Flakpanzer IV Wirbelwind (Whirlwind) Wirbelwind was one of the successors of Flakpanzer IV Möbelwagen armed with the 37 mm Flak 43 L/89. In May 1944, the first prototype of Wirbelwind (Whirlwind) using the chassis of Panzer IV was produced. This conversion was to be carried out starting from PzKpfw IV (Panzer IV) damaged and returned from the front (mainly Ausf.F/G). The concept of Wirbelwind comes from Karl Wilhelm Krause, an officer of 12th SS-Panzer Division &quot;Hitler Jugend&quot;