Drünkler was born on 8 July 1920 in Bernburg, at the time in the Weimar Republic. On 16 May 1942, he was posted to the II. Gruppe (2nd group) of Zerstörergeschwader 2 (ZG 2—2nd Destroyer Wing) operating on the Eastern Front of World War II. There, he flew nine ground attack and was credited with the destruction of an armored train, five locomotives, two freight cars and five trucks. Predominately however, he was tasked with making courier flights. On 1 October 1942, Drünkler transferred to the 2. Staffel (2nd squadron) of Nachtjagdgeschwader 5 (NJG 5—5th Night Fighter Wing) where he was trained as a night fighter pilot.
