The beginning of the First World War was the reason for the intensification of work in the field of promising armored combat vehicles. A few years later, this led to the appearance of the first full-fledged tanks suitable for use in the army. The first in this area were British designers. Later, several American prototype armored vehicles were tested, including the first full-fledged tank in US history. The latter became known as the Holt Gas-Electric Tank.
The Holt Gas-Electric Tank project was preceded by a rather long and complex program of research and testing of various prototypes. For several years, a number of leading US industry organizations have been working on various issues and building experimental equipment. Holt Manufacturing Company made a significant contribution to the development of US armored vehicles. This company was engaged in the construction of agricultural and construction equipment, including tracked vehicles. The existing experience in the development of such vehicles was most actively used in the creation of new models of armored vehicles.
Modern reconstruction of the shape of the Holt Gas-Electric Tank
Initially, the experimental Holt armored vehicles were built in the simplest way. The finished tracked chassis, developed for a serial or experimental tractor, was equipped with an original armored body and means for mounting weapons. Such improvised armored vehicles showed insufficient characteristics, and thereby demonstrated the feasibility of developing a special chassis. At the beginning of 1917, it was decided to create a completely new tank on a specially designed chassis. The use of ready-made units and existing experience was not excluded, but they were only supposed to complement new ideas and solutions.
Within the framework of the new project, the designers of Holt Company proposed to use the power plant with the so-called. electric transmission. Due to limited capacity in this area, Holt was forced to seek assistance from General Electric. The development of the new project was carried out within the framework of cooperation between the two companies. Nevertheless, despite the notable contribution of General Electric, only the name Holt Company appeared in the common name of the finished tank.
The use of an internal combustion engine along with an electric transmission gave rise to the corresponding project name. The experimental armored vehicle remained in history under the name Holt Gas-Electric Tank - "Holt gasoline-electric tank". No other designations or names are known.
It was planned to create a promising armored vehicle using some ready-made parts. The main source of the aggregates was to be the serial commercial tracked tractor Holt Model 75. At the same time, the tank chassis, based on the existing aggregates, had to be distinguished by increased dimensions and a reinforced structure. Also, there should have been noticeable changes associated with the applied electric transmission.
A new armored hull was developed specifically for the Gas-Electric Tank. It was proposed to make it from rolled sheets with a thickness of 6 to 15 mm. The most powerful armor was supposed to cover the frontal and side projections. It was proposed to install the armor sheets on a frame made of profiles and fasten them with rivets. The front and central parts of the hull served as a manned fighting compartment. In the stern, at the left side, the engine compartment was located. To the right of it, a corridor was provided for access to the habitable compartment.
The frontal part of a promising tank had a wedge-shaped shape and was assembled from four parts. The upper part of the frontal unit was slightly increased in height and formed a kind of cabin. An inclined triangular sheet was attached to the frontal parts from below. The hull received vertical sides, together with a horizontal roof and bottom, forming a rectangular structure. In the center of the boards, sponsors were provided. Their front part had a large opening for a weapon mount. The central element of the sponson was located parallel to the board, the rear - at an angle to it. Instead of a single stern sheet, the hull had several separate parts. On the left, the stern was covered with a movable grille, which performed the function of protecting the radiator. To her right was a door.
The chassis of a promising tank received its own protection. As a basis for it, oblong parts of a complex shape were used, which served as supports and armored shields. So, the upper part of such a unit had a groove to support the caterpillar, and the lower one covered the road wheels. The front part of the armor piece covered the rear half of the idler wheel, while the aft leader did not have any protection.
In the aft compartment of the hull there was a four-cylinder gasoline engine of the Holt brand, which developed power up to 90 hp. This engine was connected through a simple transmission to an electric generator developed by General Electric. Electricity from the generator was fed to the control devices, after which it went to a pair of traction motors. The latter were located at the sides of the hull, at the level of its bottom. The torque was transmitted to the drive wheels using chain drives.
Due to imperfect technologies, the gasoline engine and electric motors generated excessive heat and could easily overheat. To compensate for this deficiency, the tank was equipped with an advanced liquid cooling system. Excess heat was to be transferred to the atmospheric air using a large aft radiator. In case of insufficient airflow to the radiator, the aft grille was made movable: to improve cooling, it could rise to a certain angle.
The undercarriage design was created with extensive use of the Model 75 tractor parts. Two tracked drive parts were installed on the sides of the hull, outside of its projection. The chassis had ten small road wheels on each side. The rollers were mounted on a suspension with vertical springs. In the front part of the chassis there were large idler wheels, in the stern - driving wheels. The idlers and drive wheels were lowered to the ground and increased the bearing surface. The undercarriage of the Holt Gas-Electric Tank did not have support rollers. The upper branch of the track was supposed to move along the rail formed by the upper part of the chassis beam.
The main weapon of the new tank was to be a British-designed Vickers 75-mm rifled mountain gun. Its installation was located at the junction of the two lower frontal plates and made it possible to fire within a sector of small width with limited elevation angles. Ammunition, consisting of several dozen unitary shells of various types, was to be stored in the stowage of the front of the fighting compartment.
The main artillery piece was supplemented by a pair of Browning M1917 rifle caliber machine guns. The main place for the installation of the machine gun was a movable mask in front of the sponson. At the same time, on the sides and in the stern of such protruding units, there were additional embrasures that could be used together with machine guns. Ammunition for two machine guns could consist of several thousand cartridges in canvas belts. Boxes with ribbons were proposed to be transported on the racks of the fighting compartment.
Experienced Holt Gas-Electric Tank on trials
The crew of the promising "Gasoline-electric tank" was supposed to consist of six people. According to reports, the driver and commander were located in front of the vehicle. Their workplaces were raised above the main fighting compartment, and it was for them that the small wheelhouse formed by the upper part of the hull's forehead was intended. In connection with the use of electric transmission at the driver's seat, there were instruments for monitoring the operation of the engine, as well as electrical devices. It was proposed to control the total power of the power plant by changing the operating parameters of the gasoline engine. A separate electrical panel regulated the supply of current to the traction motors. By changing the power of the electric motors, the driver could perform the necessary maneuvers.
Below the commander and the driver, two gunners were to work: the loader and the gunner. The operation of two machine guns was assigned to two shooters. In the frontal and side parts of the armored hull, a significant number of viewing slots and hatches were provided. Some of them could also serve as embrasures for small arms.
Like some other armored vehicles of its time, the Holt Gas-Electric Tank had only one door for access inside. Tankers were asked to get into their seats through the opening on the right side of the stern, passing by the engine compartment. No other hatches in the sides or roof were used.
A promising armored vehicle turned out to be quite compact. Its total length slightly exceeded 5 m. Width - 2, 76 m, height - less than 2, 4 m. Sufficiently thick armor and non-standard composition of the power plant led to an increase in combat weight up to 25, 4 tons. Specific power of the gasoline engine at level 3, 5 h.p. per ton did not allow counting on high mobility characteristics. The maximum speed on a good road did not exceed 10 km / h, the cruising range was 45-50 km.
Tank at the training ground
Development of the Holt Gas-Electric Tank project continued until the end of 1917 and culminated in obtaining a construction permit for the first prototype. By the middle of the following 1918, Holt had built a prototype tank and equipped it with a General Electric power plant. As far as is known, the tank entered the first tests without a full set of weapons. According to various sources, at that moment, at least there were no machine guns on it.
Tests of a promising armored vehicle with a gasoline-electric power plant did not take much time. In just a few weeks, it was possible to determine the main pros and cons of the design, as well as draw conclusions about its suitability for practical use. It is noteworthy that, barely reaching the test site, the Holt Gas-Electric Tank armored vehicle automatically received the honorary title of the first full-fledged tank, developed from scratch, built and put into testing by the United States. Such a title would remain with her, regardless of the results of subsequent checks.
It was quickly established that the original tank had unacceptably low mobility. Even with the connection of the 90-horsepower gasoline engine to the drive wheels through a manual transmission, one could not count on high performance. The presence of a rather complex electric transmission, which did not differ in high efficiency, further worsened the situation. In addition, the electric transmission was not reliable enough and regularly broke down.
A separate problem was the constant overheating of the power plant. The gasoline engine, generator and electric motors, together with their cooling means, were located in a closed volume of the housing with an insufficient flow of outside air. The removal of the generated heat could not be significantly improved even due to the raised feed grate. It should be noted that in a combat situation, a trip with an open stern could end in the most sad way.
The feed of the armored vehicle. Engine compartment hatch and door open for improved ventilation
Due to the imperfect power plant, the experimental tank, even on a good road, could not reach a speed of more than 9-10 km / h. On rough terrain, the speed dropped noticeably. The car climbed onto slopes or walls with great difficulty. At the same time, some of these obstacles turned out to be insurmountable for her.
The weapon system used was, on the whole, not bad. One frontal 75-mm cannon and a pair of machine guns in the onboard sponsons made it possible to attack targets in different directions, exposing the objects of the front hemisphere to the most intense shelling. However, the placement of weapons used imposed certain restrictions on their use in a combat situation. However, other armored vehicles of that time had similar weapons, and in this respect, the "Gasoline-electric tank" did not stand out much against their background.
The layout of the fighting compartment was not very convenient. The main weapon and the workplace of its crew were at a low height above the bottom of the hull, and a kind of control compartment was located directly above them. It is unlikely that such a layout of the habitable compartment could be convenient for the crew. Only the work places of the airborne shooters differed in tolerable ergonomics, however, when driving over rough terrain, they also had to endure inconveniences.
In its current form, the first American tank Holt Gas-Electric Tank had a lot of problems of various kinds, which to one degree or another hampered its operation and combat use. There were virtually no real advantages over existing armored vehicles. The only advantage of the project was the very fact of its existence. Thanks to this, the United States was able to enter a narrow circle of countries capable of independently developing and building tanks. Serial production and use of new vehicles in the army, for objective reasons, was excluded.
Holt Gas-Electric Tank climbs an obstacle
Tests of the only built "Gasoline-electric tank" took place in mid-1918 and ended in negative conclusions. The first tank of the United States was unsuccessful and of no interest to the army. In addition, the prospects of this machine have been seriously hit by new international treaties. By this time, the American military department managed to order and receive imported FT-17 and Mark V tanks of French and British production, respectively. This technique was not devoid of flaws, but it looked the best against the background of its own Gas-Electric Tank.
The first US tank remained in a single copy. The assembly of the second prototype was not planned. After the completion of the tests, the first and last Holt Gas-Electric Tank remained in storage for some time, and then went to disposal. Unfortunately for fans of early armored vehicles, now a unique vehicle can be seen only in a few surviving photographs from tests.
In the mid-tenths of the XX century, no country in the world could boast of great experience in creating the latest armored vehicles of the "tank" class. Such machines were created by trial and error, with regular testing of new ideas using prototypes of one shape or another. In fact, the Holt Gas-Electric Tank became another prototype designed for practical testing of original technical solutions. He was able to get to the test, showed the main problems of his design, and also made it possible to determine the further development of armored vehicles. In addition, the Holt Petrol-Electric Tank retained the honorary title of the first American vehicle in its class. However, numerous shortcomings did not allow it to become the first serial US tank.