Maj. Rudolph W. Schroeder set world altitude record of to 28,500 feet, setting a two-man altitude record with Lt. George A. Elfrey as passenger at Mc Cook Field, Ohio. Continuing the test, Schroeder and Elfrey went to 30,900 feet on September 24 and to 31,821 feet on October 4th 1920
United States Air Force
Maurer Maurer, 1987, Aviation in the US. Army, 1919-1938, United States Air Force Historical Research Center, Office of Air Force History,  United States Air Force, Washington, D.C.