Blades constructed with wood ribs and are covered with fabric. These blades were used on an early Sikorsky H-5 helicopter. H-5's were used by the U.S. Army Air Corp and the U.S. Navy at the very end of World War 2 and during the early months of the Korean War. Their main uses were for evacuation of wounded and rescuing downed pilots. The H-5 was the forerunner of the Sikorsky H-19.