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The concept of underwater wings, which allowed to reach a dramatic increase in the speed of ships and to create a fastest US NAVY ship, was proposed back in the XIX century. Since then, this design, embodied in thousands of ships, has come a long way and is now widely used in shipbuilding.
The essence of the concept of US NAVY hydrofoils is to lift the hull of the vessel from the water and maintain it in this position in a dynamic mode, using for this purpose the planes, which are commonly called submarine wings. As a result, with Pegasus class ship it is possible to reduce the influence of waves and reduce energy consumption when driving at high speed on this fastest ship in the NAVY, often unattainable in the conventional (water displacement) mode. For NAVY hydrofoil boat with fully submerged wings, which almost completely insulate the ship’s hull from the influence of waves but trigger the lack of self-stabilization, an “autopilot” is needed to track the position of the fastest ship in US NAVY and correct the lift of the wings by changing the angle of attack and deflecting the flaps.
The role of Western Europe in creation of the Pegasus class hydrofoils
Western Europe also did not stand aside. Gustoverft in Holland, Westermoen in Norway, Vosper Thornycroft in the UK are actively engaged in the development and construction of hydrofoils. But the most successful commercial projects developed and built in Western Europe are, of course, the works of the Italian Rodriquez Centieri Navali. Among many of its products, it would be worth noting the series of commercial vessels RHS. Over the years, vessels of this series grew in size and ventured out into those waters where their wings, in principle designed to slip over the surface, were subjected to such loads, which cannot be found in rivers, lakes, and coastal lagoons. To create an acceptable environment for passengers, Rodriquez has developed a “Seakeeping Augmentation System” (SAS), which, as practice has shown, is very successful in combating vertical, pitching, and rolling with very strong excitement.
Boeing Jetfoil had a water jet propulsion, fully submerged wings, a cruising speed of 45 knots at a fairly high wave and at the same time provided decent comfort for passengers.
In the early 1950s, the New York shipbuilding firm Gibbs & Cox joined forces with a group of specialists from the US Navy to create a universal experimental hydrofoil vessel. The device was built by Bath Iron Works and named BIW. It was a boat 6 m long, 1.5 meters wide and 0.8-ton displacement, with a 22-hp outboard motor. BIW was very useful for testing various assemblies of underwater wings, control systems, various sensors. The most important result of this work was the basis for the development of electro hydraulic autopilot, as well as the decision to build a new vessel of this series – SEA LEGS (“Sailor’s Walk”). An electronic autopilot containing 160 radio tubes was developed by Draper Laboratory in collaboration with the Massachusetts Institute of Technology. In 1957, SEA LEGS made the first voyage, demonstrating excellent seaworthiness in high waves at speeds up to 27 knots.
This success inspired the shipbuilders and the American NAVY seriously engage in the experimental apparatus on hydrofoils.