Soon after the appearance of the first real British development tanks on the battlefields, an idea emerged about the need to increase the size of armored vehicles, which allowed them to strengthen their armor and use the most powerful weapons. Such "land ships" and "mobile fortresses", as it then seemed, could be of great interest to the military. However, at the same time they were an extremely difficult task for the designers. The level of development of the technology of that time still did not allow to undertake with confidence the design of large and excessively heavy combat vehicles, which, however, did not prevent the appearance of new, daring projects.
General view of the armored 200 ton Trench Destroyer
According to some information, the next project of the super-heavy combat vehicle with the most powerful gun and machine-gun armament was proposed by the specialists of the Holt Manufacturing Company. The main activity of this company was the production of agricultural and construction equipment on wheeled and tracked chassis. At the same time, its engineers several times attempted to adapt existing civilian vehicles to solve military tasks. Such an adaptation, in the first place, consisted in the development of an armored corps with equipment for mounting weapons.
The development of the original project, launched at the end of 1916, was attended by several leading experts from Holt. So, the tracked chassis was created by Pliny I. Holt and Elmer Wickersham. A significant contribution to the development of the armor hull of the original design made Stephen Kupchek. Subsequently, all engineers were able to work on a number of other military and civil projects. For example, S. Kupchek later proposed his own land ship project.
According to preliminary calculations, the future combat vehicle turned out to be uniquely large and heavy. It was proposed to use it, first of all, as a means of breaking through enemy defenses and as a mobile firing point. All this has led to the emergence of working titles that fully reveal the essence of the project - 200 ton Trench Destroyer (“200-ton trench destroyer”) and 200 ton Moving Fort (“200-ton mobile fort”). In the case of adoption of a military vehicle in service could appear a new official name.
A number of projects already created armored vehicles from the company Holt Manufacturing implied the construction of military equipment by equipping the existing chassis protected body. In the project “Destroyer of trenches” they decided to use this approach once again. However, the specific technical appearance of the future tank made special demands on the chassis used. Despite this, the designers managed to find a suitable base.
By the summer of 1914, the construction of the Panama Canal was completed, but it soon became clear that some of its sections needed to be expanded. For such works, builders could need new equipment, and this fact could not fail to attract the attention of Holt. The development of a promising heavy excavator capable of carrying large volumes of soil was launched. Especially for this car should create a new tracked chassis. In the foreseeable future, a new 60-ton excavator was supposed to be offered to builders. For obvious reasons, initially this project had an exclusively non-military purpose and was not considered as a base for combat vehicles.
Due to some technical difficulties, the development of a heavy excavator was delayed and was not completed even at the end of 1916, when the design of a promising super heavy tank began. Despite the lack of a ready-made earthmoving machine, it was decided to use its chassis in the “mobile fort” project. It was assumed that the tracked undercarriage, originally created for the 60-ton excavator, after minor modifications could become the basis for the armored vehicle, which has several times greater combat mass.
From the base chassis should remove all devices corresponding to its original purpose. Instead, it was proposed to mount a new armored corps with a set of weapons, crew jobs, etc. The high carrying capacity of the chassis allowed the use of sufficiently powerful armor. The thickness of the riveted body parts could reach 2 inches (50,8 mm). At the same time, the new building should have the simplest possible shape, formed by a large number of rectangular parts.
A characteristic feature of a number of early tanks, including the super-heavy Trench Destroyer, was the placement of all the necessary components and assemblies, as well as the crew in a single protected volume. The division of the case into compartments was not provided for, although some internal devices could be equipped with lightweight covers. The central part of the hull had to accommodate the power plant and transmission. All other volumes served as a fighting compartment and filled up with weapons to the maximum. Near weapons there were crew jobs.
According to surviving data, the 200 ton Trench Destroyer was supposed to get as simple an armored corps as possible with powerful protection. From 50-mm armor it was proposed to assemble a rectangular in plan design with several protruding units. A large rectangular frontal sheet was used, to which the vertical sides and the horizontal roof were joined. Due to certain technological limitations, the beads were to consist of several vertically oriented sheets. Behind the body there was a vertical sheet, similar to the frontal part.
On the roof of the armored vehicle should be placed a deckhouse, having devices for mounting machine guns. It is known about the development of three variants of such a unit. The first one was quite long and occupied about a third of the roof. The superstructure had vertical frontal and stern sheets, with which beveled cheekbones mated. The sides of the superstructure were placed parallel to the longitudinal axis. Above, the arrows were protected by an armored roof. The second version of the roof was distinguished by smaller longitudinal dimensions and a more dense layout. The third version of the add-on was similar to the second, but it was proposed to make it higher and place the weapon in two tiers.
It was proposed to install protruding sponsons with gun and machine-gun installations on the sides of the main building. Sponson was supposed to be an armored box that extends beyond the sides of the hull. In the front and rear parts of it was intended to install gun installations. Sponson plates should be equipped with embrasures for machine guns.
According to reports, near the center of the hull and the chassis should be located gasoline engine of sufficient power. Behind the engine was placed a mechanical transmission associated with driving wheels aft arrangement. The type and power of the proposed engine has not been determined until the very end of the work. The documentation submitted by the military, directly stated that the engine has not yet been selected.
It can be assumed that in order to achieve acceptable mobility characteristics of the 200-ton armored vehicle, a uniquely high power propulsion unit was required, perhaps even consisting of several engines. In this case, the engine was supposed to differ in small sizes that fit into the dimensions of the hull. There is reason to doubt the possibility of creating such an engine at the existing level of technology.
The basic design of the excavator assumed the use of a running gear with ten support rollers of average diameter on each side. They were planned to be mounted on longitudinal beams, five each. Beams had an elastic suspension. The front beam was supposed to get the attachment for the installation of the guide wheel of large diameter, slightly hung above the ground. The drive wheel of the same size was placed in the rear part of the chassis, but without communication with other elements of the chassis. On the rinks and wheels should be placed metal coarse track.
As a main weapon, the advanced super-heavy tank was to use six guns with a caliber 75 mm. In this capacity, it was proposed to use canon de 75, French-made modèle 1897 tools. All guns should be mounted on standardized installations with a characteristic cylindrical mask. According to one such installation it was located in the front and aft hull sheets. Also, the guns should be installed in the front and rear parts of the board sponsons.
Having such a set of gun installations, the tank could fire at targets in any direction, with the exception of some part of the side sectors. The areas of responsibility of some guns could overlap slightly. At the same time, all six guns did not have the ability to quickly transfer fire to large angles. To solve such fire missions, it was necessary to use another cannon or to deploy the entire machine as a whole.
The authors of the project were able to find a place to install 20 machine guns. Guns proposed to complement the latest Browning M1917 machine guns with water-cooled barrel. Two such machine guns were to be placed on head-mounted installations on the sides of the gun. One machine gun was placed on each board, in front of the sponson. In the stern of the boards arranged in two installations. Two more loopholes were on board each sponson. A pair of machine guns was placed on the right and left of the stern gun. The remaining six machine guns should be installed in the superstructure: one each in the forehead and stern and two each on the sides. It should be noted that the design and shape of the add-on did not affect the number of machine guns.
The project also envisaged the enhancement of the barrel weapon with the flamethrower of the Tractor Type Mark I model. In the existing protected volumes it was possible to place sufficiently large tanks for flammable liquid.
The need for simultaneous maintenance of a powerful engine (or engines), transmission, six guns and two dozen machine guns led to a remarkable increase in crew. The 200 ton Trench Destroyer / 200 ton Moving Fort was to be driven by a crew of 30 people, most of whom were gunners and machine gunners. The crew was asked to get into the tank through two doors in the stern of the sides. For observation should use numerous embrasures and inspection hatches.
Unfortunately, the exact dimensions of the proposed super-heavy tank are unknown. According to various estimates, the length of the armored car should have exceeded 10-15 m with a width of at least 3-4 m and a height of more than 3-4 m. The combat weight of the “Mobile Fort” was estimated at 180-200 t. Someone hardly doubted the impossibility obtain high mobility characteristics. Even at maximum speed, a promising machine could hardly overtake an infantryman, both on a good road and on rough terrain.
Two options for cutting-superstructure with a different location of weapons
The 200 ton Trench Destroyer project was completed in 1917, and soon the documentation was submitted to the US military. An analysis of the original project was entrusted to Army Officer George Smith Patton. In his diaries, J. Patton wrote that the name “mobile fort” did not fit the Holt Manufacturing tank. It should have been used in relation to another super-heavy armored vehicle with a mass of 1500 t, presented at the same time. In addition, the officer noted that the 200-ton tank was outwardly similar to the German A7V, but at the same time it was twice as large and heavier.
Thanks to J. Patton, it is known that Holt was planning to build a prototype in the near future and test it at American test sites. In the summer of the next 1918, the “Trench Destroyer” was supposed to be sent to France for testing in the military. At the same time, the officer noted that a large mass of combat would lead to unpleasant consequences: the tank would get to the place of the future battle for an extremely long time.
In general, the officer’s findings were negative. As a result, the original project did not receive the support of the armed forces and therefore lost all chances for further implementation. Holt was interested in receiving military orders, but building a large, complex and expensive prototype vehicle at its own expense was not part of its plans. Thus, after the refusal of the military, an unusual project 200 ton Moving Fort / 200 ton Trench Destroyer was closed for lack of real prospects. By the time such a decision was made, the tank existed only on the drawings, whereas in the company's workshops the construction of an experimental chassis for the future excavator was carried out.
At the time of the creation of the “200-ton trench destroyer,” the American army had no experience in operating armored combat vehicles in the context of a modern war against a well-equipped enemy. Nevertheless, even in such conditions, the command was able to objectively evaluate a number of new projects, including promising super-heavy tanks. Despite the lack of experience in this area, the officers were able to find and identify all the characteristic flaws of such equipment and prevent unnecessary spending on unpromising projects.
It is easy to see that the construction of the Holt 200 ton Trench Destroyer tank and now - with the modern development of technology and technology - would not be the easiest task. By the standards of the tenth years of the last century, the mass production of such combat vehicles in general turned out to be impossible. In particular, one of the unsolved problems of the project was the choice of the power plant, which required maximum power with minimum dimensions. Adapting the chassis of an 60-tonne excavator for use as the basis for an 200-tonne tank would also prove to be a very difficult task.
The operation of a super heavy armored vehicle would be associated with many difficulties and minimal positive results. The crew of the 30 people only with great difficulty could fit in the existing body, partially occupied by the power plant and weapons. Low mobility would lead to serious restrictions on the transfer and combat use of technology. Finally, a large inactive tank would be a priority target for enemy artillery. Even 2-inch armor could not save from the fire of large-caliber guns.
Understanding the lack of real prospects and the existence of a mass of problems of various kinds, the American command prudently abandoned the Trench Destroyer project. He did not even bring to the construction and testing of a prototype. A similar fate befell a number of other developments in the field of extra-heavy armored vehicles. Despite the apparent advantages, this technique had no real prospects. As a result, the tank 200 ton Trench Destroyer added to the list of useless searchlights, rejected by the army. Later the same thing happened with several other developments.
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