De Beeler served the National Advisory Committee for Aeronautics (NACA) and the National Aeronautics and Space Administration (NASA) with distinction during a 33-year career as an aeronautical engineer and administrator.
Beeler began his career in aerospace research with the Wright Aeronautical Corporation in the 1930s, and joined the NACA at the Langley Memorial Aeronautical Laboratory in Hampton, Va. in 1941. After several years as a project engineer in Langley's Aircraft Loads division conducting flight research on the XP-51 prototype fighter plane, Beeler transferred to the NACA Muroc Flight Test Unit at Muroc Army Air Base (now Edwards Air Force Base) in December, 1946, joining a small group of engineers and technicians supporting the XS-1 high-speed flight research program being conducted jointly by the Army Air Force, Bell Aircraft Co. and the NACA.
Beeler was the project engineer in charge of the XS-1 aircraft loads program and also served as deputy to Walter Williams, who served as chief of the NACA contingent.
Beeler continued to serve as deputy director as the small contingent of engineers and technicians grew to become, in succession, the NACA Muroc Flight Test Unit in 1947, the NACA High-Speed Flight Research Station in 1949, the NACA High-Speed Flight Station in 1954, the NASA High-Speed Flight Station in 1958, and the NASA Flight Research Center in 1959, now known as the NASA Dryden Flight Research Center.
In addition to serving as the long-time deputy director of the center from 1958 until his retirement in 1974, De also served as chief of the center's Research Division for a number of years, responsible for research planning, design and flight investigations of advanced research aircraft projects. He became Acting Director of the center on April 27, 1971, with former director Paul Bikle serving in an advisory role until Bikle's official retirement on May 31, 1971. Beeler then served as Acting Director until Oct. 11, 1971, when Lee Scherer was appointed Director. Beeler continued as Scherer's deputy until his retirement on Sept. 27, 1974.
Beeler passed away on Sept. 11, 2007 at the age of 92 in Santa Barbara, Calif., where he had made his home since his retirement.