History of the Object 279
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The Object 279 heavy tank was a combat vehicle intended to break through prepared defences of the enemy in difficult terrains such as swamps, deep snow, and vertical obstacles like boulders, hedgehogs, etc. Such cross-country capability was achieved through four tracks. It was developed between 1954 and 1960 jointly by and in Leningrad under the leadership of . The presentation of the prototype for factory tests, as well as the hull and turret for firing tests, was planned for the last quarter of 1957, and the production of two machines by the second quarter of 1958.
By March 1956, the preliminary design was prepared and the technical project by December of the same year, having a 1:1 size wooden mockup by the 30th of December. In the summer of 1957, two sets of hulls and turrets were manufactured, and their armour was tested by shelling at the polygon. The technical project was finalized by November-December of 1957, having further increased armour protection. The deadlines for the new experimental vehicles were adjusted due to the large backlog of components needed, ending up in the last quarter of 1959 for the factory tests sample and the second quarter of 1960 for the last two samples. The factory prototype passed the factory tests and drove for 502 km (with the engine running for 86 hours). The second prototype was completed but the third prototype did not finish assembly.
At the direction of alongside the government, the project was terminated in January 1961 with the first and third prototypes being sent to the NIIBT landfill, and the second prototype left in storage at VNII-100.
The prototype of the tank had the classic layout scheme with a crew of four. To reduce the height of the hull, a diesel engine with a horizontal arrangement of cylinders was used and the driver was located in the recess between the tracks.
- Driver's Compartment
The driver's compartment featured the driver's seat, a control panel, mechanisms for driving the vehicle, two compressed air cylinders to start the engine, carbon dioxide cylinders for the fire protection system, and water pumps. Three TNPU-185A1 viewing devices were installed above the driver's seat on the roof of the hull where the entrance hatch is located. At the bottom of the hull, there was an emergency escape hatch behind the driver's seat. For driving at night, TVN-2T "Urol" night viewing devices were mounted instead of the TNPU-185A1.
- Fighting Compartment
The fighting compartment of the tank occupied the middle of the hull and turret. It housed the main gun and coaxial weapons, automatic stabilization, and guidance system "Groza-I", rangefinder sights, "Luna-II" night vision sight, radio station, tank intercom, gunner and commander seats to the left of the gun, one behind the other, and loader seat to the right of the gun. In the aft part of the compartment, there was an autoloader for 13 shots. For the convenience of the crew, a rotating floor was installed with a diameter of 1.83 m.
To keep the fighting compartment clean from any fumes and powder gases during firing, a supercharger fan of the filter system was installed in the turret, creating a positive pressure of 98-147 Pa. While the engine was not running and the gate valve was open, gases were removed through the air intakes; if the engine was running, they first entered the air purifier, into the engine, and ejected alongside the exhaust gases. The compartment was heated at low ambient temperatures by purifying heated air discharged from the engine supercharger through special pipes, which had shut-off valves that provided temperature regulation by adjusting the amount of heated air that was supplied.
On the roof of the turret above the commander's station, there was a cupola with five TNPA viewing devices and a central TPKU, with vertical viewing angles of -5 to +17 degrees, which could be replaced with a night vision TKN-1T "Uzor" device. The commander's cupola design was borrowed from the Object 278 heavy experimental tank. To illuminate terrain and targets, an OU-3 infrared illuminator was used. To clean the TPKU sight, a mechanical cleaner "Dvorink" was provided. Lastly, the commander could take over the turret rotation horizontally only, there was no vertical targeting designation. The gunner had a TNPU-185A1 device installed in the roof of the turret, allowing him a forward and left view. For the convenience of using the viewing devices, the commander's seat had height and direction adjustment, the gunner's seat was mounted on the rotating floor and had height adjustment only while the loader's seat was mounted on the upper part of the turret. All seats had soft cushions and could be folded and reclined. To enter and exit the vehicle, the gunner and commander used the commander's cupola hatch, 618 mm in diameter, and the loader used his hatch, 530 mm in diameter.
- Engine and Transmission Compartment
The engine and transmission compartment was located in the rear part of the hull, separated from the fighting compartment with a seal. The engine was mounted along the middle of the chassis right behind the compartment, the ejectors, water, and oil radiators were installed on both sides of the engine, the oil tank was located on the front left, and the air purifiers and heating system were in front of the engine. The heater boiler and water pump were installed below the fighting compartment floor, with a removable sheet for ease of access to the pump. The fuel tanks were outside the hull itself and were located inside two beams in the undercarriage reducing the fire hazard of the tank and allowing for the ammunition to be placed in the hull.
The main weapon of the tank was a 130 mm M-65 rifled cannon equipped with a slit muzzle brake, an ejection device for purging the barrel after firing, and an autoloader. A 14.5 mm KPVT machine gun was paired with the cannon, which could be used to help with the targeting. The armament complex featured an electrohydraulic two-plane stabilizer "Groza-I", optical periscope binocular sight rangefinder TPDS-36A (the third prototype used a vertically stabilized TPD2S rangefinder), and the night scope TPN-1 "Luna-II", used alongside the L-2 infrared searchlight. The paired KPVT included 800 cartridges, of which 400 were in a belt, stacked in special boxes, and the rest were in boxes. To fire the machine gun, one of the 50-round belts was attached to a cartridge box, and spent cartridges were thrown out through a special pipe that passed through a hole in the turret, and the belts were collected in a belt collector located at the lower part of the machine gun. The vehicle also contained two 7.62 mm AK assault rifles with 600 rounds of ammunition, 20 F-1 hand grenades, and a flare gun with 20 signal cartridges.
The TPDS-36A had an x8 magnification (9 degrees field of view, the rangefinder had 2 degrees) which could measure the range to the target from 1,000 m to 4,000 m. The aiming of the weapons could be carried out by the gunner from the remote control of the sight-rangefinder or the manual mechanisms for lifting the gun and turning the turret. The vertical aiming angles ranged from -5 degrees to +17.5 degrees and were limited by elastic stops, meaning the dead zone in front of the tank was 22.8 m. The TPN-1 night sight featured a x5 magnification (4 degrees field of view) and was installed on the roof of the tower, with the eyepiece located 170 mm above the TPDS, which had a removable sliding door to protect the optics from sunlight exposure and sharp flashes. Cleaning said eyepiece from dust and dirt was carried out with compressed air with a nozzle attached above the head of the sight.
The "Groza-I" stabilizer provided gun aiming speeds between 0.005-4.5 degrees per second in the vertical plane and 0.005-18 degrees per second in the horizontal. Vertical guidance was carried out by two power cylinders and to the right of the gun, a power control cylinder which carried out the stabilizing of the gun was located. To the left of the gun, a braking power cylinder was installed to brake and lock the gun when moving it to extreme angles, and when loading and firing. On the body of the braking cylinder, a hydraulic pump and a gearbox were attached for manual guidance. Horizontal guidance could be carried out with both the "Groza-I" stabilizer and a manual hydraulic drive. Switching the horizontal guidance from manual to motor was carried out by the commander by switching a hydraulic lever, which was inconvenient during the vehicle's movement, manual rotation of the turret achieved a maximum of 4 degrees per second. As already noted previously, the commander could take over the horizontal rotation using his target designation control panel. A major disadvantage of the stabilizer was that it did not prevent blocking of the driver's hatch in automatic mode which could lead to the failure of opening said hatch.
- Loading Mechanism
The ammunition of the gun consisted of 40 two-piece shots with partially burning sleeves (normal loadout used 34 AP and 6 HE shots), of which 13 were in the autoloader. The autoloader consisted of a mechanized ammo stowage (conveyor belt that moved the shells and another conveyor for the cartridges, feeding them to the loading lift), a pneumatic lift and tray, and a dispenser. Each conveyor was an endless chain of 13 links, each link having a projectile/charge in special grips. All the links were unified which ensured the loading of shells into the conveyor in any combination of AP or HE shells. The rotation of the conveyor happened clockwise and in case of electromechanical failures, manual backup drives were used. To lift the sleeve and lower the tray during loading, pneumatic actuators were used powered by a common air system, which consisted of an air cylinder with a 5-litre capacity and a maximum pressure of 14.7 MPa, located in the back of the sleeve conveyor. The loading of the projectile and cartridge was carried out by the chain dispenser, located on the back of the turret behind the shell conveyor, made similarly to the D-25TA dispenser. The projectile was sent into the gun chamber first automatically and for the cartridge, the loader had to roll the supplied sleeve onto the tray and press the loading button on his control panel. The loading of the gun was carried out at an angle of +0.5 degrees. When the loading angle was reached, a light signal that allowed loading was turned on for the commander and loader. The loader could pick, to the commander's decision, the type of projectile and cartridge case using the control panel. After sending the sleeve, closing the breech, and returning the tray to the starting position, the gun was automatically removed from the stopper and moved to the position that matched the sight. The combat rate of fire when using the autoloader reached 6-7 rounds/min.
The Ob. 279 had the most reliable protection of all heavy tanks. The hull weighed over 32 tons, 53% of the vehicle's combat weight. The armour protection was made to ensure that a 90 mm cumulative projectile could not penetrate the front and side of the hull and turret, and a 122 mm armour-piercing projectile at 950 m/s could not penetrate the hull from ±45 degrees and turret at ±90 degrees from the front at any range.
The tank's hull was welded from large cast parts. The front had a rounded shape with a thickness of the upper frontal part ranging from 230 mm at 45 degrees from vertical to 66 mm at 83 degrees, with the maximum equivalent thickness of the armour plate being 310 mm. There was also a non-removable anti-cumulative "screen" made of steel sheets installed in the bow of the hull along the perimeter. The lower frontal part of the hull had variable thicknesses of 226 mm to 95 mm at 45 to 78 degrees respectively, side parts in the upper part varied from 239 mm to 220 mm at 45 and 15 degrees, and the lower part 185 mm to 55 mm at 45 to 75 degrees. Additionally, the sides also had folding anti-cumulative screens installed. The rear of the hull roof was removable and split into three parts, the middle sheet above the engine and the side shutters above the radiators. The average roof thickness was 20 mm angled at 5 degrees. The stern of the hull was welded from two different cast parts. The upper part had a thickness of 73 mm to 37 mm at 35 to 65 degrees and the lower part 62 mm to 36 mm at 23 to 55 degrees respectively.
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Отечественные Бронированные Машины 1945-1965 гг. - Часть 1 - Легкие, средние и тяжелые танки, М. В. Павлов, И. В. Павлов (ISBN 978-5-85905-623-1)