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Patent US3822105A successfully refreshed from Google Patents.
US3822105A
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Helicopter blade
Assignee: RTX Corp
•
Filing: 1973-06-04
•
Granted: 1974-07-02
•
Expires: 1993-06-04
Abstract
Abstract A helicopter blade is shaped to have a tip of selected twist, camber, planform, thickness distribution, sweep and airfoil so as to increase rotor operating efficiency, reduce rotor noise, and to reduce or eliminate rotor instability.
Inventors
- 👤 W Jepson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:05
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/46; B64C27/463; B64C27/467
Claims Analysis
Total Claims: 264
Claim 1
Independent Claim
144 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have: 1. a generally negative non-linear twist of values ranging between -1* and about -8*. 2. a substantially constant chord dimension throughout most of its span, 3. a trapezoidal tip, 4. a thickness between 6 and 10 chord dimension, 5. and being cambered with the maximum camber forward of the 50 percent chord station.
Claim 2
Dependent Claim
144 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have: 1. a generally negative non-linear twist of values ranging between -1* and about -8*. 2. a substantially constant chord dimension throughout most of its span, 3. a trapezoidal tip, 4. a thickness between 6 and 10 chord dimension, 5. and being cambered with the maximum camber forward of the 50 percent chord station.
Claim 3
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 4
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 5
Dependent Claim
10 words
a planform of constant chord dimension with a trapezoidal tip,
Claim 6
Dependent Claim
10 words
a planform of constant chord dimension with a trapezoidal tip,
Claim 7
Dependent Claim
10 words
A substantially constant chord dimension throughout most of its span,
Claim 8
Dependent Claim
10 words
A substantially constant chord dimension throughout most of its span,
Claim 9
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 10
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 11
Dependent Claim
10 words
a planform of constant chord dimension with a trapezoidal tip,
Claim 12
Dependent Claim
10 words
a planform of constant chord dimension with a trapezoidal tip,
Claim 13
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 14
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 15
Dependent Claim
6 words
a planform of constant chord dimension,
Claim 16
Dependent Claim
6 words
a planform of constant chord dimension,
Claim 17
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 18
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 19
Dependent Claim
11 words
a planform of constant chord dimension throughout most of its span,
Claim 20
Dependent Claim
11 words
a planform of constant chord dimension throughout most of its span,
Claim 21
Dependent Claim
12 words
a planform of constant chord dimension throughout most of its span, and
Claim 22
Dependent Claim
12 words
a planform of constant chord dimension throughout most of its span, and
Claim 23
Dependent Claim
11 words
a planform of constant chord dimension throughout most of its span,
Claim 24
Dependent Claim
11 words
a planform of constant chord dimension throughout most of its span,
Claim 25
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 26
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 27
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 28
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 29
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 30
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 31
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 32
Dependent Claim
10 words
a substantially constant chord dimension throughout most of its span,
Claim 33
Dependent Claim
3 words
a trapezoidal tip.
Claim 34
Dependent Claim
3 words
a trapezoidal tip.
Claim 35
Dependent Claim
27 words
A blade according to claim 1 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 36
Dependent Claim
3 words
a trapezoidal tip.
Claim 37
Dependent Claim
3 words
a trapezoidal tip.
Claim 38
Dependent Claim
3 words
a trapezoidal tip,
Claim 39
Dependent Claim
3 words
a trapezoidal tip,
Claim 40
Dependent Claim
3 words
a trapezoidal tip,
Claim 41
Dependent Claim
3 words
a trapezoidal tip,
Claim 42
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 43
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 44
Dependent Claim
3 words
a trapezoidal tip,
Claim 45
Dependent Claim
3 words
a trapezoidal tip,
Claim 46
Dependent Claim
3 words
a trapezoidal tip,
Claim 47
Dependent Claim
3 words
a trapezoidal tip,
Claim 48
Dependent Claim
21 words
having an airfoil cross section shaped to increase in lift capacity and improve rotor efficiency, and having low pitching moments, and
Claim 49
Dependent Claim
21 words
having an airfoil cross section shaped to increase in lift capacity and improve rotor efficiency, and having low pitching moments, and
Claim 50
Dependent Claim
20 words
having an airfoil cross section shaped to increase in lift capacity and improve rotor efficiency, and having low pitching moments.
Claim 51
Dependent Claim
20 words
having an airfoil cross section shaped to increase in lift capacity and improve rotor efficiency, and having low pitching moments.
Claim 52
Dependent Claim
9 words
a thickness of about 9.5 percent chord dimension, and
Claim 53
Dependent Claim
9 words
a thickness of about 9.5 percent chord dimension, and
Claim 54
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 55
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 56
Dependent Claim
8 words
a thickness of about 9.5 percent chord dimension,
Claim 57
Dependent Claim
8 words
a thickness of about 9.5 percent chord dimension,
Claim 58
Dependent Claim
4 words
a rearwardly swept tip,
Claim 59
Dependent Claim
4 words
a rearwardly swept tip,
Claim 60
Dependent Claim
15 words
and having an airfoil cross section shaped to increase in lift capacity with increased angle-of-attack.
Claim 61
Dependent Claim
15 words
and having an airfoil cross section shaped to increase in lift capacity with increased angle-of-attack.
Claim 62
Dependent Claim
29 words
a rearwardly swept tip shaped to establish a tip lift vector offset from blade elastic axis to produce a nose-up moment on the advancing blade during high speed flight,
Claim 63
Dependent Claim
29 words
a rearwardly swept tip shaped to establish a tip lift vector offset from blade elastic axis to produce a nose-up moment on the advancing blade during high speed flight,
Claim 64
Dependent Claim
49 words
A trapezoidal tip commencing at the span 95 percent station + or - 2 percent and reducing uniformly in chord dimension so that the blade tip chord is about 60 percent of the blade chord dimension and so that the tip aerodynamic center remains at the same chord station,
Claim 65
Dependent Claim
49 words
A trapezoidal tip commencing at the span 95 percent station + or - 2 percent and reducing uniformly in chord dimension so that the blade tip chord is about 60 percent of the blade chord dimension and so that the tip aerodynamic center remains at the same chord station,
Claim 66
Dependent Claim
126 words
A blade according to claim 1 wherein said tip portion constitutes the outer 18 percent of the blade span plus or minus 2 percent blade span for three bladed rotors, the outer 15.5 percent of the blade span plus or minus 2 percent blade span for four bladed rotors, the outer 14 percent of the blade span plus or minus 2 percent blade span for five bladed rotors, the outer 13 percent of the blade span plus or minus 2 percent blade span for six bladed rotors, the outer 12.5 percent of the blade span, plus or minus 2 percent blade span for seven bladed rotors and the outer 12 percent of the blade span plus or minus 2 percent blade span for eight bladed rotors.
Claim 67
Dependent Claim
9 words
a thickness of about 9.5 percent chord dimension, and
Claim 68
Dependent Claim
9 words
a thickness of about 9.5 percent chord dimension, and
Claim 69
Dependent Claim
15 words
maximum camber of about 0.8 percent chord dimension at about the 27 percent chord station.
Claim 70
Dependent Claim
15 words
maximum camber of about 0.8 percent chord dimension at about the 27 percent chord station.
Claim 71
Dependent Claim
8 words
a thickness about 9.5 percent chord dimension, and
Claim 72
Dependent Claim
8 words
a thickness about 9.5 percent chord dimension, and
Claim 73
Dependent Claim
8 words
a thickness about 9.5 percent chord dimension, and
Claim 74
Dependent Claim
8 words
a thickness about 9.5 percent chord dimension, and
Claim 75
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 76
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 77
Dependent Claim
16 words
maximum camber of about 0.8 percent chord dimension at about the 27 percent chord station, and
Claim 78
Dependent Claim
16 words
maximum camber of about 0.8 percent chord dimension at about the 27 percent chord station, and
Claim 79
Dependent Claim
13 words
being cambered with the maximum camber forward of the 50 percent chord station.
Claim 80
Dependent Claim
13 words
being cambered with the maximum camber forward of the 50 percent chord station.
Claim 81
Dependent Claim
15 words
maximum camber of about 0.8 percent chord dimension at about the 27 percent chord station.
Claim 82
Dependent Claim
15 words
maximum camber of about 0.8 percent chord dimension at about the 27 percent chord station.
Claim 83
Dependent Claim
30 words
a rearwardly swept tip shaped to establish a tip lift vector offset from the blade elastic axis to produce a nose-up moment on the advancing blade during high speed flight.
Claim 84
Dependent Claim
30 words
a rearwardly swept tip shaped to establish a tip lift vector offset from the blade elastic axis to produce a nose-up moment on the advancing blade during high speed flight.
Claim 85
Dependent Claim
219 words
A blade according to claim 1 wherein said blade central portion has a twist ranging from 0* to -20* and said generally non-linear tip twist commences at about the 88 percent mark span station + or - 2 span station and extends to the blade tip for eight bladed rotors, at about the 87.5 percent span station + or - 2 percent span station and extends to the blade tip for seven bladed rotors, at about the 87 percent span station + or - 2 percent span station and extends to the blade tip for six bladed rotors, at about the 86 percent span station + or - 2 percent span station and extends to the blade tip for five bladed rotors, at about the 84.5 percent span station + or - 2 percent span station and extends to the blade tip for four bladed rotors, and at about the 82 percent span station + or - 2 percent span station and extends to the blade tip for three bladed rotors, at about the 77.5 percent span station + or - 2 percent span and extends to the blade tip for two bladed rotors, and at about the 71 percent span station + or - 2 percent span and extends to the blade tip for a one bladed rotor.
Claim 86
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 87
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 88
Dependent Claim
11 words
a thickness of between 6 and 10 percent chord dimension, and
Claim 89
Dependent Claim
11 words
a thickness of between 6 and 10 percent chord dimension, and
Claim 90
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 91
Dependent Claim
10 words
a thickness between 6 and 10 percent chord dimension, and
Claim 92
Dependent Claim
67 words
being cambered with the maximum camber forward of the 50 percent chord station, D. wherein said thickness is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is a forward camber located forward of the 30 percent chord station, and E. wherein said blade tip portion is of airfoil cross section defined by the coordinates:
Claim 93
Dependent Claim
67 words
being cambered with the maximum camber forward of the 50 percent chord station, D. wherein said thickness is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is a forward camber located forward of the 30 percent chord station, and E. wherein said blade tip portion is of airfoil cross section defined by the coordinates:
Claim 94
Dependent Claim
8 words
a thickness between 6 and 10 chord dimension,
Claim 95
Dependent Claim
8 words
a thickness between 6 and 10 chord dimension,
Claim 96
Dependent Claim
21 words
being forward cambered with the maximum camber of about 0.8 percent chord dimension and at about the 27 percent chord station.
Claim 97
Dependent Claim
21 words
being forward cambered with the maximum camber of about 0.8 percent chord dimension and at about the 27 percent chord station.
Claim 98
Dependent Claim
14 words
and being cambered with the maximum camber forward of the 50 percent chord station.
Claim 99
Dependent Claim
14 words
and being cambered with the maximum camber forward of the 50 percent chord station.
Claim 100
Dependent Claim
319 words
being cambered with the maximum camber forward of the 50 percent chord station, D. wherein said trapezoidal tip commences at a span station between 90 and 97 percent span and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent, + or - 15 percent, of the blade chord dimension and so that the tip center of pressure remains at the same chord station, E. wherein the thickness of said tip portion is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is a forward camber located forward of the 30 percent chord station, and F. wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c ( 1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = (x/c) < or = 1.0 ( yu/c t/c (6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5)yL/c t/c (-4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2(.01/.0952) leading edge radius lower: Rho L/c (t/c)2(.0066/.0952) where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leadiNg edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u and Rho L so calculated.
Claim 101
Dependent Claim
319 words
being cambered with the maximum camber forward of the 50 percent chord station, D. wherein said trapezoidal tip commences at a span station between 90 and 97 percent span and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent, + or - 15 percent, of the blade chord dimension and so that the tip center of pressure remains at the same chord station, E. wherein the thickness of said tip portion is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is a forward camber located forward of the 30 percent chord station, and F. wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c ( 1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = (x/c) < or = 1.0 ( yu/c t/c (6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5)yL/c t/c (-4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2(.01/.0952) leading edge radius lower: Rho L/c (t/c)2(.0066/.0952) where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leadiNg edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u and Rho L so calculated.
Claim 102
Dependent Claim
315 words
being cambered with th maximum camber forward of the 50 percent chord station, D. wherein said trapezoidal tip commences at a span station between 90 and 97 percent span and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent, + or - 15 percent, of the blade chord dimension and so that the tip center of pressure remains at the same chord station, E. wherein said thickness of about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is forward camber located forward of the 30 percent chord station, and F. wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c (1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = x/c < or = 1.0 ( yu/c t/c (6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5) yL/c t/c (-4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2(.01/.0952) leading edge radius lower: Rho L/c c (t/c)2(.0066/.0952) where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leading edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u and Rho L so calculated.
Claim 103
Dependent Claim
315 words
being cambered with th maximum camber forward of the 50 percent chord station, D. wherein said trapezoidal tip commences at a span station between 90 and 97 percent span and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent, + or - 15 percent, of the blade chord dimension and so that the tip center of pressure remains at the same chord station, E. wherein said thickness of about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is forward camber located forward of the 30 percent chord station, and F. wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c (1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = x/c < or = 1.0 ( yu/c t/c (6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5) yL/c t/c (-4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2(.01/.0952) leading edge radius lower: Rho L/c c (t/c)2(.0066/.0952) where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leading edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u and Rho L so calculated.
Claim 104
Dependent Claim
40 words
being cambered with the maximum camber forward of the 50 percent chord station, D. means to vary the position of the blade tip portion with respect to the remainder of the blade to thereby vary the blade tip portion twist.
Claim 105
Dependent Claim
40 words
being cambered with the maximum camber forward of the 50 percent chord station, D. means to vary the position of the blade tip portion with respect to the remainder of the blade to thereby vary the blade tip portion twist.
Claim 106
Dependent Claim
15 words
A blade according to claim 4 wherein said blade central portion twist is about -14*.
Claim 107
Dependent Claim
30 words
a rearwardly swept tip shaped to establish a tip lift vector offset from the blade elastic axis to produce a nose-up moment on the advancing blade during high speed flight.
Claim 108
Dependent Claim
30 words
a rearwardly swept tip shaped to establish a tip lift vector offset from the blade elastic axis to produce a nose-up moment on the advancing blade during high speed flight.
Claim 109
Dependent Claim
13 words
being cambered with the maximum camber forward of the 50 percent chord station.
Claim 110
Dependent Claim
13 words
being cambered with the maximum camber forward of the 50 percent chord station.
Claim 111
Dependent Claim
21 words
being forward cambered with the maximum camber of about 0.8 percent chord dimension and at about the 27 percent chord station.
Claim 112
Dependent Claim
21 words
being forward cambered with the maximum camber of about 0.8 percent chord dimension and at about the 27 percent chord station.
Claim 113
Dependent Claim
62 words
A blade according to claim 1 wherein said trapezoidal tip commences at a span station between 90 percent and 97 percent span and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent, + or - 15 percent, of the blade chord dimension and so that the tip center of pressure remains at the same chord station.
Claim 114
Dependent Claim
22 words
A blade according to claim 6 wherein the blade chord dimension is 26 inches and the tip chord dimension is 15.1 inches.
Claim 115
Dependent Claim
43 words
A blade according to claim 1 wherein said thickness is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 + or - 0.1 percent chord dimension and is a forward camber located forward of the 30 percent chord station.
Claim 116
Dependent Claim
215 words
A blade according to claim 1 wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c ( 1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = (x/c) < or = 1.0 ( yu/c t/c ( 6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5)yL/c t/c ( - 4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u /C (t/c)2(.01/.0952) leading edge radius lower: Rho L/C (t/c)2(.0066/.0952) where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leading edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u, Rho L so calculated.
Claim 117
Dependent Claim
20 words
A blade according to claim 1 wherein said blade tip portion is of airfoil cross section defined by the coordinates:
Claim 118
Dependent Claim
25 words
A blade according to claim 1 wherein the blade central portion thickness is 11 percent chord dimension and has a uniform twist of about -14*.
Claim 119
Dependent Claim
45 words
A blade according to claim 1 wherein the blade tip camber is maximum at about the blade 27 percent chord station and is shaped to produce a blade pitching moment coefficient within the range + or - .03 before moment divergence at subsonic Mach numbers.
Claim 120
Dependent Claim
180 words
A blade according to claim 2 wherein the blade tip portion sweep commences at about the blade 88 percent span station + or - 2 percent span for eight bladed rotors, at about the 87.5 percent span station + or - 2 percent span for seven bladed rotors, at about the 87 percent span station + or - 2 percent span for six bladed rotors, at about the 86 percent span station + or - 2 percent span for five bladed rotors, at about 84.5 span station + or - 2 percent span for four bladed rotors, at about the 82 percent span station + or - 2 percent span for three bladed rotors, at about the 77.5 percent span station + or - 2 percent span and extends to the blade tip for two bladed rotors, and at about the 71 percent span station + or - 2 percent span and extends to the blade tip for a one bladed rotor, and wherein the forward sweep and rearward sweep are of maximum angular sweep limits between 30* and 40*.
Claim 121
Dependent Claim
279 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion having a twist of -14* and having a thickness of about 11 percent chord dimension and connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion constituting the outer 29 percent of the blade span + or - 2 percent of the blade span in a one bladed rotor, constituting the outer 22.5 percent of the blade span + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have: 1. a generally negative non-linear twist of values ranging between -1* and about -8*,
Claim 122
Dependent Claim
279 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion having a twist of -14* and having a thickness of about 11 percent chord dimension and connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion constituting the outer 29 percent of the blade span + or - 2 percent of the blade span in a one bladed rotor, constituting the outer 22.5 percent of the blade span + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have: 1. a generally negative non-linear twist of values ranging between -1* and about -8*,
Claim 123
Dependent Claim
135 words
A helicopter blade having: A. a central portion with a twist of about 31 14*, and B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent for two bladed rotors, the outer 18 + or - 2 percent blade span for three bladed rotors, the outer 15.5 + or - 2 percent blade span for four bladed rotors, the outer 14 + or - 2 percent blade span for five bladed rotors, the outer 13 + or - 2 percent blade span for six bladed rotors, the outer 12.5 + or - 2 percent blade span for seven bladed rotors, and the outer 12 + or - 2 percent blade span for eight bladed rotors and having:
Claim 124
Dependent Claim
135 words
A helicopter blade having: A. a central portion with a twist of about 31 14*, and B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent for two bladed rotors, the outer 18 + or - 2 percent blade span for three bladed rotors, the outer 15.5 + or - 2 percent blade span for four bladed rotors, the outer 14 + or - 2 percent blade span for five bladed rotors, the outer 13 + or - 2 percent blade span for six bladed rotors, the outer 12.5 + or - 2 percent blade span for seven bladed rotors, and the outer 12 + or - 2 percent blade span for eight bladed rotors and having:
Claim 125
Dependent Claim
135 words
A helicopter blade having: A. a central portion with a twist of about -14*, and B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, the outer 18 + or - 2 percent blade span for three bladed rotors, the outer 15.5 + or - 2 percent blade span for four bladed rotors, the outer 14 + or - 2 blade span for five bladed rotors, the outer 13 + or - 2 percent blade span for six bladed rotors, the outer 12.5 + or - 2 percent blade span for seven bladed rotors, and the outer 12 + or - 2 percent blade span for eight bladed rotors nad having:
Claim 126
Dependent Claim
135 words
A helicopter blade having: A. a central portion with a twist of about -14*, and B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, the outer 18 + or - 2 percent blade span for three bladed rotors, the outer 15.5 + or - 2 percent blade span for four bladed rotors, the outer 14 + or - 2 blade span for five bladed rotors, the outer 13 + or - 2 percent blade span for six bladed rotors, the outer 12.5 + or - 2 percent blade span for seven bladed rotors, and the outer 12 + or - 2 percent blade span for eight bladed rotors nad having:
Claim 127
Dependent Claim
27 words
A blade according to claim 15 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 128
Dependent Claim
18 words
A blade according to claim 15 wherein said blade central portion has a twist of -20* or less.
Claim 129
Dependent Claim
57 words
A blade according to claim 15 wherein said trapezoidal tip commences at the span 95 percent station + or - 2 percent and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent of the blade chord dimension and so that the tip center of lift remains at the same chord station.
Claim 130
Dependent Claim
17 words
A blade according to claim 15 wherein the blade central portion thickness is 11 percent chord dimension.
Claim 131
Dependent Claim
29 words
A blade according to claim 15 wherein the blade camber is shaped to produce a blade pitching moment coefficient less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 132
Dependent Claim
14 words
A blade according to claim 1 wherein said tip portion is of constant planform.
Claim 133
Dependent Claim
26 words
A blade according to claim 22 and including means to cause said tip portion to be actuatable between a constant platform and a trapezoidal tip shape.
Claim 134
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade Central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 135
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade Central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 136
Dependent Claim
27 words
A blade according to claim 24 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 137
Dependent Claim
159 words
A blade according to claim 24 wherein said tip portion constituting the outer 29 percent of the blade span + or - 2 percent span in a one bladed rotor, constituting the outer 22.5 percent + or - 2 percent blade span for two bladed rotors, the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotors, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors.
Claim 138
Dependent Claim
212 words
A blade according to claim 24 wherein said blade central portion has a twist ranging from 0 to -20* and said generally non-linear tip twist commences at about the 71 percent span station + or - 2 percent span for one bladed rotors and extending to the blade tip, commences at about the 77.5 percent span station + or - 2 percent span for two bladed rotors, commences at about the 82 percent span station + or - 2 percent span for three bladed rotors and extends to the blade tip, commences at about the 85.5 percent span station + or - 2 percent span for four bladed rotors and extends to the blade tip, commences at about the 86 percent span station + or - 2 percent span for five bladed rotors and extends to the blade tip, commences at about the 87 percent span station + or - 2 percent span for six bladed rotors and extends to the blade tip, commences at about the 87.5 percent span station + or - 2 percent span for a seven bladed rotor and extends to the span tip, and commences at about the 88 percent span station + or -2 percent span for eight bladed rotors and extends to the blade tip.
Claim 139
Dependent Claim
13 words
A blade according to claim 27 wherein said twist is about -14 degrees.
Claim 140
Dependent Claim
39 words
A blade according to claim 24 wherein said thickness is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 percent chord dimension and is a forward camber located forward of the 30 percent chord station.
Claim 141
Dependent Claim
213 words
A blade according to claim 24 wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c (1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = (x/c) < or = 1.0 ( yu/c (t/c)( 6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5) yL/c t/c ( -4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2(.01/.0952) leading edge radius lower: Rho L/c (t/c)2(.0066/.0952) where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leading edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u and Rho L so calculated.
Claim 142
Dependent Claim
20 words
A blade according to claim 24 wherein said blade tip portion is of airfoil cross section defined by the coordinates:
Claim 143
Dependent Claim
29 words
A blade according to claim 24 wherein the blade central portion thickness ranges between 9-18 percent chord dimension and has a uniform twist equal to or less than 20*.
Claim 144
Dependent Claim
44 words
A blade according to claim 24 wherein the blade camber is maximum at about the blade 27 percent chord station and is shaped to produce a blade pitching moment coefficient within the range + or - 0.03 before moment divergence at subsonic Mach numbers.
Claim 145
Dependent Claim
39 words
A blade according to claim 25 wherein the blade tip portion sweep commences at about the blade 87 percent span station and wherein the forward sweep and rearward sweep are of maximum angular sweep limits between 30* and 40*.
Claim 146
Dependent Claim
241 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion having a twist less than 20* and connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion constituting about the outer 29 + or -2 percent blade span for one blaDed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 147
Dependent Claim
241 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion having a twist less than 20* and connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion constituting about the outer 29 + or -2 percent blade span for one blaDed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 148
Dependent Claim
42 words
A blade according to claim 35 wherein said tip is swept forward and then rearward and shaped and constructed to mass balance the tip so that the effective tip chordwise center of gravity is on or forward of the tip elastic axis.
Claim 149
Dependent Claim
193 words
A helicopter blade having: A. a central portion with a selected twist, B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 150
Dependent Claim
193 words
A helicopter blade having: A. a central portion with a selected twist, B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 151
Dependent Claim
193 words
A helicopter blade having: A. a central portion with a selected twist, B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 152
Dependent Claim
193 words
A helicopter blade having: A. a central portion with a selected twist, B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 153
Dependent Claim
27 words
A blade according to claim 37 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 154
Dependent Claim
181 words
A blade according to claim 37 wherein said blade central portion has a twist of -20* or less and said generally non-linear twist of the tip portion commences at about the 71 percent span station + or - 2 percent for one bladed rotors and extending to the blade tip, commences at about the 77.5 percent span station + or - 2 percent span for two bladed rotors, commences at about the 82 percent span station + or - 2 percent span for three bladed rotors, at about the 84.5 percent span station + or - 2 percent span for four bladed rotors, at about the 86 percent span station + or - 2 percent span for five bladed rotors, at about the 87 percent span station + or - 2 percent span for six bladed rotors, at about the 87.5 percent span station + or - 2 percent span for seven bladed rotors, and at about 88 percent span station + or - 2 percent span for eight bladed rotors and extending for all such blades to the blade tip.
Claim 155
Dependent Claim
17 words
A blade according to claim 37 wherein the blade central portion thickness is 11 percent chord dimension.
Claim 156
Dependent Claim
29 words
A blade according to claim 37 wherein the blade camber is shaped to produce a blade pitching moment coefficient less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 157
Dependent Claim
53 words
A blade according to claim 24 wherein said blade tip portion is rearwardly swept sufficiently to establish a lift vector or aerodynamic center at the blade tip which is offset from the blade tip elastic axis so as to produce a nose-up moment during forward flight mode of operation on the advancing blade.
Claim 158
Dependent Claim
40 words
A blade according to claim 25 wherein said blade tip portion is constructed so as to be mass balanced to establish the blade tip portion effective chordwise center of gravity on or slightly forward of the blade tip elastic axis.
Claim 159
Dependent Claim
24 words
A blade according to claim 44 wherein mass balance is accomplished by adding a selective balance weight in the region of blade forward sweep.
Claim 160
Dependent Claim
81 words
A blade according to claim 25 and wherein said blade tip portion is shaped and constructed so as to establish a lift vector or aerodynamic center of said tip portion offset from the tip portion elastic axis during high speed forward flight to produce a nose-up moment on the advancing blades and so as to be mass balanced to establish an effective tip chordwise center of gravity on or forward of the tip elastic axis and to produce minimum pitching moments.
Claim 161
Dependent Claim
29 words
A blade according to claim 24 and including means to actuate at least a portion of said blade tip portion between a non-swept position and a rearwardly swept position.
Claim 162
Dependent Claim
29 words
A blade according to claim 25 and including means to actuate at least a portion of said blade tip portion between a non-swEpt position and a rearwardly swept position.
Claim 163
Dependent Claim
14 words
A blade according to claim 24 wherein said tip portion is of constant planform.
Claim 164
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes or operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 165
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes or operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 166
Dependent Claim
155 words
A blade according to claim 50 wherein said tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of the blade span + or - 2 percent span for eight bladed rotors.
Claim 167
Dependent Claim
183 words
A blade according to claim 50 wherein said blade central portion has a twist ranging from 0 to -20* and said generally non-linear twist of the tip portion commences at about the 71 percent span station + or - 2 percent span for one bladed rotors and extending to the blade tip, commences at about the 77.5 percent span station + or - 2 percent span for two bladed rotors, commences at about the 82 percent span station + or - 2 percent span for three bladed rotors, at about the 84.5 percent span station + or - 2 percent span for four bladed rotors, at about the 86 percent span station + or - 2 percent span for five bladed rotors at about the 87 percent span station + or -2 percent span for six bladed rotors, at about the 87.5 percent span station + or - 2 percent span for seven bladed rotors, and at about the 88 percent span station + or - 2 percent span for eight bladed rotors, and extending for all such blades to the blade tip.
Claim 168
Dependent Claim
57 words
A blade according to claim 50 wherein said thickness is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 percent chord dimension and is a forward camber located forward of the 30 percent chord station to thereby produce low blade pitching moments without sacrificing higher maximum lift coefficient and drag divergence aerodynamic characteristics.
Claim 169
Dependent Claim
214 words
A blade according to claim 50 wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c (1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) - 2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) 25 < or = (x/c) < or = 1.0 ( yu/c t/c (6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5) yL/c t/c (-4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2 1.108 leading edge radius lower: Rho L/c (t/c)2 .7313 where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leading edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the values of Yu, YL, Rho u and Rho L so calculated.
Claim 170
Dependent Claim
18 words
A blade according to claim 50 wherein said blade tip portion is of airfoil cross section defined by
Claim 171
Dependent Claim
27 words
A blade according to claim 50 wherein the blade central portion thickness is between 9-18 percent chord dimension and has a uniform twist of 20* or less.
Claim 172
Dependent Claim
44 words
A blade according to claim 50 wherein the blade camber is maximum at about the blade 27 percent chord station and is shaped to produce a blade pitching moment coefficient within the range + or - .03 before moment divergence at subsonic Mach numbers.
Claim 173
Dependent Claim
14 words
A blade according to claim 50 wherein said tip portion is of constant planform.
Claim 174
Dependent Claim
193 words
A helicopter blade having: A. a central portion with a selected twist, B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade spaN + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 175
Dependent Claim
193 words
A helicopter blade having: A. a central portion with a selected twist, B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade spaN + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 176
Dependent Claim
195 words
A helicopter blade having: A. a central portion with a selected twist, and B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of the blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 177
Dependent Claim
195 words
A helicopter blade having: A. a central portion with a selected twist, and B. a tip portion constituting about the outer 29 + or - 2 percent blade span for one bladed rotors, the outer 22.5 + or - 2 percent blade span for two bladed rotors, constituting the outer 18 percent of the blade span + or - 2 percent span in a three bladed rotor, constituting the outer 15.5 percent of the blade span + or - 2 percent span for four bladed rotors, constituting the outer 14 percent of the blade span + or - 2 percent span for five bladed rotors, constituting the outer 13 percent of the blade span + or - 2 percent span for six bladed rotors, constituting the outer 12.5 percent of the blade span + or - 2 percent span for seven bladed rotors, and constituting the outer 12 percent of blade span + or - 2 percent span for eight bladed rotors and connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 178
Dependent Claim
29 words
A blade according to claim 59 wherein the blade camber is shaped to produce a blade pitching moment coefficient less than 0.03 before amount divergence at subsonic Mach numbers.
Claim 179
Dependent Claim
91 words
A blade according to claim 60 wherein said airfoil cross section is chaped to produce a maximum lift coefficient, CL max., of at least 1.41 and 1.0 at tip Mach numbers of 0.3 and 0.6, respectively, and a drag divergence Mach number of at least 0.76 at a lift coefficient of 0.2 and wherein the blade camber is maximum at about the blade 27 percent chord station and is shaped to produce a blade pitching moment coefficient within the range + or - .03 before moment divergence at subsonic Mach numbers.
Claim 180
Dependent Claim
397 words
A blade according to claim 1 and having solidity of 0.115 wherein said blade tip portion twist is -4.67* at the 100 percent blade span station, with a tolerance of +3* and -1* twist and a tolerance of + or - 2 percent span for the span station for blades used with rotors having between one and eight blades; is -4.67* at the 71 percent span station for one bladed rotors, at the 77.5 percent span station for two bladed rotors, the 90 percent blade span station for three bladed rotors, at the 92.5 percent blade span station for four bladed rotors, at the 94 percent blade span station for five bladed rotors, at the 95 percent blade span station for six bladed rotors, at the 95.5 percent blade span station for seven bladed rotors, and at the 96 percent blade span station for eight bladed rotors, and havinG + or - 2* twist tolerance and + or - 2 percent span station tolerance; is -2.62* at the 74.5 percent blade span station for one bladed rotors, at the 80.5 percent blade span station for two bladed rotors, at the 84.5 percent blade span station for three bladed rotors, at the 87 percent blade span station for four bladed rotors, at the 88.5 percent blade span station for five bladed rotors, at the 89.5 percent blade span station for six bladed rotors, at the 90 percent blade span station for seven bladed rotors and at the 90.5 percent blade span station for eight bladed rotors, and having twist tolerance between +3* and -.5*, and a span station tolerance of + or - 2 percent span; and -1.2 degrees at the 71 percent blade span station for one bladed rotors, at the 77.5 percent blade span station for two bladed rotors, at the 82 percent blade span station for three bladed rotors, at the 84.5 percent blade span station for four bladed rotors, at the 86 percent blade span station for five bladed rotors, at the 87 percent blade span station for six bladed rotors, at the 87.5 percent blade span station for seven bladed rotors, and at the 88 percent blade span station for eight bladed rotors, and with a twist tolerance of + or - 1* and a span station tolerance of + or - 2 percent span, and varies substantially linearly between these span stations.
Claim 181
Dependent Claim
397 words
A blade according to claim 24 and having solidity of .115 wherein said blade tip portion twist is -4.67* at the 100 percent blade span station, with a tolerance of +3* and -1* twist and a tolerance of + or - 2 percent span for the span station for blades used with rotors having between one and eight blades; is -4.67* at the 71 percent span station for one bladed rotors, at the 77.5 percent span station for two bladed rotors, at the 90 percent blade span station for three bladed rotors, at the 92.5 percent blade span station for four bladed rotors, at the 94 percent blade span station for five bladed rotors, at the 95 percent blade span station for six bladed rotors, at the 95.5 percent blade span station for seven bladed rotors, and at the 96 percent blade span station for eight bladed rotors, and having + or - 2* twist tolerance and + or - 2 percent span station tolerance; is -2.62* at the 74.5 percent blade span station for one bladed rotors, at the 80.5 percent blade span station for two bladed rotors, at the 84.5 percent blade span station for three bladed rotors, at the 87 percent blade span station for four bladed rotors, at the 88.5 percent blade span station for five bladed rotors, at the 89.5 percent blade span station for six bladed rotors, at the 90 percent blade span station for seven bladed rotors and at the 90.5 percent blade span station for eight bladed rotors, and having twist tolerance between +3* and -.5*, and a span station tolerance of + or - 2 percent span; and -1.2* at the 71 percent blade span station for one bladed rotors, at the 77.5 percent blade span station for two bladed rotors, at the 82 percent blade span station for three bladed rotors, at the 84.5 percent blade span station for four bladed rotors, at the 86 percent blade span station for five bladed rotors, at the 87 percent blade span station for six bladed rotors, at the 87.5 percent blade span station for seven bladed rotors, and at the 88 percent blade span station for eight bladed rotors, and with a twist tolerance of + or - 1* and a span station tolerance of + or - 2 percent span and varies substantially linearly between these span stations.
Claim 182
Dependent Claim
397 words
A blade accorDing to claim 50 and having solidity of .115 wherein said blade tip portion twist is -4.67* at the 100 percent blade span station, with a tolerance of +3* and -1* twist and a tolerance of + or - 2 percent span for the span station for blades used with rotors having between one and eight blades; is -4.67* at the 71 percent span station for one bladed rotors, at the 77.5 percent span station for two bladed rotors, at the 90 percent blade span station for three bladed rotors, at the 92.5 percent blade span station for four bladed rotors, at the 94 percent blade span station for five bladed rotors, at the 95 percent blade span station for six bladed rotors, at the 95.5 percent blade span station for seven bladed rotors, and at the 96 percent blade span station for eight bladed rotors, and having + or - 2* twist tolerance and + or - 2 percent span station tolerance; is -2.62* at the 74.5 percent blade span station for one bladed rotors, at the 80.5 percent blade span station for two bladed rotors, at the 84.5 percent blade span station for three bladed rotors, at the 87 percent blade span station for four bladed rotors, at the 88.5 percent blade span station for five bladed rotors, at the 89.5 percent blade span station for six bladed rotors, at the 90 percent blade span station for seven bladed rotors, and at the 90.5 percent blade span station for eight bladed rotors, and having twist tolerance between +3* and -.5*, and a span station tolerance of + or - 2 percent span; and -1.2* at the 71 percent blade span station for one bladed rotors, at the 77.5 percent blade span station for two bladed rotors, at the 82 percent blade span station for three bladed rotors, at the 84.5 percent blade span station for four bladed rotors, at the 86 percent blade span station for five bladed rotors, at the 87 percent blade span station for six bladed rotors, at the 87.5 percent blade span station for seven bladed rotors, and at the 88 percent blade span station for eight bladed rotors, and with a twist tolerance of + or - 1* and a span station tolerance of + or - 2 percent span and varies substantially linearly between these span stations.
Claim 183
Dependent Claim
254 words
A blade according to claim 1 having a solidity equal to .115 wherein said blade tip portion twist is equal to: the blade basic twist -1.83* at the 100 percent span station for blades used with one to eight bladed rotors, and with a tolerance of +3* and -1*; the blade basic twist -2.33* at the 80 percent span station for one bladed rotors, at the 85.5 percent span station for two bladed rotors, at the 90 percent span station for three bladed rotors, at the 92.5 percent span station for four bladed rotors, at the 94 percent span station for five bladed rotors, at the 95 percent span station for six bladed rotors, at the 95.5 percent span station for seven bladed rotors, and at the 96 percent span station for eight bladed rotors, with a twist tolerance of +2* and -1*; the blade basic twist -1.2*, at the 74.5 percent blade span station for one bladed rotors, at the 80.5 percent blade span station for two bladed rotors, at the 84.5 percent span station for three bladed rotors, at the 87 percent span station for four bladed rotors, at the 88.5 percent span station for five bladed rotors, at the 89.5 percent span station for six bladed rotors, at the 90 percent span station for seven bladed rotors, and at the 90.5 percent span station for eight bladed rotors, with a twist tolerance of +3* and -.5*; and the blade basic twist at the 87 percenT span station, + or - 1*.
Claim 184
Dependent Claim
254 words
A blade according to claim 24 having a solidity equal to .115 wherein said blade tip portion twist is equal to: the blade basic twist -1.83* at the 100 percent span station for blades used with one to eight bladed rotors, and with a tolerance of +3* and -1*; the blade basic twist -2.33* at the 80 percent span station for one bladed rotors, at the 85.5 percent span station for two bladed rotors, at the 90 percent span station for three bladed rotors, at the 92.5 percent span station for four bladed rotors, at the 94 percent span station for five bladed rotors, at the 95 percent span station for six bladed rotors, at the 95.5 percent span station for seven bladed rotors, and at the 96 percent span station for eight bladed rotors, with a twist tolerance of +2* and -1*; the blade basic twist -1.2*, at the 74.5 percent blade span station for one bladed rotors, at the 80.5 percent blade span station for two bladed rotors, at the 84.5 percent span station for three bladed rotors, at the 87 percent span station for four bladed rotors, at the 88.5 percent span station for five bladed rotors, at the 89.5 percent span station for six bladed rotors, at the 90 percent span station for seven bladed rotors, and at the 90.5 percent span station for eight bladed rotors, with a twist tolerance of +3* and -.5*; and the blade basic twist at the 87 percent span station, + or - 1*.
Claim 185
Dependent Claim
253 words
A blade according to claim 50 having a solidity equal to .115 wherein said blade tip portion twist is equal to: the blade basic twist -1.83* at the 100 percent span station for blades used with one to eight bladed rotors, and with a tolerance of +3* and -1*; the blade basic twist -2.33* at the 80 percent span station for one bladed rotors, at the 85.5 percent span station for two bladed rotors, at the 90 percent span station for three bladed rotors, at the 92.5 percent span station for four bladed rotors, at the 94 percent span station for five bladed rotors, at the 95 percent span station for six bladed rotors, at the 95.5 percent span station for seven bladed rotors, and at the 96 percent span station for eight bladed rotors, with twist tolerance of +2* and -1*; the blade basic twist -1.2*, at the 74.5 percent blade span station for one bladed rotors, at the 80.5 percent blade span station for two bladed rotors, at the 84.5 percent span station for three bladed rotors, at the 87 percent span station for four bladed rotors, at the 88.5 percent span station for five bladed rotors, at the 89.5 percent span station for six bladed rotors, at the 90 percent span station for seven bladed rotors, and at the 90.5 percent span station for eight bladed rotors, with a twist tolerance of +3* and -.5*; and the blade basic twist at the 87 percent span station, + or - 1*.
Claim 186
Dependent Claim
86 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade central portion to define the blade span and shaped to have:
Claim 187
Dependent Claim
86 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade central portion to define the blade span and shaped to have:
Claim 188
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 189
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 190
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 191
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 192
Independent Claim
93 words
The method of improving helicopter rotor performance comprising selectively twisting the blade tip to reduce blade tip loading in hover operation, and selectively applying sweep to the blade tip to produce a tip aerodynamic center aft of the blade elastic axis to generate dynamic twist to thereby: A. reduce tip twist and hence reduce tip loading on the advancing blade in high speed flight, B. increase tip twist and hence reduce tip loading on the retreating blade in high speed flight, and C. increase blade twist and hence reduce tip loading in hover.
Claim 193
Independent Claim
93 words
The method of improving helicopter rotor performance comprising selectively twisting the blade tip to reduce blade tip loading in hover operation, and selectively applying sweep to the blade tip to produce a tip aerodynamic center aft of the blade elastic axis to generate dynamic twist to thereby: A. reduce tip twist and hence reduce tip loading on the advancing blade in high speed flight, B. increase tip twist and hence reduce tip loading on the retreating blade in high speed flight, and C. increase blade twist and hence reduce tip loading in hover.
Claim 194
Dependent Claim
85 words
Apparatus according to claim 1 wherein said blade tip portion has an airfoil cross-sectional shape with two dimensional aerodynamic characteristics such that at tip Mach numbers of 0.3 and 0.6, the maximum lift coefficient, CL max., is at least 1.41 and 1, respectively, and has a drag divergence Mach number of at leasT 0.76 at a lift coefficient of 0.2, and wherein the blade camber is shaped to produce a blade pitching moment coefficient of less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 195
Dependent Claim
85 words
Apparatus according to claim 24 wherein said blade tip portion has an airfoil cross-sectional shape with two dimensional aerodynamic characteristics such that at tip Mach numbers of 0.3 and 0.6, the maximum lift coefficient, CL max., is at least 1.41 and 1, respectively, and has a drag divergence Mach number of at least 0.76 at a lift coefficient of 0.2, and wherein the blade camber is shaped to produce a blade pitching moment coefficient of less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 196
Dependent Claim
85 words
Apparatus according to claim 50 wherein said blade tip portion has an airfoil cross-sectional shape with two dimensional aerodynamic characteristics such that at tip Mach numbers of 0.3 and 0.6, the maximum lift coefficient, CL max., is at least 1.41 and 1, respectively, and has a drag divergence Mach number of at least 0.76 at a lift coefficient of 0.2, and wherein the blade camber is shaped to produce a blade pitching moment coefficient of less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 197
Dependent Claim
115 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span, and D. means to vary the position of the blade tip portion with respect to the remainder of the blade to thereby vary the blade tip portion twist.
Claim 198
Dependent Claim
115 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span, and D. means to vary the position of the blade tip portion with respect to the remainder of the blade to thereby vary the blade tip portion twist.
Claim 199
Dependent Claim
32 words
A helicopter blade according to claim 76 wherein the blade tip portion twist is varied to be maximum at high rotor thrust operation and to be minimum at low rotor thrust operation.
Claim 200
Dependent Claim
40 words
A helicopter blade according to claim 77 wherein the twist of the blade tip portion is varied cyclically so that the advancing blade is operated at very close to zero angle of attack and retreating blade is operated below stall.
Claim 201
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 202
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 203
Dependent Claim
71 words
A helicopter blade according to claim 14 wherein said blade central portion has a twist of about -14* and a thickness of from 95 percent to 18 percent chord dimension, and an airfoil cross section incorporating moderate forward camber with maximum camber forward of the blade 50 percent chord line, and shaped and fabricated to have a locus of airfoil section aerodynamic cenTers displaced rearward of the blade structural elastic axis.
Claim 204
Dependent Claim
20 words
A helicopter blade according to claim 14 wherein said central portion is of airfoil cross section defined by the coordinates:
Claim 205
Dependent Claim
68 words
A helicopter blade according to claim 15 wherein said central portion has a twist of about -14* a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 206
Dependent Claim
20 words
A helicopter blade according to claim 15 wherein said central portion is of airfoil cross section defined by the coordinates:
Claim 207
Dependent Claim
27 words
A blade according to claim 82 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 208
Dependent Claim
57 words
A blade according to claim 82 wherein said trapezoidal tip commences at the span 95 percent stAtion + or - 2 percent and reduces uniformly in chord dimension so that the blade tip chord is about 60 percent of the blade chord dimension and so that the tip center of lift remains at the same chord station.
Claim 209
Dependent Claim
14 words
A blade according to claim 82 wherein said tip portion is of constant planform.
Claim 210
Dependent Claim
26 words
A blade according to claim 86 and including means to cause said tip portion to be actuatable between a constant planform and a trapezoidal tip shape.
Claim 211
Dependent Claim
109 words
A blade according to claim 82 and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span, and D. means to vary the position of the blade tip portion with respect to the remainder of the blade to thereby vary the blade tip portion twist.
Claim 212
Dependent Claim
109 words
A blade according to claim 83 and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span, and D. means to vary the position of the blade tip portion with respect to the remainder of the blade to thereby vary the blade tip portion twist.
Claim 213
Dependent Claim
69 words
A helicopter blade according to claim 24 wherein said central portion has a twist of about -14*, a thickness of from 9 percent to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 214
Dependent Claim
27 words
A blade according to claim 90 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 215
Dependent Claim
167 words
A blade according to claim 90 wherein said blade central portion has a twist ranging from 0*to -20* and said generally non-linear tip twist commences at about the 88 percent span station + or - 2 percent span for eight bladed rotors, at about the 87.5 percent span station + or - 2 percent span for seven bladed rotors, at about the 87 percent span station + or - 2 percent span for six bladed rotors, at about the 86 percent span station + or - 2 percent span for five bladed rotors, at about 84.5 percent span station + or - 2 percent span for four bladed rotors, at about the 82 percent span station + or - 2 percent span for three bladed rotors, at about the 77.5 percent blade span station + or - 2 span for two bladed rotors, at about the 71 percent blade span station + or - 2 percent span for one bladed rotors, and extending to the blade tip.
Claim 216
Dependent Claim
20 words
A helicopter blade according to claim 24 wherein said central portion is of airfoil cross section defined by the coordinates:
Claim 217
Dependent Claim
12 words
A blade according to claim 93 wherein said twist is about -14*.
Claim 218
Dependent Claim
43 words
A blade according to claim 90 wherein said thickness of said tip section is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 percent chord dimension and is a forward camber located forward of the 30 percent chord station.
Claim 219
Dependent Claim
20 words
A blade according to claim 90 wherein said blade tip portion is of airfoil cross section defined by the formula:
Claim 220
Dependent Claim
20 words
A blade according to claim 90 wherein said blade tip portion is of airfoil cross section defined by the coordinates:
Claim 221
Dependent Claim
49 words
A blade according to claim 90 wherein the blade central portion and tip portion camber is mAximum at about the blade 27 percent chord station and is shaped to produce a blade pitching moment coefficient within the range + or - .03 before moment divergence at subsonic Mach numbers.
Claim 222
Dependent Claim
172 words
A blade according to claim 90 wherein the blade tip portion sweep commences at about the 88 percent span station + or - 2 percent span for eight bladed rotors, at about the 87.5 percent span station + or - 2 percent span for seven bladed rotors, at about the 87 percent span station + or - 2 percent span for six bladed rotors, at about the 86 percent span station + or - 2 percent span for five bladed rotors, at about 84.5 percent span station + or - 2 percent for four bladed rotors, and at about the 82 percent span station + or - 2 percent span for three bladed rotors, at about the 77.5 percent blade span station + or - 2 percent for two bladed rotors, at about the 71 percent blade span station + or - 2 percent for one bladed rotors, and extending to the blade tip, and wherein the forward sweep and rearward sweep are of maximum angular sweep limits between 30* and 40*.
Claim 223
Dependent Claim
68 words
A helicopter blade according to claim 35 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 224
Dependent Claim
42 words
A blade according to claim 100 wherein said tip is swept forward and then rearward and shaped and constructed to mass balance the tip so that the effective tip chordwise center of gravity is on or forward of the tip elastic axis.
Claim 225
Dependent Claim
67 words
A helicopter blade according to claim 37 wherein central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 226
Dependent Claim
68 words
A helicopter blade according to claim 38 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 227
Dependent Claim
27 words
A blade according to claim 102 wherein said tip portion is swept forward at a blade span inboard station and rearward at a blade span outboard station.
Claim 228
Dependent Claim
165 words
A blade according to claim 102 wherein said blade central portion has a twist of -20* or less and said generally non-linear twist commences at about the 88 percent span station + or - 2 percent span for eight bladed rotors, at about the 87.5 percent span station + or - 27 percent span for seven bladed rotors, at about the 87 percent span station + or - 2 percent span for six bladed rotors, at about the 86 percent span station + or - 2 percent span for five bladed rotors, at about 84.5 percent span station + or - 2 percent span for four bladed rotors, at about the 82 percent span station + or - 2 percent span for three bladed rotors, at about the 77.5 percent blade span station + or - 2 percent span for two bladed rotors, at about the 71 percent span station + or - 2 span for one bladed rotors, and extending to the blade tip.
Claim 229
Dependent Claim
53 words
A blade according to claim 90 wherein said blade tip portion is rearwardly swept sufficiently to establish a lift vector or aerodynamic center at the blade tip which is oFfset from the blade tip elastic axis so as to produce a nose-up moment during forward flight mode of operation on the advancing blade.
Claim 230
Dependent Claim
40 words
A blade according to claim 90 wherein said blade tip portion is constructed to as to be mass balanced to establish the blade tip portion effective chordwise center of gravity on or slightly forward of the blade tip elastic axis.
Claim 231
Dependent Claim
24 words
A blade according to claim 91 wherein mass balance is accomplished by adding a selective balance weight in the region of blade forward sweep.
Claim 232
Dependent Claim
81 words
A blade according to claim 90 and wherein said blade tip portion is shaped and constructed so as to establish a lift vector or aerodynamic center of said tip portion offset from the tip portion elastic axis during high speed forward flight to produce a nose-up moment on the advancing blades and so as to be mass balanced to establish an effective tip chordwise center of gravity on or forward of the tip elastic axis and to produce minimum pitching moments.
Claim 233
Dependent Claim
29 words
A blade according to claim 90 and including means to actuate at least a portion of said blade tip portion between a non-swept position and a rearwardly swept position.
Claim 234
Dependent Claim
29 words
A blade according to claim 90 and including means to actuate at least a portion of said blade tip portion between a non-swept position and a rearwardly swept position.
Claim 235
Dependent Claim
14 words
A blade according to claim 90 wherein said tip portion is of constant planform.
Claim 236
Dependent Claim
68 words
A helicopter blade according to claim 50 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 237
Dependent Claim
59 words
A blade according to claim 113 wherein said tip portion thickness is about 9.5 percent chord dimension and wherein said maximum camber is about 0.8 percent chord dimension and is a forward camber located forward of the 30 percent chord station to thereby produce low blade pitching moments without sacrificing higher maximum lift coefficient and drag divergence aerodynamic characteristics.
Claim 238
Dependent Claim
212 words
A blade according to claim 113 wherein said blade tip portion is of airfoil cross section defined by the formula: 0 < or = (x/c) < or = .25 ( yu/c t/c (1.307 Square Root (x/c) + 3.767(x/c) - 46.7(x/c)2 + 201.3(x/c)3 - 316.8(x/c)4) yL/c t/c (-1.162 Square Root (x/c) -2.256(x/c) + 37.2(x/c)2 -170.2(x/c)3 + 272.9(x/c)4) .25 < or = (x/c) < or = 1.0 ( yu/c t/c (6.6134(x/c) -28.04(x/c)2 + 56.42(x/c)3 - 56(x/c)4 + 21.15(x/c)5)yL/c t/c (-4.7661(x/c) + 20.53(x/c)2 - 41.92(x/c)3 + 42(x/c)4 -16(x/c)5) where X is a chord station measured from 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 X and where the leading edge radii can be defined by the following equations: leading edge radius upper: Rho u/c (t/c)2 1.108 leading edge radius lower: Rho L/c (t/c)2 .7313 where Rho u is the leading edge radius of the blade upper airfoil and Rho L is the leading edge radius of the lower blade airfoil, both taken from a point on the blade chord, and within a range of + or - 3 percent of the valuEs of Yu, YL, Rho u and Rho L so calculated.
Claim 239
Dependent Claim
20 words
A blade according to claim 113 wherein said blade tip portion is of airfoil cross section defined by the coordinates:
Claim 240
Dependent Claim
68 words
A helicopter blade according to claim 59 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 241
Dependent Claim
93 words
A blade according to claim 113 wherein said tip portion airfoil cross section is shaped to produce a maximum lift coefficient, CL max., of at least 1.41 and 1.0 at tip Mach numbers of 0.3 and 0.6, respectively, and a drag divergence Mach number of at least 0.76 at a lift coefficient of 0.2 and wherein the blade camber is maximum at about the blade 27 percent chord station and is shaped to produce a blade pitching moment coefficient within the range + or - .03 before moment divergence at subsonic Mach numbers.
Claim 242
Dependent Claim
67 words
Ahelicopter blade according to claim 63 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 243
Dependent Claim
68 words
A helicopter blade according to claim 64 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 244
Dependent Claim
68 words
A helicopter blade according to claim 65 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 245
Dependent Claim
68 words
A helicopter blade according to claim 66 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 246
Dependent Claim
67 words
A helicopter blade according to claim 67 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 247
Dependent Claim
68 words
A helicopter blade according to claim 68 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 248
Dependent Claim
68 words
A helicopter blade according to claim 69 wherein aid central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 249
Dependent Claim
68 words
A helicoter blade according to claim 70 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 250
Dependent Claim
68 words
A helicopter blade according to claim 71 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 251
Dependent Claim
56 words
The method according to claim 72 and including the additional step of fabricating the blade so that its airfoil section has positive camber throughout and with maximum camber forward of the 50 percent span station, and so that the locus of blade aerodynamic centers throughout the blade airfoil section is aft of the blade elastic axis.
Claim 252
Dependent Claim
85 words
Apparatus according to claim 80 wherein said blade tip portion has an airfoil cross-sectional shape with two dimensional aerodynamic characteristics such that at tip Mach numbers f 0.3 and 0.6, the maximum lift coefficient, CL max., is at least 1.41 and 1, respectively, and has a drag divergence Mach number of at least 0.76 at a lift coefficient of 0.2, and wherein the blade camber is shaped to produce a blade pitching moment coefficient of less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 253
Dependent Claim
85 words
Apparatus according to claim 90 wherein said blade tip portion has an airfoil cross-sectional shape with two dimensional aerodynamic characteristics such that at tip Mach numbers of 0.3 and 0.6, the maximum lift coefficient, CL max., is at least 1.41 and 1, respectively, and has a drag divErgence Mach number of at least 0.76 at a lift coefficient of 0.2, and wherein the blade camber is shaped to produce a blade itching moment coefficient of less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 254
Dependent Claim
85 words
Apparatus according to claim 113 wherein said blade tip portion has an airfoil cross-sectional shape with two dimensional aerodynamic characteristics such that at tip Mach numbers of 0.3 and 0.6, the maximum lift coefficient, CL max., is at least 1.41 and 1, respectively, and has a drag divergence Mach number of at least 0.76 at a lift coefficient of 0.2, and wherein the blade camber is shaped to produce a blade pitching moment coefficient of less than 0.03 before moment divergence at subsonic Mach numbers.
Claim 255
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation thereiwth in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 256
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation thereiwth in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 257
Dependent Claim
68 words
A helicopter blade according to claim 132 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 258
Dependent Claim
91 words
A helicopter blade having a span dimension a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 259
Dependent Claim
91 words
A helicopter blade having a span dimension a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 260
Dependent Claim
68 words
A helicopter blade according to claim 134 wherein said central portion has a twist of about -14*, a thickness of from 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum center located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 261
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 262
Dependent Claim
91 words
A helicopter blade having a span dimension, a chord dimension, a tip and including: A. a blade root section adapted to be connected to a rotor hub for rotation therewith in both hover and forward flight modes of operation, B. a blade central portion connected to said blade root portion and extending outwardly therefrom, C. a blade tip portion connected to said central portion and constituting the blade outer extremity and cooperating with said blade root portion and said blade central portion to define the blade span and shaped to have:
Claim 263
Dependent Claim
68 words
A helicopter blade according to claim 136 wherein said central portion has a twist of about -14*, a thickness of rom 9 to 18 percent chord dimension, an airfoil cross section having positive camber with the maximum camber located forward of the 50 percent chord station, and being shaped and fabricated to have the locus of airfoil section aerodynamic centers displaced rearward of the blade structural elastic axis.
Claim 264
Dependent Claim
20 words
A helicopter blade according to claim 137 wherein said central portion is of airfoil cross section defined by the coordinates:
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-01 | 1977-12-31 | 1978-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-01 | 1981-12-31 | 1982-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-01 | 1985-12-31 | 1986-07-02 | $7700.00 | Window Closed / Lapsed |