It is known that Nuri Demirağ, who has an important place in Turkish Aviation history, designed, produced and flew many aircraft. We have some information about a significant part of these aircraft. The story of Nu.D.40, the plane that Demirağ took to Germany for aerodynamic tests and remained there when the Second World War started and was forgotten, is not known because the plane was forgotten until this book is prepared by Dr. Emir Öngüner.

Aerospace researcher Dr. Emir Öngüner wrote the story of this plane and published it under the name of “Bir Avcı Tayyaresi Yapmaya Karar Verdim” via TÜBİTAK. Öngüner presents official correspondence, reports, technical drawings and photographs regarding this project, which was tried to be implemented between 1937 and 1939, but never happened.