Transition tank - IS-1 (IS-85).
On February 24, 1943, the Chelyabinsk Kirov Plant of the Soviet Union was ordered to develop a new heavy tank. The tank will be built on"Stalin"(IS) is a good indication of the expectations of the Soviet military at that time. Due to the fact that the plant had been obsessed with the development of the KV-13 for a long time, the designers naturally decided that the development of the new tank would be based on the KV-13. Inspired by the successful experience of the KV-1 2 with a 76-mm gun and a 152-mm gun, respectively, a 13-mm gun was also introduced on the modified chassis of the KV-76Project No. 233 for the 2-mm tank gun and Project No. 234 for the installation of a large-caliber 122-mm U-11 howitzer.
The Kirov plant unofficially named them IS-1 and IS-2. During the test run in March and April 1943, the prototypes of these two tanks showed themselves well. These two tanks were not so much prototypes of the IS series as successors to the KV-13: a chassis with five load-bearing wheels, a strangely shaped cast turret, all very different from the later IS-1 or IS-2.
At the test stage, one was captured by the Soviet Red Army"Tiger"Tanks were sent to the Kubinka experimental site. The USSR conducted firing tests of its armor using various artillery pieces. The results showed that of the existing artillery of that time, the most promising breakdown"Tiger"The frontal armor was an 85-mm anti-aircraft gun of the 1939 model. It can penetrate at a distance of 1000 meters"Tiger"Frontal armor 100 mm thick.
Preparations for a prototype of the new IS heavy tank were thus launched. Two 85-mm tank guns were ready for testing on the chassis of the new car: to 76The 2-mm tank gun was based on the expanded S-31 85-mm tank gun and the D-85T tank gun, developed from the D-5S of the Su-5 self-propelled gun. These larger guns made it necessary to redesign the turret of the tank, and the length of the hull was extended by 420 mm. Considering that the original overly compact chassis was the source of many problems, the end result was the addition of a pair of load wheels between the second and third load wheels of Project No. 1, a design of six load wheels on each side that already had the shadow of the IS-2.
In June 1943, a new prototype (designated IS-85) was tested in Kubinka along with the KV-85, which had just been completed at the time. Of the two new prototypes (Project 237) that left the factory, one was equipped with an S-31 gun, while the other was equipped with a D-5T gun. The tests lasted almost three months and included long-travel driving tests, full-fledged maneuverability and fire tests. After a long period of work by the designers of Kubinka, the chassis of the new IS tank was finally perfected.
On September 4, 1943, the IS-85 completed its tests and began its official service.
The product of Kursk - IS-2
While the IS-1 was conducting its final tests, a thrilling tank battle broke out on the Soviet-German battlefield in the Battle of Kursk. Despite the final victory of the Soviet Red Army in this Armageddon, during the battle, the Soviets discovered a terrible monster - Germany"Ferdinand"self-propelled anti-tank gun. This utilization"Tiger"The prototype was converted into an anti-tank gun with a powerful 88 mm L71 gun, but also a 200 mm thick front armor. The various anti-tank guns of the Soviet Red Army at that time, including the 1-mm guns on the IS-34 and T-85 tanks under development, could not penetrate its 200-mm-thick front armor head-on. In August 1943, just after the Battle of Kursk ended, the Soviet military decided to equip IS tanks with more powerful guns.
In the Battle of Kursk, such an event happened: when Germany"Tiger"When the tanks stormed a howitzer position of the Red Army, the Soviets had to fire flat fire at the German tanks with 122 mm A-19 cannon howitzers. They were surprised to find that the power of this kind of artillery was so powerful that no matter what kind of bullet was fired, as long as the German tank was hit by a single shot, it would be a dead death. The successful experience of Kursk encouraged the Soviets. They were determined to install 122-mm guns"Stalin"Tank.
The designers soon created the D-19 122-mm tank gun based on the A-30 and M-2 122-mm howitzers. This gun is fundamentally different from the U-2 gun installed on the original IS-11 prototype (Project 234). It was powerful, but the recoil was also very great, so it was necessary to install a brake on the muzzle.
The prototype of the IS-2 (JS-122) heavy tank (Project 240) underwent a series of tests in the autumn of 1943. The prototype was equipped with a modification of the D-2 gun - the D-25T tank gun. Since the chassis of the IS-2 was basically unchanged from the IS-1, the tests were mainly carried out around its fire system. In a series of tests at the time, the 122-mm gun mounted on the IS-2 showed good performance, after being transported to Moscow against captured German troops"Leopard"Shooting tests of medium tanks (as the Soviets called them heavy tanks) showed that at a distance of 1500 meters, the IS-2 122-mm D-25T tank gun could penetrate"Leopard"of frontal armor. And in the right"Leopard"During the firing test on the side of the turret, the shell actually penetrated the turret. The armor-piercing core of the turret is pierced"Leopard"A few meters from the other side of the tank.
The IS-2 heavy tank combat weight was 46 tons. The crew consists of 4 people: the commander, the gunner, the driver and the loader. The basic performance data of the tank is: Commander 983 meters, width 307 meters, the total height of the car is 273 meters, the bottom of the car is 465 mm above the ground. Compared to the small T-34, it is a behemoth. The IS-2 uses a V-2 series diesel engine, designated the V-2JS type, with a maximum power of 520 hp (380 kW). The engine was slightly less powerful than the V-2K on the KV tank, but had a simpler structure and greater versatility with the T-34. The IS-2 has a maximum road speed of 37 km/h and an average off-road speed of 12-19 km/h. Although it has a fuel load of 523 liters, the fuel consumption is quite impressive. On the road march, the fuel consumption is 217 liters per 100 kilometers, and 249 liters in off-road conditions. The maximum road cover is 240 km and the maximum off-road cover is 210 km, but the actual distance is usually only about 150 km. The climbing performance of the IS-2 is 35 ° and the unprepared wading depth is 13 meters, over the vertical wall height 099 meters, the width of the trench is 248 meters.
In terms of firepower, the IS-2 is dominated by a D25T 122mm 43x caliber tank gun with a pitch angle of 3° +20° and a reserve of 28 rounds. Under normal circumstances, ammunition is equipped with 30 armor-piercing shells and 70 grenades. Armor-piercing bullets are divided into two types: ordinary steel-core armor-piercing bullets and tungsten-core shell-out armor-piercing bullets. At the end of World War II, only a few experienced Guards tank units were usually able to load a tank with a few rounds of tungsten core ammunition to face Germany at a distance of about 1 kilometer or more"Tiger King"The frontal attack of the tank. The 122-mm D-25T tank gun used tracer ordinary steel-core armor-piercing shells at a distance of about 1 km and had a vertical armor-piercing thickness of 160 mm. Auxiliary ** for two 762 mm DT on-board machine gun with 1000 rounds of ammunition, and some later production versions of the improved IS-2M were fitted with a 127-mm DSHK anti-aircraft machine gun with a load of 500 rounds.
The thickness of the armor of the tank was: 100 mm of armor under the front of the hull of welded structure, with an inclination angle of 30 °; The upper front armor of the hull was 120 mm, and the inclination was 60 °; hull side armor 80 mm, vertically placed; rear lower armor of the hull 60 mm with an inclination of 41 °; The upper side armor of the hull was 60 mm, and the inclination angle was 48 °; underbody armor 20 mm; Top armor of the hull 30 mm; The front armor of the cast turret 100 mm, plus the shield, had a total thickness of 140 160 mm; side and rear armor 90 mm with a smooth arc transition; turret roof armor 30 mm; Welded conning tower armor in the upper part of the turret 90 mm.
Simplicity is beauty Evaluation IS-2
Terrible production capacity.
In times of war, the most important resource in the cost of production of combat vehicles is manpower. In this regard, the economy of the IS-2 tank is particularly prominent. Comparing the production of tanks in the USSR and Nazi Germany, you will see an order of magnitude difference in the number of hours spent on the production of their respective tanks: the production of one"Tiger"It takes 250,000 man-hours to produce one"Leopard"150,000 man-hours are required, while it takes 50,000 man-hours to produce an IS-2. One is produced in Germany"Tiger"In the USSR, 5 cars were built"Stalin"!If you just fight for consumption with such a gap, even if"Tiger"with"Stalin"The battle loss ratio was 1:1 or even 1:2, and the Germans had no hope of winning at all.
Another reason why Soviet designers chose 122 mm as the caliber of tank guns was precisely to reduce the number of man-hours in production. Although the ammunition of the D-2 gun differs from that of the A-19 cannon howitzer, both guns can be produced using the same machine tools and operating processes, which reduces the investment in manpower and equipment. Looking back at the production of other army ** in the USSR, a similar situation was widespread.
According to the old Chinese proverb, the Germans' instinct for complex machines may be infamous for their ingenuity. And the Soviet Union's keen sense and ability to grasp the army ** impressed us. As soon as any new ** appeared on the battlefield, the Soviet Union quickly ate the essence of it, to paraphrase an advertising slogan"Absorption is particularly fast", and can be converted into combat power with the fastest speed and quantity.
This situation reminds us of the confrontation between Genghis Khan, armed with a simple and practical compound bow, with a Mongol cavalry with a single tactic, and Polish knights with elite armor and tall horses. The Mongol cavalry once swept half of Western Europe with a force of 30,000 men. In Western film and television works (such as "Soldiers Coming to the City"), the Soviet army in World War II is often scandalized with crowd tactics, but in fact, it seems that there is a greater element of fear.
Artillery trade-offs.
The IS-2's 122-mm gun was so powerful that until the end of World War II, commanders of Soviet heavy tank units did not need to care about what new tanks their opponents were equipped with. Because after that, none of the new German tanks were able to withstand the blows of 122-mm guns at common distances.
Split ammunition was used on the 122 mm tank gun only because its prototype - the 122 mm howitzer was also used in split ammunition. Although the split ammunition made the tank turret compact, it significantly reduced the rate of fire of the tank gun. At one time, there was only 1 15 shots. It was only after the addition of a second loader and the improvement of the turret arrangement that it barely reached the level of 2 rounds. This rate of fire, combined with a bomb load of 28 rounds, seriously limited the combat effectiveness of the JS-2. This was difficult to overcome under the conditions of the time, and increasing the bomb load inevitably increased the volume and weight of the hull, which greatly reduced the maneuverability of the JS-2. In the end, the Soviet military decided to ignore these problems for the time being, and let the JS-2 enter service first In order to obey the overall performance of the ** system, some individual performance indicators can be abandoned.
Compared to the Germans, this is a very different design idea. The Germans always pursue the perfection of the machinery and every subtle performance to meet the requirements, when the technical level temporarily does not meet the requirements, they do not hesitate to make the system complex to meet each performance index, and finally design out of the precision and complexity, and the reliability is insufficient. For example, the German medium tank"Leopard"The weight of the model is actually comparable to that of the Soviet heavy tank JS-2, and the difference between the two in terms of firepower and armor is clear at a glance. The reason is definitely not because of the problems with Germany's industrial design capabilities, but because of the different guiding ideologies.
o Chassis trade-offs.
The total combat weight of the IS-2 reached 46 tons, which was a test of its chassis. The chassis with torsion bar suspension did not have major problems in the test, but from the performance data obtained, it did not perform well, it can only be said"Not satisfactory"。
Due to the limitations of material technology and other design conditions at that time, the torque of the torsion bar suspension device was limited to a small range, and the strength of the torsion bar was not enough. Moreover, the IS-2 has only six pairs of load wheels and 12 stress points, each of which has to bear a weight of nearly 4 tons. Especially when the tank is moving on undulating terrain, the torsion bar attachment points are subject to greater impact. When maneuvering through various complex terrains and obstacles, the suspension of the IS-2 appeared very stiff and did not act as a good shock absorber. German"Tiger"、"Leopard"with"Tiger King"Tanks use staggered load wheels, wide tracks and a large number of load wheels, so that the weight of each moment point is reduced. As a result, German tanks generally had a better ride than Soviet tanks, and thus had a certain advantage in terms of sustained combat capability, which was of great significance to the German army, which valued elite troops.
The IS-2 tank still uses the V-2 family of diesel engines. For a heavy tank, it may be a little less powerful, but this allows for maximum versatility: almost all Soviet tanks were equipped with V-2 series engines and their modifications, which made them relatively easy to maintain.
In terms of armor protection, the USSR conducted rather harsh tests on the IS-2. As a heavy tank, the Soviet Union required the IS-2 tank to defend itself against the ZIS-3 Type 76 in a 360-degree direction and at a range of 500 600 metersStrike from 2 mm tank guns. The results of live firing showed that the thickness of the armor of the IS-2 was sufficient for the above requirements!
When the heavy tank IS-2 named after Stalin came off the production line, Stalin was quite satisfied with this powerful **. He said confidently"We are going to end the war with this tank! "
To be continued - IS series heavy tanks (below).
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