The Panzer IV Medium Tank of World War 2 (1939-1945) became one of the most versatile of the frontline German tanks as its chassis and running gear formed the basis of a myriad of other battlefield designs. One of these became the 3.7cm FlaK auf Fahrgestell Panzerkampfwagen IV (sf) "Mobelwagen" (SdKfz 161/3)) which appeared as a stop-gap Self-Propelled Anti-Aircraft Artillery (SPAAA) platform preceding more improved types in what became the "Flakpanzer" line that appeared before war's end in 1945. These vehicles found success on the battlefronts of World War 2 and endured until the final days of the European Campaign in May of 1945.
The Mobelwagen series was built from battle-damaged Panzer IV tanks which were arriving in droves to German factories from along the Eastern Front and elsewhere. Readily available and with proven running qualities, this stock was reconstituted for the Mobelwagn ("Moving Van") project by Krupp which began in early 1943. The initiative was pressed by the Luftwaffe's inability to provide support for ground forces and key installations against the relentless Allied bombing campaign which covered raids both day and night.
The basic SPAAA design retained much of the traveling function of the Panzer IV tank line. Power was from a Maybach HL 120 TRM 12-cylinder engine outputting 300 horsepower and the driver remained in the hull at the front-right. However, the turret of the original Panzer IV tank was deleted completely and the hull superstructure roof cut into. Atop this structure was added a crude, open-air platform for a gunnery crew, anti-aircraft gun, and mounting hardware. The crew numbered five aside from the driver and hinged steel armored panels were affixed around the gun mounting that could be folded up for travel or set down to be used as a standing platform for the crew when managing the gun. The gun's mounting allowed for 360-degree traversal but only when the platform walls were either slightly lowered or completely lowered and these walls only offered minimal protection to the crew - a major limitation of the design. Nevertheless, expediency was the call-of-the-day and any aircraft deterrent was better than none. The completed vehicle managed a maximum road speed of 24 miles per hour and an operational range of 120 miles.
The original design as presented to German authorities centered around a 4 x 20mm cannon arrangement. While seemingly impressive, the guns held limited value against Allied aircraft which were becoming faster and reaching greater altitudes to stay out of the range of German guns. Appropriately this design was not followed up on and resulted in a second offering being presented - one with a single 3.7cm (37mm) FlaK 43 series autocannon providing better engagement range, a higher rate-of-fire, and improved penetration value. It was this design that was accepted as the finalized Mobelwagen form and serial production ensued in March of 1944 with 240 units being manufactured into March of 1945.
The 26.5 ton vehicle featured a length of 5.9 meters, a width of 2.9 meters, and a height of 2.7 meters. Armor protection reached 80mm at its thickest but more less just shielded the driver. The 3.7cm cannon was afforded 416 total projectiles which were carried on the vehicle itself and secondary armament - useful in protecting the vehicle from enemy infantry or low-flying aerial threats - was a 7.92mm MG34 machine gun with 600 rounds of ammunition. A leaf spring suspension system offered cross-country travel capabilities.
The Mobelwagen series was quickly pressed into service and results were promising. It was found that the 3.7cm cannon made for an effective ground gun as well and used with equal fervor against light armored vehicles and infantry formations as a fire support weapon when needed (in this role the steel walls needed to be fully in the down position). While initially adopted into German service as an interim solution, the Mobelwagen soldiered on into the war's final days which took place in May of 1945 (European Theater), fighting alongside a collection of other SPAAA vehicles joining the German Army service before the end.