The Voyager was designed to become the first aircraft to circumnavigate the globe non-stop without refueling. Three sets of optimized propellers were designed to help increase its range. The first two sets had wooden blades with fiberglass facings. These were abandoned after four failures made their reliability questionable. A third pair of metal propellers was designed, and these were used on the record-setting flight. This paper documents the rationale, theory, and methods used to develop suitable propeller designs for the Voyager. Because of the historical significance of the aircraft, an attempt has been made to include historical details not documented elsewhere.