Sd.Kfz. 251

There were four main model modifications to the Sd.Kfz. 251 (Ausführung A through D), which formed the basis for at least 22 variants. The initial idea was for a vehicle that could be used to transport a single squad of 10 panzergrenadiers to the battlefield protected from enemy small arms fire, and with some protection from artillery fire. In addition, the standard mounting of at least one MG 34 or MG 42 machine gun allowed the vehicle to provide suppressive fire for the rifle squad both while they dismounted and in combat. The troop compartment was protected by armor on its sides, but open on top. The armour plates were designed to provide protection against standard rifle/ machine gun bullets (such as the 7.92×57mm Mauser). The front-facing plates were 14.5mm thick; the sides were V-shaped 8mm thick plates, steeply angled to increase their effective protection against horizontal fire. This level of armour provided protection against normal (non-tungsten) rifle AP round, which could pierce about 8mm of vertical armour. Positive aspects of the open top included greater situational awareness and faster egress by the infantry, as well as the ability to throw grenades and fire over the top of the fighting compartment as necessary while remaining under good horizontal cover. The downside, as with all armored personnel carriers of the era, was a major vulnerability to all types of plunging fire; this included indirect fire from mortars and field artillery, as well as small arms fire from higher elevated positions, lobbed hand grenades, Molotov cocktails, and strafing by enemy aircraft. The first two models (Ausf. A and B) were produced in small numbers from 1939. Ausf. A and B models can be identified by the structure of the nose armor, which comprised two trapezoidal armor panels - the lower of which had an engine cooling vent. The B model, which began production in 1940, eliminated the fighting compartment's side vision slits. The C model, which started production in mid-1942, featured a simplified hexagonal-shaped forward armored plate for the engine. Models A through C had rear doors that bulged out. The C model had a large production run, but was quite complex to build, involving many angled plates. From early 1943, the D model was developed with the purpose of halving the number of angled body plates, simplifying the design and thus speeding up the production. D models can be easily recognized by their single piece sloping rear, with flat doors, and was the most produced variant, with 10,602 units manufactured. The standard personnel carrier version was equipped with a 7.92 mm MG 34 or MG 42 machine gun mounted at the front of the open compartment, above and behind the driver. A second machine gun could be mounted at the rear on an anti-aircraft mount. Variants were produced for specialized purposes, including with anti-aircraft guns, light howitzers, anti-tank guns and mortars or even large unguided artillery rockets, as well as a version with an infrared search light used to spot potential targets for associated Panther tanks equipped with infrared detectors. A strong design feature of the Sd.Kfz. 251 was the large track area, with the characteristic "slack track" design with no return rollers for the upper run of track. The Sd.Kfz. 251 also had the Schachtellaufwerk system of overlapping and interleaved main road wheels common to virtually all German halftracks of the period. This lowered the ground pressure and provided better traction, at the cost of much greater complexity in maintenance. The Sd.Kfz. 251 had a combination of front wheel and tank steering, where normal steering engaged track braking as increased turning power was required. As with the Tiger I and Panther tanks that shared interleaved and overlapping main road wheels, accumulated mud and snow could clog or freeze solid between them in muddy or winter weather conditions, such as those during a Russian rasputitsa mud season, immobilizing the vehicle. Annual production started slowly and remained below 1,000 Sd.Kfz. 251 per year until 1941. In 1942, 1,190 Sd.Kfz. 251 were produced, while in 1943 the figure rose to 4,250 and in 1944 to 7,800. A total of at least 15,252 vehicles of all versions and variants were built. ==Use==