Abstract: Structural composite airfoils include a primary structural element and a secondary structural element defining the trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. The upper skin panel extends from an upper leading edge end to an upper trailing edge end, and the lower skin panel extends from a lower leading edge end to a lower trailing edge end. The lower leading edge end of the lower skin panel is coupled to the upper leading edge end of the upper skin panel within the leading edge region of the primary structural element.

Abstract: Structural composite airfoils include a primary structural element, a secondary structural element defining the trailing edge of the structural composite airfoil, and a discrete leading edge structure defining the leading edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. The discrete leading edge structure is coupled to the upper leading edge end of the upper skin panel and to the lower leading edge end of the lower skin panel. The upper skin panel may include a first panel bend adjacent the discrete leading edge structure, and the lower skin panel may include a second panel bend adjacent the discrete leading edge structure.

Abstract: Structural composite airfoils include a front C-channel spar having an upper flange coupled to an upper skin panel, and a lower flange coupled to a lower skin panel. The lower skin panel includes a joggle adjacent a lower leading edge end, with the joggle being positioned forward of the front C-channel spar. An upper skin surface of the lower leading edge end faces an internal volume defined between the upper skin panel and the lower skin panel. A lower skin surface of the lower leading edge end faces an internal surface of the upper leading edge end of the upper skin panel, and the lower leading edge end of the lower skin panel is coupled to the upper leading edge end of the upper skin panel forward of the front C-channel spar. The leading edge has a bullnose shape defined by the upper skin panel.

Abstract: Structural composite airfoils include a primary structural element and a secondary structural element defining a trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. An upper flange of the middle C-channel spar is coupled to the upper skin panel, while a lower flange of the middle C-channel spar is coupled to the upper skin panel and the lower skin panel. An internal volume is defined by the upper skin panel and the lower skin panel aft of the middle C-channel spar, and is defined by the upper skin panel forward of the middle C-channel spar. The leading edge region of the primary structural element defines the leading edge of the structural composite airfoil.

Abstract: Structural composite airfoils include 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 spar. A first channel of the front C-channel spar faces the leading edge of the structural composite airfoil, and an upper flange of the front C-channel spar forms an acute angle with an elongated span of the front C-channel spar. The leading edge skin panel is positioned adjacent the leading edge region of the primary structural element, with a first end region of the leading edge skin panel being coupled to the upper flange of the front C-channel spar, and a second end region being coupled to the lower flange of the front C-channel spar.

Abstract: Structural composite airfoils include a primary structural element and a secondary structural element defining the trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. The upper skin panel extends from an upper leading edge end to an upper trailing edge end, and the lower skin panel extends from a lower leading edge end to a lower trailing edge end. The lower leading edge end of the lower skin panel is coupled to the upper leading edge end of the upper skin panel within the leading edge region of the primary structural element.

Abstract: Structural composite airfoils include a primary structural element and a secondary structural element defining a trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. An upper flange of the middle C-channel spar is coupled to the upper skin panel, while a lower flange of the middle C-channel spar is coupled to the upper skin panel and the lower skin panel. An internal volume is defined by the upper skin panel and the lower skin panel aft of the middle C-channel spar, and is defined by the upper skin panel forward of the middle C-channel spar. The leading edge region of the primary structural element defines the leading edge of the structural composite airfoil.

Abstract: Structural composite airfoils include a front C-channel spar having an upper flange coupled to an upper skin panel, and a lower flange coupled to a lower skin panel. The upper skin panel includes a joggle adjacent an upper leading edge end, with the joggle being positioned forward of the front C-channel spar. A lower skin surface of the upper leading edge end faces an internal volume defined between the upper skin panel and the lower skin panel. An upper skin surface of the upper leading edge end faces an internal surface of the lower leading edge end of the lower skin panel, and the upper leading edge end of the upper skin panel is coupled to the lower leading edge end of the lower skin panel forward of the front C-channel spar. The leading edge has a bullnose shape defined by the lower skin panel.

Abstract: A structural composite airfoil includes a primary structural element, and a secondary structural element defining a trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel extending from an upper leading edge end to an upper trailing edge end, a lower skin panel extending from a lower leading edge end to a lower trailing edge end, and a bracket coupled to the upper skin panel. The leading edge region of the primary structural element has a bullnose shape defined by the upper skin panel. The lower skin panel includes an integrally formed front C-channel spar having an upper flange coupled to the upper skin panel. The upper flange is adjacent the lower leading edge end, and the integrally formed front C-channel spar is coupled to the bracket, thereby coupling the upper skin panel to the integrally formed front C-channel spar.

Abstract: Structural composite airfoils include a primary structural element, and a secondary structural element defining a trailing edge of the structural composite airfoil. The primary structural element extends from a leading edge region to a trailing edge region, with the leading edge region of the primary structural element forming a leading edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a spar. The spar includes a plurality of upper flanges coupled to the upper skin panel and a plurality of lower flanges coupled to the lower skin panel. The spar extends spanwise across the structural composite airfoil. The spar also extends along a chord length of the structural composite airfoil. The spar may be a unitary, monolithic body, with an elongated span extending between each adjacent upper flange and lower flange.

Abstract: Structural composite airfoils include a front C-channel spar having an upper flange coupled to an upper skin panel, and a lower flange coupled to a lower skin panel. The lower skin panel includes a joggle adjacent a lower leading edge end, with the joggle being positioned forward of the front C-channel spar. An upper skin surface of the lower leading edge end faces an internal volume defined between the upper skin panel and the lower skin panel. A lower skin surface of the lower leading edge end faces an internal surface of the upper leading edge end of the upper skin panel, and the lower leading edge end of the lower skin panel is coupled to the upper leading edge end of the upper skin panel forward of the front C-channel spar. The leading edge has a bullnose shape defined by the upper skin panel.

Abstract: Structural composite airfoils include a primary structural element, a secondary structural element defining the trailing edge of the structural composite airfoil, and a discrete leading edge structure defining the leading edge of the structural composite airfoil. The primary structural element includes an upper skin panel, a lower skin panel, and a middle C-channel spar that is coupled to the upper skin panel and the lower skin panel. The discrete leading edge structure is coupled to the upper leading edge end of the upper skin panel and to the lower leading edge end of the lower skin panel. The upper skin panel may include a first panel bend adjacent the discrete leading edge structure, and the lower skin panel may include a second panel bend adjacent the discrete leading edge structure.

Abstract: A structural composite airfoil includes a primary structural element, and a secondary structural element defining a trailing edge of the structural composite airfoil. The primary structural element includes an upper skin panel extending from an upper leading edge end to an upper trailing edge end, a lower skin panel extending from a lower leading edge end to a lower trailing edge end, and a bracket coupled to the lower skin panel. The leading edge region of the primary structural element has a bullnose shape defined by the lower skin panel. The upper skin panel includes an integrally formed front C-channel spar having a lower flange coupled to the lower skin panel. The lower flange is adjacent the upper leading edge end, and the integrally formed front C-channel spar is coupled to the bracket, thereby further coupling the lower skin panel to the integrally formed front C-channel spar.