Van der Wall, an aerospace engineer, offers a transcription and translation of Göttinger Monograph N, which summarizes the research results obtained from 1939 to 1945 on the development of the German helicopter and autogyro. It describes aircraft like the Fw-61, Fa-223, Fa-230, Fl-339, and areas like the design of rotors, testing and accidents, Glauert-Lock-Wheatley's rotary-wing theory, dynamic rotor problems, performance investigations, flying qualities, ground effects, a helicopter with flapping propulsion, a jet-powered helicopter, and the helicopter as takeoff assistance for a normal aircraft. Appendices detail modifications to the original manuscript, the origins of the monograph, and individuals involved, such as Henrich Focke, Anton Flettner, Friedrich von Doblhoff. Annotation ©2016 Ringgold, Inc., Portland, OR (protoview.com)