The development of the Flakpanzer IV Ostwind self-propelled gun started in early 1944, almost simultaneously with the design of the Wirbelwind machine. The reasons for the appearance of this project were simple - the military wanted to get an anti-aircraft gun with increased efficiency. The combat experience of anti-aircraft units showed that 20-mm automatic guns, including on quad installations, allow you to fight aviation enemy, but in terms of firepower noticeably inferior to 37 mm systems. Thus, to supplement or even completely replace the Wirbelwind self-propelled gun with four 20 mm guns, it was proposed to create a new machine with a more powerful weapons.
ZSU Ostwind. Photo by Panzerpedia.wikia.com
Having studied the requirements of the customer, the Ostbau plant began to create a new combat vehicle. In order to simplify the project and accelerate the development, as well as to maximize the cost of production and operation, it was decided to use the already developed approach. The basis of the new armored vehicle was to be the chassis of the existing medium tank Pz.Kpfw.IV of any of the later modifications. It was necessary to remove the turret from the tank, instead of which a new armored vehicle with anti-aircraft armament was to be mounted. A similar approach was already used in the construction of anti-aircraft self-propelled guns and allowed to solve all the tasks with maximum efficiency.
The proposed use tanks as a base for the new self-propelled Pz.Kpfw.IV. To simplify the production of ZSU and reduce industry burden, it was decided not to use the new chassis of special construction. For construction machines Ostwind plant-collector had to use existing tanks in the army. Damaged or in need of repair equipment was proposed to send to the rear, restore and convert to self-propelled self-propelled guns. A similar approach was used in other projects of anti-aircraft combat vehicles.
According to reports, the Ostvind production vehicles were built on the basis of Panzerkampfwagen IV tanks Ausf.H. It was the penultimate serial modification of the armored vehicle, which differed from the previous ones in increased characteristics. In particular, this modification provided for the most powerful booking among other versions of the tank, and in addition, an 300 hp engine was used.
During the construction of ZSU Ostwind base chassis had to undergo minor changes. From the base tank, it was necessary to remove the turret with weapons, as well as remove the equipment of the combat compartment necessary for using the machine in its original quality. Despite this, the main features of the machine remained the same, which, in particular, made it possible to maintain performance at the required level.
Tank Pz.Kpfw.IV was a fairly successful base chassis for various vehicles. This car had a standard layout for a similar German design with a front-mounted transmission and aft engine compartment, between which there was a command compartment and a fighting compartment. Under the crew compartment floor held propeller shaft connects the engine to the transmission.
In the case of tanks modified Ausf.H basis of the power plant was a Maybach HL 120TRM gasoline engine with horsepower 300 hp. Through the driveshaft, the torque was transmitted to the main clutch and the six-speed main gearbox. The transmission also included a planetary turning mechanism, final drives and brakes. With all these units, the front wheels were rotated.
The base of the tank's chassis was eight small diameter road wheels on each side, interconnected in pairs and equipped with suspension based on leaf springs. The drive wheels were located in the front of the sides, the guides - in the stern. The most notable difference in the chassis of the Pz.Kpfw.IV Ausf.H tank from other modifications was the use of three support rollers without rubber bands.
The hull of the tank was made of armor plates with a thickness from 10-15 mm (roof and bottom) to 80 mm (front sheet). Such protection allowed the armored vehicle to withstand the hitting of the shells of some enemy guns. It was assumed that the preservation of such protection will allow the prospective self-propelled gun to work in some combat formations with tanks on the basis of a similar chassis.
Anti-aircraft gunner with a clip 37-mm shells for the gun FlaK 43. Photo of Wikimedia Commons
On the existing tower chase, the Ostwind project proposed to mount units of a new design. The new tower for anti-aircraft armament consisted of a lower support sheet with devices for mounting on the chase and a large hole in the center, as well as several side sheets. For the new self-propelled gun, the tower was designed hexagonal in shape with sides consisting of two parts: the lower row was installed with the collapse outward, and the upper leaned inward. This made it possible to reduce metal consumption, reduce the mass of the structure and ensure the maximum possible internal volume. In addition, due to the polygonal shape of the tower did not extend beyond the roof of the hull and did not impose restrictions on the transportation of equipment. At the junction of the front hull sheets, there remained a small slot for moving the gun. For the construction of such a tower it was proposed to use 25-mm armor plates. The roof was not provided. For its characteristic appearance, the new tower received the unofficial name of Keksdose - “Baking dish”.
Inside the new tower, it was proposed to mount an installation for an anti-aircraft gun of caliber 37 mm. In order to simplify the project, Ostbau specialists took an existing 3.7 cm FlaK 43 gun with a ready-made carpet and modified the latter for installation on a self-propelled chassis. Minor modifications of the gun mount made it possible to provide circular guidance of the gun horizontally. Vertical guidance was carried out in the range from -7 ° to + 90 °. Carriage guns kept armor plate, which is now proposed to use as a mask. His task was to protect the guns and gunners from accidental hits in the front section of the tower.
The FlaK 43 gun had an 37-mm barrel with a length of 57 caliber and was equipped with automatic based on the removal of powder gases. The gun used the clips for eight 37x263 mm B shells, which is why the practical rate of fire did not exceed 150 rounds per minute at a technical level of 250. Depending on the type of projectile, the weapon could provide its initial speed up to 800-820 m / s, which allowed the enemy aircraft to attack at distances up to 4-4,2 km. When firing at ground targets, the maximum effective range exceeded 6 km.
As an auxiliary weapon designed to combat the enemy's manpower, the ZSU Ostwind received (or rather, retained) the MGNNXX 7,92-mm machine gun in the frontal installation of the hull, in the workplace of the gunner-radio operator. The crew also had a second machine gun, which had to be transported in stowage and removed only when necessary.
To manage the new self-propelled gun had a crew of five. The driver and radio operator were located in the building, in the control room. The use of guns was the task of the commander, gunner and loader, placed in the tower. They were supposed to search for and detect air targets, as well as aiming a cannon and firing. The duty of the loader was to work with shell clips. According to reports, a total of 125 clips with 1000 shells were transported in the Ostwind package.
Replacing the existing tower with a new unit made it possible to keep the weight and dimensions of the machine at about the old level. The combat weight of the East Wind was set at the level of 25 t, the length did not exceed 6 m, the width was 3 m, but the height had grown to 3 m. per ton. Due to this, the maximum speed on the highway could reach 300-12 km / h with a power reserve of up to 38 km.
The development of the Flakpanzer IV Ostwind project ended in the early summer of 1944. By the beginning of July, on the basis of the tank that was available, the first prototype was built, which soon came to the test. The use of ready-made units has significantly accelerated all the necessary checks, as well as determine the future fate of the new development. In July (according to other data, in August) 1944, the company-developer ordered the construction of hundreds of new anti-aircraft self-propelled guns. It was also planned to organize the transfer of repaired chassis arriving in the rear, with the aim of assembling new equipment.
The Ostwind self-propelled gun was adopted under the designation 3.7cm FlaK 43 auf Pz.Kpfw.IV - “Flak 43 cannon on the chassis Pz.Kpfw.IV”. In addition, in some sources there are other machine designations, such as Flakpanzer IV / 3.7cm FlaK, Gerät 582, etc.
Armored car at the front. Cannon raised to maximum angle of elevation. Photo Aviarmor.net
Construction of the first batch of ZSU Ostwind began in July 44 th. However, for various reasons, these 15 self-propelled guns were transferred to the customer only at the end of the year. By the spring of 1945, about three dozen cars were built and handed over to the customer. Shortly after the transfer of this party production was stopped. The anti-Hitler coalition developed the offensive, because of which the German industry was constantly losing certain enterprises, and also was deprived of the opportunity to fulfill the orders already received. Thus, after March 1945, Ostbau did not complete a single new type of anti-aircraft self-propelled guns. The overall release was limited, according to various sources, to 43-46 machines.
According to some sources, during operation at the front, the Flakpanzer IV Ostwind self-propelled anti-aircraft installations manifested themselves ambiguously. Relatively powerful 37-mm guns allowed them to fight with low-flying enemy aircraft and protect their troops from air strikes. Nevertheless, there were also serious shortcomings, caused, first of all, by the extremely small number of equipment. Less than fifty self-propelled guns could not be reduced to full anti-aircraft units that can have a significant impact on the course of hostilities. The distribution of the existing machines between the various units of the army, in turn, did not allow to fully solve the tasks of air defense.
Because of the impossibility of proper organization of the combat work, the Ostwind self-propelled guns caused some damage to the Allied aviation, however, they themselves often became the target of the strike and received serious damage, including fatal damage. From this point of view, the first prototype of the machine, in the middle of December 1944 of the year operating in the Ardennes in the order of military trials, looks like a real lucky one. Despite all the fierce battles, this machine managed to do without serious damage and in general, return to the factory. Other self-propelled guns were less fortunate - they were all destroyed or disposed of soon after the end of the war.
At the end of 1944 of the year, when the troops were just beginning to develop Ostwind, the developer company proposed several projects for the modernization of such equipment, aimed at improving some of the characteristics of simplifying its release. The first project involved the replacement of the FlaK 43 gun with a paired 3.7 cm Flakzwilling 43 installation based on two such guns. The use of such weapons can significantly increase the firepower and effectiveness of self-propelled guns. The new project received the symbol Ostwind II. In the case of adopting a car could designate as 3.7cm Flakzwilling 43 auf Pz.Kpfw.IV.
Anti-aircraft installation 3.7 cm Flakzwilling 43, proposed for installation on the ZSU Ostwind II. Wikimedia Commons Photos
Also, at the request of the military, a project was developed to install a turret with an 37-mm cannon on the chassis of the Panzerkampfwagen III tank. Such a project allowed the use of existing chassis, no longer able to fully perform the functions of the base for the tank. In addition, it was possible to ensure the release of anti-aircraft armored vehicles in relatively large volumes.
In January 1945, Ostbau was ready to build the first prototype ZSU with twin implements. In addition, at that time, the assembly of the first prototype self-propelled gun on the basis of the Pz.Kpfw.III tank could begin. Even before the construction of the prototypes of both machines, it was decided to start the mass production of such equipment. Over the next few months, the Ostbau plant was to build an 100 self-propelled Ostwind II and 90 vehicles based on the Pz.Kpfw.III chassis with a Keksdose turret and one 37-mm gun. However, at the beginning of 1945, Nazi Germany could not even count on stabilizing the situation on the fronts. As a result, many construction projects of one or another equipment, including new versions of the Ostwind ZSU, stopped at one or another stage. As far as is known, the contractor did not have time to build a single machine of new modifications.
Despite all the efforts of designers and production workers, the Flakpanzer IV Ostwind self-propelled self-propelled units, as well as other machines of this family, could not fully solve the task. In about nine months of production, it was possible to build and transfer to the troops less than fifty such machines, which was too little to fully cover the troops using self-propelled guns. As a result, another project led to noticeable waste of time, effort and resources, but did not produce the expected results and brought the defeat of Germany closer.
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