Dated 1928. By Airship to Ophir, written by Fenton Ash, tells the story of an airship and two aircraft meander round central Africa picking up an assortment of natives in a search for the fabled land of Ophir, which is eventually reached and found to be inhabited by a race of people of Arab/Hebrew mien.
Fenton Ash is the first and main pseudonym of UK civil engineer and author Francis Henry Atkins (1847-1927) who was a writer of pulp fiction, in particular science fiction aimed at younger readers.