On 25 February 1927, Charles A. Lindbergh, backed by a group of St. Louis, Missouri, businessmen, contracted the Ryan Airlines Company to build an airplane for the purpose of flying across the Atlantic Ocean from New York to Paris. The agreed price was $10,580. 63 days later, 28 April, Lindbergh made the first flight of the Ryan NYP at Dutch Flats, a short distance from the factory on Juniper Street.
The Ryan NYP is a single-place, single-engine, strut-braced high-wing monoplane with fixed landing gear and tail skid, built at the Ryan Airlines Company factory, San Diego, California. Although it was based on the earlier Ryan M-2, Spirit of St. Louis was a complete redesign, with longer wings and fuselage. The ailerons are smaller. The airplane has no serial number and was not issued a type certificate by the Civil Aeronautics Authority. It was assigned an experimental registration number, NX211.
Spirit of St. Louis is 27 feet, 8 inches (8.433 meters) long with a wingspan of 46 feet, 0 inches (14.021 meters) and height of 9 feet, 10 inches (2.997 meters). The wing has a chord of 7 feet, 0 inches (2.134 meters) and area of 319 square feet (29.636 square meters). There is no dihedral or sweep. The airfoil is the Clark Y, with a cambered upper surface, while the lower surface is flat from aft of the wing’s forward spar.
The fuselage and tail surfaces are constructed of welded tubular SAE 1020 steel framework covered with doped linen fabric. The wing was built as a single unit with wooden spars and ribs. The leading edge is covered in plywood and the entire wing with doped fabric. The rib spacing is 11 inches (27.94 centimeters). The horizontal stabilizer is adjustable from the cockpit to control trim as the fuel load decreased.
The split-axle main landing gear uses bungee cords for shock absorption. B.F. Goodrich pneumatic tires are mounted on 21 inch × 4 inch (533 millimeter × 102 millimeter) wire-spoked wheels. The struts were designed for a load factor of 4 and allow 6½ inches (165 millimeters) of vertical motion. The wheels can spread to absorb impacts. The tail skid is heat-treated chrome moly tubing.
The main fuel tank and lubricating oil tank were placed in front of the cockpit for safety reasons, but this eliminated any forward view for the pilot. A small retractable periscope with a 3 inch × 5 inch (76 × 127 millimeters) viewing area in the instrument panel could be extended through the left side of the fuselage.
Spirit of St. Louis was powered by an air-cooled, normally-aspirated 787.26-cubic-inch-displacement (12.901 liter) Wright Aeronautical Corporation Model J-5C Whirlwind nine-cylinder radial engine, serial number 7331. This was a direct-drive engine with a compression ratio of 5.1:1. The engine was assembled by Thomas W. Rutledge at the Wright factory in Paterson, New Jersey, and was completed 1 April 1927.
The J-5 was built with a cylindrical cast aluminum crankcase and steel cylinder barrels with integral cooling fins. The cylinder head was cast aluminum with a hemispherical combustion chamber, which allowed larger valves and improved combustion efficiency. There were two valves per cylinder, actuated by pushrods and rocker arms.
The Wright J-5C was rated at 200 horsepower at 1,800 r.p.m., and 220 horsepower at 2,000 r.p.m. The engine was 2 feet, 10 inches (0.864 meters) long and 3 feet, 9 inches (1.143 meters) in diameter. It weighed 508 pounds (230.4 kilograms).
During 50-hour endurance tests, the J-5C produced 216 horsepower at 1,837 r.p.m., and 238 horsepower at 1,970 r.p.m. It averaged 223 horsepower during a 100-hour, full-throttle test conducted by the U.S. Navy in May 1927. An overload test run with an external supercharger produced 295 horsepower at 2,150 r.p.m. for 50 hours.
The engine drove a two-bladed Standard Steel Propeller Co. adjustable-pitch propeller with a diameter of 8 feet, 9 inches (2.667 meters). The drop-forged solid Duralumin blades attached to a steel hub. The pitch of the propeller blades could be set prior to flight. Spirit of St. Louis‘ blades were set to 16¼ inches (41.275 centimeters). (This is the distance that the propeller would travel forward during one revolution.)
The airplane’s Instrument panel included a Waltham Watch Company Eight-Day Clock and a Pioneer Instrument Company Earth Inductor Compass.
A barograph was carried on board to certify the non-stop flight for the Fédération Aéronautique Internationale.
During flight testing at San Diego, the maximum speed of Spirit of St. Louis was found to be 120.0 miles per hour (193.1 kilometers per hour) at full load, increasing to 124.5 miles per hour (200.4 kilometers per hour) when lightly loaded. It reached 129 miles per hour (207.6 kilometers per hour) over a 3-kilometer course, when the fuel load was just 25 gallons (95 liters). The Ryan’s best economic speed was 97 miles per hour (156.1 kilometers per hour) at full load, and 67 miles per hour (107.8 kilometers per hour), light. Under ideal conditions, the airplane had a maximum range of 4,110 miles (6,614 kilometers).
Spirit if St. Louis has an empty weight of 2,150 pounds (975 kilograms). When in departed San Diego on 10 May 1927, it was overloaded with an additional 25 gallons (94.6 liters) of gasoline, bringing the total gross weight at takeoff to 5,250 pounds (2,381 kilograms). (The density of California gasoline was 6.12 pounds per gallon/0.73 kilograms per litre.)
Designer Donald A. Hall estimated that the Ryan NYP required 850 engineering man hours and 3,000 construction man hours.
Spirit of St. Louis made 174 flights, with a total duration of 489 hours, 28 minutes. NX211 last made its final flight 30 April 1928, from St. Louis, Missouri, to Bolling Field, Washington, D.C., where Charles A. Lindbergh presented it to the Smithsonian Institution. Its registration was cancelled 2 June 1928.
© 2018, Bryan R. Swopesby