The development of strike aviation in the post-war period posed new complex tasks for the designers of air defense systems. In a minimum time, air targets became faster, more maneuverable and more dangerous, and new systems with appropriate characteristics were required to intercept them. Experts from different countries tried to solve new problems by developing existing ideas and principles, or to create completely new air defense systems. One of the most daring, but fruitless projects of a highly effective anti-aircraft system was proposed by Swedish engineers as part of the 120 mm Lvautomatkanon fm / 1 project.
In the early fifties, high-speed bombers capable of carrying nuclear weapons were considered the main threat. Only one such machine, breaking through to its target, could cause enormous damage, which required the appropriate air defense systems. During this period, the Swedish defense industry had not yet managed to accumulate the necessary experience in the field of missile weapons, which is why it was proposed to solve the task of strengthening air defense with the help of new artillery systems.
Anti-aircraft complex 120 mm Lvautomatkanon fm / 1 in transport position. Photo Strangernn.livejournal.com
The main idea of the new project proposed by Bofors was to create a large-caliber gun with a high rate of fire. It is this combination of the main characteristics that made it possible to obtain high reach in height, acceptable ammunition power and maximum fire density. Several batteries equipped with similar weapons could create a large and dense cloud of debris in the path of enemy aircraft, guaranteeing the defeat of a certain amount of aircraft. To increase the combat potential, the new artillery complex should have been made self-propelled or towed.
The development of a promising air defense system of increased power started at the very beginning of the fifties. The Bofors company, which had extensive experience in the field of artillery weapons, including anti-aircraft ones, was to be engaged in the creation of such a complex. The project was named 120 mm Lvautomatkanon fm / 1 - "Automatic cannon with a caliber of 120 mm, model 1". The designation used fully revealed some of the main features of the project. An alternative designation 12 cm Lvakan 4501 is also known.
It should be noted that the authors of the new anti-aircraft complex were given very difficult tasks. By this time, the Bofors company had already created new projects of rapid-fire guns, but they were talking about ship systems. As a result, not all ready-made ideas and solutions could be used to create a mobile anti-aircraft gun. Most of the main units of the complex had to be developed from scratch.
The high mobility of the anti-aircraft gun turned out to be one of the simplest tasks. For a quick exit to the indicated firing positions, it was proposed to use a towing vehicle and a special wheeled platform. Any suitable tractor equipped with a fifth wheel coupling could tow the platform with the implement. According to available data, after analyzing the available options, the authors of the 120 mm Lvautomatkanon fm / 1 project chose the promising Lastterrängbil 957 Myrsloken three-axle tractor from Scania. With its help, the complex could move along public roads. At the same time, it was impossible to count on obtaining high cross-country ability when driving over rough terrain.
It should be noted that the high performance of the tractor was obtained using some new systems. So, specifically for use in the new project of the anti-aircraft complex, the already developed truck received a boosted engine with a capacity of 200 hp. Subsequently, a different power plant was used on the serial Lastterrängbil 957.
View from a different angle, you can consider the design of the gun mount. Photo Strangernn.livejournal.com
It was proposed to use a special semi-trailer for the installation of the gun mount and its auxiliary means. Its main element was a relatively long, medium-wide platform. According to reports, the internal volumes of such a platform were given for the placement of some of the units used to power the gun mount. In the front part of the platform, a device was fixed to connect to the "saddle" of the tractor. The kingpin was placed in front of a triangular structure with an L-shaped profile. The rear of the semi-trailer had its own chassis. To distribute the large mass of the installation, four dual wheels had to be used. It is noteworthy that all wheels were located in one row, on the trailing edge of the platform. From above, they were covered with a light wing.
There is an image of a modified platform, devoid of wheel travel and a towing device. In this case, hydraulic jacks should have been placed on the sides of the hull, with the help of which the platform rested on the ground.
The central part of the semitrailer platform was intended for mounting the turret of the gun mount. All the necessary support systems and horizontal guidance drives were placed inside the platform body. The gun, along with its support, could turn in any direction. On the rotary device, a turret body with gun attachment systems was placed. The tower had a complex shape formed by a large number of straight and curved surfaces. Its front part had a lower frontal sheet, above which was placed a pair of inclined parts with a set of hatches on each. Between the inclined parts there was a large opening for the tool and related devices. The hull-tower also received vertical sides with large hatches and a vertical rear wall. Apparently, the tower was supposed to be made of armored steel and provide protection against some threats.
In the central opening of the tower there were mounts for the swinging artillery unit. Due to the large size and mass of the gun, it was necessary to use advanced balancing devices, the cylinders of which were outside the protected tower. Between the upper elements of the hull was the casing of the artillery unit, which protruded slightly forward. The rear of this casing protruded beyond the stern of the turret and served as the basis for the installation of two large hulls that contained automatic reloading. The shape of the latter was determined taking into account the need to raise the gun to large elevation angles.
As part of the 120 mm Lvautomatkanon fm / 1 complex, it was proposed to use a 120-mm rapid-fire rifled gun equipped with a 46 caliber barrel. To reduce the negative impact on the base semi-trailer, the barrel had to be equipped with a developed muzzle brake and powerful recoil devices. There is reason to believe that the barrel was also equipped with a protective casing and a liquid cooling system, similar to those used on naval artillery installations.
The complex is in combat and transport positions. Photo by Quora.com
Next to the breech of the gun, a pair of large hulls were placed, which were used by automatic loaders. As conceived by the Bofors engineers, the onboard systems were supposed to independently throw out the empty cartridge case and prepare the gun for the next shot. On the sides of the breech were two large box magazines for 26 shells each. Automation based on mechanical drives, at the command of the operator or independently, had to feed the projectile to the chambering line, and then send it to the chamber. Empty casings were probably thrown out. The type of automation is unknown, but, most likely, it was proposed to use separate systems with electric drives.
According to the available data, the used automatic equipment made it possible to show the rate of fire at the level of 80 rounds per minute. Thus, it took about 30-35 seconds to use up the entire ammunition load. The long barrel accelerated a 35-kg fragmentation projectile to a speed of 800 m / s. At an altitude of 5 km, such a projectile flew for about 8 seconds. The maximum firing range was 18.5 km.
The artillery system was to be controlled from two cabins placed in the turret hull on either side of the artillery unit. For access inside, there were doors on the sides. It was proposed to observe the situation and direct the weapon using hatches in the inclined front plates. In addition, apparently, devices for receiving external target designation should have been located at the operator's workplaces. In this case, several units could work together in certain conditions. In addition to the gunners, the crew of the promising complex was supposed to include a tractor driver.
The anti-aircraft complex 120 mm Lvautomatkanon fm / 1 turned out to be quite large and heavy. In terms of its size, it, in general, corresponded to other equipment based on semi-trailers. The total weight of the installation on the platform is 23-25 tons. Because of this, even a powerful tractor of the Ltgb 957 type could transport weapons only on highways or dirt roads. Effective work on rough terrain was virtually ruled out.
It is known that an important feature of the anti-aircraft complex of the new model was the maximum autonomy of work. After arriving at the firing position, the crew could, as soon as possible, independently complete the deployment and begin combat work. According to some reports, during deployment, hydraulic jacks were installed on the platform, with which it was supposed to be hung in the air, removing the load from the fifth wheel and wheels.
120 mm Lvautomatkanon fm / 1 on the road. Photo Strangernn.livejorunal.com
The installation could, in a minimum time, send a large number of high-explosive fragmentation projectiles to an air target located at an altitude of at least 8-10 km, capable of forming a large field of fragments in its path. After the use of the transported ammunition, a reloading was required, in which it was necessary to use a truck crane and an ammunition transporter vehicle.
At least one prototype of the 120 mm Lvautomatkanon fm / 1 anti-aircraft gun was built in 1954 and launched for testing. There is no detailed information about the checks of such a complex, although there is information about further events. The tests took quite a long time, which is why the project of the artillery system literally waited for the appearance of competitors in the face of missile systems. However, the installation was nevertheless recognized as suitable for operation, however, with certain restrictions. It was decided to build a small serial batch of equipment for subsequent transfer to the troops and use as part of air defense.
According to reports, Bofors soon supplied the Swedish army with 10 anti-aircraft artillery systems with automatic 120-mm guns. At the same time, it is known that Scania was able to build only two Lastterrängbil 957 Myrsloken tractors with increased power engines. Apparently, the remaining eight anti-aircraft guns had to be transported using other vehicles with suitable characteristics. The difference in the basic parameters of such machines could seriously affect the mobility of the complexes.
All ten artillery mounts, combined into one unit, were sent to one of the units in the area of Erebu. There artillery of a new type had to solve the tasks of air defense. Due to the relatively late adoption of the 120 mm Lvautomatkanon fm / 1 complex, it was supposed to be used together with the recently appeared missile systems.
The operation of anti-aircraft systems with 120-mm rapid-fire cannons continued until the early seventies. In 1973, such equipment was considered hopelessly outdated and no longer suitable for full-fledged operation. Already at the time of its appearance, such a technique did not fully meet modern requirements, and after several years of operation, it finally lost its full potential. In addition, all of its tasks could now be solved by new anti-aircraft missile systems.
Most of the built 120 mm Lvautomatkanon fm / 1 installations were sent for disassembly. At the same time, several of these complexes were put into storage. They remained in military units for several decades. Only recently have unique but forgotten specimens been discovered and actually opened to the general public. At least one semi-trailer with a gun mount was donated to the museum. Now it is not in the best condition, but, perhaps, in the future, the most interesting specimen will undergo restoration.
One of the surviving anti-aircraft systems. Photo Raa.se
One of the modernized Ltgb 957 tractors, built specifically for the anti-aircraft complex, later remained in operation. Later, it was this car that was added to the collection of the Arsenalen Museum. The further fate of the second Myrsloken with a redesigned power plant is unknown. Most likely, this machine has exhausted its resource and was cut into metal.
From a technical point of view, the 120 mm Lvautomatkanon fm / 1 project was very successful. The designers of Bofors successfully managed to create a towed anti-aircraft system with a powerful weapon capable of hitting various air targets, including at high altitudes. Nevertheless, such a sample of technology did not fully meet the requirements of its time, which led to a short operation, followed by a natural ending in the form of decommissioning.
The reasons for abandoning the original anti-aircraft gun were quite simple. Moreover, the same factors previously led to the gradual abandonment of the previous large-caliber barreled anti-aircraft systems. High speed, high flight altitude and maneuverability by the mid-fifties managed to become a reliable defense of a strike aircraft from anti-aircraft artillery. To ensure the destruction of the aircraft now required the use of an unacceptably large number of guns and a colossal consumption of ammunition. Taking into account the emergence and development of nuclear weapons, the organization of reliable air defense based on barrel systems turned into a task without a real solution.
By the time the 120 mm Lvautomatkanon fm / 1 project appeared, it became clear that the future of air defense lay in guided missiles. Differing from "traditional" shells in greater cost, they could show an acceptable probability of hitting the target. Further development of this direction made it possible to obtain missiles superior to artillery from both combat and economic points of view.
Progress in the field of anti-aircraft missile systems quickly led to a reduction in large-caliber barreled artillery. In some countries this process was faster, in others it was slower. Nevertheless, all developed armies eventually left barrel artillery only in the land air defense of the near zone. The original Bofors project also fell under this reduction.
However, interesting developments on the 120 mm Lvautomatkanon fm / 1 anti-aircraft gun were not lost. The development company continued to work on promising artillery systems, and used the existing experience. However, now the original ideas were used in the projects of naval artillery. A significant part of such projects has been successfully brought to serial production and operation. But the direction of large-caliber anti-aircraft artillery for the ground forces was finally closed due to the lack of prospects.
