The limitations of the earlier quad-20mm-armed, Panzer IV tank-based "Wirbelwind" Self-Propelled Anti-Aircraft Gun (SPAAG) system led to the development of, yet another, Panzer IV-based form in the Flakpanzer IV "Ostwind" ("East Wind"). This version reverted to a single 37mm autocannon (similar to the earlier "Mobelwagen") though with an all-new, six-sided, open-air turret. The crew remained five (driver, commander/gunner, radioman and two loaders) while all other automotive aspects of the Panzer IV tank were retained including its Maybach 296 horsepower gasoline engine.
Development of the Ostwind began in earnest during 1944 and was intended as a direct replacement for the limited-value Wirbelwind line. The Ostwind brought about improved capabilities, primarily through its more powerful gun which could reach farther with better penetration value than the preceding 20mm types of the Wirbelwind. The turret was simpler in its design which aided construction and added better protection for the partially exposed gunnery crew. The 12-cylinder engine coupled with a leaf-spring suspension system allowed for serviceable cross-country travel and speeds on roads reached 24 miles per hour with operational ranges out to 120 miles.
The 3.7cm FlaK 43 L/89 autocannon was centrally fixed in the traversing turret with its gunnery crew manning the particular aspects of direction, gun laying and ammunition loading. 1,000 x 37mm projectiles were carried aboard and loaded through cartridges by the dedicated ammunition handlers. A single 7.92mm MG34 machine gun was retained for point self-defense duty of the vehicle, primarily to defend it from oncoming enemy infantry. When not engaging low-flying aerial targets, the 37mm main gun could be brought to bear, with surprising success, against light-armored vehicles and infantry as required - making the Ostwind something of a dual-role battlefield presence.
In August of 1944, the German Army commissioned for 100 Ostwinds in an ever-growing desperate situation. As with the Wirbelwind before it, the concern of Ostbauwerke would be charged with manufacture of the SPAAG and this from the period spanning December of 1944 to March of the following year. However, only some thirty-seven vehicles emerged from existing Panzer IV stocks and a further seven "new-build" vehicles were added - the 100-strong agreement would never be reached amidst the collapsing German war industry.
To that end, the war in Europe was over in May of 1945 and this saw Ostwinds serve as best they could until the conclusion of the conflict.