Shifting a center of gravity of an aircraft

#The present disclosure relates generally to the field of aircraft, and more specifically to shifting a center of gravity of an aircraft based on a change in mobility phase of the aircraft.

#In different types of aircraft, the desired location of the aircraft's center of gravity —i.e., a balance location of the aircraft's mass, may depend on a variety of factors including a mobility phase in which the aircraft is operating. As one example, for an aircraft designed to operate in a hover mobility phase (e.g., a helicopter), a center of gravity of the aircraft is preferably collocated with a center of lift of the aircraft—i.e., a balance location of the aircraft's vertical thrust that enables hovering. By collocating the center of gravity with the center of lift, a load of the aircraft is equally balanced between all propulsors (e.g., rotors) of the aircraft, and the aircraft is able to provide power-efficient hovering without any one propulsor being loaded more than any other propulsor.

#As another example, for an aircraft designed to operate primarily in a cruising mobility phase (e.g., a passenger jet), a center of gravity of the aircraft is preferably positioned forward in a longitudinal direction from a center of pressure of the aircraft—i.e., a balance location of upward aerodynamic loads on the aircraft in forward cruise flight. By positioning the center of gravity ahead of the center of pressure, positive static stability (i.e., static margin) is achieved while in the cruising mobility phase. Accordingly, the balance of aircraft mass and aerodynamic forces in a statically stable aircraft operates to passively reject small disturbances to pitch, thereby increasing stability and efficiency per flight phase.

#FIGS. 1A, 1B, 2A, and 2B are diagrammatic representations of an exemplary embodiment of an aircraft configured to shift a center of gravity of the aircraft based on transitioning between different phases of mobility.

#FIGS. 3A and 3B are diagrammatic representations of an exemplary embodiment of an aircraft comprising a moveable ballast component positioned in a fuselage of the aircraft.

#FIGS. 4A-4D are diagrammatic representations of an exemplary embodiment of an apparatus for shifting a center of gravity of an aircraft comprising a four-bar linkage.

#Different aircraft may have differently positioned and fixed centers of gravity depending on the mobility phase in which the aircraft is designed to operate. Some aircraft are designed to transition between operation in different mobility phases, which can present issues when the center of gravity is misaligned for a particular mobility phase. For example, a vertical-take-off-and-landing (VTOL) aircraft may transition through a sequence of different mobility phases beginning with vertical takeoff, hover climb, hover, outbound transition, climb, cruise and maneuver, descent, inbound transition, hover and reserve, and vertical landing. In such a VTOL aircraft, if the center of gravity is fixed, then the aircraft is optimized for only some of the mobility phases and not the other mobility phases.

#Thus, examples are disclosed that relate to shifting a center of gravity of an aircraft based on the aircraft transitioning from one mobility phase to another mobility phase. Such mobility phase-based shifting of the center of gravity allows for the center of gravity to be optimally positioned in the aircraft according to the particular mobility phase in which the aircraft is operating. As described in more detail below, the center of gravity of an aircraft can be shifted in different ways using a variety of different assemblies.

#FIGS. 1A, 1B, 2A, and 2B are diagrammatic representations of an exemplary embodiment of an aircraft 100 according to examples of the present disclosure. The aircraft 100 is an exemplary embodiment of a VTOL aircraft. The aircraft 100 is configured to operate in a hover mobility phase as shown in FIGS. 1A and 2A. For example, the aircraft 100 may operate in the hover mobility phase that includes vertical take-off, hover climb, hover, hover and reserve and vertical landing. Further, the aircraft 100 is configured to transition between operating in the hover mobility phase and operating in a cruising mobility phase as shown in FIGS. 1B and 2B. Note that aircraft 100 may operate in other intermediate mobility phases when transitioning between the hover phase and the cruising phase (e.g., outbound transition, inbound transition).