After the Great Patriotic War, work on samples of weapons and military equipment for the Airborne Forces was widely developed in our country. If we talk about armored vehicles, the main efforts were focused on creating an anti-tank self-propelled artillery installation. One of the first to start solving this problem was the Special Design Bureau under the Engineering Committee of the Ground Forces (OKB IC SV) under the leadership of Anatoly Fedorovich Kravtsev.
The lightly armored "self-propelled amphibious installation K-73" (or "amphibious airborne self-propelled artillery installation ASU-57P") was developed at the IK Design Bureau in parallel with the K-75 armored personnel carrier. In 1949, the first prototype of the vehicle was manufactured at the GBTU Military Repair Plant No. 2 (Moscow). The second prototype was intended for artillery tests at GNIAP GAU. A version of the ASU-57PT was designed, but was not implemented in metal, which was also intended for towing artillery systems.
For self-propelled artillery mount K-73 (ASU-57P) open type A. F. Kravtsev chose a layout with a front power plant and aft - combined fighting compartment and control compartment.
The riveted-welded hull was open at the top and covered with a removable tarpaulin awning. The front edge of the awning could be lifted for a better view of the area. The frontal hull plates were made: the upper one was made of 8-mm steel (the angle of inclination was 42 '); medium - made of 6 mm steel (inclination angle - 25 '); bottom - made of 4 mm steel (angle of inclination - 45 '). Side steel sheets with a thickness of 4 mm were installed vertically. The bottom thickness (duralumin sheet) was 3 mm. The vertical rear wall with a thickness of 1.5 mm and the fenders were made of duralumin. All hatches were fitted with rubber gaskets to seal the vehicle.
In the bow of the hull there was a wave-breaker shield made of duralumin. When the SPG was moving overland, the flap turned and pressed against the body. To reduce the ingress of atmospheric air into the post-screw stream of water, on the rear wall of the hull there was a duralumin swivel flap of the propeller, which was lowered when the machine entered the water.
A six-cylinder carburetor engine from a GAZ-51N truck with its fuel supply, lubrication, cooling and starting systems was used as a power plant. The power plant was separated from the control compartment and the fighting compartment by a partition.
The fuel tank was located to the left of the engine, was made of duralumin and protected with 8-mm special rubber, which prevents gasoline from flowing out in the event of a bullet piercing the tank. 70 hp engine (51 kW) ensured the maximum speed of movement on land 54 km / h, and afloat - 7, 8 km / h. The engine was started using an electric starter. Ignition system - battery. To facilitate starting the engine at low temperatures, a boiler-heater from a GAZ-51 car served. The K-73 (ASU-57P) cruising range reached 234 km on the highway, 134 km on bumpy dirt roads, and 46 km afloat.
When the car moved overland, the air that cooled the radiator entered through the air intake hatch in the front part of the roof of the case above the radiator and, with the help of a fan, was removed from the engine compartment through the left and right air ducts with louvers. When afloat, the air intake hatch was hermetically closed by flaps, the air ducts were raised (to exclude the ingress of seawater), and air intake for cooling the engine compartment was carried out from the fighting compartment by a fan.
The first sample of the self-propelled unit K-73 (ASU-57P) on trials in 1950
K-73 (ASU-57 P) with a raised wave-reflecting shield.
The mechanical transmission consisted of: the main dry friction clutch (ferrodo steel); three-way, four-speed gearbox; main gear; two high-quality clutches with floating band brakes; two single-stage final drives; main and side driveshafts. The main clutch (clutch), gearbox (with the exception of the gearbox shaft hubs) and the driveshaft joints were borrowed from the GAZ-51.
Maneuvering of the K-73 afloat was carried out by the driver using the steering wheel. In this case, a horizontal deflection of a three-blade propeller was carried out through the drive, which was installed on the outer rotary part of the shafting, mounted on the rear wall of the machine body. The deflection of the shafting with the screw provided the working angle of rotation of the machine 24 '. When driving overland, the outer part of the shafting with a screw was retracted into a special niche located on the left (in the direction of travel) in the rear wall of the body.
The suspension of the car was individual, torsion bar, with hydraulic shock absorbers at its last nodes. The hydraulic shock absorbers had the same design as the shock absorbers of the ZIS-110 passenger car. The tracked propeller consisted of six single-disk road wheels with external shock absorption, two idler wheels, two cast driving wheels of the stern arrangement and two fine-link tracks with a pinned engagement. The average specific ground pressure was 0.475 kg / cm2.
K-73 could overcome a vertical wall with a height of 0, 54 m and a ditch with a width of 1, 4 m. The maximum angles of ascent and descent were 28 '.
General view of the self-propelled unit ASU-57PT (draft).
Placement of the main ASU-57P units.
1 - gas tank; 2 - engine; 3 - radio station; 4 - the main clutch; 5 - gearbox; 6 - commander's seat; 7 - driver's seat; 8 - front ammo rack; 9 - loader's seat; 10 - rear ammo rack; 11 - side cardan shaft; 12 - main gear; 13 - screw; 14 - side clutch.
The K-73 crew consisted of three people. The driver's workplace was located to the right of the cannon, behind it was the loader's workplace, to the left of the cannon - the vehicle commander (aka the gunner). The fighting compartment was covered from above with a removable canvas awning. The driver observed the terrain through a viewing block in the frontal hull sheet and a viewing slot in the right side of the vehicle's hull. In a combat situation, the commander watched the terrain through the viewing slots in the frontal and side hull sheets.
The main weapon of the K-73 was the 57 mm 4-51 cannon, equipped with an effective slotted muzzle brake to reduce recoil, which was especially important when firing from the water. The gun was installed in a special welded frame welded to the sides of the hull. According to the terms of the layout, the gun was displaced to the left by 100 mm relative to the longitudinal axis of the vehicle. The height of the line of fire was 1160 mm. The auxiliary weapon was a 62-mm SG-43 machine gun paired with a cannon 7. In addition, the vehicle included a 7.62 mm PPS submachine gun, F-1 hand grenades and an SPSh signal pistol. When firing from a twin installation, an OP2-8 telescopic sight was used. The vertical aiming angles of the paired installation were in the range from -4 * 30 'to +15', horizontally - in the 16 'sector. The guidance of the paired installation was carried out using mechanisms with a manual drive. Sighting rate of fire from the gun reached 7 rds / min. To mount the 4-51 in the stowed position, there was a special stopper and struts. The cannon was released from the commander's seat using a cable drive.
Ammunition for the gun consisted of 30 rounds with armor-piercing subcaliber, armor-piercing and fragmentation shells, ammunition for a machine gun - from 400 rounds, for a submachine gun - 315 rounds, for a signal pistol - eight signal cartridges. Eight hand grenades were housed in two structures.
The first sample of the self-propelled unit K-73 (ASU-57P) on trials in 1950
K-73 (ASU-57P) was adapted for parachuting on a platform separately from the crew and for landing with a Yak-14 glider.
For communication, a 10-RT-12 radio station and a TPU-47 tank intercom were used.
The electrical equipment was made in a single-wire circuit. The voltage of the on-board network is 12 V. Two ZSTE-100 storage batteries and a GT-1500 generator were used as power sources.
To extinguish the fire, the car had an OU-2 carbon-acid fire extinguisher.
External communication was carried out using the YURT radio station.
In accordance with the order of the Minister of War of the USSR of February 11, 1950, at the NIIBT proving grounds, from April 1 to June 5, 1950, field tests of a prototype of the ASU-57P airborne installation took place. The testing commission was headed by Major General of the Engineering Tank Service N. N. Alymov (Deputy Chairman of the Commission - Major General of Tank Forces B. D. Supyan). The engineering committee was represented by engineer-colonel A. F. Kravtsev.
Tests of the prototype ASU-57P were carried out according to the program approved by the head of the GBTU CA. The purpose of the tests was:
- determination of the tactical and technical characteristics of the prototype and their compliance with the tactical and technical requirements;
- evaluation of the design of the prototype and determination of the reliability of individual units and mechanisms, the convenience of their installation, dismantling and maintenance, as well as conducting preventive inspections;
- determination of the effectiveness of fire on various targets by shooting from a place and on the move, convenience of firing and rate of fire, reliability
nobility of mounting parts of the artillery system, sighting devices and a machine gun, the effect of a shot on the stability of the gun mount, the effect of a muzzle wave on the crew;
- determination of the possibility of forcing water obstacles on the move in various conditions of the state of the coast and coastal areas;
Sea trials were carried out at the testing base of the Polygon, and floating tests were carried out at the Pirogov reservoir and the river. Moscow. Determination of the angles of entry into and exit from the water was carried out on the river. Moscow, near the village of Agafonovo.
General view of the self-propelled gun ASU-57PT with an 85-mm cannon in tow (draft).
During the tests, the ASU-57P traveled 1,672 km on land, of which on the highway - 500 km, on dirt roads - 1102 km, off-road - 70 km. We covered 104 km afloat.
In the conclusion on the field tests, it was said that the prototype of the airborne amphibious self-propelled artillery installation ASU-57P designed by the OKB at the IR SA basically meets certain tactical and technical requirements. Within a run of 1000 km, the units and assemblies of the ASU-57P have shown themselves to be reliable in operation. The most significant deviations from TTT included an excess of weight by 90 kg (3340 kg instead of 3250 kg), the absence of a mechanical pump for pumping water and an easily removable device to improve cross-country ability.
In addition, in a number of parameters, the ASU-57P surpassed the last model of a machine of this type, the ASU-57, designed by plant # 40, which was tested in 1949. Compared with the ASU-57 at factory # 40, the machine designed by the OKB at IK SV had the following advantages:
- made floating (while its weight did not exceed the weight of ASU-57 plant # 40);
- had 7, 62 mm machine gun SG-42, coaxial with a cannon;
- was distinguished by a more convenient placement of gun ammunition, which could be increased;
- had better mobility (the average speed on the highway was 48 km / h instead of 26.3 km / chuASU-57);
- had a greater cruising range (234 km on the highway instead of 162 km);
- the engine and the main clutch of the GAZ-51 car were more reliable in operation compared to the specified units of the M-20 car used in the ACS-57;
- equipped with a serial gearbox of the GAZ-51 car (instead of the special one for the ASU-57);
- all road wheels, torsion bars and balance beams were interchangeable;
-the cannon was released by the crew without getting out of the car.
A prototype self-propelled gun K-73 (ASU-57P) after modifications.
The first sample of the self-propelled gun K-73 (ASU-57P). Back view. In the photo on the right: a prototype of the K-73 after modifications. Currently, this vehicle is in the Military-Historical Museum of Armored Weapons and Equipment in Kubinka.
At the same time, the ASU-57P presented for testing had a number of design and production flaws that reduce its combat qualities. The main ones were:
- insufficient body tightness;
- the possibility of penetration into the body of bullets and lead splashes through the embrasures of the cannon, machine gun and sight;
- the presence of stampings in the bottom under the engine crankcase and side clutches;
- insufficient strength of the ammunition rack and mounting parts for the gun;
- the vehicle commander does not have a beveled block for forward observation;
- low reliability of the V-belt transmission of the engine (during the tests, the belts were replaced three times);
- unsatisfactory operation of the engine heating system;
-the impossibility of straight-line movement of the machine afloat;
- lack of a fixed position of the steering wheel in the working range;
- large interference with the reception of radio transmissions due to the lack of shielding of electrical equipment;
- low reliability of lighting devices and auxiliary equipment due to the lack of depreciation.
Summing up the results, the commission considered it expedient to organize the production of an experimental batch of vehicles for military tests, provided that the identified deficiencies were eliminated and positive results of artillery tests were obtained at the State Scientific Research Institute of Aviation and Aviation of the GAU. Although data on the artillery tests could not be found, it is known that they took place and were successful.
From the memoirs of veterans of the OKB IV B. P. Babaytseva and N. L. Konstantinov, it follows that the repeated tests (the navigable qualities were also checked at the Pirogov reservoir) were even more successful than the previous ones. Anatoly Fedorovich Kravtsev, being a master of driving, fully demonstrated to the commission all the advantages of the car.
One of the prototypes of the K-73 self-propelled gun. The propeller rotary shield is clearly visible, mounted on the rear wall of the hull.
A. F. Kravtsev demonstrates the capabilities of the K-73 prototype to overcome water obstacles. [Center]
Loading K-73 (ASU-57P) into the Yak-14M landing glider. 1950 g.
The tests showed that the self-propelled gun ASU-57P designed by the OKB IK significantly surpassed the existing analogue, and the creators naturally hoped for a victory - the adoption of the machine for service. However, these hopes did not come true. By the decree of the Council of Ministers of the USSR (probably, the decree of the Council of Ministers of the USSR dated 12.09.1951 or 16.09.1953), it was decided to transfer all design documentation and a prototype to plant No. 40 - to the KB MMZ, which was headed by N. A. … Astrov. Since September 1951, they have been working there on a floating modification of the ASU-57 self-propelled gun. The first prototype of the floating self-propelled gun "Object 574" (or ASU-57P) was built in November 1952.
One of the prototypes of the K-73 was transferred to the Military-Historical Museum of Armored Weapons and Equipment (Kubinka settlement), where it can still be seen today.
In Kubinka
III International Salon of Arms and Military Equipment "MVSV - 2008"
