This report and its lengthy appendix first reviews early autogyro history. The period from Juan de la Cierva's invention in the early1920s through to the U. S. Army Air Corps' choice, in 1943, of the helicopter instead of the more fully developed autogyro, is examined from a technical point of view. With this historical background in hand, simple aerodynamic technology for rotors, wings, propeller, and fuselages is provided for reference. The McDonnell XV-1 convertiplane development and its program are discussed in detail, with particular emphasis on the wind tunnel and flight testing that was accomplished with two prototype aircraft in the early 1950s. The tip drive rotor system with its ingeniously designed hub was well suited to high speed rotorcraft. The configuration was conceived by Kurt Hohenemser and Fred Dubloff. Many photographs taken of the XV-1 stored at Fort Rucker are included in this report's appendix. Harris, Franklin D. Ames Research Center NASA/CR-2003-212799, A-0310910 NAG2-1597; WU SAT292004D 37895 AUTOGYROS; AERODYNAMICS; FLIGHT TESTS; V/STOL AIRCRAFT; ROTARY WING AIRCRAFT; HELICOPTERS; PROTOTYPES; HISTORIES; INVENTIONS