hydrofoil

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hydrofoil,

flat or curved finlike device, attached by struts to the hull of a watercraft, that lifts the moving watercraft above the water's surface. The term is often extended to include the vessel itself. Like an aircraft wing in its appearance and function, the foil develops lift as it passes through the water; the hull is raised above the surface, and the drag caused by the vessel's contact with the water is thereby reduced. Hydrofoil vessels are capable of traveling faster than 70 mi (113 km) per hr. They are used for ferries in many countries in Europe and Asia; in the United States they are used mostly for military purposes. In addition to offering greater speeds, such vessels do not pitch and roll as do conventional watercraft. Foils may be of the submerged or the surface-piercing type. On oceangoing passenger ships a type of hydrofoil called a stabilizer is used to minimize wave action on the vessel. The first hydrofoil vessel was built in 1905 by the Italian engineer Enrico Forlanini. In 1918, Alexander Graham Bell built the HD-4, a vessel 60 ft (18.3 m) long that attained a speed of 70.86 mi (114.03 km) per hr.

Bibliography

See C. Hook, Hydrofoils (1967); R. McLeary, Jane's Surface Skimmers (annually, 1968–); W. T. Gunston, Hydrofoils and Hovercraft (1969).

Hydrofoil

 

a ship constructed with submerged winglike devices (foils) that generate lift during forward motion, raising the vessel’s hull above the level of the water. A patent for a hydrofoil was awarded in Russia in 1891, but such vessels were not placed in service until the second half of the 20th century. The theory of hydrofoil transport was formulated by the Soviet scientists M. V. Keldysh, M. A. Lavrent’ev, N. E. Kochin, and A. I. Vladimirov, among others.

When not in motion, a hydrofoil is supported by buoyancy in its water-displacing position. When the vessel reaches a certain velocity, the hull rises above the level of the water. As the area of the hull in contact with the water decreases, only the foils, struts, rudders, propeller shafts, and propellers remain immersed, and the resistance of the water to forward motion is reduced. Hydrofoils attain higher speeds for a given specific fuel consumption than either conventional displacement craft or hydroplanes. Hydrofoils are stabilized after takeoff by the automatic varying of the immersion area or depth of fixed foils or by varying the attack angle of adjustable foils; these same techniques are used to ensure longitudinal and transverse stability.

Hydrofoils with fixed foils that are shallowly submerged and that do not intersect the surface of the water are used primarily on rivers; arched or V-shaped surface-piercing foils that run deeply submerged are more suitable for turbulent waters. Adjustable foils are increasingly used for seagoing hydrofoils. These vessels are equipped with a device that tracks the shape of oncoming waves so that the attack angle of the foils may be controlled.

Hydrofoils are used to transport passengers and small express cargoes. In the military they serve as torpedo boats and rocket carriers; other official functions include service as guard and dispatch boats.

Hydrofoil hulls are usually constructed of light alloys, and stainless steel is used for the foils. The power plants are internalcombustion engines or gas turbines, and propellers are used for propulsion. Hydrofoils are capable of speeds of 80–100 km/hr and more. Passenger hydrofoils are usually equipped with airplane-type seats.

The first Soviet Raketa-type hydrofoil, which was built in the USSR in 1957, had 66 seats. In 1976, the shipbuilding industry of the USSR manufactured both river-service and seagoing hydrofoils that accommodated 150 to 250 passengers.

REFERENCES

Murugov, V. S., and O. V. Iaremenko. Morskie suda na podvodnykh kryl’iakh. Moscow, 1962.
Zaitsev, N. A., and A. I. Maskalik. Otechestvennye suda na podvodnykh kryl’iakh, 2nd ed. Leningrad, 1967.

E. G. LOGVINOVICH

hydrofoil

[′hī·drə‚fȯil]
(naval architecture)
A flat or airfoil-shaped plate attached to a ship to stabilize it in roll.
Foils attached by struts to the bottom of a hydrofoil boat to lift the hull out of the water as its speed is increased.

hydrofoil

a fast light vessel the hull of which is raised out of the water on one or more pairs of fixed vanes
References in periodicals archive ?
Uhlman, "The surface singularity or boundary integral method applied to supercavitating hydrofoils," Journal of Ship Research, vol.
One illustration in the book described a plan for a boat he called the Merrimac: an idealization of his concepts featuring three hydrofoils, a wing-like airfoil instead of a sail, and a cockpit hoisted clear out of the water.
One concept, the well-known hydrofoil, behaves like an aircraft wing to lift a hull out of the water.
One look at any image of an America's Cup boat at full throttle and it doesn't take much to work out that one of the most highly loaded components is the hydrofoil boosting the boat out of the water.
To calculate the reduction gearbox of the vehicle, responsible for the transmission between the rotational force of the propeller, and the translational force of hydrofoils, it was necessary to assess which factors influence the behavior of the vehicle.
The objective of this effort is to develop and evaluate a numerical uncertainty quantification tool for Navier-Stokes based simulations using an algorithm based on non-intrusive polynomial chaos, with an initial application to modeling of flows around partially-cavitating hydrofoils. Uncertainty quantification becomes a necessity due to the fact that the underlying analysis and simulation tools employed in marine hydrodynamics are typically applied with a unique set of input data and model variables, whereas realistic operating conditions are a superposition of numerous uncertainties under which the marine system of interest operates.
The biorobotic UUV can complete the motion of change depth through changing the central flapping angles of the two frontal flapping hydrofoils. And the biorobotic UUV also can complete the motion of change depth through changing the central flapping angles of all frontal flapping hydrofoils.
Naturally, the plane shares an affinity for runways, but if you see a nice seaside resort and the sea is calm enough, there is nothing to stoop a pilot going for a water landing, with a flick of the switch turning the landing wheels into hydrofoils for a safe sea landing.
Since Kim Jong Un assumed power in North Korea last year, Pyongyang has deployed rocket launchers, hydrofoils, Mi-2 helicopters and fighter jets along the western coast and conducted military drills, Chosun Ilbo said.
My biggest complaint is the fuel, so I've been doing some research on hydrofoils and trim tabs to see if that will help.
A boundary layer was attached to the two hydrofoils in order to be able to compute the flow near a solid wall, (Thomson et al., 1997).