Categories
WW2 French Projects

Renault VM Early Design Version

ww2 French Tanks France (1931)
Light Armored Reconnaissance Vehicle – Design Only

During the interwar years, the French Army’s cavalry service was a force actively seeking new types of vehicle to introduce to its forces, generally more so than the better-funded infantry. There were active doctrinal developments within the Cavalry which led to new roles being created, for which various manufacturers would offer designs. In the early 1930s, the concept of a very light vehicle tasked with reconnaissance duties and armed with a machine gun was gaining popularity within the Cavalry. The Citroën P28 was the first vehicle adopted, in 1931. Renault, the largest vehicle manufacturer in France, did not want to allow its competitor Citroën to gain the lead and be able to sell vehicles to the French Army uncontested. As Citroën had done, it began the design process based on a logistical armored vehicle it had recently designed. A turreted light tank/tankette model designed in this manner was already in existence by late 1931.

Reconnaissance Vehicles and Citroën’s Successes

The French Cavalry ended the First World War with a varied fleet of armored cars of various weights, sizes and armaments. In the interwar years, the need for new, more modern vehicles was apparent, including vehicles which could fulfil a reconnaissance role.

In July 1930, the French Army approved an ambitious program which was to lead to the creation of vehicles to fulfill a large variety of roles. This was the general motorisation program. It called for two types of vehicles which would fulfil a reconnaissance role: a voiture de reconnaissance tout terrain blindée (Eng: all-terrain reconnaissance armored car) and a Automitrailleuse légère tout terrain (Eng: all-terrain light armored car). “Automitrailleuse” is a term that, although often translated as armored car, when used in the context of interwar French Cavalry, is used to designate all armored combat vehicles, regardless of means of motion. In other words, a program that, in English, would be translated as an armored car program, could in fact refer to a half-track or fully tracked

The first requirement would eventually evolve into the Type L armored car specification, for which Renault would produce the ill-fated Renault URL armored car.

The armed Renault UE prototype. This was an experimental prototype created shortly after the early VM for demonstration purposes, with the only change from the original UE being a raised compartment for the co-driver, who was tasked with operating the machine gun. Source: Renault documentation via Les Automitrailleuses de Reconnaissance, Tome 1: L’AMR 33 Renault, François Vauvillier

In comparison, the second set of requirements would quickly fall under the influence of a specification for a vehicle which would be ordered in much higher numbers – the Type N. The Type N was envisioned as a lightweight all-terrain, lightly armored infantry tractor and cargo vehicle. Three companies produced vehicles for this program: Latil offered a licence-built Carden Loyd Mk.VI; Citroën offered the Citroën P28 chenillette, a half-tracked vehicle; and Renault offered a tankette, inspired by the general design features of the influential Carden Loyd but by all means its own design. This was the Renault UE, a light (2.64 tonnes) and tiny (2.8 m long, 1.74 m wide, and 1.25 m high) tankette with a crew of two and protected by thin, bulletproof armor. It had a leaf spring suspension with three bogies containing two road wheels each, using a front sprocket and rear idler and supported by two return rollers.

Creating a Reconnaissance Vehicle Using the Renault UE as the Basis

The specifications of the Type N, which called for a lightweight, fairly mobile, bulletproof vehicle, co-incidentally proved to create designs which would provide a good basis for the kind of light reconnaissance vehicles the French Cavalry was seeking. Both Citroën and Renault would offer vehicles to fulfill such a role based on their logistical tankettes. Citroën offered a modified version of its P28, which was ordered in October 1931.

The Renault design was created around the same timeframe as the Citroën, in autumn 1931. The design would retain the same very short length of 2.8 m as the UE, and perhaps the same or at least a similar width of 1.74 m. However, there were major structural changes to the vehicle. Renault gave this modified design the internal code “Renault VM”.

Instead of retaining the front crew compartment, centrally-placed engine, and rear-mounted stowage area of the original UE, the VM’s crew compartment would instead be placed towards the left and rear of the vehicle, with an engine to the front and right.

A side schematic view of the early Renault VM, showing the similar drivetrain in comparison to the UE, as well as the turret and crew positions. Source: Renault documentation via Les Automitrailleuses de Reconnaissance, Tome 1: L’AMR 33 Renault, François Vauvillier

The largest difference in the vehicle design was the presence of a turreted armament. The early VM design featured a turret which was mounted on the left of the vehicle, behind the driver’s position, which was positioned in the same way as on an UE. The turret featured on the schematics of the vehicle was a fairly simplistic design. It would be armed with the new machine gun available for fortifications and armored vehicle designs, the 7.5 mm MAC 31. The MAC 31 Type E had a weight of 11.18 kg empty and 18.48 kg with a fully loaded 150-round drum magazine. The machine gun was gas-fed, and had a maximum cyclic rate of fire of 750 rounds per minute. It had a muzzle velocity of 775 m/s. The ammunition stowage present on the early Renault VM design is unknown. The turret would have housed a single crewmember, the gunner/commander. It appears that a small cupola would have been placed towards the rear of the turret, and would likely have had some sort of vision device, such as a panoramic periscope. From the design, the turret appears to have been very small overall, to the point it would have been quite cramped. It also appears that no reloads for the machine gun would be present in the turret, with all the magazines (the MAC 31 using 150-rounds drum magazines) having to be stowed inside the hull instead.

The other major structural change of the early VM design in comparison to the UE was the engine, with the early VM being designed to have a more powerful engine. Its potential horsepower output is unknown, as Renault used an alternative means of power measurement for it, CV. It would have been a 15 CV engine. In comparison, the original UE’s Renault 75 was a 10 CV engine producing 30 hp, while the AMR 33’s 24 CV engine would produce 84 hp. Unlike the centrally-mounted position on the UE, the engine was shifted to the right on the early VM design. This would have been a fairly uncommon feature at the time. As lateral space was quite limited, the radiator and ventilator would have had to be shifted at 90° and be installed to the rear of the engine, in a fairly distinct manner which would have also been quite rare at the time. The radiator, in particular, would have been installed as far to the back as the turret would have been, and the gunner would have effectively been sandwiched between the radiator on his right and the hull’s wall to the left.

A top view of the early VM design’s structural arrangement, showing the position of the crew as well as the engine block, which extended over the whole short 2.7 m length of the vehicle. Source: Renault documentation via Les Automitrailleuses de Reconnaissance, Tome 1: L’AMR 33 Renault, François Vauvillier

The suspension of the vehicle would have used the same components as the Renault UE, with three leaf springs bogies on which two small road wheels were mounted, a front sprocket and a rear idler. However, unlike on the UE, the sprocket and idler would have been placed higher. Though the return rollers are not seen on the schematics, they would very likely have been present.

Armor protection at this point in time would also very likely have been the same as the UE, with 9 mm on vertical surfaces and 6 mm on all other plates.

Rejection

Renault’s early VM design was submitted to the technical services of the French Cavalry at some point in autumn 1931. The vehicle was formally rejected by the French Cavalry on November 12th 1931.

A first review of the design by the French Cavalry was fairly negative. Several design choices of the vehicle were deemed subpar and proved unpopular, as some of the design features were quite unconventional for the time. Among which was the rear-turreted configuration, which the French Army would continue to object to on future evolutions of Renault’s light armored vehicle proposals. Another source of discontent was the engine’s offset mounting to the right. Furthemore, the engine was not thought to be powerful enough to allow for the vehicle to reach a high enough speed. This was further worsened by the use of a suspension almost identical to the UE, with six small road wheels mounted on leaf springs, which would generally favor cross-country mobility but make reaching higher maximum speeds harder. There were also issues with the proposed placement of the radiator all the way to the right, with the position of the commander, cramped between the radiator and the left wall of the vehicle.

During the same period, the French Cavalry had been somewhat pleased with the design of Citroën’s offer, the P28, and had ordered 50 vehicles of a modified version of the half-track tractor, now fulfilling a light reconnaissance vehicle role. As such, there was no immediate need for a swift replacement at this point in time, though the P28 was not viewed as a viable long-term solution but only as a stopgap.

Conclusion – A Failure which would Lead to Many Successes

The rejection of the early Renault VM in November 1931 would not be the end of Renault’s light reconnaissance vehicle designs, far from it. The P28 was considered to only be viable as a stopgap solution, and there was still a need for a more capable vehicle to offer a more durable reconnaissance platform. Formal specifications for such a vehicle would be formulated by the French Army on January 16th 1932.

One of the five Renault VM prototypes, n°79 756, is seen during the large French Army maneuvers of summer 1932. Source: Les Automitrailleuses de Reconnaissance, Tome 1: L’AMR 33 Renault, François Vauvillier

Renault would provide a modified version of its existing VM design, which would undergo many changes, most notably, a lengthened hull allowing for less tight and cramped spacing, a more powerful engine, and a new suspension and turret designs. Five prototypes of this design would be ordered in April 1932 and, in a true industrial feat at the time, completed in time to participate in large French Army maneuvers in the summer of 1932. These would eventually lead to the AMR 33, of which 118 new production vehicles would be manufactured in addition to the five prototypes. After this the even more produced AMR 35, a further evolution of the VM design, came. These were two success stories for Renault’s 1930s armored fighting vehicles design, despite the failure of the original VM design.

Renault VM concept as illustrated by Pavel Alexe, funded by our Patreon campaign.

Renault VM Early Design Version Specifications

Dimensions (L x w) 2.7 x likely 1.78 m
Suspension Leaf springs
Road Wheels 6
Engine Renault 15CV engine
Crew 2 (driver, commander/gunner)
Armament 7.5 mm MAC31 machine gun
Armor 6-9 mm

Sources

Les automitrailleuses de Reconnaissance, Tome 1: l’AMR 33 Renault, François Vauvillier, Histoire & Collection editions
Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions
Char-français: http://www.chars-francais.net/2015/index.php/engins-blindes/automitrailleuses?task=view&id=70

Categories
Has Own Video WW2 French Projects

Jacquet Assault Train

ww2 French Tanks France (1944)
Articulated Vehicle – Design Only

Victor-Barthelemy Jacquet is not a French designer with golden name recognition, like Louis Renault or Colonel Jean Estienne, the fathers of the Renault FT and French tanks respectively. Indeed, virtually nothing is known of him outside of a few patent applications submitted between 1922 and 1944. It is this final patent, submitted at a time when France was being liberated from the Germans by the Allies, which was perhaps one of the oddest tank designs of the war – a train tank or, in modern parlance, a cybernetically connected articulated armored fighting vehicle.

The Man

Little can be found about Victor-Barthelmy Jacquet. What is known is that he submitted his first patent in France in 1922, followed by 7 more filings in Great Britain and France over the next 22 years. His penultimate patent was for this ‘train d’assaut’. His patent filings were technical in nature and showed a degree of engineering mechanical competency, so it is fair to assume that Jacquet at least had a degree of engineering knowledge. When it comes to the ‘train d’assaut’, there are not many clues from which to work for providing additional background on Jacquet, not even his address at the time. However, this was disclosed in the 1922 application in Great Britain for a patent on his reversible motor pump. At that time, he was living at 20 Boulevard de Villiers, Levallois-Perret, right in the heart of Paris. Today, this is a rather anonymous and mundane white apartment block with commercial premises underneath. Where Jacquet may have resided 22 years later is unknown, nor is the reason for the hiatus from 1922 to his next patent in 1943.

A French ancestry site (geneanet.co.fr), which cannot be verified, shows a trace of a Victor-Barthelmy Jacquet born in Montbrison, west of the city of Lyon on 6th December 1883 and dying in Paris on 7th May 1947, aged 67. If that entry is correct, then Jacquet was born as one of 11 children and had served in WW1 (1914-1919). He would have been 31 years old at the outbreak of WW1, and 39 when he submitted that first patent. At the outbreak of WW2, in 1939, he would have been too old for military service at 56 years of age and in 1944, when he submitted this assault train idea, 61.

He is certainly not to be confused with Victor Eugene Alexandre Jacquet from Montbrisson, born two years later (1885) and who died in 1946. That Jacquet was a poet and may have been a relative or just someone sharing a similar name, it is unclear which. If geneanet.co.fr has the correct Victor-Barthelmey Jacquet, then this Victor Eugene Jacquet is not a sibling.

Design

The design of Jacquet’s assault train was simple and complex, all in one package. Simple in theory and complicated in design. The fact that this was as far as it went belied the fact that to put such a vehicle into use would border on the fiendishly complex. Consisting of 3 distinct and different sections, known as ‘cabins’, the design connected all three of them together with a hydraulic coupling allowing for independent movement. In total, this vehicle would amount to some 6 to 7 meters long, with around 0.5 m of ground clearance. Using hydraulic pressure, the coupling could also be locked to assist in obstacle crossing. Each section had its own independent track system and turret.

Jacquet’s assault train, as seen in his 1944 patent application, climbing a short escarpment. The image has been digitally cleaned for clarity.
Source: French patent FR99201

The unusual shape of all three cabins left the leading section angled down and forwards, rather akin to the shape of the bonnet on a car. All three cabins were vertically sided with a rounded upper hull. The turret on cabin 1, mounted in the center of this part of the vehicle, could, therefore cover a very shallow angle to the front – ideal for spraying fire into the steep angle of a trench or for when this leading cabin cleared a slope. It also allowed for the turret on the larger and longer cabin in the middle to overlook the entirety of cabin 1, including its turret, meaning it could also fire to the front as well as to the sides. The third cabin, in the rear, was, like cabin 1, small and angled with a turret operating canted. The angle of the hull roof slope was not as sharp as that on cabin 1. Cabin 3 was also slightly larger than cabin 1 as well. All three turrets followed the same shape.

Harder to tell from the side image was that the leading cabin was also narrower than the main cabin in the middle. This allowed for weapons mounted in the leading edges of this central cabin to fire past the forward cabin.

Front view of Jacquet’s Assault Train. No armament shown in the foremost turret. Modified and adapted from French patent FR99201.

Suspension

All three cabins were tracked, using a relatively straightforward system consisting of a large drive sprocket and a toothed idler at opposite ends of the track. Between these large wheels were what appears to be four double sets of wheels connected together in pairs on either side of a heavy inverted elliptical spring, allowing vertical movement of the bogies. Each bogie was effectively split in two, with one wheel-pair in each piece and the two pieces connected together via a pin, allowing the wheel pairs to move slightly independently of each other. The inner of those two-wheel pairs, consisting of the inner half of each bogie, was connected by another set of leaf springs. To add to the suspension provided by those two sets of elliptical springs, a third set, consisting of half-elliptical springs, was fixed firmly at the top to the hull side and flexibly at the bottom to the foremost wheel on the foremost bogie. The rearmost end of the rearmost bogie was affixed to the hull via a vertical arm and, thus, the entire system could move as one, individually or as bogies. Whilst that is simple enough, albeit far from modern for a tank in 1944 which could be on a more modern system, like volute springs or torsion bars, it was still viable.

The suspension system for each of the cabins of the Assault Train. Note that the tracks are facing left to right. Modified and adapted from French patent FR99201.

Automotive

The center cabin carried the engine and primary gearbox for the vehicle, ensuring that the heaviest mechanical components were mounted close to the center of gravity. From there was a rather complicated system of secondary drive elements to carry power from this primary gearbox to the drive sprockets at the back of the center cabin and, via a long drive shaft, to a powered differential at the rear of the rearmost cabin. Although not shown in the plan view drawing in the patient, the output from the gearbox also went forwards down the center line of the vehicle to the front cabin, to presumably another powered differential at the front of the tracks.

Plan view of the main cabin (right) and the smaller fore or aft cabin (left). The image has been digitally cleaned for clarity. Source: French patent FR99201
Seating position for the crew in the center cabin of the vehicle is shown along with the steering levers. The image has been digitally cleaned for clarity. Source: French patent FR99201

Steering for the vehicle was delivered by means of levers and pedals for braking the tracks, accelerating the engine, and also controlling the hydraulics for moving the cabins in what must have been the most complicated driving job imaginable. This would be made worse by the fact that the driver was positioned high up centrally in the middle section of the vehicle, using the turret for visibility. This meant his view forwards on the ground would be totally obscured by the leading cabin.

Armament and Protection

Protection for all three cabins of the vehicle was provided by a body that was well rounded and made from cast type of steel of either manganese steel or another suitable alloy. Inside this cast steel shell would be the necessary supports, pre-made for the attachment of all of the mechanical components, such as the engine and transmission.

Weapons for the assault train are unnamed but, in his patent application, Jacquet describes how the cast steel body would come with supports cast to hold various components and weapons and any “.. liquids, gases, compressed air, etc., necessary for …. The defense of the assault train”. Whilst some of those elements may also form parts of the propulsion or fuel system, there is clearly also the potential envisaged for at least the use of hazardous liquids and gases for defensive purposes, effectively meaning either something corrosive, poisonous, and/or flammable.

To add to the burden and the otherwise difficult working position of the driver, he would also find himself sat alongside the primary armament of the cabin, which was fitted in the turret.

The rear cabin was designed to house a single 75 mm gun which, very oddly, was pointed directly backward out of the hull of the cabin rather than in the turret. Aiming the gun would therefore be a function of aiming the entire rear of the vehicle at the target. The patent further elaborated on armament by suggesting that other anti-tank guns, machine guns, or a “compressed air mine tube against anti-tank barriers” could be added, without providing any conception as to what that weapon might look like.

As a basic outline of the armament spread across the three cabins and turrets, there would be 4 machine guns and 2 cannons and the drawing clearly shows at least two of those machine guns protruding from the forward face of the central cabin. It is logical to assume that some armament would be mounted in each turret. Given that the leading cabin had the turret so sharply canted, there seems little point in a large cannon in that turret, being so limited in use. A reasonable estimate, therefore, of armament might be for just a single machine gun in that leading cabin’s turret, two in the sides of cabin 2, and a single machine gun in the turret of cabin 3, making 4 in total. With a large caliber gun presumably for firing high explosive shells, like the French 75 mm, in the rear of cabin 3, this would only leave the turret in cabin 2 to find a suitable armament for. Given the small size of the turret and the fact that the driver is also sharing it, whatever cannon or other armament mounted therein would have to be fairly small and would serve to complicate both driving and firing.

Crew

No specific crew is listed or detailed by Jacquet but, based on his drawings and description, an estimate can be made. Only one man was needed to drive the vehicle (cabin 2) along presumably with a commander – again, best positioned in the turret of cabin 2, and therefore probably having to operate the gun as well. At least one other crewman would be needed in cabin 2 to operate the hull machine guns on one side and two men if both were to be operated at the same time, for a total of 3-4 men (commander, driver, machine gunner x 2) in cabin 2.

Cabin 1, with no driving to do, would need at least one man to operate the gun and possibly a second to assist with loading or observation (machine gunner, assistant). The same is true in the rearmost cabin (cabin 3), with the added complexity of the large field gun which would need at least two men to operate so that it could be loaded, aimed, and fired with any degree of alacrity. That would mean not less than 3 and more likely 4 men (turret machine gunner, field gunner, two loaders) there. This means that across the three cabins, at least 8 and maybe as many as 10 men would be needed to operate the entire vehicle.

Articulation

This was certainly not the first articulated fighting vehicle concert. The first of the modern era was from British Colonel R. E. B. Crompton in 1915, with two tractors connected back to back in an effort to make a longer tracked vehicle for crossing trenches. It is this obstacle crossing ability which was, and still is, appealing to designers of articulated vehicles, like the plan for a set of additional tracks on the front of the St. Chamond in WW1, Delahaye’s 1918 design for a multi-tracked articulating vehicle, or the design for connecting a whole series of tanks together from M. Boireaux in 1936. They all used this characteristic to dramatically move one set of tracks from the other to increase the mobility of the vehicle over rough terrain or obstacles.

It is not known if Jacquet knew of some or any of these preceding ideas or not or if this was just a case of convergent thinking. Either way, the outcome was the same – using a system of articulation of one or more sections of track, whether independent on a chassis or not, to increase obstacle crossing.

The means by which Jacquet’s vehicle was to cross an obstacle was, much like the other ideas, to use one or more sets of tracks on a body or bodies. For Jacquet, in his three-cabin vehicle, it was the smaller leading cabin that led the way in crossing obstacles and this was achieved with a hydraulically controlled bearing between the cabins, which allowed for both vertical and horizontal movement. Cabin 2, the larger of the three cabins and located in the middle, provided the bulk of the system, with the third cabin at the back acting almost as a tail and balance for the whole lot. Between the cabins were effectively spheres, with a third of the front and rear removed and with the remaining part able to fit into the adjoining piece, giving the appearance of a concertina effect when in operation. For the connection between cabins 1 and 2, this was formed from three such ‘cut spheres’ forming the connection, but only two for the connection between cabins 2 and 3.

The three cabins of Jacquet’s Assault Train seen from above, showing the horizontal movement available to it. Note that the image has been digitally cleaned for clarity.
Source: French patent FR99201

When the system came to a vertical obstacle, such as a wall or even a cliff up to the height of the whole vehicle, it would begin to scale it by elevating the leading cabin hydraulically. Lifting this off the ground and then moving cabins 2 and 3 forwards would push cabin 1 up the cliff. As cabin 1 got to the top, the middle cabin would come off the ground but be hauled forwards by the trailing cabin, helping to provide forward thrust, as well as what traction cabin 1 could purchase at the top of the escarpment. As cabin 1 cleared the top, this tractive effort increased and brought cabin 2 to the top just as cabin 3 started to leave the ground and provided less and less traction.

Diagrammatic cross-section of the leading section of the vehicle, showing the engine and primary gearbox, along with the circles indicating the articulation. The rounded body work is also apparent. Note that the image has been digitally cleaned for clarity.
Source: French patent FR99201

Thus, all the pieces of the vehicle would act in sympathy with each other. As one piece lost traction, the others gained it, balancing out the forces needed. Even in the case of a vertical face, the system could work on paper.

The means by which the tank could climb a sheer cliff face as tall as itself.
Images adapted and modified from French Patent FR907544.

In the case of a wide gap, such as a particularly unpleasant anti-tank ditch, river, or canal, the system still worked. However, instead of elevating the leading cabin of the vehicle, the coupling could be locked and cabin 1 pushed ahead into the gap. As long as the center of gravity of the vehicle was not exceeded in pushing this leading cabin out in the void, the whole train would remain level on the other side of the gap. By the time cabin 1 reached the other side, cabin 2 would be exiting the bank, and cabin 1 would be pulling it across and so on for cabin 2 and cabin 3, with the coupling locked. Assuming that the gap allowed for a small dip onto the facing bank, like crossing a river, then the gap crossable could be even larger than that of the distance to the center of gravity. This relatively small vehicle of three parts possessed a remarkable level of agility which would set it apart from a more conventional design.

Original page from Jacquet’s patent.

Conclusion

Jacquet’s Assault Train swerved headlong into oblivion as a design. Once the basic elements were drawn as they were, Jacquet had committed the vehicle to an impossibly complex drive and hydraulic system to navigate even relatively modest obstacles. Hard to drive, complex to maintain, impossible to command to any effect, the vehicle rightly was as poorly thought-out as it was likely for production or adoption.

Many of the same problems with articulated vehicles which existed prior to this design and which continued to exist thereafter, such as control over the separate sections of the vehicle, how to command and operate it, how to effectively lock and release a hydraulically actuated flexible coupling, were unresolved. Jacquet’s solutions were just like his suspension design – simple in thought, complex in practicality and worse than every other available alternative. There was absolutely no likelihood of this design reaching any stage of trials or production with an armed force as it was laid out. If the technical issues were not bad enough, then the ludicrous number of crew required to operate it should be sufficient to kill it off. A vehicle needing 8 to 10 or more crew was simply never going to be a viable concept when contemporary vehicles fielded by Britain, France, the USA, and the Soviet Union, were 4 and 5 man crews for substantially more tank for the effort.

A slight ray of light for the vehicle was the basic concept of articulation. Whilst it was certainly not new at the time, it was at least clear on how an articulated vehicle of more than 2 sections could have an advantage over a 2 piece design. Namely, a three-piece vehicle could climb even higher obstacles or cross even greater gaps using that third cabin at the back as a tail. Nonetheless, the patent was accepted in July 1951 and quickly filed and forgotten.

5-way vies of the Jacquet Assault Train, showing off the articulated design and the odd turrets.
Front-right view of the Jacquet Assault Train cresting a rise. The advantages of the articulated design are evident.
The same from the rear. All renders done by Giganaut, funded by our Patreon campaign.

Specifications – Jacquet’s Assault Train

Crew: est. 8 – 10 men (driver, commander, machine gunners x 4, artillery gunner, loaders x 2)
Dimensions: 6 – 7 metres long. 0.5 m ground clearance.
Armor: cast steel or manganese or other alloy cast armour
Armament: Optional single 75 mm cannon, anti-tank guns, multiple machine guns, compressed air explosive launcher

References

French Patent FR545918 Moteur rotatif reversible, filed 14th January 1922, granted 4th August 1922, published 4th October 1922
British Patent GB191718 Reversible Rotary Motor or Pump, filed 29th December 1922 – application not accepted.
French Patent FR887564 Dispositif Differential, filed 6th November 1942, granted 16th August 1943, published 17th November 1943
French Patent FR897490 Disposif de changement de vitesse, filed 24th August 1943, granted 30th May 1944, published 22nd March 1945
French Patent FR90371 Machine rotative, filed 6th June 1944, granted 10th September 1945, published 8th April 1946
French Patent FR906066 Motor-thermique, filed 25th July 1944, granted 7th May 1945, published 21st December 1945
French Patent FR99201 Train d’assaut, filed 25th September 1944, granted 18th July 1951, published 24th October 1951
French Patent FR907544 Disposif de transport a patins et roues commandees, field 31st October 1944, granted 2nd July 1945, published 14th March 1946
Forehistoire.free.fr http://forezhistoire.free.fr/56-ph-victor-jacquet.html

Categories
WW2 French Projects

Renault DAC1

ww2 French Tanks France (1939-1940)
Fast Tank – Project Only

In the 1930s, France had a vast tank industry with a large number of different manufacturers competing to provide armored fighting vehicles for the Army. The cavalry combat tank France adopted in 1935 and produced from that point onward was the Somua S35, a 19.5 tonnes, decently armored and mobile tank armed with the 47 mm SA 35. In the late 1930s, the project that was most probable in succeeding the Somua was an incremental evolution, the Somua S40. This did not mean, however, that other manufacturers were not seeking to produce designs to fulfill a similar role and potentially replace the Somua. Whilst AMX presented a fairly well-known design in 1940, the AMX 40, which would fulfill a similar role to the Somua, a much more obscure design was also created by Renault – the DAC1.

Le Somua de Billancourt

The DAC1 design by Renault appears to date from 1939 or 1940. The company had previously, in 1936, been stripped of its armored vehicles manufacturing service located in its factory of Issy-Les-Moulineaux, which was nationalized and became AMX (Atelier de Construction d’Issy-Les-Moulineaux – Issy-Les-Moulineaux Construction Workshop). Renault would, however, quickly resume its own tank-building efforts in its own facilities of Billancourt. Prior to the AMX split, Renault had designed some vehicles for the cavalry, including the AMR 33 and AMR 35 light reconnaissance tanks, but also the AMC 34 and AMC 35 tanks which fulfilled the same AMC role (Automitrailleuse de Combat – Combat Armored Car, with the term armored car designating any combat vehicle of the French cavalry in the interwar era, regardless of it using wheels, tracks, or half-tracks). Those designs, while having the advantage of a two-man turret, otherwise used riveted and bolted construction with thin armor, and the later iteration, the AMC 35, was notoriously unreliable. Renault did not produce any cavalry tank that could compete with the well-armored S35 produced by Somua.

This very simplistic sketch is the only known visual of the DAC1. The text at the top right says “at project stage”, while the one at the bottom is 16 tonnes tank (Renault DAC1). Source: Tous les blindés de l’armée française 1914-1940

The DAC1 appears to have been an attempt by Renault at creating such a vehicle, and the project received the name “Le Somua de Billancourt” (“The Billancourt Somua”). The project is incredibly obscure and is known from a single outline as well as very few specifications.

The DAC1 was to be a 16 tonnes fast tank with a crew of three. It has also sometimes been noted that it was a competitor to the AMX 38, a vehicle which was, by all means, an infantry tank, causing some confusion.

The vehicle’s profile indicates a gun that was most likely the 47 mm SA 35, the same armament as used in the second production run of the Renault D2, the Somua S35, and the B1 Bis. A coaxial machine gun, almost certainly a 7.5 mm MAC31E, would be present to the left of the gun. The design of the turret features a prominent cupola, more so than most French designs of the era.

The hull has a very basic shape, with a seemingly sloped frontal plate, and only a moderately-sized section appearing over the suspension, suggesting a fairly high suspension run. The only distinct elements of the hull appear to be what would suggest a rear transmission.

The suspension type the vehicle would have used is unknown, and it is uncertain if this was ever determined by Renault engineers. This would likely have been a suspension type at least to an extent optimized towards maximum speed, which would differentiate the DAC1 from several late 1930s vehicles, such as the R40, which opted for the “AMX-type” suspension with a large number of road wheels, optimized for cross-country mobility over road speed.

Planned American Exile

Prior to June 1940, France had some fairly deep military-industrial ties with the United States, with France being the largest foreign customer of the American military-industrial complex prior to the Fall of France. Armored fighting vehicles were not the main point of interest for the French in America, with American armored fighting vehicles of the time not really fitting in any role the French Army desired.

However, another way of using America’s vast automotive industry to provide France with armored fighting vehicles had been considered. This would have been employing American factories to manufacture vehicles designed by French manufacturers. While this would require some efforts, notably tooling-wise, it could potentially allow France to exploit a much larger industry than its own.

Already considered before the campaign of France, this option became increasingly popular during the month of May and early June 1940, when the situation of French troops and France’s ability to retain its territories looked increasingly bleak, but the negotiation of an armistice with Germany was not yet certain. The French would notably send a mission, reportedly headed by AMX engineer Joseph Molinié, to the US to evaluate such a possibility.

It appears the DAC1 was one of the various designs considered for production in the United States, though reportedly, the American-made DAC1 would have its crew reduced to just two. It is unclear why the DAC1 in particular was considered for production in the US. However, by picking a design that was yet not complete, perhaps it was hoped that the last design phases would be undertaken in US standards and would perhaps allow for an easier start of production, in comparison to adapting tools and plans of an already in production or fully designed vehicle, such as the B1 Ter or S40 to US measurements and production standards.

Conclusion – One of the Most Obscure French Tanks

Any plans to produce the DAC1, or another French tank for the matter, in the United States was abandoned after the armistice with Germany entered into effect on 25th June 1940. Later in the war, a secret service within the Vichy Army, bent on resisting the Germans, the CDM, would hope to produce some of its design, such as for example the SARL 42, in foreign countries, the US being the obvious contender. This would never materialize either.

The DAC1 is easily one of the most obscure French tank designs of the late 1930s, with very little known of the elements and capabilities the vehicle would have had. Nonetheless, its crew of two or three suggest it would have likely retained the one-man turret which plagued French tank designs of the 1930s, handicapping an otherwise sound design. At just 16 tonnes and with a 47 mm SA 35 armament, it is also likely such a tank would have been far from groundbreaking by the time it would reach prototype stage or enter production, and would not provide a good evolutionary potential for later stages of the war.

A highly hypothetical view of the Renault DAC1 fast tank. Illustration created by Pavel “Carpaticus” Alexe.

DAC1 specifications

Weight 16,000 kg
Transmission Likely rear
Crew 2 to 3
Armament Likely a 47 mm SA 35 main gun and coaxial 7.5 mm MAC31E machine gun
Numbers produced 0

Sources

Les véhicules blindés Français 1900-1944, Pierre Touzin, EPA editions, 1979
Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions

Categories
WW2 French Projects

Renault Improved Battle Tank

ww2 French Tanks France (1939)
Battle Tank – None Built

In 1939, France was on the cusp of a new war with Germany. At the time, many foresaw a return to the static type of attritional warfare of World War One. France was very well set for this type of warfare, with large numbers of well-protected tanks and the formidable Maginot Line on which was hoped to crush any German attack.

The great tank designer and industrialist Louis Renault had been a hero in the First World War with his groundbreaking 2-man FT design. Through the interwar years, his was a magical name in manufacturing and vehicle design, as famous for his cars as for his tanks. It is perhaps odd therefore that, in 1939, with a new war declared against Germany, he submitted a design not so much revolutionary or groundbreaking, but more like a squashed and flattened turretless Char B1. A vehicle with a singular purpose, this was Renault’s plan for a heavily armored and mine-proof tank.

Purpose

The objective of this proposal was to improve the design of existing tanks in service to make them more resilient to crossing minefields. This would be done by means of adopting both very wide tracks and also by making them run around the outside of the hull. The tracks would be so wide that the pair of them together would occupy not less than half the width of the entire vehicle.

Side view of Renault’s Improved BattleTank. (Image has been digitally cleaned) Source: French Patent FR865243

Not only were the tracks to be extremely wide, but they were also to be very thick, with a large pitch, and feature a flange that extended over the wide edges of each link. This served to overlap and provide for a continuously moving armored belt. The drawing provided by M. Renault showed 34 links per side on the tank. The thickness of the track was actually specifically made to match the thickness of the armor on the tank and be made from steel of high hardness. Thus, M. Renault designed the tracks to be part of the actual armor of the tank. The pins connecting each of the links were also to be substantially thicker and heavier than a standard track pin and, thus, these tracks would be resistant to the explosion of any mine the vehicle would drive over.

Front view of Renault’s Improved BattleTank. (Image has been digitally cleaned). From the front, the enemy would see more track than they would tank. Source: French Patent FR865243

Suspension for this very heavyweight track would be provided by rows of rollers under the floor and rear part of the tank, with no less than 5 rollers per link. These rollers would be provided with springing in order to provide both shock absorption from a mine blast or from normal travel. An additional roller could be held slung underneath the vehicle, in the narrow space not already covered by the tracks in order to detonate mines. Thus, this vehicle as it moved forwards would clear an entire width through a minefield as it traveled.

The rollers on which the extremely heavy track would move and their vertical elastic suspension meant to provide energy absorption from any mine blast. Source: French patent FR865243

The remaining space

The tracks were extremely wide as a percentage of the width of the vehicle, wider perhaps than any other before or since. However, they were not limiting M. Renault’s tank concept. There would still be space in the hull for weaponry and M. Renault took pains to describe what he saw as an improvement over existing designs in this regard. Firstly, mounted centrally on the front in the narrow hull, would be a small ball-type mounting for a light cannon or machine gun. There was another one at the rear. There was obviously insufficient space for a turret. Even the rather small French turrets of the era would be too large and M. Renault proposed a simple cupola for the commander on top instead. In order to provide fire to the sides, another ball mount was placed almost directly above the rearmost point of contact of the track with the ground. Thus, the tank would have at least two machine guns and most likely three, with the rearmost position best suited to a machine gun and the front position to a cannon.

Inside

The large boxy interior would provide space for a powerful engine, sufficient to propel this design. M. Renault chose not to suggest any particular type or prospective power output. The engine, judging by the position of the air intakes in his drawings, would be either centrally located – something very awkward for the crew to cope with, as well as noisy and hazardous, or, more likely towards the rear, with a small access tunnel to the rear weapon position. Such a position would mean some ducting for the air intakes to get to the engine for cooling and combustion. However, it was actually divided inside, M. Renault described two chambers, an engine space and a ‘control and combat room’, meaning that, just like his famous FT design of WW1, the engine would be at least separated from the crew space. Drive from the engine to the tracks was provided by drive sprockets at the back.

Armor

M. Renault, as would be expected in a patent, provided no exact thicknesses or dimensions of parts or fittings of the design, save for the desire that the tracks be of at least equal thickness to the armor. It is hard to imagine that, in 1939, a man of M. Renault’s experience and capability would not be aware of the German 37 mm anti-tank gun and its capabilities. The British would essentially work off roughly 60 mm of armor as being necessary to protect against that gun’s armor-piercing round. The preeminent French Heavy tank of the era, the Char B1, had only 40 mm and was being improved to a 60 mm standard as the Char B1 bis. It is hard to imagine that anything less than 60 mm would be suitable for such a tank, as it would clearly have to be leading any attack, clearing the mines for following vehicles. Remembering that the tracks were to be equally armored to the hull, this would also mean that the tracks would be around 60 mm thick. Certainly, this would be sufficient to prevent the vehicle from being tracked by a regular anti-tank mine. It would also make for a rather hefty vehicle. The B1 bis was a large tank, over 6 m long, and nearly 3 m high, weighing in at around 31 tonnes. Being smaller than the B1 and bis versions, this vehicle was still carrying very heavy armor for 1939. It is hard to estimate the weight of the vehicle as being anything less than around 25 tonnes.

Plan view of Renault’s Improved BattleTank. (Image has been digitally cleaned) Source: French Patent FR865243

Crew

There was no detail provided as to the number of crewmen which would be needed for this improved tank, but a good estimate can be drawn from the details he outlines. For a start, the tank needed a commander positioned high up in the hull, using the cupola, and a driver located in the front, likely low down. A gunner, positioned higher up, could have operated the cannon. That was at least three crew, but this did not allow for anyone to operate the side or rear machine guns. However, three additional weapons did not mean three additional crew, as the rear-facing machine gun would have little real use to justify a crew member just for that. Just two additional crew might have been needed as gunners, totaling 5 people in the tank.

The Renault FZ design bears a striking similarity to the later improved tank idea in shape and in the frontal armament although it retains the suspension of the older FT. Source: Pinterest

Potential

It is hard to gauge quite what potential a turretless tank might have offered the French Army of 1940. That army already had around 4,000 tanks of various types at its disposal, including the Renault R35 (10.6 tonnes, up to 43 mm of armor, armed with a 37 mm cannon and a single machine gun), the Hotchkiss H35 (11 tonnes, up to 40 mm of armor, armed with a 37 mm cannon and a single machine gun), the venerable 6.5 tonne Renault FT (with up to just 22 mm of armor and either a 37 mm cannon or machine gun), and the impressive 28 tonne Char B1 and B1 bis (with up to 60 mm of armor, a 47 mm gun in a turret ad a 75 mm howitzer in the hull, amongst others). France was well equipped in tank terms, so anything this new and “improved” tank had to offer had to go beyond the plethora of vehicles available.

The ability to drive over a minefield was clearly advantageous in an era where many foresaw warfare returning to some semblance of what was experienced a generation earlier, with heavily protected defensive lines. Other tanks also had the ability to cross and clear minefields with rollers and mine plows designed and able to be fitted to anything from the Renault FT to the Char B and R35.

Drawings page from French Patent FR865243, showing the design of Renault’s Improved Battle Tank of 1939. Source: French Patent FR865243

Timing

The timing of M. Renault’s design was to ensure it would go nowhere. France, in company with Great Britain, had declared war on Germany on 3rd September 1939 in response to the invasion of Poland. Perhaps it was this event that spurred M. Renault to think up this design, as it was filed as an application on 21st December 1939. Six months later, however, on 5th June 1940, Operation Fall Rot (Case Red) – the invasion of France – began. At this time, M. Renault was actually in Washington D.C. at the behest of the French government to discuss plans for mass production of tanks with the Americans.

In less than three weeks, the French resistance had collapsed and, on 22nd June 1940, Marshal Petain signed an armistice with the Germans at Compiegne, bringing the invasion of France to an end. Renault’s factory at Billancourt was thus within the zone of occupation of German forces in northern France and squarely under the control of the French Vichy government – the collaborationist puppet government operating in France under German direction. Management of Renault’s factory was administered by the Germans and, whilst undoubtedly he did work under these conditions, it is hard to see what other choice he may have had in the matter.

Louis Renault, June 1940. Source: US Library of Congress

It is perhaps surprising to many that the functions of government in France still continued during this Vichy period and this patent from M. Renault is a good example of this. Despite the occupation, his patent was granted on 17th February 1941 and published on 16th May that year. Whether or not this patent might even be considered valid is perhaps debatable, given questions over the legitimacy or otherwise of the Vichy government, but it would not matter to M. Renault. The vehicle was never built or deployed, it was too late to have any utility for French forces and, although it is hard to imagine that the German occupiers would not have seen it, they took no action either.

M. Renault died on 24th October 1944, just weeks after his incarceration in the prison at Fresnes, Val-de-Marne, south of Paris, awaiting trial for alleged crimes of collaborating with the Germans. This patent, like many others filed during this Vichy period, were filed and forgotten.

The Renault Improved Battle Tank was oddly reminiscent of WWI designs and could hardly be called an improvement. Illustration by Pavel Carpaticus, funded by our Patreon campaign.

Sources

  • French Patent FR865243 filed 21st December 1939, granted 17th February 1941, published 16th May 1941
  • Vauvallier, F. (2014). French Tanks and Armoured Vehicles 1914-1940. Histoire and Collections, Paris, France
Categories
WW2 French Projects

AEM One-Man Light Tank

ww2 French Tanks France (1930s)
Light Tank – None Built

Arguably the most important tank producer during the First World War alongside the United Kingdom, throughout the 1920 and 1930s, France enjoyed a large armor industry which was composed of a considerable number of different manufacturers and designers. These produced various quantities of prototypes as well as designs that never left the drawing board. One of those was the AEM one-man light tank proposal, a project from a lesser-known manufacturer, which never left the drawing board. This was probably a blessing, as the design for the operation of an entire armored vehicle by one crew member was not at all a viable concept.

An obscure design

The one-man light tank is one of two designs which were found in the archives of the DGA (Direction Générale de l’Armament – ENG: General Armament Direction) in Châtellerault, attributed to an obscure manufacturer known as AEM (Atelier d’Études Mécaniques – ENG: Mechanical Studies Workshop). The other sketch corresponds to another quite odd design, a two-man light tank with a particularly low turret and an articulated track design.

The other design submitted by AEM – a curious two-man tank featuring a very low turret armed with what appears to be a 13.2 mm Hotchkiss machine gun, and two articulated sets of tracks. Source: char-français

The exact date of these sketches is not known, though they are estimated to be from the 1930s. The AEM one-man tank is known by two profile sketches: one showing the vehicle as it would have looked like from the side, and an internal cutaway showing the internal arrangements. It ought to be noted that the one-man tank proposal is sometimes referred to as the “FT Bis” on the internet. This designation, however, is not at all historical and, while the arrangement of the AEM may look superficially similar to the FT, nothing suggests the one-man light tank was in any meaningful way based on Renault’s WW1 light tank.

External design

The external appearance of the AEM one-man tank. Source: DGA Châtellerault via char-français

The AEM light tank was a vehicle of very limited dimensions. Two measurements are featured on the plans which have survived up to this day: the length of the hull, 2.85 m from the front of the hull to the rear of the tail (which was similar in shape to a trench-crossing tail, but was an integral part of the hull, housing the transmission), and the height of the hull, 1.5 m. From these, the height of the turret can also be extrapolated and should be around 0.615 m without the periscope, and 0.77 m including it, giving a height of 2.115 m without the periscope and 2.27 m with it. Including the barrel, the total length of the vehicle should have been about 3.15 m.

The AEM’s turret had a conical section shape with a relatively rounded top from which a periscope stuck out. This shape meant it would likely have been quite wide for such a small vehicle, though the width of the AEM one-man tank remains unknown. This turret featured a vision port on the left side, and would most likely have had the same feature on the right.

The suspension was composed of 13 tiny road wheels, quite similar to the suspension on the much earlier and much heavier FCM 1A and FCM 2C. Two larger wheels were present at the front and rear of the suspension. The drive sprocket appeared to have been featured at the rear, alongside the transmission, while the front wheel would most likely have been a tender wheel. This suspension would be entirely covered by an armored side skirt.

The thickness of the armor which would have been protecting the vehicle is not known, though it would obviously have been very thin and would have unlikely provided protection from anything bigger than a rifle-caliber round.

Internal arrangement

The internal layout of the AEM one-man tank. Source: DGA Châtellerault via tous les blindés de l’armée française 1914-1940

The AEM tank was to be crewed by a single person. He would sit on a seemingly quite elaborate seat for a tank design, mounted just below the turret in the hull. From there, his feet would reach the clutch pedal while his head would reach in the turret. The steering was, as on most vehicles of the era, assured by two levers.

Almost certainly, the turret was armed with a machine gun. That being said, the weapon featured in the sketches does not match either the new 7.5 mm MAC 31E or the old 8 mm Hotchkiss mle 1914 machine guns. Although most of the barrel is covered by a shroud, the tip does not match with either of those designs, and neither does the pistol grip. The heavier Hotchkiss 13.2 mm mle 1930, which would have been quite ambitious in such a small vehicle, does not match either. It is quite likely the machine gun featured in the sketches was purely representative. In this case, considering the design appears to have been dated from the 1930s, the 7.5 mm MAC 31E would have been the most probable choice.

The turret did feature a sight for the machine gun, installed to its left, a periscope that stuck out from the turret’s top, and vision ports on the sides.

The engine was installed just behind the crewman’s seat. There does not appear to be any bulkhead separating the crew and engine sections of the vehicle, a quite archaic feature already after the FT had shown how much of a drastic improvement this was for crew conditions. The model, power, or fuel of this engine is not known. The transmission was installed at the rear, in what appeared similar in shape to a trench-crossing tail, but was an integral part of the AEM tank’s hull.

Conclusion – a terrible design that didn’t go anywhere

The AEM light tank is only known from two sketches. It appears to have never been seriously considered for production, as indicated by the plans not even being properly numbered. This was likely for the best. The operation of a tank, no matter how small, by a single crewman is generally doomed to fail. The amount of attention required to drive a vehicle, observe from the limited vision available from inside an armored vehicle, and operate a weapon, even a machine gun, is far too much to be the task of just one man. During the campaign of France, even two-man tanks such as the R35/40 and H35/39 proved to absolutely overwork their crews, particularly the commander. Not only that but the suspension designed of the AEM tank, seemingly inspired from WW1-era heavy tanks, would most likely not have been able to provide the tank with an adequate speed, while the tank’s tiny dimensions meant it would most likely have struggled to cross many obstacles despite the trench-crossing tail-shaped rear hull. In practice, the vehicle would have been little more than a mobile machine gun with very thin armor and mediocre mobility, while having a more than 2-meters high profile.

The AEM design would not, however, be the last one-man tank offered to the French military, despite the obvious drawbacks of such a design. As late as 1940, engineer Joseph Francois Raymon Collomp would design a one-man tank tasked with minelaying and demining operations as well as armed with a machine gun, tasked by a single crewman in an incredibly uncomfortable lying position. Thankfully, this design would not go anywhere either.

Illustration of the AEM one-man light tank, produced by Pavel ‘Carpaticus’ Alexe and funded by our Patreon campaign

Thanks to MortgageCalculator.uk for supporting the Tank Encyclopedia!

AEM one-man light tank specifications

Lenght 2.85m (without barrel), ~ 3.15m (with barrel, estimated
Height 1.5m (hull), ~2.11m (hull + turret without periscope, estimated), ~2.27m (periscope extended, estimated)
Crew 1
Suspension FCM 2C-inspired, 13 roadwheels, one tender & one sprocket wheel
Armament One machine-gun of unknown model
Optics Periscope, vision ports, machine-gun sight

Sources

Tous les blindés de l’armée française 1914-1940 – Francois Vauvillier – Histoire & Collection editions, p.37
Char-français: http://www.chars-francais.net/2015/index.php/engins-blindes/chars?task=view&id=14

Categories
WW2 French Projects

AMX 40

ww2 French Tanks France (1940)
Cavalry Tank – None Built

The Char de Bataille AMX 40 modèle 1940, more famously known as simply the AMX 40, is one of the numerous French tank designs which were created in the 1930s and 1940s, but never went past the drawing board, either due to not garnering enough interest, or the unfortunate interruption caused by France’s military woes in 1940. AMX’s cavalry tank project is arguably one of the most famous of those designs, largely due to its appearance and distinct look in a popular video game.

Christie and Cruiser influences

One of the most important trends in worldwide 1930s tank design was the Christie suspension. This system made use of very large road wheels which moved vertically on bell cranks. One of its main advantages was that it enabled very high speeds in tanks and potentially allowed for convertible drive, which allowed the tracks to be removed. Christie-type suspensions were experimented on by a variety of designers in the 1930s, the British and Soviets being the most extensive users of the system with tanks such as the BT-2, BT-5, BT-7, Cruiser A13 Mark I and Mark II.

France was not one of the first countries to experiment with Christie designs, mostly due to French tank designers preferring suspensions which enabled greater cross-road capacities, even at the expense of speed. Nonetheless, Christie suspensions were considered to an extent. A Christie chassis is known to have been trialed in front of the Commission de Vincennes in March of 1938. Later, in April of 1939, there were some exchanges between the French and British technical services, including on the subjects of tanks. Some of the more modern British tanks of the time were the A13 Mark I and Mark II cruisers. Those designs, using Christie-type suspensions, offered faster maximum speeds than French cavalry tanks designs, with 48 km/h. The only French tracked vehicles that offered a better maximum speed at the time were the AMR 33 or AMR 35 reconnaissance light tanks/tracked armored cars, which could only bring to bear a 7.5 mm or 13.2 mm machine gun in a one-man turret, while the A13s featured the potent 2-Pounder 40 mm anti-tank gun in a 3-man turret. Those designs had some considerable influence on Joseph Molinié, chief engineer of the fairly young AMX design bureau, a state-owned tank manufacturer born out of the nationalization of Renault’s tank producing services in 1936.

The AMX 40 project

The influence of the Christie and Cruiser designs pushed the AMX design bureau to make plans for a vehicle that combined these features with some more commonly found in French, but not British designs, such as, notably, a cast construction. The result was the AMX 40, a design presented on 4th March 1940, which could be summed up as the meeting between the British Cruiser tank concept and French industrial techniques. AMX hoped the proposal could potentially become a replacement for the S35/S40 cavalry tanks manufactured by Somua & cie, a subsidiary of Schneider.

Basic characteristics

The AMX 40 proposal was a 16-ton cavalry tank, which featured a 3-man crew, a commander/gunner and a loader in a 2-man ovoid turret, and a driver in a centrally placed driving post. The vehicle would have had a length of 5.33 meters, a width of 2.45 m, and a height of 2.37 m (1.58 m without the turret). The hull, without the suspension, was 2.03 m wide. The vehicle made use of cast construction and featured, as main armament, the 47 mm SA 35 anti-tank gun, featured in a large variety of French tanks of the late 30s, such as the Somua S35 and S40, the B1 Bis, or the second production run of the Renault D2.

Hull design

The AMX 40’s hull used cast construction. In comparison to most other tanks of the era, it had a much rounder shape, which was interrupted by the central driving post. This post featured a large openable hatch, which could be opened to provide vision when outside of combat. In combat, three episcopes, one in the center and one on each side, would provide vision for the driver. To his right was the ammunition stowage for 7.5 mm drum magazines, and to his left batteries and storage.

A top view of the AMX 40’s hull arrangement; the driver sat in a central driving post, in front of the ovoid turret. Source: Archives de l’Armement, Châtellerault

The tank would have been steered via a steering wheel. One of the various unusual features of the AMX 40 would have been a Robin-Van Roggen continuously variable transmission, an automatic transmission system without individual gears. This transmission was installed on the rear left of the hull, behind the engine. The AMX 40 was, as designed, powered by a 4-cylinder Diesel Aster engine which produced 160 hp at 2,000 rounds per minute, though a larger and more powerful Aster Diesel which had 6-cylinders and would produce 220 hp was considered to replace this first engine. This engine was also installed on the hull’s left-side, with the air filter and radiator on its right; to the right of the transmission, was the tank for engine oil. The exhaust was on the transmission’s left.

A cutaway view of the AMX 40’s engine arrangement. Note the fuel tanks on the hull sides. Source: Archives de l’Armement, Châtellerault

The diesel fuel tanks of the vehicle were installed in the hull sides. As the diesel fuel used by the vehicle was less flammable than ordinary fuel, they were thought of as potentially increasing the tank’s protection to a small extent. The armor of the AMX 40’s hull was 60 mm thick at the front, 50 to 30 mm on the sides with additional 15 mm sponsons, and 40 mm at the rear. The use of cast and heavily sloped armor meant that, unless projectiles hit the driver’s post, they would strike the vehicle on sloped armor, heavily increasing the armor’s effectiveness.

The AMX 40’s fuel stowage arrangement, with diesel in the two front side fuel tanks, and engine oil in the rear one. Source: Archives de l’Armement, Châtellerault

In front of the engine compartment but behind the turret, the AMX 40 featured a radio, of which the exact model is unknown. Another very odd feature, the hull-mounted anti-aircraft machine-gun, was mounted in this area of the tank.

Suspension

The AMX 40 project featured a model of suspension based on the Christie design. At the rear of the suspension was the drive sprocket, and at the front, an idler wheel. The suspension featured four large road wheels per side, which had a diameter of 82 cm. Considering their size, there was no need for return rollers.

As with several Christie designs, the AMX 40 was meant to be able to continue operating in the event of a broken track. To this extent, the first two road wheels were driving wheels which could be rotated to an extent, while the two rear wheels were motor wheels.

Most of the suspension was protected by 15 mm-thick side skirts, which would only have left the bottom of the roadwheel, the front of the tender wheel and the rear of the drive sprocket visible.

A view of the AMX 40’s suspension design. Source: Archives de l’Armement, Châtellerault

As a cavalry/cruiser tank, the AMX 40 was planned to reach quite high speeds, with 45 to 50 km/h on-road being the goal. However, with a horsepower of just 10 hp/t with the first Aster diesel engine, whether or not such a maximum speed could be reached is quite questionable.

Turret design

A view of the AMX 40’s turret design. Source: Archives de l’Armement, Châtellerault

Like the hull, the turret of the AMX 40 had a cast construction. It had an egg-like shape, with the rounded gun mantlet sticking out at the front. This turret was meant to house two men. To the left of the gun, the gunner (who also assumed the role of commander), and to the right, the loader. They were sitting on a strap that rotated with the turret. Though a two-men turret was a quite commendable feature for French designs, which massively used ergonomically catastrophic one-man turrets in the 1930s, the small diameter of the turret ring, with just 90 cm, would likely have made this turret quite cramped.

The turret featured a hydraulic rotation system commanded by a handle in the turret. The tank for the liquid used for this system was located in the rounded top of the turret. There was a single vision source for the turret, a panoramic telescope installed on top of the turret. The two openings on the side of the turret were for the tank’s optical rangefinder. The right opening housed an optical sight which would have allowed for a field of view of 50°, whereas the left opening housed a telemetric sight which would have allowed for a field of view of 15°.

A top view of the AMX 40’s turret sight arrangement. Source: Archives de l’Armement, Châtellerault

The turret featured a 60 cm wide round hatch on the rear, which could serve to evacuate the vehicle. It may have also allowed the commander to sit on it when opened, and look out of the tank. The turret was protected by 60 mm of armor all around and, as with the hull, its cast construction made it heavily angled, which could have further increased its effective armor.

Armament and ammunition stowage

The main armament of the AMX 40 was a 47 mm SA 35 anti-tank tank installed centrally in the turret, which had a maximum depression of -14° and elevation of +18°.

The standard issue shells for the 47 mm SA 35 were the Obus de rupture modèle 1935, and the obus explosif modèle 1932, both 47×193 mmR.

The Obus de Rupture modèle 1935 was an armor-piercing capped (APC) shell. It weighed 1.62 kg, and had a muzzle velocity of 660 m/s. German testing of the shell showed an armor penetration of 40 mm at an incidence of 30° and a range of 400 m. This was far superior to the penetration capacities of the SA 34.

The Obus explosif modèle 1932 was a high-explosive (HE) shell. It weighed 1.41 kg, including 142 grams of explosives, and was fired at a muzzle velocity of 590 m/s.

A view of the 47 mm SA 35 gun used on the AMX 40 as well as B1 Bis, S35 and second-series D2. Source: http://www.dws-xip.pl/encyklopedia/brpoj47sa35-fr/

The AMX 40 also featured a coaxial machine gun, which, as with the vast majority of French tanks of the era, was a MAC 31E machine gun. It used the standard 7.5×54 mm French cartridge. The MAC31 Type E had a weight of 11.18 kg empty and 18.48 kg with a fully loaded magazine, those being 150-rounds drums. The machine gun was gas-fed and had a maximum cyclic rate of fire of 750 rounds per minute. It had a muzzle velocity of 775 m/s.

The AMX 40’s hull-mounted anti-aircraft machine gun, of very questionable practical use. Source: Archives de l’Armement, Châtellerault

One of the vehicle’s odder features, a retractable anti-aircraft 7.5 mm machine gun, most likely the MAC 31E, though the MAC 34 aircraft machine gun is sometimes mentioned instead, was also placed behind the turret. This machine gun would emerge behind the turret, and be used against aircraft to the rear of the vehicle. Though it did feature an anti-air sight, the usefulness of this machine gun in practice is very much questionable: its firing arc was to the rear only, and to operate it, one of the three crewmen would have to leave his post. Though an anti-aircraft mounted on the top of the turret would most likely have been far more effective, with no hatch on top of the turret, this would not have been practical either.

A top view of the AMX 40’s internal arrangement, showing the 47 mm ammunition stowage in the periphery of the turret. To its rear, the two 36-rounds racks, to its front in the center, the collapsing 30-rounds rack, and on the sides, the two 10-rounds racks. Source: Source: Archives de l’Armement, Châtellerault

The AMX 40 had two circular racks for 36 rounds each on each side of the hull, behind the turret and in front of the radio and anti-aircraft machine gun. Another ammunition rack for 30 rounds was located just behind the driver’s seat and could be collapsed for easier access from the turret. Two small racks of 10 shells each were located in the hull, in front of the turret, and to the sides of the collapsing rack. This gave the vehicle a total 47 mm ammunition stowage of 122 rounds, none of which were stored within the turret itself.

As for 7.5 mm ammunition stowage, 4 150-round drum magazines were present in the turret, on the side, and to the front of it. In the hull, to the right of the driver, was a rotating chain mechanism that could contain 30 drum magazines. This chain would be rotated as magazines were taken from it, in theory allowing for constant access to new magazines, though the need for such a system was questionable. With 34 150-rounds drum magazines carried, the AMX 40 had 5,100 7.5 mm cartridges at its disposal.

A project which did not go anywhere

The AMX 40 is often said to have been planned as the replacement to the Somua S35 and S40 tanks. This statement ought to be tempered to an extent. It is quite clear that, with the design of a cavalry tank such as the AMX 40, the state-owned tank manufacturer wanted to compete with the privately-owned Somua to provide a cavalry tank for the French Army. However, the AMX 40 was presented in March of 1940, mere months before the fall of France, and by June of 1940, it appears the project was still far from being considered for prototype production. The fall of France would result in a large number of projects being canceled, though the design of new French armored vehicles would continue both openly and covertly, with vehicles such as the Panhard 178 CDM, CDM Armored Car or SARL 42 on the covert side, or improvements of the Somua S40 on the more official side.

The plans of the AMX 40, the main source of information on the project. Source: Archives de l’Armement, Châtellerault.

Errors with the AMX 40 in World of Tanks

As it is, the AMX 40 was a short-lived cavalry tank project which, while it did include some unusual and interesting features, did not go anywhere near even prototype production, and as such would most likely have remained fairly ignored. This, however, changed drastically when Wargaming’s popular online game World of Tanks (WoT) added French tanks as part of its 7.1 update in January of 2012, with the selection of vehicles added including the obscure AMX cavalry tank project.

An old screenshot of the AMX 40 as the players unlocks it: armed with the ahistorical 47 mm SA 34 gun. Source: http://forum.worldoftanks.com/index.php?/topic/559188-lets-argue/page__st__20

The AMX 40, as it is featured in WoT, is in several ways inaccurate. When first unlocked, while the vehicle features its original turret, it is armed with the 47 mm SA 34, a much less potent predecessor to the SA 35, which was mounted in several tanks of the mid-1930s, such as the B1 or first series D2, but was long out of consideration for any new designs years before 1940. The historically accurate 47 mm SA 35 can then be researched. In-game, the armament of the AMX 40 can be upgraded even further though. The original ovoid turret design can be replaced by a new turret that the game calls the “Renault Balland”. This is, in fact, the turret design of the Renault G1R, a medium tank project which reached the mock-up stage, and of which a prototype was to be assembled in the summer of 1940. This turret, however, was a very particular design. The gun mount’s weight was laid on the hull itself, with the mount going to the bottom of the hull, its weight not laying on the turret itself. It is unlikely such an unusual turret design could have been fitted on the AMX 40 without extensive modifications. This is even more noticeable due to the fact that this turret is simply too large for the AMX 40 hull, with some considerable overhang on the side of the driver compartment. When first unlocked, this turret mounts the 47 mm SA 35, though it can later be armed with a 75 mm gun called the “SA 32”. While the turret does follow the historical path of the G1R turret, with evolved from a 47 mm to a 75 mm main armament (as well as from a two-machine gun to a one machine gun commander cupola), the use of the “SA 32” designation for a 75 mm gun is questionable.

The “Renault-Balland” turret with the 75 mm “SA 32” gun. This screenshot is from an older version, the gun having since been modified to look more similar to its appearance on the actual G1R turret mock-up. Source: https://www.youtube.com/watch?v=g-x6K-iIxUE
The new look of the 75mm-armed AMX 40 since update 9.22, with a gun more truthful to the actual G1R, though whether or not its turret could have been mounted on the AMX 40 is highly questionable at the very least. Source: https://thearmoredpatrol.com/2018/01/11/amx-40-coming-to-hd-in-patch-9-22/
The actual G1R design with the turret that Wargaming mounted on the AMX 40. Source: char-français

Among other inaccuracies present in WoT’s AMX 40 is the engine. The Aster engine the vehicle starts with produces 150 hp, instead of 160 hp. While a historical option for an engine upgrade, the only historically accurate potential upgrade for the AMX 40, exists in the form of the 220 hp Aster engine, Wargaming instead went with a 190 hp “Somua LM” engine. In-game, the AMX 40’s poor engine power translates to very poor mobility, with the tank struggling to reach 20 km/h on even ground. Though the 45/50 km/h maximum speed hoped by its designer was certainly optimistic, this remains a surprisingly low speed for a tank meant for cavalry duties.

Conclusion – an obscure project rendered famous by gaming

The AMX 40 is, as it was historically, a fairly obscure project, which only existed for three months, and as such never really went far at all in its development. It did feature a considerable number of odd and sometimes innovative features. Its cast construction took the general lack of hard angles and use of sloped surfaces on French vehicles to a new level, and its two-man turret was quite significant for a French cavalry tank below 20 tons, though by the time the tank would realistically have entered service if adopted, in 1941 or even 1942, its armament would most likely have been quite lackluster, and the hull’s ability to mount a larger turret was doubtful due to its design.

The vehicle entered a second life due to its introduction in the popular video game WoT, being generally laughed at, though at the same time viewed with affection by the community. This newly-found relevance of the vehicle may also make it confusing, as another project which went much further bears the name of AMX-40 – a major evolution of the AMX-30 MBT offered as an export tank in the 1980s, mounting a 120 mm gun and many system which are now featured in the Leclerc. Though a prototype of the modern AMX-40 remains in Saumur, all that has survived of the WW2 project are the plans.

Illustration of the AMX 40, created by Pavel ‘Carpaticus’ Alexe and funded by our Patreon campaign

AMX 40 specifications

Dimensions (l x w x h) 5.33 x 2.44 x 2.37 m
Hull width without suspension 2.03 m
Weight 16,000kg (estimated)
Engine Aster 4-cylinders diesel producing 160hp at 2,000 rpm; Aster 6-cylinders diesel producing 220 hp considered.
Maximum speed 45 to 50 km/h (estimated)
Power-to-weight ratio (in hp/ton) 10 (Aster 160hp)
Transmission Robin Van Roggen continuously variable transmission
Fuel Tanks 400 liters
Average hourly fuel consumption 17 liters per hour
Range < 500km
Suspension Christie
Crew 3 men (Commander/gunner, loader, driver )
Armament 47 mm SA 35 main gun (122 rounds), coaxial MAC 31E machine gun, hull-mounted MAC 31E or MAC 34 anti-aircraft machine gun (5,100 7.5 mm rounds)
Optics Panoramic telescope, telemetric & optical sight (turret); episcopes (hull)
Armor 60 mm on the turret & hull front, 50 to 30 + 15 mm on the hull sides, 40 mm on the hull rear

Sources

Tous les blindés de l’armée Française 1914-1940, Histoire & Collection editions, p 118
Char-français
Plans from the Archives de l’Armement via mémoire des hommes

Categories
WW2 French Projects

Collomp 1 to 2-Man Tank

ww2 French Tanks France (1940-1941)
Light Tank – None Built

France has a long history of scientific, technical, military, and cultural achievements. They also have a particularly important place in the evolution of the modern armored vehicle, and in 1940, was the predominant armored power in Europe. A series of well designed and well-protected tanks, such as the Char B1, made up the mainstay of the French armor, forming a potent foe to a potential adversary. In 1940, this was obviously Germany, as France, along with Great Britain, had declared war on Germany in September 1939 following the invasion of Poland. The armored might of France was a serious threat to German plans for the invasion of France, but whilst the Char B had an abundance of armor, there were also designs which, perhaps thankfully, never made it to battle. One of these was from the pen of Joseph Francois Raymon Collomp of Marseilles, and his design for a tiny individual one-man tank was seriously and fundamentally flawed in both concept and design. It never saw action and, whilst even the mighty Char B1 succumbed to the Germans in 1940, the Collomp individual tank succumbed to common sense and was thankfully forgotten in the chaos following the fall of France.

Logic

Collomp started his design ideas with a single piece of logic: the large and modern French tanks were ideal for the large battles, striking deep within enemy territory, but were unsuitable for small actions. These ‘small’ actions would include reconnaissance work, minefield clearance, and providing supporting fire for advancing infantry. In order to reduce losses amongst the infantry forces, Collomp followed the same mental route of many others and conceived of a small armored vehicle capable of protecting the men from small arms fire. Just like those other ideas from ‘push shields’ in WW1, the Italian MIAS, or some hilariously poor ideas from General Martel in Britain, Collomp’s ideas were seriously flawed. He completely ignored the existence of a large number of small tanks already in service in France, including the Hotchkiss H35, Renault R35, and even the rather ancient and obsolete Renault FT from WW1. Instead of considering the use of a vehicle in service, his proposal was unlike anything in use at the time and smaller than any vehicle in service, not much larger than a bathtub, and of about the same combat value.

Internal view of Collomp’s one-man tank design of 1940. The area marked ‘16’ was the hatch to lay mines or charges and the area ‘B’ at the back was the electric motor. The items marked ‘14’ are control switches. Source: French Patent FR867026(A)

The Design

Submitted on 8th January 1940, the design was filed after the declaration of war against Germany but prior to the Battle of France. Overall, the design was a single large ‘cigar’ shape with two tracks running completely around the circumference of the vehicle from front to back. The front and back of the vehicle were curved and the profile was extremely low, as the occupant/s would have to lie prone inside the vehicle on a mattress facing forwards. Operating a forward facing automatic gun (presumably a machine gun), the soldier inside would be in a cripplingly uncomfortable position, especially over rough terrain as the vehicle moved and would be unable to reposition themselves without leaving the limited protection the armor offered.
Just to add an unnecessary layer of complexity to the design, Collomp suggested the addition of both mine-laying and mine-clearing equipment, although the diagram provided with Collomp’s design shows only a single roller held by two arms coming from the vehicle. Presumably, this roller was intended to roll-over and detonate mines, but this would mean it would require a certain amount of mass to simulate a tank and this then adds a weight burden to this tiny machine. All of this weight, the man/men (crew), weapons, steel armor, and now mine roller was to be propelled silently and Collomp planned for an electric motor, adding yet more complexity to the vehicle.
No armor thickness was specified, although, to provide any useful protection from small arms fire, it would need at least 6 mm of protection. Likewise, no performance in terms of speed or range was specified either.
A small hatch was fitted in the front through which the occupant could directly access the soil to lay a mine, although this clearly meant he would have to carry landmines in the vehicle with him. With no space inside in which to turn, this would involve having to drive around laying with his face next to one or more landmines, which is unlikely to have been a popular concept, particularly when facing enemy fire.

External view of Collomp’s one-man tank design of 1940. The area marked ‘6’ was the large hatch on the left-hand side (another was on the right) for access/egress. Of note are the arms and roller for the clearance of landmines. Source: French Patent FR867026(A)

Layout

This diminutive vehicle was planned by Collomp to be just 2.20 m long which, with an estimated length of perhaps 1.70 m allowed for the crew, would mean just 50 cm or so in which to accommodate the electric motor and drives for the tracks. The entire affair was supposed to be not more than 50 cm from the ground to the top of the vehicle which, accounting for the space for the man/men inside, would leave very little ground clearance, meaning the vehicle would get stuck on almost any rock or tree-stump. Further, this very low height would also mean that the crew would barely be able to see over any obstacle, bank, or even long grass.
The tracks, running circumferentially, were fitted with drive wheels at the back and a series of small support rollers around the outside on which the track could run. No information was provided as to how the machine was meant to be steered other than steering switches, which likely meant the ability to vary the driving force delivered to each track causing it to turn. One notable feature though of value for the design was the thought of adding a large hatch in each side of the tank. This meant that, in order to get in or out the soldier would not have to be exposed to enemy fire at all and that, should it overturn, it was so light the soldier could simply right it himself having clambered out the other side.

Top view of Collomp’s one-man tank design of 1940 showing the roller for the clearance of landmines. Source: French Patent FR867026(A)


Illustration of the Collomp 1 to 2-man tank by Mr. C. Ryan, funded by our Patreon Campaign.


Crew

The patent drawings show just a single occupant lying prone on a mattress inside, but Collomp specifically mentions that the design could be made wider in order to accommodate a second crewman. This wider version would be even more limited than the single vehicle, as it would still have the same ground clearance but an even greater space between the tracks, making it even less able to traverse even very slight undulations in the ground. The purpose to which this second crew member might be put is not elaborated.
Obviously, a one-man version would leave the hapless soldier the burden of driving (with no indication of how to steer) and firing the weapon, but how this would be divided as tasks for two-men is unknown.

Front view of Collomp’s one-man tank design of 1940 showing the narrow field of fire or vision which would be available to the crew and also the incredibly low ground clearance. Source: French Patent FR867026(A)

Conclusion

The design is awful. For 1940, when there was already a substantial body of tank design work in the public domain, such issues as those created by Collomp’s design should have been both obvious and avoidable. His logic was clear and so was what he was intending in terms of saving the lives of soldiers, but what he created was little more than a premade coffin in which a soldier could became trapped in the mud or on an obstacle or drown in a shallow puddle. With little or no combat value due to no visibility, the vehicle could add nothing to an attack and it is therefore perhaps ironic that the mine clearing suggestion (albeit ignoring the roller) might have been the only realistic use to which the design could have been put. Operating in a straight line through a minefield, the occupant would have easy control and a comfortable lying position without having to tire himself out by crawling and be able to access the dirt in front of him through that hatch to probe for mines and defuse them. Add a mine-tape marker dispenser to the back to show a clear lane through a minefield and this vehicle might have had some utility but, as it was laid out, it is no surprise it saw no production or orders. Whether or not Collomb submitted his design to the military authorities is not known but, with such obvious problems, there was no likelihood that this would ever be added to the Army’s inventory.
If it is any consolation to Collomp, his idea was not even the last of such ‘one-man-prone-tanks’ or even the worst one, but it remains a terrible idea and one which, had it have been in place for 1940, would have added absolutely nothing to the defence of France except perhaps for providing a lot more scrap metal for the Germans. Considering it was submitted in January 1940 though, there would have been no time to have it in time for the Battle of France in May 1940, but it does lay within this ‘Phoney War’ period between the declaration of war and the invasion of France. Almost exactly one year after the fall of France, in June 1941, the patent application from Collomb was accepted by the French patent office under the Vichy Government. It was formally published two and a half months later on 3rd September 1941. A month later, a second patent from Collomp was published for a rotating-cylinder type rifle. He had submitted that one in June 1940, during the Battle for France and whilst that design had more technical merit than his individual tank, it too found no production. What became of Monsieur Collomp is not known.

Collomp’s rotating-cylinder magazine rifle design on 1940. Source: French Patent FR867337(A)

Specifications

Dimensions (L-W-H) 2.2 x .50 x ~.50 meters (1 man), ~1m wide (two man)
Crew 1 man (second crew optional in a wider vehicle)
Propulsion electric motor – 12 accumulators
Armament Light Automatic Weapon
Armor steel, thickness N/A, est. > 6mm
Total Production None

Sources

French Patent FR867026(A) ‘Chenilette Individuelle’ submitted 8th January 1940. Patent issued 3rd September 1941.
French Patent FR867337(A) Fusil et autres armes de guerre alimentes en munitions par distributeur rotatif submitted 14th June 1940. Patent issued 13th October 1941.