En attendant une réponse de Sup’air j’ai retrouvé ça (extrait d’un article paru dans une revue ricaine) :
"The second popular type of protector is the foam airbag. I have been fortunate in that Helmut Hinter, the inventor of the foam airbag, has been very supportive and helpful, sharing ideas and information with me over the years, so I can speak with some authority on the topic. Most pilots mistakenly assume it’s the foam that imparts the impact absorption. In fact the primary role of the foam is simply to hold the airbag open and support the partition walls to prevent buckling. Helmut developed the multi-chambered (five) foam airbag (Bumpair) now in common usage. With five chambers and partitions supported by foam, his 20 cm airbag was significantly more effective than a 30 cm ram airbag. Recently Helmut has worked on improving the design further by developing a foam airbag with rounded, rather than straight, partitions such the walls do not distort at all on impact for even greater efficiency. While his tests show the design to be considerably more effective than his earlier designs, manufacturers have been slow to adopt the concept. "
Sur le dernier point apparament ça a finalement été adopté au moins par Supair (cf leur site “Profil arrondi des parois pour un meilleur amortissement.”)
Charly Produckte avait une protection qui fonctionnait comme vous le décrivez (Charly Scooter), 20 cm de mousse, rigide comme du polystyrène, pas vraiment pratique.
