Kaj L. Nielsen was a mathematician, academician, and engineer whose skills were specifically recognized for his contributions to the design and development of two significant aircraft: the Vought F4U Corsair and the Vought V-173/XF5U-1 Flying Pancake (also known as the Flying Flapjack).

The Corsair was a fighter aircraft that first saw service during WWII. Designed as a carrier-based aircraft, it was recognizable by its gull-wing design, which allowed for placement of the landing gear that elevated the aircraft high enough to permit adequate ground clearance for its massive propeller. Kaj Nieslen was one of the individuals who designed the angle in the gull-wing of the F4U.

The Flying Pancake was an experimental proof-of-concept aircraft built for the U.S. Navy’s WWII fighter program. Distinguished by its circular airfoil and “nose-high” attitude, it was designed to take off and land at very low speeds while still being able to perform at high speeds; i.e., to be able to operate from an aircraft carrier. Kaj Nielsen was a member of the design team for the V-173 and focused on the design for the aircraft’s large diameter propellers that rotated in opposite directions.

Born December 3, 1914, in Necker, Denmark, Nielsen immigrated to the United States in 1926 and became a naturalized citizen. In 1943, he married Carlene Z. Weikel, and they had two daughters, Cheryl and Janice.

In 1936, he received a Bachelor of Arts degree from the University of Michigan, a Master of Arts degree from Syracuse University in 1937, and his Doctorate degree from the University of Illinois in 1940. He served as a Carnegie Post Doctorate Fellow at Brown University from 1941-1942.

Nielsen began his professional industrial career as a summer research engineer at Pratt and Whitney Aircraft as well as Woodall Industries during the summers of 1942 and 1943 respectively. In 1944, he joined Chance Vought Aircraft where he served as Analytic Project Engineer until 1945, when he became a mathematician for U.S. Navy ordinance and avionics facilities until 1958. From 1958 through 1961, Nielsen was Chief Operations Analysts and Director, Applied Science Staff for General Motors divisions. He also served at Battelle Memorial Institute as Director, Systems Analysts from 1953-1972.

During his professional years, Kaj also held several academic positions as an instructor, lecturer, and professor at the University of Illinois (1940-1941), Brown University (1941-1942), Louisiana State University (1942-1943), Purdue University (1952-1958), and Butler University (1961-1963 and 1971-1985).

Listed in several directories of academic and professional achievement, Nielsen also held memberships in the American Mathematical Society, Mathematical Association of America, and several fraternities.

Kaj L. Nielsen died February 21, 1972.