European airmail exhibition "Lilienthal '91" - Germany / German Democratic Republic 1990 - 20 Pfennig

Historical model aircrafts On the occasion of the European airmail exhibition "Lilienthal '91" the Ministry for post office and telecommunications of the GDR gives out four multicolored special postage stamps, one of them with surcharge, with the pictures of historical model airplanes. Special Cancellation from February 20 to April 19, 1990 Historic Model Airplanes 20 Pfennig Value: Leonardo da Vinci 1452-1519 Leonardo da Vinci is one of the most important pioneers in aviation technology. He was deeply convinced of the realization of the human flight and the flight was the problem that moved him most deeply throughout his life. For security reasons, he kept his manuscripts hidden. The heirs of his estate left these treasures unnoticed for centuries. Only when Napoleon invaded northern Italy in 1796 and carried off the valuable documents as war booty did the publication of the estate begin. Leonardo carefully examined the physique of the birds. He was particularly interested in the control maneuvers, where he was the first to discover the basic elements of flight stability, the "center of gravity" and the "center of resistance." The right balance between the two points determines the equilibrium of the flight, as Leonardo recognized in his bird studies Vinci the gliding of the birds, which could have led to a departure from the swinging flight and turning to the practical gliding flight.