Abstract: Subsonic turbofan engines with variable outer guide vanes (OGVs) and associated methods. A subsonic turbofan engine includes an engine core configured to generate a torque, a fan configured to accelerate an air flow, an engine nacelle, and a plurality of OGVs positioned downstream of the fan. Each OGV is configured to transition among a plurality of OGV configurations defined between and including a nominal configuration and a reduced-drag configuration. The subsonic turbofan engine is configured to operate only at subsonic speeds. In examples, methods of operating a subsonic turbofan engine include transitioning each of a plurality of OGVs from a nominal configuration to a reduced-drag configuration. Transitioning each OGV from the nominal configuration to the reduced-drag configuration is performed while the subsonic engine operates at subsonic speeds.

Abstract: Subsonic turbofan engines with variable outer guide vanes (OGVs) and associated methods. A subsonic turbofan engine includes an engine core configured to generate a torque, a fan configured to accelerate an air flow, an engine nacelle, and a plurality of OGVs positioned downstream of the fan. Each OGV is configured to transition among a plurality of OGV configurations defined between and including a nominal configuration and a reduced-drag configuration. The subsonic turbofan engine is configured to operate only at subsonic speeds. In examples, methods of operating a subsonic turbofan engine include transitioning each of a plurality of OGVs from a nominal configuration to a reduced-drag configuration. Transitioning each OGV from the nominal configuration to the reduced-drag configuration is performed while the subsonic engine operates at subsonic speeds.

Abstract: An ultrashort nacelle configuration employs a fan cowl having an exit plane and a serrated trailing edge. A variable pitch fan is housed within the fan cowl. The variable pitch fan has a reverse thrust position inducing a reverse flow through the exit plane and into the fan cowl. The serrated trailing edge forms a plurality of vortex generators configured to induce vortices in the reverse flow.

Abstract: An ultrashort nacelle configuration employs a fan cowl having an exit plane and a serrated trailing edge. A variable pitch fan is housed within the fan cowl. The variable pitch fan has a reverse thrust position inducing a reverse flow through the exit plane and into the fan cowl. The serrated trailing edge forms a plurality of vortex generators configured to induce vortices in the reverse flow.

Abstract: A blended wing body cargo aircraft is disclosed. A body section defines a cargo volume, where an outer surface of the body section is shaped to provide an aerodynamic lifting surface. A cargo door and ramp structure is located in an aft end of the body section and is shaped to conform to an outer shape of the aerodynamic lifting surface when in a closed position. A control surface has a slightly cambered downward shape, and is positioned substantially near an aft end of the cargo door and ramp structure.

Abstract: A required payload volume of a Blended Wing Body air vehicle is determined and analyzed for a list of corner points that is passed to a Loft Module as keep-out points to be enclosed by a body portion established using a faceted minimum volume. Trapezoidal wing shape and size are determined, a leading edge of the body portion and trapezoidal wing leading edge are trimmed and a trailing edge of the body portion and trapezoidal wing trailing edge are blended. A leading edge elevation is established and with leading edge radius as an input smoothly encloses the payload volume in a first set of defined aerodynamic sections. A second set of aerodynamic sections and transition sections between the body portion and the trapezoidal wing are defined. The blended wing body is then lofted based on the defined sections.

Abstract: A blended wing body cargo aircraft is disclosed. A body section defines a cargo volume, where an outer surface of the body section is shaped to provide an aerodynamic lifting surface. A cargo door and ramp structure is located in an aft end of the body section and is shaped to conform to an outer shape of the aerodynamic lifting surface when in a closed position. A control surface has a slightly cambered downward shape, and is positioned substantially near an aft end of the cargo door and ramp structure.

Abstract: Lofting of a Blended Wing Body air vehicle is accomplished by first determining the required payload volume of the air vehicle. The payload volume is then analyzed to determine a list of corner points of the payload volume. The list of points is passed to a Loft Module as keep-out points and a body portion of the blended wing body is established using a faceted minimum volume which encloses all of the provided keep-out points. A trapezoidal wing shape and size is then determined to accommodate aerodynamic performance requirements. A leading edge of the body portion and trapezoidal wing leading edge are trimmed and a trailing edge of the body portion and trapezoidal wing trailing edge are blended. A leading edge elevation is established and with leading edge radius as an input all other point coordinates and all tangents and remaining curvatures to smoothly enclose the payload volume in a first set of aerodynamic sections are defined.