Photograph of a Douglas C-1 aircraft (fuselage number 1) aerially refueling the "Question Mark," a U.S. Army Air Service Fokker C-2A aircraft, circa 1929.
Photograph of a Douglas C-1 aircraft (fuselage number 1) aerially refueling the "Question Mark," a U.S. Army Air Service Fokker C-2A aircraft, circa 1929.