The ski jumping sling system is a training equipment for ski jumpers. It was invented by Spede Pasanen. There was one prototype in the years 1970-1980 in Puijo, Kuopio, Finland. The sling is used to throw ski jumpers from level ground with an acceleration resembling that of a ski-jumping tower. The sling was seen in the film Professori Uuno D.G. Turhapuro.
Spede-Idea Oy still manufactures the sling. The modern version is electronically controlled. The newest sling is designed for the needs of snowboarders for a variety of jumping events. It makes it possible to arrange such events in e.g. city centers.
References
Ski jumping sling Wikipedia(Text) CC BY-SA