Helicopter blade

Claim 2

A helicopter blade having a chord, thickness, and a span and further having: A. a root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and being shaped to define an airfoil of cross section in accordance with the equation:

Claim 3

A blade according to claim 1 wherein said root portion is thicker than said central portion, and wherein said tip portion is thinner than said central portion.

Claim 4

Apparatus according to claim 1 wherein said tip portion is also defined by the given equation.

Claim 5

A helicopter blade having a chord, thickness, and a span and further having: A. a root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and being shaped to define an air-foil of cross section defined by the coordinate system: X/C Yu/t YL/t 0.0125 0.1863 -.1526 0.025 0.2737 -.221 0.05 0.387 -.2993 0.075 0.45 -.3395 0.1 0.4926 -.3642 0.15 0.5442 -.3937 0.2 0.5734 -.4087 0.25 0.5842 -.4147 0.3 0.5815 -.4122 0.4 0.5578 -.3959 0.5 0.5109 -.3627 0.6 0.4434 -.3145 0.7 0.3553 -.2509 0.8 0.2486 -.1745 0.9 0.13 -.0905 0.9750.0345 -.0244 where X is a chord station measured form the blade leading edge, C is the chord dimension, t is maximum blade thickness, Yu is the upper airfoil location at station X and YL is the lower airfoil location at station X and where the leading edge radii can be defined by the following equations: ( Rho u/c) (t/c)2 1.018 ( Rho L/c) (t/c)2 0.7313 where Rho u is the leading edge radius of the blade upper airfoil section taken from a point on the blade chord, wherein C is the chord dimension, wherein t is maximum blade thickness and where Rho L is the leading edge radius of the blade lower airfoil section taken from a point on the blade chord and within a range of + or - 3 percent of the values of Yu/t, YL/t, Rho u and Rho L so determined.

Claim 6

A helicopter blade having a chord, thickness, and a span and further having: A. a root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and being shaped to define an air-foil of cross section defined by the coordinate system: X/C Yu/t YL/t 0.0125 0.1863 -.1526 0.025 0.2737 -.221 0.05 0.387 -.2993 0.075 0.45 -.3395 0.1 0.4926 -.3642 0.15 0.5442 -.3937 0.2 0.5734 -.4087 0.25 0.5842 -.4147 0.3 0.5815 -.4122 0.4 0.5578 -.3959 0.5 0.5109 -.3627 0.6 0.4434 -.3145 0.7 0.3553 -.2509 0.8 0.2486 -.1745 0.9 0.13 -.0905 0.9750.0345 -.0244 where X is a chord station measured form the blade leading edge, C is the chord dimension, t is maximum blade thickness, Yu is the upper airfoil location at station X and YL is the lower airfoil location at station X and where the leading edge radii can be defined by the following equations: ( Rho u/c) (t/c)2 1.018 ( Rho L/c) (t/c)2 0.7313 where Rho u is the leading edge radius of the blade upper airfoil section taken from a point on the blade chord, wherein C is the chord dimension, wherein t is maximum blade thickness and where Rho L is the leading edge radius of the blade lower airfoil section taken from a point on the blade chord and within a range of + or - 3 percent of the values of Yu/t, YL/t, Rho u and Rho L so determined.

Claim 7

A blade according to claim 4 wherein said root portion is thicker than said central portion and wherein said tip portion is thinner than said central portion.

Claim 8

Apparatus according to claim 4 wherein said tip portion is also defined by said coordinate system.

Claim 9

A helicopter blade having a thickness, a span and a chord, and further having: A. A root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and being shaped to define an airfoil of cross section defined by the coordinate system: X/C Yu/C YL/C 0.00 0.00 .00 0.0125 0.0177 -.0145 0.025 0.0264 -.0210 0.05 0.03677 -.02843 0.075 0.04275 -.03225 0.10 0.0468 -.03460 0.15 0.0517 -.0374 0.20 0.05447 -.03883 0.25 0.0555 -0.0394 0.30 0.05524 -.03916 0.40 0.05299 -.03761 0.50 0.04854 -.03446 0.60 0.04212 -.02988 0.70 0.03375 -.02384 0.80 0.02362 -.01658 0.90 0.01235 -.00864 0.975 0.00328 -.00232 1.0 0.00 .00 where X is the station along the blade chord, C is the blade chord dimension, Y is the location of the upper airfoil surface at station X, and YL is the location of the lower airfoil surface at station X, and wherein the leading edge radius of the upper airfoil is 0.010 taken from a point on the blade chord and wherein the leading edge radius of the lower airfoil is 0.0066 taken from a point on the blade chord and within a range of + or - 3 percent of the given values of Yu/C and YL/C so determined.

Claim 10

A helicopter blade having a thickness, a span and a chord, and further having: A. A root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and being shaped to define an airfoil of cross section defined by the coordinate system: X/C Yu/C YL/C 0.00 0.00 .00 0.0125 0.0177 -.0145 0.025 0.0264 -.0210 0.05 0.03677 -.02843 0.075 0.04275 -.03225 0.10 0.0468 -.03460 0.15 0.0517 -.0374 0.20 0.05447 -.03883 0.25 0.0555 -0.0394 0.30 0.05524 -.03916 0.40 0.05299 -.03761 0.50 0.04854 -.03446 0.60 0.04212 -.02988 0.70 0.03375 -.02384 0.80 0.02362 -.01658 0.90 0.01235 -.00864 0.975 0.00328 -.00232 1.0 0.00 .00 where X is the station along the blade chord, C is the blade chord dimension, Y is the location of the upper airfoil surface at station X, and YL is the location of the lower airfoil surface at station X, and wherein the leading edge radius of the upper airfoil is 0.010 taken from a point on the blade chord and wherein the leading edge radius of the lower airfoil is 0.0066 taken from a point on the blade chord and within a range of + or - 3 percent of the given values of Yu/C and YL/C so determined.

Claim 11

A blade according to claim 7 wherein said root portion is thicker than said central portion and wherein said tip portion is thinner than said central portion.

Claim 12

Apparatus according to claim 7 wherein said tip portion is also defined by said coordinate system.

Claim 13

A helicopter blade having a thickness, a span and a chord, and further having: A. a root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and having a thickness of about 9.5 percent chord dimension and a forward camber, with maximum camber at about 0.8 + or - 0.05 percent chord dimension and being located forward of the 30 percent chord station and shaped so as to have a blade pitching moment coefficient within the range + or - 0.03 before moment divergence at all Mach numbers below 0.75 to thereby produce low blade pitching moments without sacrificing higher maximum lift coefficient and drag divergence.

Claim 14

A helicopter blade having a thickness, a span and a chord, and further having: A. a root portion adapted to be connected to a rotor hub, B. a tip portion defining the blade portion farthest from said root portion, C. a central portion extending between and attached to said root portion and said tip portion and cooperating therewith to define blade span and having a thickness of about 9.5 percent chord dimension and a forward camber, with maximum camber at about 0.8 + or - 0.05 percent chord dimension and being located forward of the 30 percent chord station and shaped so as to have a blade pitching moment coefficient within the range + or - 0.03 before moment divergence at all Mach numbers below 0.75 to thereby produce low blade pitching moments without sacrificing higher maximum lift coefficient and drag divergence.