At the end of 1910, a political crisis began in Mexico, culminating in a change of power and civil war. Over the next few years, various political forces supported by armed groups tried to take power into their own hands. In addition, some groups often invaded the territory of the neighboring United States and attacked local settlements. The US Army tried to fight such raids, however, despite all the successes in this matter, the attacks did not cease. It was obvious that some new tools were needed to solve the existing problem.
In 1915, the Holt Manufacturing Company offered its solution to the problem of raids, building various tractors and working on various versions of promising combat vehicles. As planned by the firm’s specialists, self-propelled vehicles were required to more effectively combat the trespassers of the army. It was proposed to ensure superiority over the enemy with the help of thick armor and sufficiently powerful artillery weapons. At the same time, in the new project it was possible to use a number of existing developments in other equipment, while separate units and units would have to be created from scratch.
Reconstruction of the image of the machine Holt 150 ton Field Monitor
The future armored vehicle was planned to be used in the southern regions of the United States, distinguished by its characteristic landscape. In addition, during the pursuit of the enemy did not exclude the possibility of crossing the border with access to similar areas belonging to Mexico. The features of the intended combat use made it possible to significantly simplify the technical appearance of the future machine. Sufficiently strong soils of the southern regions allowed the use of a wheel propulsion, providing the required characteristics of maneuverability and mobility.
Elaboration of the technical appearance of the future armored vehicle led to very interesting results. It turned out that obtaining optimal performance will lead to an increase in size and combat weight. The last parameter was to reach the level of 150 tons. The presence of armor and a developed armament complex forced us to recall the ships of the “monitor” class. For these reasons, the original combat armored vehicle project was officially called the Holt 150 ton Field Monitor (Holt's 150-ton Field Monitor). In the case of the successful completion of the project and the adoption of the machine could get one or another official army name, but this did not happen.
A promising combat vehicle had to be distinguished by a uniquely large mass, which, above all, was related to the level of protection. On the basis of the remaining data, from a certain point in the “monitor” project, the possibility of using reservations from 24 to 75 mm was considered. It is curious that in some sources the same numbers are indicated, but measurements are given in inches. However, 75-inch armor (1905 mm) looks implausible and is clearly the result of an error in units of measurement.
Armor thickness of not less than an inch would allow the machine to confidently withstand hitting bullets and fragments, as well as protect the crew from small and medium caliber artillery. In connection with the level of development of technology at that time, armor parts were to be assembled into a single structure using a frame of the required shape and various fasteners.
According to reports, the project 150 ton Field Monitor offered the construction of an armored corps of a rather complex shape, formed by a large number of rectangular or beveled panels. In terms of the body should have a shape close to rectangular. With the horizontal bottom should match the vertical side, consisting of a large number of individual parts. In the center of the sides projected sponsons were provided. The frontal projection of the case was covered with a vertical bottom sheet, over which a more complex structure was placed. In the center of the top of the forehead there was a triangular protrusion, on the sides of which it was proposed to place a pair of gun mounts with cylindrical movable masks.
Behind the gun mounts there was a large superstructure that occupied about half of the total length of the hull. The superstructure had a vertical stern leaf, connected to the horizontal roof of the aft compartment. The stern projection was covered with a vertical sheet of medium height.
It was proposed to equip the combat vehicle with a pair of towers of the same design with a shoulder strap with a diameter of 2 m. One of them was to be placed in front of the hull, above the gun installations. The second was located on the roof of the stern, immediately behind the superstructure. The towers had a cylindrical shape without separate front or side parts. On the horizontal round roof was proposed to provide an opening for the installation of the turret with viewing slots.
Given the high mass of combat, the authors of the project found the only suitable power plant, which could be built at that time using existing technology. Two high-power steam engines should have set in motion the 150-ton monitor. These products were developed by Holt with the active assistance of Doble engineers. The specialists of the two organizations already had experience in joint designing of steam power plants, which to some extent helped in the creation of a new armored vehicle.
According to some data, the entire aft of the hull, which was distinguished by a lower height, was given along with part of the central compartment to two steam engines of high power. Directly connected to the steam engines was the main gearbox, through which the torque was distributed to all four wheels. To obtain the maximum possible characteristics of mobility and control, it was decided to equip all-wheel drive with its own gearboxes. Because of this, as you can imagine, the 150 ton Field Monitor could do without steered steering wheels.
The undercarriage of a super-heavy combat vehicle consisted of four wheels with a diameter of 20 feet (6 m). The use of all-metal wheels was suggested. They had to have a tire assembled from a large number of metal plates. The side view of the wheel was completely closed by a disk of the corresponding sizes. The wheels had to be mounted directly on the axles of their gearboxes. The use of any depreciation systems was not intended. The turning gears are also not used; It was proposed to maneuver by changing the speed of rotation of the wheels of different sides.
In the frontal part of the body on a pair of their own installations should have been placed the main guns of the combat vehicle. As the "main caliber" it was proposed to use 6-inch (152 mm) ship-type guns of the available types. Based on overall considerations, the allowable length of the barrel is limited to 30 caliber. The possibility of using smaller-caliber artillery systems, including those with a shortened barrel, was also considered. In all cases, the design of the hull and gun mounts ensured firing within not too wide horizontal and vertical sectors. Despite the different characteristics of the guns of different models, the Field Monitor, in any case, had to show high firepower.
For the attack of enemy manpower it was proposed to immediately use the 10 machine guns Colt M1895. Two machine guns were planned to be installed in two towers. The remaining ones could be distributed among several installations in the sponsons of the corps. Thus, the machine gunners had the opportunity to control a significant part of the surrounding space. All machine guns had limited sectors of fire, but their areas of responsibility partially overlapped. The joint use of machine guns made it possible to attack targets in almost any direction.
An interesting feature of the Holt 150 ton Field Monitor project was a large crew. Manage the machine should have 20 people. The driver and two on-board engineers had to control the movement and the main systems. The operation of the guns was trusted to at least 6-8 gunners. The remaining crew members served as gunners. Crew jobs were distributed throughout the habitable volume of the hull and towers. All places had the means to monitor the terrain and target weapons. Access to the car was provided by side hatches, located under the sponsons of the case.
The total length of the future “monitor” was to reach or exceed 20 m. The width of the vehicle was within 4 m, height was no less than 7 m. reach a speed of no more than a few kilometers per hour. Cruising, limited by the availability of fuel and water, also could not be outstanding.
According to Holt Manufacturing's initial plans, the design of the 150 ton Field Monitor should be completed in the 1915 year, and then the necessary documentation should be presented to the military. In the case of a positive decision, already in 1916-m the first prototype could have entered the test site. The further fate of the most interesting project was to be determined in accordance with the wishes of the customer. It soon became clear that such plans could be implemented only partially.
Indeed, before the end of 1915, the Holt designers completed the preparation of the project, and soon a package of necessary documents was sent to the military department. Its leaders got acquainted with the unusual proposal, but were not interested in it. First of all, the Field Monitor was criticized by General John Pershing. He rightly noted that a heavy and slow machine would not be able to effectively support cavalry. The maintenance of the infantry, in turn, also could not lead to outstanding results justifying the construction of large and heavy vehicles.
The military even refused to build and test a prototype. However, the development company has not lost hope. She continued the development of the existing project, trying in one way or another to improve the main characteristics and expand the existing opportunities. For example, a complex of artillery weapons was consistently subjected to several modifications. In addition, the outdated machine guns M1895 gave way to the newest M1917. The main features of the architecture and design, however, have not changed. Probably, in some cases, the processing of certain ideas was associated with the need for a complete redesign of individual structural elements.
Armor case "monitor"
The available information suggests that as the existing project developed over several years, the Holt designers managed to rid their project of certain weaknesses and certain weaknesses. However, the updated super-heavy wheeled combat vehicle could not interest the military. It is noteworthy that by this time the US command began to prepare for entry into the war in Europe, however, it was not possible to find places for the Holt 150 ton Field Monitor at this theater of operations either. Military leaders still believed that maneuverable fighting was the task of cavalry and light armored vehicles.
After several years of work, which did not give any real results, Holt Manufacturing was forced to close a project that once seemed promising. In its original form, it did not interest the main customer in the face of the United States Army, and the subsequent modernization and improvement did not lead to the desired consequences. The project was closed, and all documentation went to the archive without any hope of returning from there.
Currently, with modern knowledge of armored vehicles, it is not so difficult to understand the reasons for abandoning the original “Field Monitor”. At one time, such a combat vehicle could not find real use for a variety of reasons. Moreover, even in later periods, the proposed technical design did not allow obtaining the desired results. First of all, the reason for the failure was the unjustified consolidation and over-weighting of the structure. A 20-meter 150-ton four-wheel drive vehicle would be too complex for construction and operation.
A big problem could be steam engines. They were able to provide an acceptable power density, but the low reliability of such a powerful power plant would seriously hinder the operation of the 150 ton Field Monitor. The proposed wheeled chassis could also lead to difficulties, for example, in overcoming these or other obstacles. In fact, all-wheel drive wheeled car without any problems would be able to drive only in relatively flat landscapes of the southern states or Mexico.
As shown by further experience in the creation of armored vehicles, self-propelled guns can carry one weapon and at the same time have high combat qualities. From this point of view, two installations with 6-inch guns that were proposed for placement on the “monitor” look redundant and unnecessarily complex. Rejecting a part of the guns or even one of the towers would lead to a considerable weight saving and corresponding advantages of a different nature.
The placement of twin machine-gun installations in rotating towers was a definite plus of the project. However, the proposed towers were too big for such weaponsthat could lead to the known difficulties of production and operational nature. The high placement of the towers could make it difficult to fire at targets that are at a short distance from the armored vehicle. Also, it should be noted that the proposed placement of machine guns left a lot of dead zones, first of all, covered with large wheels.
Thus, the proposed super-heavy combat vehicle Holt 150 ton Field Monitor had only a few noticeable advantages. First of all, she could simultaneously attack several targets with cannon and machine-gun fire without significant risks for the crew. In addition, having appeared on the battlefield, a huge machine with powerful weapons had every chance to provoke panic in the ranks of the enemy. This is where its advantages ended. All other technical and operational features were associated with a variety of problems.
In such a situation, the refusal of the military to support an unusual project does not look like something unexpected or wrong. The command sensibly reasoned and did not help in the further development of the obviously unpromising model. Holt engineers, in turn, were able to study a curious concept at a theoretical level and draw all the necessary conclusions. According to the results of the work carried out, in the next project of the military machine, the designers decided to do without overly bold proposals and significantly reduced the overall dimensions of the vehicle.
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