 Osterkamp joined the new "Luftwaffe" on August 1, 1933 with the rank of "Hauptmann".He also participated in the second, third and fourth FAI International Tourist Plane Contest Challenge 1930 (11th place), Challenge 1932 (12th place) and Challenge 1934 (5th place).By the time the war broke out in September 1939 he was a "Oberstleutnant" in command of the "Jagdfliegerschule 1" (JF1).