Also known as the Davis-Douglas Cloudster, this was the first Douglas aircraft, built in 1921 for a transcontinental flight which was aborted. In 1923 it was modified for sightseeing flights. In 1925 it was sold to Ryan Airlines and modified further into a plush airliner by American standards - there were no passenger airlines then in the USA. Their LA - San Diego service was unsuccessful and the aircraft was apparently used for smuggling booze when it crashed in Mexico in December 1926. Photo from: San Diego Air & Space Museum