Flew the California Arrow, the first first successful dirigible in America powered by an engine, at the Louisiana Purchase Exposition of St. Louis, competing against all domestic and European dirigibles, and won the Grand Prize for his performance.
Raced an automobile from Los Angeles to Pasadena, California in the California Arrow and won.
Started to build his own dirigibles which he flew at state fairs and also engaged in promoting public exhibitions. In August 1905 he flew his 69 foot long Toledo II airship at Central Park in New York City, stopping all business and street traffic. Knabenshue’s third dirigible was completed and flown in exhibitions at Hartford, Connecticut, Providence, Rhode Island, Worcester, Massachusetts and London, Ontario in 1907.
Began to build a three-man airship in 1907 designed to carry passengers as well as for exhibition work. In May 1908 Roy made an ascent at Toledo in this airship with two others aboard.
Participated in the First International Air Meet at Dominques Field, Los Angeles, racing his dirigible against others.
Employed by the Wright Brothers to plan exhibitions. Knabenshue arranged for the team to perform in Atlantic City, along the Chicago LakeFront, and in the Belmont Park International Air Meet.
Started a dirigible passenger flight service in 1912 in Pasadena, California.
His blimp, White City, made history in 1913 and 1914 with aerial sightseeing over the Midwest.
During World War I, he built observation balloons for the Government and, later, he worked for the National Park Service and an aircraft instrument repair organization.