A rotor system for a rotorcraft has a hub rotatable about an axis and a plurality of blades coupled to the hub for rotation therewith about the axis. Each blade is capable of rotation about a pitch axis relative to the hub, and a ring couples adjacent blades to each other.

A propeller includes a blade. The blade includes a blade root, a blade tip disposed away from the blade root, a blade front surface, and a blade back surface. The blade also includes a front edge connecting a first side of each of the blade front surface and the blade back surface. The blade also includes a rear edge connecting a second side of each of the blade front surface and the blade back surface. The blade further includes a first suppression member formed by a portion of the front edge adjacent to the blade tip bending toward a first direction. The first direction is a direction from the front edge to the rear edge. The first suppression member is configured to suppress a spanwise air flow.

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.

An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

A method of mounting a replacement tip section to an exposed end of a rotor blade includes removing an existing tip section from the rotor blade to create the exposed end of the rotor blade, installing the rotor blade having the exposed end onto a holding fixture, assembling the replacement tip section about the exposed end of the rotor blade, positioning a bonding fixture about the replacement tip section, and curing the replacement tip section to the exposed end of the rotor blade.

A system for regenerating fastener holes in a replacement tip section of a rotor blade includes a first fixture, a second fixture, and a third fixture positionable adjacent a tip section of the rotor blade. The first fixture is used to verify a position of an opening formed in the spar. The second fixture includes a removable bushing having a drillable opening. The drillable opening is aligned with the at least one opening formed in the spar and defines at least one hole to be formed in the replacement tip section. The third fixture includes a countersink opening. The countersink opening is aligned with the at least one hole to be formed in the replacement tip section and the at least one opening formed in the spar to define a countersink feature to be formed in the at least one hole.

A rotor blade for an aircraft includes first and second blade tips, a blade body, and a vortex-generating blade. The blade body has an end forming the first blade tip of the rotor blade and an airfoil section configured such that during rotation, pressure acting on a lower surface of the blade body is greater than pressure acting on an upper surface of the blade body. The vortex-generating blade is disposed at an end of the rotor blade and forms the second blade tip. The vortex-generating blade also has an airfoil section configured such that during rotation, pressure acting on a lower surface of the vortex-generating blade is smaller than pressure acting on an upper surface of the vortex-generating blade.

A flight system for an aircraft and method for controlling a clearance between a first rotor disk and a second rotor disk of an aircraft is disclosed. The flight system includes a sensor for measuring an angle of deviation of at least one of a first rotor disk and a second rotor disk of the aircraft to indicate a clearance between the first rotor disk and the second rotor disk as well as sensors for measuring a flight condition of the aircraft. A control allocation module uses the measured angle of deviation and the flight condition of the aircraft to determine an allocation of control settings to axis-controlling devices of the aircraft to attain a selected pitch of the aircraft, wherein the allocation is based at least on the measured angle of deviation and the flight state of the aircraft.

A tiltrotor aircraft is designed to accommodate rotors of different diameters, as well as corresponding wings and fuselages with different span and length, while maintaining very high parts commonality, especially with respect to drive train and power source. This enables design and operation of a fleet of such aircraft with significantly different rotor diameters, which are nevertheless optimized for different missions. In preferred embodiments the rotors are configured to have high stiffness and low weight to reduce aero-structural dynamic issues across the fleet. Also in preferred embodiments drive systems are designed for a full range of speed, torque, and power associated with all intended rotors. Turboshaft engine speeds are restricted to a narrow RPM range, so that a single gearset can be replaced to achieve the desired rotor RPM. Also in preferred embodiments, aircraft in a fleet can differ in folded length, empty weight, payload length by up 50%.

An arrangement of lifting surfaces including a primary lifting surface having a flexural axis extending in the spanwise direction of the lifting surface, a root, and a tip. A first tip device is attached to the tip and has a first lifting surface. A second tip device is attached to the tip and has a second lifting surface. A control system is coupled to the first and second tip devices for moving the first and second lifting surfaces relative to the tip and/or for actively controlling circulation of the first and second lifting surfaces. The control system is operable to change a value of torque effective at the primary lifting surface about the flexural axis. Also, a method of controlling an arrangement of lifting surfaces.