John T. Parsons

John T. Parsons (1913 to 2007) was an American manufacturing engineer who pioneered numerical control for machine tools in the 1940s. Working with his chief engineer Frank L. Stulen, whom he hired at Wright-Patterson Air Force Base in 1946, he was among the first to use computer methods, then punched-card calculating machines, to solve machining problems, notably the accurate interpolation of the curves that describe helicopter rotor blades. In 1948 his firm, Parsons Corporation of Traverse City, Michigan, won a contract for tapered military aircraft wings because it could compute the difficult three-dimensional shapes, with IBM and MIT as subcontractors. MIT later developed servo control and the APT programming language for numerical control machines. Parsons saw early that computers could be connected to machine motors, and he received a patent for a motor controlled apparatus for positioning machine tools in 1958. The development costs were so high that he was removed from his own company, and reinstated only after patent royalties, with Bendix an early licensee, paid off. He and Stulen received the National Medal of Technology in 1985, and he was inducted into the National Inventors Hall of Fame in 1993.