 In October 1939, while working for the Telefunken electronics firm in Berlin, Hoelzer met with Ernst Steinhoff, Hermann Steuding, and Wernher von Braun regarding guide beams for a flying body.In late 1940 at Peenemünde, Hoelzer was head of the guide beam division (assistant Henry Otto Hirschler), which developed a guide-plane system which alternates a transmitted signal from two antennas a short distance apart, as well as a vacuum tube mixing device () which corrected for momentum that would perturb an object that had been moved back on-track.By the fall of 1941, Hoelzer's "mixing device" was used to provide V-2 rocket rate measurement instead of rate gyros.