| WO2007071384 | FLEXIBLE CONTROL SURFACE FOR AN AIRCRAFT |
| WO/2023/180449 | VEHICLE |
| US1194878A | 1916-08-15 | |||
| US2156403A | 1939-05-02 | |||
| US4606519A | 1986-08-19 | |||
| US1918897A | 1933-07-18 | |||
| GB192568A | 1923-02-08 | |||
| DE2361210A1 | 1975-06-12 |
| 1. | I, Larry Lee Smith, do claim the following: An airfoil comprising a leading edge; a trailing edge located longi¬ tudinally rearward of said leading edge; a continuous lower surface extend¬ ing from leading edge to said trailing edge, said lower surface defining a lower camber; a first generally fixed (which also may be semifixed, hinged, movable, alterable, expandable, or collapsable) upper surface extending rearwardly from said leading edge and terminating in at least one continu¬ ous vertical surface defining an offset forwardly of sa'id trailing edge, said first fixed upper surface defining a first positive upper camber por¬ tion; a second fixed upper surface extending rearwardly from said continu¬ ous vertical surface of said offset and defining a second upper camber portion, a planar member positioned on and coextensive with said second fixed upper surface, means attaching a rearward edge of said planar member to said airfoil inwardly of said trailing edge and means for moving said planar member from a first position in substantial alignment with said first fixed upper surface to form an extension of said first positive upper camber portion to second positions on and above said second fixed upper surface. |
| 2. | An airfoil according to claim 1 in which said second fixed upper sur¬ face has a forward end elevationally displaced from said first fixed upper surface and wherein said planar member has a rearward edge movably attached to said airfoil inwardly of said trailing edge. |
| 3. | An airfoil according to claim 2 in which said continuous vertical surface extends from said first fixed upper surface to said second fixed upper surface and in which said planar member has a forward edge movably positioned immediately adjacent said continuous vertical surface. |
| 4. | An airfoil according to claim 1 in which said second fixed upper sur¬ face and said planar member extend rearwardly toward said trailing edge. |
| 5. | An airfoil according to claim 1 in which said planar member has a rearward edge registering with said second fixed upper surface adjacent said trailing edge and wherein said planar member is movable toward and „, .„, .c_„„, „„_; J 3 £ t 1 __ _. , , u«α; _ i v.ni oαju cωuu IJ.ΛCU uμ ei. toll! JeHfc* . |
| 6. | An airfoil according to claim 1 in which means for bowing said planar member transversely is positioned in said airfoil whereby said membermay be shaped to form an upper positive camber portion and upper negative camber portion of said airfoil. |
| 7. | An airfoil comprising a leading edge; a trailing edge located longi¬ tudinally rearward of said leading edge; a continuous lower surface extend¬ ing from said leading edge to said trailing edge, said lower surface defin¬ ing a lower camber; a first generally fixed (which also may be semifixed, hinged, movable, alterable, expandable, or collapsable) upper surface ex¬ tending rearwardly from said leading edge and terminating in a stepped off¬ set forwardly of said trailing edge, at least two vertical surfaces and one horizontal surface defining said stepped offset, said first upper surface defining a positive upper camber portion; a second upper surface extending rearwardly from one of said vertical surfaces of said stepped offset, said second upper surface defining a second upper camber portion; a planar mem¬ ber positioned on and coextensive with said second upper surface, means movably attaching a rearward end of said planar member to said airfoil in¬ wardly of said trailing edge and means for moving said member in an arc based on said attachment means, said member being movable from a first position adjacent said second upper surface to a second position forming an extension of said first upper surface, said member defining a positive upper camber portion in said second position, a rectangular body movably positioned in said airfoil adjacent one of said vertical surfaces and de¬ fining the other one of said vertical surfaces and said horizontal surface. |
| 8. | An airfoil according to claim 7 in which said body movably positioned in said airfoil forms said stepped offset and means for moving said body from a first position below said first upper surface to a second position above said second upper surface. |
| 9. | An airfoil comprising a leading edge; a trailing edge located longi¬ tudinally rearward of said leading edge; a first fixed lower cambered sur¬ face ending in at least one vertical surface defining an offset forwardly of said trailing edge, said first fixed lower surface defining a negative, positive or planar or variable camber portion followed by at least one ver¬ tical offset followed by a second lower surface which terminates in the trailing edge, means attaching a rearward edge of said planar member to said airfoil inwardly of said trailing edge and means for moving said plan¬ ar member from a first position in substantial alignment with said first fixed lower surface to form an extension of said first lower camber portion to second positions below said second lower surface; a first generally fixed (which also may be hinged, movable, alterable, expandable, collaps¬ able or semifixed) upper surface extending rearwardly from said leading edge and terminating in at least one continuous vertical surface defining an offset forwardly of said trailing edge, said first fixed upper surface defining a first positive upper camber portion; a second fixed upper sur¬ face extending rearwardly from said continuous vertical surface of said offset and defining a second upper camber portion, a planar member posi¬ tioned on and coextensive with said second fixed upper surface, means at¬ taching a rearward edge of said planar member to said airfoil inwardly of said trailing edge and means formoving said planar member from a first po¬ sition insubstantial alignment with said first fixed upper surface to form an extension of said first fixed upper camber portion to second portion on and above said second fixed upper surface. |
| 10. | An airfoil comprising a leading edge; a trailing edge located longi¬ tudinally rearward of said leading edge; a first fixed lower cambered sur¬ face ending in a vertical surface defining at least one offset forwardly of said trailing edge, said first fixed lower surface defining a negative, positive, or planar or variable portion followed by at least one vertical offset followed by a second lower surface which terminates in the trailing edge, means attaching a rearward edge of said planar member to said airfoil inwardly of said trailing edge and means for moving said planar member from a first position in substantial alignment with said first fixed lower sur¬ face to form an extension of said first lower camber portion to second po¬ sitions below said second lower surface; a first generally fixed (which also may be hinged, movable, alterable, expandable, collapsable or semi¬ fixed) upper surface extending rearwardly from said leading edge and termi¬ nating in a stepped offset forwardly of said trailing edge, at least two vertical surfaces and one horizontal surface defining said stepped offset, said first upper surface defining a positive upper camber portion; a second upper surface extending rearwardly from one of said vertical surfaces of said stepped offset, said second upper surface defining a second upper cam¬ ber portion; a planar member positioned on and coextensive with said second upper surface, means movably attaching a rearward end of said planar member to said airfoil inwardly of said trailing edge and means for moving said member in an arc based on said attachment means, said member being movah"!■*■ trom a ±irst position adjacent said second upper surface to a second posi¬ tion forming an extension of said upper surface, said member defining a positive upper camber portion in said second position, a rectangular body movably positioned in said airfoil adjacent one of said vertical surfaces and defining the other one of said vertical surfaces and said horizontal surface. |
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to an airfoil having improved lift coefficients at operational angles of attack and more specifically the present inven¬ tion relates to an airfoil having upper camber portions that may be posi¬ tioned to form a single upper camber portion or several upper camber por¬ tions.
2. Description of the Prior Art
The primary concern with any airfoil design is two-fold; first to pro¬ duce a greater amount of lift without adversely increasing drag and second to enable the airfoil to function at greater angles of attack without stalling. With respect to the wing of an airplane for example, a design suitable for producing substantial lift at ]ow air speeds inherently pro¬ duces excessive drag at high air speeds and on the other hand a wing de- designed to fly with minimal drag at high air speeds generally fails to produce sufficient lift at low air speeds to maintain flight as during take-offs and landings. This latter condition results in the stalling of the wing as the angle of attack of the wing is increased in an effort to produce greater lift until the critical angle of attack is exceeded. lL is understood that an airfoil will stall at any air speed whenever the angle of attack of the airfoil to the free stream air flow exceeds a crit¬ ical angle of attack for the particular air foil. The prior art includes movable slots and/or flaps on the lead and trailing edges of the wing which change the cross sectional profile of the wing. The slots and/or flaps may be adjusted during flight for optimum performance of the wing at various flight conditions. At high air speeds the slots and/or flaps are fully retracted to give the wing a relatively thin streamlined pro¬ file reducing the drag acting thereon. At lower air speeds the slots and/ or flaps are extended downward to produce a greater camber on the wing which permits the wing to develop greater lift along with greater drag. The use of slots and/or flaps thus increase the aircraft's operational angles of attack through which the aircraft can safely operate, but be¬ cause of Lπe -lπc_t.-__. , JI_I U ili e en io.. oi τ_he SIQLS and/or xla τ* s is only advisable at relatively low air speeds and thus they are unable to improve the lift and stall characteristics of the wing at high cruising air speeds.
The present invention provides an airfoil with means of altering the
upper surfaces thereof so as to optionally form a relatively thin stream¬ lined profile having a single continuously extending upper surface forming a positive upper camber portion and alternately forming a first upper sur¬ face extending rearwardly from the leading edge defining a positive upper camber portion and a second upper surface rearwardly of said first upper surface and defining a second variable upper camber portion.
Although this airfoil is depicted as an illustration, the entire field of fluid dynamics involves other lifting bodies such as, for example, hy¬ drofoils, sails, vanes, fans, turbines, blades, winglets, rotary winged aircraft, propellers, as well as other such applications. Virtually any body which interacts with a free stream flow will experience improvements upon incorporation of the disclosed invention herein.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial perspective view of an airfoil embodying the con¬ cept of the present invention shown in relation to the fuselage of a fixed- wing aircraft;
FIG. 2 is a cross section of the airfoil taken on line 2-2 of FIG. 1 and showing a portion of the airfoil in a first position;
FIG. 3 is a cross section of an airfoil with a step configuration and showing a portion of the airfoil in a second position; and, a member or variable flap from the lower camber.
FIG. 4 is a partial perspective view of an airfoil, a portion thereof being movable into and out of a cavity in the fuselage of a fixed-wing aircraft.
FIG. 5 is a cross section of an airfoil with a step configuration and showing another portion thereof in a second position.
SUMMARY OF THE INVENTION
An airfoil according to the concept of the present invention is dis¬ closed as an elongated wing member of a fixed wing aircraft and has a lead¬ ing edge and a trailing edge. A laterally extending offset is formed in the upper surface of the airfoil so as to form first an second upper sm— faces, the first upper surface defining a generally positive upper camber portion and the second upper surface defining a generally negative camber portion. A movable flap extends coextensively with the second upper sur¬ face and is movable above an uppermost position to below where it forms a continuation of the first upper surface definingan upper camber portion
of the airfoil to a lowermost position where it forms a generally negative, positive, planar or variable upper camber portion.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An airfoil according to the present invention is indicated generally by the numeral 10 in FIG. 1 illustrated as a wing member of a fixed-wing air¬ craft. As a wing member, the airfoil generally includes a root section 11 by which it is secured to the fuselage 12 of the aircraft and a wing tip 13 defining the outer end of the wing member. A leading edge 14 and a longi¬ tudinally displaced trailing edge 15 extend between the root section 11 and the wing tip 13 and together define the planform of the airfoil 10.
Control surfaces such as an aileron 16 and flap 17 may likewise be in¬ corporated in the airfoil 10. A longitudinally extending offset 18 defined by a vertical surface is formed in the upper surface of the airfoil 10 and as illustrated it extends from the fuselage 12 to the wing tip 13 and it will be appreciated that it need not extend completely therebetween. The airfoil incorporating the laterally extending offset 18 is described in US. Pat. No.4,606,519 issued Aug. 19, 1986 to the present applicant and another and the present invention comprises an improvement with respect thereto in that the airfoil of said patent disclosed first and second fixed upper sur¬ faces of the airfoil separated by an offset forwardly of the trailing edge of the airfoil so as to be positioned on different vertical elevations whereas the airfoil of the present invention, see FIG. 2, has a leading edge 14 and a first fixed upper surface 20 extending between the leading edge 14 and the offset 18 and a second upper surface 21 extending between the offset 18 and the trailing edge 15 of the airfoil. A member or flap 19 extends between the offset 18 and the trailing edge 15 and is hingedly affixed to the airfoil at or adjacent the trailing edge 15, the member or flap 19 being movable in an arc based on the point of attachment thereof with the trailing edge 15 of the airfoil. The airfoil is provided with means 22 which may be mechanical, hydraulic, or pneumatically actuated for moving the member or flap 19 vertically so that it may be positioned in a first upper position as shown in broken lines and the reference numeral 19 A where it forms s continuous extension of the first upper surface 20 of the airfoil as it extends therefrom to the trailing edge 15 and as the member or flap 19 may be bowed transversely, it may be bowed by mechani¬ cal, hydraulic or pneumatically actuated means to form an extension of the irst fixed upper surface of the airfoil to comprise a generally positive or
generally negative, or planar, or variable upper camber portion or it may be pre-bowed.
Alternately, flap 19, and still referring to Fig. 2 of the drawings, it may be lowered by the means 22 to the position on the solid line 19 where if it is planar it will form a generall negative, positive, planar or var¬ iable upper camber portion of the airfoil. Alternately it may be positioned at various locations above and between said upper and lower positions.
By referring to FIG. 3 of the drawings, a cross section of an airfoil similar to that of FIG. 2 may be seen and wherein a leading edge 23 and a trailing edge 24 define the width of the airfoil and a first upper section 25 extending rearwardly from the leading edge 23 forms a positive upper camber portion terminating at an offset stepped configuration 26 running longitudinally of the airfoil and incorporating a first vertical surface 27 and a second horizontally spaced vertical surface 28 connected by a trans¬ versely arched substantially horizontally disposed section 29. The second vertical surface 28 is located at the forward edge of a second upper sur¬ face 30 which if bowed upwardly forms a second positive upper camber portion and if planar or bowed downwardly intermediate it edges, forms a negative upper camber portion. As illustrated in FIG. 3 a member or flap 31 is hingedly affixed to the airfoil adjacent the trailing edge 24 thereof and extends forwardly thereof and is movable from a lowermost portion adjacent the second upper surface 30 to an uppermost position shown in broken lines 31A where it forms a continuation of the first upper section 25 of the air¬ foil. In FIG. 5 of the drawings the member or flap 31 is hingedly affixed to the airfoil at the trailing edge 24 thereof and the horizontally dis¬ posed section 29 forms the middle step in a stepped configuration defined by the first vertical surface 27 and second vertical surface 28 . The forward edge of the member or flap 31 may be retractable. A vertically movable body may form the offset step 26 which is movable from the posi¬ tion shown in solid lines in FIG. 3 to the upper broken line 31A by mechan¬ ical, hydraulic, or pneumatically actuated means 32. The member or flap 31 may be moved above 19A of FIG. 2 by -means 33 which may be mechanical, hydraulic, or pneumatically actuated. The member or flap 32 in uppermost position extends the first upper surface 25 forming a positive upper camber portion, the offset step 26 wit i h arched middle portion there¬ of forming a second positive camber portion, and the second upper sur¬ face 30 if bowed upwardly forming a third positive upper camber por¬ tion or if planar or bowed downwardly intermediate its edges forming a negative upper camber portion. As illustrated in FIG. 3 a member
or flap 36 is hingedly affixed to the airfoil adjacent or forward of the trailing edge 24 thereof and extends forwardly thereof and is movable in an arc from the trailingward surface defining a lower camber of the airfoil. The airfoil is provided with means 37 which may be mechanical hydraulic or pneumatically actuated for moving the member or flap 36.
Those skilled in the art will observe that by changing the relative pos¬ ition of the member or flap 19 of the airfoil illustrated in FIGS. 1 and 2 of the drawings or the member or flap 30 as illustrated in FIG. 3 of the drawings, the lift and the angle of attack at which the lift is most effi¬ cient may be varied at will by the operator to control the lift at a pre¬ determined angle of attack and/or speed of the airfoil with respect to the airflow thereover.
Those skilled in the art will observe that it is possible to move the member or flap 19 of the embodiment of FIGS. 1 and 2 of the disclosure or the member of flap 31 of the embodiment of FIG. 3 of the disclosure longi¬ tudinally of the airfoil, as for example in a fixed-wing aircraft the mem¬ ber or flaps may be moved toward and into receptive chambers 34 formed in the lower portion of the fuselage 35 of the aircraft and it will be seen that in such event the effective area of the members or flaps concerned may be additionally varied with respect to the upper surfaces of the airfoil enabling a further control of the aircraft with respect to the left gener¬ ated thereby by the positive and/or negative upper camber portions of the airfoil.
It will thus be seen that the improvement in airfoils as herein disclosed incorporates a substantial improvement in the aerodynamic characteristics thereof occasioned by the discontinuity generated by the offset in the upper surface of the airfoil and additionally and most importantly the ability of the structure of the present invention to directly control the degree of aerodynamic improvement and/or lift or unobstructed airflow with respect to such an airfoil through the use of the movable members or flaps positioned in the airfoil immediately rearwardly of the offset formed therein.
• Although but two embodiments of the present invention have been illus¬ trated and described, it will be apμciieiiL Lo those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention and having thus described my invention what I claim is: