The order to develop a new flamethrower tank was issued at the beginning of December 1942. In addition to the medium tank technology, it was proposed to develop a similar vehicle based on the existing self-propelled artillery. The reasons for the emergence of such a proposal is difficult to understand. The general characteristics of the existing ACS, as well as the proposed appearance of the flame-thrower in combination with the intended method of use could be the reason for serious doubts about the feasibility of building a new technology. Nevertheless, the German command approved the development of a new flamethrower self-propelled gun. The car was named Sturmgeschütz (Flamm) or StuG (Fl).
The Sturmgeschütz III F modification was chosen as the base for the new flamethrowing machine. Such self-propelled guns entered mass production a few months earlier and could become a suitable basis for a new technology. In addition, there is information about the use in the new project of several Ausf.F / 8 chassis, characterized by the presence of enhanced booking. On the frontal details of the hull additional overhead armor plates were installed, which improved the protection performance. With the exception of using additional armor plates, both versions of the base chassis were identical, and in addition, when upgrading them using the new design, the same units were used.
The only surviving photograph of the StuG (Fl) flamethrowing machine. Photo Aviarmor.net
The ACS StuG III was based on aggregates of the medium tank Pz.Kpfw.III, but had a number of serious differences from this machine. First of all, when creating a self-propelled gun, the base building underwent major modifications, which received a large wheelhouse to accommodate the crew and weapons. The overall layout and composition of the main units at the same time remained without significant changes. In front of the hull were transmission units, behind which was placed the fighting compartment of large sizes. The feed contained the engine with the necessary additional equipment.
The frontal part of the self-propelled gun had a complex multifaceted shape, formed by several armor plates of different sizes and shapes. The forehead of the case was protected by three rectangular sheets 50 mm thick (in the F / 8 version an additional 30-mm sheet was also used), the beads and the sterns were made of 30-mm parts. The logging protection parameters were similar to the characteristics of the hull; it was also assembled from sheets of 50 and 30 mm thickness. From above, the crew covered the 10-mm roof.
Self-propelled guns StuG III Ausf.F were equipped with Maybach HL 120TRM carburetor engines with 300 horsepower. With the help of a cardan shaft and transmission units, the engine torque was transmitted to the front drive wheels. The design of the power plant and transmission corresponded to the systems of the base medium tank, which made it possible to ensure a high degree of standardization of serial combat vehicles. In addition, it was possible to move in some combat formations with other equipment.
According to available data, in order to simplify the development and construction of new equipment, it was decided to equip the Sturmgeschütz (Flamm) with a flamethrower designed for the Pz.Kpfw.III (Fl) medium flamethrower tank. Some units of this system had to be refined, in addition, there was a need for some re-assembly and other placement of systems in the combat compartment of the new carrier. At the same time, the main characteristics and principles of work remained unchanged.
In place of the standard 75-mm artillery in the wheelhouse, it was proposed to install a fire engine for throwing flammable liquid. The hose was a construction of the main barrel caliber 14,5 mm and a protective casing-pipe. The task of the latter was to protect the barrel from external influences, as well as, to some extent, camouflage weapons. The installation system of the trunk allowed to direct weapon on 10 ° to the right and to the left from the neutral position, and also to change the angles of vertical pickup from -6 ° to + 20 °.
Inside the fighting compartment were placed tanks for the storage of fire mixture and its subsequent supply to the fire engine. The tanks were equipped with double walls, between which the water from the engine cooling system was supposed to circulate. Using hot water, it was proposed to heat the fire mixture before use, which, according to the idea of the flamethrower developers, was to eliminate liquid thickening at low atmospheric air temperatures and ensure firing in a wide range of weather conditions at any time of the year. It also provided for the supply of hot water to the barrel of a fire engine to warm it up and flush out possible plugs from the cooled and thickened mixture remaining in the channel. In the case of the Pz.Kpfw.III flamethrower tank (Fl), a similar heating system made it possible to shoot at air temperatures down to -22 °.
It was suggested to throw away the fire mixture with compressed air. To this end, a separate balloon was introduced into the flamethrower, connected to a compressor. The work of the latter was provided by a DKW two-stroke engine with an 3 hp power. Before the shot, the compressor had to create air pressure up to 15 MPa, after which, using a special valve, it was possible to throw the combustible mixture through the barrel. The ignition was made using the electrical system on the hoses. The energy of compressed air was enough to emit fire mixture to a distance of up to 50-55 m.
Since the new combat vehicle was created on the basis of self-propelled guns Sturmgeschütz III Ausf.F, the use of additional combat weapons was not provided. If necessary, the crew had to use one MG 34 machine gun of the 7,92 mm caliber, which was stored in the stowage. Unlike the later modifications, the SAU of the “F” model was not equipped with a machine gun mounting system, which allowed it to be used at any time. The crew also had the theoretical possibility to use personal weapons.
The crew of the flame-throwing ACS StuG (Fl), according to various sources, was supposed to consist of four people, but we can assume some of its reduction in comparison with the base machine. In particular, the new combat vehicle did not need a loader, and the functions of the commander and gunner could be transferred to one crew member, as was done in the previous draft of an average flamethrower tank. In this case, the armored vehicle could two or three people.
According to known data, the dismantling of artillery guns and the installation of a flamethrower did not lead to a change in the dimensions of the vehicle in comparison with the basic design. The length of the vehicle remained at the level of 6,77 m, width to 3 m, height - 2,15 m. The combat weight still did not exceed 23,5 t. Saving the weight and the original power plant did not, as expected, change the mobility of the vehicle. The maximum speed was 40 km / h, power reserve - 165 km. The ability to travel over rough terrain with overcoming some obstacles has been preserved.
Scheme flamethrower SAU. Figure Aviarmor.net
When deciding on the development of new self-propelled guns with flamethrowing weapons, it was proposed to build a hundred of these machines. Flame-retardant self-propelled guns should be redone from suitable modifications to the serially produced StuG III. Later plans were revised upwards. By the summer of 1943, the command wanted to get already 220 flamethrower machines based on self-propelled guns. However, all these plans were never fulfilled. The limited capabilities of the industry have had a great impact on the actual pace of assembly.
Modernization of serial self-propelled guns on the new project began in May 1943 year. To install a flamethrower system identified nine cars modifications Ausf.F. In June, another Sturmgeschütz III was sent to rework. Removing unnecessary equipment with the installation of new equipment did not take much time. By mid-June 10 flamethrower self-propelled guns were ready for testing and subsequent transfer to the customer. 23 June, all ten cars were loaded onto railway platforms and sent to the troops.
As far as we know, all ten StuG (Fl) vehicles were consolidated into one company and transferred to the jurisdiction of one of the divisions operating on the Eastern Front. Any information about the combat work of self-propelled guns and the effectiveness of their use are missing. However, it is known that in July 43-nd one of the cars for some reason caught fire, but the fire was extinguished. The survey showed that the self-propelled gun is subject to recovery. Soon she was sent to the rear for repairs, which ended in September. Then, the repaired car was returned to the troops, which continued its operation.
Apparently, the combat effectiveness of ten new flamethrower self-propelled guns left much to be desired. As a result, in January 1944, all Sturmgeschütz (Flamm) were sent to the factory. Further operation of this technology in its original form, due to its low characteristics, was considered inexpedient. Since the used chassis has not yet developed its resource, it was decided to rebuild the flamethrower self-propelled guns on the original projects. Flamethrowers and all their units were removed from them, instead of which they mounted standard guns, styling for projectiles, etc. On this история project StuG (Fl) is over. Until our time did not survive a single instance of such technology.
The reasons for the fairly quick refusal of self-propelled installations StuG III with flamethrower armament are simple and understandable. This combat vehicle was distinguished by extremely low combat qualities and dubious survivability when confronted with an enemy. A characteristic feature of all flamethrower tanks of that time, including the Sturmgeschütz (Flamm), was a short range of firefighting, not exceeding a few tens of meters. This made the combat vehicle, when carrying out the attack, approach the target for a minimum distance, which made special demands on protection and additional armament.
Reconstruction of the appearance of the StuG (Fl) machine. Figure Rtvmodelismo.com
The available 50-mm frontal armor of the base self-propelled gun (even when reinforced with an additional sheet 30 mm thick) at distances of several tens of meters could break through with various Soviet-made tools, which could seriously impede its progress towards the goal. In this case, only one successful hit of an artillery shell could lead to the ignition of the fire mixture and the destruction of the vehicle with the death of the crew.
In addition, there was no weapons to protect the enemy from infantry: the only machine gun should be stored in the installation, and any mechanisms to install it with constant combat readiness were not used. It should also be noted insufficient angles aiming flamethrower, which could make it difficult to hit targets. The horizontal guidance sector, which is only 20 ° wide, in turn, seriously hampered possible self-defense from infantry using a flamethrower.
As a result, the flamethrowers on the battlefield needed additional cover with armored vehicles and infantry, which could protect them from possible threats arising when advancing to enemy positions. It should be noted, given the firepower and combat effectiveness of such a cover, the need to use a flamethrower machine could be questionable. In other words, tanks and infantry could themselves fight without resorting to the help of flamethrower StuG (Fl).
According to the results of short and not very successful operation, which also led to the temporary disabling of one of the machines, all ten flamethrower-powered self-propelled guns Sturmgeschütz (Flamm) were sent to the rear for rework on the basic project. Soon they returned to the front as self-propelled guns with artillery pieces, which could actually be useful for the troops. The next project of the self-propelled machine with a flamethrower weapon ended in nothing. Nevertheless, the German specialists did not abandon this direction and later tried to create several more combat vehicles armed with flamethrowers.
Chamberlain P., Doyle H. Complete reference book of German tanks and self-propelled guns of the Second World War. - M .: AST: Astrel, 2008.