Complex sentence: Three-bladed metal propellers were used, with duralumin blades and steel hubs, with a diameter of 3.4-3.5 m (11.2-11.5 ft).
Split into simpler sentences: Three-bladed metal propellers were used with duralumin blades and steel hubs. They had a diameter of 3.4-3.5 m (11.2-11.5 ft).