Object 906B – airborne tank for two people
There are no surviving images of the running prototype of Object 906B, but its predecessor, Object 906, is available “in metal”.
Explanatory note
The Volgograd Tractor Plant is famous for its combat equipment. The local design bureau created the entire line of airborne combat vehicles, and before that, the BTR-50 left the plant gates. VGTZ specializes in light amphibious vehicles. A special place is occupied by the PT-76, a replacement for which they began to look for in the early 60s - ten years after the launch of serial production. The machine had to surpass its predecessor in all respects - a larger gun caliber, thicker armor, a more powerful engine, and less weight. In addition to the ability to swim, танк had to be able to descend from the sky with parachutes. The result was a kind of forerunner of the BMD, only woven from extreme parameters.
Below is an explanatory note to the project of the experimental vehicle Object 906B, the development of which was approved in July 1962. The vehicle was developed on the basis of another experimental product, Object 906, and was significantly different from the original. For example, the number of crew members was reduced from 3 to 2 - a more than controversial decision. No less surprising is the refusal of water jets on the amphibious vehicle. Or the location of the air intake on the roof of the turret. It seems that the concept was built around one requirement - to build as compact a tank as possible. And it turned out to be successful, but no one needed it. In October 1962, a running model was created in metal, which remained in a single copy. The authors of the once top secret explanatory note are the chief designer of VGTZ I. V. Gavalov and the leading designer of the topic Yu. The text is given without abbreviations with the necessary transcripts.
Object 906B
Brief explanatory note to the project of a light floating airborne tank
Introduction
The main layout provisions determining the dimensions and location of the tank compartments were: using the displacement of the entire tank volume (hull and turret), and not just the hull, placing the driver's compartment in the turret, implementing an air intake system on the roof of the turret for isolated power supply for the crew, as well as the engine and cooling system.
The tank has a denser layout than Object 906, which reduces the height and length of the armored hull.
The forward part of the hull contains: fuel tanks, rack tanks for cannon shots, batteries, a bunker for collecting spent cartridges and, partially, a tank spare parts kit.
In the middle part of the hull, on one common rotating platform, there is a fighting compartment and a control compartment of the tank, an emergency hatch, electrical equipment for the battery charging system, fire-fighting equipment, an air-intake system, a tank gun spare parts kit and a personal crew kit.
The aft section contains the engine and transmission compartment (ETC) with the following installed: a power unit from the UTD-20 engine and GMT, a hydraulic control drive, a cassette-less air cleaner, a heater with an oil tank, and a cooling system for the engine and GMT.
The floating tank has a differentiated distribution of volumes to ensure the required displacement and buoyancy reserve. The total volume of the tank is 15,036 m3The total volume required to provide the tank's displacement is distributed as follows:
a) body -70%;
b) tower -25%;
c) chassis -5%.
Obtaining a new shape and area of armor projections makes it possible to significantly reduce the combat weight of the tank.
Chassis
The armored hull has a rectangular cross-section, 750 mm high, with vertical sides, made of grade 2P armor steel.
The bow of the hull is cut at an angle of 55° from the vertical, the stern has a variable slope.
The hull mudguards are made in the form of hollow boxes made of thin sheet material and filled with PS-B foam plastic (non-pressed).
The placement of the driver-mechanic in the turret and the installation of a small-sized power unit made it possible to reduce the height, as well as the length of the hull along the largest perimeter, where the plates have the greatest thickness (bow, side and stern), due to which the weight gain was the greatest.
The chosen shape is easy to manufacture and reduces the length of welds. A small number of cutouts for hatches provides a significant increase in rigidity.
The frontal projection of the hull ensures non-penetration from a distance of 150 m with a B-32 bullet of 14,5 mm caliber, and the side (entire) projection - from a distance of 150-200 m with a B-32 bullet of 7,62 mm caliber.
Object 906. Formally, Object 906B was developed on this basis.
Turret and weapons
The tower is a combination of two three-dimensional figures: the front (frontal) part is conical in shape, and the side part is trapezoidal.
The dimensions of the turret in the horizontal plane are significantly developed, occupying the entire width of the hull at the base.
The height characteristics of the tower are differentiated, and its height in certain areas is significantly reduced by means of the following main layout measures:
- by moving the gun trunnion axis forward and bringing the gun to the loading line at an elevation angle of +30, which made it possible to lower the rear part of the turret;
- use of a one-piece stamped roof with small openings for hatches;
- an increase in the diameter of the turret ring, which no longer limited the elevation angle and made it possible to accommodate the driver’s compartment, and the height of the turret in the frontal part was reduced;
- the gun is installed with its trunnions in sockets welded directly to the body of the turret hull, and has a minimal embrasure (320 x 300 mm) with no bulky frame.
The design of the turret is significantly simplified and is made of welded 2P steel armor plates with variable angles from the vertical along the perimeter.
The frontal projection of the turret resists a 32 mm B-14,5 bullet from a distance of 100 m, the side and rear projections are designed to resist penetration by a 32 mm B-7,62 bullet from all distances.
The D-58 tank gun, paired with the SGMT machine gun, is installed in the tank turret using trunnions in the corresponding sockets of the turret embrasure.
The embrasure of the bank is covered by a mask, the armor resistance of which is the same as the armor resistance of the frontal projection of the turret.
The mask has shock absorbers to limit vertical aiming angles and grooves with sealing devices that prevent lead splashes and water from penetrating inside. The mask is covered from the outside with a cover made of non-flammable, waterproof fabric.
To the left of the gun there is a combined non-illuminated sight of the TPNB-2 type.
The installation of a TPNB-2 type sight, in addition to ease of use, improves the combat qualities of the weapon:
- lack of illumination (bulky protruding illuminators with drives);
- compact arrangement of sighting devices;
- low weight;
- shock wave resistance.
To the left of the commander-gunner is a horizontal guidance rotating mechanism (PMB), equipped with an azimuth indicator and a split spring-loaded combat gear. The turret ring is made with a clear size of 2152 mm. Two air intake boxes with rotating diffuser louvers are attached to the roof of the turret.
The rear part of the turret has an opening for installing a retractable pontoon device with a drive and for mounting and dismounting the gun loading mechanism. The loading mechanism is designed for a capacity of 23 cannon shots of the D-58 cannon.
The bells of the annular air duct for the engine cooling and power supply system are welded to the roof and side walls of the tower.
The rotating turrets of the commander-gunner and driver-mechanic are fundamentally similar, being a hatch-manhole with a clear opening of 480 mm.
The turrets have prismatic observation devices, which are accepted as a single observation device for the tank. The turret has a rotating suspended platform with a diameter of 1900 mm, with the VKU-519 (rotating contact device) located in the center.
Department of Management
To the right of the tank gun is an independent mobile control compartment of the tank, which has two ball bearings in height: at the top is a turret with observation devices and a hatch, at the bottom is a ring with a VKU on the platform of the fighting compartment.
The control compartment contains: the driver's seat, control levers and pedals, central instrument panel, air-liquid cleaning system for viewing instruments, lower ball bearing with VKU-519, tools, etc.
To ensure the constant position of the driver and the observation devices of the turret, there is a cardan transmission device for kinematic connection with the turret ring.
Control drives are divided into three groups of mechanisms:
- asking;
- distribution;
- executive.
The control mechanisms are located in the driver's compartment and include:
- speed selector;
- steering levers;
- mountain brake and fuel pedals.
Distribution and actuator mechanisms are located in the MTO and on the transmission.
The kinematic transmission from the driving mechanism to the distribution mechanism during the movement of the driver-mechanic's compartment in a circle from the rotation of the turret or when parked is carried out by a transmission gear mechanism (PGM).
The PSM is a package of leading, idler and driven gears located on the ball bearings of the combat compartment platform. The leading and driven gears of the block have carriers: the former are connected to the setting control bodies, and the latter - to the distribution mechanism.
All tank controls act on the hydraulic system (except for the fuel supply and the exhaust brake) and therefore require minimal effort to use with automated control.
Engine-transmission compartment
In the aft part of the hull there is a power unit installation consisting of a UTD-20 engine from Plant No. 77 and a hydromechanical transmission.
This 1500 mm long block, mounted on three points with shock absorbers, ensures absolute rigidity of the unit, strict and constant alignment of the engine and gearbox, eliminating the influence of possible deformations of the bottom and the transmission of vibration to the body.
The engine and gas turbine cooling system is an ejector, closed type, located along the sides of the hull, and has a valve system on the outlet track (diffuser) for sealing while afloat.
When the engine is running while afloat, the exhaust gases are released using a two-way valve, bypassing the ejector, and are discharged directly into the water.
Between the engine bulkhead and the engine, under the roof of the housing, the following are installed:
- single-stage automatic air cleaner type VTIA, which does not require maintenance during operation;
- a dual-action heater, designed, firstly, to heat the power unit before starting and, secondly, when moving afloat, to cool the cooling system of the machine with sea water, with the ejectors turned off.
The final drive is planetary, coaxial with the load shaft of the hydromechanical transmission.
Fuel system
The fuel system consists of front fuel tanks with a capacity of 315 liters, rack tanks with a capacity of 300 liters and a fuel main system. All tanks have one supply tank with a capacity of 7 liters, enclosed in the body of the fuel gauge and valve, located in the MTO on the engine bulkhead. The distribution valve is connected to the fuel gauge, which shows the amount of fuel in the included group of tanks. The system is filled through the filler necks of the tanks, located in the bow of the hull.
The fuel supplied to the engine is preheated in the heating boiler.
Chassis
Rollers with a diameter of 670 mm with aluminum alloy disks, a total of 12 pieces, 6 rollers per side. The caterpillar is fine-link, silent-block with a total number of tracks of 192 per vehicle. The suspension is hydropneumatic, allowing the tank to be lowered, raised by 280 ÷ 250 mm and the suspension stiffness to be adjusted using a hydraulic control drive. The assembly of the suspension, support rollers and supporting rollers is block-type, requiring no adjustment work.
Electrical and fire-fighting equipment
The basic installation diagram of electrical and fire-fighting equipment is distinguished by the small length of wires, cables, the number of lighting and other devices, as well as the routes of the main pipelines of the UAPPO.
SPTA
The spare tool and accessories of the developed object are distinguished by a reduction in the nomenclature and quantity carried on the tank.
Air intake and ventilation system
The intake of atmospheric air for powering the engine, cooling system and ventilation of the tower is carried out according to a fundamentally new scheme.
Fresh air passes through two air intakes with rotating diffuser louvers located on the roof of the turret, directed into the annular air duct of the hull, and enters the MTO, which has a sealed engine bulkhead.
The turret ring and the annular air duct of the hull have fixed sealing devices controlled by a single pneumatic line of automation, excluding water ingress when moving afloat and used in PAZ (anti-nuclear protection) measures. The intake and injection of atmospheric air during PAZ for the tank crew is carried out by a separate fan with filters from BOV and HOV (biological and chemical poisonous substances), located in the aft part of the turret on the support ring of the ring. When moving afloat, air is taken from the air intake on the roof of the turret.
A large front for fresh air intake (2114 x 600 mm) into the MTO provides a positive solution to the issue of ventilation, blowing of the engine and other tank units.
When moving afloat in marine conditions, it is envisaged to install folding rubber-fabric pipes on the air intake openings simultaneously with the placement of masthead lights on these pipes.
Thus, the presence of 2 independent air ducts for the crew and MTO positively resolves the issue of protection from chemical and biological agents in all cases of tank operation.
GROOVE
Biological protection from penetrating radiation when operating in radioactively contaminated areas, ensuring the possibility of staying in a contaminated zone with a radiation level of 300 roentgen-hour, has been significantly redesigned due to the following design measures:
- placement of crew members in the tower in a small area;
- shielding the crew compartment with metal-intensive units, components, fuel and lubricants and ammunition;
- installation of a knife device for cutting off the contaminated top layer of soil across the entire width of the machine.
Complete protection of the crew from radioactive dust, chemical and bacteriological toxic substances is ensured by the presence of two air ducts for the MTO and the tower, isolated from each other, with the installation of highly efficient filters on the blower fan.
Thus, the above-mentioned measures make it possible for tank crew members to stay in radioactively contaminated areas with a weakening factor of at least 4 times.
Float
To move the tank on land and to overcome water and marshy obstacles, a single propulsion system is used - a caterpillar one.
The rejection of a special water-jet propulsion unit allowed to reduce the metal consumption of the transmission and control, simplify the tank design and eliminate the hull displacement losses. To ensure maximum speed afloat and increase the efficiency of the tracked propulsion unit, a number of basic design measures are envisaged:
- installation of hydrodynamic casings on the body;
- use of the deep track of object 906 with additional processing, providing an increase in traction force on water without increasing weight or worsening movement conditions on land;
- retracting the chassis with uniform tensioning of the track in order to eliminate loss of power due to rewinding;
- less resistance of the outer contour of the tank.
In order to test the performance of the 906B model, which has a displacement turret volume, the Volgograd Tractor Plant (VGTZ) Design Bureau conducted model tests in a gravity-type pool in March 1962 and obtained satisfactory performance results.
To regulate the trim and displacement afloat, a new design scheme is proposed using the space between the side walls of the turret and the main gun for a retractable pontoon device. The aft part of the pontoon is an additional armor protection of the turret from a B-32 bullet of 7,62 mm caliber from any distance. The retractable pontoon along the opening of the aft part of the turret has a fixed sealing device controlled by a single pneumatic line of automation. The pontoon device during the afloat can stabilize the change in the static trim of the tank from the consumption of fuel, ammunition, etc.
Visibility
The areas that are not visible to the tank crew members meet the generally accepted tactical and technical requirements. The driver's visibility is significantly improved both on land and afloat, due to the location of the observation devices in the cupola on the roof of the turret. Driving the tank from a rotating turret does not cause any particular difficulties for a driver with experience in driving armored vehicles, and does not require significant training time.
Conclusion
In the new light amphibious tank, it is possible to improve the tactical and technical characteristics without fundamental redesigns due to the following measures:
- install a launcher instead of the D-58 tank gun for
controlled and uncontrolled missiles for the purpose of weight loss and gain
tank firepower;
- improve the tactical qualities of the tank by installing a new one
high-speed, more powerful, multi-fuel engine ZTD design
Plant No. 75;
- the presence of a small-sized power unit of the cooling system, block units and assemblies makes it possible to use the idea of a unified chassis on the basis of the new tank for the production of a family of special airborne combat vehicles included in an armored unit, with the aim of increasing the autonomy of action in operational space.
These include:
- a high-speed, highly cross-country infantry fighting vehicle (IFV) for 10-12 people with active fire on the move by the entire landing force, equipped with a "Spear" type weapon;
- a high-speed, highly cross-country combat engineering vehicle (BIM) with the capacity to carry 2,5 tons of fuel (refueler), a winch, a crane, a self-burying knife device and other repair equipment;
- a high-speed, highly cross-country combat vehicle for transporting and launching tactical missile systems or a whole group of anti-tank missile launchers such as the Malyutka or Ovod type.
Information