Mechanical Aileron Pulley System (1927)

A detailed close-up of the exposed wooden wing ribs and the mechanical pulley and wire system used to control the aircraft's ailerons. — Mechanical Aileron Pulley System (1927) · Donald A. Hall Estate Collection

Predating modern fly-by-wire technology by decades, this 1927 photograph documents the mechanical pulley and wire system engineered by Donald A. Hall Sr. to operate the ailerons of the Spirit of St. Louis. The intricate routing of these cables through the wooden wing ribs was essential for Lindbergh's physical flight control.