Sheila Widnall

Sheila Marie Evans Widnall (born July 13, 1938) is an American aerospace researcher and Institute Professor Emerita at the Massachusetts Institute of Technology (MIT). She served as the United States Secretary of the Air Force from 1993 to 1997, becoming the first woman to hold that post and the first woman to lead an entire branch of the United States Armed Forces in the Department of Defense. She was elected to the National Academy of Engineering and the American Academy of Arts and Sciences and inducted into the National Women's Hall of Fame.

Sheila Marie Evans was born to Rolland and Genevieve Evans and raised in Tacoma, Washington. She graduated from the Aquinas Academy for Girls in 1956. Encouraged to attend MIT by a local businessman, she graduated from MIT with a SB in 1960, SM in 1961, and ScD in 1964, all in Aeronautics and Astronautics. Her master's thesis was entitled Boundary layer stability over flexible surfaces, and her doctoral thesis was entitled Unsteady loads on hydrofoils including free surface effects and cavitation, both under the supervision of Marten T. Landahl.

After earning her doctorate in 1964, Widnall was hired as the first female faculty member in the MIT School of Engineering, joining the faculty of the Aeronautics and Astronautics Department. She was promoted to Associate Professor in 1970 and to Professor in 1974. She was appointed the Abby Rockefeller Mauzé Professor of Aeronautics and Astronautics in 1986 and joined the Engineering Systems Division. She served as Chair of the Faculty from 1979–1981 (the first woman to hold this position), and as MIT's Associate Provost from 1992–1993. In 1997, when she returned to MIT from her service as Secretary of the Air Force, she was named an Institute Professor. In 2020, she became Professor Emerita after 64 years at MIT.

Widnall's initial research in fluid mechanics was focused on the analysis of vortices trailing from the wings of aircraft. This helped determine the hazards of wake turbulence which was invisible. Her work led to increased safety at airports and improved airport capacity. The Widnall instability is named after her. Her other research included helicopter and aircraft noise, unsteady aerodynamics, wing theory, and turbulent flow.

While at MIT, Widnall was very active in advocating for women students and faculty. She worked with the admissions office to change their procedures for evaluating potential undergraduate and graduate students, mentored students and faculty, influenced the rectification of gender pay inequities, and originated and taught a course for freshmen engineering students to help with retention of women and minority students.

Widnall was a member of the board of investigation into the Space Shuttle Columbia disaster.

Widnall worked with MIT's Lean Aerospace Initiative (LAI) - which investigated the state of the aerospace industry in the United States.^{[citation needed]}

On July 4, 1993, in the wake of the Tailhook scandal, President Bill Clinton announced Widnall's nomination to be Secretary of the Air Force. Prior to her nomination, she had served as chair of the Air Force Academy's Board of Visitors, as well as serving on several Air Force advisory boards. The Senate received her nomination on July 22, 1993, and confirmed her two weeks later on August 5, 1993, 183 days after inauguration and 197 after the office became vacant. She was the first woman to head a branch of the US military. During her tenure, she handled the Kelly Flinn scandal.