By the time of the attack on the Soviet Union in the army of Nazi Germany, there were a significant number tanks different types armed with a 7,5 cm KwK 37 L / 24 gun. The first months of the war showed that a gun with a relatively short barrel has very limited potential in the fight against enemy armored vehicles. The result of this was the beginning of the development of new modifications of tanks with long-barreled guns. Available guns with insufficient characteristics, in turn, was now proposed to be used on a different technique. By the beginning of 1942 there was a proposal to install such weapons on light and medium half-track armored personnel carriers.
Reconstruction of the appearance of the BRM Sd.Kfz.251 / 9 first version. Figure Tanks-encyclopedia.com
The proposal to build light self-propelled guns based on the BTR had some positive aspects. For example, it was expected a significant reduction in the cost of finished equipment in comparison with the "full-fledged" ACS. At the same time, a part of the combat characteristics of such equipment should have been at the same level. As a result, the original proposal was approved. The army has launched several new projects in which two types of armored personnel carriers were to be used: light Sd.Kfz.250 and medium Sd.Kfz.251.
One of the first such projects involved the modernization of a medium semi-tracked armored personnel carrier with rearmament, involving the use of 75-mm gun. Such a combat vehicle received the symbol Sd.Kfz.251 / 9, denoting the serial number of development based on the existing chassis. In addition, the alternative name was used Gerät. The army assigned the name mittlerer Schützenpanzerwagen mit 7,5 cm KwK 37 to the armored vehicle - "Medium armored vehicle with an 75-mm KwK 37 cannon." Interestingly, for some reason, the new model was called the military reconnaissance vehicle, and not self-propelled artillery. Nevertheless, the resulting combat vehicle had the characteristic features of the equipment of both classes.
Prospecting machine based on the later series chassis. Photo of Chamberlain P., Doyle H. "Complete reference book of German tanks and self-propelled guns of the Second World War"
The half-tracked armored personnel carrier Sd.Kfz.251 entered the series in the middle of the 1939 year. This machine was originally intended for the transport of infantry, accompanying tanks. In the future, it became the basis for several new specialized modifications, obtained by installing this or that additional equipment. In the case of the Sd.Kfz.251 / 9 project, the 75-mm gun should have been such additional equipment.
The armored personnel carrier was equipped with a body of relatively thin armor, providing protection from bullets and shrapnel. Armor thickness varied from 14,5 mm (hull forehead) to 8 mm (bead and stern). The hull was divided into two main parts: the motor and habitable compartments. The engine and associated units were placed under the front armored hood, formed by a sloping front sheet and a roof of three parts. On the side there were sloping sides. The engine compartment abruptly passed into the habitable compartment with the reservation of a complex shape. The lower part of the sides was installed with the collapse outwards, while the upper parts were tilted inward. Between the lower part of the body and the fender, drawers could be mounted for the transportation of property. The stern sheet was mounted with a slope backwards.
Civilians inspect abandoned BRM. Photo Worldwarphotos.info
Under the hood of an armored personnel carrier there was a Maybach HL 42TURKM carburetor engine with 99 hp power. Behind the engine were placed mechanical transmission units, including a planetary gearbox, providing four forward speeds and one reverse. The transmission linked the engine and drive wheels of a tracked propulsion unit.
Armored Sd.Kfz.251 had a semi-tracked undercarriage, consisting of two main elements. In front of the hull a single wheel axle with spring suspension was attached. The wheels were connected to the steering system and used for maneuvering. As part of the tracked propulsion unit, there were three rows of road wheels of a chess arrangement with an individual torsion suspension. In the inner and outer rows of the chassis there were three rollers, on average - four. The drive wheels were placed in the front of the track, the guides in the rear. For turning at a small angle, the undercarriage used swiveling front wheels. Steeper turns were carried out with the help of steering wheels and the redistribution of power to the drive wheels.
Sd.Kfz.251 / 9 and its crew. Photo Worldwarphotos.info
In the basic configuration, the armored personnel carrier was operated by a crew of two, located in front of the habitable compartment. The crew could monitor the situation with the help of two viewing devices in the front plate and two hatches in the sides. Other habitable volume was given for the placement of the landing. There were two long benches near the sides, on which ten soldiers could fit. Get inside the car followed through large swing doors in the stern. Also, fighters could parachute through the side, taking advantage of the lack of a roof.
Initially, the Sd.Kfz.251 armored personnel carrier was armed with only one or two MG 34 machineguns. Subsequently in the composition weapons machines could be used MG 42 machine guns. One of the machine guns mounted on the front of the installation, located on the front of the hull. In some versions of the BTR, the front machine-gun installation was equipped with an armored shield. Also, some of the machines were equipped with aft machine gun installation.
Sd.Kfz.251 / 9 later version reconstruction. Figure Tanks-encyclopedia.com
The need to install an 75-mm KwK 37 gun, required by the customer, affected the design of the base machine. To mount a relatively powerful weapon with a corresponding recoil impulse, we had to change the design of the existing body, adding some new details to it and changing the existing ones. After analyzing the various mounting options for the gun, it was decided to place the gun in front of the habitable compartment using the front sheet embrasure.
In connection with the installation of a new gun, it was necessary to change the design of the front plate of the hull, equipped with viewing devices. The left side of this part remained unchanged, and the right has lost the viewing door with a lid. In addition, in the center and to the right there appeared a rectangular opening, necessary for the withdrawal of the gun mount. To the right of the control post with the place of the driver appeared attachment systems guns. On top of them was installed armored shield with an embrasure, prominently protruding above the roof of the hull. In two embrasures should have been placed the gun barrel with a set of additional equipment.
The tank gun 7,5 cm KwK 37 had a barrel length 24 caliber and could use several types of ammunition for different purposes. To defeat protected targets, it was originally proposed to use an armor-piercing projectile with an initial speed of 385 m / s, capable of penetrating 35 mm from a distance of 1 km. Subsequently, cumulative projectiles appeared with an initial velocity of 450 m / s and a penetration rate of up to 75-100 mm.
In the Sd.Kfz.251 / 9 project, it was proposed to install a tool with wheel chocks on a stand installation of the original design. One of the characteristic features of the new gun installation was a box-shaped barrel casing, the use of which entailed a change in the frontal part of the hull. Using hand drives, the gunner could fire within a horizontal sector of width 24 ° with elevation angles from -10 ° to + 12 °. The gun was equipped with a Sfl.ZF1 type sight. Inside the fighting compartment, equipped on the spot of the landing compartment of the base armored personnel carrier, it was possible to place the styling for 52 unitary projectiles.
Self-propelled gun / combat reconnaissance machine retained aft installation for a machine gun. In addition, another MG 34 or MG 42 machine gun could be transported in styling. The total ammunition of two machine guns exceeded 2 thousand rounds. With the help of these weapons, the crew had to fight against unprotected targets at short distances or to self-defense from enemy infantry.
To manage the mittlerer Schützenpanzerwagen mit 7,5 cm KwK 37 combat vehicle was a crew of five. The driver remained in the front of the hull. Four other crew members - the commander, the gunner and two loaders - were placed in the fighting compartment and were responsible for the operation of the gun.
During the modernization of the new project was able to maintain some dimensions of the original armored personnel carrier. However, in other parameters, the ACS / BRM should have been different from the base machine. The length of Sd.Kfz.251 / 9 was 5,8 m, width - 2,1 m. Due to the appearance of a gun mount with armor above the body level, the vehicle height increased from 1,75 to 2,07 m. The combat weight of the base BTR was 7,8 t, the machine with artillery installation - 8,53 t.
Armored car in the museum of Kubinka. Photo Armor.kiev.ua
A slight increase in combat mass while maintaining the existing power plant and chassis allowed to do without significant losses in mobility. With a power density of at least 11,6 HP per ton the new self-propelled guns could reach speeds of up to 50 km / h. Cruising reached 300 km. Opportunities to overcome various obstacles remained.
Due to the widest use of ready-made components, the development of the “Medium Armored Vehicle” project did not take long. Already in June, the German industry presented to the 1942 for testing two prototypes. After a brief field test, two units of Sd.Kfz.251 / 9 went to the Eastern Front to check in real armed conflict. Apparently, the prototypes showed themselves well at the front, resulting in an order for the assembly of the 150 serial ACS / BRM that appeared soon.
Soon after the appearance of a full-fledged order, a massive redesign of serial armored personnel carriers began, which involved the installation of 75-mm short-barreled tank guns. Ready combat vehicles were delivered to the troops and entered into service with various pancergrenadier units. Basically they were intended to increase the firepower of units using the standard Sd.Kfz.251 armored personnel carriers.
According to various sources, the fulfillment of the purchase order for the Sd.Kfz.251 / 9 machines continued until the end of 1943 of the year or until the beginning of 44. After this, a new version of the project appeared, which was distinguished by a different design of the gun mount. As it turned out, the units proposed in the first project did not provide the required ease of production. Because of this, it was decided to use other systems. The K51 (Sf) product based on the 7,5 cm KwK 37 cannon was selected as a new weapon.
It was decided that the previously used modifications of the frontal part of the body do not make sense and only complicate the production of the required equipment. System K51 (Sf) allowed to get rid of such shortcomings. When using it directly on the front of the habitable compartment should have been mounted armor design, consisting of a frontal sheet with an embrasure and additional side panels. In the front sheet was mounted installation with a gun KwK 37. Such an alteration of the project allowed to preserve the main characteristics and also to get rid of the need for a serious restructuring of the front part of the habitable compartment.
In 1944, the production of Sd.Kfz.251 / 9 combat reconnaissance vehicles with new weapons was mastered. Shortly after the start of a full-fledged service, this technique received the unofficial nickname Stummel for its characteristic appearance of a short-barreled gun. Subsequently, this name began to be applied to other variants of self-propelled guns based on semi-tracked armored personnel carriers with KwK 37 guns.
Half-track reconnaissance vehicles / self-propelled guns based on Sd.Kfz.251 armored personnel carriers were produced for some time and were actively used by the troops. However, the number of such vehicles in the troops is constantly changing. Plants sent to the front more and more new cars, and the enemy constantly reduced their number. As it turned out during the operation in the military, semi-tracked vehicles with 75-mm cannons can significantly increase the firepower of infantry units, but on the battlefield are exposed to the most serious risks. Poor bulletproof reservation could not protect Sd.Kfz.251 / 9 from artillery or enemy tanks. The power of the guns, in turn, did not always allow firing from a relatively safe distance.
Such combat potential of armored vehicles led to the fact that a significant number of mittlerer Schützenpanzerwagen mit 7,5 cm KwK 37 BRM / ACS did not survive to the end of the war. After the capitulation of Nazi Germany, the few remaining cars were out of work. In the future, most of them went to the cutting as unnecessary. According to reports, only four copies of the Sd.Kfz.251 / 9 self-propelled guns have survived to this day. Three cars of this type in the first version are stored in German Münster, Russian Kubinka, as well as in one of the private collections in the UK. The museum in American Fort Benning has a K51 (Sf) machine on display. Another interesting specimen is available in the National Museum of War and the Resistance Movement of the city of Overlona (the Netherlands). It contains a fairly rusted gun mount from Sd.Kfz.251 / 9 of the first version.
The mittlerer Schützenpanzerwagen mit 7,5 cm KwK 37 or Sd.Kfz.251 / 9 project was one of the first attempts to equip the existing medium armored personnel carrier with a relatively powerful tool. The result of the project was the emergence of an interesting combat vehicle capable of supporting the troops. However, due to the ambiguous ratio of protection and firepower, as well as due to the small number of such combat vehicles could not have a significant impact on the course of the fighting. At the same time, the Sd.Kfz.251 / 9 project launched a whole program to create several armored personnel carrier artillery modifications.
Chamberlain P., Doyle H. Complete reference book of German tanks and self-propelled guns of the Second World War. - M .: AST: Astrel, 2008.