Ships – Sail or control means therefor – Specific sail structure or arrangement
Patent
1993-10-18
1996-01-23
Swinehart, Edwin L.
Ships
Sail or control means therefor
Specific sail structure or arrangement
114102, B63H 904
Patent
active
054857996
DESCRIPTION:
BRIEF SUMMARY
This application is a PCT application. This application claims the priority date of Apr. 17, 1991 for French Patent No. 91 04719.
The present invention relates to a device comprising at least one element of aerodynamic shape, at least one part or zone of which can be folded up, for propulsion and/or lift using the effect of the relative wind.
More precisely, the invention relates to a device of the aforementioned type with great adjustable lift, which is intended for any craft which can be set in motion in the air, on water or on land, such as a boat, sailboard, aircraft, flying wing, kite, land yacht, etc. The invention is also applicable to the production of models of these locomotion or sport crafts.
Before going any further, for clear understanding of the prior art and of the invention, the meaning of expressions used in the present description and in the claims will be defined: is at an increased pressure (in other words, face of the element which receives the wind); reduced pressure; element of aerodynamic shape, or of one of its parts or zones, viewed in the direction of the relative displacement of the air with respect to the said elements; element of aerodynamic shape, or of one of its parts or zones, viewed in the direction of the relative displacement of the air with respect to the said element; in the direction of flow of the air; edge and passing between the pressure face and the suction face and at an equal distance from the latter: to the trailing edge; the skeleton of a profile. point.
There are known, for example from DE-1,531,328 LEMOIGNE, devices of the aforementioned type in which the said element has two faces designed to be located respectively on the pressure face side and the suction face side, at least one opening being provided to establish a passage of air from the pressure face side to the suction face side, and guide means being provided to direct the air emerging from the said opening on the suction face side, and give it a direction which is tangential to the said element.
The problem which is it sought to resolve by providing openings for the passage of air in such elements of aerodynamic shape is to prevent the boundary layer of the flow of air, on the suction face side, from "detaching" from the element in the region of the line of greatest hollow, which it tends to do when the element is curved. This detachment of the flow limits, and even decreases the aerodynamic performance. By allowing a passage of air from the pressure face to the suction face air is reinjected at a greater speed compared to that of the boundary layer which, thus reactivated, follows the aerodynamic shape of the element.
In doing so, however, it is necessary to avoid creating, especially on the suction face side, variations in shape which affect the aerodynamics of the element. Indeed, any alteration to this shape, however minimal this might be, generates disturbances in the flow of the boundary layer of air and promotes its detachment.
To improve the flow of the air, when the element of aerodynamic shape is a thick sail structure, LEMOIGNE proposes equipping such sail structures with traversing channels which are permanent means for guiding the air, which are materially defined by channel walls and whose cross-section decreases in the direction of the stream, the objective being thus to create a venturi tube. To the same end, where thin sails are concerned, LEMOIGNE proposes to equip them with nozzles which project greatly on the suction face side, hampering the profile of the sail structure in terms of aerodynamics.
The object of the present invention is to propose means which improve the flow of the air from the pressure face to the suction face, so that the air emerges on the suction face as a stream with the same direction and same sense as those of the overall flow on the suction face at the point of junction of the said stream and of the said overall flow, and this being: without discontinuity, without a hollow or any obstacle which, inter alia, forms a deflector), even when the passage of air
REFERENCES:
patent: 1567531 (1925-12-01), Magni
patent: 2373089 (1945-04-01), Allen et al.
patent: 2984199 (1961-05-01), Giewald
patent: 3053219 (1962-09-01), Coon
patent: 3598075 (1971-08-01), Kenney
patent: 4006701 (1977-02-01), Gorbellini
Adams, III W. Thad
Swinehart Edwin L.
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