1961 Soviet medium tank
The T-62 is a Soviet main battle tank that was first introduced in 1961. As a further development of the T-55 series, the T-62 retained many similar design elements of its predecessor including low profile and thick turret armour.
In contrast with previous tanks, which were armed with rifled tank guns, the T-62 was the first production tank armed with a smoothbore tank gun which could fire APFSDS rounds at higher velocities (the U.S. prototype T95 medium tank was the first tank ever built with a smoothbore gun).
While the T-62 became the standard tank in the Soviet arsenal, it did not fully replace the T-55 in export markets due to its higher manufacturing costs and maintenance requirements compared to its predecessor. 
Although it was followed by later models in successor states of the Soviet Union, the T-62 remains in reserve in some countries formerly part of the USSR and in frontline use by other countries. Design features of the T-62 became standardized in subsequent Soviet and Russian mass-produced tanks.
Development history.
The initial requirements.
By the late 1950s, Soviet commanders realised that the T-55's 100 mm gun could not penetrate the frontal armour of newer Western tanks, such as the Centurion and M48 Patton, with standard armour-piercing shells. While 100 mm high-explosive anti-tank (HEAT) ammunition could have done the job, they were much less accurate than APDS shells, and the relatively low flight velocity resulted in poorer accuracy if used on moving targets. It was decided to up-gun the T-55 with a 115 mm smoothbore gun, able to fire kinetic energy penetrator armour-piercing fin-stabilized discarding sabot (APFSDS) rounds.
Trials showed that the T-55 was inherently unsuited to mount the larger weapon and work began on a new tank. The bigger gun required a bigger turret and turret ring to absorb the higher recoil. This in turn necessitated a larger hull, as the T-55 hull was simply too small to accept the new turret. The T-62 thus took shape, marking an evolutionary improvement on the T-55.
Obiekt 140.
After the delivery of the T-54 design, its lead designer Alexander Morozov turned his attention to a new design, the Obiekt 430. Obiekt 430 had a hull of welded rolled steel plates and a turret of cast and forged steel. The turret had three-layer armour with an overall thickness of 185 mm to 240 mm. It was armed with the new 100 mm D-54TS tank gun.
During this period, simpler upgrades to the existing T-54 design were assigned to a young engineer, Leonid N. Kartsev, the head of the OKB-520 design bureau of Uralvagonzavod factory (UVZ) in Nizhny Tagil. He had already led the development of the relatively minor upgrades to the T-54 that produced the T-54A (Obiekt 137G) and T-54B (Obiekt 137G2).
Kartsev and his design team started working on a new tank, called Obiekt 140 (this was also informally called the T-54M). The new tank had a torsion bar suspension with six road wheels made of aluminium. The turret was cast and armed with the same D-54TS tank gun and included the Molniya two-plane stabilization system. The tank carried 50 rounds and was powered by a V-36 diesel engine developed by engineer Artiemejev. The engine was placed on the bottom of the hull, a solution that reduced the height of the engine compartment. The Obiekt 140 weighed 37.6 tonnes.
In 1957, Uralvagonzavod built two Obiekt 140 prototypes which were put on trials soon after. The Obiekt 140 would be more expensive in serial production. Forced to abandon the Obiekt 140, Kartsev started working on yet another T-54 modernisation called the Obiekt 155. This design was more similar to the original T-54, but incorporated one useful feature from the Obiekt 140; the upper fuel tanks were fitted with mounts for tank gun ammunition. This increased the ammunition load carried by the tank to 45 rounds.
T-62A (Object 165).
At the end of 1958, Kartsev decided to modernise the Ob'yekt 140 turret. He fitted it with a cartridge-case ejector and mounted it onto a stretched T-55 chassis. He also considered that designs based on already produced vehicles had a higher chance of acceptance. The Ob'yekt 140 turret diameter, bigger than the T-55 turret by 249 mm, made redesigning the central part of the hull necessary.
Kartsev changed the arrangement of the torsion beams, which was necessary to keep the tank's weight balanced. The tank received the designation "Ob'yekt 165" and in November 1958 three prototypes were built. In January 1962, the Ob'yekt 165 was accepted for service under the name T-62A. In the same year, Factory #183 produced five tanks that were put into experimental service.
Object 166.
While working on a new tank, Kartsev was looking for a more powerful tank gun. The 100 mm D-10T and D-54 tank guns had a fierce opponent in the form of the British L7A1 tank gun. The Soviets decided to "recaliber" the already existing 100 mm D-54TS tank gun. The modifications made to the gun included removing the rifling of the gun, reducing the profile of the bullet chamber, removing the muzzle brake, lengthening the gun tube, adding an automatic cartridge-case ejector, and adding a bore evacuator in the middle of the gun tube (as opposed to the D-54TS tank gun, which had a bore evacuator at the muzzle).
The new 115 mm tank gun was designated U-5TS "Molot" Rapira. It was the first smoothbore tank gun to go into serial production where it received the designation 2A20. It was put in trials against the D-10TS tank gun, which armed the T-54B as well as some T-55 and T-55A medium tanks. These trials showed that the under-calibre projectiles fired from the U-5TS had a nearly 200 m/sec higher muzzle velocity. It became apparent that the maximum range of the new tank gun was almost double that of the D-10TS. The only serious drawback of the U-5TS tank gun was the fact that it was not as accurate as the D-10TS, because of the lack of rifling. However, the greater range of the gun and its extremely high muzzle velocity made the poor accuracy less of an issue.
The new U-5TS smoothbore tank gun was fitted into the Ob'yekt 140 turret at the end of 1960. The new tank received the designation "Ob'yekt 166". In 1960, both Ob'yekt 165 and Ob'yekt 166 prototypes passed their trials. Uralvagonzavod was preparing to start serial production of the new tank, though the General Armoured Directorate (GBTU) was paying much more attention to Morozov's Ob'yekt 430, which was in development since early 1952.
Morozov was supported by General Dmitry Ustinov, who was in charge of the Soviet military industry at the time. He did not see it as necessary to produce the new tank from Uralvagonzavod, but soon the situation changed dramatically with the appearance of a new American main battle tank, the M60. In 1961, Soviet military intelligence discovered that Britain was working on a new main battle tank armed with a 120 mm tank gun. Because of this, Marshal Vasily Chuikov, Commander-in-Chief of the Soviet Army's Ground Forces, demanded an explanation of the "Kartsev's tanks" case.
At a conference of GBTU and the Soviet ground forces committee, it became apparent that Morozov's Ob'yekt 430 tank was only 10% better than the serial T-55. Because of this, Morozov's project was deemed a complete failure. Though the representatives of Kharkiv Morozov Machine Building Design Bureau disclosed their work on the improved Ob'yekt 432 (which would ultimately become the T-64), Chuikov demanded that production of the Ob'yekt 166 medium tank be started immediately.
The OKB-520 design bureau of Uralvagonzavod provided another design, the Ob'yekt 167, which was the Ob'yekt 166 with a new more powerful V-26 engine using a charger, developing 700 hp (522 kW). Two prototypes were built in the middle of 1961 and passed the trials. This time the GBTU decided not to wait for the new medium tank to pass trials, and sent the Ob'yekt 166 into mass production in July 1961. The Ob'yekt 165 also entered service in very small numbers, under the designation T-62A.
Design.
The T-62 has a typical tank layout: driver's compartment at the front, fighting compartment in the centre and engine compartment in the rear. The four-man crew consists of the commander, driver, gunner and loader. Although the T-62 is very similar to the T-55 and makes use of many of the same parts, there are some differences. These include the hull, which is a few centimetres longer and wider, the different road wheels, and differences in characteristic uneven gaps between road wheels. Unlike the T-54 and T-55 medium tanks, the gaps between the last three pairs of road wheels are larger than the rest.
Armament.
The armament consists of the 115 mm U-5TS "Molot" (2A20) Rapira smoothbore tank gun with a two-axis "Meteor" stabiliser and 7.62 mm PKT coaxial general-purpose machine gun mounted on the right of the main gun. The 12.7 mm DShK 1938/46 antiaircraft heavy machine gun is mounted on the loader's hatch. It was optional until 1972 when all newly built tanks were fitted with the AA heavy machine gun.
The tank carries 40 rounds for the main gun. 4 rounds are placed in the turret, and the rest are stored in the back of the fighting compartment and in the front of the hull, to the right of the driver. It carries 2,500 rounds for the coaxial machine gun. All of the vehicle's armament is mounted in or on the round cast egg-shaped turret from the Ob'yekt 140 prototype main battle tank, mounted over the third pair of road wheels.
The T-62 was armed with the world's first smoothbore tank gun, giving it considerably greater muzzle velocity than the Western 90 mm and 105 mm tank guns of its time. It can fire BM-3 APFSDS-T, BK-4, BK-4M HEAT and OF-18 Frag-HE rounds. The 115 mm gun introduced the first successful APFSDS ammunition, albeit with a steel penetrator. A smoothbore gun allowed a significantly better performance (from 10% to 20%) over HEAT ammunition, which was considered the main ammunition type for fighting enemy armour at medium and long ranges.
The gun can be elevated or depressed between −6° and +16°. It is reloaded manually and gets automatically reset to +3.5° of elevation after it is fired if the stabiliser is enabled. Empty cartridges are automatically ejected outside the vehicle through a small hatch in the rear of the turret. The gun has a range of effective fire of about 4 km during day conditions and 800 m at night (with the use of night vision equipment). This tank was fitted with a Meteor two-axis stabiliser, which allows the T-62 to aim and fire while moving. Tests of the Meteor conducted by the US army gave the T-62 a first hit probability of 70% for a moving target at 1000 meters with the tank moving up to 20 km/per hour. This gave the tank a good advantage in dynamic battlefields and breakthrough operations, especially in Central Europe where most of tank battles would take place under the 1500 meters range.
Mobility.
The T-62 uses torsion bar suspension. It has five pairs of rubber-tired road wheels, a drive sprocket at the rear and an idler at the front on each side, with no return rollers. The first and last road wheels each have a hydraulic shock absorber. The tank is powered by the V-55 12-cylinder 4-stroke one-chamber 38.88-litre water-cooled diesel engine developing 581 hp (433 kW) at 2,000 rpm. This is the same engine as the one used in the T-55.
Because the T-62 weighs more than the T-55, it is less manoeuvrable. Like the T-55, the T-62 has three external diesel fuel tanks on the right fender and a single auxiliary oil tank on the left fender. The tank carries 960 litres of fuel in its internal and external fuel tanks. Two optional 200-litre drum-type fuel tanks can be fitted on the rear of the vehicle for an increased operational range.
Armour.
The T-62 has 5% thicker armour on the front of the hull (102 mm at 60°) and 15% thicker armour on the front of the turret (242 mm) than the T-54/T-55. The turret armour is 153 mm thick on the sides, 97 mm thick on the rear and 40 mm thick on the roof. The hull armour is 79 mm thick on the upper sides, 46 mm thick at 0° on the rear and 20 mm thick on the bottom. Although the armour on the front of the hull is thicker than in the T-55, the lower side armour (15 mm) and the roof armour (31 mm) are actually thinner.
Equipment.
One of