US3713751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aerodynamic blade with high stiffness-to-weight ratio
Assignee: RTX Corp
•
Filing: 1970-10-29
•
Granted: 1973-01-30
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Expires: 1990-10-29
Abstract
Abstract A flight blade or wing having a structural spar at its forward end comprising a solid forward-portion and an after-portion of low density construction, such as a sandwich construction of honeycomb, plastic foam, or balsa wood core and having a structural trailing edge pocket member to produce a blade of maximum stiffness and minimum weight by eliminating leading edge counterweights and reducing spar weight by substituting sandwich construction material for solid metal wall members in the spar after portion.
Inventors
- 👤 E Fradenburgh
- 👤 E Kiely
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:33
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/46; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24149
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
190 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade span and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having: 1. a forward-portion fabricated of solid metal and being of Cshaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft; 2. an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises: a. an outer skin, b. an inner skin, c. and a low density core extending between and connected to said skins; B. a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate With said spar to define the blade crosssectional shape.
Claim 2
Dependent Claim
190 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade span and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having: 1. a forward-portion fabricated of solid metal and being of Cshaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft; 2. an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises: a. an outer skin, b. an inner skin, c. and a low density core extending between and connected to said skins; B. a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate With said spar to define the blade crosssectional shape.
Claim 3
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade span and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 4
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade span and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 5
Dependent Claim
37 words
a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft;
Claim 6
Dependent Claim
37 words
a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft;
Claim 7
Dependent Claim
95 words
a hollow structural spar of D-shaped cross section extending along the blade span and having: a. a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft, b. an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises:
Claim 8
Dependent Claim
95 words
a hollow structural spar of D-shaped cross section extending along the blade span and having: a. a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft, b. an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises:
Claim 9
Dependent Claim
3 words
an outer skin,
Claim 10
Dependent Claim
3 words
an outer skin,
Claim 11
Dependent Claim
37 words
a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft,
Claim 12
Dependent Claim
37 words
a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of the C extend aft,
Claim 13
Dependent Claim
36 words
a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of C extend aft,
Claim 14
Dependent Claim
36 words
a forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of C extend aft,
Claim 15
Dependent Claim
3 words
an outer skin,
Claim 16
Dependent Claim
3 words
an outer skin,
Claim 17
Dependent Claim
3 words
an outer skin,
Claim 18
Dependent Claim
3 words
an outer skin,
Claim 19
Dependent Claim
36 words
A forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of C extend aft,
Claim 20
Dependent Claim
36 words
A forward-portion fabricated of solid metal and being of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of C extend aft,
Claim 21
Dependent Claim
3 words
an inner skin,
Claim 22
Dependent Claim
3 words
an inner skin,
Claim 23
Dependent Claim
3 words
an inner skin,
Claim 24
Dependent Claim
3 words
an inner skin,
Claim 25
Dependent Claim
55 words
a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape, and C. means to cause said movable blade portion to move relative to said fixed blade portion so as to vary blade length.
Claim 26
Dependent Claim
55 words
a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape, and C. means to cause said movable blade portion to move relative to said fixed blade portion so as to vary blade length.
Claim 27
Dependent Claim
3 words
an inner skin,
Claim 28
Dependent Claim
3 words
an inner skin,
Claim 29
Dependent Claim
95 words
an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises: a. an outer skin, b. an inner skin, c. and a low density core extending between and connected to said skins; B. a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate With said spar to define the blade cross-sectional shape.
Claim 30
Dependent Claim
95 words
an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises: a. an outer skin, b. an inner skin, c. and a low density core extending between and connected to said skins; B. a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate With said spar to define the blade cross-sectional shape.
Claim 31
Dependent Claim
12 words
Apparatus according to claim 1 wherein said core is of honeycomb construction.
Claim 32
Dependent Claim
101 words
an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises: a. an outer skin, b. an inner skin, c. and a low density core extending between and connected to said skins; B. a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape and being of sandwich construction including:
Claim 33
Dependent Claim
101 words
an after-portion comprising a wall of sandwich construction and being of channel-shaped cross section and of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section and which wall comprises: a. an outer skin, b. an inner skin, c. and a low density core extending between and connected to said skins; B. a structural pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape and being of sandwich construction including:
Claim 34
Dependent Claim
122 words
an after-portion of channnel-shaped cross section fabricated to be of lower density than the spar forward portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section, B. a pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape, and wherein said blade spar includes: A. a root portion of D-shaped cross section with solid metal walls and defining the spar forward-portion and the spar after-portion at the spar root, and B. a tip portion of D-shaped cross section with solid metal walls and defining the spar forward-portion and the spar after portion at the spar tip.
Claim 35
Dependent Claim
122 words
an after-portion of channnel-shaped cross section fabricated to be of lower density than the spar forward portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section, B. a pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape, and wherein said blade spar includes: A. a root portion of D-shaped cross section with solid metal walls and defining the spar forward-portion and the spar after-portion at the spar root, and B. a tip portion of D-shaped cross section with solid metal walls and defining the spar forward-portion and the spar after portion at the spar tip.
Claim 36
Dependent Claim
94 words
an after-portion of channel-shaped cross section fabricated to be of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section, B. a pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape, and wherein said blade spar includes: A. a root portion of D-shaped cross section with solid metal walls and defining the spar forward-portion and the spar after-portion at the spar root.
Claim 37
Dependent Claim
94 words
an after-portion of channel-shaped cross section fabricated to be of lower density than the spar forward-portion and connected thereto to cooperate therewith in defining a hollow spar of D-shaped cross section, B. a pocket member positioned aft of said spar and connected thereto and shaped to define the blade trailing edge and to cooperate with said spar to define the blade cross-sectional shape, and wherein said blade spar includes: A. a root portion of D-shaped cross section with solid metal walls and defining the spar forward-portion and the spar after-portion at the spar root.
Claim 38
Dependent Claim
11 words
Apparatus according to claim 1 wherein said core is plastic foam.
Claim 39
Dependent Claim
11 words
a tapered honeycomb core extending between and connected to said skins.
Claim 40
Dependent Claim
11 words
a tapered honeycomb core extending between and connected to said skins.
Claim 41
Dependent Claim
12 words
and a low density core extending between and connected to said skins,
Claim 42
Dependent Claim
12 words
and a low density core extending between and connected to said skins,
Claim 43
Dependent Claim
123 words
lightweight core material extending between and connected to said inner and outer skin, and C. wherein said spar forward-portion is of selected wall thickness and of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of C extend aft therefrom and, further, wherein the spar after-portion is of substantially the same wall thickness as said wall thickness of said forward-portion and is of channel-shaped cross section with the legs of the channel connected directly to the legs of the spar forward-portion to form a smooth continuation thereof so that the spar forward and after-portions cooperate to define a hollow spar of D-shaped cross section and substantially constant wall thickness.
Claim 44
Dependent Claim
123 words
lightweight core material extending between and connected to said inner and outer skin, and C. wherein said spar forward-portion is of selected wall thickness and of C-shaped cross section and positioned so that the curved portion of the C defines the blade leading edge and so that the legs of C extend aft therefrom and, further, wherein the spar after-portion is of substantially the same wall thickness as said wall thickness of said forward-portion and is of channel-shaped cross section with the legs of the channel connected directly to the legs of the spar forward-portion to form a smooth continuation thereof so that the spar forward and after-portions cooperate to define a hollow spar of D-shaped cross section and substantially constant wall thickness.
Claim 45
Dependent Claim
13 words
Apparatus according to claim 1 wherein said core is fabricated from balsa wood.
Claim 46
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade span and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 47
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade span and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 48
Dependent Claim
39 words
Apparatus according to claim 5 and wherein said pocket member includes a trailing edge strip member extending spanwise along said blade and positioned between said pocket inner and outer skins and cooperating therewith to define said blade trailing edge.
Claim 49
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade spar and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 50
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade spar and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 51
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade spar and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 52
Dependent Claim
56 words
A helicopter blade having a blade leading edge and a blade trailing edge and a blade chord extending therebetween and further including a blade root section and blade tip section located at opposite ends of the blade spar and including: A. a hollow structural spar of D-shaped cross section extending along the blade span and having:
Claim 53
Dependent Claim
60 words
A rotary blade hollow structural spar shaped to define the forward portion of the airfoil shape of the blade and including: A. a solid walled forward-portion extending along the blade span and defining the blade leading edge, B. a sandwich construction, walled after-portion attached to and shaped to cooperate with said forward-portion to form the blade structural spar and including:
Claim 54
Dependent Claim
60 words
A rotary blade hollow structural spar shaped to define the forward portion of the airfoil shape of the blade and including: A. a solid walled forward-portion extending along the blade span and defining the blade leading edge, B. a sandwich construction, walled after-portion attached to and shaped to cooperate with said forward-portion to form the blade structural spar and including:
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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) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |