Hartley A. Soule was born on 19 August 1904 in New York City. He received a bachelor of science degree in mechanical engineering from New York University in 1927 and joined the staff at Langley in October 1927 after working briefly for the Fairchild Airplane Company in Long Island. Soule concentrated his research on stability and control, and became chief of the Stability Research Division in 1943. He became assistant chief of research in 1947 and assistant director of Langley in August 1952.

Soule was a coinventor of the stability wind tunnel and directed the construction of three other wind tunnels at Langley. He pioneered the use of computing machinery for analytical and data reduction. He was also instrumental in establishing the Pilotless Aircraft Research Division at Wallops Island. Soule became chairman of the Interlaboratory Research Airplane Projects Panel, and in that role he directed research on the Bell X-1 program and was instrumental in managing the early years of the X-15 program. Later he became project director for the Mercury worldwide tracking and ground instrumentation system. Soule retired from NASA on 16 February 1962 and passed away in 1988.