The IS-7

heavy tank A heavy tank is a tank classification produced from World War I to the end of the Cold War. These tanks generally sacrificed mobility and maneuverability for better armour protection and equal or greater firepower than tanks of lighter classes. ...

, also known by its project name Object 260, is a

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

tank that began development in 1945. The vehicle existed only in prototype form and was cancelled in favor of the

T-10 tank The T-10 (also known as Object 730 or IS-8) was a Soviet heavy tank of the Cold War, the final development of the IS tank series. During development, it was called Object 730. It was accepted into production in 1953 as the IS-8 (''Iosif Stal ...

Design and production

The IS-7 heavy tank design began in

Leningrad Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...

in 1945 by Nikolai Fedorovich Shashmurin Weighing 68

tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the s ...

s, thickly armoured and armed with a 130mm S-70 long-barrelled gun, it was the largest and heaviest member of the IS family and one of the most advanced heavy tank designs. IS-7

The armour was engineered in a similar fashion to the

IS-3 The IS-3 (also known as Object 703) is a Soviet heavy tank developed in late 1944. Its semi-hemispherical cast turret (resembling that of an upturned soup bowl) became the hallmark of post-war Soviet tanks. Its pike nose design would also be mir ...

, with a

pike nose A pike nose (from ) is a configuration of vehicle armour in which an armoured vehicle's frontal armour consists of three angular plates put together to form a cone-like shape, similar to the nose of a Pike (fish), pike, from which the name stems. ...

on the upper glacis sporting 150mm of armor sloped at 65°. This armor was designed to defeat rounds from the

Jagdtiger The ''Jagdtiger'' ("Hunting Tiger"; officially designated ''Panzerjäger Tiger Ausf. B'') is a German casemate-type heavy tank destroyer (''Jagdpanzer'') of World War II. It was built upon the slightly lengthened chassis of a Tiger II. Its ordn ...

's 12.8cm Pak 44 from as close as . The lower glacis was designed to be 100mm but a measure taken by

Nicholas Moran Nicholas Theodore Moran (born 1975) is an American author, amateur historian, video game consultant, YouTuber and US Army National Guard officer. Early life and education Moran's ancestry is Irish on his father's side and Greek on his mother's.

found it to be as thick as 110-120mm depending on welding variations. The armor on the sides was also 150mm on the upper side plate and 100mm on the lower side plate. Behind the lower side plate, inflatable bags could hold fuel. The turret mantlet was 350mm thick and the turret itself between 240-250mm angled at 50-60 degrees. When shot at frontally, the extreme angle that the pike nose presents results in a much higher likelihood of a ricochet. Thus, armour protection could be enhanced without having to use excessive amounts of materials. However, if the pike nose was shot from an angle other than straight on, the angle of impact would be less extreme and protection reduced. The tank's interior has a "V" shape seen from the front of the tank so that the side armor was spaced. In spite of its weight, it was easy to drive due to numerous hydraulic assists. The loaders noted that the IS-7 was comfortable and that the

autoloader An autoloader or auto-loader is a mechanical aid or replacement for the personnel that load ammunition into crew-served weapons without being an integrated part of the gun itself. The term is generally only applied to larger weapons, such as na ...

was easy to use. It was also able to achieve a top speed of 60 km/h, thanks to a 1050-horsepower diesel engine, giving it a

power-to-weight ratio Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement ...

of 15.4 hp/tonne, a ratio superior to most contemporary medium tanks. Its armour was not only immune to the

's 12.8 cm PaK 44 but was even proof to its own 130mm. Due to unknown reasons, most likely because of the considerable issues arising from its mass (bridges, rail transport - no Soviet/Russian tank accepted into service afterwards exceeded 55 tonnes), the tank never reached the production lines. The 130mm S-70 was a conversion of a naval gun, firing a ~

armor piercing Armour-piercing ammunition (AP) is a type of projectile designed to penetrate armour protection, most often including naval armour, body armour, and vehicle armour. The first, major application of armour-piercing projectiles was to defeat the t ...

round ~. The loading mechanism for the gun was an assisted loading mechanism with a conveyor belt system. It held six ready rounds that would then have to be refilled. The rounds came in two parts: shell and propellant (charge). The IS-7 had a massive number of machine guns (eight) and probably would have lost five of them if it had entered production, according to Nicholas Moran. Despite being an excellent break-through vehicle, the IS-7 was heavy, expensive and overspecialized; the T-10 being better suited for longer battles and protracted warfare alongside being easier and cheaper to transport. Work on the IS-7 ceased in 18 February 1949. The tracks were specially made for the IS-7, while those used in the IS series models were rather similar. The track was the first Soviet track to use rubber bushings with single pins, retained in place by bolts. The IS-7 has a total of seven road wheels attached to road wheel arms on torsion bars, limited by

volute spring A volute spring, also known as a conical spring, is a compression spring in the form of a cone (somewhat like the classical volute decorative architectural ornament). Under compression, the coils slide past each other, thus enabling the spring to ...

bump stops, and hydraulic shock absorbers. The rear allowed for external fuel tanks to be carried. The IS-7 is now being restored to running order by the Kubinka Tank Museum.

Variants

* Object 261 – Self-propelled gun variant of the IS-7 with a 152mm gun at the rear. Only a wooden mockup was produced. * Object 262 – Self-propelled gun variant with a 152mm gun at the front. * Object 263 – Tank destroyer variant of the IS-7. A 130mm S-70A gun is mounted in a rear, semi-enclosed fighting compartment.

References

{{Reflist

Surviving vehicles

Kubinka Tank Museum The Kubinka Tank Museum (Центральный музей бронетанкового вооружения и техники - Tsentral'nyy Muzey Bronetankovogo Vooruzheniya I Tekhniki -Central Museum of Armored Arms and Technology) is a larg ...

, Russia

External links

Part 1
an
Part 2
of "Inside the Chieftain's Hatch: IS-7" video reviews Heavy tanks of the Soviet Union

Design and production

Variants

See also

References

Surviving vehicles

External links