Abstract: Embodiments are directed to systems and methods for determining an optimal engine inlet area to minimize spillage drag. An algorithm may utilize aircraft parameters, aircraft performance charts, and engine models to determine the engine inlet area as a function of engine air mass flow, airspeed, and air density at current ambient conditions.

Abstract: A high-performance descent system for a multi-rotor aircraft includes a flight control computer comprising a processor, a propulsion system communicatively coupled to the flight control computer and configured to allow a direction of thrust relative to a vertical z-axis to be selected by the flight control computer. The processor is operable to implement a method including preparing the multi-rotor aircraft for a high-performance descent, instructing, via a flight control system, a proprotor to reduce an amount of vertical thrust produced by the proprotor by tilting the proprotor away from a vertical axis, and reducing an altitude of the multi-rotor aircraft.

Abstract: An exemplary ducted fan includes a circular duct surrounding a rotor hub from which blades radially extend, a stator having a stator leading edge and a stator trailing edge, and a stator chord line extending from the stator leading edge to the stator trailing edge, the stator chord line substantially equal to a duct radius from the rotor hub to an outer surface of the duct.

Abstract: An exemplary ducted fan with an optimized stator includes a duct surrounding a rotor hub from which blades radially extend and the stator having a stator span extending horizontally across an inside diameter of the duct, the stator having a stator chord extending from a leading edge to a trailing edge, wherein a length of the stator chord varies across the stator span.

Abstract: A method of reducing noise generated by a tilt-rotor aircraft includes transitioning the tilt-rotor aircraft into an airplane mode from a helicopter mode, and reducing a speed of a plurality of rotor blades of a first pair of rotors of the tilt-rotor aircraft to be less than a speed of a plurality of rotor blades of a second pair of rotors that are positioned forward of and in-line with the first pair of rotors. A flight control system configured to reduce a noise level of a tilt-rotor aircraft includes a flight control computer comprising a processor, a propulsion system communicatively coupled to the flight control computer, a first pair of rotors and a second pair of rotors communicatively coupled with the flight control computer and the propulsion system.

Abstract: Embodiments are directed to systems and methods for deploying an outboard rotor blade of proprotor pylon to act as an extended lifting surface. Blade control actuators may provide primary rotor flight control as well as providing fold linkage actuation when fold locks are disengaged. During cruise flight, the blade control actuator may provide feathering inputs to the extended rotor blade, wherein the amplitude and frequency of feathering inputs are tuned to mitigate undesirable wing and fuselage dynamic modes thereby enhancing aircraft stability. The deployed rotor blades also improve the total lifting area of the aircraft, which may increase aircraft range and efficiency.

Abstract: A method of pitching rotor blades by interrupting torque applied to the hub.

Abstract: A method of reducing noise generated by a tilt-rotor aircraft includes transitioning the tilt-rotor aircraft into an airplane mode from a helicopter mode, and reducing a speed of a first pair of fans of the tilt-rotor aircraft to be less than a speed of a second pair of fans that are positioned in-line with the first pair of fans. A flight control system configured to reduce a noise level of a tilt-rotor aircraft includes a flight control computer comprising a processor, a propulsion system communicatively coupled to the flight control computer, a first pair of fans and a second pair of fans communicatively coupled with the flight control computer and the propulsion system. The processor is operable to implement a method that includes transitioning the tilt-rotor aircraft into an airplane mode from a helicopter mode, and reducing a speed of the first pair of fans to be less than a speed of the second pair of fans that are positioned in-line with the first pair of fans.

Abstract: An exemplary tiltrotor aircraft having a vertical takeoff and landing (VTOL) flight mode and a forward flight mode includes tiltable rotors located at forward boom ends, tiltable ducted fans located at wings aft of the forward boom ends, and aft rotors located on aft boom portions.

Abstract: An air-cooled fuel-cell freeze-protection system for a rotorcraft using a controller to vary a heating system for an air-cooled fuel cell. The heating system heats supply air for the air-cooled fuel cell, and a butterfly valve varies a pressure of the supply air to the air-cooled fuel cell. The heating system can be an electric heater, a heat exchanger, or a combination of heater and heat exchanger.

Abstract: A rotorcraft includes a fuselage with at least one rotor assembly coupled thereto. A drivetrain provides rotational energy to the rotor assembly. The drivetrain includes an engine and a gearbox having a gearbox housing. A gearbox cooling fin array including a plurality of cooling fins is bonded to the gearbox housing with a thermal interface material. The gearbox cooling fin array is configured to dissipate heat generated by the gearbox during operation of the rotorcraft.

Abstract: A differential thrust vectoring system including a first thruster rotation assembly configured to rotate a first thruster relative of an aircraft, a second thruster rotation assembly configured to rotate a second thruster of an aircraft, and an actuator. The system is configured such that actuation of the actuator causes disparate rotation about the tilt axis of the first and second thrusters.

Abstract: An exemplary tail rotor includes a first blade assembly configured to rotate in a first direction about an axis of rotation and a second blade assembly configured to rotate in a second direction about the axis of rotation.

Abstract: A rotor mast including an outer member defining a channel therethrough and an inner member disposed in the channel through the outer member, wherein the inner member is configured to apply a compressive force to the outer member.

Abstract: A method of blade fold for a tiltrotor aircraft includes configuring the tiltrotor aircraft in a flight ready position with a rotor system in an inverted-Y position, unlocking a first rotor blade of the rotor system to permit the first rotor blade to pivot relative to a yoke of the rotor system, restraining the first rotor blade to allow the first rotor blade to pivot relative to the yoke as the yoke is rotated, rotating the rotor system in a first direction so that the first rotor blade pivots closer to a second rotor blade, rotating the rotor system in a second direction to orient the rotor system into a modified inverted-Y position, unlocking a third rotor blade to allow the third rotor blade to pivot relative to the yoke as the yoke is rotated, and rotating the rotor system in the second direction so that the third rotor blade pivots closer to the second rotor blade.

Abstract: In a first aspect, there is a helicopter skid landing gear assembly including a front cross tube configured to interconnect two skid tubes; and a rear cross tube configured to interconnect two skid tubes; wherein at least one of the cross tubes comprises a monolithic metallic tube having a cross-section with a round exterior shape and an elliptical hollow portion therein. In a second aspect, there is a method for retrofitting a helicopter with a landing gear assembly; the method including providing a front cross tube and a rear cross tube, at least one of the front cross tube and the rear cross tube comprises a monolithic metallic tube having a cross-section with a substantially round exterior shape and an elliptical hollow portion therein; and connecting the front cross tube and rear cross tube to a fuselage.

Abstract: A system includes an engine cover covering a side-facing rotorcraft engine and having an opening and an ice protection member mounted on the engine cover between the opening and the engine, an area of the ice protection member smaller than an area of the opening. The ice protection member is configured to partially cover the opening to prevent ice having a particular size from entering into the engine and to allow air flow downstream into the engine.

Abstract: A composite assembly has an outer spar component having an outer spar component inner profile, an inner spar component having an inner spar component outer profile substantially complementary to the outer spar component inner profile, and an adhesive disposed between the outer spar component and the inner spar component.

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: A side-by-side off-road utility vehicle comprising a vehicle operational status switch for controlling the operational status of the vehicle, a side-by-side seating structure, a plurality of safety restraint devices operable to retain one or more vehicle passenger in the side-by-side seating structure, and a prime mover RPM controller. The prime mover RPM controller operable to output commands to the one or more prime mover of the vehicle to limit a rotational speed of the prime mover(s) when the vehicle is in an On operational status and a selected one or more of the one or more safety restraints is in a disengaged status.