IS-7

## Design

The Armor was modulated to survive the 128 mm gun carried by the German Maus and Jagdtiger. The Hull front was made into the characteristic pike shape of the IS-3, and had around 150 mm of armor as well as effective sloping. The Lower glacis was weaker, at around 120 mm. The Turret was the strongest part, reaching 300 mm LOS (Line of Sight).

The side armor was very complex. The sheet that appears to be the side was only a thin plate. Behind it was the actual side armor, which was curved inwards.

The Turret was extremely curved and low, with thickly armored cheeks. The commander sat to the right, and the gunner to the left, with the two loaders at the rear. Some sources state that the mantlet reached 350 mm.

IS-7's armament was the 130 mm S-70 gun, which was 54 calibers long. An auto-loader with a crank was provided. This would drop the shell and propellant onto a conveyor, which had to be cranked to the rear of the breech. The ammunition would be rammed, and then the device would lift clear of the gun's recoil. The device was easy to use, and gave the tank a rate of fire of around 6 shells a minute. Sadly, the gun had to be returned to a neutral position after every shot for the loader to work, which made the acquisition of moving targets difficult.

The IS-7 was powered by the 1050 hp M50-T diesel engine. It was derived from a marine engine, and could propel the vehicle at 33 mph tops. It powered the sprockets through an 8-speed planetary gearbox.

The vehicle's weight was carried on 7 steel-rimmed road wheels per side on independent torsion bar suspension. The track was metal with retaining clips on the track pins.

## Machine Gun Craze

The IS-7 carried no less than eight machine guns, many positioned in a very comical way. Two were on the turret rear, facing backwards, and two were on the hull sides, facing forwards. A coaxial KPVT was placed above the gun, and another such weapon was mounted on the turret roof. It is still unknown how the crew were meant to aim the rear facing machine guns, as well as the front facing ones. For the later, the driver would have to turn the whole vehicle to aim, and for the rear facing ones, the turret would have to be turned. Furthermore, there was no elevation mechanism, meaning IS-7 would have to be on flat ground for the system to work. One can only assume how impractical these machine guns would be in combat. It is likely that a production model of the tank would remove these worthless weapons. A further two machine guns were mounted beside the main gun.

## **Action**

After initial trails, the vehicles were given to the state. Test drivers made it known that the vehicle functioned very well to steering instructions. During tests, one vehicle caught fire and was abandoned. The IS-7 was completely destroyed. This incident most likely stemmed from plastic linings on the fuel containers.

IS-7 was never accepted into production, and remained experimental. It is unknown why it was rejected, even though guesses can be made. The IS-7 was not a flexible vehicle, and would have served only in the breakthrough role. Other heavy tanks, such as the T-10, would have been more versatile. Only a single IS-7 remains today in the Kubinka Tank Museum.