The Obiekt 279, or Object 279, (Объект 279) was a Soviet experimental heavy tank developed at the end of 1959. This special purpose tank was intended to fight on cross country terrain, inaccessible to conventional tanks, acting as a heavy breakthrough tank. It was planned as a tank of the Supreme Command Reserve. Design The tank was developed at the Kirov Plant in Leningrad by a group headed by the engineer L. Troyanov. The work on the tank started in 1957, which was based on a heavy tank operational requirements developed in 1956, and a pre-production tank was completed at the end of 1959. This unique tank boasted increased cross-country capability. It featured four-track running gear mounted on two longitudinal, rectangular hollow beams, which were also used as fuel tanks. The tank suspension was hydro-pneumatic with complex hydrotransformer and three-speed planetary gearbox. The track adjuster was worm-type. The specific ground pressure of this heavy vehicle did not exceed 0.6 kg/cm2 (~8.5psi). The track chain, running practically along the whole track length provided for increased cross-country capabilities on swampy terrain, soft soils and area full of cut trees, Czech hedgehogs, antitank obstacles and the like. The tank was equipped with the powerful 1000 hp 2DG-8M diesel engine, enabling the 60 metric ton tank to attain 55 km/h (34mph) speed, with active range of 300 km (186 miles) on one refuel. It also had auto fire-fighting systems, smoke laying equipment and a combat compartment heating and cooling system. Armour The tank hull, with a maximum armour thickness of , was covered by a thin, elliptical shield protecting it against APDS and shaped charge ammunition. It comprised large cast irregular shape structures of variable thickness and slope. The all-cast front part of the hull was rounded in shape with thin armour panels against HEAT projectiles, which ran around the edges of the front and sides of the hull. The sides of the hull were also cast and had similar protective armour panels. The all-cast turret, with a maximum armor thickness of 319 mm, was rounded and had anti-HEAT protective panels. The turret ring was also heavily protected. The tank was equipped with chemical, biological, radiological, and nuclear (CBRN) protection. Armament The tank was armed with the 130 mm M-65 rifled gun. The secondary armament was a 14.5 x 114 mm KPVT coaxial machine gun with 800 rounds. The weapons were stabilized in two