Frank L. Stulen

While working at Parsons Corporation, he invented numerical control of machine tools in collaboration with Parsons. Though Parsons developed many of the core ideas, it was Stulen, as chief engineer, who turned these ideas into working machines and processes. In 1985, Stulen and Parsons were jointly awarded the National Medal of Technology by President Ronald Reagan for "Revolutioniz[ing] Production Of Cars And Airplanes With Numerical Controls For Machines".

Stulen was also Mayor of Traverse City, Michigan in 1961 and 1962.

That development led Parsons to consider the possibility of using stamped metal stringers instead of wood. These would not only be much stronger, but far easier to make as well, as they would eliminate the complex layup and glue and screw fastening on the wood. Duplicating this in a metal punch would require the wooden jig to be replaced by a metal cutting tool made of tool steel. Such a device would not be easy to produce given the complex outline. Looking for ideas, Parsons visited Wright Field to see Stulen, the head of the Propeller Lab Rotary Wing Branch. During their conversation, Stulen concluded that Parsons didn't really know what he was talking about. Parsons realized Stulen had reached this conclusion, and hired him on the spot. Stulen started work on 1 April 1946 and hired three new engineers to join him.

In 1942, Parsons was told that helicopters were going to be the "next big thing" by the former head of Ford Trimotor production, Bill Stout. He called Sikorsky Aircraft to inquire about possible work, and soon got a contract to build the wooden stringers in the rotor blades. At the time, rotor blades were built in the same fashion that fixed wings were, consisting of a long tubular steel spar with stringers (or more accurately ribs) set on them to provide the aerodynamic shape that was then covered with a stressed skin. The stringers for the rotors were built from a design provided by Sikorsky, which was sent to Parsons as a series of 17 points defining the outline. Parsons then had to "fill in" the dots with a French curve to generate an outline. A wooden jig was built up to form the outside of the outline, and the pieces of wood forming the stringer were placed under pressure against the inside of the jig so they formed the proper curve. A series of trusswork members were then assembled inside this outline to provide strength.

Frank Lem Stulen (January 22, 1921 – June 25, 2010) graduated from Carnegie Mellon University (then Carnegie Tech) in 1942 with a degree in aeronautical engineering. After graduation, Stulen served in the U.S. Army Corps of Engineers and in the U.S. Air Force from 1942 to 1946, where he was head of the Propeller Lab, Rotary Wing Branch based out of Wright-Patterson Air Force Base. After a meeting with John T. Parsons, he was hired as Chief Engineer and Vice President of Engineering at Parsons Corporation in Traverse City.

Stulen was born on January 22, 1921 in Pittsburgh, Pennsylvania. He went to Carnegie Mellon University (then called Carnegie Tech), and moved to Traverse City, Michigan to begin his work with Parsons.