National Geographic : 1924 Jul
Official Photograph, U.S.Army Air Service MCCOOK FIELD, NEAR DAYTON, OHIO, IS THE AVIATOR'S LABORATORY At this test field of the Engineering Division, U. S . Army Air Service, new devices are tried out. Notable among the experiments now inprogress are those with the helicopters. New airplanes are tested out here before being put into the service. Dayton was the starting point for the Stevens Macready photographic expedition (see page 85).