Ford Tri-Motor Radial Engine (1925)

A close air-to-air photograph focusing tightly on the thick, corrugated metal wing and the outboard radial engine of a Ford Tri-Motor in flight. — Ford Tri-Motor Radial Engine (1925) · Donald A. Hall Estate Collection

Donald A. Hall Sr. documented contemporary commercial aircraft like the "Tin Goose" to study the rapid evolution of multi-engine metal airframes. As Chief Engineer, Hall meticulously observed the engineering choices of competitors, such as Ford's placement of radial engines on thick monoplane wings.