Abstract: A ducted-rotor aircraft includes a fuselage and first and second ducts that are coupled to the fuselage. Each duct includes a duct ring, a rotor having a plurality of blades, a hub that positions the rotor such that the blades define a blade plane of rotation within the duct ring, and a plurality of stators that are coupled to the hub at respective locations aft of the blade plane of rotation. Each of the plurality of stators defines a leading edge that is slanted toward the blade plane of rotation. The leading edges of the stators are slanted to follow a contour defined by the blades. The leading edges may also be slanted to maintain a distance of at least one blade inboard chord length between the leading edges of the stators and respective trailing edges of the blades.

Abstract: A rotor assembly configured to increase the stiffness of a rotor mast. The rotor assembly includes the rotor mast, a rotor hub, a mast nut, a mast bearing, and a cuff disposed between the mast nut and the mast bearing. The cuff is captured and compressed between the mast nut and the inner race of the mast bearing along an uninterrupted load path that extends between the mast nut and the mast bearing.

Abstract: A rotor assembly including a rotor mast, a rotor hub coupled to the rotor mast, a plurality of rotor blades coupled to the rotor hub, a control tube extending through the rotor mast, a crosshead coupled to the control tube, and a mechanism configured to drive the rotor mast in rotation. Wherein the mechanism is longitudinally positioned between a top portion and a bottom portion of the control tube and translation of the control tube relative to the rotor mast causes rotation of the rotor blades about their pitch-change axes. While the crosshead is installed, the crosshead is prevented from angular rotation about the mast axis. A pin of a rotor blade assembly is captured between opposing tabs of the crosshead and movable relative to the opposing tabs in response to translation of the crosshead along the mast axis.

Abstract: A rotor assembly has a rotor hub having a unitary structure. The rotor assembly further includes a unitary crosshead having a first upper tab and a first lower tab located vertically below the first upper tab. The first upper tab and the first lower tab define a slot therebetween to accept a first pin of the first rotor blade. A second upper tab and a second lower tab located vertically below the second upper tab define a slot therebetween to accept a second pin of the second rotor blade. A first recess is provided between the first lower tab and the second lower tab so that the crosshead comprises no material directly between at least a portion of the first lower tab and the second lower tab along at least one straight path.

Abstract: A rotor assembly has a rotor hub having a unitary structure. The rotor assembly further includes a unitary crosshead having a first upper tab and a first lower tab located vertically below the first upper tab. The first upper tab and the first lower tab define a slot therebetween to accept a first pin of the first rotor blade. A second upper tab and a second lower tab located vertically below the second upper tab define a slot therebetween to accept a second pin of the second rotor blade. A first recess is provided between the first lower tab and the second lower tab so that the crosshead comprises no material directly between at least a portion of the first lower tab and the second lower tab along at least one straight path.

Abstract: A ducted-rotor aircraft includes a fuselage and first and second ducts that are coupled to the fuselage. Each duct includes a duct ring, a rotor having a plurality of blades, a hub that positions the rotor such that the blades define a blade plane of rotation within the duct ring, and a plurality of stators that are coupled to the hub at respective locations aft of the blade plane of rotation. Each of the plurality of stators defines a leading edge that is slanted toward the blade plane of rotation. The leading edges of the stators are slanted to follow a contour defined by the blades. The leading edges may also be slanted to maintain a distance of at least one blade inboard chord length between the leading edges of the stators and respective trailing edges of the blades.

Abstract: A rotor assembly including a rotor mast, a rotor hub coupled to the rotor mast, a plurality of rotor blades coupled to the rotor hub, a control tube extending through the rotor mast, a crosshead coupled to the control tube, and a mechanism configured to drive the rotor mast in rotation. Wherein the mechanism is longitudinally positioned between a top portion and a bottom portion of the control tube and translation of the control tube relative to the rotor mast causes rotation of the rotor blades about their pitch-change axes. While the crosshead is installed, the crosshead is prevented from angular rotation about the mast axis.

Abstract: A rotor assembly has a rotor hub having a unitary structure. The rotor assembly further includes a unitary crosshead having a first upper tab and a first lower tab located vertically below the first upper tab. The first upper tab and the first lower tab define a slot therebetween to accept a first pin of the first rotor blade. A second upper tab and a second lower tab located vertically below the second upper tab define a slot therebetween to accept a second pin of the second rotor blade. A first recess is provided between the first lower tab and the second lower tab so that the crosshead comprises no material directly between at least a portion of the first lower tab and the second lower tab along at least one straight path.

Abstract: A rotor assembly configured to increase the stiffness of a rotor mast. The rotor assembly includes the rotor mast, a rotor hub, a mast nut, a mast bearing, and a cuff disposed between the mast nut and the mast bearing. The cuff is captured and compressed between the mast nut and the inner race of the mast bearing along an uninterrupted load path that extends between the mast nut and the mast bearing.

Abstract: One embodiment is a bearing carrier assembly including a circular shield having top and bottom surfaces; and a number of bearing separators integrated with the bottom surface of the shield, wherein each pair of bearing separators defines a receptacle for receiving and retaining a bearing therewithin and wherein the shield blocks the received bearings from debris and retains lubricant around the received bearings. Each of the bearing separators may include a spacer element for separating adjacent ones of the bearings. The bearing carrier assembly may be made up of a number of carrier sections that interconnect to form the bearing carrier assembly.

Abstract: An aircraft having a differential rotor speed resonance avoidance system. The aircraft includes an airframe having structural elements subject to resonant vibration at critical frequencies. A thrust array is coupled to the airframe. The thrust array includes at least four rotor systems distributed about the airframe, each rotor system operable over a range of rotor speeds. A flight control system is operably associated with the thrust array and is configured to independently control the rotor speed of each rotor system. While preserving flight dynamics during flight operations, the flight control system selectively increases the rotor speed of some of the rotor systems by a speed delta and decreases the rotor speed of others of the rotor systems by the speed delta to avoid generating excitation frequencies by the rotor systems at the critical frequencies.

Abstract: A method of performing structural analysis relating to a component having CAD-based geometry, refined CAD-based geometry and CAD-based FEA data associated therewith. The method includes scanning the component to obtain scan-based point cloud geometry of the component, aligning the scan-based point cloud geometry with the CAD-based geometry of the component, generating scan-based geometry of the component by refining the scan-based point cloud geometry, comparing the scan-based geometry with the refined CAD-based geometry of the component to quantify geometric differences therebetween, generating scan-based FEA geometry of the component by meshing the scan-based geometry, performing finite element analysis on the scan-based FEA geometry to obtain scan-based FEA data and comparing the scan-based FEA data with the CAD-based FEA data of the component to quantify the effect of geometric difference therebetween.

Abstract: In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.

Abstract: A method of performing structural analysis relating to a component having CAD-based geometry, refined CAD-based geometry and CAD-based FEA data associated therewith. The method includes scanning the component to obtain scan-based point cloud geometry of the component, aligning the scan-based point cloud geometry with the CAD-based geometry of the component, generating scan-based geometry of the component by refining the scan-based point cloud geometry, comparing the scan-based geometry with the refined CAD-based geometry of the component to quantify geometric differences therebetween, generating scan-based FEA geometry of the component by meshing the scan-based geometry, performing finite element analysis on the scan-based FEA geometry to obtain scan-based FEA data and comparing the scan-based FEA data with the CAD-based FEA data of the component to quantify the effect of geometric difference therebetween.

Abstract: In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.

Abstract: In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.

Abstract: In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.

Abstract: In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.

Abstract: In accordance with one embodiment of the present application, an actuation system is configured for actuation of an airfoil member with a flap mechanism. The actuation system can include an upper drive tape and a lower drive tape, each partially wrapped around a first bearing and second bearing. An inboard frame can be actuated by at least one linear actuator. Similarly, an outboard frame can be actuated by at least one linear actuator. The inboard frame is coupled to the upper drive tape, while the outboard frame is coupled to the lower drive tape. An actuation of the inboard frame and outboard frame in a reciprocal manner acts move a flap input lever reciprocally upward and downward. A flap mechanism is configured to convert the movement of the flap input lever into rotational movements of the airfoil member.

Abstract: A shield that protects high-value input resistors in a power meter against unwanted effects due to electromagnetic interference from a nearby power supply and/or due to crosstalk from adjacent phases. The shield includes multiple printed circuit board shields that are arranged between each of the input resistors on a main printed circuit board in the power meter. Each PCB shield has a conductive layer that provides the shielding against unwanted energy. The resistors are arranged in a diagonal or parallel manner between each pair of PCB shields to prevent the resistor from movement, which prevents pin fatigue and fixes the value of the parasitic capacitance that is produced in the resistor-PCB-shield combination. In another configuration, the PCB shield is made of a flexible material, and snakes between and over the top or around the side ends of each resistor in a serpentine fashion, protecting the resistors from unwanted energies from both the top and the sides.