The green light was given to works in different directions of development of the main battle tank, but the most interesting thing was exactly the revolutionary project, which involved the creation of a new combat vehicle with a crew of only two people. In a sense, the designers tried to transfer the idea of strike aircraft to ground equipment. Very often, the crews of combat aircraft consist of exactly two people - a pilot and an armament operator. In the tank, the German designers expected to maintain the same distribution of roles - the driver-mechanic and the “armament operator”. At the same time, both crew members were to receive a sufficient set of instruments for monitoring the terrain and controls, in order to easily duplicate each other’s functions if necessary.
Reducing the crew of the tank from four to two people was to significantly reduce the reserved volume, which means the size and weight of the combat vehicle. Another idea was the use of two successive crews of two people. According to the designers, this would lead to an increase in the time of direct use of the tank, since one crew could rest while the other would be engaged in the operation of military equipment. Finally, the loss of a car in battle would mean the loss of not four trained tank crews, but only two people.

To create a new combat vehicle, whose crew would consist of just two people, it was necessary to create new ways to control various functions. Charging in the tank could be relatively easy to replace the automatic loading system. But it was already quite a challenge to combine the functions of a tank commander, driver and gunner. In fact, the crew of the tank was to consist of two commanders who themselves had to determine who would perform what functions at a particular point in time.
The project of a new tank with a crew of two people received the name VT-2000 (Versuchstrager - experimental chassis, Kampfpanzer Versuchsträger 2000). As a platform for the new tank, it was decided to use the chassis and hull of the MBT Leopard 2. And on the site of the tower, the German designers installed an experimental fighting compartment - a KSC container (Kampf system container). In the new fighting compartment were located places for two people, various sights and observation devices for the terrain were installed. Both crew members of the experimental tank had the same controls both for controlling the combat vehicle and for controlling the observation instruments and sights. Since the tank was experimental, no weapons were installed on it. In this case, the workplace of the mechanical drive was kept in the case, but only for its use by an engineer who monitors the progress of the entire experiment. All controls in place of the driver in the tank hull were blocked.
At each workplace of the crew of the experimental tank Kampfpanzer Versuchsträger 2000 monitors were placed to display information from day and night surveillance devices, as well as handwheels, levers, handles and pedals to control the tank and joysticks to control the sights. To move the tank in reverse, one of the workplaces also received additional control drives, and a member of the crew of the combat vehicle had to turn its seat 180 degrees backwards. This was done for security reasons - the tank always had to move in the direction that the mechanical drive looked. In the stern of the fighting compartment-container, a large mast was placed with numerous sensors of various instruments. It was there that independent (for the crew members of the tank) sighting systems were installed, each of them had its own laser range finder and day and night channels. Sights for each of the two crew members of the pilot tank could rotate vertically and horizontally independently of each other. Three surveillance cameras for the terrain, which the mechanic would use, were installed between the aiming complexes. For its time, this tank was distinguished by the presence of the most advanced and up-to-date navigation equipment and various crew alert systems about the tactical situation.

At the same time, the whole system was quite “raw”. The Germans did not test the prototype, but only run-in ideas, concepts of the future tank. It was a real experiment. It is no coincidence that even pneumatic was used to drive the optoelectronic modules installed on the tank. Two cylinders filled with compressed air were located behind the experimental fighting compartment and provided enough reserve for conducting various tests of the machine.
After a series of tests, the work on the creation of the German experimental tank VT-2000 was stopped. The experiment carried out clearly showed that the concept of such a tank could be used in the future and, in principle, a crew of only two people could control the tank and carry out their combat missions. However, in the current realities this was extremely difficult to achieve. Combining a number of functions and their delegation to each member of the crew of an experimental combat vehicle did not produce the necessary result. It was quite difficult, relying on the existing technical level, to control the movements of the tank and at the same time monitor the battlefield and perform combat missions. In practice, it turned out that almost always one crew member was focused on controlling the tank, and the second one was watching the battlefield, looking for targets. In this regard, there was simply no time left for command of the tank, as well as establishing interaction with other combat vehicles of the unit, adjacent units and the higher command.
To solve all these tasks and make the concept of a tank with a crew of two people workable in practice, it was necessary to maximally automate the processes of reconnaissance, identification and tracking of detected targets, as well as controlling the driving of the tank. But such technologies in those years simply did not exist. All this together with the collapse of the Soviet Union and the end of the Cold War "nullified" many military projects of those years, including the reason for the refusal of further work on the project of an experimental tank Kampfpanzer Versuchsträger 2000. Despite this, a number of systems, which, for example, were surveillance systems, were used by the military for other developments of military equipment.

The Germans themselves chose as a result an evolutionary path of development, which led to the appearance of tanks of modifications Leopard 2 A5 and Leopard 2 A6. These projects were less ambitious, but did not require significant time and money. As part of improving the combat effectiveness of the Leopard 2 main battle tank, two projects were developed: KWS I, which provided for increasing firepower without increasing the caliber of the gun and KWS II, which included increasing the security of the MBT. Work on the first project involved the creation of an upgraded 120-mm tank gun with a barrel length 55 caliber (Rh 120 L / 55) and a new armor-piercing-snapping 120-mm tank shell. The implementation of this project led to the creation of an experimental tank SVT. The resulting tests later formed the basis of the modification of the tank Leopard 2 A6. As part of the second project, elements of additional booking were created, they were used on the experimental tank “for testing components” of KVT. The results of this experiment formed the basis for the modification of the tank Leopard 2 A5.
It is worth noting that its project to create a tank with a crew of two people existed in the Soviet Union. At the beginning of the 1980-ies in the Kharkov engineering design bureau were working on the project of the main battle tank with a crew consisting of two people, it was planned to place them in the tower. To control the tank, it was planned to use a rather complicated stereoscopic television system, which was located in the forward part of the body of the combat vehicle. The work on the creation of this tank was headed by E. A. Morozov, and the tank itself was designated the “490 Object”. But due to significant technical difficulties, the matter did not reach the release of the tank “in metal”. The project has not been implemented.
Information sources:
http://naukatehnika.com/leopard-2-dlya-bundesvera.html
http://www.dogswar.ru/oryjeinaia-ekzotika/bronetehnika/8182-opytnyi-tank-vt-2000.html
https://strangernn.livejournal.com
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