Despite the fact that D.D. Arnold has a biographical file at the Smithsonian (cited, left sidebar), the content of the folder consists of a single entry from the book Who's Who in American Aeronautics from 1928. According to that entry, Arnold was born in May (23rd?), 1899. He was one of seven children. Web-based findings state he was born in 1898 on that day. According to the Arlington National Cemetery, he died on January 1, 1946.

Piecing together various clues, it appears he had a son born ca. 1927 who was killed during the Korean War, just a few years after Arnold, Sr's. passing. I understand, too, that he has a grandson whom I tried to email but the address is out of date. If you know his grandson, please direct him to this page and the link to me in the right sidebar.
D.D. Arnold and Veronica Lake, Life Magazine, 1941 (Source: Woodling) D.D. Arnold and Veronica Lake, Life Magazine, 1941 (Source: Woodling)

Beyond these basic facts, he is cited in the Who's Who as being a flying cadet (soloed during 1915 at Buffalo, NY) and participating in ground school at Cornell University and Ellilngton Field from 1917-1918. During 1920-21 he was in flight instruction at Carlstrom Field. In 1921 he acted as a pilot and bombardier in bombing tests conducted in Chesapeake Bay on the U.S.S. Alabama, Indiana, San Marcos and the German vessels Ostfriesland and Frankfort. In that task he was in league with fellow Register pilot Dutch Shankle.

Further, he participated in the development of the municipal airport for the City of Buffalo, NY and served as Lieutenant of Aerial Police for the City. As of 1928, he was on active duty serving as 1st lieutenant at Maxwell Field, Montgomery, AL.

Even his entry in the Register is slim. He landed at Tucson once on Friday, May 29, 1931 at noon. He did not list the type or registration number of the airplane he flew. He appeared to be in a flight of two with fellow Army pilot H.C. Lichtenberger flying in 28-362, a Consolidated PT-3. Both were solo. Although both signed their arrival date and time, neither left departure information. They were based at San Antonio, TX Brooks Field, and they were eastbound from Yuma, AZ back to Brooks.

Ten years later, Arnold posed with film star Veronica Lake for Life Magazine, right. About that time Lake starred in the 1941 film "I Wanted Wings," which was filmed with Army cooperation at Randolph Field in San Antonio, TX. Incidentally, Lake learned to fly in 1946