Adolf Leopold Steiner (pictured 2nd from the left) was an Aeronautical Engineer who was born in Vienna, Austria in 1903. As a young man, in the early 1920's, Steiner left his Austrian home and resettled in Holland, where he married and raised his family. He worked for the Koolhoven Aircraft Company for which he developed aircraft designs, including the FK 42 (1929), pictured in this photograph. The Rotterdam factory of Koolhoven Aircraft was fully destroyed at the start of World War II by the Nazi Luftwaffe, and was never rebuilt.
Adolf Leopold Steiner went on to a career in the Dutch telecommunications field post WWII. He was granted Dutch citizenship by Queen Juliana of the Netherlands in 1952, and passed away in Holland in 2000.