Friz designed the first practical German aircraft engines in 1912-1913 while at Austro-Daimler. The engines had separate cylinders on the crankcase and an overhead camshaft driven by a vertical shaft and bevel gears. At the end of 1916 the young engineer Max Friz applied for a position with Rapp Motorenwerke. At that time Friz was still working for the Daimler engine company in Untertürkheim, near Stuttgart. However, he was frustrated because the chief engineer, Paul Daimler, ignored the suggestions of his young assistant on engine development. Faced with this situation, Friz remembered his former colleague, Karl Rapp. At first Rapp was going to turn down Friz’s request; however, Josef Popp successfully intervened on Friz’s behalf, because he recognized that Rapp Motorenwerke lacked an able designer.