Simine explains that the Swiss didn't want to single out a specific sailplane, so chose a stylised version for their 1949 aviation postage stamps

The Swiss Post Office periodically issues a PRO AERO semi-official airmail postage stamp, the proceeds of which are used for the advancement of the Swiss national general aviation. The 1949 issue shows a stylised glider in “symbolised aerodynamic buoyancy”. Date of Issue: April 11, 1949. Country: Switzerland. First Day of Issue Site: Bern. Title: “Pro Aero 1949”. Designer: Hans Erni, SWB Lucerne. As so often, the Post Office did not wish to single out and promote a particular manufacturer or design of a sailplane, so this stamp shows a stylised sailplane which was influenced by contemporary Swiss designs such as the Moswey 2 and the Spallinger S18. The Swiss Pro Aero Foundation was formed in 1938, under the umbrella of the Swiss Aero Club. The sole purpose of this new organisation was promoting and collecting funds to be used for education and training in general aviation, especially of powered flight and sailplanes, but also for model aeroplanes. It is interesting to read that powered flight and model aeroplanes received about the same amount (SFr 243 000) up to 1943, while the gliding received almost a third more (SFr 335 000)! Gliding was originally planned to be part of the 1940 Olympics, but due to the outbreak of World War II it did not happen. The German design Meise, then renamed Olympia, was supposed to be the ship to be used. After peace returned to Europe at the end of the 1940s, the FA. decided to arrange an international gliding competition, independent of the Olympic Games. First England agreed to hold such a meet, but had to drop out. Then Switzerland offered to host the event. The second Internationals were held in Samedan from July 19 to 31, 1948. A Moswey 2 over the mountains near Samaden, site of the 2nd International Gliding Championships in 1948. A S