Otto C. Koppen (1901 – 1991) was an American aircraft engineer.

Otto Koppen graduated with a Bachelor of Science from MIT in 1924.

Koppen was the professor emeritus of aeronautical engineering at the Massachusetts Institute of Technology. In 1929 Koppen returned to teach stability and control at MIT, where he remained until his retirement in 1965. As part of the course, Koppen took students up in a Fairchild 24 to demonstrate stability principles.

In 1936, Koppen published a paper called "SMART AIRPLANES FOR DUMB PILOTS".

In 1939, a student brought a model of the new Curtiss XSB2C-1 to the MIT wind tunnel. Koppen was quoted as saying, "if they build more than one of these, they are crazy". He was referencing controlability issues with the small vertical tail. The eventual production aircraft did have issues, and needed over 880 modifications before entering combat in WWII.

In 1944 America recognized a need for a universal flight trainer more advanced than the analog Link Trainer. What started as the development of the Aircraft Stability and Control Analyzer (ASCA) for the Navy became "Project Whirlwind". Headed by Captain Luis deFlorez, Otto Koppen, John R. Markham, and Joseph Bicknell put together the requirements for a simulator that factored in winds and aerodynamic forces. The byproduct that was developed to compute the data was one of America's first high-speed, prototypical, digital computer.

Koppen took a two-year break from teaching after the loss of his daughter in a flight accident involving loss of control in low visibility conditions. Koppen promised his wife never to fly again afterward, but restarted after her death. Koppen flew a Grumman Yankee and experimented with wing-leveling and other controls. Koppen acquired his FAA instrument rating at the age of eighty. At one point Koppen was the oldest instrument rated pilot in America.

Koppen is regarded as providing the basis for most stability and control research since the 1930s.