: 2.6m
-- Height: 2.4m
Weight: 14.5 tons
-- 75mm/L60 in oscillating turret
-- One 6.5mm GPMG
Speed: 60 km/h (road), 25-30kph (cross-country)
Engine: Alsthom V6 MD.6/20 diesel, 20L, 320hp
Power/Weight Ratio: 22 hp/ton (Char-6D2)
Range: 400 km
Transmission: Manual
Suspension: Torsion bar with five road wheels and two return rollers
-- Turret face: 40mm
-- Glacis: 40mm
-- Sides: 15mm
Constructors: AMX

The Bruyere chassis was designed with consideration for manufacturing offshoot variants, which include:
- Char-6A Bruyere: Standard (base) vehicle.
- Char-6B Bruyere: Otherwise standard Char-6A fitted with a 105mm/L17 howitzer in a turret (the same as the CDA-6 assault gun).
- Char-6D Bruyere: Char-6A fitted with the automatic oscillating turret.
- AMR-6 Bruyere: Tank specially fitted out for reconnaissance duties; used the FL-11 oscillating turret manufactured for the Panhard EBR. Otherwise easily confused with a regular Char-6 Bruyere.
- CDA-6 Sorbier: An assault gun equipped with a 105mm/L17 gun in a casemate.
- CA-6A, B Lauriston: A self-propelled gun equipped with a 75mm howitzer (CA-6A) or a 105mm howitzer (CA-6B).
- CDC-6 Lariboisiere: A tank destroyer equipped with a 75mm/L53 AT gun in a casemate.
- VBG-6A, B Bertrand: An armoured engineering vehicle with a dozer blade, digger, and 80mm demolition gun (VBG-6A), or a winch and crane for vehicle recovery (VBG-6B).
- PP-6 Bertrand: An armoured engineering vehicle equipped with a single-piece seven-meter bridge with a weight limit of 20 tons.
- VD-6A, B Bertrand: An armoured engineering vehicle (similar to the VBG-6A) equipped with a mine-flail (VD-6A) or mine rollers (VD-6B).
- DCA-6 Tornade: An anti-aircraft tank equipped with two 25mm or one 40mm gun.
- VBE-6: A training tank version. No gun is provided and the armour, maintained for reasons of weight simulation, is made of softer metals not designed to stop projectiles.

The Char-6 has seen some export orders, with the primary customers to date being the Philippines and Bulgaria.


Friday, September 9th 2011, 3:51pm

SOMUA/AMX Char-8 "Montbrun"

Char-8 Montbrun (Montbrun Medium Tank or AMX-34)

The Montbrun's design history began in the 1930s, just prior to the beginning of the Rif-Atlas Revolt, as a result of the French Army's concern about the growth of Indian and German tank designs. At the time the Montbrun's development started in 1937, the French Army, in the form of the Commission de Vincennes, spearheaded by General Jean-Marie Lemaréchal, had formed very decided opinions about the sort of tank they wanted. Although the French had produced a number of innovative and technically impressive tanks through the early 1930s, procurement was an issue, with small production runs and various different types of tanks leading to a high average vehicle cost and issues with parts and supplies. Lemaréchal, as an expert on motorization, determined that the French Army would only equip two types of tanks: a fast, light tank for reconnaissance, screening, and colonial use, and a balanced medium tank.

Transall's Russian and Atlantean-designed T-37 heavy tank, briefly adopted by France as the Char-2 Lefebvre, provided an initial step towards the Commission's ideal tank, but while it was well-protected and, at the time, well-armed with a 75mm/L45 gun, it had a lower speed than desired, as well as a lower power-to-weight ratio of 13.3 hp/ton and a mediocre range. Finally, it was not particularly cheap to produce, and the hull lacked the sloped frontal armour the Commission desired. For the new medium tank, the Commission de Vincennes established a series of design guidelines and then handed over the task of producing a working vehicle to a group of designers and engineers. The Commission demanded a vehicle of thirty-five metric tons or less, with a road speed of fifty kilometers an hour, a diesel engine with a road range of at least three hundred kilometers, a 75mm/L53 gun in a three-man turret, sloped armour, and a power-to-weight ratio of at least sixteen horsepower per ton. The design group was able to achieve all of these requirements. By 1939, the Commission approved the final design and extended requests for manufacturers. Renault, AMX, Somua, ACL, Lorraine, and Batignolles-Châtillon all expressed interest in manufacturing the vehicle. As Renault was then engaged in preparing for light tank production, the initial order went to AMX and Somua, with smaller batches going to ACL and ARL.

Somua undertook early production of all vehicles from April 1941 onward, as AMX was still gearing up for high-capacity tank production. Most early vehicles produced by Somua were in fact tank destroyers (the "Druout"), which no one else produced. AMX and ARL followed several months later with tank production. ACL (Ateliers et Chantiers de la Loire) also produced Montbrun variants, focusing mainly on self-propelled artillery pieces and armoured engineering vehicles.

Further development of the initial design took place during 1941 in order to ease manufacturing issues and solve problems overlooked in the initial design. In December 1941, the first major update to the tank occurred, placing a more powerful and better-balanced 75mm/L60 gun in a new turret. In early 1944, the French Army attempted to equip the next version, the Char-8A3, with an auto-loading 90mm/L54 gun in an oscillating turret; but this version was deemed to be a failure. The Char-8A3 also initiated the use of a new diesel engine, the MD.12/40, which offered slightly more power. After a pause in production, the Char-8A4 arrived in 1945, switching to a larger 82mm/L71 gun. All Char-8A3s and a number of Char-8A2s were converted to the 8A4 standard, although AMX produced a significant number of new tanks to the same design.

CDC-8 Druout Tank Destroyer
The Druout tank destroyer, built exclusively by Somua, carried a 90mm/L40 gun in a sloped casemate. In most respects, the engine, drive-train, suspension, and tracks remained the same as the Char-8A1 on which it was based. Druouts formed the core of the four Groupes de Anti Char de Corps d'Armée, which served as the main mechanized anti-tank wing of the French Army.

DCA-8 Cyclone
The Cyclone was an otherwise standard Char-8 series tank fitted with a pair of 40mm/L60 anti-aircraft guns in a special lightly-armoured turret. This version functioned as an anti-aircraft tank.

Char-8A Series
Initial tank production focused on the Char-8A1, which carried a 75mm/L53 Mle1938 gun. This version was expected to be the standard for several years, but AMX and Somua offered a number of proposals for manufacturing improvements. Among the alternatives was a redesigned main gun, with modifications to ease loading, improve the balance of the gun, and increase the available room inside the turret for the three-man crew. A larger turret ring (175cm instead of 170cm) helped to provide more room. The modified gun, with a barrel lengthened to sixty calibers, entered service with the newly-improved Char-8A2 Montbrun in autumn of 1941. It was this 8A2 version which saw series production through 1942 and 1943. Once sufficient quantities of Char-8A2s became available, the Char-8A1 tanks were replaced, with most being converted to DCA-8 Cyclone anti-aircraft tanks. A small batch of Char-8A1s, refurbished by ARL, were given to the Philippine Army under a defense assistance scheme.


In late 1943, AMX restarted production with a new oscillating turret and the 90mm/L54 gun, as well as a newly-modified engine. This variant, the AMX Char-8A3, was intended to replace the standard tanks in the armoured regiments, providing more firepower. However, crews found the oscillating turret too cramped, and disliked the need to exit the tank to reload the three-round magazine for the autoloader. To make issues worse, the 8A3's autoloader followed a much different system than the reliable 75mm/L53 autoloader installed on the Char-6D, and it established an extremely poor reputation in the field. A hundred and ninety-five vehicles were manufactured to 8A3 specifications before the French Army cancelled further orders. The failure of the Char-8A3's turret and gun left the French Army without a viable rebuild proposal for the two thousand Char-8A1s and 8A2s that had already been produced; it had been the Army's intention to upgun the entire Montbrun fleet to a 90mm gun between 1945 and 1946.

In November 1944, DEFA offered an alternative to the 8A3's oscillating turret and unreliable 90mm loading system. An experimental high-velocity Hotchkiss 82mm/L70 antitank gun, complete with a new turret manufactured by FCM, appeared with the Char-8A4 upgrade. The new turret and the smaller gun were backwards compatible with the turrets of previous models, allowing older tanks to be refitted to the new 8A4 standard. Starting in February of 1945, SOMUA began refitting all 8A3 Montbruns with the new turret; older but more reliable 8A2 tanks were rebuilt on a larger scale (with new MD.12/40 diesel engines, drive components and new electrical systems) later in 1945. As part of the 8A4 upgrade, major improvements were made to the engine compartment, installing the engine and several other major components on sliding rails to allow for the tank's diesel engine to be removed more easily for maintenance and replacement. This halved the amount of time necessary for major engine maintenance. A small opposed-cylinder diesel engine, generating thirty horsepower, was also added. This engine did not cover the vehicle's propulsion, instead generating electrical power for turret rotation and other systems. The smaller engine could also warm and crank the main diesel engine. Armoured sideskirts, which were used irregularly on the Char-8A2, became standard in order to protect the tank's running gear from antitank rockets and light weapons. Another unusual modification added with the Char-8A4 was the addition of a simple latrine under the loader's folding seat.

Char-8A2 rebuilt as Char-8A4.

Char-8C Series
The Char-8C tank variants served as squadron command tanks (with each tank company fielding two Char-8Cs). The Char-8C was mechanically indistinguishable from the Char-8A series tanks, and the French went to some effort to keep these command tanks looking identical to the regular vehicles. However, there were some differences internally. The Char-8C1 traded a rack of MG ammunition and three main gun rounds for an enhanced transmitter-receiver set, so that the vehicle commander (and company commander) could maintain control of his squadron through communication with the regimental headquarters and the platoon leaders. Capabilities were increased in the Char-8A2, which featured a larger, more capacious turret and did not have to trade as much internal space for the radio equipment. In the Char-8C2, a jumpseat was added for a fifth crewman who could assist in operating the radio.

Alsthom MD.12/36
The engine originally used on the Montbrun was the Alsthom MD.12/36, a 36-litre V-12 diesel engine derived from the Hispano-Suiza HS-12Y aircraft engine. This engine was developed following the French Army's experience with the Russian-designed Kharkiv model V-2 diesel, which was used in the Char-2 heavy tank, and license-built in France. The MD.12/36 adapted a number of design cues from the Russian Kharkiv, but represented a completely indigenous development. From 1943 onward, the MD.12/36 was replaced by a follow-on derivative, the MD.12/40, one of the "Series Three" engines.

Alsthom MD.12/40
The MD.12/40 diesel engine was one of Alsthom's "Series Three" diesel engines, a family of diesel engines which included a V-6, a V-8, and a V-12, all using similar parts and cylinder sizes. The Series Three is designed to operate on a variety of fuels, including both regular diesel fuel, automotive petrol, kerosene, and vegetable oil (including a mix created using the Arachide or ground-nut grown in Africa). Alsthom intentionally tried to design the engine to accept a wide variety of fuels in order to avoid difficulties with fuel availability when the vehicle was used in service outside the French Metropolitan region. Use of the MD.12/40 engine started with the Char-8A3 Montbrun, although Char-8A2s were converted to use the engine during conversion to the Char-8A4 standard. All of the MD.12/40 engines used on the Char-8A4 Montbruns (but not the upgraded Char-8A3s) were fitted with a turbocharger.

Other Engines
Several Montbruns were used in various experiments with different motive power systems. One of the most novel experiments occurred in 1944 when a prototype gas-turbine unit of 560 horsepower was installed in place of the normal V-12 diesel engine, making the Montbrun the first tank to be powered by a gas turbine. While the engine was suitable for mass-production, fuel economy was significantly reduced, and the French Army gave no serious consideration to standardizing it further. The turbine-powered Montbrun remained in service at the Armoured Cavalry Branch's school in Saumer as a testing vehicle.

Another experimental variant which saw more widespread use was an Alsthom "Series 3" W-16 engine. This engine mounted a pair of Series Three MD.6/27 engines (each two-thirds the size of an otherwise-standard MD.12/40) together in a 'double-vee' setup. This turbocharged engine provided an outstanding 906 max horsepower. The engines were manufactured under contract by Bugatti and fitted to Montbruns of the Régiment de Dragons de Marine in 1945. These tanks, manufactured by Batignolles-Châtillon and officially designated the Char-8E1, were dubbed "Guépards" by their crews for their acceleration (although speed was limited to prevent damage to the drive train). Emulating the French Air Force's elite 1/2 Escadron de Chasse, the Regiment adopted a similar badge, with three running cheetahs, one representing each tank squadron in the regiment.

Char-8E1 Guépard; also roughly representative of the Char-8A4bis.

* * * * *

* * * * *

Char-8A Series - The standard tank model.
- Char-8A1 Montbrun: Standard (base) vehicle with 75mm/L53 gun.
- Char-8A2 Montbrun: Standard (base) vehicle with 75mm/L60 gun.
- Char-8A3 Montbrun: Tank equipped with 90mm/L54 gun in oscillating turret and MD.12/40 diesel engine. Weight rises to 35 metric tons. Introduced January 1944.
- Char-8A4 Montbrun: Rebuilt Char-8A2s and Char-8A3s equipped with 82mm/L71 gun; otherwise identical to Char-8A3. Introduced February 1945.
- Char-8A4bis Montbrun: New-built Char-8A4 (see above). On new production, the turret was moved slightly aft and the driver's station received three view periscopes. Introduced March 1945.

Char-8B Series - A Char-8 variant designed as an assault tank. None were ordered.
- Char-8B1 Montbrun: Uparmoured vehicle equipped with a 105mm/L28 howitzer in modified turret. One prototype built.
- Char-8B2 Montbrun: Otherwise standard Char-8B tank with flamethrower substituted for 20mm gun. Intended as an "assault tank". One prototype built.

Char-8C Series - The standard tank model equipped with extra radios. These vehicles are otherwise standard variations of the 8A series.
- Char-8C1 Montbrun: Standard command tank with 75mm/L53 gun. (Equivalent to Char-8A1.)
- Char-8C2 Montbrun: Standard command tank with 75mm/L60 gun. (Equivalent to Char-8A2.)
- Char-8C3 Montbrun: Command tank equipped with 90mm/L54 gun in oscillating turret and MD.12/40 diesel engine. Weight rises to 36 metric tons. Introduced January 1944. (Equivalent to Char-8A3.)
- Char-8C4 Montbrun: Rebuilt Char-8C2s and Char-8C3s equipped with 82mm/L71 gun; otherwise identical to Char-8C3. Introduced February 1945.

CDC-8 Druout Series - The original vehicle chassis of the series, designed as a casemate-style tank destroyer.
- CDC-8 Druout: Tank destroyer equipped with a 90mm/L40 anti-tank gun in a casemate. The Druout preceded the Char-8A into service. 270 vehicles built.
- CDA-8A, B Chasseloup: Assault gun based on the Druout hull, equipped with a 105mm howitzer (CDA-6A) or a 155mm heavy mortar (CDA-6B) in a casemate. 113 built.

CA-8 Gribeauval Series - The Gribeauval is a series of self-propelled artillery pieces built on the common hull.
- CA-8A Gribeauval: Self-propelled gun equipped with a 75mm howitzer. 45 vehicles built.
- CA-8B Gribeauval: Self-propelled gun equipped with a Canon de 105mm modele 1936 (105mm/L38). 270 vehicles built.
- CA-8C1 Gribeauval: Self-propelled gun equipped with a Canon de 155 mm GPF (L/38) 155mm howitzer. 90 vehicles built.
- CA-8C2 Gribeauval: Self-propelled gun equipped with an Obusier de 155 mm Modèle 44 howitzer. 90 vehicles converted from CA-8C1; 180 vehicles converted from CA-8B.

Marescot Series - The Marescot is a series of armoured engineering vehicles built on the common hull.
- VBG-8A Marescot: An armoured engineering vehicle with a dozer blade, digger, and 100mm demolition gun. 135 vehicles built.
- VBG-8B Marescot: An armoured engineering vehicle with a dozer blade, winch and crane for vehicle recovery. 67 vehicles built.
- PP-8 Marescot: An armoured engineering vehicle equipped with a scissors-style ten-meter bridge with a weight limit of 36 tons. Entered service in 1943. 60 vehicles built.
- VD-8A, B Marescot: An armoured engineering vehicle (similar to the VBG-8A) equipped with a mine-flail (VD-8A) or mine rollers (VD-8B).
- VBA-8A, B Boeufs: Auxiliary vehicle adopted as cargo vehicle for the CA-8D self-propelled gun (VBA-8A), and as a bridge carrier (VBA-8B).

Cyclone Series - The Cyclone is a series of anti-aircraft tanks built on the common hull.
- DCA-8A Cyclone: An anti-aircraft tank equipped with two Hotchkiss 25mm AA guns.
- DCA-8B Cyclone: An anti-aircraft tank equipped with two 40mm AA guns.


Monday, November 9th 2015, 4:00pm

AMX-40B1 Tigre, first production variant, 1946.

AMX-40 Mle.1946 "Tigre" Medium Tank

Origin and Development
The AMX-40 "Tigre" originated from the French Army's 1939 requirement for a 'heavy cruiser tank', with the objective of providing excellent firepower, maneuverability, and protection on a hull of less than thirty-five metric tonnes. The Char-8 Montbrun medium tank, a thirty-four tonne vehicle mounting a 75mm/L53 gun, entered production in 1941 to fill this role in the French Armoured Cavalry Branch. The Montbrun was the first French tank to account for developments elsewhere in Europe, such as the three-man "triplace" turret, modern suspension, and sloped armour.

While the Montbrun was an excellent vehicle for the early 1940s, and modernization efforts made it viable later in the decade, tank designers in other European nations continued to push the limits of firepower and protection. Design work for a new tank began in 1941 under the leadership of AMX chief engineer Joseph Molinié and a design committee at DEFA, replicating the earlier arrangement that had proven successful for the design of the Montbrun. The French Army approved a rise in weight to forty tons, but mandated improved firepower and protection in response.

The first mild steel prototype (designated the AMX Char Moyen 40t or AMX-40) emerged from the factory in mid-1943, being delivered to the Armoured Cavalry Branch school at Saumer for testing. AMX completed a pre-production run of ten prototypes in July 1944 which were equipped with 90mm/L54 guns in oscillating turrets. Although the autoloading system passed the initial testing stage at DEFA, field troops disliked the turret design due to its cramped crew-unfriendly turret and the need to exit the vehicle to reload the three-round magazine. Furthermore, the concern about the resurgence of chemical weapons used in Asian wars prompted the Army to require a basic level of crew protection against gas, which could not be achieved with the oscillating turret.

AMX continued development through 1944 and 1945, redesigning the vehicle to use a cast, rounded turret. Compared to the original oscillating turret, the new turret design had more working room for the crew even when 90mm and 105mm mockup guns were installed. In September of 1945, following a closed testing program at Satory, DEFA instructed AMX to begin manufacturing sixty pre-production vehicles. The Armoured Cavalry Branch officially adopted the tank as the AMX-40 Mle.1946 in October of that year. The eighteen prototype and sixty preseries tanks were designated the AMX-40A model, while production versions received the AMX-40B designation.

The Armoured Cavalry Branch originally intended to give the tank the formal name "Masséna", following the pattern laid out by the previous Lefebvre, Montbrun and Bruyere. The tank instead received the informal moniker "Tigre" following the appearance of a prototype vehicle painted in tiger stripes.

Layout and Protection
The AMX-40 followed the general layout of for a four-man medium tank, building on the practices used in the earlier Montbrun. The turret housed three of the four crew members, with the gunner located on the forward right, the commander seated behind him, and the loader in the center-left of the turret, on the opposite side of the main gun. The driver was centrally located in the front of the hull. The commander and loader had hatches in the turret roof, and the driver had a hatch located immediately forward of the turret. The commander had eight episcopes ("tank periscopes") in his hatch for visibility, while the gunner and the driver both had three (one facing forward, and two angled right and left at 45°. The loader had no sighting aids.

Both the hull and the turret were of cast and welded construction. The external surfaces were face-hardened using a Fives-Lille patented laminate welding (laminé-soudé) method which improved the performance to roughly 15-20% better than standard rolled armour, as used on the Montbrun. Most hulls were manufactured by Forges et Chantiers de la Méditerranée (FCM), although Société Métallurgique de Normandie (SMN) also produced hulls at various times. However, SMN cast most of the turrets for the tank. The glacis measured between 60 to 100mm thickness, while the hull sides varied from 40mm to 60mm. However, the glacis armour was heavily sloped and the upper hull sides were rounded, raising the effective thickness to a level sufficient to protect against some high-caliber impact. Like the rest of the visible armour, the hemispherical turret incorporated a significant degree of rounding to increase the effective thickness, and an 85mm mantlet covered the area around the gun and a portion of the turret face. A small hatch was located on the left side of the turret for loading ammunition, and the rear of the turret featured a stowage basket for miscellaneous gear.

The original DEFA design called for the AMX-40 to use a CN-90 Mle.42 F1 (90mm/L54) main gun mounted in an oscillating turret, but the turret was cancelled during 1945 due to concerns about bio-chemical warfare. The preseries and AMX-40B1 vehicles used the CN-82 Mle.45 F1 gun, which was originally designed by Hotchkiss as an experimental anti-tank gun, but was used on late-model Montbrun tanks. Although outstanding in an anti-armour role, this weapon's high-explosive shell was unreliable. Due to the gun's high firing velocity, high explosive shells occasionally malfunctioned, and on several occasions exploded in the barrel. With the 82mm gun, the tank carried a total of sixty-one rounds of ammunition, split roughly equally between high explosive and anti-tank rounds. The loadout was never standardized and generally left to the preference of the gunner or commander.

Shortly after the start of production, AMX switched over to the CN-90 Mle.42 m.46 F2 (90mm/L64). This new gun was a synthesis of the original failed CN-90 F1 design and the more successful CN-82, incorporating the automatic shell-rammer and breech block from the original design, but remained hand-loaded. This gun also incorporated a compressed-air bore scavenging system and spent cartridge case bin which prevented the buildup of fumes during shooting, a feature borrowed from the German-designed Panther tank.

The loader, seated in the left of the turret, had a ready rack of five rounds located near the gun. The remaining ammunition was stored beneath the loader's footrest in a wet-stowage rack. The gunner was seated on the right side of the turret and controlled both the main gun and the 13.2mm Hotchkiss coaxial machine gun, while the loader was tasked with operating the 6.5mm machine gun on the turret top. The gunner was primarily responsible for turret rotation by means of two electrically-actuated foot-pedals, although the commander had duplicate turret controls in order to help lay the gunner on the general fire vector.

Like the preceding Montbrun, the AMX-40 was designed to achieve a high degree of strategic mobility and reliability. The Armoured Cavalry Branch demanded that tanks be capable of making marches of up to three hundred kilometers under their own power with a low incidence of mechanical issues. Most major drive-train components were designed to last three thousand kilometers, although tracks and road-wheels were replaced more regularly. The Millot dit Laval gearbox only lasted an average of twenty-two hundred kilometers, although this was seen as marginally acceptable.

The AMX-40B1's main power came from an Alsthom "Series Three" MD.12/40 diesel engine specifically developed for use in armoured vehicles. This engine was previously used with great success in the Montbrun, and generated 680 horsepower, giving the initial AMX-40B1 a power-to-weight ratio of 17 hp / ton. In mid 1947, production vehicles shifted to use the newer Renault MD.10/46, a V-10 diesel engine that provided 782 horsepower. Like the preceding Alsthom engine, the MD.10/46 was designed to run primarily on diesel fuel, but could also be operated with regular petrol, kerosene, or even vegetable oil.

A second engine, a small Renault flat-four diesel engine able to generate forty horsepower, was installed to power major electrical components such as turret motors, lights, radios, and other electrical gear. During cold weather, the auxiliary engine could be used to warm and turn the main diesel engine, allowing the MD.10/46 to be turned off when it wasn't required. During regular operation, the small engine powered an electrically-powered compressor connected to the main engine, acting as a low-level turbocharger.

The AMX-40 used the same Auteil coil-spring suspension as the Montbrun, but used six road-wheels instead of the Montbrun's five; both the suspension components and the tracks themselves were completely interchangeable between the two tanks. The individual suspension components were externally-mounted on the side of the hull and could be easily removed for maintenance or repair.

Despite a potent engine and power-to-weight ratio, the AMX-40's speed was artificially limited to forty-five kilometers per hour in order to protect certain engine and drive train components, principally the Millot dit Laval gearbox which had been designed for the smaller and lighter Montbrun. Unlimited, the tank could reach nearly sixty kilometers per hour on paved roads, although this reduced the life of the gearbox to between a thousand and fifteen hundred kilometers. The speed governor could be deactivated in the field with a specialized tool, or alternately a hammer (although this practice was officially discouraged). While the governor limited the AMX-40's top speed in comparison with the preceding Montbrun, the AMX-40 had better off-road speed on rough ground, equivalent climbing and crossing capacity, and slightly lower ground pressure, which improved its mobility in muddy or sandy conditions.

Other Features
Among the advancements included on the AMX-40 was the Sentinelle Mle.45 main gun stabilization system. This device, manufactured by La Sentinelle de St-Quentin - Tir et Préparation Militaire, used a series of gyros to measure the movements of the tank, and automatically made minor adjustments to the gunlaying drive to keep the gun more stable during vehicle movement. The Sentinelle Mle.45 stabilizer represented a marked improvement upon the preceding Mle.42 used on the Montbrun, which measured movement in only the vertical axis, and used electric rather than hydraulic gunlaying drives. The improvements allowed the AMX-40 to achieve a reliable 75% hit ratio against targets at a range of one kilometer while moving. The Nice-455 stadiametric rangefinder was also installed, with the two optics located on the upper side of the turret.

All vehicles were equipped as standard with the ER 56 Mle.44 tactical radio, which allowed for transmission by morse key and voice over the range of approximately eight to ten kilometers. The ER 56 radio was located behind the commander, who was primarily trained in its operation. The loader was trained as the backup radioman. AMX-40B1C command tanks, used by company and battalion commanders, carried an additional ER 58 Mle.43 radio with greater range (up to thirty kilometers) for purposes of collaboration with higher formations. All four crewmen were provided with headsets for communication, and an additional telephone-style handset located on the rear of the tank. This telephone allowed for infantry to communicate with the tank's crew when the vehicle was buttoned up.

Several additional features were introduced to raise the level of crew comfort in the AMX-40. The loader's seat folded up to reveal a portable latrine that could be emptied out the bottom hatch in the hull, a feature that was first adopted on the Char-8A4bis; this made it possible for the crew to operate more comfortably in a bio-chemical warfare environment. The loader also had access to a small electrically-powered cooker in the space behind his seat that could be used to heat coffee or pre-cooked meals.

Specifications (AMX-40B2)
Crew: 4 (commander, gunner, loader, driver)
-- Length: 7.1m (hull); 9.55m (includes gun)
-- Width: 3.25m
-- Height: 2.8m overall
Weight: 40 metric tons (base weight); most models around 42 metric tons
-- CN-90 Mle.42 m.46 F2 (90mm/L64) main gun
-- 13.2mm Hotchkiss MG in turret (coaxial)
-- 2x6.5mm cupola MG
-- 2x3 81mm smoke grenade launchers
-- Main Engine: Renault MD.10/46 V-10 diesel, 782hp
-- Auxiliary Engine: Renault R 4-cylinder diesel, 40hp
Transmission: Manual
Suspension: Auteil coil spring; six road wheels with two return rollers
Track: 500cm by 52cm caterpillar track
-- Turret: 105mm (face), 60mm (sides), 40mm (rear), 20mm (top)
-- Mantlet: 85mm
-- Glacis: 60 to 100mm (cast, sloped and rounded at average 60°)
-- Hull: 60mm (forward sides), 40mm (aft sides), 20mm (hull top), 30mm (hull bottom)
Power Weight Ratio: 18.6 hp / tonne
Equipment: Nice-455 stadiametric rangefinder, Sentinelle Mle.45 main gun stabilizer, ER 56 Mle.44 tactical radio
Constructors: AMX, FCM
Speed: 45kph (limited road), 30kph (offroad)
Range: 330km; 560km with external tanks
Prototype Vehicles - A Series
--- AMX-40A1: Prototype with 90mm gun and oscillating turret. Ten built.
--- AMX-40A2: Prototype with improvements to drive-train and commander's cupola; four vehicles were rebuilt from AMX-40A1s.
--- AMX-40A3: Prototype with 82mm gun and Montbrun turret. Two converted from AMX-40A1s.
--- AMX-40A4: Prototype with 82mm gun and hemispherical turret, as well as improvements to the sights and electrical systems. Four vehicles constructed.
--- AMX-40A5: Preseries vehicle, equipped with CN-82 Mle.45 F1 gun and multi-axis stabilizer; based off the AMX-40A4 prototype. Thirty-nine built, later converted to AMX-40B1 standard.

Production Vehicles - B Series
--- AMX-40B1: Production vehicle with CN-82 F1 Mle.45 gun.
--- AMX-40B2: Production vehicle with CN-90 Mle.42 m.46 F2 gun.
--- AMX-40B3:Production vehicle produced from 1948 onward

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- Excellent 82mm or 90mm main armament with good penetration and accuracy, even on the move
- Good cross-country mobility and general reliability

- Gearbox has short lifespan
- Mediocre top road speed of 45 km/hr (artificially limited)