Irmgard Flügge-Lotz

Irmgard Flügge-Lotz, née Lotz (16 July 1903 – 22 May 1974) was a German-American mathematician and aerospace engineer. She was a pioneer in the development of the theory of discontinuous automatic control, which has found wide application in hysteresis control systems; such applications include guidance systems, electronics, fire-control systems, and temperature regulation.

Early life and education Lotz was born in Hamelin, Germany on 16 July 1903. She was encouraged at an early age to pursue technical subjects by her mother, whose family had been involved in construction for several generations. She often visited construction sites with her uncle and attended half-price matinee shows for technical films. After her father, Osark, a travelling journalist, was drafted for military service in World War I, the young Irmgard helped the family by becoming a math tutor while studying at a girls' Gymnasium in Hanover. Several years later, when Osark returned to Hanover he was in poor health and Irmgard continued to work to bring in extra money for the family. She graduated from the Gymnasium in 1923 and entered the Leibniz University Hannover to study mathematics and engineering. Later in life, she explained why she decided to study engineering:

In college she studied applied mathematics and fluid dynamics and was often the only woman in her classes. Following this achievement, she was promoted to team leader and built the theoretical department at the AVA by establishing her own research program and assisting other research groups.

At DVL Flügge-Lotz began her career in automatic control theory and pioneered the theory of discontinuous control systems. She was mainly interested in the implications these systems had for the development of simple automatic flight control equipment. However, the theory describing their performance needed to be developed before they could be reliably implemented in physical systems. Flügge-Lotz began developing the theory while at DVL, but wartime priorities limited her time for heavily theoretical projects so she focused mainly on aerodynamics during this time. After the end of the war, Saulgau was in the French zone of Allied-occupied Germany. The French relaunched their aeronautical research activity and were eager to hire German scientists, so in 1947 Flügge-Lotz and Flügge moved with many of their colleagues to Paris to join the Office National d'Etudes et de Recherches Aerospatiales (ONERA). Flügge-Lotz served as Chief of a research group in aerodynamics until 1948 and published papers in both automatic control theory and aerodynamics, in which she discussed the problems arising from the increased speed of aircraft.

Awards and organizations During her lifetime, Flügge-Lotz received many honors for her work. In 1970, she was elected a Fellow (first woman) of the American Institute of Aeronautics and Astronautics (AIAA) and chosen to give the von Kármán lecture to the AIAA in 1971. She received the Achievement Award from the Society of Women Engineers in 1970 “For her significant contributions to the field of fluid mechanics, in particular wing theory and boundary layer theory. Notably: Computation of wing-life distributions.” She received an honorary doctorate from the University of Maryland in 1973. The citation for her honorary degree stated:

Professor Flügge-Lotz has acted in a central role in the development of the aircraft industry in the Western world. Her contributions have spanned a lifetime during which she demonstrate, in a field dominated by men, the value and quality of a woman's intuitive approach in searching for and discovering solutions to complex engineering problems. Her work manifested unusual personal dedication and native intelligence.

In honor of her contributions, the “Wilhelm Flügge and Irmgard Flügge-Lotz Memorial Award" was established by the Applied Mechanics Division at Stanford University for outstanding graduate students. Discontinuous and Optimal Control, McGraw Hill 1968