Protection of the T-80U tank: mugs on the tower and rubber aprons

In the near future, the T-80U tank, which was created in the Soviet Union, will celebrate the 40th anniversary of its military service. Despite the fact that so much time has passed, one can still hear myths about the tank, such as the assertion that its rubber "body kit" in the form of an apron and mugs is necessary to enhance anti-cumulative protection. However, in fact, the reason for this design is simple - it is dust protection.

Tanks, like any complex machines, have their own "childhood illnesses", that is, shortcomings that were not taken into account during the design and which were revealed only during operation. These shortcomings are being corrected as new tanks are produced and existing ones are upgraded. However, the T-80 has one "disease" that has not been eliminated - this is the high vulnerability of the gas turbine engine when working in dusty areas, such as loess deserts or sand.

This problem is not unique to the Soviet gas turbine engine. The American Abrams tanks have a similar problem. Dust entering the power plant begins to sinter and grow on the turbine blades and in the gas path, which leads to a decrease in engine life and irregular power surges. The only way to solve this problem is enhanced air purification. However, the filter will clog much faster than in a piston engine, which consumes 4-5 times less air.

American Abrams tanks were equipped with two-stage cartridge filters that must be manually cleaned regularly. In desert conditions, this procedure should be carried out even once an hour. Soviet T-80U tanks were equipped with cassette-free maintenance-free filters to save engine-transmission volume from division and ease of operation. However, such filters did not provide sufficient air purification and passed a significant amount of dust - up to 2-3 percent.

For most regions of the USSR, including Siberia and the Far East, the air purification quality provided by cassetteless filters was sufficient for tank marches. However, tanks must operate in the harshest environments, including deserts and other areas with high levels of dust. It was in such conditions that the pre-production T-80s, which were launched even before the T-80U, experienced problems with the engine, which barely worked out a hundred engine hours, and sometimes even less. While in the eastern regions of the RSFSR this figure was 200-300 hours.

The problem of the high vulnerability of the gas turbine engine was solved only by enhanced air purification. Such filters were installed on later modifications of the T-80 and made it possible to significantly increase the engine's engine life. However, the use of such filters required high maintenance costs and increased the cost of operating the tank.

Global warming and the construction of the large Karakum Canal in the period from 1970 to 1980 had a strong impact on the state of the desert and, accordingly, on the operating conditions of T-80 tanks in this region. Due to the increase in the average air temperature, the dust layer on the tank routes has grown from 80-270 mm to half a meter in some places. This led to an increase in the dustiness of the air and increased vulnerability of the gas turbine engine of the T-80 tanks.

In addition, the Karakum Canal caused strong winds, which naturally affected the increased dust content of the air. All these factors could not but affect the operation of the T-80 turbines, which regularly made runs in this region. Something had to be done to improve the conditions for tanks in the desert.

During the production of the T-80, many improvements were introduced related to engine dust protection. These improvements include: an air intake device in the rear of the tower, which increased the height of the air intake, where there is less dust; system of vibration cleaning and engine purge with compressed air; self-cleaning nozzle filters; fan exhaust; "desert" mode with a decrease in gas temperature to prevent dust melting and much more.

However, the most interesting improvement in terms of dust protection are dust aprons and mugs. They are installed on tank tracks to prevent dust and sand from entering the gas turbine engine. While these devices do help protect the engine from dust, they have also given rise to many myths and legends associated with the T-80 tank.

Some believed that these shields had magical properties, such as the ability to reduce radar EPR, provide thermal camouflage, or even protect against projectiles. However, according to the author, these statements have no scientific justification.

In particular, rubber shields do not have sufficient rigidity and can bend under the impact of a cumulative projectile, and with a significant delay, which will only increase penetration. Moreover, there is no combined armor in the lower frontal part of the tank hull, so the presence of an apron can only worsen the situation.

At the same time, when using the T-80 tank, there was a problem of dust in the air path, since the air filter could not filter out the fine dust fraction less than 2 microns in size. These microscopic particles do not have their own mass and move only under the influence of aerodynamic forces. The author proposes to change the "streamline" of the hull and turret of the tank in order to create the necessary air turbulences that would prevent fine dust from entering the air path. This solution involves the use of aerodynamic forces to ensure that microscopic dust particles do not enter the air intake at all and enter the turbine, which would help to cope with this problem.

To test the effectiveness of the proposed methods, experiments were carried out in a TsAGI hydrodynamic tunnel GT-400 with a tank model on a scale of 1:32. It turned out that behind the tank turret, above the air intake, a low pressure zone is created, which draws in dust flows. Dust mainly moves in three directions: through the bottom of the tank with a swirl to the stern, along the undercarriage along the sides and along the roof of the tower.

To solve this problem, several variants of "vortex generators" were proposed, of which only two were eventually accepted. The first is an apron in the frontal part of the hull, which breaks up a slender dust stream that runs on the forehead of the tank and passes under its bottom. Dust, having met with an apron, diverges in three directions: on both sides and towards the tower. The apron also serves as a damper for dust plumes when driving over bumps and potholes.

The second option is "burdocks" installed on dynamic protection units. They give the tower a more streamlined shape to smooth out the resulting vortices and direct them along the roof and sides, preventing them from flowing into the air intake pipe towering above the tower. In addition, the burdocks cut off and do not allow dust flows passing along the roof of the tank hull to rise up. Complementing these methods are side screens that hold whole dust clouds emanating from moving rollers and caterpillars under them.

All these rubber sheets work most effectively only on the march, when the tank passes and leaves behind a dust cloud.

As already mentioned, the effectiveness of these rubber elements depends on the speed of the tank and external conditions such as wind direction and speed. However, even in conditions of low tank speed or lack of wind, aprons and mugs can reduce the dust content of the roof of the engine compartment by 10-20%.

It is also worth considering that rubber elements can be damaged when driving through bushes, stones or other obstacles. Therefore, they are regularly checked and replaced if necessary.

In addition, it should be noted that the use of aprons and burdocks may adversely affect the appearance of the tank and its overall dimensions, which may limit its maneuverability in urban areas or other limited spaces.

Nevertheless, in general, rubber dust protection elements are an effective means of reducing the dust content of tanks, which increases their combat effectiveness and reduces the likelihood of breakdowns due to dust deposits.

Rubber shields on the forehead of the T-80 tank hull were used on earlier models, for example, on the T-80B, but only T-80U tanks and their modifications received a complete set. These machines have become a kind of world champions in the number of "anti-dust" measures, which made it possible to increase the resource of turbines in desert conditions to at least 300 hours. This proved to be very useful for fighting in the southern regions.