A hybrid transonic-subsonic airfoil is provided that combines subsonic and transonic features for achieving simultaneously acceptable aerodynamic characteristics at low subsonic and high transonic Mach numbers.
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1. A hybrid aerofoil configured for a wing of an aircraft, the hybrid aerofoil being profiled for transonic and subsonic flight conditions of the wing and having a respective transonic design point and a respective subsonic design point, said aerofoil comprising a leading edge, a trailing edge and a
1. A hybrid aerofoil configured for a wing of an aircraft, the hybrid aerofoil being profiled for transonic and subsonic flight conditions of the wing and having a respective transonic design point and a respective subsonic design point, said aerofoil comprising a leading edge, a trailing edge and a chord dimension therebetween, and comprising: an upstream portion having an upstream profile characteristic of subsonic aerofoils including a relatively rounded leading edge, wherein said upstream profile is configured for reducing a magnitude of a suction peak and retarding development of trailing edge flow separation at said subsonic design point including subsonic high lift coefficient flight conditions as compared with that obtained with a reference transonic aerofoil having a relatively sharp leading edge, and comprising a camber greater than 1% of said chord dimension at a position less than about 30% along said chord from said leading edge at said transonic and subsonic flight conditions, and a camber greater than 2% at a position greater than 60% along said chord from said leading edge; anda downstream portion including a mid-portion having a mid-portion profile characteristic of transonic aerofoils, wherein said mid-portion profile is shaped for delaying formation of shockwaves and minimizing wave drag at said transonic design point including transonic Mach numbers,wherein said camber has a non-negative camber distribution with respect to the chord,wherein said camber distribution comprises maxima at a position greater than 60% of said chord from said leading edge, andwherein said upstream portion comprises a leading edge radius of greater than 2.5% of said chord dimension at said subsonic design point and at said transonic design point. 2. The aerofoil according to claim 1, wherein the aerofoil comprises a leading edge radius larger than that of said reference transonic aerofoil. 3. The aerofoil according to claim 1, wherein said camber is greater than 1% of said chord dimension between 5% and 30% of said chord dimension from a leading edge thereof. 4. The aerofoil according to claim 1, wherein said camber is substantially less than 5% of said chord dimension between 30% and 60% of said chord from said leading edge. 5. The aerofoil according to claim 1, wherein said camber is substantially more than 2% of said chord dimension between 30% and 60% of said chord from said leading edge. 6. The aerofoil according to claim 1, wherein the aerofoil comprises a thickness thicker than said reference transonic aerofoil at chord locations between 1% of said chord dimension and 5% of said chord from a leading edge thereof. 7. The aerofoil according to claim 1, wherein the aerofoil comprises a camber distribution that is intermediate with respect to that obtained with said reference transonic aerofoil and that obtained with a reference subsonic aerofoil, said reference subsonic aerofoil being configured having a similar thickness/chord ratio as said hybrid aerofoil. 8. The aerofoil according to claim 1, wherein said mid-portion is defined between from 25% and 60% along said chord from the leading edge. 9. The aerofoil according to claim 1, wherein said aerofoil comprises an area distribution along said chord, and wherein said aerofoil comprises a location of maximum thickness thereof, such that to allow a portion of the aerofoil downstream of said maximum thickness location for turbulent pressure recovery. 10. The aerofoil according to claim 1, said aerofoil defining a continuous geometric enclosure extending between a leading edge and a trialing edge thereof, for at least one flight condition. 11. A wing for an air vehicle having the aerofoil as defined in claim 1. 12. The aerofoil according to claim 1, wherein said camber is greater than 2% of said chord dimension at a position less than 30% along said chord from said leading edge at transonic and subsonic flight conditions. 13. The aerofoil according to claim 1, wherein said camber is greater than 1% of said chord dimension at a position less than 20% along said chord from said leading edge at transonic and subsonic flight conditions. 14. The aerofoil according to claim 1, wherein said maxima is the maximum value of camber in said camber distribution. 15. The aerofoil according to claim 1, wherein said camber distribution comprises additional maxima at a position less than 60% of said chord from said leading edge. 16. The aerofoil according to claim 15, wherein said additional maxima has a camber value that is less than the camber value of the first-mentioned maxima. 17. The aerofoil according to claim 1, wherein said downstream portion includes an aft portion shaped for controlling aerofoil lift and pitching moment. 18. The aerofoil according to claim 17, wherein said aft portion is defined between 60% and 100% along said chord of the aerofoil from the leading edge. 19. A hybrid aerofoil configured for a wing of an aircraft, the hybrid aerofoil being profiled for transonic and subsonic flight conditions of the wing and having a respective transonic design point and a respective subsonic design point, said aerofoil comprising a leading edge, a trailing edge and a chord dimension therebetween, and comprising: an upstream portion having an upstream profile characteristic of subsonic aerofoils including a relatively rounded leading edge, wherein said upstream profile is configured for reducing a magnitude of a suction peak and retarding development of trailing edge flow separation at said subsonic design point including subsonic high lift coefficient flight conditions as compared with that obtained with a reference transonic aerofoil having a relatively sharper leading edge, and comprising a camber greater than 1% of said chord dimension at a position less than 30% along said chord from said leading edge at said transonic and subsonic flight conditions, and a chamber greater than 2% at a position greater than 60% along said chord from said leading edge; anda downstream portion including a mid-portion having a mid-portion profile characteristic of transonic aerofoils, wherein said mid-portion profile is shaped for delaying formation of shockwaves and minimizing wave drag at said transonic design point including transonic Mach numbers,wherein said aerofoil has a smooth cross-sectional distribution having a maximum thickness value at a mid-portion of said aerofoil greater than 30% of said chord from said leading edge,wherein said camber has a non-negative camber distribution with respect to the chord,wherein said camber distribution comprises maxima at a position greater than 60% of said chord from said leading edge, andwherein said upstream portion comprises a leading edge radius of greater than 2.5% of said chord dimensions at said subsonic design point and said transonic design point. 20. A hybrid aerofoil configured for a wing of an aircraft, the hybrid aerofoil being profiled for transonic and subsonic flight conditions and having a respective transonic design point and a respective subsonic design point, comprising: an upstream portion having a profile including a relatively rounded leading edge radius, configured for providing subsonic-like aerodynamic performance to reduce a magnitude of a suction peak and retard development of trailing edge flow separation at said subsonic design point including subsonic high lift coefficient flight conditions as compared with that obtained with a reference transonic aerofoil having a relatively pointed leading edge radius; anda downstream portion including a mid-portion having a profile configured for providing transonic-like aerodynamic performance to delay formation of shockwaves and minimize wave drag at said transonic design point including transonic Mach numbers,wherein said aerofoil comprises a camber having a non-negative camber distribution with respect to the chord,wherein said camber distribution comprises first maxima that is greater than 2% at a position not less than 60% of said chord from said leading edge, and second maxima that is greater than 1% at a position less than 60% of said chord from said leading edge; andwherein said upstream portion comprises a leading edge radius of greater than 2.5% of said chord dimension at said subsonic design point and at said transonic design point. 21. The aerofoil according to claim 20, wherein the aerofoil is configured for providing a pressure distribution at a transonic design point thereof that is more favorable than that obtained with a reference subsonic aerofoil, at said transonic design point. 22. The aerofoil according to claim 20, wherein the aerofoil is configured for providing a pressure distribution at a subsonic design point that is more favorable than that obtained with said reference transonic aerofoil at said subsonic design point, said reference transonic aerofoil being configured having a similar thickness/chord ratio as said hybrid aerofoil. 23. A wing for an air vehicle having the aerofoil as defined in claim 20. 24. A method for profiling an aerofoil for a wing of an aircraft, the hybrid aerofoil being optimized for transonic and subsonic flight conditions having a respective transonic design point and a subsonic design point, comprising: (a) profiling an upstream portion thereof in a manner including providing a relatively rounded leading edge to provide the aerofoil with subsonic-like performance at a subsonic design point to reduce a magnitude of a suction peak and retarding development of trailing edge flow separation at said subsonic design point including subsonic high lift coefficient flight conditions as compared with that obtained with a reference transonic aerofoil having a relatively pointed leading edge;(b) concurrently profiling a downstream portion thereof in a manner to provide the aerofoil with transonic-like performance at a transonic design point to delay formation of shockwaves and minimizing wave drag at said transonic design point including transonic Mach numbers;(c) providing a camber having a non-negative camber distribution with respect to the chord, wherein said camber distribution comprises maxima at a position not less than 60% of said chord from said leading edge, and further comprises a camber value greater than 1% of said chord dimension at a position less than 30% along said chord from said leading edge and a camber value greater than 2% of said chord dimension at a position greater than 60% along said chord from said leading edge; andwherein said upstream portion comprises a leading edge radius of greater than 2.5% of said chord dimension at said subsonic design point and at said transonic design point. 25. The method according to claim 24, wherein step (b) comprises providing a smooth cross-sectional distribution for the aerofoil having a maximum value at a mid-portion of said aerofoil greater than 30% of a dimension of chord of said aerofoil from a leading edge thereof. 26. The method according to claim 24, wherein steps (a) and (b) are applied to a starting aerodynamic profile obtained for a reference subsonic aerofoil, said reference subsonic aerofoil being configured having a similar thickness/chord ratio as said hybrid aerofoil. 27. The method according to claim 24, wherein steps (a) and (b) are applied to a starting aerodynamic profile obtained for said reference transonic aerofoil. 28. The method according to claim 24, wherein step (a) comprises generating a camber greater than 1% of said chord dimension at a position less than 30% along said chord from said leading edge.
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