Hugh L. Dryden

Date: Born on July 2, 1898, in Pocomoke City, Maryland; died on December 2, 1965, in Washington, D.C.

Definition: American aerodynamicist who conducted pioneering research in high-speed aerodynamics and coined the word “transonic” to mean “at or near the speed of sound.”

Significance: Dryden studied the phenomenon of compressibility associated with fluid motion near the speed of sound and designed wind tunnels to test the aerodynamic problems of transonic flight. His innovative use of a hot-wire anemometer to measure accurately the levels of turbulence in wind tunnels enhanced scientific understanding of turbulence and the boundary layer as they affect flight.

Born in 1898, Hugh Latimer Dryden finished high school at the age of fourteen and received a scholarship to Johns Hopkins University in Baltimore, Maryland. There he studied physics and mathematics and completed his undergraduate work in three years. In 1919, at the age of twenty, Dryden completed his doctorate in applied physics, with a dissertation entitled “Air Forces on Circular Cylinders.”

Dryden then accepted a full-time leadership position in the aerodynamic division of the National Bureau of Standards (NBS). In 1934, he was named chief of the mechanics and sound division. In 1940, he was asked to develop a radar-guided aerodynamic missile head at the Office of Scientific Research and Development (OSRD). He received the Medal of Freedom in 1946 for his work for the U.S. Army Air Force.

After World War II (1939-1945), Dryden was appointed assistant director and then associate director at NBS. He was named the director of aeronautical research of the National Advisory Committee for Aeronautics (NACA) in 1947 and the director in 1949. When the National Aeronautics and Space Administration (NASA) was created after the Soviet Union’s launch of Sputnik 1 in 1957, Dryden became deputy administrator of the new organization, remaining in that position until his death.

The bulk of Dryden’s scientific research was performed prior to his post at OSRD. His ground-breaking research in wind-tunnel design allowed scientists to predict the effects of turbulence on aircraft performance. Using a hot-wire anemometer to measure rapid air fluctuations, he and a colleague found that turbulence could indeed account for the drag on aircraft. Dryden’s wind-tunnel experiments enabled engineers to gain a clearer understanding of laminar and turbulent flows in the boundary layer. Dryden’s work also led him to redesign wind tunnels in order to reduce the effects of turbulence and drag. More efficient wind tunnels led to the design of more effective aircraft. Dryden’s experimental work on the boundary layer and laminar flow validated the earlier theoretical work of Ludwig Prandtl.

In 1938, Dryden became the first American to deliver the Wilbur Wright Lecture sponsored by the Institute of Aeronautical Sciences in England, with an address entitled, “Turbulence and the Boundary Layer.” Dryden received the Daniel Guggenheim Medal in 1950 for his contributions to aeronautics. In 1976, the NASA Flight Research Center in California was renamed the NASA Hugh L. Dryden Flight Research Center. Although Dryden was diagnosed with cancer in 1960, he continued working and lecturing for the next five years before finally succumbing to the disease on December 2, 1965.

Bibliography

Gorn, Michael H. Hugh L. Dryden’s Career in Aviation and Space. Washington, D.C.: NASA History Office, 1996. Valuable information about Dryden’s life and career.

Smith, Richard K. The Hugh L. Dryden Papers, 1898-1965. Baltimore: Milton S. Eisenhower Library, Johns Hopkins University, 1974. A good source of information regarding Dryden’s life and work.

Thomas, Shirley. Men of Space. 8 vols. Philadelphia: Chilton, 1960-1968. A good overview of the U.S. space program, with reference to Dryden’s work.