Radar

In 1934 Irving Wolff '16, who already held 80 patents (on sound systems for movie theaters, among other things), teamed up with another scientist from RCA to build the world's first radar set. A few years later Wolff packed a portable version into a Ford Trimotor plane and demonstrated radar's usefulness as a navigational aid.

Wolff co-invented radar and then got it off the ground.