Technologies are described herein for a drag recovery scheme using a boundary layer bypass duct system. In some examples, boundary layer air is routed around the intake of one or more of the engines and reintroduced aft of the engine fan in the nozzle duct in a mixer-ejector scheme. Mixer-ejectors mix the boundary layer flow to increase mass flow.

Technologies are described herein for a drag recovery scheme using a boundary layer bypass duct system. In some examples, boundary layer air is routed around the intake of one or more of the engines and reintroduced aft of the engine fan in the nozzle duct in a mixer-ejector scheme. Mixer-ejectors mix the boundary layer flow to increase mass flow.

An aircraft (2) comprises at least first and second gas turbine engines (10a, 10b) arranged in a line extending generally normally to an aircraft longitudinal axis (A), each engine (10a, 10b) comprising at least one compressor or turbine rotor disc (32-42) defining a respective rotational plane (D.sub.32-D.sub.42). The rotational plane (D.sub.32-D.sub.42) of at least one of the rotors (32-42) of at least one of the engines (10a, 10b) is angled relative to the aircraft longitudinal line (A) such that a burst disc plane of the respective engine (10a, 10b) is nonintersecting with another engine (10a, 10b).

An aircraft (2) comprises at least first and second gas turbine engines (10a, 10b) arranged in a line extending generally normally to an aircraft longitudinal axis (A), each engine (10a, 10b) comprising at least one compressor or turbine rotor disc (32-42) defining a respective rotational plane (D.sub.32-D.sub.42). The rotational plane (D.sub.32-D.sub.42) of at least one of the rotors (32-42) of at least one of the engines (10a, 10b) is angled relative to the aircraft longitudinal line (A) such that a burst disc plane of the respective engine (10a, 10b) is nonintersecting with another engine (10a, 10b).

A span-loaded, highly flexible flying wing, having horizontal control surfaces mounted aft of the wing on extended beams to form local pitch-control devices. Each of five spanwise wing segments of the wing has one or more motors and photovoltaic arrays, and produces its own lift independent of the other wing segments, to minimize inter-segment loads. Wing dihedral is controlled by separately controlling the local pitch-control devices consisting of a control surface on a boom, such that inboard and outboard wing segment pitch changes relative to each other, and thus relative inboard and outboard lift is varied.

A span-loaded, highly flexible flying wing, having horizontal control surfaces mounted aft of the wing on extended beams to form local pitch-control devices. Each of five spanwise wing segments of the wing has one or more motors and photovoltaic arrays, and produces its own lift independent of the other wing segments, to minimize inter-segment loads. Wing dihedral is controlled by separately controlling the local pitch-control devices consisting of a control surface on a boom, such that inboard and outboard wing segment pitch changes relative to each other, and thus relative inboard and outboard lift is varied.

An aircraft having a blended-wing-body configuration includes a centerbody, a pair of wings, at least one pair of engines, a pair of air inlets, and a pair of exhaust outlets. The centerbody has an airfoil-shaped cross section, an aircraft centerline, an aft portion, an upper mold line, a lower mold line, and a pair of centerbody leading edge portions respectively on opposite sides of the aircraft centerline. The wings are integral with the centerbody. The pair of engines are located on opposite sides of the aircraft centerline and are mounted within the centerbody between the upper mold line and the lower mold line. The pair of air inlets are located respectively along the centerbody leading edge portions and are respectively fluidly coupled to the pair of engines. The pair of exhaust outlets our located in the aft portion of the centerbody and our respectively fluidly coupled to the pair of engines.

An aircraft having a blended-wing-body configuration includes a centerbody, a pair of wings, at least one pair of engines, a pair of air inlets, and a pair of exhaust outlets. The centerbody has an airfoil-shaped cross section, an aircraft centerline, an aft portion, an upper mold line, a lower mold line, and a pair of centerbody leading edge portions respectively on opposite sides of the aircraft centerline. The wings are integral with the centerbody. The pair of engines are located on opposite sides of the aircraft centerline and are mounted within the centerbody between the upper mold line and the lower mold line. The pair of air inlets are located respectively along the centerbody leading edge portions and are respectively fluidly coupled to the pair of engines. The pair of exhaust outlets our located in the aft portion of the centerbody and our respectively fluidly coupled to the pair of engines.

Systems and methods for mechanically rotating an aircraft about its center-of-gravity (C.sub.G) are disclosed. The system can enable the rear, or main, landing gear to squat, while the nose landing gear raises to generate a positive angle of attack for the aircraft for takeoff or landing. The system can also enable the nose gear and main gear to return to a relatively level fuselage attitude for ground operations. The system can include one or more hydraulically linked hydraulic cylinders to control the overall height of the nose gear and the main gear. Because the hydraulic cylinders are linked, a change on the length of the nose cylinder generates a proportional, and opposite, change in the length of the main cylinder, and vice-versa. A method and control system for monitoring and controlling the relative positions of the nose gear and main gear is also disclosed.

Systems and methods for mechanically rotating an aircraft about its center-of-gravity (C.sub.G) are disclosed. The system can enable the rear, or main, landing gear to squat, while the nose landing gear raises to generate a positive angle of attack for the aircraft for takeoff or landing. The system can also enable the nose gear and main gear to return to a relatively level fuselage attitude for ground operations. The system can include one or more hydraulically linked hydraulic cylinders to control the overall height of the nose gear and the main gear. Because the hydraulic cylinders are linked, a change on the length of the nose cylinder generates a proportional, and opposite, change in the length of the main cylinder, and vice-versa. A method and control system for monitoring and controlling the relative positions of the nose gear and main gear is also disclosed.