In the previous column of "Schoolyard", a reader with ID of "Sanren in Xinqiao" raised a controversial question: the next generation main battle tank of France and Germany will use 130mm main gun, while the T-14 tank of Russia is currently equipped with a new 125mm gun, and there is a plan to replace 152mm gun in the future.So which is more suitable for the fourth generation main battle tank in the future, maintaining the current 125mm caliber, upgrading to the 130-140mm medium caliber, and upgrading to the larger 152-155mm caliber?
Previously, we often emphasized the fact that in most cases, tanks need to face various bunkers and fortifications rather than the other side's tanks.Therefore, most of the time, the number of multi-purpose ammunition such as grenades and armour piercing shells loaded in tanks is the largest.However, howitzer and armor piercing projectile have less requirements for artillery caliber, and the practice of increasing artillery caliber to enhance the power of howitzer and armor piercing projectile has marginal effects.In addition, increasing the caliber of the gun means that the number of ammunition loaded is reduced.Therefore, it is more harmful than beneficial to continue to increase the caliber of artillery on the current basis for the attack capability of tanks.
On the other hand, the tail stabilized armor piercing shell has been the absolute mainstay of tanks when facing enemy tanks since its inception.The armor piercing principle of this shell is to use the kinetic energy of the cartridge core to forcibly penetrate the armor of the other side.In general, the greater the kinetic energy of the armour piercing projectile, the stronger the penetration force. At the same time, the larger the caliber of the gun, the greater the kinetic energy of the projectile fired.In addition, anti tank operations often do not need to carry too many armour piercing projectiles, so increasing the caliber is definitely more beneficial than detrimental to improving the anti tank capability of tanks.
Having said all the effects of increasing the caliber of artillery on tank firepower, let's now talk about whether the tank needs to increase the caliber of artillery.Take the most classic high protection third-generation tank Leopard 2 (the refitted model after A5) as an example, its turret protection kit and body protection kit are derived from Leopard 2 Imp in 1995.The turret and car body have kinetic energy projectile defense capabilities of 800 mm and 700 mm respectively.Others, such as the latest T-14 in Russia and the 99A in China, are more advanced than the leopard 2A7 in the protection system, and their protection performance is at least as good as the leopard 2A7.
In sharp contrast to the protective performance of tanks, the development of armour piercing projectiles is weak.At present, in addition to the Russian "Vacuum-1" mentioned below, the most powerful armour piercing projectile in active service is the M829A4 of the United States.According to the muzzle muzzle velocity and the piercing rod structure, the armour piercing capacity of M829A4 should be slightly greater than 700 mm.Based on the above, even if it is stronger than M829A4, the threat to active heavy armored tanks is still insufficient.The performances of DM63, Lead 1/2, Phase III ammunition and K279 are worse.The upgrade of the fourth generation tank's overall architecture in the future will also enhance its protective capabilities, and the problem of armor being stronger than bullets will become more serious.Therefore, it is really necessary for active tanks to enhance their anti tank firepower.
In terms of improving the firepower of tanks, Rheinmetal's Rh-130 L/51 smooth bore gun and Russia's 2A82 smooth bore gun are two very mature programs.But about the 2A82 main gun equipped by the Russian T-14 tank, there is a lot of hard to tell the truth on the Internet.As we all know, besides playing tricks and drinking vodka, the biggest hobby of Russians is bragging.Therefore, Russian media and netizens have also produced a large number of "satellites", such as the 2A82 launch vacuum - 1 depleted uranium armor piercing projectile, with armor piercing power up to 1000mm.Others who are happy with black Russian equipment think that the 2A82 is nothing more than the 2A46 leather jacket, and its armor piercing power will not be higher.These various arguments will inevitably interfere with us to some extent, but we want to discuss the development trend of tank guns in the future. It is absolutely impossible not to thoroughly study this 125 mm smoothbore gun, the most powerful gun in the world at present.
Audiences familiar with the history of tank development in China basically know that the chamber volume of Soviet 125mm tank gun is about 13.4 liters, which is much larger than 9.8 liters of Rh 120.However, even if the potential of the two is tapped to the limit (lead - 1/2, M829A4), the armor piercing ability is only about the same, and even 125 shots are often less than 120 shots.This is mainly because the Western 120 gun is a full loaded shell, and the Eastern 125 gun is a sub loaded shell. The sub loaded ammunition limits the length of the barrel of the gun.The length and weight of the armour piercing projectile are limited, so the kinetic energy can only be increased by increasing the initial speed.However, when the muzzle velocity of the shell exceeds 1900m/s, its external trajectory will become very unstable (that is, it is impossible to hit), and it is not feasible.In other words, after the introduction of leading-1/2 and phase III shells, the problem with the Chinese and Russian tank guns was not that the propellant had poor power, but that the overall design of the vehicle did not allow the shells to have higher kinetic energy.Therefore, the firepower of Russian T-72/80/90 series tanks and China's 99/96 series tanks is close to the limit, which is not suitable for future operations.The Russian T-14 tank solved this problem.
At present, there is very little accurate information about the vacuum - 1/2 armor piercing projectile for T-14 tanks. However, according to the three lobe sabot of the vacuum - 1 armor piercing projectile with a length of about 700 mm, it is speculated that the flying body length of the vacuum - 1/2 armor piercing projectile is roughly the same as that of the M829A3/4 in the United States, and the weight of the projectile can also be very close to 10kg.In terms of muzzle velocity, it is believed that the muzzle velocity of vacuum - 1/2 is 1750m/s, similar to that of high-speed tungsten projectiles such as DM63.Based on this, we can roughly calculate that the exit kinetic energy of the vacuum - 1/2 projectile launched by 2A82 is about 15.3MJ, which is higher than any active armor piercing projectile (DM63 is about 13.7MJ, and lead - 1 and M829A3/4 are about 12MJ).
The structure of the T-14 tank "hatchback" contributes a lot to its strong performance.Unlike the Soviet style "hatchback" tanks in the past, the crew compartment and combat compartment of T-14 are completely separated, and the disk ammunition rack of the autoloader does not need to make room for the members on the turret, so the ammunition originally lying down can be placed vertically, and the ammunition loading method has changed from horizontal pushing to oblique pushing.This can make full use of the car body space and increase the length and weight of shells.The ammunition becomes longer and heavier, which makes it possible to further improve the propellant power.
But the solution of T-14 is still sewing and mending for three years.At present, the length of the bullet section of Vacuum-1 is just over 900mm, just catching up with the western 120mm full loaded projectile. Even the length of the 152mm 2A83 is similar to that of the 2A82 (this is determined by the overall layout of the tank), and even compared with the smaller diameter Rh-130, there is still a big gap.Therefore, if we want to make tank guns that can compete with western tanks in the future, we should first completely abandon the Soviet style design of ammunition distribution.
Of course, the penetration length of the armour piercing projectile cannot be extended indefinitely.From the current situation, it is difficult to continue to increase the length diameter ratio (in principle, the larger the better) of armour piercing projectiles.Although the United States has been developing pits with a length diameter ratio of 40, there has been no successful news so far.Therefore, in addition to the vacuum - 1 whose actual length is unknown, the longest flying body of the active armour piercing projectile is the M829A4 of the United States, which is 930mm long.The physical length of the armor piercing body is about 837 mm after removing the useless components such as the hood, tail wing and light tube.However, the 837mm depleted uranium threading rod is only about 685mm, and the rest is made of steel (it is speculated that the vacuum - 1 may also be a similar structure).In other words, with the current technical means, the limit length of the commonly used 22~26mm diameter bullet core of 120/125mm is just like this.If you want to increase the length of the piercing rod (which is one of the factors that determine the penetration depth), you must increase the diameter of the piercing rod at the same time, while increasing the length and diameter of the piercing rod will cause the projectile to become heavier and larger.If the projectile is too heavy, it will require stronger and more propellant to launch, and if it is too large, it will reduce the charge of the projectile (because the cartridge is always so large), which is also a vicious circle.
Now, Western tanks are also facing such a problem. Therefore, Rheinmetal chose to develop Rh-130 on the basis of Rh-120 this time, which is essentially to increase the chamber volume of the gun so as to improve the kinetic energy of the shell.According to the official statement of Rhine Metal Company, the kinetic energy of the Rh-130 projectile has increased by 50% compared with the previous Rh-120 L/55.Based on the above 13.7MJ DM53 standard discharge kinetic energy, the new shell of Rh-130 can reach an unprecedented 20.55MJ, which is 15.3MJ far away from the Russian vacuum - 1.
At this point, some people may say that the key to improving the power of tank guns is to increase the chamber volume rather than the caliber.In principle, this is true, but there will still be some other problems affecting the caliber of the gun, which is the bore pressure.Because the pressure of the gas is inversely proportional to its volume, the effect of reducing the bore pressure of the larger caliber gun barrel will be more obvious as the shells gradually move outward.In other words, the chemical energy of propellant can be used more effectively.For example, the peak chamber pressure of Rhine Metal's Rh-120 gun and Rh-105 gun (actually L7) when launching armor piercing projectiles is 630MPa and 430MPa respectively, but the pressure drop curve is steeper. The chamber pressure of the two guns at 4.8m of the projectile travel has been basically the same, which is due to the faster burning speed of the projectile propellant of 120 gun and the larger caliber of 120 gun.
If the caliber of the gun is limited and the propellant force/charge is increased, the utilization efficiency of the projectile to the propellant will be reduced. To improve the utilization efficiency of the propellant, the length of the barrel must be lengthened.The same is DM53/63. The initial velocity of launch on L/44 gun is only 1670m/s, and the kinetic energy is 12.4MJ; on L/55 gun, it can reach 1755m/s, and the kinetic energy is 13.7MJ. The kinetic energy difference is 10%.However, the gun barrel obviously cannot be extended indefinitely, because this will significantly increase the difficulty of casting the gun and the difficulty of designing the whole vehicle.So after much consideration, the only realistic option is to increase the caliber of the artillery.
Not only that, increasing the caliber is also conducive to tapping the potential of artillery in depth.At present, the barrel length of Rh-130 L/51 is only 3 cm longer than that of Rh-120 L/55. Even if there is a need to further enhance the firepower in the future, Rh-130 can "survive" by modifying shells, using more advanced propellants, and further lengthening the diameter of artillery, just like the previous Rh-120.In contrast, the T-14 2A82-1M gun has a diameter of 56 times and a barrel length of 7 meters, making it difficult to further tap its potential.This is probably the reason why the Russians proposed to replace the T-14 with a 152mm 2A83 tank gun.Therefore, considering the protection revolution of the fourth generation tank in the future, it is a wise choice to continue to increase the caliber of tank guns.
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