Already at the very beginning of the First World War, it became clear that one of the main features of this conflict would be the widest use of various obstacles that impede the passage of enemy infantry. As a result, the countries participating in the war had to start creating means to overcome existing obstacles. Perhaps the main result of such work was the appearance of tanks. Nevertheless, in order to solve the existing problems, other types of equipment were also developed. So, at the end of 1914 in France, work began on a special Appareil Boirault machine.
The need to create self-propelled vehicles capable of overcoming various obstacles and carrying weapons became apparent in the first months of the war. However, the current level of development of science and technology did not yet allow creating the required machines from scratch. There were no even basic ideas that could be used in new projects. Because of this, the engineers of the leading countries had to independently study the existing problem, look for a solution for it, and then develop ready-made equipment samples corresponding to the solution found.
General view of the Appareil Boirault machine during testing, left side view. Photo Landships.info
In December 1914, designer Louis Boirot turned to the French military department. Studying the problems of cross-country self-propelled vehicles, he formed the original look of such a machine, which could be used to create a full-fledged project for rearming the army. At that time, France had not yet conducted a full-fledged development of armored vehicles of new classes, which is why L. Boirot's proposal could interest officials. Already on January 3, 1915, the military department approved the continuation of work on the project. In the foreseeable future, the inventor had to submit a complete set of design documentation and a prototype of a promising military vehicle.
The new project has received a very simple name Appareil Boirault - "Boirot Device". Later, when, in accordance with the requirements of the military, a new version of the project was created, the first version of the special equipment received an additional number designation. The "device" of the 1915 model was now to be referred to as # 1. The next sample, respectively, was named Appareil Boirault # 2.
The project of L. Boirot proposed the construction of a special engineering vehicle capable of making passages in non-explosive obstacles of the enemy. The original design in theory allowed this model to move around the battlefield without having problems with trenches, craters and other characteristic features of the "lunar landscape" of the First World War. Having reached the wire or other obstacles in front of the enemy's positions, the car had to simply crush them with its weight. Continuing forward, the "Boirot Device" left behind a relatively wide passage, which could be used by the advancing soldiers.
The principle of overcoming obstacles. Drawing by Wikimedia Commons
The project was based on the principle of a caterpillar propeller, modified in accordance with the original ideas of the inventor. Monsieur Boirot proposed to increase the size of the track to the maximum possible limits, and place the machine itself inside it. Thanks to this, the promising machine could have the maximum possible supporting surface, which, first of all, should have affected the width of the passage being made and the overall efficiency of the work. It is noteworthy that the design of the propulsion device was still reasonably simplified and consisted of a relatively small number of parts. So, as part of the "caterpillar" it was proposed to use only six "tracks" of a large size.
The largest and, as a result, the most noticeable element of the Appareil Boirault No. 1 was supposed to be a propulsion device based on the caterpillar principle. As conceived by L. Boirot, it was supposed to consist of six identical sections, interconnected by means of hinges. The design of the entire propeller assembly allowed the sections to swing relative to each other within certain sectors. To exclude incorrect movement of the sections, which could damage the machine, the propeller was equipped with a set of special stops.
Each section of the propeller was a metal frame 3 m wide (relative to the machine) and 4 m long. The main frame elements were a pair of longitudinal metal profiles connected to four transverse beams. For greater strength, the corners of the frame were reinforced with kerchiefs. Two crossbeams were part of the outer contour of the frame, while the other two were placed in its middle part. The extreme transverse beams were equipped with hinge elements connecting adjacent sections. On the inside of the frame, it was proposed to install a pair of rails. Next to them, but on the edge of the frame, there were two pairs of inclined stops, retracted in different directions.
The machine is in the parking position. Photo Wikimedia Commons
The assembled propeller designed by L. Boirot looked as follows. On the support surface, with the stops upwards, two sections were supposed to lie. Two more, connected to the first, were located vertically. A third pair of sections formed the "roof" of this box-like structure. Due to the hinges, the frame sections could move in a vertical plane. To exclude incorrect positions of the sections, which could lead to damage to their design, paired stops were used. When the angle between adjacent sections was reduced to the minimum allowable value, these parts rested against each other, preventing the frames from continuing to move.
Inside the unusual propulsion device, a machine frame was to be placed, designed to mount the power plant and transmission. L. Boirot suggested using a unit of a fairly simple form. It was planned to assemble a structure with inclined side supports from four main and several additional metal beams. Due to the inclination of the supports and the presence of a central horizontal part, the product in profile had to resemble the letter "A". At the lower ends of the supports, a set of additional power elements was fixed, forming a kind of support platform. There were also several rollers for interaction with the rails of the "caterpillars". Similar devices were placed on top of the frame. Thus, the A-shaped unit of the machine had to roll along the rails of the sections lying on the ground, and also support the frames raised in the air.
A gasoline engine with a capacity of 80 hp was attached to the central part, the crossbar of the frame. Using a simple transmission based on gears and chains, the engine transmitted torque to the drive wheels, the functions of which were performed by the upper and rear lower rollers of the main frame. For the correct interaction with the unusual propeller, the rollers rotated in different directions: the lower ones were supposed to move the "body" of the machine forward, while the upper ones were responsible for moving the upper branch of the unusual caterpillar back.
One of six support frames. Photo Landships.info
Inside the frame with the power plant and transmission was the workplace of the only crew member. As an experimental model, the Appareil Boirault # 1 did not need a large crew. Moreover, in fact, the only task of the driver during the tests was to monitor the operation of the engine and control the speed of movement.
The use of a single "caterpillar" of an unusual design imposed some restrictions on running characteristics, primarily on maneuverability. To make turns on the lower platform of the power plant frame, lowering jacks were provided, capable of taking on part of the mass of the machine and raising one of its sides. These jacks were "attached" to an unusual technique of turning, turning maneuvering into an extraordinary procedure.
A characteristic feature of the "Boirot Device" was a clear imbalance in the proportions of the central unit with the engine and the non-standard propulsion unit. The overall dimensions of the experimental machine were determined precisely by the design of six movable frame sections, and during movement they could change within certain limits. With the vertical position of the sections located in front and behind, and the horizontal placement of all other frames, the total length of the machine was 8 m, width - 3 m, height - 4 m. Moving and changing the position of the propulsion frames, Appareil Boirault No. 1 could become longer and higher. The width, however, did not change.
Overcoming the trench. Photo Landships.info
The total mass of the engineering vehicle was determined at the level of 30 tons. Thus, the specific power was less than 2.7 hp. per ton, which did not allow counting on high running characteristics. However, in its current form, the "Boirot Device" did not need them, since it was a demonstrator of technology.
While driving, the central unit of the machine, equipped with a power plant, had to go forward along the rails of the sections of the "caterpillar" located at the bottom. Approaching the section raised in front, the unit ran into its rails and made this frame fall down and forward. At the same time, the rest of the frames were "stretched" through the upper rollers, and the rear one rose from the ground and began to move forward.
To turn in the desired direction, it was proposed to stop, lower the jack and raise the desired side of the central unit. After that, the testers had to independently turn the car to the desired angle. The design of the undercarriage and jack allowed for turning no more than 45 °. For an experimental car, this way of turning was acceptable, although with certain reservations, but in the future this problem had to be solved.
Climbing the slope. Photo Landships.info
The development of the project was completed by the end of the spring of 1915, after which the documentation was presented to military specialists. Representatives of the military department studied the proposed project and criticized it. The car was considered insufficiently fast and maneuverable. In addition, the reason for the claims was the lack of survivability on the battlefield associated with the frame structure of the vehicle. A negative review of the project appeared on May 17. On June 10, a document was released, according to which work on the Appareil Boirault project should have been stopped due to the lack of prospects.
The army refused to continue the work, but L. Boirot insisted on the further development of the project. The inventor took into account the customer's claims and corrected some of the identified deficiencies. According to the modified project, a prototype was built, which was later planned to be used in tests. The prototype was delivered to the test site at the beginning of November 1915, shortly after which checks started.
The first tests with the participation of representatives of the military department took place on November 4. Due to the proposed improvements and other features of the project, the prototype turned out to be much lighter than previously proposed. The curb weight of the experienced Appareil Boirault decreased to 9 tons. Moreover, according to some reports, the machine itself was even lighter, which is why it had to be additionally loaded with ballast.
Destruction of wire fences. Photo Network54.com
To test the experienced "Device Boirot" at one of the training grounds in France, they set up a site that simulates a battlefield. A wire fence with a depth of 8 m was deployed, trenches up to 2 m wide and a funnel with a diameter of 5 m. The experimental vehicle successfully overcame all these obstacles. Without much effort, she climbed over trenches and funnels, and also crushed the wire and its supports. However, due to the insufficiently powerful engine, the speed did not exceed 1.6 km / h.
Not later than the first tests, the Appareil Boirault project received the playful nickname Diplodocus militaris - "Military Diplodocus". This name perfectly reflected the main features of the engineering machine, namely low speed, sluggishness and too large dimensions. Later, after the completion of work on two projects, the French historian of military technology, Lieutenant Colonel Andre Duvignac, summing up the work of L. Boirot, noted that the nickname "Military Diplodocus" was very successful and reflected well the main features of this development. The authors of this name, according to the historian, were not only jokers, but also good judges.
On November 13, the second tests took place, during which the car again showed its advantages, and also confirmed the already identified shortcomings. Overcoming obstacles did not cause any particular problems, but the dimensions, low speed and survivability on the battlefield again became the reason for harsh criticism from the representatives of the potential customer.
Appareil Boirault makes a pass through the obstacles of a simulated enemy. Photo Landships.info
In its current form, the Appareil Boirault car did not have any real prospects. The numerous disadvantages of this design outweighed all the advantages available. As a result, the army considered it inappropriate to continue working on the development of the project, not to mention ordering the serial production of equipment. Louis Boirot was forced to stop completing the existing project. Even if the existing problems were successfully resolved, one could hardly count on a contract from the military department.
Nobody else needed a prototype was sent to storage, where it remained for some time. Later, a unique, but unpromising car was disposed of as unnecessary. Nevertheless, L. Boirot was not disappointed in his ideas and continued to work on them. The result of further work was the emergence of a new version of Appareil Boirault at number 2. This time, the designer took into account the claims and wishes of the military, thanks to which an armored engineering vehicle appeared, more suitable for use in a real battle.
