Abstract: An aircraft having omnidirectional ground maneuver capabilities. The aircraft includes an airframe and a plurality of propulsion assemblies attached to the airframe. Each of the propulsion assemblies includes a nacelle having a mast axis, a rotor assembly having a tilting degree of freedom relative to the mast axis and a tail assembly rotatable about the mast axis. The tail assembly includes at least one wheel having a rotational axis. A flight control system is operable to independently control each of the propulsion assemblies including tilting each rotor assembly and rotating each tail assembly. For each propulsion assembly, the rotor assembly and the tail assembly have complementary configurations in which a thrust vector generated by the rotor assembly has a horizontal component that is generally perpendicular to the rotational axis of the wheel, thereby enabling omnidirectional ground maneuvers.

Abstract: A proprotor assembly for a tiltrotor aircraft having a forward flight mode. The proprotor assembly includes a spinner subjected to freestream airflow during forward flight. The spinner is elongated to form a tapered leading portion and a substantially cylindrical aft portion. The spinner forms a plurality of rotor blade cutouts exposing an inner chamber. The proprotor assembly includes a plurality of proprotor blade assemblies protruding radially from the spinner through the rotor blade cutouts. The rotor blade cutouts are formed at the substantially cylindrical aft portion of the spinner to reduce the freestream airflow into the inner chamber via the rotor blade cutouts during forward flight, thereby reducing drag experienced by the tiltrotor aircraft.

Abstract: In one aspect, a spinner fairing includes a base configured to be fixed relative to a hub system; a movable spinner assembly movable relative to the base; the movable spinner assembly comprising a first movable member and a second movable member. Each first and second movable member being selectively configurable between a closed position and a contracted position, in which the movable spinner assembly has a decreased shape and/or volume. In another embodiment, a spinner fairing can include at least one static member and a moveable member. In still another embodiment, a rotor head fairing assembly includes an upper housing and a lower housing coupled to a hub system; the upper housing including an upper movable member; the lower housing comprising a lower movable member. In yet another embodiment, a rotor head fairing includes at least one moveable upper housing and lower housing.

Abstract: One example of an actuation system includes a pneumatic muscle connected to a component to be actuated. The system also includes an actuation member connected in series to the pneumatic muscle and valve connected to the pneumatic muscle to control a pressure in the pneumatic muscle. The system also includes a positioning mechanism connected to the component to control a movement of the component and a controller connected to the pneumatic muscle, the valve, and the positioning mechanism, the controller to control actuation of the component by controlling the pressure in the pneumatic muscle.

Abstract: A system includes a first mast torque transfer system, a second mast torque transfer system coupled to the first mast torque transfer system, and a torque limiting system. The torque limiting system includes a first sensor configured to determine a torque of the first mast torque transfer system, a second sensor configured to determine a torque of the second mast torque transfer system, and a processor configured to determine a differential torque between the torque of the first mast torque transfer system and the torque of the second mast torque transfer system and configured to control at least one of a torque input and a torque output to at least one of the first and second mast torque transfer systems as a function of the determined differential torque.

Abstract: A method of manufacturing a composite core can include: wrapping a mandrel in a mandrel wrapping process by securing a mandrel with a winding jig; orienting the composite material at a wrap angle to the mandrel; and depositing the composite material around a circumference of the mandrel. The method can further include assembling the wrapped mandrels in a tool and applying a pressure to the composite material during a curing cycle.

Abstract: An adapter is disclosed for use with an aircraft including wingtip stations defining mounting surfaces. The adapter is configured and dimensioned for connection to the wingtip stations on either wing of the aircraft to facilitate the connection of a weapons rack to the aircraft. The adapter includes a backing plate, and a body connected to the backing plate that is configured and dimensioned to support the weapons rack. The backing plate is configured and dimensioned in correspondence with the mounting surfaces defined by the wingtip stations. The body includes a base extending outwardly from the backing plate along a first axis, and a support member extending outwardly from the base along a second axis. In one particular embodiment of the adapter, the first and second axes define an angle of 45° therebetween.

Abstract: A mounting assembly for mounting a portion of an engine exhaust duct in an opening of an airframe panel aircraft, including a peripheral flange disposed on the portion of the exhaust duct, and at least one mounting member having an outer peripheral flange portion for connection to the airframe panel and having an inner peripheral flange portion with at least one compliant isolator member to receive the peripheral flange of the exhaust duct in a manner that suspends the exhaust duct in the opening away from the airframe panel and accommodates thermal expansion and contraction of the exhaust duct relative to the airframe panel. Embodiments include a method of mounting an engine exhaust duct in an opening of an outer airframe panel of an aircraft.

Abstract: An aircraft rotor assembly has a yoke with at least two arms extending therefrom. The yoke is attached to a mast through a constant-velocity joint, thereby permitting axial tilt of the yoke relative to the mast. Each arm of the yoke includes an axisymmetric elastomeric bearing with a spherical central member and two opposite partially-spherical members attached to the central member. Each axisymmetric bearing cooperates with a cup and a bracket. Each cup is attached to one of the yoke arms and each bracket is attached to a blade cuff.

Abstract: An aircraft has an ethanol fuel storage, an ethanol-fueled fuel cell selectively connected to the ethanol fuel storage, and a power management unit configured to receive electrical power from the ethanol-fueled fuel cell.

Abstract: An aircraft has a fuel cell, a battery configured to be charged by the fuel cell, a supercapacitor configured to be charged by the fuel cell, and a power management unit configured to receive electrical power from the fuel cell, the battery, and the supercapacitor.

Abstract: An inflight connection system for aircraft having at least one wing with a wingtip includes, for each aircraft, a primary connector selectively extendable from the wingtip, an alignment connector selectively extendable from the wingtip and a male and female connector assembly disposed proximate the wingtip. The primary connectors extend a greater distance from the wingtips than the alignment connectors such that the primary connectors form a first connection between the aircraft when the aircraft are flying in a connection pattern. Thereafter, retraction of the primary connectors reduces wingtip separation of the aircraft such that the alignment connectors form a second connection between the aircraft establishing coarse alignment therebetween. Thereafter, retraction of the primary and alignment connectors further reduces wingtip separation of the aircraft such that the male and female connector assemblies form a third connection between the aircraft establishing fine alignment therebetween.

Abstract: A rotor system includes a hub assembly, a first, second, and third rotor blade rotatably attached to the hub assembly, a first, second, and third damper pivotally attached to the hub assembly and pivotally attached to the first, second, and third rotor blade, respectively, and a control system operably associated with the first, second, and third damper. A method to control vibratory forces exerted on the hub assembly via the first and second rotor blade includes separately controlling a dynamic spring rate of each of the first and second dampers with the control system.

Abstract: A fuel system for an aircraft includes a fuel cell having a plurality of sides including a first side and at least one deformable clip having a secured end and a free end. The secured end is coupled to the first side of the fuel cell and the free end overlapping the airframe of the aircraft such that the first side of the fuel cell is positioned adjacent to the airframe. The at least one deformable clip is deformable to allow the fuel cell to move independently of the airframe in response to an impact of the aircraft, thereby protecting the fuel cell from damage resulting from the impact.

Abstract: A split winglet has a leading airfoil (LA) comprising a LA leading edge, a LA trailing edge, a LA upper surface, and a LA lower surface. The split winglet also has a trailing airfoil (TA) comprising a TA leading edge, a TA trailing edge, a TA upper surface, and a TA lower surface. The split winglet further has a base connected to each of the LA and the TA, the base being configured for connection to a tip of a main airfoil.

Abstract: A rotor blade system includes a rotor blade having an outboard section and an inboard section, a hinge joint rigidly attached to the outboard section, and an adhedral tip engaged with the hinge joint. A method includes pivotally attaching an adhedral tip to the rotor blade and pivoting the adhedral tip during flight to change the flight performance characteristics of the blade during flight.

Abstract: In some embodiments, an aircraft includes a fuselage having a forward portion and an aft portion. First and second ducted fans are supported by the forward portion of the fuselage. The first and second ducted fans are tiltable relative to the fuselage between a generally horizontal orientation, in a vertical takeoff and landing mode, and a generally vertical orientation, in a forward flight mode. A tailboom having an aft station extends from the aft portion of the fuselage. A cross-flow fan is disposed in the aft station of the tailboom and is operable to generate a pitch control moment.

Abstract: An aircraft has multiple independent yaw authority mechanisms. The aircraft includes an airframe having first and second wings with at least first and second pylons extending therebetween and with a plurality of tail members extending therefrom each having an active control surface. A two-dimensional distributed thrust array is coupled to the airframe that includes a plurality of propulsion assemblies each having a rotor assembly and each operable for thrust vectoring. A flight control system is operable to independently control each of the propulsion assemblies. A first yaw authority mechanism includes differential speed control of rotor assemblies rotating clockwise compared to rotor assemblies rotating counterclockwise. A second yaw authority mechanism includes differential longitudinal control surface maneuvers of control surfaces of two symmetrically disposed tail members. A third yaw authority mechanism includes differential thrust vectoring of propulsion assemblies.

Abstract: An aircraft has an airframe with a two-dimensional distributed thrust array attached thereto having a plurality of propulsion assemblies that are independently controlled by a flight control system. Each propulsion assembly includes a housing with a gimbal coupled thereto that is operable to tilt about first and second axes responsive to first and second actuators. A propulsion system is coupled to and operable to tilt with the gimbal. The propulsion system includes an electric motor having an output drive and a rotor assembly having a plurality of rotor blades that rotate in a rotational plane to generate thrust having a thrust vector. Responsive to a thrust vector error of a first propulsion assembly, the flight control system commands at least a second propulsion assembly, that is symmetrically disposed relative to the first propulsion assembly, to counteract the thrust vector error, thereby providing redundant directional control for the aircraft.

Abstract: An aircraft includes a composite structure, comprising an outer skin formed from a composite material and having a first thickness, an inner skin formed from a composite material and having a second thickness, the second thickness being greater than the first thickness, and a core structure positioned between the inner and outer skins to increase bending stiffness of the composite structure. During use a structural load carried by the inner skin exceeds a structural load carried by the outer skin.