A rotor blade has a spanwise axis, a root comprising an anchor having an anchor surface configured to form at least one of a normal angle relative to the spanwise axis and an acute angle relative to the spanwise axis, and a selectively removable tip comprising a connector having a connector surface configured to complement the anchor surface.

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 main rotor blade assembly for a rotary wing aircraft is provided including a main rotor blade root region, a main rotor blade inboard region arranged outboard of said main rotor blade root region, a main rotor blade main region arranged outboard of said main rotor blade inboard region, and a main rotor blade tip region arranged outboard of said main rotor blade main region. At least one of chord, twist, sweep, airfoil shape, and thickness/chord of the main rotor blade assembly has been optimized to achieve balanced high speed forward flight and hover relative to both efficiency and high thrust capability.

A main rotor blade assembly is provided including a spar which comprises a main section. A main core is positioned adjacent a trailing side of the main section of the spar. A tip assembly includes a main tip core and a tip end pocket core. The tip assembly is positioned adjacent an outboard end of the main core and the spar such that the main tip core is substantially aligned with a longitudinal axis of the main core and the tip end pocket core is substantially aligned with a longitudinal axis of the spar. At least a portion of both the main tip core and the tip end pocket core comprises a high density core. An upper composite skin and a lower composite skin extend over the spar, the main core, the main tip core, and the tip end pocket core. A portion of the upper composite skin and the lower composite skin has a thickness sufficient to be load bearing.

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 tip structure may be arranged for example on a rotor blade (12) of a HAWT (10). The tip structure comprises a pressure side structure (50) arranged on a pressure side (43) of the blade, and a suction side structure (60) arranged on a suction side (44) of the blade (12). The pressure side and suction side structures (50, 60) have different pitch angles (αP, αS) so that the chord (CP2) of the pressure side structure (50) extends forwardly in the direction of motion (D) and relatively more radially outwardly away from the blade root, or less radially inwardly towards the blade root, than the chord (CS2) of the suction side structure (60), defining a relative twist angle (αT) between the two structures (50, 60).

An electric power-generating system for a rotor blade includes at least one electromechanical power-converting device and at least one power-guide line, which is connected mechanically to the electromechanical power-converting device. The electromechanical power-converting device is configured in such a way that, during a movement of the power-guide line, the device converts into electric power the forces introduced by the movement of the power-guide line into the electromechanical power-converting device.

Vortex reduction apparatus for use with airfoils are disclosed. An example vortex reduction apparatus includes a housing to couple to a tip of an airfoil. The housing defines a volute fluid flow passageway between an inlet and an outlet. The volute fluid flow passageway is structured to induce a rotational fluid flow in a first rotational direction opposite a second rotational direction of a shed vortex induced at the tip of the airfoil during flight.

A proprotor blade for a ducted aircraft including a duct includes a main body having a distal end and a sacrificial blade tip coupled to the distal end of the main body. The sacrificial blade tip includes a deformable core material and a shell layer at least partially covering the deformable core material. The sacrificial blade tip deforms upon contact with the duct, thereby reducing damage to the ducted aircraft.

A tip gap control system for a ducted aircraft includes a flight control computer including a blade length control module configured to generate a blade tip actuator command and a proprotor system in data communication with the flight control computer. The proprotor system includes a duct and proprotor blades surrounded by the duct. Each of the proprotor blades includes an active blade tip movable into various positions including a retracted position and an extended position. The tip gap control system also includes one or more actuators coupled to the active blade tips. The one or more actuators move the active blade tips between the various positions based on the blade tip actuator command, thereby controlling a tip gap between the proprotor blades and the duct.