He was the director at a time when the second generation of imaging systems became operational and began to play a major role in United States intelligence during the Cold War.

[3] Flax participated in the Reserve Officer Training Corps (ROTC) at New York University, but did not receive a commission on graduation.

Within two years he became head of its flutter and vibration group, working on structural and dynamics issues, and on methods for design analysis and testing.

[6][7] In 1944, Flax accepted an offer to join the Piasecki Helicopter Corporation as its head of aerodynamics, structures, and weights—a position normally occupied in a larger company by a senior engineer.

He was part of a small team of engineers who developed the Piasecki HRP Rescuer, the first true tandem rotor helicopter.

[6][7] After the war ended, Flax was offered a position as assistant head of the Aeromechanics Department at the Cornell Aeronautical Laboratory in Buffalo, New York.

Not all of this was related to aeronautics; projects included research into neural networks; the design of automobile safety features such as seat belts and crumple zones; pioneering work; and development of weather radar.

[11] In 1951, he married Ida Leane,[8] who had served as an Army cryptanalyst during World War II, and worked at Piasecki as a mathematician.

In this role he oversaw major growth in NRO funding and personnel, and the production of signals intelligence collectors from space and promoted the development of real-time electro-optical imaging systems for reconnaissance satellites.

It also assisted in coordinating and evaluating technology-based Department of Defense programs like those involved with infrared sensors, new materials, and novel propulsion technologies.