Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64C—AEROPLANES; HELICOPTERS
  • B64C3/00—Wings
  • B64C3/38—Adjustment of complete wings or parts thereof
  • B64C3/44—Varying camber
  • B64C3/48—Varying camber by relatively-movable parts of wing structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63H—MARINE PROPULSION OR STEERING
  • B63H9/00—Marine propulsion provided directly by wind power
  • B63H9/04—Marine propulsion provided directly by wind power using sails or like wind-catching surfaces
  • B63H9/06—Types of sail; Constructional features of sails; Arrangements thereof on vessels
  • B63H9/061—Rigid sails; Aerofoil sails

Definitions

• the present invention is a reversible camber airfoil that can be used to power a vehicle such as a boat, etc.
• Prior art conventional sails have very low efficiency due to a lack of thickness, and therefore have a large amount of resistance to the wind; this resistance results in the boat or other vehicle "heeling" over in a strong wind.
• the present invention is a reversible camber asymmetrical airfoil comprised of a pivotable front member, a pivotable rear member, and a flexible outer covering.
• the front and rear members cooperate to form the contours of the suction surface of the airfoil; the pressure surface is formed by the flexible outer covering alone.
• the flexible outer covering encloses all moving parts, protecting them from ice and dust in addition to assuming the desired airfoil shape.
• the pivotable front and rear members are linked by means which synchronizes their movements.
• Figure 1 is a cutaway perspective view of the airfoil of the present invention.
• FIG. 2 is a closeup of the front and rear pivotable members. Description of the Preferred Embodiment
• the present invention is a reversible camber airfoil 10 as shown in cutaway perspective in Figure 1. It comprises a frame covered by a flexible outer covering or member, the frame comprising a series of pivotable front members 11 and pivotable rear members 12. All front members 11 are preferably, but not necessarily, enclosed in rigid front shell 14, and all rear members 12 are preferably, but not necessarily, enclosed in rigid rear shell 16.
• the purpose of shells 14 and 16 is to provide a smooth even surface for flexible outer member 18 to slide upon as the camber is reversed, as will be explained later.
• Front members 11 and rear members 12 are linked to each other by means which synchronizes their movement such that they pivot in unison but in opposite directions; this is illustrated in Figure 2 as a set of meshing gear teeth 20, but may be of any other type of linkage that allows the desired movement.
• front members 11 When front members 11 are in a first position rear members 12 are in a corresponding first position that is determined by gear teeth 20 or other synchronizing means. When front members 11 are moved from this first position forming an airfoil having a first camber to a second position forming an airfoil of the opposite camber, rear members 12 assume a corresponding second position. If they are linked by gear teeth as shown, the teeth must be relatively long since when the front and rear members are at one extreme of motion or the other their line of contact is not the same as it is when they are aligned with each other (i.e., when they are exactly between the two extremes of travel). The teeth must be long enough to accommodate this difference in the line of contact.
• Flexible outer member 18 is fastened to the airfoil only at its trailing edge; it may be glued or otherwise fastened to the trailing edge of rigid rear shell 16. Once it is fastened to rear shell 16, the amount of slack in flexible outer member 18 is one of the factors that determines the thickness of the resulting airfoil section; a large amount of slack produces a thick airfoil, and a small amount of slack produces a thin airfoil.
• cross members 34 either flexible or rigid, to the inside of flexible member 18 as shown in Figure 2 such that cross members 34 project through slots in shell 14 and rest on front members 11.
• Cross members 34 will support the weight of flexible member 18 yet will allow it to form a reversible camber airfoil shape v/hen front and rear members 11 and 12 are pivoted.
• Front members 11 pivot about vertical member 22, and rear members 12 pivot about vertical member 24.
• Vertical members 22 and 24 are rigidly fastened to turntable 26 at the bottom, and are supported by guy wires (not shown) that are attached to a similar turntable at the top (not shown) . These guy wires help transmit the force generated by the airfoil to the vehicle it is mounted on, just like the stays in a sailboard.
• Reversible motor 32 may be either an electric or a hydraulic motor; alternatively, double acting hydraulic cylinders could also be used to reverse the camber of airfoil 10.
• Turntable 26 which is mounted on the vehicle that is powered by airfoil 10, is necessary so that airfoil 10 can be properly aligned with the wind. If the vehicle that airfoil 10 is mounted on is moving north and the wind is out of the east, then the leading edge of airfoil 10 will have to be pointed to the east. If the wind should shift and come out of the west, then airfoil 10 will have to be rotated by rotating turntable 26 so that its leading edge is pointed to the west; at the same time the camber will have to be reversed, so that the airfoil's "lift" is always directed to the north.
• the only method known of designing a reversible camber airfoil of the present invention is an empirical one.
• An outline of the desired airfoil is drawn, then the front and rear members are drawn as in Figure 2.
• the length of flexible outer member 18 is determined.
• the length of flexible outer member 18 is one of the factors that determines the thickness of airfoil 10 (the other obviously is the thickness of front and rear members 11 and 12). The longer it is the more that front and rear members 11 and 12 can pivot to either position, thereby creating a thicker airfoil.
• front members 11 and rear members 12 are symmetrical about their centerlines. Further, when they are at one extreme of travel or the other to form an airfoil, the rounded part of the front members 11 forms the leading edge and the first portion of the contours of the curved or suction surface of the airfoil, while the corresponding side of rear members 12 forms the remainder of the contours of the curved or suction surface of the airfoil.
• the flat or pressure surface of the airfoil is formed by flexible member 18 which is stretched taut.
• the shape of the curved or suction surface of the airfoil is determined by the contours of front members 11 and rear members 12 when flexible outer member 18 is stretched over them, and the flat or pressure surface results from the fact that flexible member 18 is unsupported from a point just slightly downstream from the leading edge to the trailing edge and is stretched taut between these two points.
• Operation of the airfoil of the present invention is as follows. If airfoil 10 is on a boat and the boat changes course so that the wind direction changes from the port bow to the starboard bow, the entire airfoil will have to be rotated by means of turntable 26 (which is preferably operated by an electric or hydraulic motor, not shown) so that the leading edge of airfoil 10 is pointed into the wind. At the same time motor 32 will be energized to reverse the camber of airfoil 10 so that it continues to produce "lift" in the forward direction.
• turntable 26 which is preferably operated by an electric or hydraulic motor, not shown
• the present airfoil allows for considerable flexibility in its design.
• the thickness of the airfoil is a function of the shapes of front and rear members 11 and 12 and of the length of flexible outer member 18, which means that the final design can be tailored to fit a given set of conditions.
• airfoil 10 should be as light and strong as possible, which means that all components except flexible outer member 18 should be made of aluminum or other lightweight metal or of a fiber reinforced composite.
• Flexible outer member 18 should be of a material that is flexible, light in weight, and does not stretch; suitable materials are fiber glass and synthetics such as Kevlar.
• Flexible outer member 18 may also be coated on both sides with Teflon, so that ice buildup can be more readily removed and so that it will slide more easily on shells 14 and 16.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Ocean & Marine Engineering (AREA)
• Aviation & Aerospace Engineering (AREA)
• Wind Motors (AREA)

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• 1984
  • 1984-07-11 WO PCT/US1984/001073 patent/WO1985000573A1/en unknown
  • 1984-07-11 EP EP84902871A patent/EP0148939A1/de not_active Withdrawn

Non-Patent Citations (1)

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