Abstract: An adjustable cable attachment system for a VTOL aircraft includes a VTOL airframe. A winch is operatively connected to an underside of the airframe with the aircraft in a horizontal flight mode. An adjustable cable is operatively connected to the winch to adjustably relocate a slung load with respect to the center of gravity of the aircraft to balance the aircraft. A fixed cable is operatively connected to the underside of the airframe with the aircraft in the horizontal flight mode.

Abstract: An aircraft is provided and includes a fuselage from which a tilt-wing respectively extends, first prop-rotors, which are formed to define first rotor disks and which are respectively disposed on first portions of each side of the tilt-wing, second prop-rotors, which are formed to define second rotor disks and which are respectively disposed on second portions of each side of the tilt-wing such that the corresponding pairs of first and second rotor disks overlap, and a drive shaft system. The drive shaft system is configured to synchronize respective operations of the first and second prop-rotors.

Abstract: An aircraft includes a fuselage defining an aircraft attitude axis. The fuselage houses an engine fixed relative to the aircraft attitude axis. A rotor assembly is operatively connected to rotate back and forth relative to the aircraft attitude axis from a first position predominately for lift to a second position predominately for thrust. The rotor assembly includes a rotor that is operatively connected to be driven by the engine.

Abstract: A method for determining a center-of-gravity of an aircraft in three dimensions includes determining a first center-of-gravity location for an aircraft in a first plane defined by a first axis and a second axis. The method includes positioning the aircraft in a tilted position by rotating the aircraft and determining a second center-of-gravity location for the aircraft in the first plane in the tilted position. The method includes comparing the first center-of-gravity location to the second center-of-gravity location to determine a component of the first center-of-gravity location along a third axis defined out-of-plane from the first plane to determine a three-dimensional center-of-gravity of the aircraft.

Abstract: An aircraft is provided and includes a fuselage, first and second wings extending outwardly from opposite sides of the fuselage, proprotors operably disposed on each of the first and second wings to drive vertical take-off and landing aircraft operations and horizontal flight aircraft operations and a refueling system including at least one fuel tank disposed in at least one or more of the fuselage, the first wing or the second wing and a refueling apparatus. The refueling apparatus is coupled to the at least one fuel tank such that fuel is movable with respect to the at least one fuel tank during aircraft ground and aerial operations.

Abstract: A tail-sitter aircraft is provided and includes a fuselage having first and second axisymmetric sides, first collectively controllable prop-rotors, which are formed to define a first pair of rotor disks and which are respectively supported at the first axisymmetric side of the fuselage, and second collectively controllable prop-rotors, which are formed to define a second pair of rotor disks and which are respectively supported at the second axisymmetric side of the fuselage.

Abstract: An aircraft is provided and includes a fuselage, first and second wings extending outwardly from opposite sides of the fuselage, proprotors operably disposed on each of the first and second wings to drive vertical take-off and landing aircraft operations and horizontal flight aircraft operations and a refueling system including at least one fuel tank disposed in at least one or more of the fuselage, the first wing or the second wing and a refueling apparatus. The refueling apparatus is coupled to the at least one fuel tank such that fuel is movable with respect to the at least one fuel tank during aircraft ground and aerial operations.

Abstract: An aircraft is provided and includes a propeller to generate aircraft thrust, a prop-nacelle housing and supporting the propeller, a wing supporting the prop nacelle and including first coupling elements. The first coupling elements are each configured to selectively couple with a second set of coupling elements associated with a group of interchangeable fuselages.