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Frank Walker Caldwell (1889–1974) was a leading American propeller engineer and designer. As the United States government’s chief propeller engineer (1917–1928), he pioneered propeller engineering and propeller testing facilities and techniques. Working at Hamilton Standard Propeller Corporation, they won the 1933 Collier Trophy for his work on the controllable-pitch propeller.[1] After 25 years of service, he retired in 1955 as director of the United Aircraft Corporation Research Division.[3]
. . . Frank W. Caldwell . . .
Caldwell was born in Lookout Mountain, Tennessee, to Frank Hollis Caldwell and Mary Ellis Nellie Walker.[2] His father was president of the Cahill Iron Works and mayor of Chattanooga.[4] He attended the Tome Preparatory School in northeast Maryland and the University of Virginia.[4][5] In 1912, he graduated from the Massachusetts Institute of Technology with a Bachelor of Science degree in mechanical engineering.[3] While at MIT, Caldwell and fellow student Hans Frank Lehmann designed a contest winning glider.[4] At that time, MIT did not offer courses in aeronautics, yet working with Hans Lehmann, Caldwell titled his graduate thesis “Investigation of Air Propellers.”[4][5] After graduation, he worked as foreman and process engineer at Curtiss Aeroplane and Motor Company in Buffalo, New York. In 1916, Caldwell traveled to investigate Army airplane propeller de-lamination at Columbus, New Mexico, near the Mexican border. Realizing that propellers glued in New York delaminated in the southwest heat, he developed a new glue that improved propeller reliability.[5]
During World War I, Caldwell became the chief engineer in the Propeller Research Department of the Airplane Design Section, Aviation Section of the Signal Corps based at McCook Field (1918-1927).[6] While at McCook and Wright Field (1926-1938) he was responsible for all aircraft propeller development.[3] In Ohio, Caldwell designed the whirl test by mounting the subject propeller on a fixed stand to measure thrust, endurance, speed, efficiency, and structural strength.[3] Post war propeller design moved from wood to metal and fixed pitch to variable pitch. Caldwell pushed propeller development to individual detachable blades joined to a central hub allowing, on the ground, pre-flight adjustment of the blades to satisfy performance goals:[3] fine pitch for best climb or coarse pitch for improved cruise performance.[7]Charles A. Lindbergh‘s 1927 solo transatlantic aircraft the Spirit of St. Louis used a ground only adjustable pitch propeller made by Standard Steel Propeller Company.[3]
. . . Frank W. Caldwell . . .