Museo del Aire, Madrid, Fieseler Fi 156 Storch

Photo: R. Pietracha. Madrid, Fieseler Fi 156 Storch, propeller and the Rupp hub. The propeller had 4 centering holes at the engine’s side and was mounted by single central nut. Fieseler Storch was one of few German aircraft (and probably the last one) utilizing  solution, dating back to WWI times.