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BR-102021003353-B1 - Structural Composite Airfoil, Aircraft and Assembly Method of a Structural Composite Airfoil

BR102021003353B1BR 102021003353 B1BR102021003353 B1BR 102021003353B1BR-102021003353-B1

Abstract

STRUCTURAL COMPOSITE AIRFOILS WITH DIRECTLY COUPLED FRONT STRINGERS AND RELATED METHODS. The present invention relates to structural composite airfoils comprising a primary structural element, a secondary structural element defining the trailing edge of the structural composite airfoil, and a leading edge skin panel defining the leading edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a front C-channel stringer. A first channel of the front C-channel stringer faces the leading edge of the structural composite airfoil, and an upper flange of the front C-channel stringer forms an acute angle with an elongated extension of the front C-channel stringer. The leading edge cladding panel is positioned adjacent to the leading edge region of the primary structural element, with a first end region of the leading edge cladding panel being coupled to the upper flange of the front C-channel stringer and a second end region being coupled to the lower flange of the front C-channel stringer.

Inventors

  • Bryan Gruner
  • Peter Schupp

Assignees

  • THE BOEING COMPANY

Dates

Publication Date
20260317
Application Date
20210223
Priority Date
20200521

Claims (15)

  1. 1. Structural composite airfoil (10) having a leading edge (22) and a trailing edge (24), characterized in that it comprises: a primary structural element (26) extending from a leading edge region (30) to a trailing edge region (32), wherein the leading edge region (30) is adjacent to the leading edge (22) of the structural composite airfoil (10), wherein the primary structural element (26) comprises: an upper skin panel (34); a lower skin panel (36); an internal volume (40) defined between the upper skin panel (34) and the lower skin panel (36); and a front C-channel spar (38) comprising an upper flange (42) coupled to the upper skin panel (34), wherein the front C-channel spar (38) also comprises a lower flange (44) coupled to the lower skin panel (36), wherein a first channel (46) of the front C-channel spar (38) is facing the leading edge (22) of the structural composite airfoil (10), wherein the upper flange (42) forms a first angle (48) with an elongated extension (50) of the front C-channel spar (38), wherein the lower flange (44) forms a second angle (52) with the elongated extension (50), and wherein the first angle (48) is acute; a secondary structural element (28) defining the trailing edge (24) of the structural composite airfoil (10); a leading edge cladding panel (54) defining the leading edge (22) of the structural composite airfoil (10) and positioned adjacent to the leading edge region (30) of the primary structural element (26), wherein a first end region (56) of the leading edge cladding panel (54) is coupled to the upper flange (42) of the front C-channel spar (38), wherein a second end region (58) of the leading edge cladding panel (54) is coupled to the lower flange (44) of the front C-channel spar (38), and wherein the leading edge cladding panel (54) has a rounded shape; and a trailing edge closing cap (104), wherein: a first end cap region (118) of the trailing edge closing cap (104) is bonded to the lower cladding panel (36), and the first end cap region (118) of the trailing edge closing cap (104) is recessed into the lower cladding panel (36); and a second end cap region (120) of the trailing edge closing cap (104) comprises an integral wedge (122) coupled to the upper cladding panel (34).
  2. 2. Structural composite airfoil (10) according to claim 1, characterized in that the leading edge skin panel (54) does not overlap the upper skin panel (34) on the upper flange (42) of the front C-channel spar (38), and in that the leading edge skin panel (54) does not overlap the lower skin panel (36) on the lower flange (44) of the front C-channel spar (38).
  3. 3. Structural composite airfoil (10) according to claim 1 or 2, characterized in that it further comprises: a first fastener (80) that couples the leading edge skin panel (54) to the upper flange (42) of the front C-channel spar (38); a second fastener (82) that couples the leading edge skin panel (54) to the lower flange (44) of the front C-channel spar (38); a third fastener (84) that couples the upper skin panel (34) to the upper flange (42) of the front C-channel spar (38), wherein the third fastener is not concealed so that it is accessible when the primary structural element (26) is mounted; a fourth fastener (86) that couples the lower cladding panel (36) to the lower flange (44) of the front C-channel stringer (38), wherein the fourth fastener (86) is not concealed, so that it is accessible when the primary structural element (26) is mounted.
  4. 4. Structural composite airfoil (10) according to any one of claims 1 to 3, characterized in that the leading edge skin panel (54) interlocks with the upper skin panel (34) without any deviation, and in that the leading edge skin panel (54) interlocks with the lower skin panel (36) without any deviation.
  5. 5. Structural composite airfoil (10) according to any one of claims 1 to 4, characterized in that the structural composite airfoil (10) is a trailing edge flap, an aileron, a flaperon, a pneumatic brake, an elevator, an auxiliary airfoil, a spoiler, a canard, a rudder and/or a winglet.
  6. 6. Structural composite airfoil (10) according to any one of claims 1 to 5, characterized in that the secondary structural element (28) comprises a wedge-shaped closure.
  7. 7. Structural composite airfoil (10) according to any one of claims 1 to 6, characterized in that: the lower skin panel (36) comprises a lower leading edge end (78) and a lower trailing edge end (94), wherein the lower trailing edge end is opposite the lower leading edge end (22); the lower leading edge end (22) is coupled to the forward C-channel spar (38); and optionally, the lower trailing edge end is coupled to an upper trailing edge end (92) of the upper skin panel (34).
  8. 8. Structural composite airfoil (10) according to claim 7, characterized in that: an integral Z spar (100) is formed at the lower end of the trailing edge (94), the integral Z spar (100) including a Z spar offset (102); and the first end region of the leading edge closing cap (118) is recessed into the lower skin panel (36) by means of the Z spar offset (102).
  9. 9. Structural composite airfoil (10) according to claim 8, characterized in that the integral wedge is at least one of which is joined and coupled to the upper skin panel (34) by means of one or more fasteners.
  10. 10. Structural composite airfoil (10) according to any one of claims 1 to 6, characterized in that: the upper skin panel (34) comprises an upper end of the leading edge (76) and an upper end of the trailing edge (92), the upper end of the trailing edge (92) is opposite the upper end of the leading edge (76); the upper end of the leading edge (76) is coupled to the forward C-channel spar (38); and, optionally, the end of the upper end of the trailing edge (92) is coupled to an integral wedge (122) of a trailing edge closing cap (104).
  11. 11. Structural composite airfoil (10) according to any one of claims 1 to 10, characterized in that the second angle is acute.
  12. 12. Structural composite airfoil (10) according to any one of claims 1 to 11, characterized in that the front C-channel spar (38) is directly coupled to the upper skin panel (34) and the lower skin panel (36) without splicing strips or nut plates.
  13. 13. Structural composite airfoil (10) according to any one of claims 1 to 12, characterized in that the primary structural element (26) also comprises: an intermediate C-channel spar (60) coupled to the upper skin panel (34) and to the lower skin panel (36), wherein a second channel (64) of the intermediate C-channel spar (60) faces the leading edge of the structural composite airfoil (10), and wherein the intermediate C-channel spar (60) is positioned behind the front C-channel spar; and a rear C-channel spar (62) coupled to the upper skin panel (34) and to the lower skin panel (36), wherein a third channel (70) of the rear C-channel spar faces the leading edge of the structural composite airfoil (10) and wherein the rear C-channel spar is positioned behind the intermediate C-channel spar (60).
  14. 14. Aircraft, characterized in that it comprises the structural composite airfoil (10) as defined in any one of claims 1 to 13.
  15. 15. Assembling a structural composite airfoil (10), characterized in that it comprises: coupling an upper skin panel (34) to a front C-channel spar (38), wherein the structural composite airfoil (10) extends from a leading edge (22) to a trailing edge (24), wherein a first channel (46) of the front C-channel spar (38) faces the leading edge of the structural composite airfoil (10), wherein the front C-channel spar (38) comprises an upper flange (42), a lower flange (44) and an elongated extension (50) extending between the upper flange (42) and the lower flange (44), wherein the coupling of the upper skin panel (34) to the front C-channel spar (38) includes the coupling of the upper skin panel (34) to the upper flange (42) of the front C-channel spar (38), and wherein the upper flange (42) forms an acute angle with the elongated extension (50); couple a lower skin panel (36) to the front C-channel spar (38) so as to define an internal volume (40) between the upper skin panel (34) and the lower skin panel (36), in which the upper skin panel (34), the lower skin panel (36) and the front C-channel spar (38) form at least a portion of a primary structural element (26) of the structural composite airfoil (10); coupling a leading edge cladding panel (54) to the front C-channel spar, wherein the leading edge cladding panel (54) defines the leading edge of the structural composite airfoil (10), wherein the coupling of the leading edge cladding panel (54) comprises the coupling of a first end region (56) of the leading edge cladding panel (54) to the upper flange (42) of the front C-channel spar (38), wherein the coupling of the leading edge panel further comprises the coupling of a second end region (58) of the leading edge panel to the lower flange (44) of the front C-channel spar (38), wherein the leading edge panel has a rounded shape; ecoupling a trailing edge closure cap (104) to the lower cladding panel (36), wherein a first cap end region (118) of the trailing edge closure cap (104) is bonded to the lower cladding panel (36), the first cap end region (118) of the trailing edge closure cap (104) is recessed within the lower cladding panel (36), and a second cap end region (120) of the trailing edge closure cap (104) comprises an integral wedge (122) coupled to the upper cladding panel (34).

Description

TECHNICAL FIELD [001] The present invention relates generally to structural composite airfoils and related methods. BACKGROUND OF THE INVENTION [002] Aircraft, including fixed-wing and rotary-wing aircraft, utilize a variety of aerodynamic control surfaces, such as ailerons, air brakes, elevators, flaps, rudders, auxiliary airfoils, spoilers, and the like. By manipulating one or more aerodynamic control surfaces, a pilot can control the lift generated by the aircraft, such as during takeoff, climb, descent, and landing, as well as the aircraft's orientation about its pitch, roll, and yaw axes. For example, the trailing edge of a fixed-wing aircraft wing typically includes one or more flaps, with the flaps being movable between retracted and extended positions. In cruise, the flaps are typically held in a retracted position. When extended, the flaps increase the wing's camber. Therefore, during takeoff, climb, descent, or landing, the flaps can be extended, partially or fully, to increase the maximum lift coefficient and effectively reduce the aircraft's stall speed. These aerodynamic control surfaces are typically airfoils formed from composite materials and are therefore referred to here as structural composite airfoils. [003] Structural composite airfoils, such as flaps, have an aerodynamic cross-section that is typically formed by joining an upper skin to a lower skin near both the leading edge and the trailing edge of the structural composite airfoil. In conventional construction of inner and outer flaps, for example, a primary structural element of the flap is defined by joining the upper and lower skins to three spars that increase the width of the flap. The leading edge of the structural composite airfoil (which typically includes a rounded shape), and the trailing edge (which is tapered in a thin cross-section) are typically outside the primary structural element, forming the respective secondary structural elements of the flap. Various fasteners and components (e.g., splicing strips and/or nut plates) are used to attach the upper and lower skins to the spars and other structures that form the flap. Many fasteners can increase the costs, manufacturing cycle time, and weight of the resulting assemblies. Therefore, experts in the field continue research and development efforts aimed at improving structural composite airfoils and their manufacture. SUMMARY [004] Structural composite airfoils and related methods for forming said structural composite airfoils, as described herein, can reduce the number of fasteners, improve the aerodynamic surfaces of the airfoil and/or simplify the manufacturing processes of structural composite airfoils. [005] An example of a structural composite airfoil according to the present invention includes a primary structural element, a secondary structural element that defines a trailing edge of the structural composite airfoil, and a leading edge skin panel that defines a leading edge of the structural composite airfoil. The structural composite airfoil has a leading edge and a trailing edge, and the primary structural element extends from a leading edge region to a trailing edge region. The leading edge region of the primary structural element is adjacent to the leading edge of the structural composite airfoil. [006] The primary structural element includes an upper skin panel, a lower skin panel, and a front C-channel spar. An internal volume is defined between the upper skin panel and the lower skin panel. The front C-channel spar includes an upper flange coupled to the upper skin panel and a lower flange coupled to the lower skin panel. A first channel of the front C-channel spar faces the leading edge of the structural composite airfoil, and the upper flange forms an acute angle with an elongated extension of the front C-channel spar. [007] The leading edge cladding panel is positioned adjacent to the leading edge region of the primary structural element, wherein a first end region of the leading edge cladding panel is coupled to the upper flange of the front C-channel stringer, wherein a second end region of the leading edge cladding panel is coupled to the lower flange of the front C-channel stringer, and wherein the leading edge cladding panel has a rounded shape. [008] Methods for mounting such structural composite airfoils are also described. In these methods, the upper skin panel is coupled to the upper flange of the front C-channel spar, the lower skin panel is coupled to the lower flange of the front C-channel spar so that the internal volume is defined between the upper skin panel and the lower skin panel, and the leading edge skin panel is coupled to the front C-channel spar. For example, the first end region of the leading edge skin panel is coupled to the upper flange of the front C-channel spar, and the second end region of the leading edge skin panel is coupled to the lower flange of the front C-channel spar. BRIEF DESCRIPTION OF THE DRAWINGS [009] Figure 1