...resulted in the deletion of the radiator and associated plumbing that was always a source of maintenance and reliability problems on liquid-cooled engines. The maximum gross weight of the aircraft was 5135 pounds, and the zero-fuel weight was 2150 pounds. Thus, the fuel in the aircraft represented more than half of the gross weight and gave the Spirit of St. Louis airplane a zero-wind range of about 4200 statute miles. The cruising speed of the aircraft was about 95 miles per hour, and the maximum speed, 120 miles per hour. The zero-lift drag coefficient CD,0, given in table II (appendix A), was 0.0379. This coefficient represents a considerable reduction over the value of 0.0496 given for the DeHavilland DH-4 but still indicates that the fixed landing gear and multiple wing struts were serious drag-producing elements. The maximum lift-drag ratio of the aircraft was 10.1, which compares favorably with the value of 7.7 given for the DeHavilland 4. The higher effective aspect ratio of the monoplane, compared with the biplane, is in large measure responsible for the increased lift-drag ratio of the Spirit of St. Louis compared with the DH-4 and other typical contemporary biplane configurations. A complete description of the Spirit of St. Louis giving design and performance data is contained in the appendix of reference 86.