Navy Achieves New Propeller Milestone

The U.S. Navy has marked a critical milestone in ship research as it wrapped up a successful phase in the testing of a full-scale propeller for USS San Antonio amphibious transport dock ship. The tests verify a new compact design for the LPD-17 controllable pitch propeller meets the seven-year service life cycle requirements. The 17 million cycles completed show this new design exceeds requirements and the service life could be extended twofold. The Naval Sea Systems Command program could lead to a significant saving for the Navy in overhaul costs for the new propeller. The hub and blades, manufactured of nickel-aluminum-bronze and steel, constitute a unique design. The hub has a smaller diameter than in the past, leaving less surface for attaching the five blades and increasing stress in the blade root area and the hub. Verifying the new design will facilitate extending the period between overhauls from 7 to 14 years, producing lower costs, easier maintenance and faster upgrades Carderock propeller experts working with the Bird-Johnson Company, the hub designer and prop fabricator, designed the blades. Small scale prop models were then tested in another unique Carderock facility, the Large Cavitation Channel, in Memphis. There, scaled props were mounted on ship model hulls where the flow of water over the hull and around the prop is the same as a real vessel at sea.