Ships – Hull or hull adjunct employing fluid dynamic forces to... – Having hydrofoil
Patent
1984-05-08
1986-04-01
Barefoot, Galen L.
Ships
Hull or hull adjunct employing fluid dynamic forces to...
Having hydrofoil
B63B 128
Patent
active
045790760
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hydrofoil device (also called hydropter) with a tail unit, intended to be used on fast marine craft. It also embraces the marine craft equipped with this device. The use of hydrofoils is a technique increasingly in use in fast boats, with motor or with sail, in order to improve their performances above a certain speed, by replacing the lift of hydrostatic origin by the hydrodynamic lift of a system of submerged fins.
Two main types are currently used: relative to the surface of the water, are only partially submerged and cross the surface, normal functioning.
The first type has the advantage that it may lead to configurations where the marine craft is naturally stable relative to the surface of the water. On the other hand, it has the disadvantage of having a higher drag than the second type.
The second type on the other hand has no natural stability and must be piloted continuously. Some boats employing this type of hydrofoil are currently stabilised by an automatic pilot system acting upon rudders through the intermediary of hydraulic jacks. This leads to an expensive, heavy and complicated system.
SUMMARY AND OBJECTS OF THE PRESENT INVENTION
The present invention deals with a hydrofoil system related to the second type, but arranged to exhibit natural stability and automatic regulation of the depth of immersion without the action of a control system.
According to a feature of the invention, the principal bearing surface, which is totally immersed, during functioning, at a certain depth below the surface, is combined with a tail unit or auxiliary bearing surface which is elevated relative to the principal bearing surface, so as to become immersed when the system rises and whilst the principal surface is still totally immersed. The reduction in the lift exerted upon the tail unit then causes a reduction in the incidence of the principal surface and a correlative reduction in its lift, so that the system tends to immerse further.
Conversely, if the system tends to sink, the lift upon the tail unit increases, which causes an increase in the incidence of the principal surface and, correlatively, a rise of the system, so that stabilization finally occurs.
The tail unit is preferably in front of the principal bearing surface in the direction of progress of the boat.
It is already known from Dutch Patent No. 34.042 to associate an auxiliary bearing surface of controlled inclination with a principal bearing surface, but in the known arrangement, contrary to the invention, the auxiliary surface is at a lower level than that of the principal bearing surface, so that the automatic stabilization effect achieved by the invention cannot be obtained.
The accompanying drawing given by way of example illustrates embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in profile, in side elevation, of a device according to the invention.
FIG. 2 is a plan view of the same.
FIG. 3 shows an alternative embodiment.
FIG. 4 is a perspective view of an assembly comprising two tail units associated with one and the same principal surface.
FIG. 5 shows an embodiment of the articulation of the assembly of principal bearing surface, fuselage and tail unit.
FIG. 6 is a perspective view of a boat comprising three devices according to FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The embodiment illustrated in FIG. 1 comprises a principal bearing surface 3 which will henceforth be called "principal plane", or main foil it being understood that said suface may have a form other than that of a plane, and may be for example a biplane, with a forward horizontal tail unit or auxiliary foil 4 and a fuselage 5 connecting the two bearing elements.
The tail unit is located at a certain height 6 above the principal plane 3. The assembly is articulated by the axis of articulation 2 on a profiled strut 1, which supports a marine device, for example a boat.
The functioning of the device is as follows:
When deeply immersed below the surface of t
REFERENCES:
patent: 1186816 (1916-06-01), Meacham
patent: 2584347 (1952-02-01), Hazard
patent: 3141437 (1964-07-01), Bush et al.
patent: 3762353 (1973-10-01), Shutt
Barefoot Galen L.
Sotelo Jesus D.
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