propeller-detail-drawingpropeller-detailOLYMPUS DIGITAL CAMERAThe airship manufacturer Augustus von Parseval (1861-1942) used non-rigid propellers for his first airships, which consisted principally of cloth. It was only in operation, which means, by means of the fast rotation, that they obtained form and stability. A corresponding patent ‘Unstable air screw with fly weights’ was issued in 1908.