On 16 January 1931, Ernst Heinkel recruited Siegfried Günter to work for his Heinkel company in Rostock, and Walter joined the company on 31 July 1931, where he was in charge of developing low and high-speed wind tunnels.[1][3] There they were to design some of the most important and famous designs associated with the company, including the Heinkel He 51, He 70, He 112, He 100, and the He 111. Walter designed the first ever retractable landing gear in Germany for the He 70, an aircraft mainly designed by Siegfried.[2]