A helicopter has a mast axis and a rotorcraft blade assembly. The rotorcraft blade assembly has a main body and a blade tip movable relative to the main body. The rotorcraft blade assembly is selectively rotatable about the mast axis.

A rotor blade for a rotary wing aircraft and a tip for the rotor blade. The rotor blade includes a blade root, a blade tip and a blade body that extends from the blade root to the blade tip. The blade tip includes: a continuously swept leading edge, a compound trailing edge, and a continuous anhedral.

In an embodiment, a layer material configured to be arranged on a rotor blade tip of a helicopter comprises at least one light emitting or reflecting section that emits or reflects light after being exposed to a remote light source. The light source can be arranged on the body of the helicopter.

Ground effect acting on an aerial vehicle, such as an unmanned aerial vehicle, may be simulated by discharging a gas around propeller blades of the aerial vehicle while the propeller blades are rotating. For example, a gas, such as air, may be discharged at or near the tip of the propeller blades with enough velocity to disrupt the airflow around the blade tips, thereby altering the sound generated by rotation of the propeller blade.

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.

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.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.

A blower wheel comprises a hub, a guide and blades extending radially between the hub and the guide, each blade comprising a root at its junction with the hub and a head at the junction with the guide, each blade having a leading edge and a trailing edge between which, at each flattened cross section, a chord is defined. For each blade, between the root and the head, the length of the chord varies and the variation in the length of chord between the root and the head has a point of inflexion between two levels.

A caul assembly includes a semi-rigid caul plate formed in a shape complementary to a portion of a component receivable therein and a heater located at an exterior surface of the semi-rigid caul plate. The heater is adapted to apply heat to a localized portion of the component.

A wing having a wing box (20) defining a first wing profile with a first leading edge, a first trailing edge, a first top surface and a first bottom surface; a first appendage hinged on the wing box and defining a second wing profile, in turn comprising an end wall and a second trailing edge, a second top surface and a second bottom surface; the first appendage is movable between: a first position, in which the first and the second wing profiles are contiguous with each other and a second position, in which the second bottom surface and second top surface are respectively separated from the first bottom surface and first top surface; the wing box comprises a first spar having a curved section in a plane orthogonal to the associated first axis; the end wall is curved and arranged abutting against the first spar at least along the second top surface and the second bottom surface when the first movable appendage is in the first position.